# Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)



## greybeard (Jan 25, 2018)

Hello!
I was intrigued by reading of this interview with Golodnikov, especially by his mention about true performances of German fighters (color plus some correction of the text by me):

"*A. S. Nikolay Gerasimovich, if you look at any reference book, the superiority in speed of German aircraft [like] the Bf-109G and FW-190 is indisputable. Minimum 20-25 kilometers at low altitudes and up to 80-100 kilometers at high altitudes. And you say ours did not lag behind?*
_
* N. G.* No, some difference in speed always exists. At low altitudes we were a bit faster, at high altitudes they were. The difference was on the order of 10-20 km. But this difference was not so great that it ensured overwhelming superiority. In combat it was practically not discernible.
_
* A. S. Nikolay Gerasimovich, sometime relatively long ago I was speaking with a pilot, a frontline veteran. Right after the war they flew in captured aircraft. And no matter how hard they tried, they were unable to attain the speeds the Germans had written in their specifications. The shortfall in speed was significant. In the end, they prevailed upon a German, a high-level specialist, and asked him, "Why this shortfall in speed? Are we using the engine's capability incorrectly?" His response was that they would never achieve the target speed, because the German specifications showed the theoretical speed, and they were attempting to attain that speed on their instruments.*

* Nikolay Gerasimovich, in your view, is this possible?*
_
* N. G. * Of course. We had a group of specialists with us from NII VVS. They were examining specifications and were looking at speed. "What speed is indicated at 7,000 meters? 780? Take away 100. And what about 3,000 meters? 700? Reduce it 70 km." This is how they calculated the instrumented speed and, characteristically, almost always hit their target. Perhaps they knew something about our focus on speed._"

I wonder what they mean for "theoretical speed": didn't Germans actually test in flight their planes? And what is this "instrument speed" they speak of?

I would be glad to know your opinion. Cheers,
GB

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## MIflyer (Feb 2, 2018)

I recall reading of one German pilot saying, "The P-39 performed like the 109 at low altitudes."

And in the book "P-39 Aces of WWII" the author points out that in reality P-39 versus Zero losses in the Pacific were about equal. He also points out that when the Soviets got in later aircraft such as the LA-5, Yak-3, and Yak-9 they did not use them to replace P-39's but kept the Airacobras in front line air superiority service.

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## pbehn (Feb 2, 2018)

The war in the east was always on a land front, this may have been static or fluid but it was over land, apart from N Africa the majority of conflicts in the west had a water barrier until 1944. The P 39 may have been disadvantaged at high altitude, but the fight was at the front was on the ground where the two sides armies were in conflict . After D Day the fight in the east and west was pretty much the same on the front. The Typhoon and Tempest were disadvantaged at altitude but that was of no consequence because to take the fight up to high altitude needs strategic bombers or recon aircraft.

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## FLYBOYJ (Feb 2, 2018)

MIflyer said:


> I recall reading of one German pilot saying, "The P-39 performed like the 109 at low altitudes."
> 
> And in the book "P-39 Aces of WWII" the author points out that *in reality P-39 versus Zero losses in the Pacific were about equal.* He also points out that when the Soviets got in later aircraft such as the LA-5, Yak-3, and Yak-9 they did not use them to replace P-39's but kept the Airacobras in front line air superiority service.


There were few old discussions on this. There is no doubt the Zero had the definite advantage over the P-39 over New Guinea, but if you look at the combat record of say the 8th FG, the P-39's combat record wasn't as dismal as portrayed by some historians.

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## MIflyer (Feb 2, 2018)

One thing I've wondered about is just how much difference there was between the P-39D and the P-400. The P-400 had the RAF oxygen system that was incompatible with the US equipment and the 20MM gun, which probably was actually better than the 37MM for air to air combat. It also had the SCR-283 radio rather than the much better 274-N. But the P-39D-1 was simply a P-400 brought up to P-39 standards, but retaining the 20MM gun. Other than that I see no reason to suspect a real difference in the performance of the two types. But the conditions on Guadalcanal were a lot worse than on New Guinea and the maintenance no doubt suffered.

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## Denniss (Feb 3, 2018)

P-39 was a fine aircraft at low level.
One should not forget that the soviets tended to improve the P-39 by saving weight, removing wing cannon and sometimes even armor plates and other stuff.
The weight savings should have helped with maneuverability and speed/acceleration

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## XBe02Drvr (Feb 3, 2018)

greybeard said:


> I wonder what they mean for "theoretical speed": didn't Germans actually test in flight theirSS planes? And what is this "instrument speed" they speak of?


Sounds to me like a loosely translated reference to speed under optimum conditions as opposed to indicated airspeed under real world conditions. Perhaps akin to the difference in SAE vs DIN horsepower ratings back in the musclecar days. SAE measured the output of the raw engine block, with all accessory functions such as coolant circulation, electrical generation, and carburetion provided by the test rig, while DIN measured horsepower delivered to a transmission by a fully assembled engine as it would be installed in a car. Make sense?
I think the "theoretical" speeds might have been measured speeds of (perhaps prototype) thoroughly instrument test aircraft corrected for temperature pressure and altitude. The indicated airspeed of a frontline aircraft in combat trim would obviously be much lower.
Cheers,
Wes

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## MIflyer (Feb 4, 2018)

Well, the P-39 did not have any “Wing Cannons” to delete. But ever since reading Caiden’s “Rugged, Ragged Warriors” I have wondered if you could strip a P-39 down a bit to yield a better air to air fighter. They did that with a P-40 in India with a degree of success in intercepting Japanese Dinah recon aircraft.

Take a look at the P-39 Design Analysis. The 37MM gun was not all that useful in air to air combat. It had a rate of fire described as similar to that of a “Roman Candle” which was supposed to be 135 rounds a minute; at 300 mph the airplane would have moved 200 ft between rounds. Even more importantly, the 37MM trajectory was significantly different from that of the .50 cal and .30 cal guns, so it usually was a matter of deciding which gun you wanted to hit the target with.

So let’s get rid of the 37MM and replace it with another .50 cal. The 37MM weighs 238 lb and its 30 rounds of ammo weighs 60 lb, for a total of 298 lb saved. One .50 cal gun weighs 80 lb and 400 rounds of ammo for it weighs 129 lb (the two .50 cal guns already there have 200 rpg). So, swapping out the 37MM for a .50 saves 89 lb.

Next let’s get rid of the four .30 cal guns in the wings. That saves 92 lb for the 4 guns and 78 lb for the 1200 rounds of ammo. By the way supposedly the P-39 could hold 2000 rounds of .30 cal ammo but they probably did not load all of it. We get rid of another 170 lb, for a total reduction of 259 lb, which is not really very much.

The total weight of armor plate for the airplane is given as 202 lb. I read somewhere that one unit in the Pacific made a big improvement in the P-39 by removing the armor on the belly protecting the radiator. If you are planning on air-to-air work that belly armor is not very useful, but I’m sure it was useful for strafing.

So if you get rid of, say, half the armor and you have stripped the airplane down to three .50 cal guns, it is 359 lb lighter. That does not sound like very much to me. No wonder they never seemed to try it. It appears that the P-39Q-20 without the two underwing .50 cal guns was about 260 lb lighter than the other Q models. The P-39N-0-BE model had four fuel cells removed to reduce the max fuel load by 28 gal, which reduced the max gross weight from 9100 to 8750 lb. So if a 350 lb weight reduction was worth doing then maybe 359 lb would be worth doing.

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## XBe02Drvr (Feb 4, 2018)

MIflyer said:


> So if a 350 lb weight reduction was worth doing then maybe 359 lb would be worth doing.


WHOA!! So far all this weight you've removed seems to be forward of the center of lift. Don't forget this is a rear engine plane with a hint of a tail heaviness problem. If you don't compensate by moving some heavy objects forward, you're going to have a right squirrelly bastard on your hands with some nasty slow flight and stall behaviors and a penchant for unrecoverable flat spins. This wheel has been invented before!
Cheers,
Wes

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## tomo pauk (Feb 4, 2018)

MIflyer said:


> Well, the P-39 did not have any “Wing Cannons” to delete. But ever since reading Caiden’s “Rugged, Ragged Warriors” I have wondered if you could strip a P-39 down a bit to yield a better air to air fighter. They did that with a P-40 in India with a degree of success in intercepting Japanese Dinah recon aircraft.
> 
> Take a look at the P-39 Design Analysis. The 37MM gun was not all that useful in air to air combat. It had a rate of fire described as similar to that of a “Roman Candle” which was supposed to be 135 rounds a minute; at 300 mph the airplane would have moved 200 ft between rounds. Even more importantly, the 37MM trajectory was significantly different from that of the .50 cal and .30 cal guns, so it usually was a matter of deciding which gun you wanted to hit the target with.
> 
> ...



There was no belly armor on the P-39. 
In order to compensate for lighter front end, remove the rearmost armor plate (the one behind the oil tank) and replace it with aluminium type. Keep the number of radios to one. Less gun & spent cartridge openings = less drag, so indeed remove the wing guns. Keep the fuel tankage, radius is is already short for Pacific.



XBe02Drvr said:


> WHOA!! So far all this weight you've removed seems to be forward of the center of lift. Don't forget this is a rear engine plane with a hint of a tail heaviness problem. If you don't compensate by moving some heavy objects forward, you're going to have a right squirrelly bastard on your hands with some nasty slow flight and stall behaviors and a penchant for unrecoverable flat spins. This wheel has been invented before!
> Cheers,
> Wes



Wing gus are as close to the centre of lift as possible.


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## MIflyer (Feb 4, 2018)

Yes, it goes without saying that clearly the CG would have to be addressed, as the P-39 without either ammo or suitable ballast in the forward compartment displayed some unpleasant handling characteristics. I'd consider moving the aircraft battery forward, perhaps even to the nose compartment which is probably the most common approach; the battery weighed 76 lb, so it was a pretty substantial influence.

As for "no belly armor" I guess that WWII fighter pilot did not know what he was talking about. Maybe he meant the armor behind the engine.


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## FLYBOYJ (Feb 4, 2018)

Keep in mind the P-39 also had 2 CG datum points


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## XBe02Drvr (Feb 4, 2018)

FLYBOYJ said:


> Keep in mind the P-39 also had 2 CG datum points


Explain please? That's a new one on me. Thanks.


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## FLYBOYJ (Feb 4, 2018)

XBe02Drvr said:


> Explain please? That's a new one on me. Thanks.


It had a vertical and horizontal C/G, just like a helicopter. I'll try to find the W&B form

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## FLYBOYJ (Feb 4, 2018)

P20A P-39Q pilot manual

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## swampyankee (Feb 4, 2018)

The more I keep learning about how US aircraft like the P-39 and P-40 performed in Europe, the more it's apparent that these aircraft have been maligned.

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## pbehn (Feb 4, 2018)

swampyankee said:


> The more I keep learning about how US aircraft like the P-39 and P-40 performed in Europe, the more it's apparent that these aircraft have been maligned.


I don't know why, for me, their performance is respected for what they were, some habitually compare them to a P 51 which was from a different era doing a different job.

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## Greg Boeser (Feb 4, 2018)

Some of the problem with the P-39 in North Africa is it was recognized as obsolete and the pilots flew them accordingly. 
In the Pacific, the P-39 was rated better than the P-40 by those who flew them, but we are comparing P-40E to P-39D in Pacific vs P-40F vs P-39D in North Africa. The Merlin did give the P-40 an advantage over the P-39.

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## DKoor (Feb 8, 2018)

From the moment I've heard about the type, I've read mostly positive things about it.
Granted it were Soviet experiences with the type... there is a good book about their experiences "Attack of the Airacobras", some very good read.
I may be 'pushing it' a bit if I say that if the game "IL-2 Sturmovik" is ANYTHING to go by, P-39 was truly fearsome weapon if piloted by a grizzled veteran.
Even when confronted by some of the era best aircraft such as Bf-109 and FW-190. Also, curiously I've seen several VVS pilot opinions where they regard 109 as a bit more capable plane that 190. That may be due to nature of Eastern Front warfare and many other things.

To return to "IL-2 Sturmovik"... I've flown/played that game for years and can say without any doubt that (in-game) P-39 is very capable plane, at least on Eastern front scenarios... when you mix it up with enemy fighters the way you shouldn't (flashy dogfights), and you gain upper hand they usually tend to shallow dive away. P-39 can follow them without problem and shot them down. Same thing if they try high speed maneuvers during dive... Cobra is quite fast in such type fights, more capable than early/mid-war Lavochkin and Yak types which often lose their opponents during hi-speed shallow dives. Also that NS-37 nose cannon... lower rate of fire, but I guess once pilot gets some experience under his belt shouldn't be an issue (when compared to the higher rof 20mm cannons). One shot can cripple bomber, and is usually insta-kill vs fighter.
So it is not a surprise to me when I see how several of the highest scoring Soviets flew this type.

Cobra was not so popular on the far East fronts... but then again I guess nothing really was truly popular (allied side) there in those days vs Zero until Hellcat arrived and gained upper hand in performance. At least in pilot's eyes. Because let's face it, if pilot go into actual combat he is not really interested in any kind of equal fights or proving himself in lesser types, what pilots really wanted is a truly superior type which could regularly bring success in combat..

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## FLYBOYJ (Feb 8, 2018)

DKoor said:


> From the moment I've heard about the type, I've read mostly positive things about it.
> Granted it were Soviet experiences with the type... there is a good book about their experiences "Attack of the Airacobras", some very good read.
> I may be 'pushing it' a bit if I say that if the game "IL-2 Sturmovik" is ANYTHING to go by, P-39 was truly fearsome weapon if piloted by a grizzled veteran.
> Even when confronted by some of the era best aircraft such as Bf-109 and FW-190. Also, curiously I've seen several VVS pilot opinions where they regard 109 as a bit more capable plane that 190. That may be due to nature of Eastern Front warfare and many other things.
> ...


Please don't compare historical aircraft performance to a game. Unless you're prepared to make comparisons in full motion simulators that could simulate actual G loading as well as other external stimuli encountered while in combat, or fly the real thing, you're basically guessing

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## michaelmaltby (Feb 8, 2018)

... but ... _ that _being said "the P-39 _was _an awesome gun platform to be exploited by skilled Soviet pilots" is the long and the short of it.  (Gamers are Gamers ... it's better than shooting craps, I suppose) 
The P-39 _and_ the Bell Support Package _and_ the LL gas boosters _and_ lubes etc. replacement Allison's etc, radios etc. _plus_ an under 15,000 feet war all combined to make the P-39 Official, Honored, Hero Warbird of the Soviet Union. Maybe the worlds's gamers could lobby Putin for that award.
Dimity Loza's "Attack of the Airacobras" is a great record with lots of insights.

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## MIflyer (Feb 8, 2018)

I'm a private pilot. I have been flying since 1975 and have about 1100 hours. I usually fly a half dozen times or more every month. I have flown the T-33A and T-37 a little as well as a 1929 Waco biplane. I have flown formation with other aircraft a number of times.

I have played a bit with flight simulators and had a lot of fun with Secret Weapons of the Luftwaffe. And I can tell you there is NO connection between flying computer games and the real thing.

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## ODonovan (Feb 8, 2018)

I've read up quite a bit on the P-39 as it was one of my favorite planes, growing up. P-38s and P-39s...luvz me mah trikes! 

From what I understand, the 39s were "tweaked" by the Russians by removing the outboard MGs to increase the roll rate. Other than that, they were pretty much standard. They used them with great success even past the middle of the war, against German fighters. The 39 started out getting a "bum rap" in the US when it got the reputation for being squirrely and going end over end at times. It was found that the CG went too far to the rear unless the plane was flown with a full ammo compartment in front. After that, they carried at least the weight of a full load of spent shell casings up front, and the stability problems went away. The plane was a favorite of the Russians (and was hated by the Germans) for a reason. 

That being said, I play World War II Online (wwiionline.com), a combined arms sim. They have the P-39 ingame. In fact, they've just added "tankbusters" to each side. The "Jerries" got the Stuka with twin cannons, the Brits got the Hurricane with twin cannons, and the French got the P-39. It's not as good against tanks, but it's nasty as all get out against other planes. Since the cannon fires down the centerline, through the spinner, it has no convergence to worry about.

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MIflyer said:


> I'm a private pilot. I have been flying since 1975 and have about 1100 hours. I usually fly a half dozen times or more every month. I have flown the T-33A and T-37 a little as well as a 1929 Waco biplane. I have flown formation with other aircraft a number of times.
> 
> I have played a bit with flight simulators and had a lot of fun with Secret Weapons of the Luftwaffe. And I can tell you there is NO connection between flying computer games and the real thing.



That's not ENTIRELY true. Check out the guy in the first vid. He even sticks a three pointer. Luvz me mah trikes! 







-Irish

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## gumbyk (Feb 8, 2018)

ODonovan said:


> That's not ENTIRELY true. Check out the guy in the first vid. He even sticks a three pointer. Luvz me mah trikes!
> 
> 
> -Irish



You don't three-point a nose-wheel aircraft - that's a recipe to end up with only two wheels left on the aircraft. I'd much rather see a heavier landing on the mains first than a flat three-pointer.

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## MIflyer (Feb 8, 2018)

"Manages a three pointer" HA! A three pointer in a tricycle gear airplane is NOT a good thing. Any idiot can drive one into the ground and let the landing gear soak up the impact - although it is done pretty often even by people who should know better. A proper landing is to alight on the MLG and then let the nose gear come down. A three pointer is fine on a taildragger - a lot better than hitting on the tailwheel and letting the main gear slam down.

The nose gear on a Cessna 150, for example is really pretty flimsy, as they say, "keeps the prop from hitting the ground when it is parked."

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## pbehn (Feb 8, 2018)

ODonovan said:


> I've read up quite a bit on the P-39 as it was one of my favorite planes, growing up. P-38s and P-39s...luvz me mah trikes!
> 
> From what I understand, the 39s were "tweaked" by the Russians by removing the outboard MGs to increase the roll rate. Other than that, they were pretty much standard. They used them with great success even past the middle of the war, against German fighters. The 39 started out getting a "bum rap" in the US when it got the reputation for being squirrely and going end over end at times. It was found that the CG went too far to the rear unless the plane was flown with a full ammo compartment in front. After that, they carried at least the weight of a full load of spent shell casings up front, and the stability problems went away. The plane was a favorite of the Russians (and was hated by the Germans) for a reason.
> 
> ...



There was a similar exercise done with motor sport. They took a group of top "gamers" at internet F1 games and sent them to a racing school. All of them did better than average members of the public but the fastest had also had previous car racing experience. 

There have been cases which have actually done the movie scenario of a passenger in a Cessna being "talked down" and landing the plane when the pilot was incapacitated, however a fully qualified pilot on such a type has almost no chance of being "talked down" on a big civil airliner, it has been tried on simulators.

In automotive terms the video shows that someone can drive a car around town without killing themselves just from internet experience, it is no evidence that they can line up on the grid with Lewis Hamilton after 200 hrs further training.


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## varsity07840 (Feb 8, 2018)

Greg Boeser said:


> Some of the problem with the P-39 in North Africa is it was recognized as obsolete and the pilots flew them accordingly.
> In the Pacific, the P-39 was rated better than the P-40 by those who flew them, but we are comparing P-40E to P-39D in Pacific vs P-40F vs P-39D in North Africa. The Merlin did give the P-40 an advantage over the P-39.


The P-39 was flown gingerly by some pilots because of it's tricky handling characteristics and a CG sensitive to fuel and ammo expenditure. Aside from Wagner's comparison in favor of the P-39 over the P-40 by a margin of 10%, which is marginal at best, I don't recall ever reading a pilot's preference for the P-39 in combat. Certainly, there were a number of P-40 aces in the SWPA as opposed to
perhaps one (Falletta?) in P-39s.

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## ODonovan (Feb 8, 2018)

gumbyk said:


> You don't three-point a nose-wheel aircraft - that's a recipe to end up with only two wheels left on the aircraft. I'd much rather see a heavier landing on the mains first than a flat three-pointer.





MIflyer said:


> "Manages a three pointer" HA! A three pointer in a tricycle gear airplane is NOT a good thing. Any idiot can drive one into the ground and let the landing gear soak up the impact - although it is done pretty often even by people who should know better. A proper landing is to alight on the MLG and then let the nose gear come down. A three pointer is fine on a taildragger - a lot better than hitting on the tailwheel and letting the main gear slam down.
> 
> The nose gear on a Cessna 150, for example is really pretty flimsy, as they say, "keeps the prop from hitting the ground when it is parked."




So, you'd rather have seen him, for his VERY FIRST TIME IN AN AIRCRAFT, be a lawn dart and crash? If you've ever seen someone come in tail heavy on a trike, bounce the tail off the ground, slam the nose gear in so it collapsed, then flip the aircraft, you might be a LITTLE less "know it all" about it. He came in straight and level for his first time flying, EVER. Could you guys have done so well, your first time in an aircraft? I think not. By the way, he didn't flare and land the aircraft. If you had watched the video, you would see the PROFESSIONAL PILOT actually did the flare and touchdown. YOU'RE BUSTED!



-Irish

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## pbehn (Feb 8, 2018)

ODonovan said:


> So, you'd rather have seen him, for his VERY FIRST TIME IN AN AIRCRAFT, be a lawn dart and crash? If you've ever seen someone come in tail heavy on a trike, bounce the tail off the ground, slam the nose gear in so it collapsed, then flip the aircraft, you might be a LITTLE less "know it all" about it. He came in straight and level for his first time flying, EVER. Could you guys have done so well, your first time in an aircraft? I think not. By the way, he didn't flare and land the aircraft. If you had watched the video, you would see the PROFESSIONAL PILOT actually did the flare and touchdown. YOU'RE BUSTED!
> 
> 
> 
> -Irish


Unfortunately I have grown up and grown old with the internet, Just because someone says they have no experience doesn't make it a fact. Every day my television has shows of dancers and singers becoming "brilliant" after little training, it invariably turns out they have private coaches or even went to schools for years.


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## ebergerud (Feb 8, 2018)

US pilots in the PTO called the P39 the "Iron Dog" - it was not a term of affection. There was very little combat between P-39s and Zeros or Oscars. In 1942 beggars couldn't be choosers and the US did have some P-39s to send to Oz and then to Port Moresby. If raided at Moresby by Zeros from Lae, the Japanese obviously had to come over the Owen Stanleys - that meant if 39s came up to fight, they were looking up: very bad. If bombers came to raid the 39s couldn't make the high altitudes the IJ planes usually dropped from. So the 39s would fly out sea and avoid being targets. Some US pilots called units the "Fishing Fleet." I kept my eyes open for a P-39 ace in the PTO and I don't think I found any. (Wikipedia claims there was one 39 ace. I checked their squadron records and they did not have many kills. But again, there simply wasn't that much combat.) Oz pilots were not given P-39s so they did better at Moresby with P40Es in early war. There was a squadron of P-400s at Guadalcanal. They did down a handful of Zeros because Japanese fighters would often end up low after a dog fight and then strafe Marine positions on the ridgelines around Henderson. But Henderson based 39s did not try to climb and join normal festivities - no pilot wanted to fight looking up and double that in a 39.
There were potential fixes for the 39 considered (how about a turbo, like 38s?) but its real problem was its low range. So it took on utility duties for the US and its minor allies - Free French and "our" Italians flew them. On paper the King Cobra (P-63 as I recall) was a fine plane, but had such short legs all went to the USSR. 
Russians had a lot to like in the 39. All American planes were rugged and the Allison was reliable. Tricycle landing gear was a better system if you were willing to accept the weight trade-off. Even with multi-caliber armament, the 39 could put out a lot of lead in a strafing attack. I read that Soviet pilots believed the 39 deterred head-on attacks by LW planes. The ballistics on the 37mm was poor, but image what would happen if you got hit with one in a "header"? And if the thing didn't jam, and a pilot was a decent shot, that cannon would have damaged or destroyed almost any German vehicle or AFV. As I recall however, Soviet fighter pilots strafed but rarely carried bombs figuring the common IL2 was a better choice. The Russians had P-40s, Hurricanes and Spit Vs and used them all. (Lord they were using I-16s in 1942.) But 39s were part of the armada until 1945. Do recall that until 1991 Soviet sources were very reluctant to say anything good about Lend Lease, but they praised the 39 even during the Cold War. The Russians must have liked it. So maybe Yeager was right about the 39s good qualities.

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## swampyankee (Feb 8, 2018)

ebergerud said:


> US pilots in the PTO called the P39 the "Iron Dog" - it was not a term of affection. There was very little combat between P-39s and Zeros or Oscars. In 1942 beggars couldn't be choosers and the US did have some P-39s to send to Oz and then to Port Moresby. If raided at Moresby by Zeros from Lae, the Japanese obviously had to come over the Owen Stanleys - that meant if 39s came up to fight, they were looking up: very bad. If bombers came to raid the 39s couldn't make the high altitudes the IJ planes usually dropped from. So the 39s would fly out sea and avoid being targets. Some US pilots called units the "Fishing Fleet." I kept my eyes open for a P-39 ace in the PTO and I don't think I found any. (Wikipedia claims there was one 39 ace. I checked their squadron records and they did not have many kills. But again, there simply wasn't that much combat.) Oz pilots were not given P-39s so they did better at Moresby with P40Es in early war. There was a squadron of P-400s at Guadalcanal. They did down a handful of Zeros because Japanese fighters would often end up low after a dog fight and then strafe Marine positions on the ridgelines around Henderson. But Henderson based 39s did not try to climb and join normal festivities - no pilot wanted to fight looking up and double that in a 39.
> There were potential fixes for the 39 considered (how about a turbo, like 38s?) but its real problem was its low range. So it took on utility duties for the US and its minor allies - Free French and "our" Italians flew them. On paper the King Cobra (P-63 as I recall) was a fine plane, but had such short legs all went to the USSR.
> Russians had a lot to like in the 39. All American planes were rugged and the Allison was reliable. Tricycle landing gear was a better system if you were willing to accept the weight trade-off. Even with multi-caliber armament, the 39 could put out a lot of lead in a strafing attack. I read that Soviet pilots believed the 39 deterred head-on attacks by LW planes. The ballistics on the 37mm was poor, but image what would happen if you got hit with one in a "header"? And if the thing didn't jam, and a pilot was a decent shot, that cannon would have damaged or destroyed almost any German vehicle or AFV. As I recall however, Soviet fighter pilots strafed but rarely carried bombs figuring the common IL2 was a better choice. The Russians had P-40s, Hurricanes and Spit Vs and used them all. (Lord they were using I-16s in 1942.) But 39s were part of the armada until 1945. Do recall that until 1991 Soviet sources were very reluctant to say anything good about Lend Lease, but they praised the 39 even during the Cold War. The Russians must have liked it. So maybe Yeager was right about the 39s good qualities.




I wonder if people are ignoring a possible explanation for the poor repute of the P-39 in the Pacific: the Japanese combination of pilots and aircraft was better than the Luftwaffe.

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## FLYBOYJ (Feb 8, 2018)

ODonovan said:


> That's not ENTIRELY true. Check out the guy in the first vid. He even sticks a three pointer. Luvz me mah trikes!


The OP on this was comparing flying a high performance WW2 fighter to a game flight simulator. You show two clips where 2 "sim" pilots completed 2 landings (at least one admitted that he didn't complete the full landing) in a very light, GA aircraft that were designed for training and to be as forgiving as possible, let alone with an instructor in the next seat. I'm a flight instructor and had folks with no flight experience landing within their first hour, some people have do the knack, but there is about no chance in hell you're going to see a gamer do that in say a P-39, let alone any WW2 tail dragger fighter aircraft! What is not shown is if the instructor(s) were inputting rudder corrections or tapping the bottom of the yoke as a prompt. With all this said, you're comparing apples with oranges and grapes. Take the same zero time gamer and put him in a high performance aircraft, the results will not be as pleasant and if they are in a two place aircraft, the IP better be on his top game combined with balls of steel.



ODonovan said:


> So, you'd rather have seen him, for his VERY FIRST TIME IN AN AIRCRAFT, be a lawn dart and crash? If you've ever seen someone come in tail heavy on a trike, bounce the tail off the ground, slam the nose gear in so it collapsed, then flip the aircraft, you might be a LITTLE less "know it all" about it.
> -Irish


I've seen it lots of times and actually prevented it from happening a few times - and you're also talking to some folks that have more time flying real aircraft than you have behind your monitor and tabletop joystick. I recommend you cool your jets.

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## Greg Boeser (Feb 8, 2018)

Part of the poor repute came from the fact that many of the pilots flying them were right out of flight school with zero time in fighters. Combine this with abysmal facilities and non-existent supplies. Front line units had serviceability of less than %50 most of the time. This was theater wide, not just P-39 units. Pilots preferred the P-400s because the 20mm was more reliable than the 37mm, and the oxygen systems were scavenged from wrecked P-39s to allow them to function above 13000 ft. as better aircraft arrived in theater, the P-39s were quickly relegated to ground support and convoy patrol duty. That their weren't a lot of aces is no surprise. The best pilots were quickly transferred to the P-38 squadrons.

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## FLYBOYJ (Feb 8, 2018)

Greg Boeser said:


> Part of the poor repute came from the fact that many of the pilots flying them were right out of flight school with zero time in fighters. Combine this with abysmal facilities and non-existent supplies. Front line units had serviceability of less than %50 most of the time. This was theater wide, not just P-39 units. Pilots preferred the P-400s because the 20mm was more reliable than the 37mm, and the oxygen systems were scavenged from wrecked P-39s to allow them to function above 13000 ft. as better aircraft arrived in theater, the P-39s were quickly relegated to ground support and convoy patrol duty. That their weren't a lot of aces is no surprise. The best pilots were quickly transferred to the P-38 squadrons.


Don't forget tactics.

The P-38 didn't reach theater until late 1942. For the most part the best pilots didn't transfer to P-38 squadrons, whole squadrons and groups converted when the P-38 became available.

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## Greg Boeser (Feb 8, 2018)

True, but those squadrons and groups were often brought up to full strength by cherry picking the other squadrons in theater.
You want your best flying your best.


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## XBe02Drvr (Feb 9, 2018)

FLYBOYJ said:


> I'm a flight instructor and had folks with no flight experience landing within their first hour, some people have do the knack


Back in my instructing days I found that if carefully prepared, about one student in 10 could make the very first landing of their first lesson unassisted by me except for intensive coaching. When an unsure, not very confident student realizes what he/she has just accomplished on the very first lesson, it comes as an earth-shaking epiphany and a powerful motivator.
Cheers,
Wes

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## Peter Gunn (Feb 9, 2018)

XBe02Drvr said:


> Back in my instructing days I found that if carefully prepared, about one student in 10 could make the very first landing of their first lesson unassisted by me except for intensive coaching. When an unsure, not very confident student realizes what he/she has just accomplished on the very first lesson, it comes as an earth-shaking epiphany and a powerful motivator.
> Cheers,
> Wes



Well said Wes, some things you never forget, the first solo, first landing, first kiss, first ride in a '67 Stingray (427 C.I.D. w/3x2 Carbs) etc.

After my first landing I was all "YES!!!" swelling with pride/euphoria... then about fell over when I got out as the rush subsided. But man that sense of accomplishment!


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## Stig1207 (Feb 9, 2018)

swampyankee said:


> I wonder if people are ignoring a possible explanation for the poor repute of the P-39 in the Pacific: the Japanese combination of pilots and aircraft was better than the Luftwaffe.



The 81st FG lost more P-39's in one engagement with Jg 77 than EA kiils they were credited with in the entire period they flew in the MTO.


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## FLYBOYJ (Feb 9, 2018)

Stig1207 said:


> The 81st FG lost more P-39's in one engagement with Jg 77 than they were credited with in the entire period they flew in the MTO.


I found reference to this at several locations, this citation is not completely accurate as several squadrons make up a fighter group.

The 91st, 92nd and 93rd FS made up the 81st FG. Rather than identifying the actual squadrons, many authors list the whole group as the participant when if fact it may be one squadron (and it probably was).

I found reference where in March 1943 7 out of 12 "81st FG" P-39s were shot down, possibly by JG 77 Me 109s. The P-39s were being escorted by RAF Spitfires (Fighters over Tunisia)

_81st Fighter Group, 350th Fighter Group and two squadrons of the 68th Observation Group in North Africa, coming into action by the end of 1942. All of these units struggled to find a full complement of aircraft during the fighting in North Africa, and also struggled against the Luftwaffe. *During the fighting in North Africa and Italy the USAAF lost 107 P-39s, most of them lost to ground fire while undertaking ground attack missions. In return the P-39 pilots scored twenty confirmed aerial victories and destroyed a similar number of aircraft on the ground,* but their main role by now was no longer as a air superiority fighter. The final aerial victory for a USAAF P-39 probably came on 6 April 1944._
*
Bell P-39 Airacobra in American Service*

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## doc_nele (Feb 9, 2018)

Hi everyone. I have read Alexadar Pokriskhin's memoirs, and he basically found his "Bucephalus" in P-39 (he flew an all-up P-39N with all weapons wired to one trigger). The true value is that he used its strong points and advanced tactics. Values were above average armament, radio equipment, adequate performance in combat. Advanced tactis were many, including use of radar situation information (yes, Soviets used radars!), high crusing speed (resulting in much reduced engine lifetime), constant climbing and shallow diving while cruising (up to compressibility point). Served his squadron well until the end of war (it was still frontliine fighter of his unit in Germany, based on a section of Autobahn serving as an airstrip).

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## michaelmaltby (Feb 9, 2018)



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## pbehn (Feb 9, 2018)

doc_nele said:


> Advanced tactis were many, including use of radar situation information (yes, Soviets used radars!), high crusing speed (resulting in much reduced engine lifetime), constant climbing and shallow diving while cruising (up to compressibility point).QUOTE]
> In general, there were many pilots practices that resulted in reduced engine lifetime, none so much as getting shot down, though.


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## Greg Boeser (Feb 9, 2018)

FLYBOYJ said:


> I found reference to this at several locations, this citation is not completely accurate as several squadrons make up a fighter group.
> 
> The 91st, 92nd and 93rd FS made up the 81st FG. Rather than identifying the actual squadrons, many authors list the whole group as the participant when if fact it may be one squadron (and it probably was).
> 
> ...


13 March, 1943
Ten P-39s from 93rd Squadron and two from 91st engaged in a strafing mission over La Fauconnerie were bounced by a large formation of JG 77 Bf 109s led by Major Muenchenberg. The Germans claimed 13 kills between seven pilots, The 81st lost seven a/c, with six pilots becoming POWs and one evading back to friendly lines.

source: _A History of the Mediterranean Air War 1940 - 1945, _Shores, et al.

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## gumbyk (Feb 11, 2018)

ODonovan said:


> So, you'd rather have seen him, for his VERY FIRST TIME IN AN AIRCRAFT, be a lawn dart and crash? If you've ever seen someone come in tail heavy on a trike, bounce the tail off the ground, slam the nose gear in so it collapsed, then flip the aircraft, you might be a LITTLE less "know it all" about it. He came in straight and level for his first time flying, EVER. Could you guys have done so well, your first time in an aircraft? I think not. By the way, he didn't flare and land the aircraft. If you had watched the video, you would see the PROFESSIONAL PILOT actually did the flare and touchdown. YOU'RE BUSTED!
> 
> 
> 
> -Irish


I've pulled too many aircraft off the runway with a collapsed nosewheel after this sort of landing to accept that it is a good way of landing, regardless of experience level.


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## XBe02Drvr (Feb 11, 2018)

gumbyk said:


> I've pulled too many aircraft off the runway with a collapsed nosewheel after this sort of landing to accept that it is a good way of landing, regardless of experience level.


My girlfriend watched her favorite airplane in the world, the one she took her Private Pilot checkride in, a Beech Sundowner, make a solid, level attitude three-point landing, then crow-hop off the runway to wind up in a heap in the grass. This due to the ham-fisted efforts of a newly retired full bird Colonel B-52 driver with 10K hours in heavy iron.
Incidentally, both mains and one wing failed laterally, but the nosewheel stayed intact!
Cheers,
Wes


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## XBe02Drvr (Feb 11, 2018)

ODonovan said:


> Could you guys have done so well, your first time in an aircraft? I think not. By the way, he didn't flare and land the aircraft. If you had watched the video, you would see the PROFESSIONAL PILOT actually did the flare and touch


A number of my students over the years have done BETTER than that on their very first flight, making their very first landing entirely unassisted on the controls, albeit with some verbal coaching. And as for the instructor "doing the flare and landing", it wasn't quite like that. Been there, done that. Thousands of times. I can tell when the instructor "took over"; more like "helped out". That happened just before touchdown after the student had set up the flare but wasn't bringing the nose up far enough to curtail the rate of descent. The instructor applied just enough back pressure to prevent a nose plant. This student obviously wasn't yet comfortable with the ailerons; witness the wing rocking going on right down practically to touchdown. That instructor's got bigger cajones than I. I wouldn't get into landing until my student had gotten over that wing-rocking nervousness, 15 or 20 minutes at most.
Cheers,
Wes


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## P-39 Expert (May 21, 2018)

swampyankee said:


> I wonder if people are ignoring a possible explanation for the poor repute of the P-39 in the Pacific: the Japanese combination of pilots and aircraft was better than the Luftwaffe.


Absolutely. Add to that the US radar would not be in theater until August '42. Just two squadrons of P-39s initially. No plane on earth at that time could intercept bombers between 18-22000' from the ground. They had to have early warning but since there was no radar yet they had to fly patrols and only a couple of planes could be spared at any one time. First contact was 4/30/42 followed by multiple raids daily. With adequate warning the P-39s could (and did) get up to 23000' to intercept the bombers, but they were still outnumbered and very green. They did pretty well considering.

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## Clayton Magnet (May 22, 2018)

MIflyer said:


> I have played a bit with flight simulators and had a lot of fun with Secret Weapons of the Luftwaffe. And I can tell you there is NO connection between flying computer games and the real thing.


I would say that computer flight sims have changed a bit in the 25 years since Secret Weapons of the Luftwaffe was released.

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## FLYBOYJ (May 22, 2018)

Clayton Magnet said:


> I would say that computer flight sims have changed a bit in the 25 years since Secret Weapons of the Luftwaffe was released.


Unless they changed enough to provide full movement, simulated pilot g loading and no synthetic latency, they are still nothing but toys.

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## GrauGeist (May 22, 2018)

Sims have certainly come a long way since the 80's/90's, but still cannot provide all the sensory input that a person encounters while flying (or driving).

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## MIflyer (May 22, 2018)

"...but still cannot provide all the sensory input that a person encounters while flying."

Nor do you get scared when you hear an airplane announce as inbound, reporting the same place you are, and you can't find him.

I recall once in particular being about to report I was over the Thomas Bridge at LA Harbor, and hearing another airplane announce as being over the same bridge. Then I looked over and saw I was basically flying formation with a red and orange T-6. I reported I was over the bridge too and had the T-6 in sight.

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## Clayton Magnet (May 22, 2018)

I would never suggest it is a potential replacement for actual training. However, to suggest they can play ZERO role is flight training is also incorrect. When I was doing my private license training 20 years ago, my flight school had a few open desktops with whatever the latest Microsoft Flight Simulator installed. We were encouraged to play around with the program, and specifically work on our VOR skills.

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## gumbyk (May 22, 2018)

Clayton Magnet said:


> I would never suggest it is a potential replacement for actual training. However, to suggest they can play ZERO role is flight training is also incorrect. When I was doing my private license training 20 years ago, my flight school had a few open desktops with whatever the latest Microsoft Flight Simulator installed. We were encouraged to play around with the program, and specifically work on our VOR skills.



They CAN play a small role in flight training - as a procedures trainer, which is what you were working on. Even having posters of hte cockpit layout is an aid to training. But they are just that - a training aid, for a very specific part of the training, which isn't what was shown on the video.

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## DarrenW (May 22, 2018)

swampyankee said:


> I wonder if people are ignoring a possible explanation for the poor repute of the P-39 in the Pacific: the Japanese combination of pilots and aircraft was better than the Luftwaffe.






P-39 Expert said:


> Absolutely. Add to that the US radar would not be in theater until August '42. Just two squadrons of P-39s initially. No plane on earth at that time could intercept bombers between 18-22000' from the ground. They had to have early warning but since there was no radar yet they had to fly patrols and only a couple of planes could be spared at any one time. First contact was 4/30/42 followed by multiple raids daily. With adequate warning the P-39s could (and did) get up to 23000' to intercept the bombers, but they were still outnumbered and very green. They did pretty well considering.



I agree that on the whole Japanese pilots were a very aggressive lot that fought with a lot of tenacity and vigor, rarely "bugging out" when the going got tough for them. This made them a very difficult enemy to defeat because you'd more often than not have a fight to the death on your hands, regardless if he had sufficient stick time to be fully proficient at his trade. The problem is that the Luftwaffe has been held in such high regard by postwar authors that it's extremely hard to separate the legend that was created from actual reality.....

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## DerAdlerIstGelandet (May 22, 2018)

FLYBOYJ said:


> Unless they changed enough to provide full movement, simulated pilot g loading and no synthetic latency, they are still nothing but toys.



Don’t forget authentic sound, vibrations, weather effects...

As a crew member, private pilot and former maintainer, I will never agree that your average sim is anything more than a game. Full motion commercial flight sims are a different thing though. There is a reason you can log sim time for IFR training.

Speaking of full motion flight sims though, I have one hour booked in a 737-800 full motion sim with flight instructor this weekend.

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## FLYBOYJ (May 22, 2018)

Clayton Magnet said:


> I would never suggest it is a potential replacement for actual training. However, to suggest they can play ZERO role is flight training is also incorrect. When I was doing my private license training 20 years ago, my flight school had a few open desktops with whatever the latest Microsoft Flight Simulator installed. We were encouraged to play around with the program, and specifically work on our VOR skills.


And I've used them for my instrument rating and when working on y CFII and they were great for precision flying "by the numbers" but to believe that you're going to determine how a high performance aircraft is going to perform during simulated combat conditions is ridiculous.


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## XBe02Drvr (May 22, 2018)

DerAdlerIstGelandet said:


> Speaking of full motion flight sims though, I have one hour booked in a 737-800 full motion sim with flight instructor this weekend.


My girlfriend, who's had one initial and three recurrent training sequences in those (737-800) at American, says you'll never mistake it for real flight, but it'll still make you sweat. She says it's faithful to reality except in situations where complicated transitions and interactions are happening together, such as flare to landing. Then the computer gets a little bit overloaded with all the motion calculations and lags slightly behind the pace of events, such that the same flare technique that gets you a greaser in the plane will give you a thump in the sim. And if you master greasers in the sim, be ready for a rude shock in the plane.
Cheers,
Wes

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## parsifal (May 22, 2018)

On paper, P-39 exchange rates in the air with A6M looks quite favourable. Unfortunately most accounts are based on post war claims data by the US forces, which ended up being summarised in the USSBS. Problem is, the claims, like all claims data is generally wildly inaccurate. As an example, the first raid in which P-39s rose to fight A6Ms over Moresby occurred May 9 1942. I don't think there was a combat between A6Ms and P-39s before that date in this TO. Allies claimed three A6Ms downed for no losses in the air. problem is, there were no losses to the A6Ms, not even a scratch. this kind of inaccurate reporting continued for the entire first deployment of the 8FG to the end of July.

To be fair, I don't think it was the aircraft mismatch alone. Average approach altitude for the IJA bombers was 24000 feet, coming in over the owen Stanleys. Because of those mountains, early warning until the end of 1942 in this TO was limited to about 40miles. there wasn't time for the P-39s to reach them, and even them at 24k the p-39s handled like pigs, hence their nickname. Most days the p-39s just took off in the opposite direction....better to be airborne and out of harms way than airborne targets I guess.

The second unique factor to consider at this time was the quality of the pilots. it was the tainan air gp, including the famous lae wing. Lae Wing included such greats as Sakai and nishizawa. In the whole of 1942, only two pilots of this super elite group were lost in the air (according to one source at least...put it this way, there were just 15 a/c and about 39 pilots, and nearly all of these guys fought on in later campaigns. in 1943-4, where the wing member did suffer a lot more fatalities. .For 1942, there were other losses over moresby which I haven't tallied from Rabaul.

For me guys, claiming the p-39 was fully the equal to the A6M over port morersby does not hold up to scrutiny.

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## Greg Boeser (May 22, 2018)

Have you read_ Eagles of the Southern Skies?_
Ruffato does a pretty good job corroborating allied and Japanese claims during April to November 1942.
The first encounter with P-39s occurred on 6 April 1942. The Japanese claimed 2 P-39s and three other fighters for no losses, and did get 2 RAAF Kittywawks, but no P-39s. 
The first Airacobra kill vs a Tainan Zero occurred on 30 April 1942, near Lea (FPO2c Izumi Hideo KIA), and the first kill over Port Moresby occurred the following day when Lt Don McGee bounced FPO2c Arita Yoshisuke while strafing. 
Ruffato compares claims and losses day by day for the Tainan AG and their opponents to build a more accurate picture of the air fighting over New Guinea and Rabaul during the tenure of the Tainan AG. Based on reported losses, the Tainan shot down 81 a/c of all types over New Guinea and the Bismarck Archipelago, losing 42 pilots to all causes. This does not include fighting in the Solomons.

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## parsifal (May 23, 2018)

Tainan AG after its deployment to 17AA command in NG initially concentrated its aircraft at Lae to prosecute the Australian and American forces stationed at Moresby. Between April and July, the Tainan Air Group flew 51 missions, totalling 602 sorties. Not all of these were offensive and not all the missions that were offensive were flown against moresby. According to the translated version of Hata, during this time, the unit claimed to have destroyed 300 enemy aircraft, an obviously far fetched number. The Tainan's losses were 20 aircraft, however the majority of these losses were either from ground fire or due to non-operational losses, like getting lost, About half those pilots were killed. Replacement aircraft gave the unit a total of 24 Zeros by August 1942, flown by 55 pilots. Because of the surplus in aircrew, only the most experienced pilots were allowed to fly combat missions. There were virtually no losses in actual air combat to allied units until very late in 1942, notwithstanding the source material that you are quoting..

As I said the majority of loss reports in nearly every western book written on the subject are massively flawed for the simple reason they accept, lock stock and barrel the claims based figures of the reports done at the time. At the end of the war, the USN (and I think the USAAC) conducted a detailed survey of losses, weeding out some of the more obvious errors from the wartime daily returns but retaining the same basic flaw….they rely on one side’s only loss reports. Because the japanese never did get around to publishing their own loss reports, many authors think its okay to do that. I don’t.

Hata, Ikuhiko; Yasuho Izawa (1975 (original) 1989 (translation)). Japanese Naval Aces and Fighter Units in World War II. Translated by Don Cyril Gorham. Annapolis: US Naval Institute Press


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## Peter Gunn (May 23, 2018)

OK, you guys have me confused (not hard to do really but still...) so what did happen over Port Moresby in 1942? Is there a reasonable set of numbers for aircraft lost for both sides that can give me a better picture of the whole year? As a kid I read that terrible Caiden book about Sakai, as I got older I realized how much fiction that was, but I still want a better picture of what happened. So any info or references you can give I'd greatly appreciate.

Thanks

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## P-39 Expert (May 23, 2018)

parsifal said:


> On paper, P-39 exchange rates in the air with A6M looks quite favourable. Unfortunately most accounts are based on post war claims data by the US forces, which ended up being summarised in the USSBS. Problem is, the claims, like all claims data is generally wildly inaccurate. As an example, the first raid in which P-39s rose to fight A6Ms over Moresby occurred May 9 1942. I don't think there was a combat between A6Ms and P-39s before that date in this TO. Allies claimed three A6Ms downed for no losses in the air. problem is, there were no losses to the A6Ms, not even a scratch. this kind of inaccurate reporting continued for the entire first deployment of the 8FG to the end of July.
> 
> To be fair, I don't think it was the aircraft mismatch alone. Average approach altitude for the IJA bombers was 24000 feet, coming in over the owen Stanleys. Because of those mountains, early warning until the end of 1942 in this TO was limited to about 40miles. there wasn't time for the P-39s to reach them, and even them at 24k the p-39s handled like pigs, hence their nickname. Most days the p-39s just took off in the opposite direction....better to be airborne and out of harms way than airborne targets I guess.
> 
> ...


Since this thread is titled "P-39 vs. German Fighters" I have attached a graph of P-39 vs. Zero performance.  Graph is for a P-39K but is almost exactly the same as for the D model. Zero performance is noted by the small black circles.
As the graph shows, the P-39 had a fairly significant speed advantage but the Zero climbed better. Of course the AAF pilots did not know the performance of the Zero until results of tests of the Alaskan Zero were distributed in the fall of '42. 
The little curved line in the climb section between 12500' and 15000' denotes the reduction from 3000rpm (combat) to 2600rpm (max continuous) at the 5 minute mark. The Allison engine was rated at military (combat) power for 5 minutes, so after that time the power was reduced to max continuous for the remainder of the test climb. 
Of particular interest is the P-39 climb rate at 1000fpm with drop tank. As we can see this occurred at about 19000'. The 1000fpm is significant because most observers consider this the operational or combat ceiling since climbing at less than 1000fpm was both dangerous and hard on the engine as it was operating at almost full power.
The Japanese Bettys came in between 18000' and 22000', sometimes a little higher but I have a hard time believing they ever got to 30000'.
So, virtually every combat involved the Japanese having the altitude advantage and the AAF in a defensive posture.
The P-39s (with drop tank) on patrol (since there was little early warning) could (and did) get to 23000' and intercept but it was very difficult.
After sighting the enemy and dropping their tank, climb was much easier. Plus combat climb at 3000rpm was normal since if you were in combat at 3000rpm and you needed to climb you didn't reduce power to 2600rpm. The reduction to 2600rpm was for the performance test. Climb at 3000rpm was pretty close to the Zero climb rate. 
In summary, the P-39 was about 40mph faster than the Zero above 15000' and could climb almost as fast at combat power. Disadvantage was maneuverability and range, with the big disadvantage being the highest cruising altitude with drop tank being below the Bettys and their Zero escort. 
The 5 minute combat power restriction was increased to 15 minutes at mid year '42 along with finally discarding the power robbing port backfire screens. Then by December '42 the P-39N was available which would substantially outclimb the Zero at all altitudes. Just my 2 cents worth.


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## Conslaw (May 23, 2018)

P-39 Expert said:


> Since this thread is titled "P-39 vs. German Fighters" I have attached a graph of P-39 vs. Zero performance.  Graph is for a P-39K but is almost exactly the same as for the D model. Zero performance is noted by the small black circles.
> As the graph shows, the P-39 had a fairly significant speed advantage but the Zero climbed better. Of course the AAF pilots did not know the performance of the Zero until results of tests of the Alaskan Zero were distributed in the fall of '42.
> The little curved line in the climb section between 12500' and 15000' denotes the reduction from 3000rpm (combat) to 2600rpm (max continuous) at the 5 minute mark. The Allison engine was rated at military (combat) power for 5 minutes, so after that time the power was reduced to max continuous for the remainder of the test climb.
> Of particular interest is the P-39 climb rate at 1000fpm with drop tank. As we can see this occurred at about 19000'. The 1000fpm is significant because most observers consider this the operational or combat ceiling since climbing at less than 1000fpm was both dangerous and hard on the engine as it was operating at almost full power.
> ...


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## Conslaw (May 23, 2018)

In the hot and humid conditions that defined the Port Moresby area, the density altitude at sea level could be 5,000 feet. This means a plane flying at 23,000 above sea level might perform like it was flying 5,000 feet higher under standard conditions. That being said, the density altitude was the same for all combatants, so the Japanese planes would be facing the same issue.

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## Greg Boeser (May 23, 2018)

Parsifal,
Ruffato uses the Kodochosho records of all IJN air units in the Southeast Area to make his assessments. He does not rely on just US and Australian wartime claims, but compares claims vs reported losses of both sides, giving a score of claims vs actual losses. You should read it. He's an Italian so has no iron in the fire.

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## parsifal (May 23, 2018)

Some known details of the 8th fighter group in the SWPA

From the Australian @ war research site

35th fighter squadron
The 35th FS sailed to Australia with the rest of the 8th FG on an old cattle boat called "Maui", departing the US leaving late January 1942. They arrived in Brisbane on 6 March 1942.

The 8 FG were equipped with P-39's assembled at Amberley west of Brisbane Brisbane. These P-39's assembled at Amberley were originally intended to go to the Philippines but the convoy was diverted to Brisbane. The 35 FG (not FS) had earlier been equipped with P-39's also assembled at Amberley.

Elements of 35 FS moved to Woodstock just outside of Townsville on 26 April 1942 on their way to Port Moresby, where they arrived on 30 April 1942. They later returned to Woodstock on 29 June 1942 having suffered heavy losses whilst at Moresby for various rest and re-equipment tasks. They relocated to Garbutt, Townsville on 27 July 1942 and then moved to Milne Bay in New Guinea on 18 September 1942.

They relocated to Mareeba airfield on 24 February 1943 after again having suffered further heavy casualties and finally moved to Port Moresby in New Guinea on 10 May 1943.

"Eagle Farm 1942 - Airacobra Assembly" by Brian Creer (note these Airacobra's were actually assembled at Amberley airfield)

36th Fighter (Pursuit) sqn)

The 36th FS of the 8th FG of the USAAC arrived in Brisbane on 6 March 1942.

They moved to Lowood A/B (an RAAF training field about 60kms west of Brisbane) on 13 March 1942. They relocated to Antill Plains airfield near Townsville on 4 April 1942 where there were 2 landing strips.

They moved to Port Moresby, arriving on 26 April 1942 (another source gives the date as 30 Apr 42). They later returned to Townsville having also suffered more than 50% losses whilst engaged area on 30 June 1942 for various rest and re-equipment tasks. 

The History of the 36th Fighter Squadron shows that ground elements of the 36th Fighter Squadron arrived back in Townsville on the ship Tasman on 30 June 1942. They boarded a train and were taken to Antil Plains airfield (20km south of Townsville). They boarded trucks and were taken to the camp formerly occupied by the 40th Squadron. They were met by the pilots and the men who had returned from Port Moresby by air transport and the men who had been on duty at Horn Island since 1 April 1942. The 36th then moved to Ross river Airfield, Townsville arriving there on 2 August 1942 where they used the new runway that was nearing completion on the edge of Townsville.

They moved to Milne Bay in New Guinea on 18 September 1942. On 22 February 1943 they moved to Mareeba airfield in north Queensland and moved to Port Moresby in New Guinea on 22 May 1943.

80th Fighter Squadron
The 80th FS moved to Lowood near Townsville on 28 March 1942 (another source shows the date as 13 Mar 42). By 10 May 1942, the 80th Pursuit Squadron had moved from Lowood to Petrie just north of Brisbane where they trained for combat for 2 months. 

They moved to Port Moresby, arriving on 20 July 1942. They relocated to Milne Bay on 8 November 1942. They moved to Mareeba airfield on 6 February 1943 to re-equip with P-38 Lockheed Lightnings. They then moved to Kila airfield at Port Moresby on 21 March 1943.

On 20 July 1942 twelve P-400's of the 80th flew to 7 Mile air field outside Port Moresby, New Guinea. They participated in missions to Buna strafing Japanese barges, intercepting Japanese aircraft, escorting Douglas A-24 divebombers to Buna, and escorting transport and bombing missions in the Buna and Kokoda Trail areas, carrying out dive-bombing missions at Myola Lake.

On 15 May 1942 the designation of Pursuit Group changed to Fighter Group.

By 10 November 1942, the 80th FS moved from Seven Mile to Turnbull Field at Milne Bay where they were employed as escorts for air transport and shipping. Not the mark of an overwhelmingly competitive fighter, by any measure!

On 28 January 1943, the 80th FS was relieved by the 36th FS. On 6 February 1943 the 80th moved to Mareeba in north Queensland. Here they converted from their P-400's to P-38 Lightnings.

The 80th moved back to New Guinea in about March 1943 now with p-38s, , and eventually moved to Borneo, then the Celebes Islands, then the Netherlands East Indies and the Philippines and finally Okinawa on 29 August 1944.

A few of the more well known Aces of the 80th Fighter Squadron were Major Jay T. Robbins (22 confirmed kills) and Major Richard I. Bong (40 confirmed kills). Between them, based on these ‘”confirmed” kills, they had managed to destroy the entire tainan AG severasl times over!!!!!!!! 

There is no possibility that any element of the 8FG ever engaged Zekes before 26 April 1942. They did not enter combat until May 1942 in the defence of Moresby. This matches other sources not so one sided as others are relying on …..

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## Greg Boeser (May 23, 2018)

5 P-39s of the 36th PS arrived at Port Moresby on 5 April 1942, led by Col "Buzz" Wagner as part of the first flexing of USAAF muscle, as it were, along with B-26s of the 22nd BG and B-25s of the 3rd BG. This is attested in several Australian war diaries. Strangely, it is not mentioned in_ Attack and Conquer, _the popular history of the 8th FG by Stanaway and Hickey_._
Two pilots, 1/Lt Louis Meng and 1/Lt Charles Faletta, were airborne the next day when the daily Japanese raid came in. Meng engaged the bombers but did not score. Faletta tangled with Zeroes but made no claims. No. 2 Chutai of Tainan claimed two P-39s, while WO Yoshino Satoshi claimed two kills and FPO2c Tan Yukihisa claimed another. the RAAF lost two Kittyhawks, F/Lt Les Jackson ditching in Bootless Bay and F/O Edmund Johnson bellied into a swamp. Both pilots survived.
6 April 1942 is notable because it was the combat debut for the B-26, B-25 and P-39.

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## parsifal (May 24, 2018)

There aren't any Australian sources that place any USAAC P-39's in operational condition at Moresby in early april. They may have staged there due to mechanical difficulties , though that is pure conjecture on my part. I have no P-39's at Moresby at this time. none that I know of at least. Some sources place an advance force of 5 p-39s at Horn Island (some hundreds of miles to the west of Moresby) from 5 April. These saw no combat that I am aware of and lost at least one of their number to non-operational causes.

From this source on "buzz" wagner deployment to Australia I could find no mention of this advance deployment to Moresby:

1st Lieutenant Boyd D. "Buzz" Wagner, later Lieutenant Colonl Wagner in Australia during WW2

But this web page did include reference to a report he made concerning the P-39.

"In May 1942, Lt. Col. Boyd "Buzz" Wagner forwarded a report "Fighter Aircraft Report to USAFIA, 21 May 1942" to the Commanding General USAFIA on the P-39 Airacobra. Wagner criticized their low rate of climb and excessive wing loading, which precluded aerial combat with the Zero. He also criticised the vulnerability of its liquid-cooled engine and its constant problem with the guns jamming. The .30 caliber wing guns and the 37mm propeller-mounted cannon jammed repeatedly. The two cowl-mounted .50 caliber machine guns were the only reliable guns. Wagner felt that the P-39 was _"10 percent better than the P-40 in every respect except maneuverability below 18,000 feet." "
_
A different website on his biography

Boyd D. Wagner Archives - This Day in Aviation


"Lieutenant Wagner was promoted to the rank of Captain, A.U.S., 30 January 1942. On 11 April 1942, Captain Wagner was again promoted, bypassing the rank of Major, to Lieutenant Colonel, A.U.S. He was assigned to the 8th Fighter Group in New Guinea. On 30 April 1942, while flying a Bell P-39 Airacobra, Wagner shot down another three enemy airplanes. In September 1942, Colonel Wagner was sent back to the United States to train new fighter pilots".

Again, no mention of him being deployed to Moresby in early April 1942.


Based on this link

https://buzzwagner.wikispaces.com/file/view/wagner+bio.pdf

Wagner achieved his 8th kill on the 30 April 1942 with the claimed loss of three Japanese aircraft over NG. Between end of December and the end April he had achieved no kills according to this source



This source:

Shadow box

also gives his 5th victory as December 16 1942, then in hospital until the end of april before scoring those 3 "magical" victories on the 30 April. I say magical because I cannot find any corresponding losses from the Japanese units engaged at the time.

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## parsifal (May 24, 2018)

A summary of most of this information can be found at the the pacific Wrecks site

Pacific Wrecks

but it is not complete. You need to access the war diaries by Tatsuo Matsuo and Shindo as well as George henry Johnston “War Diary”….the nearest we have to primary sources

the following raids were recorded over Moresby

*March 31, 1942*
A single G3M piloted by a Lt Harada flew a suicide mission from Lae to Port Moresby, not returning. The attack-bomber made a vertical dive at Waigani Airfield, Port Moresby, and crashed. Seven of the crewmen were discovered and recovered. It was a real suicide dive and crash. The bomber crew's plane was hit on a bombing mission to Clark Field, Luzon in the Philippines, and made a forced landing on the way back on 12 December 1941. They were captured but rescued later when the Japanese occupied the islands, but they were not allowed by the command and were forced to fly suicide missions during the succeeding operations. Ironically, they survived every time they flew. On this date, they determined to kill themselves on a single-plane mission.

War Diary 1942 (see note below) page 46:
Jap Bomber falls to pieces! An extraordinary incident this afternoon. A big Japanese bomber was overhead on reconnaissance in cloudy weather - the same plane that tried unsuccessfully to drop bombs yesterday. None of our fighters went up and the AA never fired a shot, but suddenly the bomber was seen to be falling after losing part of a wing or tail plane. It crashed into the hills in a big cloud of smoke.The bodies of the crew were found in the wreckage - including the body of a high ranking Japanese officer in full uniform and wearing his sword!"

*April 7, 1942 * (Raid 24)
Moresby raided today by Jap bombers and fighters. Several were damaged, but one of our fighters was shot down and another missing. One pilot was saved. Parties looking for Jap pilot who parachuted during Sunday's raid into heavy jungle country.

*April 10, 1942 * (Raid 25)
Seven 4th Kokutai G4M1 Bettys and six Zeros are intercepted by nine 75 Squadron P-40E’s. Lost is a G4M1 piloted by Kobayashi. The bombers were escorted by six A6M2 Zeros. Over the target, intercepted by nine RAAF 75 Squadron P-40E Kittyhawks. Shot down over the Owen Stanley Mountains, going down in a flat spin with smoke streaming from the tail. (verified by 4th Kokutai records according to Shindo)

“War Diary” entry “Apparently as a reprisal for yesterday's raid on Rabaul, seven Jap bombers and six Zero fighters raided Moresby this morning. They dropped their bombs ineffectively when our Kittyhawks tackled them and made off for home at high speed. Our fighters chased them right out of Papua into New Guinea, fighting a series of running dogfights for over half an hour. One Jap bomber was caught in the guns over the terrible jungles of the Owen Stanley Range an went down in a flat spin with smoke streaming from the tail. All our planes got back safely."

*April 17, 1942*
Zeros claimed 6 P-40s destroyed in raid. On the way to the target, A6m2 Zero piloted by Sakai is lost in the Owen Stanley Mountains. Took off from Rabaul on a mission to attack Moresby. On the way to the target over Owen Stanley Mountains, PO2/c Sakai lowered his altitude staggeringly and fell into the jungle after the Zero formation crossed the spine of the Owen Stanley Range, on the south side of the spine. Possibly, this loss was due to an oxygen failure (from Tatsuo Kamino; Winged Samurai, Page 88) In the combats over Moresby RAAF P-40E Kittyhak A29-28 is damaged. No losses to the Japanese according to Tatsuo Kamino.

*April 24, 1942*
In the morning, twelve A6M2 Zeros of the Tainan Kokutai attack Port Moresby, six dog fighting with RAAF 75 Squadron P-40 Kittyhawks and six attacking other aircraft and bombers. They claimed nine shot down (five P-40s, one P-39, two B-26s) and damaged a PBY. In fact, they destroyed two B-26s [one is B-26 “Hello Angel” 40-1448), PBY A-24-5, and 3 x P-40E Kittyhawks RAAF. One further P-40E is damaged. No p-39s were present according to the war diary. 


*April 25, 1942*
Fifteen A6M2 Zeros fly a fighter sweep over Port Moresby. Four strafe 7-Mile Drome. Destroyed on the ground is B-17E 41-2641.

*April 26, 1942*
(Raid 32) 2350-0015GMT/26 Port Moresby area is attacked by nine Type 99 (Nell) heavy bomber with escorting A6M2 Zero fighters approached from north made one run over Kila Drome (3-Mile) at 22000' . Approx. 90 bombs mostly H. E. are dropped near dispersal area. Two 3rd BG A-24s are destroyed one other completely unserviceable. No other damage no casualties. P-40s did not intercept. No record of any p-39 activity 9because they aren’t there yet!!!) The partly completed Rarona (30 Mile Drome) near Galley Reach is also bombed. Reference: Combined Operational Intelligence Centre Log for 26 April 1942 New Guinea Force - HQ & Air via Edward Rogers (He is currently the historian for the 3rd Bombardment Group and is completing work on their WWII history, Harvest Of the grim Reapers vol I - He has also worked with the 40th Fighter Squadron Association to research the histories of their MIA pilots).

*April 28, 1942*
(Raid 33) Six Kittyhawks took off at 1036K to intercept eight Japanese bombers escorted by A6M2 Zeros over Port Moresby. P-40E A29-8 piloted by S/L Jackson and F/Lt B M Cox piloting P-40E A29-47 failed to return. F/Lt Cox listed as missing. F/O Brereton was also wounded in this action, and his aircraft severely damaged, though returned to base. Lost is A6M2 piloted by Yoshimitsu Maeda who later taken POW.

Maeda took off from Lae Airfield on a morning combat air patrol (CAP) and landed safely. Later that same day at 13:00, again took off from Lae along with a Zeke piloted by Arita in pursuit of a “Lockheed Hudson”, in fact B-25C Der SCHpy 41-12496, which was lost, Arita claimed it as shot down, but Maeda did not return and was declared missing. If fact, Maeda became separated, crossed the Owen Stanley Mountains and ended up east of pt Moresby when he spotted a ANGAU ship [MV Laurabada] east of Abau. As he turned to strafe it, and hit a coconut palm on Otamata plantation and made a crash landing in the plantation. Maeda survived the crash landing unhurt but stunned from the impact. He was taken prisoner. The official Japanese report said Maeda was ill due to oxygen starvation, and that is why he made a forced landing. Other reports incorrectly state this Zero was hit by Allied gunfire and the pilot made a forced landing with the engine running at the time.

Returning to Raid 33, one of the Japanese bombers drop four bundles of letters from Australian POWs at Rabaul. The bundles landed near 7 Mile Drome. Three bundles of letters were located and the last bundle was found later. Inside were 395 letters (325 military, 70 from civilians) wrapped in khaki cloth with a 4' streamer attached to each with a message in English "Any person found return to Army Headquarters Port Moresby".

No raids recorded, no losses recorded until May 9th…so much for 3 victories on the 30 april……..

*May 9, 1942*
A6M2 Zeros from the Tainan Kokutai strafe 3-Mile Drome and 7-Mile Drome, damaging several A-24s. It is later cannibalised.

*May 12, 1942 at 0743*
(Raid 46) Eleven A6M2 Zeros strafed Bomana Drome and M. G. positions in area. No damage No casualties. Intercepted by 13 P-39s. claims of two Zeros down. Investigating possible crashes. One P-39 temporarily unserviceable. Two P39's missing. Tatsuo Matsuo or Shindo record any losses to Japanese forces on this day.

0850 Gun on hill behind Bde. H.Q. reports large column Black Smoke 7 to 8 miles on bearing 320 [degrees] and 321 [degrees]
1350 Reported Crash of Aircraft
Paga - Bearing 46 [degrees] - distance 10 miles
Tuaguba - Bearing 44 [degrees] distance 10 miles
1800 1 P39 missing in Raid 46 found at VARI VARI 1 mile inland. Pilot safe. (Reference: New Guinea Force Diary).
(This is the first raid recorded as being intercepted by the P-39s of 8FG)

*War Diary 1942*
This book is the wartime diary of Author George Henry Johnston at Port Moresby. It records his daily notes about happenings, including Japanese air raids and movements of Australia and American forces. The diary is an interesting read, that begins in the darkest days of early 1942 when the Japanese dominated the skies and bombed Moresby daily at will, including the first recorded bombing mission:

_"February 3, 1942 (Raid #1) Six Japanese flying boats bombed Port Moresby 3-3:30am, although no great damage was done this set the stage for the future living conditions in town. One man is KIA."_

The book conveys the feelings of men on the ground who lament about their forgotten status, the "Mice of Moresby" and gripe about when supplies or when P-40 Kittyhawks to defend the town will arrive, dubbed 'Tommorrowhawks' or 'Neverhawks' by the men on the ground awaiting their appearance.

As time progresses, the diary records the changes in the tactical situation: first the arrival of P-40 Kittyhawks of 75 Squadron, that for the first time contest the air raids. Later, the arrival of American reinforcements.

The diary records a tally of air raids against Port Moresby, numbering each raid and providing a summary.

Although some details in the diary have proven to be incorrect with the hindsight of history, it is a compelling look into the day to day lives of men on the ground at Port Moresby.

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## Peter Gunn (May 24, 2018)

parsifal - Once again, many thanks, you've (again) given me some reading material to fill out my knowledge.

*EDIT*
OK, so I'm going through the Pacific Wrecks timeline but it seems I can't get a handle on actual losses from it. I see where sometimes an A6M2 is claimed to be seen trailing smoke in a dive but there isn't corresponding data from the Japanese side for actual losses, although it seems at times there is.

Yeah, I might have to rethink what I wanted to do with this.


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## fiftycal (May 24, 2018)

tomo pauk said:


> There was no belly armor on the P-39.
> In order to compensate for lighter front end, remove the rearmost armor plate (the one behind the oil tank) and replace it with aluminium type. Keep the number of radios to one. Less gun & spent cartridge openings = less drag, so indeed remove the wing guns. Keep the fuel tankage, radius is is already short for Pacific.
> 
> 
> ...



yes there was. i have a pressed inch think belly armor plate off one of my planes


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## fiftycal (May 24, 2018)

the P-39 was not suited to png because of the hot climate and high mountains, but at low level it will run rings around anything except an a6m


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## tomo pauk (May 24, 2018)

fiftycal said:


> yes there was. i have a pressed inch think belly armor plate off one of my planes



Interesting.
Hopefully you will be so kind to post a picture, and/or part number, and/or schematics pertaining the inch-thick belly armor plate that was in series production for a P-39.


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## P-39 Expert (May 24, 2018)

fiftycal said:


> the P-39 was not suited to png because of the hot climate and high mountains, but at low level it will run rings around anything except an a6m


See post #62 this thread.


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## parsifal (May 24, 2018)

Peter Gunn said:


> parsifal - Once again, many thanks, you've (again) given me some reading material to fill out my knowledge.
> 
> *EDIT*
> OK, so I'm going through the Pacific Wrecks timeline but it seems I can't get a handle on actual losses from it. I see where sometimes an A6M2 is claimed to be seen trailing smoke in a dive but there isn't corresponding data from the Japanese side for actual losses, although it seems at times there is.
> ...




Its not the easiest website to navigate, but the information on the known losses is there. sometimes you have to hit the active links to bring up the particulars of a given combat or loss.


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## Greg Boeser (May 24, 2018)

Parsival,
Luca Ruffato relied on the Tainan Kokutai kodochosho as well as those of other units from the Japan Center for Asian Historical Records, not to mention the allied unit records, diaries of combatants from both sides etcetera, for his work. If you want to ignore the official unit records, that's fine. I'll stick with the recorded facts.
You seem to have an axe to grind vis allied kill claims, but seem to accept the Japanese/German claims at face value. What's your beef?
If you haven't read Eagles of the Southern Sky yet, I suggest you do it. The book does it's best to be a sober analysis of the air war over New Guinea during April - November 1942, recording what the combatants claimed and what they reported as their own losses. 
And remember, he is quoting the original sources, not somebody's recollection of what happened forty to fifty years ago, although he does that too for color.

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## Greg Boeser (May 24, 2018)

5 April 1942 - FPO2c Yoshi'e Takuro shot down by F/Lt Les Jackson, 75 Sqn RAAF, NE of Port Moresby, bailed out, MIA.
7 April 1942 - FPO2c Tan Yukihisa shot down by A-24 defensive gunnery, 8th BS, 3rd BG near Lea, KIA.
11 April 1942 - Flyer1c Tanji Jufuku shot down by FO Pete Masters, 75 Sqn RAAF, near Lea, KIA.
17 April 1942 - FPO2c Sakai Yoshimi crashed in mountains after fight with 75 Sqn RAAF. MIA.
28 April 1942 - FPO3c Maeda Yoshimitsu crashed Otonata Plantation while strafing, POW
30 April 1942 - FPO2c Izumi Hideo shot down by 8th FG P-39s near Lea. KIA.
1 May 1942 - FPO2c Arita Yoshisuke shot down by 1/Lt Don McGee, 36th FS, 8th FG over 7 Mile Field, KIA.
2 May 1942 - Flyer1c Kawanishi Haruo shot down near Port Moresby by 1/Lt Don McGee, 36th FS, 8th FG, KIA.
13 May 1942 - FPO3c Honda Toshiaki shot down by 8th FG Airacobras near Lawes Mountain, KIA.
14 May 1942 - FPO1c Oshima Toru collided with 8th FG Airacobra near Port Moresby, KIA.
16 May 1942 - FPO2c shot down near Lea by defensive fire while attacking B-25s of 3rd BG, KIA.
17 May 1942 - FPO2c Ito Tsutomu crashed in mountains returning to Lea after hit by ground fire at 12 Mile Drome. POW
17 May 1942 - LT(jg) Yamaguchi Kaoru crashed into mountains after hit by ground fire at 12 Mile Drome, KIA.
25 May 1942 - Flyer1c Watanabe Masao crashed into sea while attacking B-25s of 3rd BG off Salamaua, probably hit by defensive fire. KIA
29 May 1942 - FPO2c Komori Hisao killed by Australian patrol near Iwaia after forced landing following fight with 8th FG Airacobras. KIA
1 June 1942 - WO Miyakaze Gitaro shot down by Cpt Bill Bennett, 35th FBS, 8th FG near Port Moresby, KIA
9 June 1942 - WO Yoshino Satoshi shot down by 2/Lt Curran Jones, 39th FS, 35th FG near Cape Ward Hunt, KIA
9 June 1942 - FPO1c Kikuchi Sakyo shot down by 2/Lt Dick Suehr, 39th FS, 35th FG near Cape Ward Hunt, KIA
16 June 1942 - Flyer1c Hidaka Takeichiro shot down by 1/LT Francis Royal, 39th FS, 35th FG, near Cape Ward Hunt, KIA
4 July 1942 - Flyer1c Suizu Mitsuo collided with B-26 near Lea, KIA
11 July 1942 - FPO3c Suzuki Matsumi shot down by defensive gunnery from 19th BG B-17s. KIA
20 July 1942 - 4 pilots lost in bad weather between Lea and Rabaul, FPO1c Kobiashi Katsumi, LT(jg) Kurihara Katsumi, FPO2c Miya Unichi, FPO3c Onishi Yoshima MIA
These are the reported losses April - July of the Tainan Group. Credits based on Ruffato's analysis of Allied claims during the period. 
Yes the US and Australians claimed WAAY more than these, but then, so did the Japanese.
Example 9 June 1942 - 22nd BG claimed 11 Zeroes, 35th FG claimed five, and the Japanese claimed four B-26s. Actual losses were 1 B-26 shot down (8 KIA), one force landed at Moresby (repaired/non-operational), one P-39 force landed out of fuel, and two Tainan Zeroes lost with their pilots.

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## parsifal (May 25, 2018)

From Weapon of Denial - Air Power and the Battle for New Guinea, Gary Null 1995; Air force history and museum program
https://media.defense.gov/2010/Oct/06/2001329753/-1/-1/0/AFD-101006-028.pdf

“…….on March 31 U.S. Army Air Forces (USAAF) in the Southwest Pacific Area sent the 8th Bombardment Squadron to assist the small Australian garrison at Port Moresby with some Douglas A-24 dive bombers, the Army’s version of the Navy’s famed SBD Dauntless, which would soon be victorious in the Battle of Midway.

A month later, the 8th Fighter Group arrived, equipped with new Bell P-39 and P-400 Airacobra fighters-the latter export models of P-39s intended for use by the Royal Air Force (RAF). The fighters made their first attacks against Japanese forces 200 miles north of Port Moresby at two sites 19 miles apart on the western shore of the Huon Gulf-Lae, a

major enemy supply base, and Salamaua-on April *30. *On May 15 Port Moresby-bound Australian reinforcements were dispatched”

So this might reveal the mystery of the April 30th combats. However this source again confirms that there were no p-39s present at Moresby 5 april. This source again confirms that they were not present for the whole of april. As previously stated, they may have been deployed at horn Island, in very small numbers. The article does suggest that an attack was carried out at two sites within the huon gulf area, suggesting to me they were ground strikes of some description. 

There certainly weren’t any P-39s at Milne Bay

On Page 10 of the article I found the following: 

“The potential of air attacks against enemy communication lines first became apparent in April 1942. Light bombers began striking Japanese forces on the Papuan peninsula, and by the 30th, twenty-six P-39s of the 8th Fighter Group were strafing aircraft and fuel tanks around Lae and Salamaua.”


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## parsifal (May 25, 2018)

The Japanese losses attributable to 8FG air activity are shown in bold for the date
_5 April 1942 - FPO2c Yoshi'e Takuro shot down by F/Lt Les Jackson, 75 Sqn RAAF, NE of Port Moresby, bailed out, MIA.
7 April 1942 - FPO2c Tan Yukihisa shot down by A-24 defensive gunnery, 8th BS, 3rd BG near Lea, KIA.
11 April 1942 - Flyer1c Tanji Jufuku shot down by FO Pete Masters, 75 Sqn RAAF, near Lea, KIA.
17 April 1942 - FPO2c Sakai Yoshimi crashed in mountains after fight with 75 Sqn RAAF. MIA.
28 April 1942 - FPO3c Maeda Yoshimitsu crashed Otonata Plantation while strafing, POW
*30 April 1942* - FPO2c Izumi Hideo shot down by 8th FG P-39s near Lea. KIA._
Balance this loss against the losses suffered by the P-39s. for example, on 26 April 11 P-39s were ditched and lost whilst enroute to Moresby to relieve 24 sqn RAAF. The book, "Attack & Conquer" indicates on page 310 that eleven aircraft were lost that day with the loss of 2 lives. Other sources indicate that only 9 aircraft were lost and the other six Airacobras that did not turn back all making it safely through to Horn Island. 
_*1 May 1942* - FPO2c Arita Yoshisuke shot down by 1/Lt Don McGee, 36th FS, 8th FG over 7 Mile Field, KIA.
*2 May 1942* - Flyer1c Kawanishi Haruo shot down near Port Moresby by 1/Lt Don McGee, 36th FS, 8th FG, KIA.
*13 May 1942* - FPO3c Honda Toshiaki shot down by 8th FG Airacobras near Lawes Mountain, KIA.
*14 May 1942* - FPO1c Oshima Toru collided with 8th FG Airacobra near Port Moresby, KIA
16 May 1942 - FPO2c shot down near Lea by defensive fire while attacking B-25s of 3rd BG, KIA.
17 May 1942 - FPO2c Ito Tsutomu crashed in mountains returning to Lea after hit by ground fire at 12 Mile Drome. POW
17 May 1942 - LT(jg) Yamaguchi Kaoru crashed into mountains after hit by ground fire at 12 Mile Drome, KIA.
25 May 1942 - Flyer1c Watanabe Masao crashed into sea while attacking B-25s of 3rd BG off Salamaua, probably hit by defensive fire. KIA
29 May 1942 - FPO2c Komori Hisao killed by Australian patrol near Iwaia after forced landing following fight with 8th FG Airacobras. KIA
*1 June 1942* - WO Miyakaze Gitaro shot down by Cpt Bill Bennett, 35th FBS, 8th FG near Port Moresby, KIA
*9 June 1942* - WO Yoshino Satoshi shot down by 2/Lt Curran Jones, 39th FS, 35th FG near Cape Ward Hunt, KIA
*9 June 1942* - FPO1c Kikuchi Sakyo shot down by 2/Lt Dick Suehr, 39th FS, 35th FG near Cape Ward Hunt, KIA_
Sakai gave a fairly interesting account of this loss
P-39 Airacobras in defence of Australia | The Australian War Memorial
_*16 June 1942* - Flyer1c Hidaka Takeichiro shot down by 1/LT Francis Royal, 39th FS, 35th FG, near Cape Ward Hunt, KIA
4 July 1942 - Flyer1c Suizu Mitsuo collided with B-26 near Lea, KIA
11 July 1942 - FPO3c Suzuki Matsumi shot down by defensive gunnery from 19th BG B-17s. KIA
20 July 1942 - 4 pilots lost in bad weather between Lea and Rabaul, FPO1c Kobiashi Katsumi, LT(jg) Kurihara Katsumi, FPO2c Miya Unichi, FPO3c Onishi Yoshima MIA
These are the reported losses April - July of the Tainan Group. Credits based on Ruffato's analysis of Allied claims during the period._
Not all the claims are against Tainan. A good number will have been inflicted on the Chitose AG, which had transferred to Rabaul and also to Gasmata and then to Buna (later in the year). 

_Yes the US and Australians claimed WAAY more than these, but then, so did the Japanese.
Example 9 June 1942 - 22nd BG claimed 11 Zeroes, 35th FG claimed five, and the Japanese claimed four B-26s. Actual losses were 1 B-26 shot down (8 KIA), one force landed at Moresby (repaired/non-operational), one P-39 force landed out of fuel, and two Tainan Zeroes lost with their pilots_.

As indicated above, not all the aircraft listed as a loss are the result of P-39s. Some of the aircraft are not for Zeke pilots though most do appear to be in that category. In that period 26April to 29 June the 8FG was more or less bled white from losses, not sure of its complete loss but above 50%, possibly 25-30 a/c? For this effort they shot down or destroyed on the ground (mostly the latter), 7 enemy a/c, according to this list. AWM is slightly higher at 11 enemy a/c. Perhaps this list is allegedly for Zeke losses, and doesn't include other types, though this seems wrong as well , since i believe "other" losses were a lot more than just 3 or four aircraft.

8FG returned from PNG with virtually no serviceable a/c. Some were repairable, but at least 50% losses amounts to around 30 a/c, for the destruction of just 7 "confirmed" so far. That is not a good exchange rate, and certainly does not show the P-39 as competitive to Zeke. 

.

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## davparlr (May 25, 2018)

I'm about half way through General Kenney's Report, commander 5th AF, up to June, '43. He reports various battles stating losses and victories of air battles and ship attacks. He seems to indicate significant victories over the Japanese, especially number of planes downed by heavy bombers, mainly B-17s with little loss. I suspect his numbers came from crew reports which are suspicious. His reports on shipping, however, should be accurate as they sent reconnaissance flights to verify results. He often mentions the P-39 mainly to get new ones to help replace the old, well used ones. I have not found any particular complaint against the P-39 or P-40, contrary to what was stated in America's Hundred Thousand, and seemed to be happy with them. Once he received a bunch of P-39s but found out they had been written up as performance limited, and thus unusable. He wrote for them to be taken back as useless and ask for P-38s. They later corrected the issue with the delivered P-39s and they were used. It should be noted that many of these battles were against Japans best, not being decimated until the battle of Santa Cruz. The P-38 seems to dominate and certainly would be the plane of choice for this theater of operations.

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## Greg Boeser (May 25, 2018)

parsifal said:


> Not all the claims are against Tainan.


Actually, they are. As of 1 April 1942, the fighter unit of the 4th AG, originally made up of pilots and aircraft of the Chitose AG from the Marshalls, and the Kawai Buntai from Palua (itself made up of pilots from Tainan and 3rd AGs), was amalgamated into the Tainan AG, the main body of which did not arrive at Rabaul until mid-April aboard _Komaki Maru. _The 4th AG fighter unit was originally equipped with A5Ms but these were kept at Rabaul and steadily augmented by Zeroes. By 28 April the Tainan had 24 Zeroes at Lea and eight more at Rabaul, along with six A5Ms. The A5Ms, while scoring some early successes against RAAF Catalinas and Hudsons, were no match for B-17s and B-26s and were withdrawn from front line duties during May.
Nishizawa was part of the 4th AG and scored several kills in A5Ms before the arrival of the Zeroes.
Of note is that no Tainan pilots were lost defending Rabaul, despite numerous claims by bomber gunners.
Between April and November in operations over New Guinea, Rabaul and Northern Australia, 81 Allied aircraft shot down can be directly attributed to Tainan pilots - 17 Kittyhawks/Warhawks, 38 P-39/P-400s, five A-24s, one Hudson, 10 B-25s, 5 B-26s, 5 B-17s.
So, according to Ruffato's analysis the Tainan had roughly a 4:1 advantage over the P-39/P-400 in 1942, 3:1 over P-40s. 5:1 vs allied medium and light bombers, and 5:3 vs B-17s.
Clearly the way to defeat the Zero is with more B-17s.
Significantly, many allied flyers shot down lived to fight another day, whereas the Tainan pilots, eschewing parachutes and radios, ended up dead or captured.

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## Greg Boeser (May 25, 2018)

Greg Boeser said:


> 5 P-39s of the 36th PS arrived at Port Moresby on 5 April 1942, led by Col "Buzz" Wagner as part of the first flexing of USAAF muscle, as it were, along with B-26s of the 22nd BG and B-25s of the 3rd BG. This is attested in several Australian war diaries. Strangely, it is not mentioned in_ Attack and Conquer, _the popular history of the 8th FG by Stanaway and Hickey_._


OK I lied. It is too mentioned in _Attack and Conquer._ Page 33. Falletta and Meng arrived at Port Moresby 6 April with a small contingent of Airacobras. 
Andrew Thomas mentions the April 6 arrival in _Tomahawk and Kittyhawk Aces of the RAF and Commonwealth._
Bruce Gamble in _Fortress Rabaul._
Ruffato specifically cites entries in the 39th and 54th Militia Battalions' logs mentioning the arrival of five Airacobras/P-39s along with the B-25s and B-26s.

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## parsifal (May 26, 2018)

You didn't lie, but I knew it wasn't correct either. But these sources you are quoting don't align with primary data sources like Johnstons war diary. He was there . he says the first of the P-39 groups arrived at the end of April. Wagner, whom you quoted as leading this advance group, had only just been discharged from hospital and was running around the 4 (???) airfields at which 8FG were stationed trying to get the group ready for deployment. It is possible that a small group (probably the five you are referring to) were deployed to horn island at this time (early April), but there are no recorded deployments to the Moresby airfields at this time. I can find only one reference in primary data sources that suggest there might be a deployment to Horn Island, but I don't like to rely on one source unless I have to . There were no USAAC controlled airfields at this time at Moresby, so RAAF records are going to show if they are there. they just aren't there at this time. The RAAF war diary shows them arriving at the end of April. Wagners 3 plane victory 30 april I did eventually track down as a strafing run over one of the auxiliary airfields in the huon Gulf area. They were destroyed as they were attempting to get airborne according to the Japanese ,

8FG performed a vital function don't get me wrong.and later they enjoyed more success. in the finish tainan was defeated. But that wasn't the reason for this discussion. Somewhere in the endless discussions about the aircobra, quite a few have claimed that the P-39 was equal to, or superior to the A6M . But here we have some fairly damning statistics that shows that it wasn't. Moreover we have two leading protagonists, one American, one Japanese, both agreeing that the p-39 was a poor mount.


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## Greg Boeser (May 26, 2018)

39th Bn, stationed at Port Moresby reported on 5 April "A number of new type American planes arrive to carry out bombing operations on Jap Occupied territory. Approx 8 B-26, 5 B-25, 3 B-17, *5 P-39,* 7 P-40 and 6 A-29."
The B-26s belonged to 22nd BG, the B-25s were from 3rd BG, the P-39s were 36th FS, 8th FG, the 7 P-40s were reinforcements for 75 Sqn RAAF, and the A-29s were actually A-24s of 8th BS, 3rd BG.

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## parsifal (May 26, 2018)

39th Bn does not report the presence of these aircraft as confirmed. . They report the expectation of their arrival. Some, including the p-39s never arrived. 

In any event, there is no evidence of their engagement to join the fight until end of April. Some sources say they took no part in the defensive effort until after May 4th. one even suggests it was May 12th before much happened. we do know that the main body of 36th FS was enroute from Townsville to Horn island April 26th, got lost and lost what appears to be either 9 or 11 a/c, and 6 pilots. We know that of the 5 P-39s at Horn Island 5 april (possibly) at least one had been lost in transit. 5 (5April) and 11 (26 April) adds up to 16 a/c, Just about an entire squadron. And at least 12 of them sitting on the bottom of the Coral Sea.

Yeah, P-39s were really effective in the defence of Moresby April 1942...., , .


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## Juha2 (May 27, 2018)

Ah, clearly there were a few P-39s at Port Moresby early in Apr. 1942. Both the monograph based on docus from the both sides and the unit history of the 8th FG quoted by Greg say so. And even the official history of the RAAF mentions, on p. 543, that *on 6 April 42* "..._Operating with the Kittyhawks were two American pilots flying Airacobras (P-39's), the first of a number of American pilots sent to New Guinea to gain combat experience in the area.Each of the Americans scored hits on an enemy bomber_..." Can it be clearer than that?

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## parsifal (May 27, 2018)

well put it this way. Its not relevant to the discussion whichever view is taken. Both sides did not think much of the P-39. Wagner submitted his report in May complaining abut its ineffectiveness, and Sakai in a post war interview expressed surprise that the P-39 that brought down the Zeke being flown by his friend Yoshino could suffer that fate with such an inferior a/c. Sakai put it down to the skill and determination of the American pilot flying on that day

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## Greg Boeser (May 27, 2018)

Jack Jones, the pilot credited with Yoshino's demise would agree. He credits his success with the fact that the P-39s had an altitude advantage diving in on the Zeros which were harrying the B-26s at deck level. Yoshino pulled up in the typical Zero escape maneuver, but Jones' P-39 was able to convert his dive speed into a zoom climb which caught the Zero.
Here is the point where the Tainan's decision not to wear parachutes cost them a great pilot (credited with 15 kills), because, according to Jones, the Japanese pilot was forced out of his burning cockpit but rode the aircraft into the sea. Had he been wearing a parachute, he could have bailed out and been recovered, though the North Coast of New Guinea was a kind of "no man's land" with neither the Australians nor Japanese in firm control outside their scattered bases.

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## fiftycal (May 28, 2018)

P-39 Expert said:


> See post #62 this thread.


sure i will go to the hangar tomorrow afternoon and get a photo, its a bit corroded, but its pressed to be belly shape


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## fiftycal (May 28, 2018)

i had a couple of 8th fg 39's, they flew from moresby, milne bay in late 43 then rotated back to qld and they took new planes up until late 43. i sold one, 41-38385 to hars not long ago, i think they are going to restore it with another one they have, it had kills on it from milne bay and was featured in a bell ad.

when they rotated back the 1st batch of planes were scrapped including the famous "sun setter", and the pilot of -85 (jemison) was killed in tolga qld when he dived -97 into the ground from 8,000ft for no apparent reason

theres a picture on sun setter being scrapped

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## DarrenW (May 28, 2018)

Greg Boeser said:


> Here is the point where the Tainan's decision not to wear parachutes cost them a great pilot (credited with 15 kills)....



So at best Yoshino may have had 4-5 "actual" kills, right? That's if we use a calculation oft performed on this forum, when discussing allied victory credits....

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## XBe02Drvr (May 28, 2018)

DarrenW said:


> So at best Yoshino may have had 4-5 "actual" kills, right? That's if we use a calculation oft performed on this forum, when discussing allied victory credits....


No, no, that only applies to the Allies who are notorious liars and exaggerators, not the Japanese and the Germans, who are universally known to be meticulously accurate in their scoring of kills!!
Cheers,
Wes

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## parsifal (May 28, 2018)

Its not that the Japanese are any better or worse at overclaiming. I happen to think they are worse actually. Its that Allied claims, at least in the PTO were accepted after the war lock stock and barrel (well kinda...there was a recount after the war that revised USN figures substantially downward, but still based on allied claims only) An interim report by Japanese for Japanese was tabled to the USSBS but was not used in the final reports.

Its got nothing to do with whether the allies were inveterate liars or not. Its got nothing to do with the integrity of any of the pilots involved. It has everything to do with our willingness to accept any tripe served up to us by the official histories which milk this mismatch of information . The Germans and Japanese don't cop this criticism, because they don't have an agreedofficial version of history to criticise.

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## Shortround6 (May 28, 2018)

Some of it was blatant overclaiming and some was honest mistakes in the heat of battle. Fired at plane, saw smoke and figured it was damaged/on fire. 
Things can get confusing real quick.
Firefighter story, One of the first times I went in as a nozzle man we entered through the kitchen to attack a couch fire in the living room (Push fire out the front window to save the rest of the house.) Lots of heat and smoke, can't see much more than a dim glow through the smoke. I point the nozzle and open it up and give it a couple of swirls and shut down to see effect. The glow is much smaller so I repeat. Still getting a pulsating red glow through the smoke and steam so I try it again. Still getting that pulsating red glow so one more time with the water. Smoke is thinning out, glow seems to be outside the house?? I move forward and things clear up! I am looking at a police car on the lawn with flashing lights 

Nobody was shooting at me either. 
Couch was destroyed by fire as were curtains and molding. Wall phone on the other side of the room was melted. Scorch marks (light charing) about 3-4 feet down from the ceiling all around the room.

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## Greg Boeser (May 28, 2018)

DarrenW said:


> So at best Yoshino may have had 4-5 "actual" kills, right? That's if we use a calculation oft performed on this forum, when discussing allied victory credits....


Who knows? Who cares? Different air forces used different criteria for awarding kills. Some awarded full credit for shared kills, others did not. In the end what mattered was which side could sustain the attritional nature of protracted air operations. The Tainan probably lost more aircraft on the ground to bombing and strafing and to operational accidents than in actual air combat. This is probably true for all air forces. Parsifal pointed that out earlier when he highlighted the disastrous losses suffered by the 8th FG just trying to get their planes from Townsville to Port Moresby. They were not unique.

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## parsifal (May 28, 2018)

Absolutely. In the end, the Japanese report in their own tallies the loss of more than 6500 a/c to the end of 1943. Major cause from that wasnt due to air combat with enemy (Allied ) fighters. they lost something like 40% of a/c on the ground and a large percentage that simply failed to return, often when allied aircraft were nowhere near them. Navigational errors are thought to be the most prevalent cause for these unexplained losses.

The application of airpower is subtle and yet brutal at the same time. Losses to direct combat are not the major determinant of losses, or even the major cause or measure for victory. The losses arose from a whole host of other associated activities....being bombed, getting lost, simply wear and tear. The measure of success isn't that you shoot down 50 or 100 a/c, but that you are able to do the things you want to do with your air assets, whilst preventing, or making excessively costly for the opponent to do the same. its called force projection.

8FG took one hell of a beating May-September. they lost more than they shot down. that is absolutely not the way to measure their success.. They extracted a cost from the Japanese that was sufficient, and prevented their (the Japanese) air assets from materially affecting the battle on the ground and at sea. In the end that was what mattered. .

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## DarrenW (May 28, 2018)

So Yoshino's victory tally is much lower than he boasted, some due to blatant overclaiming. Got it.

And I don't need an "official record" in order to critically analyze the personal accounts and memoirs of axis fighter pilots and their leaders. The veracity of their claims shouldn't be ignored just because they happened to be unfortunate enough to lose the war.

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## DarrenW (May 28, 2018)

Greg Boeser said:


> Who knows? Who cares?



If Yoshino's aerial victories don't really matter to you, why bring them up then?


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## Glider (May 28, 2018)

parsifal said:


> Absolutely. In the end, the Japanese report in their own tallies the loss of more than 6500 a/c to the end of 1943. Major cause from that wasnt due to air combat with enemy (Allied ) fighters. they lost something like 40% of a/c on the ground and a large percentage that simply failed to return, often when allied aircraft were nowhere near them. Navigational errors are thought to be the most prevalent cause for these unexplained losses.
> 
> The application of airpower is subtle and yet brutal at the same time. Losses to direct combat are not the major determinant of losses, or even the major cause or measure for victory. The losses arose from a whole host of other associated activities....being bombed, getting lost, simply wear and tear. The measure of success isn't that you shoot down 50 or 100 a/c, but that you are able to do the things you want to do with your air assets, whilst preventing, or making excessively costly for the opponent to do the same. its called force projection.
> 
> 8FG took one hell of a beating May-September. they lost more than they shot down. that is absolutely not the way to measure their success.. They extracted a cost from the Japanese that was sufficient, and prevented their (the Japanese) air assets from materially affecting the battle on the ground and at sea. In the end that was what mattered. .


Totally agree and its often overlooked as people get hung up with numbers. If you have the resources to handle the losses and can impose your will onto the battlefield then you win and the other guy loses

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## parsifal (May 28, 2018)

Yoshino was credited with 15 victories as I understand it . That number is based on admitted losses from Allied sources rather than the over-inflated claims made by the Japanese flyers themselves. 

What makes you believe he only shot down 4.5 allied a/c?


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## GrauGeist (May 29, 2018)

Overclaiming is not solely pinned on Axis nations, despite some observations, but happened across the board.

As has been stated (exhaustively) already, the heat of battle can lead to incorrect claims, mis-identification can lead to claims and then there is also the political aspect of it - both for the public's consumption and to bolster moral.

One of the reasons why the "losers" numbers seem to be erratic, is because towards the end of the war, record keeping was in complete chaos.


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## gomwolf (May 29, 2018)

Hmmmm...... It is quite weird, but IMHO, Nikolay Gerasimovich and interviewer doesn't understand difference between IAS and TAS...

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## XBe02Drvr (May 29, 2018)

Glider said:


> If you have the resources to handle the losses and can impose your will onto the battlefield then you win and the other guy loses


Isn't this what Isoroku Yamamoto tried to tell the Imperial Council when they asked him for a war plan to defeat America? He had been many years in the US and seen its resources first hand.
Cheers,
Wes


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## XBe02Drvr (May 29, 2018)

gomwolf said:


> Hmmmm...... It is quite weird, but IMHO, Nikolay Gerasimovich and interviewer doesn't understand difference between IAS and TAS...


Well at least the interviewer doesn't, and something got lost in the translation. And if you're driving a weird foreign airplane with weird markings on the gages, do you even give a flying fig for TAS? Your world is governed by IAS, the observed relative speeds of your opponents, the colored limitations bands your comrades in Technical Services have painted on your ASI, and the needle on your fuel gauge. The numbers are for engineers to consider who are not getting shot at.
Cheers,
Wes

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## gomwolf (May 29, 2018)

XBe02Drvr said:


> Well at least the interviewer doesn't, and something got lost in the translation. And if you're driving a weird foreign airplane with weird markings on the gages, do you even give a flying fig for TAS? Your world is governed by IAS, the observed relative speeds of your opponents, the colored limitations bands your comrades in Technical Services have painted on your ASI, and the needle on your fuel gauge. The numbers are for engineers to consider who are not getting shot at.
> Cheers,
> Wes



Normally, aircraft specifications were recorded with TAS(at least germans did) and only figure you can only see is IAS when you are in the cockpit. In addition, Nikolay Gerasimovich said technicians took away their speed figure differently by altitude. So, if they didn't educated about the difference of both, It is quite possible that they didn't understand about it.

I don't know about ww2 soviet pilot training process, so if someone who know about it, plz add some more information.

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## parsifal (May 29, 2018)

Soviet new pilots' flying time, was nowhere near that of other countries. Soviet top fighter ace in World War II - Ivan Kozhedub - once said in an interview that he'd received 100 hours of flight training at his aviation school. Another pilot - Evgeny N. Stepanov said he'd got 80. But both finished training _before_ the German invasion in June 1941. In the dark days of 1941 and 42, well, Soviet pilots often got only 8-10 hours of flight training before combat. Bergstrom in his book on Kursk said that by 1943, VVS pilots were receiving somewhere between 20-40 flying training. By 1944, the situation had improved. Ive read that by mid'44, VVS pilots were receiving about 150 hours flying training. The number tended to go up in later years.

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## GrauGeist (May 29, 2018)

The contrast between the VVS pilot's training and the Luftwaffe's Fleigerschule training at the onset of the war was night and day.
The Soviets were at a clear disadvantage both in pilot skill and equipment until the tipping point about mid-war, when the Soviet pilots were able to have better equipment and training and the Luftwaffe was suffering from attrition in regards to replacement pilot quality and equipment supply short-comings.

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## gomwolf (May 29, 2018)

Actually, the meaning of soviet pilot training I said was hummm... "Were they learned basic aerodynamics like differences between IAS and TAS?"


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## XBe02Drvr (May 29, 2018)

gomwolf said:


> Actually, the meaning of soviet pilot training I said was hummm... "Were they learned basic aerodynamics like differences between IAS and TAS?"


How many people have YOU, personally, taught to fly?? I did it professionally for years, and I'm here to tell you that if you're going to train pilots to do just a few things, and you don't have much time and resources to do it with, you don't need to "waste" time on the niceties of TAS vs IAS. These guys (and gals) aren't going to fly at high altitudes, or at night, or on the gages. At least not until they've survived the front long enough to gain a little experience.
For flying that's going to stay below oxygen altitudes, the difference between True and Indicated isn't going to be all that great, and is something the Technical Services people can compensate for by making sure all placards and instrument markings corelate to IAS.
I've soloed students with less than five hours of flight time. That doesn't mean they were ready to fly to and land at JFK. That means that on a nice sunny day, with the wind right down the runway, and not much traffic, they could get the plane safely into the air, around the pattern, and back on the ground in an acceptable manner, with me watching intently, radio in hand, ready to give advice if asked. The rest of pilot training is learning to deal with all the less-than-optimum situations that are sure to arise. The idea that, as Parsifal suggests, they might be expected to fly into combat in a high performance airplane with only another three to five hours of instruction is a chilling thought. No wonder the Experten ran up such scores!
It took me five hours to get signed off in the T-34 (a 230 HP retractable gear military trainer), and I already had ninety five hours flying time, including a thousand mile cross-country. At that point, I was nowhere near ready to even get near a 1200 HP fighter plane, say nothing of going out to play tag with Erich Hartman in it.
Cheers,
Wes

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## gomwolf (May 29, 2018)

I couldn't understand why you so angry. I apologize if I said something rude. I am often misunderstood because I am not a native English speaker. However I served in the Army and I'm in reserve army now, but I don't care if someone who have no military experience talks about Army. I just telling about that Russian pilot and interviewer seems doesn't understand about differences between IAS and TAS and that seems the reason they couldn't reach the speed recorded at specification.

Gomwolf.

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## XBe02Drvr (May 29, 2018)

gomwolf said:


> I couldn't understand why you so angry. I apologize if I said something rude.


Sorry, brother, I wasn't mad, and I apologise if I sounded that way to you. It's just that for some kinds of flying and some circumstances, the differences between IAS and TAS just aren't that big a deal, and if the Russian pilot involved was an experienced aviator he probably did understand the difference, but maybe didn't express it very clearly, or the interviewer didn't understand the explanation and the meaning got lost in the translation.
BTW, thank you for your service. And keep plugging away at your English, it's a damn hard language to learn, but it gets easier as the years go by.
Cheers,
Wes


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## gomwolf (May 29, 2018)

I understand what you said. It seems quite reasonable.

This words are just for prevent another misunderstanding. I served in the Army but I am not US citizen. However, my country is one of strong ally of United States.

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## swampyankee (May 29, 2018)

IAS is how the plane flies; TAS is how it covers ground. And airplane that stalls at 75 knots IAS does so at sea level or 20,000 ft; at sea level TAS=IAS, but the TAS at 20,000 is considerably different from the indicated airspeed. Since landing, takeoff, and maneuver speed (at a given weight and flap setting) are constant in terms of IAS, specifying those in terms of TAS seems odd.

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## XBe02Drvr (May 29, 2018)

swampyankee said:


> Since landing, takeoff, and maneuver speed (at a given weight and flap setting) are constant in terms of IAS, specifying those in terms of TAS seems odd.


Ah, but it makes for a more impressive number, especially at altitude!
Cheers,
Wes


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## Shortround6 (May 29, 2018)

let me see if I have this straight, It appears you "fly" the plane using IAS but you navigate (find next airport?) using TAS?


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## Glider (May 29, 2018)

All I can say is that if an instructor told me to go solo after 5 hours, I would stay firmly on the ground and ask for a different instructor. 
No one, no matter how gifted, or how benign the conditions, has the skill and knowledge to handle the eventualities that can happen in flight in five hours.


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## DarrenW (May 29, 2018)

parsifal said:


> Yoshino was credited with 15 victories as I understand it . That number is based on admitted losses from Allied sources rather than the over-inflated claims made by the Japanese flyers themselves.
> 
> What makes you believe he only shot down 4.5 allied a/c?



Do you happen to have some sort of list, specifying the actual aircraft destroyed by Yoshino, according to allied sources? And I wonder how many Japanese pilots were given credit for the same allied aircraft, as these "lists" were developed years later by various authors and historians through their own individual research. There is no central data base which is monitored by an impartial person, in order to compare them and weed out the identical claims and losses. That's just one of the reasons I have a hard time trusting the aerial victory totals of the axis nations that I often read about in books and on the web, but for some reason they are much less scrutinized here and elsewhere. If you can easy discount official US Navy documents and trust wholeheartedly in the Japanese version of events, then I think it's not too extreme of me to question the validity of victory totals created decades after the war by people who might just have an axe to grind. 

And the 4-5 victory tally for Yoshino was calculated by using your formula to derive the actual number of aircraft destroyed in aerial combat. I believe you mentioned that only about a third of credited aerial victories resulted in the destruction of an enemy aircraft. If it works for the allies it should also work for the Japanese as well....


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## P-39 Expert (May 29, 2018)

Shortround6 said:


> Some of it was blatant overclaiming and some was honest mistakes in the heat of battle. Fired at plane, saw smoke and figured it was damaged/on fire.
> Things can get confusing real quick.
> Firefighter story, One of the first times I went in as a nozzle man we entered through the kitchen to attack a couch fire in the living room (Push fire out the front window to save the rest of the house.) Lots of heat and smoke, can't see much more than a dim glow through the smoke. I point the nozzle and open it up and give it a couple of swirls and shut down to see effect. The glow is much smaller so I repeat. Still getting a pulsating red glow through the smoke and steam so I try it again. Still getting that pulsating red glow so one more time with the water. Smoke is thinning out, glow seems to be outside the house?? I move forward and things clear up! I am looking at a police car on the lawn with flashing lights
> 
> ...


Great story. But more importantly, did you claim the couch as a victory?

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## DarrenW (May 29, 2018)

parsifal said:


> A few of the more well known Aces of the 80th Fighter Squadron were Major Jay T. Robbins (22 confirmed kills) and Major Richard I. Bong (40 confirmed kills). Between them, based on these ‘”confirmed” kills, they had managed to destroy the entire tainan AG severasl times over!!!!!!!!



Neither Robbins nor Bong made claims against the Tainan Air Group; it was disbanded months before their first aerial victories were made. And from what I can tell Bong never served in the 80th Fighter Squadron. Can you clarify?


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## FLYBOYJ (May 29, 2018)

DarrenW said:


> Neither Robbins nor Bong made claims against the Tainan Air Group; it was disbanded months before their first aerial victories were made. And from what I can tell Bong never served in the 80th Fighter Squadron. Can you clarify?


According to the 80th FS history page he did.
http://80fsheadhunters.org/wp-content/uploads/2013/05/Headhunter-Headlines-1-Apr-92.pdf

Records show in Feb., 1944 Bong was assigned to the V Fighter Command HQ, so he was allowed to attach himself to any unit.


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## swampyankee (May 29, 2018)

Shortround6 said:


> let me see if I have this straight, It appears you "fly" the plane using IAS but you navigate (find next airport?) using TAS?


Yes. IAS is measured by measuring a pressure and “calculating” speed by assuming sea level density. At sea level, std day TAS and IAS are equal; 100 knots true air speed gives about 33.8 psf pressure. At 20,000 ft, to get the same dynamic pressure, the true airspeed is 136.5 kts.


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## GrauGeist (May 29, 2018)

DarrenW said:


> Neither Robbins nor Bong made claims against the *Tainan Air Group; it was disbanded months before their first aerial victories were made*. And from what I can tell Bong never served in the 80th Fighter Squadron. Can you clarify?


The Tinian Air Group was formed in October 1941 (originally attached to the 25th Air Flotilla) and was restructured in November 1942, with several more changes, the Tinian Air Group continued operations until the Island was attacked and captured by Allied forces in July of 1944.
Olds and Bong had scored quite a few victories prior to June of 1944...


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## YF12A (May 29, 2018)

The B-29's sure found out how big a difference there could be between IAS and TAS when they first started flying high altitude missions over Japan and encountered the jet stream effect.

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## Juha2 (May 29, 2018)

GrauGeist said:


> The Tinian Air Group was formed in October 1941 (originally attached to the 25th Air Flotilla) and was restructured in November 1942, with several more changes, the Tinian Air Group continued operations until the Island was attacked and captured by Allied forces in July of 1944.
> Olds and Bong had scored quite a few victories prior to June of 1944...



Darren was talking on the Tainan AG not Tinian. Tainan AG returned to mainland Japan in Nov. 1942 as a AG 251. AG 251 returned to Rabaul in May 1943

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## Greg Boeser (May 29, 2018)

DarrenW said:


> If Yoshino's aerial victories don't really matter to you, why bring them up then?


Because victory tallies played a role in building and retaining morale, both in the fighting units and back home. It is a measure of the pilot's stature. A quantitative measure of qualitative skill. A pilot's claims were his measure of success. Vetting the records and discovering that a majority of claims were unsubstantiated does not take away from the esteem these pilots had at the time. Most claims were made in good faith, I would not use the term "blatant", because that implies the pilot was knowingly making a false claim.


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## Juha2 (May 29, 2018)

FLYBOYJ said:


> According to the 80th FS history page he did.
> http://80fsheadhunters.org/wp-content/uploads/2013/05/Headhunter-Headlines-1-Apr-92.pdf
> 
> Records show in Feb., 1944 Bong was assigned to the V Fighter Command HQ, so he was allowed to attach himself to any unit.



But up to that time all his claims were while serving with 9th FS, first claims on 27 Dec 42, by which time the Tainan AG was already history.

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## DarrenW (May 29, 2018)

FLYBOYJ said:


> Records show in Feb., 1944 Bong was assigned to the V Fighter Command HQ, so he was allowed to attach himself to any unit.



Ah, so there's the connection between Bong and the 80th. He was never officially assigned to the squadron so it's often not mentioned. Thanks for the clarification.

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## XBe02Drvr (May 29, 2018)

Glider said:


> No one, no matter how gifted, or how benign the conditions, has the skill and knowledge to handle the eventualities that can happen in flight in five hours.


Understand, "going solo" in the context of primary flight instruction does not imply authority to go hop in the plane at will and blast off into the wild blue. The first 3 - 5 solo flights are supervised solos that start off as dual instruction and then have a solo session incorporated under the strict observation and supervision of the instructor. Five hour solos were not routine or common, but an exceptionally adept student could achieve it if they could absorb all the requisite skills in that amount of time. And if you're operating from a low traffic rural airport with enough different runways to handle a variety of wind conditions the occasional talented student could do it, if old man weather cooperated. YOU wouldn't have soloed in five hours, even if the skill set was in place, because you wouldn't have been mentally ready and I wouldn't have made that call. I've had students that were "ready" skillwise to solo in seven or eight hours, but didn't have the confidence to be mentally ready until they were up to twelve or more. These were often of the perfectionist persuasion, and made some of the best pilots in the end.
The FARs delineate what a student must be trained before they can solo, and I always threw in a few "extra" emergency procedures. They best be on their toes, as every .7 or .8 hour lesson would have at least one emergency of some kind.
Before takeoff checklist complete, pattern clear, position and hold, think, "This is the time the engine will quit 200 feet over the departure end; what am I going to do?", before every takeoff.
"Oswego traffic, Cessna seven five seven Bravo Yankee, left crosswind one six, departing east to the practice area." Now if the engine quits right here, where am I going to park this bird?
Bear in mind, my instructing days were in the 70s and 80s, when tort law was not so all-pervasive as it is today. Today I would probably be a little more restrained with the talented super student. Even then, none of mine soloed without first demonstrating a spin recovery, which was above and beyond the FARs.
Cheers,
Wes


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## DarrenW (May 29, 2018)

Greg Boeser said:


> Because victory tallies played a role in building and retaining morale, both in the fighting units and back home. It is a measure of the pilot's stature. A quantitative measure of qualitative skill. A pilot's claims were his measure of success. Vetting the records and discovering that a majority of claims were unsubstantiated does not take away from the esteem these pilots had at the time. Most claims were made in good faith, I would not use the term "blatant", because that implies the pilot was knowingly making a false claim.



All of that is very true. But now that we know that there are obvious discrepancies in his record, maybe we should accept the possibility that Yoshino really wasn't as good as first thought. Maybe that's why he was eventually waxed while performing such a stupid maneuver???


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## FLYBOYJ (May 29, 2018)

Juha2 said:


> But up to that time all his claims were while serving with 9th FS, first claims on 27 Dec 42, by which time the Tainan AG was already history.


All true and agree, my point was Bong flew with the 80th (as well as many other units) after his appointment to V Fighter Command HQ. I have no dog in the fight with regards to the comments about the Tainan AG


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## XBe02Drvr (May 29, 2018)

DarrenW said:


> Maybe that's why he was eventually waxed while performing such a stupid maneuver???


What do you mean "stupid maneuver"? He was kind of boxed in, harrying the B-26s at low altitude his options were limited. The B-26 was a speed demon bomber, so if he had overtake speed on them, he was up in the speed range where the Zero was pretty stiff in roll, so he wasn't going to win a turning fight if he lived to get into it, but he had speed, so up was the viable option. This is a situation where control harmony at speed is the deciding factor. Heavy high speed stick forces in the Zero, vs light and responsive in the ("twitchy" aft engine) P-39 allowed the Cobra to stay with him in the pull-up. His goose was pretty much cooked from the onset. His only other survival option might have been a (muscular!) roll to the left into the tightest turn he could manage at that speed and hope the American misjudges his deflection as he gets in a quick snap shot before popping up into his zoom climb. This might have achieved survival, but no victory, an unattractive prospect for any self-respecting Samurai. The zoom into a loop onto the opponent's tail is much more attractive. He just didn't expect the clunky, slow climbing Cobra to commit suicide by trying to go vertical with him.
Cheers,
Wes


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## DarrenW (May 29, 2018)

He could have quickly throttled back and rolled out, then immediately revert to defensive turning. This would have forced the American to turn too, in order to keep him in his sights. This would have put the American at a disadvantage if he continued turning with the more maneuverable Zeke. Instead, Yoshino misjudged his opponent's abilities and over-reacted to the threat. Two major flaws that manifest themselves in fighter pilots who have trouble thinking under pressure. The hype that surrounds Yoshino is unwarranted IMHO.


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## Glider (May 29, 2018)

XBe02Drvr said:


> Understand, "going solo" in the context of primary flight instruction does not imply authority to go hop in the plane at will and blast off into the wild blue. The first 3 - 5 solo flights are supervised solos that start off as dual instruction and then have a solo session incorporated under the strict observation and supervision of the instructor. Five hour solos were not routine or common, but an exceptionally adept student could achieve it if they could absorb all the requisite skills in that amount of time. And if you're operating from a low traffic rural airport with enough different runways to handle a variety of wind conditions the occasional talented student could do it, if old man weather cooperated. YOU wouldn't have soloed in five hours, even if the skill set was in place, because you wouldn't have been mentally ready and I wouldn't have made that call. I've had students that were "ready" skillwise to solo in seven or eight hours, but didn't have the confidence to be mentally ready until they were up to twelve or more. These were often of the perfectionist persuasion, and made some of the best pilots in the end.
> The FARs delineate what a student must be trained before they can solo, and I always threw in a few "extra" emergency procedures. They best be on their toes, as every .7 or .8 hour lesson would have at least one emergency of some kind.
> Before takeoff checklist complete, pattern clear, position and hold, think, "This is the time the engine will quit 200 feet over the departure end; what am I going to do?", before every takeoff.
> "Oswego traffic, Cessna seven five seven Bravo Yankee, left crosswind one six, departing east to the practice area." Now if the engine quits right here, where am I going to park this bird?
> ...


My experience was in gliders with twenty years experience on and off with about eight as an instructor in the 70's and 80's. We will simply have to agree to disagree as there are a number of fundamental differences, namely:-

The gliders we used didn't have radios and I wouldn't have used one if they had, as that would be a distraction. I would want the student to be totally focused on the task in hand and not listening to a radio if things start to go wrong. If there going to go wrong it's probably on the circuit and approach where using a radio would be useless as seconds count.
You have to have total confidence in a student as there are no second chances on landing, if the student messes it up, they have to sort it out on their own, going around isn't an option.
The rules are very strict about what a student has to do before going solo including a number of spins including initiating a full spin starting at 2000ft and obviously recovering from it​
Cable breaks were not unknown and these had to be done from a variety of heights 
Cross wind landings had to be taught as the wind can change at any time 
High speed stalls not just normal stalls had to be covered
How to handle a slow, variable or fast cable launch
and so on
A good student would take about eighty flights to go solo, an exceptional one less but all would be more than five hours

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## parsifal (May 29, 2018)

_Do you happen to have some sort of list, specifying the actual aircraft destroyed by Yoshino, according to allied sources?_

No

_And I wonder how many Japanese pilots were given credit for the same allied aircraft, as these "lists" were developed years later by various authors and historians through their own individual research. _

Possible but less likely than an allied bias, since much of the starting material has an inherent allied bias, due to the source material. Many histories are based on the allied claims based data drawn up after the war, whereas the Japanese losses, where it is available, is based on their own wartime campaign records. Unfortunately those campaign records are incomplete. Many were lost in the subsequent fire bombing campaigns against the homeland, other (aircraft) were lost to unknown causes (like the allies I might add). In those situations we do have to rely on a degree of claims data……pilot x claims he shot down an enemy a/c in a certain area at a certain time. Pilot Y from the other side is recorded as missing in that area at a certain time, that matches the claim. In that circumstance it is reasonable to credit the claim. 

_There is no central data base which is monitored by an impartial person, in order to compare them and weed out the identical claims and losses. That's just one of the reasons I have a hard time trusting the aerial victory totals of the axis nations that I often read about in books and on the web, but for some reason they are much less scrutinized here and elsewhere. _

Your right, they are placed under a lesser level of scrutiny. Its because of the source of the starting points. As Ive alluded to several times, our overall view of losses are based on allied claims data, at least in the PTO. There is no equivalent that is so complete, and so accepted universally from the axis perspective. Doesn’t mean that the axis aren’t vulnerable to creative accounting in the same way as the allies. Lord knows that happens with annoying regularity, particualalry for the LW Ra Ra boys. I get it.

With an inherent pro-Allied bias in the starting data, it’s a natural tendency to try and compensate for that . 

_If you can easy discount official US Navy documents and trust wholeheartedly in the Japanese version of events, then I think it's not too extreme of me to question the validity of victory totals created decades after the war by people who might just have an axe to grind._

Im not a good enough student of the subject to be able to fully respond to this. Maybe you have a point. However when the claims data are known to exceed the total forces committed on the other side, you just know that something is wrong. It might be distasteful, but the basic situation is what it is. We then have to find ways of rationalizing what we are confronted with.

I would recommend that you find an event and tally the US claims data for that data with the known primary Japanese sources for their losses. Someone like Shinpachi, if you ask him politely can be a huge help in this type of exercise. Tally your Allied sources, to the Japanese sources, and immediately and almost universally the overclaiming problem will be revealed. This happens again and again. Its just as bad when the Japanese unadulterated claims are held up to the light, but most published Japanese victories in the English language aren’t based on their claims, its based on the post war known allied losses

_And the 4-5 victory tally for Yoshino was calculated by using your formula to derive the actual number of aircraft destroyed in aerial combat. I believe you mentioned that only about a third of credited aerial victories resulted in the destruction of an enemy aircraft. If it works for the allies it should also work for the Japanese as well...._

Japanese claims data is worse than the 3:1 error rate, but Japanese claims data is not relevant. As a generalisation Japanese claims are not used to tally up their post war victory estimates. Allied known losses are the primary data sources. Where those known losses match Japanese claims data, it gets down to which Japanese flyer in that combat has the most reliable claim.

So it doesn’t work both ways Im afraid. Allied losses have an inherent starting bias, because many of the accounts are based solely on the (allied) claims based datasets, whereas the Japanese are not. It is far from infallible, but the inherent pr-allied bias is clearly there.


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## XBe02Drvr (May 29, 2018)

Glider said:


> A good student would take about eighty flights to go solo, an exceptional one less but all would be more than five hour


I also instructed in Schweitzer 2-33s and a 2-32, Lark IS-28Bs, Grob 103, and ASK-21. Glider training is a different animal altogether. We had a particularly difficult mountain airfield to fly from, so student proficiency had to be top-notch, but the lift was fabulous, including mountain wave that could sometimes be accessed right over the field with a 3000 ft tow. No winch launches here! In fact winch launches seem to be pretty rare in the US.
A14 year old club worker/student and I once thermalled a 2-33 into the bottom of the wave and pegged the variometer, kinda leaving the world behind and went up like a rocket. Before I knew it, we were shooting through 11,000 ft MSL, and I was getting concerned, as we had no oxygen, were wearing shorts and tee shirts, and had no radio to call ATC and ask them to open the wave window (our field was under a Victor airway). Spoilers out, diving at max maneuvering speed, we were still going up, and I couldn't seem to get us out of the lift zone. Finally, at 17,600 MSL we flew out of the lift and pegged the variometer down, by which time we were both pretty blue, and didn't see or hear the FB-111 coming until he shot by a couple hundred feet away. He was startled too, and came back around for another looksee, this time in slow?flight with everything hanging, but still two or three times our speed, with the B/N snapping pictures of us.
With the aerotows and longer flights we didn't need anywhere near so many flights to solo a student, but with the deceptive approaches to the field and the challenging terrain, we had to do a series of pattern tows and rope breaks with a student nearing solo. But once they could land reliably at the 'bush they were safe anywhere.
Cheers,
Wes

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## XBe02Drvr (May 30, 2018)

DarrenW said:


> He could have quickly throttled back and rolled out, then immediately revert to defensive turning. This would have forced the American to turn too, in order to keep him in his sights. This would have put the American at a disadvantage if he continued turning with the more maneuverable Zeke.


Throttle back and slow down into the Zero's optimum speed range only works if you have time enough to accomplish it before your attacker is in firing range. Like any aggressive fighter pilot, Yoshino quite likely would have been focusing on his prey with an occasional glance over his shoulder to check six. Head on silhouette of a P-39 is pretty slim, and on a collision course would be a stationary image, easy to miss in the heat of battle. Many an accomplished fighter pilot has died this way.
If he did manage the "slow down, roll, and pull it tight" successfully, it would all depend on suckering the American into slowing down and joining the circle, something a savvy Cobra pilot should avoid like the plague.
The Cobra is sleek and heavy for its size, hence a good diver and zoomer, but not given to slowing down quickly. With the speed from his dive, the P-39 pilot would be certain to get sucked in his turn and keeping the Zero in his sights not an option. So the options are: dive (oops, we're already just above the wavetops) or zoom climb (something the Airacobra does well) giving both altitude and speed advantage over the opponent. In ACM energy is life. If Yoshino bugs out (not likely for an adrenalated Samurai), you have the speed and altitude to run him down, and if he tries to match your zoom from his slowed down high-G turn, you're going to be on top and can make a diving head on pass into his climb. His cannons have lousy ballistics uphill and you're a slender target, while your diversified battery of MGs and cannon are shooting downhill into a radial engine target.
Cheers,
Wes


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## DerAdlerIstGelandet (May 30, 2018)

Glider said:


> My experience was in gliders with twenty years experience on and off with about eight as an instructor in the 70's and 80's. We will simply have to agree to disagree as there are a number of fundamental differences, namely:-
> 
> The gliders we used didn't have radios and I wouldn't have used one if they had, as that would be a distraction. I would want the student to be totally focused on the task in hand and not listening to a radio if things start to go wrong. If there going to go wrong it's probably on the circuit and approach where using a radio would be useless as seconds count.
> You have to have total confidence in a student as there are no second chances on landing, if the student messes it up, they have to sort it out on their own, going around isn't an option.
> ...



80 flights to solo? Wow!

I have never flown a glider, but I do have a private pilots license, and I did my first solo at 14 flights (which I think was a little slow). It was a controlled solo. I first went up with my instructor and reviewed some things (I had an idea I would be soloing, as he told me to bring a white shirt), and then we landed. He got out, and told me to give him 3 takeoffs and landings to a complete stop. 

Obviously I had radios too. First I was in a powered single engine aircraft, and two I was flying out of an active airport. At the same time, my instructor was sitting in an airport vehicle near the runway, watching me the whole time. He had a handheld radio to talk to me if I had issues or problems. He also had my wife in the truck with him, so that she could watch me solo for the first time. 

Amazing experience, and probably the only thing more amazing in time as a pilot so far, was my check ride.

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## Glider (May 30, 2018)

We were limited to winch launches which get you to about 1,800 - 2,000 ft so you had to find lift within 4-5 minutes or you came straight down. So a lot of those launches will be 10 minute flights. Good for take off and landing practice but you need longer flights to teach a lot of the skills needed. Also as mentioned earlier we had to cover a lot of things before anyone is allowed to go solo.
Don't knock cable launches though, they are very exhilarating things to do. 0 - 60 mph in 2.5 seconds and 30 seconds from a standing start to 2,000 ft, balancing the whole thing on one wheel and dealing with crosswinds, does tend to keep you on your toes. You don't have time to think about a problem you just have to react.

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## XBe02Drvr (May 30, 2018)

Glider said:


> We were limited to winch launches which get you to about 1,800 - 2,000 ft so you had to find lift within 4-5 minutes or you came straight down. So a lot of those launches will be 10 minute flights. Good for take off and landing practice but you need longer flights to teach a lot of the skills needed. Also as mentioned earlier we had to cover a lot of things before anyone is allowed to go solo.
> Don't knock cable launches though, they are very exhilarating things to do. 0 - 60 mph in 2.5 seconds and 30 seconds from a standing start to 2,000 ft, balancing the whole thing on one wheel and dealing with crosswinds, does tend to keep you on your toes. You don't have time to think about a problem you just have to react.


I rode through three winch launches in an ancient Schweizer TG-2 with a CG hook when I was a 14 yr old CAP cadet. Closest thing to a catshot you can get on dry land! The clmbout was spectacular, and with the zero downward visibility from the back seat all you could see was sky. Felt like vertical!
Unfortunately the launching/landing area was only 4500 ft long, and the glider was a pre-WWII style "floater" design with low limit speeds, so 1100 ft was about max if you did everything just right. Fortunately there were pastures and plowed fields right next door with reliable thermals.
The guy who owned the winch and glider was an ex Netherlands AF Hunter pilot, and a bit of a hotrodder to boot, and he had a monster Pontiac V-8 in the winch that he had dynoed at 400 HP before he swapped it from his drag car to the winch.
Such fun!!
Cheers,
Wes
PS: One day a guy showed up trailering a Schweizer 2-32 (the B-52 of gliders) and wanted to get checked out on winch launches. Now the 2-32 is a heavy SOB, can carry three people, and is built like the Brooklyn Bridge. With its clean design, huge wings and high limit speeds and G limits, it could get easily 1300-1400 ft with that hotrod winch.
Years later, I encountered that same 2-32 in the hands of the local glider club, and gave many enjoyable rides in it, as well as the occasional lesson. It was a lousy thermaller with its weight and speed, but a dynamite ridge runner and wave flyer.


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## XBe02Drvr (May 31, 2018)

DerAdlerIstGelandet said:


> Amazing experience, and probably the only thing more amazing in time as a pilot so far, was my check ride.


What did you learn on your checkride? My Private Pilot Examiner said "Sweat thyself not, this is just another lesson. We're going to educate each other: you're going to show me how safe a pilot you are, and I'm going to show you a thing or two your instructors never did. So after he put me through my paces, he said "You'll do", then asked: "Have you ever been in a fully developed spin in one of these things?"
"No, we did spin avoidance but no spins".
"Yep, that's what your logbook shows, would you like to see what it's like?"
"Isn't that considered acrobatics?"
"Yep, and it's prohibited except when operating in Utility Category and in a training situation. You're Pilot in Command of this flight, I'm legally just a passenger, so I'm asking, do we meet the stated conditions to do it legally?"
"I guess so."
"Okay, you want to give it a try? Remember, you're PIC."
So he demonstrated, I followed through, then did one each way myself, and got thoroughly hooked on "the world turned upside down"!
Cheers,
Wes

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## DerAdlerIstGelandet (May 31, 2018)

XBe02Drvr said:


> What did you learn on your checkride? My Private Pilot Examiner said "Sweat thyself not, this is just another lesson. We're going to educate each other: you're going to show me how safe a pilot you are, and I'm going to show you a thing or two your instructors never did. So after he put me through my paces, he said "You'll do", then asked: "Have you ever been in a fully developed spin in one of these things?"
> "No, we did spin avoidance but no spins".
> "Yep, that's what your logbook shows, would you like to see what it's like?"
> "Isn't that considered acrobatics?"
> ...



My examiner said the same thing to me. He said that besides verifying that I am a safe pilot, he also wanted to teach me something. That my checkride was not complete unless it was an important lesson.

His father had been killed in a spin, and he wanted to hone in on spin training, but the aircraft was restricted from spins at any time. But he did as much as he could to hone in on the importance of spin avoidance, and recovery from one. He went into more detail than the books or my instructor did during training. It was a great experience. I was on cloud nine afterwards.

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## XBe02Drvr (May 31, 2018)

DerAdlerIstGelandet said:


> His father had been killed in a spin, and he wanted to hone in on spin training,


A windshield full of trees going round and round is a lot less paralyzing if you've been there before. A trainer that's not spin able is a travesty. If it's capable of getting into a spin, but its spin characteristics are unsafe, then it's unairworthy and shouldn't be used as a trainer.
I never was comfortable with the FAA's promotion of "gentle" flight instruction. (Don't do anything that might make the student nervous or uncomfortable! And don't let them get the idea that there could be any fear involved.) That creates "armchair pilots" liable to freeze on the controls when that assymetric stall happens turning downwind to base because they were holding the nose too high and "ruddering" the plane around in their nervousness about lowering the nose and using the appropriate bank angle less than 1000 ft AGL.
Look at the accident statistics back in the day.
Cheers,
Wes

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## jmcalli2 (May 31, 2018)

XBe02Drvr said:


> What do you mean "stupid maneuver"? He was kind of boxed in, harrying the B-26s at low altitude his options were limited. The B-26 was a speed demon bomber, so if he had overtake speed on them, he was up in the speed range where the Zero was pretty stiff in roll, so he wasn't going to win a turning fight if he lived to get into it, but he had speed, so up was the viable option. This is a situation where control harmony at speed is the deciding factor. Heavy high speed stick forces in the Zero, vs light and responsive in the ("twitchy" aft engine) P-39 allowed the Cobra to stay with him in the pull-up. His goose was pretty much cooked from the onset. His only other survival option might have been a (muscular!) roll to the left into the tightest turn he could manage at that speed and hope the American misjudges his deflection as he gets in a quick snap shot before popping up into his zoom climb. This might have achieved survival, but no victory, an unattractive prospect for any self-respecting Samurai. The zoom into a loop onto the opponent's tail is much more attractive. He just didn't expect the clunky, slow climbing Cobra to commit suicide by trying to go vertical with him.
> Cheers,
> Wes



Just a "butt-in' thought on the phrase, "Slow-climbing P-39". See the performance figures for the A6M2 at http://www.wwiiaircraftperformance.org/japan/a6m2-oct2342.pdf and P-39N at http://www.wwiiaircraftperformance.org/P-39/P-39N_FS-M-19-1487-A.pdf

This suggests that climbing at low/medium altitude when bounced by a P-39 is not a good idea.

Just my 2 cents.

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## XBe02Drvr (May 31, 2018)

jmcalli2 said:


> Just a "butt-in' thought on the phrase, "Slow-climbing P-39". See the performance figures for the A6M2 at http://www.wwiiaircraftperformance.org/japan/a6m2-oct2342.pdf and P-39N at http://www.wwiiaircraftperformance.org/P-39/P-39N_FS-M-19-1487-A.pdf
> 
> This suggests that climbing at low/medium altitude when bounced by a P-39 is not a good idea.
> 
> Just my 2 cents.


Poor Yoshino! He didn't have access to your sources. In fact, I believe Koga and his Zero weren't yet embarked on their carrier that day.
Cheers,
Wes


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## XBe02Drvr (May 31, 2018)

jmcalli2 said:


> Just a "butt-in' thought on the phrase, "Slow-climbing P-39". See the performance figures for the A6M2 at http://www.wwiiaircraftperformance.org/japan/a6m2-oct2342.pdf and P-39N at http://www.wwiiaircraftperformance.org/P-39/P-39N_FS-M-19-1487-A.pdf
> 
> This suggests that climbing at low/medium altitude when bounced by a P-39 is not a good idea.
> 
> Just my 2 cents.


Those figures are for a P-39N, which had 225 more HP and somewhat less weight than the D. Besides, any previous experience the Japanese had against the P-39 was most likely meeting them and bouncing them as they struggled to intercept an incoming raid with very little warning.
Cheers,
Wes

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## DerAdlerIstGelandet (May 31, 2018)

XBe02Drvr said:


> A windshield full of trees going round and round is a lot less paralyzing if you've been there before. A trainer that's not spin able is a travesty. If it's capable of getting into a spin, but its spin characteristics are unsafe, then it's unairworthy and shouldn't be used as a trainer.
> I never was comfortable with the FAA's promotion of "gentle" flight instruction. (Don't do anything that might make the student nervous or uncomfortable! And don't let them get the idea that there could be any fear involved.) That creates "armchair pilots" liable to freeze on the controls when that assymetric stall happens turning downwind to base because they were holding the nose too high and "ruddering" the plane around in their nervousness about lowering the nose and using the appropriate bank angle less than 1000 ft AGL.
> Look at the accident statistics back in the day.
> Cheers,
> Wes



I absolutely agree with you. I think spin training should be mandatory for a private pilot as well.

I remember my 1st cross country solo, I flew out to the first controlled airport, did my required touch and goes, got out and got my logbook signed by a person at the FBO. Then I took off and flew to my 2nd airport on my 2nd leg. I was so used to flying left traffic in my training, it really caught me off guard when the tower told me to fly right traffic. I asked them to repeat it, as if I had misunderstood them, but nope they said right traffic. I know I was making my base to final turn absolutely wrong, because I just was not used to it. My bank was too high, and I know my nose was too high. Stall warning came on, and it buffeted a little. I immediately lowered the nose, and was able to make a successful landing, but I can tell you my pucker factor was through the roof. My instructor had told me to do a few touch and goes there as well, before shutting down and getting my logbook signed. I had had enough for the day though after that happened, and decided to go to a complete stop, shut down, get some water, get my logbook signed, and then do a nice slow flight back home to my home airfield.


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## fubar57 (May 31, 2018)

I'm not seeing any 109s, 190s or -39s here people. JK ....I wish I had learned to fly when I had the chance

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## XBe02Drvr (May 31, 2018)

DerAdlerIstGelandet said:


> I absolutely agree with you. I think spin training should be mandatory for a private pilot as well.
> 
> I remember my 1st cross country solo, I flew out to the first controlled airport, did my required touch and goes, got out and got my logbook signed by a person at the FBO. Then I took off and flew to my 2nd airport on my 2nd leg. I was so used to flying left traffic in my training, it really caught me off guard when the tower told me to fly right traffic. I asked them to repeat it, as if I had misunderstood them, but nope they said right traffic. I know I was making my base to final turn absolutely wrong, because I just was not used to it. My bank was too high, and I know my nose was too high. Stall warning came on, and it buffeted a little. I immediately lowered the nose, and was able to make a successful landing, but I can tell you my pucker factor was through the roof. My instructor had told me to do a few touch and goes there as well, before shutting down and getting my logbook signed. I had had enough for the day though after that happened, and decided to go to a complete stop, shut down, get some water, get my logbook signed, and then do a nice slow flight back home to my home airfield.


Your instructor was brave! I never sent students out for a triangular first solo XC, always an out-and-back, and then not to a tower controlled field. That would come later, after they had ironed out their navigation and gained a little confidence. Back in the day, PP standards required a "long solo cross-country" of three 100+ NM legs, so that was usually the last one one of the series.
Cheers,
Wes


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## XBe02Drvr (May 31, 2018)

fubar57 said:


> I'm not seeing any 109s, 190s or -39s here people. JK ....I wish I had learned to fly when I had the chance


Sorry, the "digression monster" strikes again! Misjudged the crosswind component and drifted off course. Dammit, those Met guys were off again with their winds aloft!
Cheers,
Wes

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## parsifal (May 31, 2018)

fubar57 said:


> I'm not seeing any 109s, 190s or -39s here people. JK ....I wish I had learned to fly when I had the chance


Sorry Geo. My fault (to a degree)

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## DerAdlerIstGelandet (May 31, 2018)

fubar57 said:


> I'm not seeing any 109s, 190s or -39s here people. JK ....I wish I had learned to fly when I had the chance



Sorry...

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## fubar57 (May 31, 2018)

You guys could talk about blimps for all I care: for a non-flyer I find it interesting.........maybe not blimps

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## DerAdlerIstGelandet (May 31, 2018)

XBe02Drvr said:


> Your instructor was brave! I never sent students out for a triangular first solo XC, always an out-and-back, and then not to a tower controlled field. That would come later, after they had ironed out their navigation and gained a little confidence. Back in the day, PP standards required a "long cross-country" of three 100+ NM legs, so that was usually the last one one of the series.
> Cheers,
> Wes



I had to do three cross counties. 2 short, and 1 long.

I did a few out and about’s with my instructor in the plane before doing the 1st cross country. All three cross countries included 3 stops, and all had to include a controlled airport. I’ll have to look back at the requirements. I think the only the long requires 3 stops. As I said though, my instructor had me do it with all 3.


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## gumbyk (May 31, 2018)

DerAdlerIstGelandet said:


> I had to do three cross counties. 2 short, and 1 long.
> 
> I did a few out and about’s with my instructor in the plane before doing the 1st cross country. All three cross countries included 3 stops, and all had to include a controlled airport. I’ll have to look back at the requirements. I think the only the long requires 3 stops. As I said though, my instructor had me do it with all 3.


We used to do 4 cross-country flights, two to controlled airfields (one dual and one solo) and two to uncontrolled airports, again one each dual and solo.
It was the short sector flights that most students had problems with, when there are two airports less than 25nm from each other, things (radio calls, etc) happen fairly quickly for a student trying to make sure they do every position report they (thought they) need.
From memory the minimum requirement for PP was 10 hrs cross-country, minimum distance didn't come into it until commercial level.


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## DarrenW (May 31, 2018)

fubar57 said:


> I'm not seeing any 109s, 190s or -39s here people. JK ....I wish I had learned to fly when I had the chance



You are absolutely right Fubar, from this point further I will refrain from talking further about the P-39's abilities in the Pacific. Just want to take a moment though to thank Parsifal and XBe02Drvr for their candid and interesting opinions concerning both axis victories and Yoshino's demise. Now on to the Nazi stuff!


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## KiwiBiggles (May 31, 2018)

DarrenW said:


> You are absolutely right Fubar, from this point further I will refrain from talking further about the P-39's abilities in the Pacific. Just want to take a moment though to thank Parsifal and XBe02Drvr for their candid and interesting opinions concerning both axis victories and Yoshino's demise. Now on to the Nazi stuff!


Personally, I would welcome a break from the endless P-39 discussions.

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## XBe02Drvr (May 31, 2018)

KiwiBiggles said:


> Personally, I would welcome a break from the endless P-39 discussions.


Ditto!


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## P-39 Expert (Jun 1, 2018)

XBe02Drvr said:


> Those figures are for a P-39N, which had 225 more HP and somewhat less weight than the D. Besides, any previous experience the Japanese had against the P-39 was most likely meeting them and bouncing them as they struggled to intercept an incoming raid with very little warning.
> Cheers,
> Wes


Correct, the P-39N was a much better climber than the earlier D,F,K and L with the earlier -35 engine.


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## Greg Boeser (Jun 1, 2018)

XBe02Drvr said:


> Poor Yoshino! He didn't have access to your sources. In fact, I believe Koga and his Zero weren't yet embarked on their carrier that day.
> Cheers,
> Wes


9 June 1942. Koga and his Zero were upside down in the muskeg and had been there four days. (Remember, Akutan Island is on the other side of the dateline.)

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## XBe02Drvr (Jun 1, 2018)

Greg Boeser said:


> 9 June 1942. Koga and his Zero were upside down in the muskeg and had been there four days. (Remember, Akutan Island is on the other side of the dateline.)


Oops, my bad! I somehow got the idea in my thick head that the Yoshino event happened in April before Coral Sea and Midway. Guess I better wake up and pay attention!
Cheers,
Wes


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## Greg Boeser (Jun 1, 2018)

Although a handful of P-39s from the 36th FS went up to Moresby in early April, 1942, they really didn't see much action until the whole squadron and their supporting ground crews got there near the end of the month. First kills credited 30 April 1942. Yoshino was the victim of the first withdrawal escort mission flown in the SWPA. Up to that time the B-26s of the 22nd BG and the B-25s of the 3rd BG were flying unescorted. The 3rd BG had been mauled by Zeroes in back to back missions in late May, losing eight B-25s in two missions. So the Tainan pilots were conditioned to having their way with the unescorted bombers especially when they had to climb to get back over the Owen Stanleys. The 9 June mission was the first time friendly fighters were on hand to scrape the pursuers off so the bombers could get over the mountains unmolested.

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## P-39 Expert (Jun 2, 2018)

KiwiBiggles said:


> Personally, I would welcome a break from the endless P-39 discussions.


The title of the thread is "P-39 vs. German Fighters", no?


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## FLYBOYJ (Jun 2, 2018)

P-39 Expert said:


> The title of the thread is "P-39 vs. German Fighters", no?


Yes, and sometimes we allow discussion to go off kilter - how far this goes? This is a function of the admins and moderators.

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## wuzak (Jun 2, 2018)

P-39 Expert said:


> The title of the thread is "P-39 vs. German Fighters", no?



The discussion is still about the P-39, mainly, so that should make you happy!


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## jmcalli2 (Jun 9, 2018)

XBe02Drvr said:


> Those figures are for a P-39N, which had 225 more HP and somewhat less weight than the D. Besides, any previous experience the Japanese had against the P-39 was most likely meeting them and bouncing them as they struggled to intercept an incoming raid with very little warning.
> Cheers,
> Wes


Sounds good to me.


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## Barrett (Sep 30, 2018)

Sidebar: Just received a review copy of the latest in the Osprey "Duel" series: P-39/400 v. A6M2. Amazingly enough, the Bells broke even at 15-15 in New Guinea though of course they claimed 5-6 times as many.


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## P-39 Expert (Sep 30, 2018)

Not bad for green pilots up against Japan's best.


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## MIflyer (Sep 30, 2018)

Yes, the Osprey P-39 Aces book says much the same thing.

Of course Guadalcanal was the big problem. They were at even more of a disadvantage there and I think the P-400 reliability suffered from being shipped over the ETO and then down to the Solomans, as well as being equipped with RAF oxygen systems that the USAAF system could not support.

Interesting item in the P-39 Aces book. Buzz Wagner led a force of P-39's up the coast of New Guinea to attack Japanese seaplane bases and got into a huge furball of a fight in which both sides lost equal numbers. But that was a few days before the Battle of the Coral Sea, and one of the IJN's problems was inadequate recon seaplane support to their fleet. The IJN HQ tasked their seaplane units in the area and they replied that they were not in a position to help. Whether planned to help the naval engagement or not, the P-39's shot up those seaplane bases at just the right time.

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## XBe02Drvr (Sep 30, 2018)

MIflyer said:


> Whether planned to help the naval engagement or not, the P-39's shot up those seaplane bases at just the right time.


Sarah & Dippity!

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## parsifal (Oct 1, 2018)

P-39s never even came close to shooting down 15 Zekes over Moresby. Try a maximum of 7, but probably closer to 5, 

Ratios for overall P-39/A6M losses are better. All up losses are around 30 for the Zekes to about 60 for the P-39s, though some sources say many more.

.


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## P-39 Expert (Oct 2, 2018)

parsifal said:


> P-39s never even came close to shooting down 15 Zekes over Moresby. Try a maximum of 7, but probably closer to 5,
> 
> Ratios for overall P-39/A6M losses are better. All up losses are around 30 for the Zekes to about 60 for the P-39s, though some sources say many more.
> 
> .


How do you figure?


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## XBe02Drvr (Oct 2, 2018)

P-39 Expert said:


> How do you figure?


Per recorded Japanese losses, most likely.


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## P-39 Expert (Oct 2, 2018)

XBe02Drvr said:


> Per recorded Japanese losses, most likely.


Who knows how accurate their records are?


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## fubar57 (Oct 2, 2018)

As accurate as American, British, German and Russian records I imagine

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## XBe02Drvr (Oct 2, 2018)

P-39 Expert said:


> Who knows how accurate their records are?


Who knows? Shinpachi maybe?
Since the records were for their own administrative and maintenance purposes with probably no thought of public exposure or future publication, they're probably as accurate as they possibly could be under the circumstances. Propaganda not likely an issue.
Cheers,
Wes

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## DerAdlerIstGelandet (Oct 2, 2018)

P-39 Expert said:


> Who knows how accurate their records are?



What else do you have to go off of?


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## XBe02Drvr (Oct 2, 2018)

DerAdlerIstGelandet said:


> What else do you have to go off of?


American claims, of course! Ha, ha!

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## Peter Gunn (Oct 2, 2018)

P-39 Expert said:


> Who knows how accurate their records are?



Why are Japanese records always called into question? As Wes said, they had their own maintenance and administrative needs, what's to be gained by lying? I doubt any staff officer wanted to get caught telling his boss they had plenty of XYZ aircraft left when the reality was only half or less. Seppuku comes to mind if the general found out.


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## XBe02Drvr (Oct 2, 2018)

Hey, I just noticed I've been promoted to Airman 1st Class. What a non-sequitur! Airman is an E-3; Petty Officer 1st Class is an E-6. Does that make me an E-9? Or an E-4 1/2? Now if you want to do the sensible thing, and rate me AP (Airplane Pilot) 1st Class, that would be eagerly accepted! (My apologies to all the ancient members of that long abolished rate who are rolling over in their graves at this travesty.) I await with trembling heart my fate.
Cheers,
Wes

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## Peter Gunn (Oct 2, 2018)

XBe02Drvr said:


> Hey, I just noticed I've been promoted to Airman 1st Class. What a non-sequitur! Airman is an E-3; Petty Officer 1st Class is an E-6. Does that make me an E-9? Or an E-4 1/2? I await with trembling heart my fate.
> Cheers,
> Wes



OMG!!! Me too!!! Surely a sign of the apocalypse...

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## fubar57 (Oct 2, 2018)

Are you entitled to this while logged in here?

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## DerAdlerIstGelandet (Oct 2, 2018)

fubar57 said:


> Are you entitled to this will logged in here?
> 
> View attachment 511661​



If I’m not paid, you are not paid...

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## gumbyk (Oct 2, 2018)

fubar57 said:


> Are you entitled to this will logged in here?
> 
> View attachment 511661​


Please tell me that those are starting pay grades...


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## soulezoo (Oct 2, 2018)

Uh, nope!

There's still E-1 and E-2 grades...
What happened to the minimum wage of $15 an hour? And considering (at least it was when I was on active duty) that you are "on" 24 hours a day, the pay shrinks considerably. And I don't recall getting overtime when working 6 14 hour shifts a week when in the sandbox.

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## soulezoo (Oct 2, 2018)

Oh, and that pay reflected is "base" pay and doesn't reflect BAH or BAS or clothing allowance.


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## DerAdlerIstGelandet (Oct 2, 2018)

soulezoo said:


> Uh, nope!
> 
> There's still E-1 and E-2 grades...
> What happened to the minimum wage of $15 an hour? And considering (at least it was when I was on active duty) that you are "on" 24 hours a day, the pay shrinks considerably. And I don't recall getting overtime when working 6 14 hour shifts a week when in the sandbox.



When did active duty get $15/hr?

Not when I was in...lol


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## soulezoo (Oct 2, 2018)

DerAdlerIstGelandet said:


> When did active duty get $15/hr?
> 
> Not when I was in...lol


They didn't/don't. That was a backhanded remark directed to Unions and Democrats demanding $15 an hour living wage for McDonald's burger flippers. I don't see them demanding $15 an hour for soldiers who do much more and suffer for it.

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## DerAdlerIstGelandet (Oct 2, 2018)

soulezoo said:


> They didn't/don't. That was a backhanded remark directed to Unions and Democrats demanding $15 an hour living wage for McDonald's burger flippers. I don't see them demanding $15 an hour for soldiers who do much more and suffer for it.



I recommend we follow the forum rules and keep the left vs. right, liberal vs. conservative, and Democrat vs. Republican BS off the forum.

Besides they are all one in the same, regardless of what they each think.

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## parsifal (Oct 2, 2018)

Ive based it on a Pacific wrecks article about the air war over New guinea 1942 and part of 1943 . If P-39s managed to improve their dismal performance after those dates, then maybe there is some substance to the claims.

Basing losses on claims data for either side is very unreliable because they are so often demonstrably wrong. that's as true for the Japanese as it is for anyone. The thing I like about the Pacific wrecks stuff is that it is overwhelmingly based on sources other than claims....usually own side loss records.

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## Greg Boeser (Oct 2, 2018)

parsifal said:


> P-39s never even came close to shooting down 15 Zekes over Moresby. Try a maximum of 7, but probably closer to 5,
> 
> Ratios for overall P-39/A6M losses are better. All up losses are around 30 for the Zekes to about 60 for the P-39s, though some sources say many more.





Greg Boeser said:


> Between April and November 1942 in operations over New Guinea, Rabaul and Northern Australia, 81 Allied aircraft shot down can be directly attributed to Tainan pilots - 17 Kittyhawks/Warhawks, 38 P-39/P-400s, five A-24s, one Hudson, 10 B-25s, 5 B-26s, 5 B-17s.


Tainan lost 11-13 pilots to P-39s during this period.

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## XBe02Drvr (Oct 2, 2018)

Greg Boeser said:


> Tainan lost 11-13 pilots to P-39s during this period.


What source data?


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## tyrodtom (Oct 2, 2018)

fubar57 said:


> Are you entitled to this while logged in here?
> 
> View attachment 511661​


When I was in the USAF eons ago, 1965, E-3 was called airman 2nd class, and my base pay was about $140 a month.


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## XBe02Drvr (Oct 2, 2018)

soulezoo said:


> I don't see them demanding $15 an hour for soldiers who do much more and suffer for it.


Let's face it; you sign the papers, raise your right hand and swear the oath, you are trading citizenship for indentured servitude. Civilian standards, expectations, and privileges no longer apply. Some folks luck out and achieve a near civilian lifestyle, others bust their hump and get nothing but shat upon. Who said life is fair?
Cheers,
Wes

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## XBe02Drvr (Oct 2, 2018)

soulezoo said:


> There's still E-1 and E-2 grades...
> What happened to the minimum wage of $15 an hour?


Seaman Recruit, (E-1), boot camp 1970: $87/Mo. Upon graduation, I got instant advance to Airman (E-3), $150/Mo, because of prior education. Found out after I was in, that if I'd told my recruiter about my 2 years bus driving experience and childhood tractor driving, I would have gone in as an instant E-5 SeaBee. Apparently they were desperate for all kinds of drivers and equipment operators, but nobody from Great Lakes RTC was getting orders to SeaBee billets. They must have had their own separate pipeline. IIRC E-5 back then was circa $255/Mo, and I missed out on some of the world's garden spots, such as Cam Ranh Bay, the Mekong Delta, and Diego Garcia.
Cheers,
Wes


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## XBe02Drvr (Oct 2, 2018)

fubar57 said:


> Are you entitled to this while logged in here?
> 
> View attachment 511661​


Hell, that's more than I live on right now. Guess I outta go re-up!

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## parsifal (Oct 2, 2018)

Greg Boeser said:


> Tainan lost 11-13 pilots to P-39s during this period.




All up losses for Zekes in that critical 6month period March to August were about 30-35 so I can accept that as a result of those aircraft losses their pilot losses in total would be about 13-15. Its a stretch however, to claim all those losses were due to the p-39s. The Japanese losses includes losses to all causes. Many of the Japanese losses were unrelated to enemy air action. P-39 total losses in air combat were somewhat higher than IJN Zeke losses, which sounds like the P-39 was comparable to the Zeke, based on loss rates, but really isn't. The Japanese were on the attack, having to deal with flak weather and a mountain range to a much greater extent than either of the US FGs, and from an advanced strip that was much more primitive than those being used in Moresby. Many of the Zeke losses were to the defensive guns of the Allied medium bombers that continued to pound the advance airbases at Lae in particular, and a significant number of Japanese pilots were lost in accidents due to the deteriorating conditions at Lae.

It is highly unlikely that this number of pilots were lost to P-39s alone.

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## XBe02Drvr (Oct 3, 2018)

parsifal said:


> The Japanese were on the attack, having to deal with flak weather and a mountain range to a much greater extent than either of the US FGs,


And, due to lack of effective warning, the P-39s mostly entered combat with an altitude and speed disadvantage (bounced from 6 o'clock high while in an intercept climb), not the best scenario to display the Airacobra's stronger points. Ask Biff what that means in a lackluster mount. An Eagle surprising a Phantom, maybe?
Cheers,
Wes


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## CORSNING (Oct 3, 2018)

Page 15, Post #282:
P-40 vs. Yak-1 vs. Hurricane

What I am saying here is, the P-39 was never given the chance to be
like the other USAAF fighters. Even so, it was no slouch. It just could not
go up high where all the other AF fighters designated for such could.


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## KiwiBiggles (Oct 3, 2018)

CORSNING said:


> Page 15, Post #282:
> P-40 vs. Yak-1 vs. Hurricane
> 
> What I am saying here is, the P-39 was never given the chance to be
> ...



The enemy unfairly insisted on fighting at altitudes where the P-39 couldn't compete?

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## CORSNING (Oct 3, 2018)

KiwiBiggles said:


> The enemy unfairly insisted on fighting at altitudes where the P-39 couldn't compete?


For the most part you are right sir. North Africa and the Eastern Front of Russia are not
two of these areas!


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## parsifal (Oct 3, 2018)

XBe02Drvr said:


> And, due to lack of effective warning, the P-39s mostly entered combat with an altitude and speed disadvantage (bounced from 6 o'clock high while in an intercept climb), not the best scenario to display the Airacobra's stronger points. Ask Biff what that means in a lackluster mount. An Eagle surprising a Phantom, maybe?
> Cheers,
> Wes


The defences at Moresby certainly had some problems with the shadow effect of the owen Stanleys, however ways were found to over come this problem. Most American sources claim there was no radar at Moresby until very late in the year, but in fact radar had been deployed from the beginning of march. it was not very effective at the beginning, but did improve. 

The p-39s did receive advanced warning, usually from 'coast watchers" embedded in the known approach route s from lae to Moresby. Generally, even with plenty of warning they were still ineffective.

The Japanese never had any radar at Lae, and nothing to compare in terms of the ground based observers. The allies got quite good at exploiting this , using their level bombers to pound the airstrip from very low altitude approaches . Quite a number of Zekes were lost in landing/take off accidents because of this .

P-39s acted basically as targets for the Japanese to shoot at whilst other elements of the Allied arsenal did the real heavy lifting

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## CORSNING (Oct 3, 2018)

P-39s acted basically as targets for the Japanese to shoot at whilst other elements of the Allied arsenal did the real heavy lifting[/QUOTE]

*Parsifal, please tell me you did not say that. The P-39 especially after the "N" was nobody's fool
under 5,000 m. IN 1943,*

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## parsifal (Oct 3, 2018)

Elsewhere perhaps, but not over Moresby.

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## XBe02Drvr (Oct 3, 2018)

CORSNING said:


> Even so, it was no slouch. It just could not
> go up high where all the other AF fighters designated for such could.


Those impressive P-39 numbers were for the N model, too late for New Guinea, and had more horsepower and and less weight than the early models in Moresby. Apples and oranges. If they had been available for early days things might have been a bit different.
Cheers,
Wes

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## XBe02Drvr (Oct 3, 2018)

Tagas said:


> Your kidding me right?......lol Why do you think the russians liked them so much.......


Their theater was tailor made for the later N and Q P-39s, fast movers in the weeds, nice control at high speed and high "G" once the CG issues were fixed, and a flying arsenal to boot. And a tough, abuse-tolerant motor with much longer TBO than indigenous Soviet engines.
Not relevant to the D model in New Guinea.
Cheers,
Wes

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## Shortround6 (Oct 3, 2018)

Some of those numbers look suspiciously high. Higher than the numbers shown in the tests at Spitfire performance? 
And those number were done with planes that weighed less than they should have. The only way you get a P-39N down to 7300lbs is to fly with less than full internal tanks. For some weird reason even the test of the N seems to show abnormally high climb rates compared to the M and the Q, They changed reduction gears and props between the M and N and that might account for it? But then they mounted a single 50 cal under each wing and yanked the .30s and the climb fell back down to just about the level of the M. We are talking about a 400 fpm change in both directions at some altitudes.


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## Stig1207 (Oct 4, 2018)

It's also worth noting that the P-39 experience on the Eastern Front, is based on anecdotal evidence, aces scores and so forth. Has anyone actually seen any figures for claims or credits for the number of enemy aircraft shot down by Russian flown P-39s?


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## Schweik (Oct 4, 2018)

Greg Boeser said:


> Parsifal,
> Ruffato uses the Kodochosho records of all IJN air units in the Southeast Area to make his assessments. He does not rely on just US and Australian wartime claims, but compares claims vs reported losses of both sides, giving a score of claims vs actual losses. You should read it. He's an Italian so has no iron in the fire.



Can you summarize some of his stats for 1942? By type etc.?


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## fubar57 (Oct 4, 2018)

Schweik said:


> Can you summarize some of his stats for 1942? By type etc.?



I'd like to know where to read it in its entirety.


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## CORSNING (Oct 4, 2018)

Shortround6 said:


> Some of those numbers look suspiciously high. Higher than the numbers shown in the tests at Spitfire performance?
> And those number were done with planes that weighed less than they should have. The only way you get a P-39N down to 7300lbs is to fly with less than full internal tanks. For some weird reason even the test of the N seems to show abnormally high climb rates compared to the M and the Q, They changed reduction gears and props between the M and N and that might account for it? But then they mounted a single 50 cal under each wing and yanked the .30s and the climb fell back down to just about the level of the M. We are talking about a 400 fpm change in both directions at some altitudes.



OK then, go to WWII Aircraft Performance
Now click on the P-39N-1 section that clearly states its ability to climb
initially at 7,301 lbs. at a rate of 3980 fpm. and 4360 fpm at 7,500 ft.

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## KiwiBiggles (Oct 4, 2018)

CORSNING said:


> OK then, go to WWII Aircraft Performance
> Now click on the P-39N-1 section that clearly states its ability to climb
> initially at 7,301 lbs. at a rate of 3980 fpm. and 4360 fpm at 7,500 ft.


You missed out the quote below the results table:

"Prestone temperature does not meet Air Corps requirements in climb"​I bet you could get even better climb results in other aircraft if you didn't mind heat-soaking your engine.


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## Shortround6 (Oct 4, 2018)

CORSNING said:


> OK then, go to WWII Aircraft Performance
> Now click on the P-39N-1 section that clearly states its ability to climb
> initially at 7,301 lbs. at a rate of 3980 fpm. and 4360 fpm at 7,500 ft.




And yet we have the test of the P-39M with the same engine but different reduction gear and prop climbing hundreds of fps slower and not only a test of the P-39Q-5 (using the same engine and prop?) climbing hundreds of feet slower. We have a note that says the external guns on the XP-63 cost about 110fps in climb or about the smallest difference that could be measured and they didn't expect the change on the P-39Q to be much different.

we also have two charts
http://www.wwiiaircraftperformance.org/P-39/p-39q-25-1400.jpg
http://www.wwiiaircraftperformance.org/P-39/P-39Q-30-1400.jpg

That show later P-39Qs (same engine as the N) with two different props and without guns and weighing 7600lbs not getting over 3800fpm in climb when using WEP

Leaving us to wonder where did that P-39N-1 get that extra 400-500fpm of climb from? 

I would also note that power available for maneuvering (maintaining speed in a Hi G turn) is going to be much closer to the climb power than the level speed power. By that I mean look at the chart for the P-39Q-25. at 10,000ft (3048 meters) half of the advantage (difference between WEP and military power) of of WEP goes away by slowing down from max level speed to climb speed. The P-39s ability to fight/maneuver at 5000 meters, even in the later versions against the 109 and 190 is a bit suspect. Do a firing pass yes, but any hard maneuvering is going to result in either a slow airplane or the loss of thousands of feet of height.

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## Schweik (Oct 4, 2018)

They could have easily tested it with 30 or 40 gallons less fuel or just removed wing guns or the internal starter or something.


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## Greg Boeser (Oct 4, 2018)

fubar57 said:


> I'd like to know where to read it in its entirety.


Try here:
Eagles of the Southern Sky

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## fubar57 (Oct 4, 2018)

Many thanks Greg


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## Glider (Oct 4, 2018)

I always thought that one of the differences between the P39N and others was a significantly reduced fuel load, by about a third or am I wrong on this? 
I mention this as I don't recall seeing a successful fighter having its fuel load reduced, added certainly, but not reduced


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## Greg Boeser (Oct 4, 2018)

Depends what you are after. Later P-39 makes a great point defense fighter. Not a very good long range escort. By 1943 the western allies were on the offensive, pushing the German defenses back. No place for a short-legged fighter to shine.


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## XBe02Drvr (Oct 4, 2018)

Shortround6 said:


> The P-39s ability to fight/maneuver at 5000 meters, even in the later versions against the 109 and 190 is a bit suspect.


What do you expect? The Cobra's forte was speed in the weeds and 16,000 feet was in the upper limits of its combat performance envelope. So what? That wasn't where the action was. Dogfighting at 15-16K wasn't going to keep the Stukas off the troops.


Shortround6 said:


> Leaving us to wonder where did that P-39N-1 get that extra 400-500fpm of climb from?


Judging from the footnotes pointed out above, I would guess it came from reduced fuel load and cooking the engine to get flashier numbers. Everything Larry Bell did seemed to smell of flash over substance.
Also bear in mind, early Ns had reduced fuel tankage per Soviet request, while later Ns and most all Ps and Qs went back to the larger capacity. And many were field modded to increase or decrease tankage.
Cheers,
Wes


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## XBe02Drvr (Oct 4, 2018)

Greg Boeser said:


> allies were on the offensive, pushing the German defenses back. No place for a short-legged fighter to shine.


Unless said fighter is providing low cover for advancing armor and mechanized infantry while operating from forward airstrips, Soviet style.
Cheers,
Wes


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## XBe02Drvr (Oct 4, 2018)

Greg Boeser said:


> Later P-39 makes a great point defense fighter.


Even the hottest early N models with the reduced fuel would have been a nonstarter at ETO altitudes against escorts with two speed or two stage superchargers or turbos.
Cheers,
Wes

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## CORSNING (Oct 5, 2018)

XBe02Drvr said:


> Even the hottest early N models with the reduced fuel would have been a nonstarter at ETO altitudes against escorts with two speed or two stage superchargers or turbos.
> Cheers,
> Wes



OK,....In all my posts on this forum about the later P-39s with the V-1710-83 engine
I am pretty sure I never said it was a world beater even when it was first delivered in
November 1942. Although at that time until late 1943 it could hold its own against 
most first line Axis fighters up to 5,000 m. provided it was flown to its strengths.

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## special ed (Oct 5, 2018)

In the 1950s I was a Civil Air Patrol cadet as a teenager. We met at the New Orleans Lakefront airport. There were some old hands working there who remembered P-39s coming through. They were on their way to some place to go to Africa. I was told the ground run time in the heat was 20 minutes. If you weren't on your takeoff roll you were to shut down. The problem was, the temp was still in the green so if you were next the pilot thought he was good to go, however on climb out the engine overheated and quit. I was told the Cajuns who lived in the swamp knew where every crash was and made government money for body recovery.

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## Shortround6 (Oct 5, 2018)

CORSNING said:


> OK,....In all my posts on this forum about the later P-39s with the V-1710-83 engine
> I am pretty sure I never said it was a world beater even when it was first delivered in
> November 1942. Although at that time until late 1943 it could hold its own against
> most first line Axis fighters up to 5,000 m. provided it was flown to its strengths.


 And would the strength of the P-39 at 5000meters (16,400ft) be to dive down to 3000meters upon sighting the German fighters? 
Being a bit sarcastic, I will agree that the P-39 could display good performance at 3000 meters and below but 5000 meters is really pushing things. 






From Mike Williams website Spitfire performance. 
The P-39M-N-Q all used the same power section or had the power curves. they varied in reduction gear used and propellers used. 
Unless the planes are flying level and at high speed much of the WEP power advantage goes away above 3000 meters. Leaving high level speed and diving as the only real strengths of the P-39.


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## CORSNING (Oct 5, 2018)

Shortround6 said:


> And would the strength of the P-39 at 5000meters (16,400ft) be to dive down to 3000meters upon sighting the German fighters?
> Being a bit sarcastic, I will agree that the P-39 could display good performance at 3000 meters and below but 5000 meters is really pushing things.
> View attachment 512061
> 
> ...



*SR6, it looks like the WEP advantage lasts up to about 5,000 m. on the graph
you posted to me. I am just saying that I agree that the P-39 variants were
never a high or medium high altitude first class fighter, agreed. But down in
the lower regions the later versions held there own.*


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## Shortround6 (Oct 5, 2018)

The WEP advantage lasts (barely) for straight and level flight at full speed. 
Take another look at the power chart in the middle of the graph. The solid line is the WEP power available at climb speed around 170-175mph at sea level and just under 200mph at 15,000ft. The dashed lines show the power available at higher speeds, the extra boost from the RAM air at 330-370mph. 

Now say your P-39 has just climbed hard up to 12,500ft and is doing about 200mph and you level out. You don't have a bit over 1300hp, you have a bit over 1100hp due to lack of ram. _AS _you _accelerate_ you pick up RAM effect and if you accelerate long enough you will get to that 1300hp level and the just about 400mph speed. Now how long does it take you to accelerate from 200mph to 375mph or above? If you bank you loose lift and have to use a slightly higher angle of attack crating drag, If you really bank and turn you will bleed off speed and are never going to reach that high area of the WEP. 
At 12,500ft the WEP is worth about 150fps in climb vs the 750fpm or so it was worth at lower altitudes. At 5000 meters it is worth 3-5mph in level flight, if that. Not something to pin your chances of either victory or survival on.

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## XBe02Drvr (Oct 6, 2018)

Shortround6 said:


> _AS _you _accelerate_ you pick up RAM effect and if you accelerate long enough you will get to that 1300hp level and the just about 400mph speed.


Good trainer for transition to a 1st generation jet?


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## P-39 Expert (Oct 6, 2018)

Shortround6 said:


> Some of those numbers look suspiciously high. Higher than the numbers shown in the tests at Spitfire performance?
> And those number were done with planes that weighed less than they should have. The only way you get a P-39N down to 7300lbs is to fly with less than full internal tanks. For some weird reason even the test of the N seems to show abnormally high climb rates compared to the M and the Q, They changed reduction gears and props between the M and N and that might account for it? But then they mounted a single 50 cal under each wing and yanked the .30s and the climb fell back down to just about the level of the M. We are talking about a 400 fpm change in both directions at some altitudes.


Once again, ALL the planes tested in official performance tests (not propeller comparison tests etc.) were lighter than their published weights reflecting an average fuel weight during the test flight. The British used 95% of takeoff weight as their "corrected" weight to reflect fuel burned. The P-39N test was a standard test and the figures should be respected.


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## XBe02Drvr (Oct 6, 2018)

Shortround6 said:


> Now say your P-39 has just climbed hard up to 12,500ft and is doing about 200mph and you level out. You don't have a bit over 1300hp, you have a bit over 1100hp due to lack of ram.


So if you have time and are not immediately bounced, get "on the step" by continuing your climb to 13,000, then accelerating in a shallow descent back down to 12.5. I've done that in 99s and 1900s, as PT6 engines are somewhat sensitive to ram effect.
Cheers,
Wes


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## XBe02Drvr (Oct 6, 2018)

P-39 Expert said:


> The P-39N test was a standard test and the figures should be respected.


Yes, and the good guys wear white hats and always win!
Cheers,
Wes

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## Shortround6 (Oct 6, 2018)

XBe02Drvr said:


> So if you have time and are not immediately bounced, get "on the step" by continuing your climb to 13,000, then accelerating in a shallow descent back down to 12.5. I've done that in 99s and 1900s, as PT6 engines are somewhat sensitive to ram effect.
> Cheers,
> Wes




You could do that. However the British figured the Spitfire V, not usually noted for being the fastest accelerating fighter plane, took almost two minutes to go from just over 200mph to max speed. The P-39 was better, it was often about the middle of the pack among US fighters for acceleration but even a full minute is an eternity in combat. 

I will fully admit that the WEP changes things a lot for the P-39 at lower altitudes where it is available regardless of the speed of the aircraft. But once above 3000 meters it becomes much less of a factor in anything except straight line flight. The claim of it being effective at 5000 meters is rather dubious.


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## Shortround6 (Oct 6, 2018)

P-39 Expert said:


> The P-39N test was a standard test and the figures should be respected.



I would respect it a lot more if the tests for the aircraft preceding it, which used the same engine but a different prop and the planes that followed it which used the same engines but different props on some, were anywhere near it. of these five airplanes/tests/charts the weight of the aircraft varies by 400lbs form lightest to heaviest. From lightest to heaviest the weight difference is 4.1% and yet the lightest plane (the N) shows a best climb of 380fpm (10% over the next best and even more over the rest. The other four aircraft show weight variation of about 200lbs and yet the climb difference is barely over 100fpm. The two late model Qs have no guns in or under the wings and would have less drag than the N even if a few hundred pounds heavier. Even a test of the P-39Q-5 at 7871lbs (6th test) with no wing guns shows only a 200-300fpm fall off in climb even with an engine not quite making full power (55in) at 3600-3700fpm. 

So if you have 5 out 6 planes closely clustered in weight and using the same power engine and closely clustered in climb and the 6th plane using the same engine and only slightly less weight showing a major increase in climb rate what are you to believe? 
What guarantee do you have that a plane 5 or 10 serial numbers different than the test plane is going to act like the test plane or act like the other 5 planes tested?


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## CORSNING (Oct 6, 2018)

Shortround6 said:


> So if you have 5 out 6 planes closely clustered in weight and using the same power engine and closely clustered in climb and the 6th plane using the same engine and only slightly less weight showing a major increase in climb rate what are you to believe?
> 
> *That it was a good idea to take the four paint chippers out of
> the wings like the Russians did?...*

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## Shortround6 (Oct 6, 2018)

Problem is that three of the P-39Qs tested didn't have any guns in or under the wings and the plane that did post those wonderful numbers did have the _paint chippers _installed. 

Perhaps the Russians goofed and the wing guns actually increase the rate of climb 

the four paint chippers and their ammo (normal load, not full) weighed less than 175lbs.

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## Greg Boeser (Oct 6, 2018)

XBe02Drvr said:


> So if you have time and are not immediately bounced, get "on the step" by continuing your climb to 13,000, then accelerating in a shallow descent back down to 12.5. I've done that in 99s and 1900s, as PT6 engines are somewhat sensitive to ram effect.
> Cheers,
> Wes


I seem to recall reading this instruction in a pilot's manual to increase cruise efficiency.


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## CORSNING (Oct 6, 2018)

Perhaps the Russians goofed and the wing guns actually increase the rate of climb 

*Wow SR6, you might be on to something there. I'm going to have to
go into deep research now. .*..

Actually, we are on the same page here. If you look at all the
P-39 tests they all mention the overheating problem when boosted.
At no time is it mentioned that the engine was not able to take
the punishment. It just says the USAAF didn't approve of it.

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## Glider (Oct 6, 2018)

CORSNING said:


> Perhaps the Russians goofed and the wing guns actually increase the rate of climb
> 
> *Wow SR6, you might be on to something there. I'm going to have to
> go into deep research now. .*..
> ...



An obvious observation.
If the engine could take the punishment, then it wouldn't be a problem. If the USAAF considered it to be a problem, then overheating the engine must have had consequences. I don't pretend to know what those consequences were, but I think it would be unwise to pretend that there were no consequences.

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## Shortround6 (Oct 6, 2018)

The USAAC had certain standards for safety reasons. IN many cases to build a cushion or reserve. If you are running into the "red zone" in Nov over Buffalo NY you might only be slightly in the red zone and there would be no damage. One test says the coolant was at 126 degrees C with the out side air at -12 degrees C at 12,000ft. Now maybe the engine (and the oil) could survive running at 126 degrees C for several minutes (or even more) but the USAAC figured that 126C would wind up being 152 degrees C on a "standard" hot day (100 degrees F at ground level) or for those of us Celsius challenged individuals that is about 305 degrees Fahrenheit. 

So you have a plane that will climb like a bandit in the Russian winter and needs to level off periodically to let the coolant get down to just over boiling when operating in the tropics or warm climates. Good luck getting the German and Japanese pilots to give you "cool down breaks" in combat.

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## XBe02Drvr (Oct 7, 2018)

Glider said:


> If the USAAF considered it to be a problem, then overheating the engine must have had consequences. I don't pretend to know what those consequences were, but I think it would be unwise to pretend that there were no consequences.


The test reports don't tell you whether the engine on that hot performing P-39N1 whose coolant temp "didn't conform to USAAF standards" suffered an engine failure in some subsequent flight or had to have its engine pulled early for overhaul. If the test was done in Niagara NY or Moscow RFSSR in winter, then the engine could probably take that abuse with limited hidden damage. With MSL OAT 60°-70°F below ISA, your density altitude is going to be only about 3/4 of your barometric altitude, and your engine's going to have more power and your radiators more efficiency, and the risk of thermal runaway much reduced. In fact the plane's going to think it really is at 3,000 meters when it's actually at 4,000.
Now all it takes is for the conversion of the raw measurements to ISA conditions to get lost in the shuffle, and there's your anomalous "hot Cobra".
Cheers,
Wes

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## XBe02Drvr (Oct 7, 2018)

Shortround6 said:


> But once above 3000 meters it becomes much less of a factor in anything except straight line flight.


Under those conditions you gain total energy faster by climbing than by trying to accelerate from slow speed in level flight. The extra 500 feet can't take more than 20-30 seconds at the outside, and then gravity is helping you accelerate and enhancing the "bootstrap effect" of your increasing ram as your speed builds.
All of this is dependent on how sensitive your induction system is to ram effect. Flow losses due to filters, screens, and awkward ducting can of course impact gains from ram effect. I've been told this was part of the Spitfire V's problem.
Cheers,
Wes


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## Shortround6 (Oct 7, 2018)

XBe02Drvr said:


> The test reports don't tell you whether the engine on that hot performing P-39N1 whose coolant temp "didn't conform to USAAF standards" suffered an engine failure in some subsequent flight or had to have its engine pulled early for overhaul. If the test was done in Niagara NY or Moscow RFSSR in winter, then the engine could probably take that abuse with limited hidden damage. With MSL OAT 60°-70°F below ISA, your density altitude is going to be only about 3/4 of your barometric altitude, and your engine's going to have more power and your radiators more efficiency, and the risk of thermal runaway much reduced. In fact the plane's going to think it really is at 3,000 meters when it's actually at 4,000.
> Now all it takes is for the conversion of the raw measurements to ISA conditions to get lost in the shuffle, and there's your anomalous "hot Cobra".
> Cheers,
> Wes



My conversions may be a bit on the sketchy side as I am using on old book for the temperature chart but at 12,000ft on a standard day (59 degrees F at sea level) the temperature at 12,000ft was supposed to be 16.21 degrees F or about -8.8 degrees C vs the -12 degrees C in the test. 

I do take your point though,


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## P-39 Expert (Oct 8, 2018)

None of the Allison powered fighters, nor the P-47 nor the Spitfire V met hot day cooling standards.


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## MiTasol (Oct 8, 2018)

Shortround6 said:


> From lightest to heaviest the weight difference is 4.1% and yet the lightest plane (the N) shows a best climb of 380fpm (10% over the next best and even more over the rest.



While I also consider the numbers suspect there is absolutely no doubt that if there are two identical aircraft with different weights the lightest will climb fastest.
Another factor is that the Q models had large nostrils for the fuselage 50 cals and those will have created drag and probably turbulence, both of which affect (reduce) performance.
A third factor is how well fitted the belly armour was. Having that 1/2 inch thick alloy plate hanging a mm low at the front would create a significant increase in drag


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## CORSNING (Oct 8, 2018)

Great information guys. Thank you all.


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## P-39 Expert (Oct 8, 2018)

Shortround6 said:


> I would respect it a lot more if the tests for the aircraft preceding it, which used the same engine but a different prop and the planes that followed it which used the same engines but different props on some, were anywhere near it. of these five airplanes/tests/charts the weight of the aircraft varies by 400lbs form lightest to heaviest. From lightest to heaviest the weight difference is 4.1% and yet the lightest plane (the N) shows a best climb of 380fpm (10% over the next best and even more over the rest. The other four aircraft show weight variation of about 200lbs and yet the climb difference is barely over 100fpm. The two late model Qs have no guns in or under the wings and would have less drag than the N even if a few hundred pounds heavier. Even a test of the P-39Q-5 at 7871lbs (6th test) with no wing guns shows only a 200-300fpm fall off in climb even with an engine not quite making full power (55in) at 3600-3700fpm.
> 
> So if you have 5 out 6 planes closely clustered in weight and using the same power engine and closely clustered in climb and the 6th plane using the same engine and only slightly less weight showing a major increase in climb rate what are you to believe?
> What guarantee do you have that a plane 5 or 10 serial numbers different than the test plane is going to act like the test plane or act like the other 5 planes tested?


There was actually a second climb test on that same P-39N #4400 about a month later on November 24 to record WEP climb which was not used on the original P-39N climb test. This climb test showed the expected increase in climb below critical altitude but the climb rate at 15000' (critical altitude for climb) was 3230fpm or only 110fpm lower than the previous test at the same 1060HP. Weight was only 27# more. The climb rate at 15000' was virtually the same on both tests, indicating neither test was a fluke and the plane climbed as advertised. Climbed faster than just about anything in '43 except a Spitfire IX.


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## Kevin J (Oct 9, 2018)

CORSNING said:


> Great information guys. Thank you all.


Maybe this can clear up the debate on just how good the P-39 really was when used correctly. You'll need to run this in google chrome for it to automatically translate.
P-39 Аэрокобра на советско-германском фронте


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## Shortround6 (Oct 9, 2018)

It is interesting but flawed, it doesn't really say how the planes were were used (tactics or combat situation) and relies on the rather dubious method of comparing the scores of the top aces. I am not trying to get into an argument about claiming or over claiming or anything like that.

The method is dubious because it fails to take into account the number of missions flown by the pilots of each type and number of times each pilot was actually engaged in combat. As an extreme example we have Eric Hartman who (according to wiki) He "flew 1,404 combat missions and participated in aerial combat on 825 separate occasions." to get is 352 victories. 
This article does not tell us how many combat missions the various pilots (of several air forces) flew or how many of those missions resulted in actual combat. 
The US in particular tended to rotate pilots out of combat after a fixed number of missions (although many extended their tours voluntarily or signed up up for a whole new tour, same with many British pilots, including the commonwealth). 

So if you have a Russian pilot who flew plane A on 250 missions and engaged in combat (fired guns?) 175 times and claimed 50 victories how does that prove that Plane A was better than Plane B that was flown by An american pilot 120 times and fired it's guns 75 times and shot down 30 planes? (made up numbers) 

Please note I am not trying to take anything away for Hartman or any of the pilots listed in the article. In many cases it was a testament to luck, skill and day in day out courage simply to survive 100 mission let alone several hundred. Shooting down substantial quantities of enemy aircraft is a whole different story.

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## P-39 Expert (Oct 9, 2018)

Kevin J said:


> Maybe this can clear up the debate on just how good the P-39 really was when used correctly. You'll need to run this in google chrome for it to automatically translate.
> P-39 Аэрокобра на советско-германском фронте


Am I going crazy or did that article repeat itself w few times in the body of text?

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## Shortround6 (Oct 9, 2018)

you are not crazy. More than few times.

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## P-39 Expert (Oct 9, 2018)

Shortround6 said:


> you are not crazy. More than few times.


But, I could still be crazy.

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## Kevin J (Oct 9, 2018)

Shortround6 said:


> It is interesting but flawed, it doesn't really say how the planes were were used (tactics or combat situation) and relies on the rather dubious method of comparing the scores of the top aces. I am not trying to get into an argument about claiming or over claiming or anything like that.
> 
> The method is dubious because it fails to take into account the number of missions flown by the pilots of each type and number of times each pilot was actually engaged in combat. As an extreme example we have Eric Hartman who (according to wiki) He "flew 1,404 combat missions and participated in aerial combat on 825 separate occasions." to get is 352 victories.
> This article does not tell us how many combat missions the various pilots (of several air forces) flew or how many of those missions resulted in actual combat.
> ...


You might like to try going through the entire website. There's a lot more detail in the P-40 section. IIRC there's a section on fighter tactics somewhere but its a long while ago that I found all this. IIRC, the Cobras used to fly in four pairs of two separated by 1000 feet of height with only two assigned the task of shooters, the rest acting as cover. It was called group area fighting tactics.

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## Ivan1GFP (Oct 11, 2018)

Kevin J said:


> Maybe this can clear up the debate on just how good the P-39 really was when used correctly. You'll need to run this in google chrome for it to automatically translate.
> P-39 Аэрокобра на советско-германском фронте



Thanks for the link.
Google Translate seems to have its problems in a few areas, but I can read enough of the original Russian to tell what was going on.
The second page was much more interesting than the first because it showed that the Soviets also ran into their share of problems and even lost quite a few experienced pilots because of the P-39's CoG and structural problems.
It appears to me that the P-39 appeared to do well in Soviet service because their standards tended to be much lower than those of the Western Allies.

- Ivan.

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## CORSNING (Oct 11, 2018)

Ivan1GFP said:


> It appears to me that the P-39 appeared to do well in Soviet service because their standards tended to be much* lower* than those of the Western Allies.
> 
> - Ivan.



Ivan, in a way you are correct. The Russians did not have the natural resources
available to them as many other nations had. Most of there aircraft exteriors
were wood and the engines available to them early in the war were very limited
in power.
If by lower you mean geared to the lower altitudes then you are absolutely
correct. If you mean their expectation of what they wanted out of there front
line fighters then I would reply, " No, I do not believe any of the warring nations
wished to settle for less than the nation's aircraft they had to oppose."


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## Ivan1GFP (Oct 11, 2018)

CORSNING said:


> Ivan, in a way you are correct. The Russians did not have the natural resources
> available to them as many other nations had. Most of there aircraft exteriors
> were wood and the engines available to them early in the war were very limited
> in power.
> ...



Hello Corsning,
I am not sure I can agree with your summary of the Soviet Union's resources of the time.
I believe most of their problems before the war was that although there WERE plenty of resources, there wasn't the industrial and educational background in the general population to support many industries.
Regarding low power aero engines, the United States wasn't doing much better at the time with its Allison as compared to the Soviet Klimov and Mikulin designs. None were that high powered initially.
Regarding radials, there are a lot more variation but I believe the general philosophy was way different and I don't believe I am knowledgeable to do more than speculate there.

Regarding low altitude versus high altitude supercharging, just keep in mind that the pre-war United States wasn't really doing any better. Along with a multi-stage supercharger that is needed for good altitude performance, there typically needs to be an intercooler and the two add a significant weight penalty and cost performance at lower altitudes. Neither is needed for aircraft that are basically used to support ground forces.

My actual comment about lower standards was more about the quality that the Soviets were willing to accept and produce. Many of their aircraft had serious problems and dangerous handling characteristics. The wooden aircraft structures you mentioned earlier had quite a few failures due to manufacturing issues. Their early fighters were hardly competitive and some had stability problems or were seriously underpowered. I don't think (slightly) inferior quality bothered them much because "Quantity has a quality all its own."
Basically, the Soviets were very good at building for war where peasant soldiers and pilots are cheap. They start with a pretty good design and build it to a mediocre standard and let the numbers overwhelm the opposition. Sooner or later some of these soldiers and pilots gain the experience to be very dangerous adversaries.
By this standard in comparison to an early LaGG fighter, an Airacobra looks pretty good despite CoG issues and structural failures.

- Ivan.

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## Ivan1GFP (Oct 11, 2018)

greybeard said:


> Hello!
> I was intrigued by reading of this interview with Golodnikov, especially by his mention about true performances of German fighters (color plus some correction of the text by me):
> 
> "_A. S. Nikolay Gerasimovich, if you look at any reference book, the superiority in speed of German aircraft [like] the Bf-109G and FW-190 is indisputable. Minimum 20-25 kilometers at low altitudes and up to 80-100 kilometers at high altitudes. And you say ours did not lag behind?
> ...



Someone might have addressed this already, but I believe All the folks at NII VVS were doing was converting from TAS to IAS.
Try a couple of the conversions. The numbers aren't too far off for TAS converted to IAS.

- Ivan.


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## CORSNING (Oct 12, 2018)

Back on topic, I agree that the P-39 (any version) was never a first
class fighter. It did help the US to hold the line in the Pacific in 1941,
1942 and early 1943. It was exactly what the Russians needed in
1942/1943.
I have a lot more to add but the Mrs. told me to get my...self in the
shower so that we can kick back for the evening.
See you guys tomorrow. As Ray (Trailer Park Boys) puts it the best,
"That's the way she goes boys, that's the way she goes."
Love you guys, Jeff

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## Ivan1GFP (Oct 13, 2018)

I am glad that Driver Education business got split off into its own thread.

I am not entirely certain this is on topic either, but here goes:
The Russian article also mentioned that the reduction in fuel capacity with the P-39N was requested by the Russians.
This is an interesting thing considering that the fuel load was only 120 Gallons before being reduced.
The already short range apparently didn't make a difference because the airfields were so close to the front lines and pilots were typically flying up to 3-4 missions in a day.
From that perspective, 1400 missions by Hartmann does not sound so extreme.

- Ivan.

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## P-39 Expert (Oct 15, 2018)

P-39 actually held lots of fuel when compared to European planes. More than the Spitfire and Me109 and more than a Fw190 based on gallons to displacement.

Incredibly the Russians didn't need that much gas for their missions and recommended the reduction. AAF probably went along with it since the primary role for the AAF in '43 was training and reduced fuel dovetailed with that mission.


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## CORSNING (Oct 15, 2018)

The P-39N and P-39Q-1 came from the factory with the capacity
to carry 87 US gallons of internal fuel. This gave the P-39s a practical
range of 360 mls. at 214 mph.


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## P-39 Expert (Oct 15, 2018)

Reduced from the original 120 gal. on the first 167 P-39Ns.


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## tomo pauk (Oct 15, 2018)

P-39 Expert said:


> P-39 actually held lots of fuel when compared to European planes. More than the Spitfire and Me109 and more than a Fw190 based on gallons to displacement.
> ...



Gallons per displacement don't tell us a lot, if anything. Gallons per power might be a better metrics?
However - Re.2001, 2005 and G.55 carried more fuel than the P-39, especially than the versions with reduced fuel.


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## CORSNING (Oct 15, 2018)

OK, I was just getting ready to unwind. Diana said, NO! 
Sorry family time, but I will come back with figures that
will add respect to the P-39 (later versions) tomorrow.


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## P-39 Expert (Oct 15, 2018)

Either way the P-39 with 120 gals held more than the Fw190.


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## Dimlee (Oct 15, 2018)

Ivan1GFP said:


> Hello Corsning,
> I am not sure I can agree with your summary of the Soviet Union's resources of the time.
> I believe most of their problems before the war was that although there WERE plenty of resources, there wasn't the industrial and educational background in the general population to support many industries.
> - Ivan.



Resources.
Industrial and educational background was on the lower level compared to more developed countries, indeed.
But still there was lack of raw materials - of some categories.. Many of those huge deposits which helped USSR to grow after WWII were not discovered yet. And those which were discovered were prohibitively expensive to develop due lack of infrastructure, energy generation, etc. Non-ferrous metals shipments of the lend lease program were very important.


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## Ivan1GFP (Oct 15, 2018)

Dimlee said:


> Resources.
> Industrial and educational background was on the lower level compared to more developed countries, indeed.
> But still there was lack of raw materials - of some categories.. Many of those huge deposits which helped USSR to grow after WWII were not discovered yet. And those which were discovered were prohibitively expensive to develop *due lack of infrastructure, energy generation, etc*. Non-ferrous metals shipments of the lend lease program were very important.



I don't believe you and I are disagreeing much. The Soviets had their own internal political issues at the time which were probably a greater concern to the leadership than keeping their air forces up to date. When one is more afraid of what a capable officer corps can accomplish than wanting to exploit those skilled (and possibly ambitious) officers, then there are problems. This is getting way off topic though.

- Ivan.


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## Ivan1GFP (Oct 15, 2018)

P-39 Expert said:


> Either way the P-39 with 120 gals held more than the Fw190.



Hello P-39 Expert,
What you are stating isn't really accurate.
The FW 190A through the A-7 and even early A-8 series had two fuel tanks as standard.
The Forward Tank was 233 Liters (61,5 USG)
The Middle Tank was 292 Liters (77.1 USG)
The Aft Fuselage Tank which was optional on some models became standard during the A-8 production run and added 115 Liters (33.3 USG).

So.... Early models would have had 138.69 Gallons and Late models would have had 169 Gallons of internal fuel.

Note also that the FW 190 series could carry a lot of external stores or fuel which the Airacobra could not.

- Ivan.


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## BiffF15 (Oct 15, 2018)

Ivan1GFP said:


> Hello P-39 Expert,
> What you are stating isn't really accurate.
> The FW 190A through the A-7 and even early A-8 series had two fuel tanks as standard.
> The Forward Tank was 233 Liters (61,5 USG)
> ...



You guys are much sharper than I on these two aircraft. My question is how did they stack up or compare range wise. I’m assuming the radial had a higher gallon per mile covered or greater fuel burn than the inline (V12) of the P39?

Cheers,
Biff


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## wuzak (Oct 15, 2018)

P-39 Expert said:


> P-39 actually held lots of fuel when compared to European planes. More than the Spitfire and Me109 and more than a Fw190 based on gallons to displacement.



Was looking for a Spitfire IX data sheet and found this - fuselage tank mods for a long range IX
http://www.spitfireperformance.com/spitfire9-fuelsystem-lr.jpg

I think the date is 1945, but I can't tell for sure.

The standard IX had 85 imperial gallons, which is 102 USG. Which is less than the 120USG that some P-39s had, but more than most P-39s had (87USG).

This long range Spitfire had 96 UKG forward of the pilot and 66 or 74UKG behind the pilot, depending if it had the standard or cut down rear fuselage.

MK VIIIs had 96 UKG forward tanks as standard and 13 UKG in each wing, for a total of 122UKG. This carried over to the XIV.

I'm not sure if IXs ever got the leading edge tanks. I suspect not. 

In any case, it appears that the Spitfire had more space where fuel could be added, even if that could cause stability issues (eg rear tanks).


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## wuzak (Oct 15, 2018)

BiffF15 said:


> You guys are much sharper than I on these two aircraft. My question is how did they stack up or compare range wise. I’m assuming the radial had a higher gallon per mile covered or greater fuel burn than the inline (V12) of the P39?
> 
> Cheers,
> Biff



Definitely had higher gallons per hour, mainly because they had more power.

Air miles per gallon depends on what that extra power does for speed.


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## BiffF15 (Oct 15, 2018)

wuzak said:


> Definitely had higher gallons per hour, mainly because they had more power.
> 
> Air miles per gallon depends on what that extra power does for speed.



Ranges for each? I’m curious as I’ve always looked at the Fw190 and Me109 as very short ranged or point defense fighters and if the P39 is similar it changes how I have historically perceived it.

Cheers,
Biff


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## XBe02Drvr (Oct 15, 2018)

wuzak said:


> Which is less than the 120USG that some P-39s had, but more than most P-39s had (87USG).


According to some of the sources referenced earlier in this thread, the 87 gallon Cobras were in the minority, being primarily the early marks of the N series and early Ds and prior models, many of which were retrofitted to higher capacity.
Cheers,
Wes


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## Greyman (Oct 15, 2018)

British figures for P-39D2 (V1710-63)

Petrol: 100 gallons
Take-off and climb to 15,000: minus 21.5 gallons
Range at most econ: 630 miles (minus 76 miles for every 5 min of combat)
Range at max weak mix: 450 miles (minus 54 miles for every 5 min of combat)

Combat: 3000 rpm and 60 inches

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## eagledad (Oct 15, 2018)

Wuzak

Per the Spitfire Mk XI, my sources indicate that the Mk XI converted from MK IX airframes did not have the leading edge wing tanks (about 50), the rest did (about 420). The wing tanks held 66.5 gallons each, giving a total tankage of 218 gallons total (85 in fuselage and 123 in wings)

Sources: Supermarine Spitfire by Peter Moss, Spitfire-The Story of a Famous Fighter by Bruce Robertson

Also if you look at the test of a Mk XI on Mike Williams' and Neil Stirling's site, you will find that the Aircraft had leading edge tanks.

FYI

Eagledad


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## wuzak (Oct 15, 2018)

eagledad said:


> Wuzak
> 
> Per the Spitfire Mk XI, my sources indicate that the Mk XI converted from MK IX airframes did not have the leading edge wing tanks (about 50), the rest did (about 420). The wing tanks held 66.5 gallons each, giving a total tankage of 218 gallons total (85 in fuselage and 123 in wings)
> 
> ...



I think there has been a misunderstanding.

The VIII and XIV had small, 13UKG, tanks housed inside the inner leading edge of the wing.

Theoretically those tanks could have been put into the IX as well. But I don't believe they were.

The XIs, the ones not converted from the IX, got a different wing with a different structure, which allowed the leading edge tanks to span most of the wing.


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## wuzak (Oct 16, 2018)

BiffF15 said:


> Ranges for each? I’m curious as I’ve always looked at the Fw190 and Me109 as very short ranged or point defense fighters and if the P39 is similar it changes how I have historically perceived it.
> 
> Cheers,
> Biff



Sorry Biff, I wasn't able to get a reliable range for either.

Someone else help?


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## Shortround6 (Oct 16, 2018)

The P-39 was a slick aircraft (low drag) but it was heavy. It did do pretty well in miles per gallon but a lot of these aircraft were pretty close together and does a 10-20% change in range really amount to all that much operationally?

Like if plane "A" has a operational radius if 100 miles and plane "B" has an operational radius of 120 miles and you are dealing with the English channel which can be 100 miles wide (or more) in some spots what is the practical difference?
Even on the Eastern front, sometimes a battle will be that grey zone where plane B can reach it from a certain airfield but plane A can't but how often is that going to happen where there isn't one or more airfields closer to the battle that Plane A couldn't stage through, either going or coming. 


Here is the range chart for a P-39Q-1.
http://zenoswarbirdvideos.com/Images/P-39/P39FOIC.pdf

down low (0-6000ft) at 250-260mph it can do about 260 miles after subtracting 6-17 gallons for warm up and take off. WIth 120 gallon tanks (105 usable) it should do about 390 miles at that speed but there is no allowance for either combat or for finding home base and landing. Slower speeds give more range and max continuous less.

In British terms the P-39Q comes out like this for 5 minute fuel usage. 

Cruise condition..................5 min at Military power...........5 min at WEP
Max cruise 3.125mpg.................36 miles................................44 miles
Intermed (2nd column)...............44 miles................................53 miles
most economical........................74 miles................................90 miles

Fractions rounded off. 

Spitfires were all over the place in regards to fuel capacity. with 102 US gallons on the early ones. 146 US gallons on the MK VII & VIII, 114 US gallons on some late MK IXs

And then you have the fact that the Spitfire _could _operate with the 36 gallon Slipper tank (perform all combat maneuvers?) , how often this was done I don't know. 
Apparently it was only the Griffon engined MK XIV that used the 108 US gallon slipper tank in combat? 
Unknown to me is if the 54 US gallon slipper tank was ever used in combat. 

By used in combat I mean the plane did not drop it when engaging the enemy. I have no idea if there were fuel feed problems with any of theses slipper tanks or if there was a problem with fuel sloshing around if the tank was part full. (how much internal baffling there was? Or how strong the attachment points were. 

My Apologies to our commonwealth members but I figured I would keep all fuel in US gallons to help eliminate confusion.

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## Milosh (Oct 16, 2018)

The Pilot manual for the Fw190A-8 has range data.
Pilot manual flugzeug handbuch focke wulf fw 190a 8 english ocr


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## tomo pauk (Oct 16, 2018)

BiffF15 said:


> Ranges for each? I’m curious as I’ve always looked at the Fw190 and Me109 as very short ranged or point defense fighters and if the P39 is similar it changes how I have historically perceived it.
> 
> Cheers,
> Biff



The contemporary (1945?) data shows the 109G making 615 miles on internal fuel (88 imp gals), and 1000 miles with the usual 66 imp gal drop tank: table
For flying under unspecified conditions.*
That is quite a good result, a tad better than the Spitfire with 2-stage Merlin aboard and 85+90 imp gals. Please note that a Tempest V with 188 imp gals of internal fuel will make 850 miles (and 1770 with 2x90 gal tanks), unfortunately that improvement came about too late, well in second half of 1944. Also note the useful increase in range when Spitfires are outfitted with rear fuel tanks.

*seems like most economical speed: picture

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## BiffF15 (Oct 16, 2018)

Gents,

If I read correctly then the 109 and 39 had very similar ranges. SR6 I looked at your chart and found a max range of just over 400 miles but could not read any of the notes. Regardless I’m assuming both were fairly short legged by US standards when compared to P38s and P40s, which would have been their contemporaries (?). For some reason I thought the P39 had better legs than that.

Thanks for the info gents!

Cheers,
Biff


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## Mike Williams (Oct 16, 2018)

Shortround6 said:


> Apparently it was only the Griffon engined MK XIV that used the 108 US gallon slipper tank in combat?
> Unknown to me is if the 54 US gallon slipper tank was ever used in combat.


As previously posted in the P-38 thread, Spitfire IX combat with 90 gallon drop tank attached:
http://www.wwiiaircraftperformance.org/126-Rae-14aug44.jpg

Spitfire XIV combat with 45 gallon drop tank attached:
http://www.wwiiaircraftperformance.org/41-coleman-20april45.jpg

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## Mike Williams (Oct 16, 2018)



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## eagledad (Oct 16, 2018)

Wuzak,

You are correct, I did mis-understand what you had written. However, in the process I learned something new about the Spitfire Mk IX!

Thanks!

Eagledad


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## Denniss (Oct 16, 2018)

A 5/43 range report probably of a british-captured Bf 109G-2 trop:


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## P-39 Expert (Oct 20, 2018)

Ivan1GFP said:


> Hello P-39 Expert,
> What you are stating isn't really accurate.
> The FW 190A through the A-7 and even early A-8 series had two fuel tanks as standard.
> The Forward Tank was 233 Liters (61,5 USG)
> ...


P-39 held more internal fuel than FW190 RELATIVE TO THE DISPLACEMENT/OUTPUT of the engine.

Two planes each hold 150gal, one has a 2000hp engine and one has a 1000hp engine. The 1000hp plane holds more fuel.


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## P-39 Expert (Oct 20, 2018)

BiffF15 said:


> You guys are much sharper than I on these two aircraft. My question is how did they stack up or compare range wise. I’m assuming the radial had a higher gallon per mile covered or greater fuel burn than the inline (V12) of the P39?
> 
> Cheers,
> Biff


The FW190 (clean) endurance was about 1.4hr at high cruise and 2.1hr at low cruise after reserves.

P-39 (clean 120 gal) per manual endurance was about 1.3hr at high cruise and 2.6hr at low cruise at 20k' after reserves (16gal).


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## Ivan1GFP (Oct 20, 2018)

P-39 Expert said:


> P-39 held more internal fuel than FW190 RELATIVE TO THE DISPLACEMENT/OUTPUT of the engine.
> 
> Two planes each hold 150gal, one has a 2000hp engine and one has a 1000hp engine. The 1000hp plane holds more fuel.



Hello P-39 Expert,
I believe you are using a rather contrived measurement that is pretty meaningless.

If you want to play with the numbers, then you should look at the early FW 190A that only had about 1450 HP and a late model Airacobra that had about the same amount of power.
How about a comparison between the Daimler Benz DB 605 versus the Merlin or the Allison V-1710?
The power outputs were fairly similar but the DB605 has a lot less supercharger and a lot more displacement.

Here's a good question: When the comparing the FW 190A to the FW 190D, which had more fuel?
The actual fuel volumes are identical, but the inline has more power even though it has less displacement.

This is why I believe your assertion does not hold up well.

- Ivan.

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## Milosh (Oct 20, 2018)

P-39 Expert said:


> The FW190 (clean) endurance was about 1.4hr at high cruise and 2.1hr at low cruise after reserves.
> 
> P-39 (clean 120 gal) per manual endurance was about 1.3hr at high cruise and 2.6hr at low cruise at 20k' after reserves (16gal).



Depends on what altitude. 
Fw190A-8
1.2hr @ 0.3km @ 2300rpm @ 1.2ata @ 515kph
2.1hr @ 0.3km @ 2000rpm @1.05ata @ 440kph

1.48hr @ 7.0km @ 2300rpm @ 1.2ata @ 580kph
2.18hr @7.0km @ 2000rpm @ 1.05ata @ 495kph


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## Ivan1GFP (Oct 20, 2018)

Milosh said:


> Depends on what altitude.
> Fw190A-8
> 1.2hr @ 0.3km @ 2300rpm @ 1.2ata @ 515kph
> 2.1hr @ 0.3km @ 2000rpm @1.05ata @ 440kph
> ...



I wonder how much this changes when each is carrying maximum external tanks.
I believe the P-39 could carry at most one external tank and the FW 190 could carry three.

- Ivan.


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## Milosh (Oct 20, 2018)

with 300litre drop tank
3.24hr @ 0.3km @ 2000rpm @ 1.05ata @ 415kph
3.1hr @ 5.0km @ 2000rpm @ 1.05ata @ 485kph


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## Ivan1GFP (Oct 21, 2018)

Milosh said:


> with 300litre drop tank
> 3.24hr @ 0.3km @ 2000rpm @ 1.05ata @ 415kph
> 3.1hr @ 5.0km @ 2000rpm @ 1.05ata @ 485kph



I wonder how far it would go with either two or three drop tanks.
This critter is carrying 2 x 300 liter tanks but the center position could also carry a tank instead of the 250 Kg bomb that is here.


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## Denniss (Oct 21, 2018)

3 d/t was unlikely unless they had some extra oil reservoir installed somewhere


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## P-39 Expert (Oct 21, 2018)

Ivan1GFP said:


> I wonder how much this changes when each is carrying maximum external tanks.
> I believe the P-39 could carry at most one external tank and the FW 190 could carry three.
> 
> - Ivan.


P-39 could carry various tanks up to 175gal (660litres) on its center line giving 6.7hr at low cruise of 41gph and 3.3hr at high cruise of 82gph at 20000'. At high cruise at 25000' it was good for 4.4hr. After reserve for takeoff.


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## fubar57 (Oct 21, 2018)

Documentation.....?


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## P-39 Expert (Oct 21, 2018)

Ivan1GFP said:


> Hello P-39 Expert,
> I believe you are using a rather contrived measurement that is pretty meaningless.
> 
> If you want to play with the numbers, then you should look at the early FW 190A that only had about 1450 HP and a late model Airacobra that had about the same amount of power.
> ...


How else can you compare fuel load on different aircraft with vastly different engines? Why would you compare an early FW190 (1941) with a late model P-39 (mid '44) when one has 2600CID and one has 1710? One has 1700HP and one has 1150/1325/1200hp depending on model?


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## Shortround6 (Oct 21, 2018)

Simply compare actual range/radius at a given speed/altitude. And then ignore anything much under a 20% difference (arbitrary) as useful for winning bar bets but pretty much useless for figuring out operational differences. 

Using ferry tanks makes for a mildly interesting number but is useless for figuring out operational capabilities. Hurricanes could carry a pair of 44 imp gallon drop tanks for combat but could carry a pair of 90 imp gallon tanks for ferrying. Trying to use them means you can get a Hurricane much deeper into enemy territory than it can get out if drops the tanks with fuel in them. 

Comparing peak or max HP is also a rather false assumption to compare fuel capacity to. as most of the time such power/fuel consumption was only used for a small percentage of the flight.


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## Reluctant Poster (Oct 21, 2018)

wuzak said:


> Was looking for a Spitfire IX data sheet and found this - fuselage tank mods for a long range IX
> http://www.spitfireperformance.com/spitfire9-fuelsystem-lr.jpg
> 
> I think the date is 1945, but I can't tell for sure.
> ...


The Mark XIV reverted to 85 imp gallons forward of the pilot. This was due to the relocation of the oil tank from under the engine to in front of the pilot.
According to Spitfire by Morgan and Shacklady, late model Mark IXs had two 18 imp gallon Mareng bags in the wings.


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## wuzak (Oct 21, 2018)

Reluctant Poster said:


> The Mark XIV reverted to 85 imp gallons forward of the pilot. This was due to the relocation of the oil tank from under the engine to in front of the pilot.
> According to Spitfire by Morgan and Shacklady, late model Mark IXs had two 18 imp gallon Mareng bags in the wings.



Thanks RP.


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## tomo pauk (Oct 21, 2018)

P-39 Expert said:


> How else can you compare fuel load on different aircraft with vastly different engines? Why would you compare an early FW190 (1941) with a late model P-39 (mid '44) when one has 2600CID and one has 1710? One has 1700HP and one has 1150/1325/1200hp depending on model?



I really wonder when people will stop posting bogus figures on this fine forum.
Fw 190 from 1941 have had 1600 HP engine, that power being limited to 3 minutes. P-39 from mid-1944 have had 1420 HP (5 min limit). Talking about cubic inches is meaningless, it is thrust (enabled by power + prop combination, plus exhaust thrust) what propells aircraft, not cubic inches.

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## Ivan1GFP (Oct 21, 2018)

Denniss said:


> 3 d/t was unlikely unless they had some extra oil reservoir installed somewhere



Very good point!



P-39 Expert said:


> How else can you compare fuel load on different aircraft with vastly different engines? Why would you compare an early FW190 (1941) with a late model P-39 (mid '44) when one has 2600CID and one has 1710? One has 1700HP and one has 1150/1325/1200hp depending on model?



Just use the actual volumes. That is pretty hard to dispute.

If you really want to play with some numbers, how about comparing a fairly early (1942) P-39D-2 or P-39K with a V-1710-63 engine?
At low altitude, those engines were putting out well over 1500 HP on War Emergency power which isn't that different from a contemporary FW 190A....

When you start comparing engine designs, there are a lot more characteristics that affect things than simple displacement and power output.
Factor in manifold pressure and RPM and things even out a bit but of course there are consequences to those choices.

- Ivan.


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## Kevin J (Oct 21, 2018)

Ivan1GFP said:


> Very good point!
> 
> 
> 
> ...


I thought war emergency only became available on the P-39K or did the Russians get there earlier on the D-2?


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## Greyman (Oct 21, 2018)

With no automatic boost control - are manifold pressures limited (to a certain extent) only by the throttle discipline of the pilot?


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## Shortround6 (Oct 21, 2018)

Greyman said:


> With no automatic boost control - are manifold pressures limited (to a certain extent) only by the throttle discipline of the pilot?


 Even with automatic boost control _most _planes were limited timewise by the "throttle discipline of the pilot". 
I believe that only the Germans put clockwork timers on the boost control that automatically returned the boost control to "normal" after a set period of time. Open to correction. 
Most countries used some form of boost limiting (max boost the pilot could not exceed by throttle movement alone) _except_ the United States but while it gave more flexibility it added greatly the workload. A Longnose P-40 could pick up 8in (4lbs) of boost dropping from 12,000ft to 6,000ft if he didn't throttle back.

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## Greyman (Oct 21, 2018)

That's what I was getting at re: Kevin J's post. Bell/Curtiss/Allison can tell the pilots that the maximum permissible boost is 42 inches all it wants - if the pilot says "Nope, it's 56 inches" then that's that. I've read many times that the Russians never took the American engine limitations seriously.

_Main difference in the assessment of P-40's combat capabilities comes from that we and Allies had completely different exploitation of the aircraft. They use it as written in manuals, from letter to letter. We, as I said before, had a main rule is to take from the machine everything possible. How much "everything" is, it did not write in manuals, and even airplane designer didn't anticipate. This appears in combat. Everything said above goes for Airacobra, too. Have we flown them how Americans wrote it in the manual, we would all got shot down. It was a dud as the fighter aircraft on "birth" regime. On our regimes we had a equal combat with either MEs or FWs, but it would have meant 3-4 combats with subsequent engine change._
__-- General-Major Nikolay Gerasimovich Golodnikov

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## Ivan1GFP (Oct 21, 2018)

Kevin J said:


> I thought war emergency only became available on the P-39K or did the Russians get there earlier on the D-2?



Hello Kevin J,
The story of the P-39 is a very strange one for designations.
Very minor equipment changes were sufficient for a letter designation change.
The P-39D-2 and P-39K were contemporaries (mid 1942) and both used the same V-1710-63 engine.
The only real differences were some armour arrangements, the switch from a Curtiss Electric to a Aeroproducts Propeller and a possible change in cannon armament (depending on what source of documentation you wish to believe).
Another example is the P-39F which immediately followed P-39D production and was identical but for a different propeller as for D-2 to K.
Even the earlier P-39D, D-1, and F with the V-1710-35 engine had a War Emergency rating (51.0 inches Hg).
This was mentioned in the tests of the Airacobra against Koga's captured A6M2.

Attached is a letter from Allison regarding overboosting these early engines.
As I see it, but for the reduction gear arrangement, the V-1710-35 and -39 are close equivalents as are the -63 and -73.
Later engines were much less tolerant of high boost pressures.

- Ivan.

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## Kevin J (Oct 21, 2018)

Ivan1GFP said:


> Hello Kevin J,
> The story of the P-39 is a very strange one for designations.
> Very minor equipment changes were sufficient for a letter designation change.
> The P-39D-2 and P-39K were contemporaries (mid 1942) and both used the same V-1710-63 engine.
> ...


Yes, seen that, but I thought the early Cobra engines were more like those of the Tomahawks and without the WEP option.


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## Ivan1GFP (Oct 21, 2018)

Kevin J said:


> Yes, seen that, but I thought the early Cobra engines were more like those of the Tomahawks and without the WEP option.



The point I was making was that these early Airacobra engines were more closely equivalent to the P-40D/E/K types.
The problem is that different sources don't all agree as to what the limitations were.

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## Shortround6 (Oct 21, 2018)

There was a change in the engines around Dec of 1941. They switched from using a shot peened crankshaft to one that was nitrided and shot peened with much greater fatigue life.
Somewhere over the winter of 1941/42 they also changed the casting method for the crankcase and cylinder blocks. There doesn't seem to be any change in engine designation for these changes and the new crankshaft could be put in an old engine. This is part of the reason that the engines in the D-2 and K s were rated at 1325hp for take-off.
For the earlier Ds limitations are going to be kind of up to the users. The USAAF didn't officially approve WEP ratings until the late fall of 1942 which is well after most of the early Ds had left the production line. There may have been twice as many (or more) planes with the new, tougher engines than with the old engines.

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## Ivan1GFP (Oct 21, 2018)

Shortround6 said:


> There was a change in the engines around Dec of 1941. They switched from using a shot peened crankshaft to one that was nitrided and shot peened with much greater fatigue life.
> Somewhere over the winter of 1941/42 they also changed the casting method for the crankcase and cylinder blocks. There doesn't seem to be any change in engine designation for these changes and the new crankshaft could be put in an old engine. This is part of the reason that the engines in the D-2 and K s were rated at 1325hp for take-off.
> For the earlier Ds limitations are going to be kind of up to the users. The USAAF didn't officially approve WEP ratings until the late fall of 1942 which is well after most of the early Ds had left the production line. There may have been twice as many (or more) planes with the new, tougher engines than with the old engines.



The Take-Off rating of the V-1710-63 engines was 1325 HP, but there was a War Emergency rating that isn't in the SEFC, so I need to figure out where I saw this originally. 
America's Hundred Thousand lists this as
1590 HP @ 3000 RPM @ 2500 feet at 61.0 inches Hg.

The fall of 1942 would match up pretty well with the various tests against Koga's A6M2 which began test flights in September, so if a WEP rating was approved by then, it would make sense the Airacobra in the test would be using it.



fubar57 said:


> Documentation.....?



Regarding the 175 Gallon drop tank, AHT also shows a range graph of the P-39 carrying as much as 295 Gallons of fuel with a note that all fuel above 120 Gallons was carried in a Center Line Drop Tank.

- Ivan.


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## P-39 Expert (Oct 22, 2018)

tomo pauk said:


> I really wonder when people will stop posting bogus figures on this fine forum.
> Fw 190 from 1941 have had 1600 HP engine, that power being limited to 3 minutes. P-39 from mid-1944 have had 1420 HP (5 min limit). Talking about cubic inches is meaningless, it is thrust (enabled by power + prop combination, plus exhaust thrust) what propells aircraft, not cubic inches.


Aint no replacement for displacement. The bigger the engine the more gallons per hour it burns. Hard to compare fuel loads for a plane that burns 200gph vs one that burns 100gph.

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## tomo pauk (Oct 22, 2018)

P-39 Expert said:


> Aint no replacement for displacement. The bigger the engine the more gallons per hour it burns. Hard to compare fuel loads for a plane that burns 200gph vs one that burns 100gph.



34 liters: DB 601E: 1200 PS at 4.9 km, 98.3 gph, 1350 PS at SL, 117.5 gph
27 liters: V-1650-1: 1240 HP at 11500 ft, 123 gph; 1120 HP at 18500 ft, 120 gph: 1300 HP at SL, 133gph
27 liters: V-1710-85: 1125 HP at 15500 ft, 138 gph; 1420 HP at 9000 ft, 170 gph.

Say again?

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## parsifal (Oct 22, 2018)

yet more unsubstantiated argument. I cant say much about planes, but for cars, the fastest and most powerful engines are not the largest.

For the time being, the Koenigsberg Agera RS is the most powerful production engine available (for cars). At 5.0 litres capacity the engine is large, but by no means the largest. It has a biturbo 5.0-liter unit that has 1,360 hp (1,014 kWThe fastest, soon to be boosted to over 1700 hp.


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## Shortround6 (Oct 22, 2018)

Fuel burn is going to proportional to the power being made, everything else being equal (which it won't be).
The larger engine could be expected to burn more fuel if it is turning the same RPM as the smaller engine and making more power. The V-1710 and the V-1650 were two of the few engines that turned at 3000 rpm. Most of the German V-12s turned at 2600-2800rpm (except for the older engines and the Jumo 213) and most radials ran at around 2700 rpm. There are exceptions. Then you get to the amount of boost used. Germans used low boost so they had a lower percentage of air going through the engine per rpm/.
The Allison in a P-39Q was using about 1.49 ata for military power, 1.69 ata for take-off and 1.9 ata for WEP. 
Once you get to radial engine planes like the FW 190 the drag of the engine installation was a lot closer to the drag of a V-12 so the power (and fuel burn) needed at cruising speeds wasn't that far off, perhaps around 10%. Older radials were pretty bad. At high power the radials may have shifted to rich mixture sooner or used an even richer mixture than the V-12s at full power but then that level of power is only used for 15-20 minutes of a 1-2 hour flight (or longer).


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## Ivan1GFP (Oct 22, 2018)

parsifal said:


> yet more unsubstantiated argument. I cant say much about planes, but for cars, the fastest and most powerful engines are not the largest.
> 
> For the time being, the Koenigsberg Agera RS is the most powerful production engine available (for cars). At 5.0 litres capacity the engine is large, but by no means the largest. It has a biturbo 5.0-liter unit that has 1,360 hp (1,014 kWThe fastest, soon to be boosted to over 1700 hp.



That is KoenigSEGG Agera.
I am actually in pretty good agreement with your general idea, but the problem with an analogy of street-able and production cars is that they must all fit on the existing roads. There isn't the same issue with getting an aeroplane in the air. The sky is a pretty big place. If you are looking for the absolute fastest piston powered cars, then you might consider the ones that have been run at Bonneville. Those DO tend to have very large displacement engines but are certainly not production street cars.
I also thought about bringing up comparisons of auto engines that I have some personal experience with, but this is already getting way off topic. 

- Ivan.

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## wuzak (Oct 22, 2018)

Ivan1GFP said:


> If you are looking for the absolute fastest piston powered cars, then you might consider the ones that have been run at Bonneville. Those DO tend to have very large displacement engines but are certainly not production street cars.



And often more than one.

The land speed record for a piston powered car is 439mph. For a turbine wheel riven car it is 458mph.

https://www.fia.com/file/51532/download?token=KPX0lkyA


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## Ivan1GFP (Oct 22, 2018)

Hopefully we can get back to the original topic of the Airacobra versus German (or other contemporary) fighters.

Here is how I would characterize the Airacobra:
It was a very slick aircraft aerodynamically at least for profile drag.
There were no protruding radiators though it did have a small belly bump.
Its choice of airfoil probably hurt its maneuverability to some extent.
(Root: NACA 0015, Tip: NACA 23009)
The symmetrical airfoil tends to have a lower than typical Coefficient of Lift (about 1.3) but the NACA 23000 series airfoil at the tip is a bit higher lift and one of the more common airfoils used in fighters of this era.
NACA Report L-602 - Flying Qualities of P-39D-1 states that max CL is about 1.4.
This is in contrast to the stall speeds listed in Operating Manual for P-39Q-1:
(105 MPH Clean, 90 MPH Flaps Down)
With a stall speed of 105 MPH, even at a weight of 7800 pounds which is about what it would weigh with full fuel and ammunition but no external stores, the calculated CL is only about 1.30.
Perhaps there are a couple MPH in rounding errors?

As Shortround6 pointed out in another thread, the Mid-engine arrangement cost some extra weight in the Airacobra because of additional strength needed between the engine and propeller. There was probably a bit more than that for the separate oil reservoir and pumps needed for the remote reduction gear behind the propeller.
The Tricycle gear made for great ground handling and visibility and easy take-offs and landings, but also cost some extra weight about what a smaller tail wheel might have cost.

The hidden radiators and oil coolers were good from a drag standpoint but not so good from a cooling standpoint.
The Airacobra would tend to overheat in prolonged ground running or in hot climates.
In flight tests, it also had a tendency to overheat.

In the air, there was the CoG movement issue which actually seemed to be more a result of firing off the ammunition for the .50 Cal Cowl Guns than the Cannon ammunition. This has already been discussed at length.
Apparently it was possible to make the Airacobra "Tumble" by flying vertically until airspeed dropped to zero and with proper control inputs, but it was a fairly violent maneuver even if it was planned (from Pilot accounts found in Crowood book about P-39).

Other handling characteristics were a very sensitive Elevator (from NACA L-602) and a rather mediocre roll rate which was about 85 degrees / second max. Perhaps the Russians were able to increase this a bit by deleting the wing guns.

Stall characteristics were very good with a tendency to mush at the stall and the wing tips stalled last for good lateral control.

Speed of a late model Airacobra (P-39Q) was quite good. With the Wing Gun Pods removed, it was probably very close to a 400 MPH aircraft.

Thoughts?
- Ivan.

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## XBe02Drvr (Oct 22, 2018)

Ivan1GFP said:


> Apparently it was possible to make the Airacobra "Tumble" by flying vertically until airspeed dropped to zero and with proper control inputs, but it was a fairly violent maneuver even if it was planned


DUHH! That's a tail slide, which looks and feels like a tumble and is a violent maneuver in ANY airplane, though not a true tumble as in a Lomcevak or a roll divergence departure in an F4-A4-F101-F104 class jet. Not a good idea in any civil airplane except an all-out acro machine.
Cheers,
Wes


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## Ivan1GFP (Oct 22, 2018)

XBe02Drvr said:


> DUHH! That's a tail slide, which looks and feels like a tumble and is a violent maneuver in ANY airplane, though not a true tumble as in a Lomcevak or a roll divergence departure in an F4-A4-F101-F104 class jet. Not a good idea in any civil airplane except an all-out acro machine.
> Cheers,
> Wes



Hello XBe02Drvr,

Eeek! Jets again!

I KNOW what a Tailslide is and I know what a Hammerhead is. That is why I described it the way I did with the specific conditions that it took to actually make an Airacobra tumble.
Keep in mind that we are discussing an aeroplane that is fairly small for a fighter but very heavy in comparison to the aerobatic types we see today.
Combine that with a CoG that is far enough aft to make the aeroplane unstable and apparently the critter can be made to tumble.
One thing I remember is that the pilot was very specific about bracing the control stick or it would thrash about quite violently.
Such are the pilot accounts in the Crowood book. I can find the reference if you need but it may take a while.
Remember, this was not a civil aeroplane and I strongly doubt this maneuver was ever approved.

Keep in mind also that ANY aeroplane can fly a Tailslide, but the Airacobra was rather unique in its reputation (deserved or not) for tumbling.

- Ivan.


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## XBe02Drvr (Oct 22, 2018)

Ivan1GFP said:


> I KNOW what a Tailslide is and I know what a Hammerhead is. That is why I described it the way I did with the specific conditions that it took to actually make an Airacobra tumble.


I've ridden (not flown) through tail slides in the Pitts and the T-34; you can make them swap ends (violently!) either forwards or backwards depending on which way you brace the stick. But still they swap ends suddenly followed by a couple of oscillations as they accelerate downward, not entering a sustained end-over-end tumble as the(eeek!) jets do. There's a NAVAER training video circa 1967 on roll divergence that shows F4s and A4s doing divergence departures. Pretty amazing to see smoke streaming out of the intake ducts. If you have a reference for a sustained Cobra tumble, that would be interesting to see. Thanks.
Wes


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## fliger747 (Oct 23, 2018)

I'm glad the Russians liked the plane, developed good tactics and found it effective. As far as over boosting and detonation, thins will have a lot to do with the ambient temperature. In Russia in the "cooler" season considerably more power could be developed than on a standard day. Engines in their design have some characteristics that allow more leeway than others. The R2800 (an engine that I Am familiar with was structurallyquite tolerant of high MP values but not at all tolerant of over RPM. The improvements going to the C models from the B models were many, but an extra 100 max RPM was achieved. Importantly the oil scavenge system was improved as several hundred HP were utilized in slinging oil around in the crankcase. 

Not often appreciated was the power required to run the supercharger. For the R2800 with a 2 stage blower, high blower operation could subtract as much as 400 HP!

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## P-39 Expert (Oct 23, 2018)

P-39 vs German fighters, here you go:

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## Ivan1GFP (Oct 23, 2018)

XBe02Drvr said:


> I've ridden (not flown) through tail slides in the Pitts and the T-34; you can make them swap ends (violently!) either forwards or backwards depending on which way you brace the stick. But still they swap ends suddenly followed by a couple of oscillations as they accelerate downward, not entering a sustained end-over-end tumble as the(eeek!) jets do. There's a NAVAER training video circa 1967 on roll divergence that shows F4s and A4s doing divergence departures. Pretty amazing to see smoke streaming out of the intake ducts. If you have a reference for a sustained Cobra tumble, that would be interesting to see. Thanks.
> Wes



Hello XBe02Drvr,
Actually I have ridden through a Tailslide also (in a Cessna 152). We were doing multiple loops with a 90 degree roll between each and didn't have quite enough energy to finish. I think we ended up in one or two rotations of a spin after finishing the first two loops. Things happen in slow motion in a Cessna, so it wasn't bad at all.
I remember the Instructor telling me that you can tell if you have aligned your loop correctly if you feel the bump when flying through your own slipstream at the completion of the loop.

I never claimed it was a "sustained Cobra tumble", just a tumble.

Just to make sure we are on the same page:
I am stating that I was reading a pilot's description of how to make an Airacobra tumble.
This was in the Crowood Aviation Series book "Bell P-39 Airacobra" by Robert Dorr and Jerry Scutts (Page 44).
I believe the account to be plausible; The Airacobra has a reputation for tumbling though attempts to duplicate tend to vary in their accounts. Very few aeroplanes have this reputation.

You, on the other hand, do not believe the Airacobra could tumble. You believe that the pilots were actually experiencing a Tailslide and did not recognize that fact.

Eeek, Jets!
I do agree that roll divergence in its various forms is interesting but am choosing not to get into that discussion at the moment because it is somewhat irrelevant to the current issue.

- Ivan.

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## P-39 Expert (Oct 25, 2018)

Ivan1GFP said:


> Hopefully we can get back to the original topic of the Airacobra versus German (or other contemporary) fighters.
> 
> Here is how I would characterize the Airacobra:
> It was a very slick aircraft aerodynamically at least for profile drag.
> ...


Agree with pretty much everything you said.

The "tumble" could be entered by some and not others after a contrived effort (nose ammo expended, climbing vertically to the stall, etc). A little knowledge could keep you out of a lot of trouble.

It would overheat on the ground if you taxied too long, but for normal operation with this type it wasn't a concern. Forward visibility during taxi was good enough to drive it like a car to the end of the runway, perform your mag and prop checks and take off.

Wouldn't cool to Army hot day cooling requirements during maximum climb but was tolerable for 5 minutes and cooled well at normal operations.


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## Greg Boeser (Oct 25, 2018)

That long nose wheel strut was a bit fragile for rough fields though.


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## P-39 Expert (Oct 26, 2018)

Greg Boeser said:


> That long nose wheel strut was a bit fragile for rough fields though.


Yep, but most all AAF planes needed concrete or steel mat runways. Would like to se some of those fields that they called "rough".


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## fubar57 (Oct 26, 2018)

Airfields had grass runways in England for fighters for the most part


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## P-39 Expert (Oct 26, 2018)

fubar57 said:


> Airfields had grass runways in England for fighters for the most part


Which were probably a lot smoother than those at Port Moresby.

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## Shortround6 (Oct 26, 2018)

A lot of the British (and Continental) prewar grass fields were actually carefully prepared with attentioned paid to drainage, filling in low spots and rolling the field periodically. 
If you can find it the 1938 "Jane's all the World's Aircraft" has a section on airfields/aerodromes with a number of pictures. I mention this edition as it was reprinted by Arco in 70s(?) and may be easier to find than an original. 

Some airfield were actual circular for the flying surface with hangers and terminal/tower on one side, paved aprons in heavy traffic areas with grass flying surfaces.

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## fubar57 (Oct 26, 2018)

I do have that book


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## XBe02Drvr (Oct 26, 2018)

P-39 Expert said:


> Which were probably a lot smoother than those at Port Moresby.


What about those USSR fields? Betcha the Ivans did a lot of taxiing and TO/Ldg with the stick right back in their laps. They still thought it was one of the best fighters they had.
Cheers,
Wes


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## Shortround6 (Oct 26, 2018)

AS to the airfield*S* at Port Moresby :

Port Moresby Airfield Complex - Wikipedia.

Please note that the Americans had used 7 mile Drome to stage through when they ferried B-17s to the Philippines in Sept of 1941. 
The article is not clear as to exactly when the air strips got PSP (like what month) but from the descriptions the Port Moresby air strips were not crude or significantly lacking in engineering support.


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## Milosh (Oct 26, 2018)

Berry Airfield (12 Mile Drome)

The airfield was constructed in early 1942, being completed on 15 May. The airfield had an 8-inch base of crushed rock and pit gravel for a single earth runway approximately 4,500' by 150.

40th and 80th FS USAAF with P-39s stationed there.

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## Ivan1GFP (Oct 26, 2018)

XBe02Drvr said:


> What about those USSR fields? Betcha the Ivans did a lot of taxiing and TO/Ldg with the stick right back in their laps. They still thought it was one of the best fighters they had.
> Cheers,
> Wes



Hello XBe02Drvr,

Maybe Ivan thought it was one of their best fighters because other aircraft also had their own issues.

Хотя трехколесное шасси обеспечивало прекрасный обзор на рулении и взлете, и в принципе позволяло перемещаться по аэродрому с большой скоростью, не опасаясь капотирования, на неровных грунтовых аэродромах носовая стойка вибрировала и нередко ломалась, что вынуждало ограничивать скорость руления.

Although the three-wheeled chassis provided excellent visibility on taxiing and take-off, and in principle allowed to move around the airfield at high speed without fear of nosing, on uneven ground airfields the nose strut vibrated and often broke, which made it necessary to limit the taxi speed.

from:
Недостатки P-39 Аэрокобра

- Ivan.


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## CORSNING (Oct 26, 2018)

Ivan1GFP said:


> America's Hundred Thousand lists this as
> 1590 HP @ 3000 RPM @ 2500 feet at 61.0 inches Hg.
> 
> Ivan, I have had a long day at work and am too tired to look this up.
> ...


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## CORSNING (Oct 26, 2018)

wuzak said:


> And often more than one.
> 
> The land speed record for a piston powered car is 439mph. For a turbine wheel riven car it is 458mph.
> 
> https://www.fia.com/file/51532/download?token=KPX0lkyA



*Maybe, but check this little bugger out.*

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## Ivan1GFP (Oct 26, 2018)

Hello Corsning,

Look on Page 191 of AHT.
I tried to do a scan of that page but I do not have scanning software on my laptop and GIMP seems to have issues with the scanner which is why the model designations are cropped. The engine variants are still readable, so this should be sufficient.
The original source I found had slightly different information on it.
Manifold Pressure was in the high 50's (maybe 57 or 59 inches Hg) and power was only 1550 HP.

- Ivan.

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## CORSNING (Oct 26, 2018)

Thank you Ivan, I am just a wee bit tired tonight and appreciate the help.
, Jeff


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## Kevin J (Oct 26, 2018)

Ivan1GFP said:


> Hello Corsning,
> 
> Look on Page 191 of AHT.
> I tried to do a scan of that page but I do not have scanning software on my laptop and GIMP seems to have issues with the scanner which is why the model designations are cropped. The engine variants are still readable, so this should be sufficient.
> ...


That's pretty much what I understood from what I've read on the Russian sites. No WEP until the P-39D-2/K. So no more power than the Tomahawk had and that entered service in 1940.


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## Ivan1GFP (Oct 26, 2018)

Hello Corsning,
No problem!
You caught me at just the right time. I am just packing for a trip.
In a couple hours I won't have access to my laptop or to all the books at home, so with just a cell phone for Internet access, I won't be posting anything for a couple days.

Hello Kevin J,
You presume this is the only reference there is. It most certainly is not.
It just happened to be the easiest place to find what I needed to address one specific point.
As Shortround6 and I were discussing earlier, by late 1942, there was a WEP specification even for the early V-1710-35.
You can see the Allison memo to address what the services were ALREADY doing in the field.
I am stating specifically that WEP was used by the P-39D or D-1 (not D-2, not K) that was tested against Koga's A6M2 starting September 1942.
At least that is what the books say.
One has to wonder why the K was not tested against A6M2 since it begin production in July.

You can of course believe what you will. There is also a Russian manual for the P-39 with the Allison E4 engine (V-1710-35) and I have translated parts of it and found some fairly cool stuff but haven't gone looking for the power settings.

- Ivan.

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## pbehn (Oct 26, 2018)

fubar57 said:


> Airfields had grass runways in England for fighters for the most part


Certainly true at the outbreak of the war, by the end of the war most were hard top, concrete at least. Building runways in UK was a huge civil project in ww2.

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## Kevin J (Oct 26, 2018)

Ivan1GFP said:


> Hello Corsning,
> No problem!
> You caught me at just the right time. I am just packing for a trip.
> In a couple hours I won't have access to my laptop or to all the books at home, so with just a cell phone for Internet access, I won't be posting anything for a couple days.
> ...


My understanding was that WEP was only allowed in the V-1710-39 of the P-40D/E from the beginning,not the V-1710-35/37 of the P-39C/D/D-1.


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## fubar57 (Oct 26, 2018)

pbehn said:


> Certainly true at the outbreak of the war, by the end of the war most were hard top, concrete at least. Building runways in UK was a huge civil project in ww2.


I read that the breakaway from grass was due to heavier bomber introduced though I can't recall the time frame


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## pbehn (Oct 26, 2018)

fubar57 said:


> I read that the breakaway from grass was due to heavier bomber introduced though I can't recall the time frame


Well it pretty much started with the start of the war, ironically assisted by the blitz, the rubble of bombed out cities and towns was used for the hard core. Of course bombers were the heaviest, but fighters were busy gaining weight, the Spitfire doubled in weight while P-47 and Typhoon were the weight of light bombers of a few yrs before. Runways/taxiways and hard standing built in UK were equal to building a highway to China. 
During the years 1939 to 1945, four hundred and forty-four Royal Air Force airfields were constructed in the United Kingdom with paved runways, perimeter tracks, and hard-standings. During the peak construction year of 1942, with a labour force of sixty thousand men, new airfields were being turned out an average rate of one every 3 days in addition to sixty-three major extensions to existing stations (Hudson 1948:5). The whole of the airfield projects were planned administered and supervised by engineering and technical staff operating directly under the Directorate General of Works of the Air Ministry, with the construction work carried out by British contractors. In the early stages of the war programme, the Air Ministry were far sighted enough to select and encourage several major contractors – W&C French, John Laing, Robert McAlpine and George Wimpey. It was on the foundation of these contractors that the airfield construction was based and from which grew a contracting army. Overall in the five years of war, one hundred and thirty six contractors were engaged on a total of eight hundred separate contracts ranging in value from £25,000 (£750,000) to over £3.5m (£105m.) “Six contractors between them, carried out one hundred and ninety-six contracts of major value” (Hudson 1948:44). These projects required large earthmoving operations, on average involving 500,000 cubic yards of earthworks but on special sites up to 3,000,000 cubic yards. By 1942 this vast operation was utilising heavy American plant of the crawler, tractor and scraper type together with British equipment. The paved runways were mainly constructed using concrete paving with or without asphalt or tarmacadam surfacing. In all cases the necessary war-time controls of materials, plant and labour made the site planning and programme of work very much the concern of the Air Ministry. Furthermore, as contractors, particularly smaller firms, were unable to obtain the total plant required for the airfield work by 1944 the Air Ministry had become holders of considerable quantities of construction plant obtained under Lend-Lease or by allocation controlled by a Central inter-Departmental Committee. The Air Ministry holding included, but was not limited to 360 tractors and bulldozers, 250 excavators, 34 scrapers, 406 rollers, 5,300 tipping lorries, 220 dumpers, 150 concrete mixers, 500 power pumps (Hudson 1948:45) from here http://www.arcom.ac.uk/-docs/proceedings/ar2009-0847-0856_Potts.pdf

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## parsifal (Oct 26, 2018)

I don't think Henderson was provided with steel matting until early 1943.

most of the airfields in the northern territory remained dirt strips for nearly the entire war. There a few exceptions 

not all that relevant bu the airfield at RAAF Pearce was sealed from almost the beginning of the war. conversely the training fields at pt cook were unsealed. Amberley was unsealed. Townsville was unsealed until the latter part of 1942

I unsure about Cooktown 

Milne Bay in 1942 was unsealed and had no steel matting until months after the battle


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## Shortround6 (Oct 26, 2018)

Milosh said:


> Berry Airfield (12 Mile Drome)
> 
> The airfield was constructed in early 1942, being completed on 15 May. The airfield had an 8-inch base of crushed rock and pit gravel for a single earth runway approximately 4,500' by 150.
> 
> 40th and 80th FS USAAF with P-39s stationed there.



Apparently there were 7 or 8 airdromes eventually built in the Port Moresby area, I say airdromes because several of them had more than in runway. 

_3 mile_ was the first being built in 1933 although expanded considerably later. It wa operating A-24s in March of 1942 and P-39s in May (30th?).
_7 mile_ was operating P-39s in June of 1942. This was another prewar field enlarged during 1942, it is the one used by the B-17s in 1941, it was used by the RAAF squadron 75 in March of 1942 but was used mostly by bombers.
_12 mile_ was covered by Milosh.
_14 mile_ went into service in Sept 1942 as did _17 mile_. 14 mile operated mainly fighters with a few B-25s and 17 mile operated mainly B-25s with a few fighters. 
_30 mile_ went into service July of 1942 but it's intended PSP planking had been used elsewhere and it was used used as a fighter strip and emergency landing field. At some point it did acquire PSP planking but only 3 US fighter squadrons were ever based there. 
_5 mile_ went into service in Jan 1943. 

Some of these airdromes wound up with interconnecting taxiways.


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## pbehn (Oct 26, 2018)

As soon as the bridgehead was taken and secured after D-Day engineers started constructing matted runways, it may have been possible to operate fully loaded Typhoons from grass, it certainly wasnt the desired option, I cant imagine US forces were any different.


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## Shortround6 (Oct 26, 2018)

In Great Britain the grass (or sod) fields were responsible for the pre-war requirement that tyre pressure no exceed 38lb/sq/in regardless of what type of aircraft. This was to avoid putting runts in the fields. Depth of penetration of the tyres into the field was either 1 or 2 inches (going by memory) and obviously this was inadequate as the plane's weight rose. 

Point is that many of these "grass" airfields bore about as much resemblance to front line airfields as a golf course fairway does to a farmers meadow. And front line airfields could vary tremendously depending on theater and country building the airstrip. 

From Wiki so................"On Pacific islands the matting was typically covered with crushed and rolled coral or soil to form a level surface. The perforated and channeled design of the matting created strength and rigidity and facilitated drainage. A runway two hundred feet wide and 5000 feet (1500 m) long could be created within two days by a small team of engineers." Now this could very well be on an site that was already bulldozed, filled and rolled/compacted.

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## pbehn (Oct 26, 2018)

Shortround6 said:


> In Great Britain the grass (or sod) fields were responsible for the pre-war requirement that tyre pressure no exceed 38lb/sq/in regardless of what type of aircraft. This was to avoid putting runts in the fields. Depth of penetration of the tyres into the field was either 1 or 2 inches (going by memory) and obviously this was inadequate as the plane's weight rose.
> 
> Point is that many of these "grass" airfields bore about as much resemblance to front line airfields as a golf course fairway does to a farmers meadow. And front line airfields could vary tremendously depending on theater and country building the airstrip.
> 
> .


I think in UK peacetime it could be tolerated when an airfield was unfit to fly, once a war is declared that situation cannot be allowed. Any grass airfield that has had constant rain for weeks will just turn to mud. The BoB was famously fought in a glorious summer, that weather doesn't continue all year around.


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## XBe02Drvr (Oct 26, 2018)

Ivan1GFP said:


> on uneven ground airfields the nose strut vibrated and often broke, which made it necessary to limit the taxi speed.


Not alone in that department. Most "nose draggers" had that problem to a greater or lesser extent.
Pre-1975 Cessna 182s were notorious for that, as they had the nose gear strut attached directly to the firewall, a heavy engine, and inadequate elevator authority to keep the nose light while taxying. If you hit a "hollow" while taxying off pavement, you could bottom the strut, bang the prop into the ground, sudden stop the engine, and bend the firewall. An expen$ive mi$take for $ure! Off pavement landings were a no-no. Naturally, this created a boom market for aftermarket STC modifications, most of which were later incorporated into standard production aircraft.
Cheers,
Wes


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## Greg Boeser (Oct 26, 2018)

Aleutian fields were notoriously bad. The field at Adak was built by filling in a tidal lagoon with crushed rock. Flooding was common. Willawaws could peel up the PSP and roll it back like it was paper.


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## XBe02Drvr (Oct 26, 2018)

Shortround6 said:


> This was to avoid putting runts in the fields.


Whasamatter, you don't think undersized piglets make good fill? Cummon, man we gotta work to overcome our prejudices!

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## pbehn (Oct 26, 2018)

XBe02Drvr said:


> Whasamatter, you don't think undersized piglets make good fill? Cummon, man we gotta work to overcome our prejudices!


I suspected a baconist comment but wasn't sure, anyway, I am now in a safe space, so all is OK.


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## Shortround6 (Oct 26, 2018)

I barely passed typing in high school and that was 50 years ago, haven't gotten any better.

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## XBe02Drvr (Oct 26, 2018)

Shortround6 said:


> I barely passed typing in high school and that was 50 years ago, haven't gotten any better.


I never even had typing in high school and I haven't gotten any better, either.
Cheers,
Wes


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## Ivan1GFP (Oct 28, 2018)

XBe02Drvr said:


> Not alone in that department. Most "nose draggers" had that problem to a greater or lesser extent.
> Pre-1975 Cessna 182s were notorious for that, as they had the nose gear strut attached directly to the firewall, a heavy engine, and inadequate elevator authority to keep the nose light while taxying. If you hit a "hollow" while taxying off pavement, you could bottom the strut, bang the prop into the ground, sudden stop the engine, and bend the firewall. An expen$ive mi$take for $ure! Off pavement landings were a no-no. Naturally, this created a boom market for aftermarket STC modifications, most of which were later incorporated into standard production aircraft.



Hello XBe02Drvr,
Perhaps it is a similar problem you are describing and perhaps it is not.
Note that your description was for a prop strike and bending the STRUCTURE to which the nose gear was attached.
This is clearly not the case here, because the description is for breaking the strut rather than the structure to which it was attached.
Note also that the Airacobra actually had enough elevator authority to raise the nose wheel at 50 MPH (from NACA L-602).

I don't really keep track of these kinds of failures but the only other aircraft that I have heard that tended to break the nose gear was the B-26 Marauder. There is mention of excessive (unsafe) vibration of the nose gear on the B-25 Mitchell if the damper was not functional, but not a pattern of breakage. There is also no mention of this as a problem on the P-38 Lightning either.
Without the damper, the Mitchell apparently would vibrate badly enough to pop loose the rivets in the nose structure.

- Ivan.


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## XBe02Drvr (Oct 28, 2018)

Ivan1GFP said:


> Perhaps it is a similar problem you are describing and perhaps it is not.
> Note that your description was for a prop strike and bending the STRUCTURE to which the nose gear was attached.
> This is clearly not the case here, because the description is for breaking the strut rather than the structure to which it was attached.
> Note also that the Airacobra actually had enough elevator authority to raise the nose wheel at 50 MPH (from NACA L-602).


Whether it breaks the strut or the firewall is immaterial from an operational perspective. Sure it matters to engineers and mechanics, but the issue here is how to keep it from happening? Pilots are taught to keep the nose "light" when taxying off pavement. Easier to do in some aircraft than others. Frankly, I'm surprised to hear that the Cobra had no elevator authority below 50MPH. You'd think that with its aft CG, it would be easy to "rock back" on the ground with a little propwash over the elevators. So you have to ride the brakes, keep the stick back in your gut, give her a little power, and try not to pick up too much taxi speed while keeping the nosewheel as light as you can, and praying. Must be the Cessna 182's ancestor.
Cheers,
Wes


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## pbehn (Oct 28, 2018)

XBe02Drvr said:


> Whether it breaks the strut or the firewall is immaterial from an operational perspective. Sure it matters to engineers and mechanics, but the issue here is how to keep it from happening? Pilots are taught to keep the nose "light" when taxying off pavement. Easier to do in some aircraft than others. Frankly, I'm surprised to hear that the Cobra had no elevator authority below 50MPH. You'd think that with its aft CG, it would be easy to "rock back" on the ground with a little propwash over the elevators. So you have to ride the brakes, keep the stick back in your gut, give her a little power, and try not to pick up too much taxi speed while keeping the nosewheel as light as you can, and praying. Must be the Cessna 182's ancestor.
> Cheers,
> Wes


Is it possible that this was just part of the learning curve with tricycle undercarriage? Later designs built on what was learned.


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## Ivan1GFP (Oct 28, 2018)

XBe02Drvr said:


> Whether it breaks the strut or the firewall is immaterial from an operational perspective. Sure it matters to engineers and mechanics, but the issue here is how to keep it from happening? Pilots are taught to keep the nose "light" when taxying off pavement. Easier to do in some aircraft than others. Frankly, I'm surprised to hear that the Cobra had no elevator authority below 50MPH. You'd think that with its aft CG, it would be easy to "rock back" on the ground with a little propwash over the elevators. So you have to ride the brakes, keep the stick back in your gut, give her a little power, and try not to pick up too much taxi speed while keeping the nosewheel as light as you can, and praying. Must be the Cessna 182's ancestor.



This is getting interesting.
The question of what breaks first is important because with sufficient stress SOMETHING will certainly break.
Greg Boeser stated that the Airacobra had a fragile nose gear strut.
The account from the Russian link makes the same assertion, so I believe this is pretty good support.

You believe that the Airacobra did not have enough elevator authority below 50 MPH.
The NACA engineers seemed to think the elevator authority was quite good if the Airacobra could lift its nose wheel off the ground at only 50 MPH. Remember that its stall speed clean is 105 MPH....
Your statement of fault with a prop strike or the possibility of something else breaking if the aircraft should encounter a dip in the ground sounds like a characteristic of ANY aircraft equipped a nose wheel if it should take a hard enough bump and seems related to the Airacobra only in the fact that it had a nose wheel.

- Ivan.

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## Csch605 (Mar 7, 2019)

Greg Boeser said:


> That long nose wheel strut was a bit fragile for rough fields though.


I though so too but watch John Hustons wartime film on the Aleutians. P39s were literally swimming in water. Henderson field, New Guinea and frozen lakes in Russia. They were tough little birds and no tail dragging.


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## Csch605 (Mar 7, 2019)

Barrett said:


> Sidebar: Just received a review copy of the latest in the Osprey "Duel" series: P-39/400 v. A6M2. Amazingly enough, the Bells broke even at 15-15 in New Guinea though of course they claimed 5-6 times as many.


The Aleutians got the P39 20 kills to one combat loss albeit against Rufes and larger seaplanes mostly

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## Csch605 (Mar 8, 2019)

parsifal said:


> P-39s never even came close to shooting down 15 Zekes over Moresby. Try a maximum of 7, but probably closer to 5,
> 
> Ratios for overall P-39/A6M losses are better. All up losses are around 30 for the Zekes to about 60 for the P-39s, though some sources say many more.
> 
> .


The commanders figured out you flew full speed 500 feet off the ground and strafe the Japanese airfields. The Japanese would have a few Zeros on patrol but usually could only have a minute or two to maneuver to attack. Zeros were faster with airspeed gained in a dive but not in level flight. The P39 could just throttle up and leave the fight. If luck was with the P39s they could bounce Japanese planes on takeoff and blast them. The Japanese did not armour up their planes so a few hits and flames galore.

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## Csch605 (Mar 8, 2019)

Shortround6 said:


> It is interesting but flawed, it doesn't really say how the planes were were used (tactics or combat situation) and relies on the rather dubious method of comparing the scores of the top aces. I am not trying to get into an argument about claiming or over claiming or anything like that.
> 
> The method is dubious because it fails to take into account the number of missions flown by the pilots of each type and number of times each pilot was actually engaged in combat. As an extreme example we have Eric Hartman who (according to wiki) He "flew 1,404 combat missions and participated in aerial combat on 825 separate occasions." to get is 352 victories.
> This article does not tell us how many combat missions the various pilots (of several air forces) flew or how many of those missions resulted in actual combat.
> ...


Hartman shot alot of old aircraft to cut his teeth in the early part of the war. Gaining experience and knowledge. Wonder what he thought of the P39?


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## Csch605 (Mar 8, 2019)

BiffF15 said:


> You guys are much sharper than I on these two aircraft. My question is how did they stack up or compare range wise. I’m assuming the radial had a higher gallon per mile covered or greater fuel burn than the inline (V12) of the P39?
> 
> Cheers,
> Biff


P39 range was awful like the Me109. Fw190 learned that Battle of Britain lesson of not just getting there but time to dogfight and get back.


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## GrauGeist (Mar 8, 2019)

Csch605 said:


> Hartman shot alot of old aircraft to cut his teeth in the early part of the war. Gaining experience and knowledge. Wonder what he thought of the P39?


Between 15 April 1943 and 25 April 1945, Hartmann claimed 81 P-39s.
My guess is he didn't think much about them...

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## Stig1207 (Mar 8, 2019)

Csch605 said:


> Hartman shot alot of old aircraft to cut his teeth in the early part of the war



He completed training in 1942 and was assigned to Jg52 in the autumnl of '42. That is rather mid war, not the 'early part'.

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## P-39 Expert (Mar 8, 2019)

Csch605 said:


> P39 range was awful like the Me109. Fw190 learned that Battle of Britain lesson of not just getting there but time to dogfight and get back.


Not quite as bad as a 109. With a drop tank in NG escort missions were a little over three hours.

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## Dimlee (Mar 8, 2019)

Csch605 said:


> Hartman shot alot of old aircraft to cut his teeth in the early part of the war



1st kill in Nov 1942, 2nd kill Jan 1943. This is debatable, but I'd not call that period of war as the early one. As for old aircraft, he claimed U-2, R-5, I-16 at the beginning of his career. That was probably all.
Data from this table:
Aces of the Luftwaffe - Erich Hartmann

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## Ivan1GFP (Mar 8, 2019)

Slightly off topic:

Does anyone know of a very accurate set of technical drawings for the P-39? 
(Preferably a D or F model but I don't think any of the single seaters were that different)

Thanks.
- Ivan.


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## Shortround6 (Mar 8, 2019)

P-39 Expert said:


> Not quite as bad as a 109. With a drop tank in NG escort missions were a little over three hours.


In Europe with a 75 gallon drop tank it would be around 2 1/2 hours, or less. 
Forget the B-17 escort stuff. Most fighters in Europe cruised at around 300mph when in enemy airspace not the just under or just over 200mph that was often used in the Pacific. 
fuel burn was doubled while miles traveled only went up around 50%.


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## P-39 Expert (Mar 8, 2019)

Shortround6 said:


> In Europe with a 75 gallon drop tank it would be around 2 1/2 hours, or less.
> Forget the B-17 escort stuff. Most fighters in Europe cruised at around 300mph when in enemy airspace not the just under or just over 200mph that was often used in the Pacific.
> fuel burn was doubled while miles traveled only went up around 50%.


These were bomber/transport escort missions per Edwards Park in his book "Angels Twenty". They ran their 110 gallon drop tanks dry at one hour and 40 minutes and often had enough fuel before landing for a "rat race" where the leader took them on a wild ride and the rest of the squadron tried to catch him. At 3 hours and, say, 12 minutes they would have burned about 66gph on 230 gallons less TO allowance of 20 gallons. These were not Pacific missions over water where enemy contact was unlikely, but missions to Wau, Lae etc. that were overland less than 200 miles away and enemy contact would be imminent.

Those guys didn't really consider the transport escort missions as combat, but the AAF gave them medals for completing X combat missions which included those. The transports were sometimes attacked, but usually just the tail end of the mission after most of the escort was already gone and didn't have the fuel to turn back and fight.

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## MiTasol (Mar 8, 2019)

Ivan1GFP said:


> Does anyone know of a very accurate set of technical drawings for the P-39?



Join Classic Aircraft Blueprints, Drawings & Manuals | AirCorps Library and you can get many of the original factory drawings


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## Milosh (Mar 8, 2019)

Not sure if this has been posted before,
http://zenoswarbirdvideos.com/Images/P-39/P39FOIC.pdf


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## P-39 Expert (Mar 8, 2019)

Milosh said:


> Not sure if this has been posted before,
> http://zenoswarbirdvideos.com/Images/P-39/P39FOIC.pdf


Only about a million times.


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## Shortround6 (Mar 8, 2019)

Thank you, there are manuals on this site that give similar but not complete charts. Just first and last columns. 

The P-39 was cursed (many planes would have loved to have been so cursed ) with being the 2nd lowest drag fighter aircraft the US had. What this means in this case it that it suffered disproportionately compared to many other fighters when you hung a drop tank on it. That or the drop tank installation was really crappy.

At 9,000ft the P-39K&L was _supposed_ (according the charts in the manual) at 1600rpm and 28.5in MAP do 194mph true while burning 35gph while carrying a 75 gallon tank.
At 9,000ft the P-39K&L was _supposed _at 1600rpm and 26.0 in MAP do 230mph true while burning 32gph while clean.
At 9,000ft the P-39K&L was _supposed_ at 2600rpm and 37.55in MAP do 285mph true while burning 106gph while carrying a 75 gallon tank.
At 9,000ft the P-39K&L was _supposed _at 2600rpm and 37.5 in MAP do 340mph true while burning 105gph while clean.

I am sure the 109 posted some similar reductions in speed when carrying the drop tank.

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## P-39 Expert (Mar 9, 2019)

Shortround6 said:


> Thank you, there are manuals on this site that give similar but not complete charts. Just first and last columns.
> 
> The P-39 was cursed (many planes would have loved to have been so cursed ) with being the 2nd lowest drag fighter aircraft the US had. What this means in this case it that it suffered disproportionately compared to many other fighters when you hung a drop tank on it. That or the drop tank installation was really crappy.
> 
> ...


Bell developed a fairing that enclosed the attachment fittings and sway braces that supposedly increased speed by 18mph, but I have only seen the fairing in a very few photos, all on training flights.

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## MIflyer (Mar 9, 2019)

I believe that Hartmann said, "The P-39 performed like the 109 down low." But a book by a WWII German test pilot said he was quite unimpressed with the P-39's speed, although I think the example he ferried had the gear stuck partially down.


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## jmcalli2 (Mar 11, 2019)

Csch605 said:


> The commanders figured out you flew full speed 500 feet off the ground and strafe the Japanese airfields. The Japanese would have a few Zeros on patrol but usually could only have a minute or two to maneuver to attack. Zeros were faster with airspeed gained in a dive but not in level flight. The P39 could just throttle up and leave the fight. If luck was with the P39s they could bounce Japanese planes on takeoff and blast them. The Japanese did not armour up their planes so a few hits and flames galore.



In "P-39/P-400 Airacobra vs A6M2/3 Zero-Sen" author Michael John Claringbould calls the combat losses about equal for the two. In "Twelve to One V Fighter Command Aces of the Pacific War" one of the pilots writes he was sorry to see the P-39Ns go for P-47s, because the N model Airacobra would out climb the Japanese fighters.

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## jmcalli2 (Mar 11, 2019)

Kevin J said:


> Yes, seen that, but I thought the early Cobra engines were more like those of the Tomahawks and without the WEP option.



From WWII Aircraft Performance P-40 and P-39 performance figures a few days apart at the same airfield.


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## P-39 Expert (Mar 11, 2019)

jmcalli2 said:


> From WWII Aircraft Performance P-40 and P-39 performance figures a few days apart at the same airfield.


I believe the critical altitude for the P-39C may be incorrect. The original document shows 13,050' but the retyped (for clarity) chart shows 16,100'. May be just confusing the C with the N whose critical altitude is listed as 16,100. 

The C model is the AAF version of the P-39 that was being produced concurrently with the export P-400 for Britain. The AAF C version was much lighter than the P-400 (7075# vs. 7850#) and consequently had much better performance. Speed was a bit higher (379 vs. 371) but climb was off the chart better at 1000fpm more than the P-400 (3720fpm vs. 2720fpm). 

The C model did not have armor plate and self sealing fuel tanks (like the P-400) but these would not increase the gross weight of the P-39C. The tanks weighed 240# and the armor plate weighed an astonishing 292#. The Brits went a little overboard with the armor using it to protect such items as the oxygen bottles, reduction gear etc. A normal use of the armor plate/glass would have located armor fore and aft of the pilot and behind the oil tank resulting in a weight penalty of about 130# instead of 292#. 

So, add the self sealing tanks (240#) and the more sensible armor (130#). Then lose the 2 .30caliber MGs in the nose (100#) so that the full 30round magazine can be restored to the 37mm cannon (add back 30#). Net weight increase is 300# (240+130-100+30=300#) but the self sealing fuel tanks reduced fuel capacity from 170gal to the standard 120gal. That 50 gallon reduction is equal to 300#. The 300# weight increase was offset by the 300# less fuel resulting in the same 7075# gross weight. The resulting P-39C would have had self sealing tanks, armor plate/glass and armament of a 37mm cannon and two synchronized .50 MGs. And performance at least equal to the Spitfire V currently in service.


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## Shortround6 (Mar 11, 2019)

P-39 Expert said:


> The C model did not have armor plate and self sealing fuel tanks (like the P-400) but these would not increase the gross weight of the P-39C. The tanks weighed 240# and the armor plate weighed an astonishing 292#. The Brits went a little overboard with the armor using it to protect such items as the oxygen bottles, reduction gear etc. A normal use of the armor plate/glass would have located armor fore and aft of the pilot and behind the oil tank resulting in a weight penalty of about 130# instead of 292#.





P-39 Expert said:


> Then lose the 2 .30caliber MGs in the nose (100#) so that the full 30round magazine can be restored to the 37mm cannon (add back 30#).




There were only 20 P-39Cs built out of 80 ordered. The US Army decided they wanted self sealing tanks and armor, they didn't pick u British leftovers.
The contract was amended so that the last 60 planes would incorporate the protective measures along with some other changes. It also delayed delivery of the 60 planes until some of the foreign orders (French order picked up the British for example) were completed or at least initial deliveries made.
These last 60 US planes were the P-39D, plain D not D-1 or D-2. there were a further 394 plain "D"s ordered. 

I would note there was no restoration of the 30 round ammo capacity for the 37mm gun as it never had 30 rounds on the YP-39s, some of which never got any guns at all and the XP-39 never carried guns. 

I believe the reduction gear armor was more of a counterweight than a real need to protect the reduction gear. They needed some weight as far forward in the plane as they could get it and right behind the prop was the far forward location. 

You took an easy 70lbs out of the nose with the .30 cal guns and ammo gone, they added armor to the rear of the plane. 
On the later planes it was and airplane that was not supposed to flown without ammo for the nose guns unless ballast was carried. It was more than a bit sensitive to the center of gravity. 

I would note for the British the 20mm gun weighed about 130lbs compared to the 238lbs of the 37mm gun. and the 20mm ammo and drum were lighter than the 37mm ammo. 

radios are all over the place when it comes to weight (and I have no idea why later P-39s picked up about 50lbs of electrical system weight vs the P-39D. (please note the are weight categories for communications as well as radios in addition to the electrical system.)


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## P-39 Expert (Mar 11, 2019)

Shortround6 said:


> There were only 20 P-39Cs built out of 80 ordered. The US Army decided they wanted self sealing tanks and armor, they didn't pick u British leftovers.
> The contract was amended so that the last 60 planes would incorporate the protective measures along with some other changes. It also delayed delivery of the 60 planes until some of the foreign orders (French order picked up the British for example) were completed or at least initial deliveries made.
> These last 60 US planes were the P-39D, plain D not D-1 or D-2. there were a further 394 plain "D"s ordered.
> 
> ...


I agree with you on the reduction gear armor, it was mostly ballast. Too far away from the pilot to provide any protection and nose gearboxes weren't normally armored on other planes. Bell had a lot of moving parts to design around, what with larger propellers coming along with possibly a mechanical second stage behind the engine. Those radios could be (were) used to restore balance by moving them from the tail to right behind the pilot given the various balance situations. 

I stand by my assertion that the early P-39s (D and F) could have easily been lightened substantially with a resulting performance increase. 

Makes one wonder what the British were thinking when they specified a 7850# plane that should have weighed 7100#. I believe they were ordering ground attack planes since they also ordered P-38s without turbos (or handed propellers). Then when the German invasion didn't materialize the British no longer wanted the P-400 or the turboless P-38.


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## Shortround6 (Mar 11, 2019)

Basically Larry Bell sold a bill of goods to the French and British (and somewhat to the USSAC.)

The British didn't delete the turbo charger by choice. It wasn't ready for combat service. On the P-38 they wanted interchangeable engines with the P-40s they were buying at the same time. Don't forget the British inherited a bunch of French contracts. They could either accept the French specied aircraft, with minor changes like throttle direction and instruments labeled in english and _hope _for early delivery or change the specifications a lot and delay delivery for sure. The US didn't even OK the export of turbochargers until after the first orders were placed. 
lets also remember that Kelsey crashed the XP-38 less that 2 weeks after it's first flight on Feb 11th 1939 and the next P-38 to fly was a YP-38 on sept 16th 1940 which is after the British have 143 non turbo versions on order and 524 MKIIs with turbos on order. The French and British were ordering paper airplanes with nothing but the manufacturer's estimates to go on. 

Larry Bell did test a lightened P-39D, he got the weight down to 6,492lbs but...........
" The same Airacobra was then severely modified by removing the four .30 caliber wing guns and supporting accessoires: all of the gearbox armor plate; the oxygen system; all radio equipment; all instruments* except *the altimeter, airspeed indicator, engine manifold pressure gage, tachometer, temperature and pressure gages; all tools and fixed equipment not needed essential for flight at 5,000ft altitude; all ballast; and four of the eight self-sealing fuel cells. this saved 1,287lbs"

Page 159 "Cobra: Bell Aircraft Corporation" by Birch Mathews. 

We have been over what it took to get a P-400 to meet the British contract requirements in another thread (including the 20 coats of paint sanded between each coat) 

Bell promised a plane he could not deliver.

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## tomo pauk (Mar 11, 2019)

P-39 Expert said:


> Makes one wonder what the British were thinking when they specified a 7850# plane that should have weighed 7100#. I believe they were ordering ground attack planes since they also ordered P-38s without turbos (or handed propellers).



British were not ordering ground-attack planes, neither from USA nor from UK proper.. 
In 1941 and before, RAF was not interested in that type of aircraft. Further, P-38 and P-39 they contracted will be lousy ground-attack aircraft due to absence of bomb racks.



> Then when the German invasion didn't materialize the British no longer wanted the P-400 or the turboless P-38.



They also didn't wanted turboed P-38 by time those materialized.


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## P-39 Expert (Mar 11, 2019)

I don't believe Bell was promising anything once the British got the weight way up to where they knew the plane wouldn't meet spec.

Even after numerous weight increases and the British tests showing the lower speeds they still placed their final order for 505 more. Everybody knew about the extra weight and lower performance. Wasn't a secret.

Point is, the weight should have been a lot lower as shown by the performance of the P-39C at 7100#. Compare it to a Spitfire V. Spitfire V in 1941 was only good for 365-375mph. At 7100# the P-39 would do 379mph and outclimb the Spitfire which only weighed 6600#. That's about the same performance as a Spitfire V except 500# heavier on a less powerful engine. 

The bottom line is the British specified a plane too heavy to meet spec and then tried to cancel the order. The main reason they didn't want the plane was they won the Battle of Britain in late 1940 and there would be no German invasion. Now their internal fighter production would be sufficient and they for sure didn't want to pay for them.


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## MIflyer (Mar 11, 2019)

The tubo was deleted because it actually reduced performance as compared to just a single stage single speed mechanically supercharged V-1710. The turbo installation caused too much drag and the very small size of the P-39 meant there was no place they could put it and not cause that problem.

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## Shortround6 (Mar 11, 2019)

P-39 Expert said:


> I don't believe Bell was promising anything once the British got the weight way up to where they knew the plane wouldn't meet spec.



Source for this?



> Even after numerous weight increases and the British tests showing the lower speeds they still placed their final order for 505 more. Everybody knew about the extra weight and lower performance. Wasn't a secret.


Source for this?



> Point is, the weight should have been a lot lower as shown by the performance of the P-39C at 7100#. Compare it to a Spitfire V. Spitfire V in 1941 was only good for 365-375mph. At 7100# the P-39 would do 379mph and outclimb the Spitfire which only weighed 6600#. That's about the same performance as a Spitfire V except 500# heavier on a less powerful engine.



Source for this



> The bottom line is the British specified a plane too heavy to meet spec and then tried to cancel the order. The main reason they didn't want the plane was they won the Battle of Britain in late 1940 and there would be no German invasion. Now their internal fighter production would be sufficient and they for sure didn't want to pay for them.



I would really love a source for this one.

The French had 165 planes on order in the spring of 1940 (some sources say 170, some say the number changed to 170 when the British took the order over.

Now lets see if we can figure out who knew what when.

"The XP-39B resumed flight trials on November 25, 1939. Empty weight had grown from from 3995 lbs to 4530 lbs, and normal gross weight was up to 5834 pounds from 5550 pounds, and the aircraft STILL didn't have any armament."

The XP-39 was powered by a V-1710-37 (E5) engine rated 1090 hp at an altitude of 13,300 feet. 

" Even in spite of the improved streamlining, the XP-39B suffered a severe degradation in high-altitude performance. Maximum speed fell from 390 mph at 20,000 feet to 375 mph at 15,000 feet, and it now took 7.5 minutes to reach 20,000 feet rather than five minutes. "

Quotes are from Joe Baugher but he makes the common mistake that says the XP-39 flew at 390mph with the turbo, it didn't. Period, end of story. More Bell advertising hype.

then " The XP-39B was damaged in a belly-landing at Wright Field, Ohio on January 6, 1940. It was repaired and resumed flying, later to be demonstrated at Bolling Field in Washington, DC. Unfortunately, the XP-39B was destroyed in an accident after only 28 flying hours. "

" The first YP-39 (40-027) was flown on September 13, 1940 with the 1090 hp V-1710-37 (E5) engine driving a Curtiss Electric propeller. It differed externally from the XP-39B primarily in having a wider-chord vertical tail. The first few YP-39s were initially flown without armament, but subsequent machines were fitted with a 37 mm cannon with 15 rounds, a pair of 0.5-inch machine guns with 200 rounds per gun, and two 0.30-inch machine guns with 500 rounds per gun. All of these guns were mounted in the nose. Some armor protection was provided for the pilot. Empty and normal loaded weights rose to* 5042* pounds and *7000* pounds, respectively. "
"the performance of the YP-39 dropped to a maximum speed of 368 mph at 15,000 feet. An altitude of 20,000 feet could be attained in 7.3 minutes. Service ceiling was 33,300 feet. "

No (or little) armor and no self sealing tanks. Please note that this this first flight was AFTER the British had ordered the 505 additional aircraft.

So Bell Knew about at least some of the weight gain and the fact that the P-39/P-400 was NOT a 400mph airplane. 

The first P-39C flew in Jan of 1941. 
"The P-39C was powered by a 1150 hp Allison V-1710-35 engine. Weights were 5070 pounds empty, 7075 pounds gross (combat weight), and 7300 pounds maximum takeoff. Maximum speed was 379 mph at 13,000 feet. An altitude of 12,000 feet could be reached in 3.9 minutes. "

Accounts vary, The P-39D gets to the first Army units sometime between Feb and April of 1941. British test pilot flies the tricked out P-400 April 27th 1941. 
We also have to conclude that Bell knew the plane was missing the contract performance numbers or they wouldn't have spent so much time working over that one example.

March saw the signing of lend lease and further British orders for lend lease Airacobras were placed but more important to us (or me) is that 3 of the used P-39Cs are declared lend lease and sent to England and arrive July 3rd 1941. 
Joe Baugher again" Although the test pilots praised the general ease of handling of the aircraft, the maximum speed was a shocking 33 mph lower than that anticipated. The fighter proved to be definitely inferior to the Hurricane and Spitfire in climb rate and ceiling, and the 750-yard takeoff run of the Airacobra excluded its operation from some smaller fighter airfields. There was universal shock and dismay among the RAF personnel. What had gone wrong? Bell Aircraft executives later sheepishly admitted that their performance figures had been based on the unarmed and unequipped XP-39 prototype, which weighed a ton less than the armed and equipped P-39C. "

And the P-39C has little armor, no BP glass and no self-sealing tanks, they were sent over to aid in training/familiarization for the P-400?Airacobra Is that began arriving in just a few weeks. 

From Baugher again, your sources may differ
"The Airacobra I was powered by an Allison V-1710-E4 twelve-cylinder V in-line engine rated at 1150 hp for takeoff. Weights were 5462 pounds empty and 7845 pounds normal gross. Maximum speeds were 326 mph at 6000 feet, 343 mph at 10,000 feet, 355 mph at 13, 000 feet, 341 mph at 20,000 feet. Initial climb rate was 2040 feet per minute. With an internal fuel capacity of 100 Imp gal the Airacobra had an endurance of 1 hour 20 minutes at maximum continuous cruising speed at 6000 feet, 1 hour 5 minutes at 12,000 feet, and 1 hour 35 minutes at 20,000 feet. The true airspeeds at these altitudes were 287 mph, 327 mph, and 308 mph, respectively. Under most economical cruise conditions, the endurance increased to 3 hours 20 minutes, the relevant speeds being 183 mph at 6000 feet, 217 mph at 12,000 feet, and 215 mph at 20,000 feet. Under maximum continuous climb conditions, it took 15 minutes to reach 20,000 feet. The operational ceiling was considered to be about 24,000 feet, although there was a marked decrease in performance above 20,000 feet. At the Airacobra's rated altitude of 13,000 feet, it was 18 mph faster than the Spitfire VB. However, the speed fell off rapidly above that height, and the two planes were almost exactly matched at 15,000 feet. At 20,000 feet, the Spitfire VB was 35 mph faster and at 24,000 feet it was 55 mph faster. The ground run of the Airacobra during takeoff was 2250 feet, as compared with 1470 feet for the Hurricane II and 1590 feet for the Spitfire V. "

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## MIflyer (Mar 11, 2019)

Note that the British did not build a high altitude version of the Whirlwind, Beaufighter, or Typhoon - or a two stage supercharged Spitfire until confronted by the FW-190. The Lightning I was designed to use the C series engines employed by the Tomahawk, in order to aid commonality. They did not do high altitude daylight bombing and were not focused on high altitude operations such as the USAAF was.


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## Shortround6 (Mar 11, 2019)

MIflyer said:


> Note that the British did not build a high altitude version of the Whirlwind, Beaufighter, or Typhoon - or a two stage supercharged Spitfire until confronted by the FW-190. The Lightning I was designed to use the C series engines employed by the Tomahawk, in order to aid commonality. They did not do high altitude daylight bombing and were not focused on high altitude operations such as the USAAF was.



I agree with just about all of this.
We should note however that in late 1940 and well into 1941 the Merlin XX and 45 engines were pretty much in class of their own when it came to "high" altitude performance. The Russian AM-35 engine and the two stage R-1830s in the Wildcats were the only real competition. The US was certainly interested in higher altitudes but the turbo charged P-43s and early P-38s weren't really combat ready. I would also note that the Merlins were being produced in far larger numbers than the Russian and American engines at this time.

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## wuzak (Mar 11, 2019)

MIflyer said:


> Note that the British did not build a high altitude version of the Whirlwind, Beaufighter, or Typhoon - or a two stage supercharged Spitfire until confronted by the FW-190. The Lightning I was designed to use the C series engines employed by the Tomahawk, in order to aid commonality. They did not do high altitude daylight bombing and were not focused on high altitude operations such as the USAAF was.



The 2 stage Spitfire was being developed from before the first encounter with the Fw 190, based on the Mk III.

The encounters with the Fw 190 led to the interim Mk IX program, which was initially a Mk V with the Merlin 61, as the definitive Mk VII/VIII versions were developed.


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## P-39 Expert (Mar 12, 2019)

Shortround6 said:


> Source for this? *Birch Matthews "Cobra! Bell Aircraft Corporation 1934-1946"*
> 
> 
> Source for this? *Ditto.*
> ...


 *Please see above for additional comments. Yep, a 7845 pound gross weight will have a detrimental effect on performance. The British did everything in their power to make this plane as heavy as possible so it wouldn't meet spec. The British version weighed 7845#, the AAF version P-39C weighed 7100# and the Spitfire V weighed 6450#. See the attached chart below. The Spitfire V is in red, the P-39C is in black, and P-39K climb at 3000rpm (military power) is green.




*


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## Glider (Mar 12, 2019)

MIflyer said:


> Note that the British did not build a high altitude version of the Whirlwind, Beaufighter, or Typhoon - or a two stage supercharged Spitfire until confronted by the FW-190. The Lightning I was designed to use the C series engines employed by the Tomahawk, in order to aid commonality. They did not do high altitude daylight bombing and were not focused on high altitude operations such as the USAAF was.


I disagree in some way with the first part of this. Westland did develop a high altitude version of the Whirlwind as the Westland Welkin which entered limited production, is clearly based on the same design principles as the Whirlwind.
The idea of developing a high altitude version of the Typhoon and Beaufighter both of which were designs that were low / medium altitude aircraft was never going to happen. Besides, by the time the need arose the RAF had the Spit VII and Mosquito both of which were good for high altitude combat.

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## Glider (Mar 12, 2019)

P-39 Expert said:


> *Please see above for additional comments. Yep, a 7845 pound gross weight will have a detrimental effect on performance. The British did everything in their power to make this plane as heavy as possible so it wouldn't meet spec. [quote\]*
> One day, probably in a far off distant time you might do one of two things:-
> a) supply some evidence that the RAF had a real thing about the P39 and wanted to destoy it's credibility (and supply a reason for this behaviour)
> b) agree that the P39c wasn't combat capable without armour and self sealing fuel tanks

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## tomo pauk (Mar 12, 2019)

Glider said:


> I disagree in some way with the first part of this. Westland did develop a high altitude version of the Whirlwind as the Westland Welkin which entered limited production, is clearly based on the same design principles as the Whirlwind.
> The idea of developing a high altitude version of the Typhoon and Beaufighter both of which were designs that were low / medium altitude aircraft was never going to happen. Besides, by the time the need arose the RAF had the Spit VII and Mosquito both of which were good for high altitude combat.



Welkin was not a high-altitude version of Whirlwind, but a brand new aircraft - new wing of thicker TtC ratio and strong enough to sustain 2-stage Merlins, new were at least central and front fuselage, undercarriage, new cooling systems to cater for much greater cooling load + intercoolers, new fuel system. Old tail will not suffice for much greater engine power.
Neither Typhoon nor Beaufighter were purposely-designed as low/medium altitude aircraft.
Granted, RAF have had enough of hi-alt fighters in it's toolbox, any day between 1920s on, including ww2.


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## Glider (Mar 12, 2019)

tomo pauk said:


> Welkin was not a high-altitude version of Whirlwind, but a brand new aircraft - new wing of thicker TtC ratio and strong enough to sustain 2-stage Merlins, new were at least central and front fuselage, undercarriage, new cooling systems to cater for much greater cooling load + intercoolers, new fuel system. Old tail will not suffice for much greater engine power.


Please note that I said design principles. 
Your comments could apply to a number of aircraft that were radically redesigned such as the P51D to P51H or Me109E to 109F

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## tomo pauk (Mar 12, 2019)

Glider said:


> Please note that I said design principles.
> Your comments could apply to a number of aircraft that were radically redesigned such as the P51D to P51H or Me109E to 109F



You've said:
_Westland did develop a high altitude version of the Whirlwind as the Westland Welkin which entered limited production, is clearly based on the same design principles as the Whirlwind._

so I think my comment is valid.
But, yes, P-51H was a brand-new aircraft vs. P-51D (to the point where only non-NAA items were the same, like MGs or gauges); the Bf 109F seems to be using same fuselage from firewall back as the 109E, but indeed th wing, cooling systems, tail and nose were new.

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## wuzak (Mar 12, 2019)

P-39 Expert said:


> *Please see above for additional comments. Yep, a 7845 pound gross weight will have a detrimental effect on performance. The British did everything in their power to make this plane as heavy as possible so it wouldn't meet spec. The British version weighed 7845#, the AAF version P-39C weighed 7100# and the Spitfire V weighed 6450#. See the attached chart below. The Spitfire V is in red, the P-39C is in black, and P-39K climb at 3000rpm (military power) is green.*



Why would the British, who were in desperate need for front line fighters, reject an aircraft which out-performed the Spitfire?

The Spitfire V had a higher critical altitude, so it is not surprising that the P-39 lightweight special out-climbed it at low altitude.

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## Shortround6 (Mar 12, 2019)

tomo pauk said:


> You've said:
> _Westland did develop a high altitude version of the Whirlwind as the Westland Welkin which entered limited production, is clearly based on the same design principles as the Whirlwind._
> 
> so I think my comment is valid.
> But, yes, P-51H was a brand-new aircraft vs. P-51D (to the point where only non-NAA items were the same, like MGs or gauges); the Bf 109F seems to be using same fuselage from firewall back as the 109E, but indeed th wing, cooling systems, tail and nose were new.



The P-51H used pretty much the same wing, at least aerodynamicly, did it not?
Yes they got rid of the little wing root extensions (which helped house the landing gear) but wasn't the airfoil the same? or slightly stretched to straighten out the leading edge? 
Wing span the same, (or within a 1/4 in) wing area is within 1-2 sq ft. fuselage is a 2 feet longer and the tail is taller (but a lot of planes got bigger/longer tails as they got more powerfuel engines.
Yes you can't make a P-51H out of a P-51D airframe (or at least not without a lot of work) but they are pretty close to each other.

The Whirlwind and Welkin were not anywhere near as close. 

it is not quite as bad as claiming the Lockheed P-58 Chain Lighting _is clearly based on the same design principles as the P-38 Lighting _but the Welkin was a lot further from the Whirlwind than the P-51H was from the P-51D. 









Welkin and Whirlwind





The Welkin was _almost _double the weight of the Whirlwind.


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## jetcal1 (Mar 12, 2019)

Shortround6 said:


> The P-51H used pretty much the same wing, at least aerodynamicly, did it not?
> Yes they got rid of the little wing root extensions (which helped house the landing gear) but wasn't the airfoil the same? or slightly stretched to straighten out the leading edge?
> Wing span the same, (or within a 1/4 in) wing area is within 1-2 sq ft. fuselage is a 2 feet longer and the tail is taller (but a lot of planes got bigger/longer tails as they got more powerfuel engines.
> Yes you can't make a P-51H out of a P-51D airframe (or at least not without a lot of work) but they are pretty close to each other.
> ...


Well, there _is _a family resemblance. 
(Don't laugh, I can see Schumed and the P-51 in a F-5 profile. Or Ted Smith in both a B-26 and the Aerocommander.)


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## MIflyer (Mar 12, 2019)

The Spitfire III was not intended to be a high altitude version, at least not in the same sense as the two stage supercharged Merlin versions. The Spit III was to be powered by the Merlin XX rated at 1,480 hp at 12,250 ft. The Spitfire IV was to be powered by the early single stage supercharged Griffon - still not a high altitude engine.

The Merlin 60 series of two stage two speed supercharged engines was developed as the result of the overflight of Ju-86P and R bombers that operated at too high an altitude for interception by RAF fighters. The British planned to build a version of the Wellington to emulate the Germans, initially to be equipped with radial engines with turbosuperchargers "in the American style" as described by Stanley Hooker. But they wanted a back up engine and that is when Sir Hooker did something utterly brilliant and combined the Merlin engine with the supercharger from the failed Vulture engine used for the Manchester, along with a liquid cooled aftercooler/intercooler. When the FW-190 showed up quite unexpectedly they hung the two stage Merlin on a Spit V airframe and produced the Spitfire IX, an airplane that many German fighter pilots thought was never equalled by the Luftwaffe. 

The British only came up with very high altitude bomber and interceptor after the Germans embarrassed them into pursuing it. The fact that this effort was all but worthless to the Luftwaffe but sealed its doom with coming of the two stage Spitfires and Merlin Mustangs is downright delicious. In contrast the USAAF was working on incorporating turbosuperchargers from the day that General Electric hauled that experimental turbo hooked to a Liberty engine up the side of Pike's Peak and proved it would work.

The F4F and XP-37 were supposed to be high altitude fighters. The turbo in a P-36 airframe with a V-1710 engine worked, and boosted speed above 20,000 ft by 50 mph - but was rather grotesque and must have been terrible to fly.


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## Shortround6 (Mar 12, 2019)

P-39 Expert said:


> Source for this? *Birch Matthews "Cobra! Bell Aircraft Corporation 1934-1946"*



How about some page numbers? 

as for the order for 505, there seems to some confusion, _Initial _order was placed back in the late spring, early summer of 1940. final details. amendments and other details might very well not have been signed until May of 1941, but then why did Bell sign, knowing full well that the planes would not meet contract speed? 

Bell had been through this with the US Army in the fall of 1939. When the French wanted to purchase the P-39/P-400 the Army tried to extract a number of concessions form Bell in return for permission to export. Much like Allison had to forgive $900,00o in past Army debt. Army wanted no increase in cost and no delays in deliver in regards to the 93 planes it had on order at the time. This might be considered fair except the Army also wanted a no cost change order for armor plate and armor glass. The Army also wanted no reduction in performance with these modifications. The Army also wanted the last 18 P-39Cs to have self sealing tanks in restructured wings and didn't want to pay for those either.
If Bell didn't want to absorb their cost the Armies position was that Bell could just add the cost of the improvements to the Army's planes to the cost of the french order.
_"Birch Matthews "Cobra! Bell Aircraft Corporation 1934-1946" pages 156-157. _

On April 3rd the Army and Bell came to agreement (with pressure from Roosevelt). The 13 YP-39s and the first 20 P-39Cs would be delivered as scheduled and without any modifications. However the final 60 would be delayed until Oct and Nov of 1941. These would incorporate the armor plate, armor glass and self sealing tanks. The Army also agreed to a "suitable adjustment of weights, performance, etc" ......."in consideration of the changes to be incorporated" 
_"Birch Matthews "Cobra! Bell Aircraft Corporation 1934-1946" pages 157-158.". _

So Bell knew darn well that extra protection and increased weight would affect performance in March/April of 1940 and had negotiated a contract with the US Army to make those allowances. But they didn't do it with the British? Why the extensively modified test aircraft in April of 1941? 



P-39 Expert said:


> Please see above for additional comments. Yep, a 7845 pound gross weight will have a detrimental effect on performance.* The British did everything in their power to make this plane as heavy as possible so it wouldn't meet spec.* The British version weighed 7845#, the AAF version P-39C weighed 7100# and the Spitfire V weighed 6450#. See the attached chart below. The Spitfire V is in red, the P-39C is in black, and P-39K climb at 3000rpm (military power) is green.



We have asked before, what did the British specify that made the plane so much heavier than the US planes? Specific items of equipment please. 

You do know that if you increase the gross weight of a plane by hundreds of pounds you also have to beef up the structure in order to maintain the same "G" loading and safety margin. I don't know if you need 5lbs of extra material or 50lbs but you need something. 



> I would really love a source for this one. *Just common sense.*



In other words you made it up?


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## Shortround6 (Mar 12, 2019)

MIflyer said:


> The Spitfire III was not intended to be a high altitude version, at least not in the same sense as the two stage supercharged Merlin versions. The Spit III was to be powered by the Merlin XX rated at 1,480 hp at 12,250 ft




A lot depends on exactly what time period we are talking about. 
A Merlin XX compared to a Merlin III was a high altitude engine. In Hurricane it would hold 6lbs of boost to around 23,000 ft in level flight compared to the Merlin III holding 6lbs of boost to about 17,000ft. 

The F4F, even with the two stage supercharger was only good for about 1000hp at 19,000ft (no ram) which is certainly an improvement over the 1000hp at 14,500ft of the two speed R-1830 engine. 

The Merlin III was good for 1310 hp at 9000ft and the Merlin XII was good for 1280hp at 10,500ft. so while not a 30,000ft engine it was better than just about anything else _in service_
in late 1940 and most of 1941.


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## wuzak (Mar 13, 2019)

MIflyer said:


> The Spitfire III was not intended to be a high altitude version, at least not in the same sense as the two stage supercharged Merlin versions. The Spit III was to be powered by the Merlin XX rated at 1,480 hp at 12,250 ft. The Spitfire IV was to be powered by the early single stage supercharged Griffon - still not a high altitude engine.



The XX had a higher rated altitude than the 45 used in the V.

The Griffon IIB wasn't that high altitude rated, but the Mk XII could still do ~390mph at 25,000ft.




MIflyer said:


> The Merlin 60 series of two stage two speed supercharged engines was developed as the result of the overflight of Ju-86P and R bombers that operated at too high an altitude for interception by RAF fighters. The British planned to build a version of the Wellington to emulate the Germans, initially to be equipped with radial engines with turbosuperchargers "in the American style" as described by Stanley Hooker. But they wanted a back up engine and that is when Sir Hooker did something utterly brilliant and combined the Merlin engine with the supercharger from the failed Vulture engine used for the Manchester, along with a liquid cooled aftercooler/intercooler. When the FW-190 showed up quite unexpectedly they hung the two stage Merlin on a Spit V airframe and produced the Spitfire IX, an airplane that many German fighter pilots thought was never equalled by the Luftwaffe.



Not sure that the appearance, in very small numbers, was the reason that the Merlin 60 was being developed, nor the reason for the Wellington VI.

Hooker only tested the concept of the 2 stage supercharger with an impeller from the Vulture.

The first production versions of the 60 series engine had 11.5 inch impellers, while the Vulture's was 12 inches. Later 60 series Merlins had a 12 inch first stage impeller, but not the Vulture's.

Lord Hives suggested putting the Merlin 60 in a Spitfire very early on in development. The first Spitfire equipped with the 2 stage engine was the Mk III. This first flew in September 1941, after several months' conversion work.

This would be the basis of the Spitfire Mk VII/VIII.

The appearance of the Fw 190 pushed them into adapting the 60 series Merlin to the Mk V as an interim measure, since the VII/VIII were some way off production.




MIflyer said:


> The British only came up with very high altitude bomber and interceptor after the Germans embarrassed them into pursuing it. The fact that this effort was all but worthless to the Luftwaffe but sealed its doom with coming of the two stage Spitfires and Merlin Mustangs is downright delicious.



The requirement for the Wellington V and VI came before the Ju 86P started flying over Britain, in small numbers and only as a reconnaissance aircraft. The Ju 86P bombers would not appear over Britain until 1942.




MIflyer said:


> In contrast the USAAF was working on incorporating turbosuperchargers from the day that General Electric hauled that experimental turbo hooked to a Liberty engine up the side of Pike's Peak and proved it would work.



Rolls-Royce had tested a turbo Condor in the 1920s, and concluded that it was not worth the effort.

Bristol had experimented with turbos in the 1930s as well.




MIflyer said:


> The F4F and XP-37 were supposed to be high altitude fighters. The turbo in a P-36 airframe with a V-1710 engine worked, and boosted speed above 20,000 ft by 50 mph - but was rather grotesque and must have been terrible to fly.



The top speed of the YP-37 was 340mph at 10,000ft.

Not a great success as a high altitude aircraft.


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## Ivan1GFP (Mar 13, 2019)

Hello Gentlemen,
It seems to me that it is again a debate on how much of a difference there needs to be before an aeroplane is considered a new design. There are certainly quite a few differences between the P-51D/K and P-51H, but if one goes back a little bit, there are just about as many differences between the P-51/P-51A and the P-51D. The Wing was a different section to allow the guns to be upright, the Armament was increased, the Fuselage changed for a Bubble Canopy, the Radiator is much larger and shaped differently. The entire Fuselage is deeper by about 3-4 inches. Design principles are the same but nothing beyond a few shapes and construction techniques is really quite the same.

Regarding the Whirlwind to Welkin: Eric Brown once made a few unfavourable comments about the Whirlwind and how the design had no ability for improvement because it could not mount any larger engines. How much had to change to make room for larger engines? Is the result just another clean slate design for a twin engine fighter?

Regarding the weights of the P-39C as versus the P-400, obviously some of it was equipment but some of it was also what each service considered "Normal Loaded" weight for the aircraft. The US Army had a habit of specifying only partial loads of fuel, ammunition and even engine oil as "Normal". The British practice may not have been quite the same.
I remember going through these differences early last year and finding the difference to be several hundred pounds.
Just Fuel alone accounts for 120 pounds.
Another amusing thing about the Airacobra is that although the armour tended to be (mostly) in the same places, it often was not the same thickness or weight depending on the exact version of the aircraft.

- Ivan.

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## drgondog (Mar 13, 2019)

Ivan1GFP said:


> Hello Gentlemen,
> It seems to me that it is again a debate on how much of a difference there needs to be before an aeroplane is considered a new design. There are certainly quite a few differences between the P-51D/K and P-51H, but if one goes back a little bit, there are just about as many differences between the P-51/P-51A and the P-51D. The Wing was a different section to allow the guns to be upright, the Armament was increased, the Fuselage changed for a Bubble Canopy, the Radiator is much larger and shaped differently. The entire Fuselage is deeper by about 3-4 inches. Design principles are the same but nothing beyond a few shapes and construction techniques is really quite the same.
> 
> 
> - Ivan.


Ivan the airfoil for the wing for X73 through P-51K was NAA/NACA 45-100. Only the root chord and inboard leading edge of the wing changed for the D/K.The 50 caliber guns could have been mounted vertically in A-36, P-51A/B/C but probably were angled to preserve option to install 20mm (angled) from P-51-NA to A-36. Discussions between Material Command and NAA regarding adding 20mm to P-51B and D were finally killed in November 1943 and the gun mount to 50 caliber was changed to vertical for the P-51D and Subsequent. At that time there were still on-going discussions about P-51F (interceptor- production) with Oldsmobile 20mm guns that would have imposed significant change to LE spar and aft spar for the evolving NACA 66 series wing on the future P-51F, and cancelled.


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## drgondog (Mar 13, 2019)

P-39 Expert said:


> The bottom line is the British specified a plane too heavy to meet spec and then tried to cancel the order. The main reason they didn't want the plane was they won the Battle of Britain in late 1940 and there would be no German invasion. Now their internal fighter production would be sufficient and they for sure didn't want to pay for them.


Not true, They bought the Mustang I, IA, II, III and IV, the P-47D, the F4U, F4F, F6F, and the P-40. They didn't buy the P-39 because it didn't serve a niche that a.) the Spitfire served, b.) it wasn't superior enough to the Hurricane II in CAS role, and c.) it wasn't deemed superior to any of the others named above. 

A second point is that the British were quite well aware in 1941 that the P-39 was a dead end evolution and the P-63 was two+ years away with an unproven engine that had no other airframe to match to simplify logistics. The P-40 (and Mustang I with essentially the same engine until the 1650-1 was installed in the F) was a much better all around choice for the Commonwealth.

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## Milosh (Mar 13, 2019)

Ivan1GFP said:


> The Wing was a different section to allow the guns to be upright,



Can't believe this myth still gets stated. I guess it was forgotten that 4 20mm cannons were fitted in Allison powered P-51s without the wing being changed.

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## Kevin J (Mar 13, 2019)

wuzak said:


> Why would the British, who were in desperate need for front line fighters, reject an aircraft which out-performed the Spitfire?
> 
> The Spitfire V had a higher critical altitude, so it is not surprising that the P-39 lightweight special out-climbed it at low altitude.



Because the threat of invasion had gone when they transferred them to the USSR. The British Cobra would have been a useful asset in repelling a German invasion, it had a cannon and much more armour than the P-39D.


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## Peter Gunn (Mar 13, 2019)

Going back to the P-51H, I was under the impression that it was a whole different design than the D and shared very few, if any, components. Wing, tail and if I'm not mistaken, even the thrust line was altered to give better over the nose visibility for deflection shooting.

If I'm wrong I will stand (well, sit really) corrected.

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## wuzak (Mar 13, 2019)

Kevin J said:


> Because the threat of invasion had gone when they transferred them to the USSR. The British Cobra would have been a useful asset in repelling a German invasion, it had a cannon and much more armour than the P-39D.



The P-39D had a canon too.

Spitfires were held back from overseas deployment well into 1941, even 1942, to keep a strong defence.

Instead, Hurricanes and P-40s were shipped off to other theatres and Commonwealth nations.

If the P-39 was the equal of, or superior to, the Spitfire V the British would have laid their hand on as many as they could get.

It may have been used in ground attack roles, but that was not the primary reason the British were planning to acquire the P-39. It possibly wasn't even a consideration.


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## Shortround6 (Mar 13, 2019)

Kevin J said:


> Because the threat of invasion had gone when they transferred them to the USSR. The British Cobra would have been a useful asset in repelling a German invasion, it had a cannon and much more armour than the P-39D.



By the fall of 1941 the British were fitting two 20mm cannon in the Spitfire and the Hurricane IIc was starting to show up with four 20mm cannon, and AIracobra I with a single 20mm (and drum fed) was hardly a wonder weapon for anti-invasion duties. The British never ordered or got an AIracobra with a 37mm. 

I am really wondering about the_ much_ more armor bit too. The P-39D, when ordered, had about 250lbs of armor. Since you have P-39Ds, D-1s and D-2s not to mention the reposesed P-400s (which the British had paid for cash) it is quite possible the armor fit changed a bit. AHT (Dean) says that a P-39 D had 262.2lbs of armor and BP glass, a P-39D-2 had 246.4lbs and a P-400 had 265.6lbs while a Q-1 had 193lbs. 

Now these are the weights form a specific aircraft and are going to fluctuate a bit from aircraft to aircraft on the procution line so I wouldn't pay attention to the tenths of pound or even a difference of 2-5 lbs out of 260lbs. 1-2% variation being common. Some sources say the British planes had a bit over 290lb which even if true is only 30lbs more than a P-39D. It alos makes you wonder what the US took out when they got the British Airacobras and just called them P-400s?

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## tomo pauk (Mar 13, 2019)

Shortround6 said:


> The P-51H used pretty much the same wing, at least aerodynamicly, did it not?
> Yes they got rid of the little wing root extensions (which helped house the landing gear) but wasn't the airfoil the same? or slightly stretched to straighten out the leading edge?
> Wing span the same, (or within a 1/4 in) wing area is within 1-2 sq ft. fuselage is a 2 feet longer and the tail is taller (but a lot of planes got bigger/longer tails as they got more powerfuel engines.
> Yes you can't make a P-51H out of a P-51D airframe (or at least not without a lot of work) but they are pretty close to each other.



Lightweigth Mustangs used different airfoil series, that was also thinner (% - wise) with 15.5% TtC at root; flaps and airlerons were of different size, different sweepback, washout and MaC. New wing also had bigger fuel tanks.


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## MIflyer (Mar 13, 2019)

The XP-37's critical altitude was 20,000 ft and the YP-37's critical altitude was 25,000 ft. That is where their highest performance was, not at 10,000 ft, but up where the B-17's were flying. Highest speed was 331 MPH, so they missed the promised 340 mph, and the USAAC lost interest, choosing instead to buy the P-40 with the V-1710 and no turbo. But while the basic bare bones prototype P-40 could hit about 365 MPH, that was at a much lower altitude. The YP-37 was much faster above 20,000 ft, probably about 50 mph faster and had a higher maximum ceiling as well.

The Vulture was 2592 cubic inches so putting that supercharger as the first stage of the two stage Merlin gave that "little" engine (smaller displacement than a V-1710 or even the engine used in the A6M3) world class performance..


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## MIflyer (Mar 13, 2019)

The RAF tested the 37MM of the P-39 and found that it would not penetrate the armor of the German tanks, while the Vickers 40MM gun on the Hurricane IID did. The USAAF said that the P-39's gun could crack tanks but the actual tests proved that it could not.

The "tank-busting" P-39 is a myth.

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## Shortround6 (Mar 13, 2019)

MIflyer said:


> The Vulture was 2592 cubic inches so putting that supercharger as the first stage of the two stage Merlin gave that "little" engine (smaller displacement than a V-1710 or even the engine used in the A6M3) world class performance..



The Vulture supercharger _impeller _happened to be handy and about the right size for a _proof of concept test rig_. After that it's usefulness rather diminishes. It gave "close" to the desired airflow at the altitudes they were interested in. 

I would note that the RR had a pretty good idea of what the Merlin could or could not do as a basic engine back in 1938/39 when they worked on the "Speed Spitfire"


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## Shortround6 (Mar 13, 2019)

MIflyer said:


> The RAF tested the 37MM of the P-39 and found that it would not penetrate the armor of the German tanks, while the Vickers 40MM gun on the Hurricane IID did. The USAAF said that the P-39's gun could crack tanks but the actual tests proved that it could not.
> 
> The "tank-busting" P-39 is a myth.



Well, judging the ability of your anti-tank guns against your own tanks might lead to some faulty conclusions 






More seriously. armor penetration is strongly related the amount of energy that can be delivered per sq in (sq cm ) of target area (area of the projectile).

The American AP projectile for the 37mm aircraft gun weighed 753 grams and had 116,000 Joules of energy at the muzzle.

The German 37mm AP projectile as used by the JU 87 (and others) weighed 680 grams but it's higher velocity gave 218,000 Joules. 

The Russian NS-37 gun used a 760 gram AP projectile and had 294,000 Joules at the Muzzle.

The British Vickers S gun used a bit bigger diameter shot but but the MK I AP weighed 1,130 grams and had 214,000 Joules while the MK VI shot weighed 1,360 grams and had 221,ooo Joules. 

A 37mm needs to make a hole about 3.4 times bigger than a 20mm, so the American 37mm was actually a worse hole puncher than some 20mm cannon.

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## drgondog (Mar 13, 2019)

Peter Gunn said:


> Going back to the P-51H, I was under the impression that it was a whole different design than the D and shared very few, if any, components. Wing, tail and if I'm not mistaken, even the thrust line was altered to give better over the nose visibility for deflection shooting.
> 
> If I'm wrong I will stand (well, sit really) corrected.


IIRC, the P-51H shared zero assemblies with the P-51D/K, was longer, thrust line different, wing different, empennage different, lower cooling system cowl different , scoop design different, ~13 common parts (brackets, switches, plates), tires smaller, tall tail, wing area greater, airfoil different, plan form of wing different -easier to maintain, faster, climbed better, higher ceiling - but the name remained Mustang.


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## pbehn (Mar 13, 2019)

drgondog said:


> IIRC, the P-51H shared zero assemblies with the P-51D/K, was longer, thrust line different, wing different, empennage different, lower cooling system cowl different , scoop design different, ~13 common parts (brackets, switches, plates), tires smaller, tall tail, wing area greater, airfoil different, plan form of wing different -easier to maintain, faster, climbed better, higher ceiling - but the name remained Mustang.


Well it looked like a Mustang so it was called a Mustang, what else would you call it? If you look at the variations that constitute a "Hurricane Mk I" or a Spitfire Mk I and then the whole Spitfire/Seafire series, what constitutes a new "marque" is just a matter of looks/fashion and bureaucracy

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## FLYBOYJ (Mar 13, 2019)

pbehn said:


> Well it looked like a Mustang so it was called a Mustang, what else would you call it? If you look at the variations that constitute a "Hurricane Mk I" or a Spitfire Mk I and then the whole Spitfire/Seafire series, *what constitutes a new "marque" *is just a matter of looks/fashion and bureaucracy


In the case of the P-51*H* - "A letter"


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## pbehn (Mar 13, 2019)

FLYBOYJ said:


> In the case of the P-51*H* - "A letter"


In the case of a Hurricane Mk ! you can change the engine, the prop, the wings from dope to metal, armour as long as it still looked like a Hurricane that's what it was a Hurricane MkI. Even more so for a Spitfire, they even changed the prop rotation, engine, wings and pretty much the whole thing, but somehow they all look like Spitfires.


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## Shortround6 (Mar 13, 2019)

The thing is the Hurricane, Spitfire and Mustangs (Allison's to Merlins and the D/K to the H) and a few others the changes were somewhat incremental, the planes had the same general purpose and the wings, when changed didn't "fly" much different than the old wings. See complaints about the Supermarine Spiteful. 

When you go from the Whirlwind to the Welkin you not only nearly double the weight, you go from a 45 ft wing span to 70ft (one foot less than a big wing B-26 Marauder ) the wing area goes up 72%, we are not talking about clipping wing tips or fitting extensions here. You also nearly double the power in one jump. 

A lot of people claim the grumman F6F was developed from the F4F but a quick look at the companies unbuilt paper studies shows that they had given up any hope of developing the f4F airframe/wing started over with a clean sheet of paper. This does not mean that some details or general shapes were not the same.


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## GrauGeist (Mar 13, 2019)

MIflyer said:


> The RAF tested the 37MM of the P-39 and found that it would not penetrate the armor of the German tanks, while the Vickers 40MM gun on the Hurricane IID did. The USAAF said that the P-39's gun could crack tanks but the actual tests proved that it could not.
> 
> The "tank-busting" P-39 is a myth.


Where were they aiming?
Mantle, Glacis, Skirt, engine compartment (rear) or top plating?


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## Shortround6 (Mar 13, 2019)

Most logical targets would be the sides and rear of both the hull and the turret. Aiming at the top is near useless, if you are in a 30 degree dive then your impact angle on the top deck or turret top is 60 degrees, The physical path through the top armor is doubled and when you add in the tendency of projectiles to skid/ricochet then the armour will act 2 1/2 to 3 times is nominal thickness, if you are less than 30 degrees it just gets worse fast. If you are diving at more than 30 degrees how close can you get before you have to pull out of the dive?

The low velocity 37mm just doesn't have the punch. Please note that the American 37mm anti-tank and tank guns (and the 37mm AA gun) used heavier projectiles at higher velocities.

they had 317,000 to 326,000 Joules of ME depending on which load and exactly which gun. 

If you think you can aim at and hit an engine grate your ego is probably writing checks your actual marksmanship can't cash. The M4 37mm gun only fired about 2.5 rounds per second so you aren't going to get many chances and at 300mph the plane is moving 440 feet per second. Plane is moving 176 ft between each round fired?

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## GrauGeist (Mar 13, 2019)

I should have also added was it a static test? If so, was the cannon elevated or at ground level?
If it was from a P-39 in a simulated attack, what was the closing speed, altitude at the start of the attack and how many times was the test done in order to create an average?

I am fully aware that there is an optimum angle for an attacking aircraft to use to fully exploit the projectile's ability to defeat certain armor.
But in combat, perfect angles are not always easy to achieve. Example: tank on the move across broken terrain versus a tank moving along a road. How high is the attacking aircraft when the tank is spotted, is the tank's rear presented or is it safe to go around in order to make an attack run before ground fire starts up?

Obviously, only megastar combat sim champs can hurl a cannon shell into the center of a engine vent (or a proton torpedo into a thermal vent the size of a Womp rat) but in reality, not every pass is going to offer the perfect formula for success.


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## MIflyer (Mar 14, 2019)

Remember that initially the P-51B was designated the P-78. And you could make a good argument for the A-36 to have a P-51 designation and the B-50 to be a B-29 model. While the F-84F as produced had very little in common with the straight winged F-84 models.

As for the 37MM tests they must have been shooting at the front of the tank, in a static test. Rudel was careful to aim at the top or the rear engine cover but most people are happy to hit it anywhere.


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## Shortround6 (Mar 14, 2019)

GrauGeist said:


> I should have also added was it a static test? If so, was the cannon elevated or at ground level?
> If it was from a P-39 in a simulated attack, what was the closing speed, altitude at the start of the attack and how many times was the test done in order to create an average?
> 
> I am fully aware that there is an optimum angle for an attacking aircraft to use to fully exploit the projectile's ability to defeat certain armor.
> But in combat, perfect angles are not always easy to achieve. Example: tank on the move across broken terrain versus a tank moving along a road. How high is the attacking aircraft when the tank is spotted, is the tank's rear presented or is it safe to go around in order to make an attack run before ground fire starts up?



By the time the P-39 shows up in North Africa the British had been shooting at German tanks for well over a year with ground guns. They had a pretty good idea how thick the German armor was on the MK III and MK IV tanks and that was pretty much 30mm on the turret sides and rear and 30mm on the hull sides. The Front of the tanks was 30mm an the very oldest models (few left in service at this time?) with 50 mm being much more common on both and some MK IIIs had 60mm on the hull front (a 30mm layer added to the base 30mm) and some of the MK IIIs had thicker armor on the hull rear. When you get to the long barreled MK IIIs some had an extra 20mm plate spaced off the base 50mm turret front or drivers plate but stll had 30mm turret sides and rear and 30mm hull sides.
This was all well known from shooting at them (and capturing wrecks) with 2pdr AT guns, 25pdrs and assorted other guns. 
Just like the US 37mm the British had a couple of different 2pdrs. The 2pdr ground AT gun (and tank gun) used a much bigger cartridge case to hold more powder and had a much higher velocity than the 2pdr AA gun which was the source of the ammo for the 2pdr Vickers S gun used in Hurricanes. 







British had been using the cartridge on the right in the M3 Stuart tanks (and turret of the M3 grant), it should NOT take extensive, carefully conducted tests to figure out that the cartridge 2nd from the left is NOT going to go through armor that the one on the right won't go through at similar distances, even with 300-450 fps added to the ground velocity. 

Likewise comparing the British 2pdr Vickers S gun and the American 37mm M4 used in the Airacobra should have clued people in that the American 37mm was NOT going to go through any where near as much armor without bothering with all sorts of firing trials/tests conducted by flying planes. Weight of shot, velocity of the shot and size of the hole you are trying to make. The two guns are not in same league. 

It always helps to have a good margin of surplus gun power to make up for firing from less than ideal distances or angles even on the thinner parts of tanks. The 37mm M4 gun was only going to work under the most favorable of conditions it at all.

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## MIflyer (Mar 14, 2019)

Despite the deletion of the turbo the USAAF was NOT focused on using the P-39 for ground attack, as some have claimed. The engine was set up for max speed at about 15K ft. Contrast that with the A-36A, which was set up for max speed at 5000 ft.

Thus the 37MM gun in the P-39 was designed for use in air-to-air combat. It was effective against some ground targets; one pilot reported it did a nice job on German barges in the Med. But tanks? No. VW beetles? Sure!

One of the really inexplicable things was that when the RAF fired the P-39's 37MM gun on the ground it always jammed after the first shot. They figured out that the extractor lever was too long, cut it down and then it worked Okay. Why the USAAF would have an airplane with that kind of design defect is unknown. Maybe it needed the airflow to eject the shells?


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## Glider (Mar 14, 2019)

MIflyer said:


> Despite the deletion of the turbo the USAAF was NOT focused on using the P-39 for ground attack, as some have claimed. The engine was set up for max speed at about 15K ft. Contrast that with the A-36A, which was set up for max speed at 5000 ft.
> 
> Thus the 37MM gun in the P-39 was designed for use in air-to-air combat. It was effective against some ground targets; one pilot reported it did a nice job on German barges in the Med. But tanks? No. VW beetles? Sure!
> 
> One of the really inexplicable things was that when the RAF fired the P-39's 37MM gun on the ground it always jammed after the first shot. They figured out that the extractor lever was too long, cut it down and then it worked Okay. Why the USAAF would have an airplane with that kind of design defect is unknown. Maybe it needed the airflow to eject the shells?


There were a number of defects in the P39 which should have been identified well before they reached the RAF. Unfortunately this was quite common in other aircraft such as the early B17's.


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## Peter Gunn (Mar 14, 2019)

drgondog said:


> IIRC, the P-51H shared zero assemblies with the P-51D/K, was longer, thrust line different, wing different, empennage different, lower cooling system cowl different , scoop design different, ~13 common parts (brackets, switches, plates), tires smaller, tall tail, wing area greater, airfoil different, plan form of wing different -easier to maintain, faster, climbed better, higher ceiling - but the name remained Mustang.


Good to know I haven't lost ALL my marbles, was worried there for a while.

Also, the H was as beautiful as any of the breed, an excellent standard bearer to carry the name.

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## P-39 Expert (Mar 14, 2019)

wuzak said:


> Why would the British, who were in desperate need for front line fighters, reject an aircraft which out-performed the Spitfire?
> 
> The Spitfire V had a higher critical altitude, so it is not surprising that the P-39 lightweight special out-climbed it at low altitude.


Money. By the time the P-300s were coming off the line the British 1. no longer needed them and 2. Couldn't (didn't want to) pay for them.


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## Glider (Mar 14, 2019)

P-39 Expert said:


> Money. By the time the P-300s were coming off the line the British 1. no longer needed them and 2. Couldn't (didn't want to) pay for them.


You do of course have evidence for this statement don't you?


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## pbehn (Mar 14, 2019)

Glider said:


> You do of course have evidence for this statement don't you?


He didn't last time, its like groundhog day.


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## Shortround6 (Mar 14, 2019)

Does anybody really know how many the British did pay for?

From Joe Baugher's site. 

"By the time this decision was made, production of British-contract Airacobras had reached four a day at Bell's Buffalo plant. The initial contract for 170 planes (RAF serials AH570 thru AH739) had been completed before the end of September, and all but six of these planes had actually been shipped to Britain. However, many of them remained in their crates and were shipped directly to the Soviet Union without being opened. Somewhere between 80 and 100 Airacobras were assembled and flown in Britain by the end of 1941. They were gathered at maintenance units for final modification before being re-crated and shipped to the Soviet Union during 1942. In all, the Soviet Union received 212 of the British Airacobras (some of them shipped direct from the USA), but 49 more were lost at sea en route. "

and

"After Pearl Harbor, the USA found itself in desperate need of aircraft to stem the Japanese onslaught in the Pacific. Consequently, nearly 200 of the British direct-purchase Airacobras still in the USA were promptly requisitioned by the USAAC. Although they were similar to the USAAC's P-39Ds, they were not identical and were known by the USAAC under the non-standard designation of P-400. "

"The P-400s also saw some use closer to Britain. 179 of the Airacobras sent to Britain were re-acquired by the USAAF and were sent to North Africa to join the Twelfth Air Force. "

This seems a bit confusing and needs clarification. It also appears that unless the Americans refunded the money the British had paid up front for the P-400s Britain didn't _get out of the contract. _

Another book on "lend-lease" aircraft may confuse the British cash purchase with lend lease. It lists the Martin Marylander as lend lease including the ex french ones.

In any case for the Airacobra out of 678 aircraft There are 5 batches of aircraft.

Out of the first batch of 170 planes (serial numbers AH570-739) about 80 were used by the RAF, some were used by the USAAF and 94 are confirmed (with serial numbers listed) as going to Russia.

The next batch of 121 aircraft ( serial numbers AP264-384) was taken over by the USAAF, 12 were lost at sea in transit, 20 went to Russia.

3rd batch of 84 aircraft (serial numbers BW100-183) was delivered but but many handed over to the USAAF, others shipped to Russia BW114 went to the RAF.

4th batch of 300 aircraft (serial numbers BX135-424) Majority taken over by the USAAF, others shipped to Russian at least 17 lost at sea.

5th Batch was the 3 ex USAAF P-39C aircraft sent to England for evaluation/training/familiarization. These last 3 planes were lend lease. 

So again, how many did the British wind up paying for or were they given credit for the planes the USAAF wound up getting?

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## BiffF15 (Mar 14, 2019)

Shortround6 said:


> Does anybody really know how many the British did pay for?
> 
> From Joe Baugher's site.
> 
> ...



How the heck did the accountants keep up with who owed how much to whom, and who got paid and how / when?  What a mess...

Cheers,
Biff


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## Kevin J (Mar 14, 2019)

BiffF15 said:


> How the heck did the accountants keep up with who owed how much to whom, and who got paid and how / when? What a mess...
> 
> Cheers,
> Biff



This is my take on deliveries (includes lost at sea) to Russia but correct me as I may be wrong:-

P-39D-1 336 Lend-lease
P-39D-2 50 Lend-lease
Cobra I 212 British purchase
P-39K 50 Lend-lease
Total = 648 So 27 short of total British order of 675

Plus,
P-39N 1097 Lend-lease
P-39Q 3291 Lend-lease

So,
Grand Total = 5036 so figure that one out.

Interestingly, Australia got,

P-39D-2 12 Lend-lease ?
P-39F 10 Lend-lease ?

and Britain got,
P-39C 3 Lend-lease

Add these last 3 numbers to the 648 and you get 673, almost the original number ordered by the Brits. Is there any accounting connection here.

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## P-39 Expert (Mar 15, 2019)

Glider said:


> You do of course have evidence for this statement don't you?


Need: The P-400 was ordered by France in 1940. After France fell the contract was assumed by the British. The British won the Battle of Britain in the fall of 1940. That meant there would be no invasion of Britain so they no longer needed those planes that started being delivered in 1941.

Ability to pay: Britain had been standing alone against Germany since the fall of France. The war was very expensive for them. This was in 1941 before Pearl Harbor and the US being actively involved.


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## pbehn (Mar 15, 2019)

BiffF15 said:


> How the heck did the accountants keep up with who owed how much to whom, and who got paid and how / when? What a mess...
> 
> Cheers,
> Biff


It all became academic, at the end perfectly good aircraft were scrapped or thrown off carriers so they didn't have to be paid for with the full agreement of the USA.


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## Peter Gunn (Mar 15, 2019)

All this P-39 talk brings to mind a book I have written in the early 1980's about the Eagle Squadrons, I'll have to dig it out this weekend. There were a bunch of interviews and such in it and at one point I think there were about a dozen pilots from said Eagles tasked with transporting some P-39's slated for duty in Africa I believe. Not sure like I said, I'll have to dig up the book, but as I recall, they were less then enthusiastic about the P-39 after flying combat ops in Spitfires.


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## Peter Gunn (Mar 15, 2019)

Glider said:


> You do of course have evidence for this statement don't you?





P-39 Expert said:


> *SNIP*
> 
> Ability to pay: Britain had been standing alone against Germany since the fall of France. The war was very expensive for them. This was in 1941 before Pearl Harbor and the US being actively involved.



I don't mean to be picky P-39, but that's not evidence...


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## wuzak (Mar 15, 2019)

P-39 Expert said:


> Need: The P-400 was ordered by France in 1940. After France fell the contract was assumed by the British. The British won the Battle of Britain in the fall of 1940. That meant there would be no invasion of Britain so they no longer needed those planes that started being delivered in 1941.
> 
> Ability to pay: Britain had been standing alone against Germany since the fall of France. The war was very expensive for them. This was in 1941 before Pearl Harbor and the US being actively involved.



The real reason was that Britain had the P-39 fitted with the necessary equipment for fighter operations in the ETO, as experience showed them, and found the performance wanting.

Actually, it was shit.


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## Shortround6 (Mar 15, 2019)

P-39 Expert said:


> Need: The P-400 was ordered by France in 1940. After France fell the contract was assumed by the British. The British won the Battle of Britain in the fall of 1940. That meant there would be no invasion of Britain so they no longer needed those planes that started being delivered in 1941.
> 
> Ability to pay: Britain had been standing alone against Germany since the fall of France. The war was very expensive for them. This was in 1941 before Pearl Harbor and the US being actively involved.




Hardly evidence. 

as noted before, the British took delivery and paid for all the other aircraft they ordered during the same time period.

You have yet to show any evidence that 

1. The British got out of the contract.
2. The British refused delivery of the aircraft.
3. The British got any of their money back. 

Now there is a bunch of pure malarkey in books and on the internet Like "Still, the British needed a high-altitude fighter and dumped their P-39s on the USAAC; the rest of the order was cancelled. "

Now as we have seen, the order*s *(pural) were not canceled, the recipient's changed but the orders were not canceled (the planes were built, sometimes with different details and designations) 

The British were busy dumping their P-39s on the Russians, not the the USAAC. 

Then we have one of my favorite explanations to a lot of things, TIMING, by the end of Dec 1941 the USAAC had taken delivery of 404 P-39Ds (Birch Mathews book) which is a considerable number BUT, according to AHT (Dean) Bell built 926 Airacobras in 1941 total and 191 of them were in Dec. 
There had only been about 20 Airacobras built in the first 4 months of 1941 and those were the P-39Cs and one or two of the British aircraft (including the Special). Bell managed to get production up to 50 aircraft in July and then went to triple digits for the rest of the year. 

However we have a real discrepancy in the numbers. 926 Airacobras minus 20 C leaves 906. 675 British planes plus 404 P-39Ds is 1079 planes. We are off by 173 planes. 
Either there aren't anywhere near as many P-39Ds as Mathews claims or the British order*s* are not complete at this time. 
Some of these figures may not be accurate as even the same books do not agree with themselves. AHT (Dean) claims in a different chapter that as of Pearl Harbor 600 P-39s had been built for the US Army. They equipped 5 fighter Groups, not 

AHT (Dean)also claims that as of Dec 31st 1941 Bell had built 926 Airacobras. 429 P-39Ds and 229 P-39Fs. These numbers leave just 238 British Airacobra Is built in 1941?????

The British didn't need to "dump"their now unwanted P-39s on the USAAC, the USAAC was scrambling for just about every airplane it could get.

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## Shortround6 (Mar 15, 2019)

wuzak said:


> The real reason was that Britain had the P-39 fitted with the necessary equipment for fighter operations in the ETO, as experience showed them, and found the performance wanting.
> 
> Actually, it was shit.


 I would note that the US fitted pretty much the same equipment to the P-39D (ordered in the spring of 1940) got pretty much the same weight gain and pretty much the same drop in performance. Only thing is the US Army knew it, and the Army and Bell negotiated the contracts to suit after a long and sometimes contentious negotiation. 
So far there is no evidence the British added anything the USAAC didn't. In fact they used a lighter cannon.


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## P-39 Expert (Mar 15, 2019)

The British never got out of the contract because the Japanese bombed Pearl Harbor and the AAF needed all the planes they could get, including the P-400s that Britain didn't want.

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## pbehn (Mar 15, 2019)

The British were in need of good aircraft, they would have taken Allison engine Mustangs any time up to the end of the war. The P-39 was not better than what the British had for the uses they had and with the invasion of Russia and Pearl Harbor the British need for aircraft was third in any queue. In addition to P-39s going to Russia so were Hurricanes.


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## P-39 Expert (Mar 15, 2019)

Shortround6 said:


> I would note that the US fitted pretty much the same equipment to the P-39D (ordered in the spring of 1940) got pretty much the same weight gain and pretty much the same drop in performance. Only thing is the US Army knew it, and the Army and Bell negotiated the contracts to suit after a long and sometimes contentious negotiation.
> So far there is no evidence the British added anything the USAAC didn't. In fact they used a lighter cannon.


The P-39D was about 200# lighter than the export P-400/P-39D-1 which were virtually alike. Both were intended as export models while the D was for the AAF. Empty the D weighed 5462# and the F weighed 5409# because the only difference in the D and F was the hydromatic propeller on the F which was about 50# lighter than the Curtiss Electric prop on the D. With a load of 1700# those Ds and Fs would have weighed 7162# and 7109# respectively and had performance like the P-39C in post #388. That's fully equipped with self sealing tanks, revised armor plate/glass, 120 gallons of fuel and armed with the 37mm canon and twin .50 caliber MGs. 

The performance difference was all weight since the aerodymanics and engines were the same. All that performance lost over 4 .30 caliber MGs and about 120 pounds of armor plate that wasn't needed. Items that could be removed in a short amount of time at a forward air base. Would you rather have the 4 peashooter MGs and useless armor plate (due to location) or the extra 1000fpm climb? The Russians figured this out after they tested the first Airacobras delivered to them.


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## pbehn (Mar 15, 2019)

P-39 Expert said:


> The P-39D was about 200# lighter than the export P-400/P-39D-1 which were virtually alike. Both were intended as export models while the D was for the AAF. Empty the D weighed 5462# and the F weighed 5409# because the only difference in the D and F was the hydromatic propeller on the F which was about 50# lighter than the Curtiss Electric prop on the D. With a load of 1700# those Ds and Fs would have weighed 7162# and 7109# respectively and had performance like the P-39C in post #388. That's fully equipped with self sealing tanks, revised armor plate/glass, 120 gallons of fuel and armed with the 37mm canon and twin .50 caliber MGs.
> 
> The performance difference was all weight since the aerodymanics and engines were the same. All that performance lost over 4 .30 caliber MGs and about 120 pounds of armor plate that wasn't needed. Items that could be removed in a short amount of time at a forward air base. Would you rather have the 4 peashooter MGs and useless armor plate (due to location) or the extra 1000fpm climb? The Russians figured this out after they tested the first Airacobras delivered to them.


Wasn't the performance difference in part due to filling and polishing of an aircraft for test? I am sure we went through all this.


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## Shortround6 (Mar 15, 2019)

P-39 Expert said:


> The British never got out of the contract because the Japanese bombed Pearl Harbor and the AAF needed all the planes they could get, including the P-400s that Britain didn't want.




Well, we are part way there.

Now we just need the proof that the British KNEW in the fall of 1940 that there would be no German invasion in the spring of 1941 so they could try to get out of the contracts.
We just the proof that the British specified hundreds of pounds of "equipment" that the USAAC was NOT specifying at the same time for their P-39Ds.
and we need the PROOF that the British did this in 1940 with the intention of getting out of the contracts 9-15 months before the planes were to be deleivered and 6-9 months before lend lease was passed into law (giving them planes for "free")


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## P-39 Expert (Mar 15, 2019)

pbehn said:


> Wasn't the performance difference in part due to filling and polishing of an aircraft for test? I am sure we went through all this.


I believe you are thinking of the April 1941 tests of the P-400 with the smaller tail, polished surface, etc. I don't believe any of the govt/military tests in wwiiaircraftperformance.org showed a polished P-39. That's only good for 2-3mph anyway.


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## pbehn (Mar 15, 2019)

P-39 Expert said:


> I believe you are thinking of the April 1941 tests of the P-400 with the smaller tail, polished surface, etc. I don't believe any of the govt/military tests in wwiiaircraftperformance.org showed a polished P-39. That's only good for 2-3mph anyway.


We did go through it all at length though, didn't we, starting off with the same statement about the British not wanting to pay?


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## P-39 Expert (Mar 15, 2019)

Shortround6 said:


> Well, we are part way there.
> 
> Now we just need the proof that the British KNEW in the fall of 1940 that there would be no German invasion in the spring of 1941 so they could try to get out of the contracts.
> We just the proof that the British specified hundreds of pounds of "equipment" that the USAAC was NOT specifying at the same time for their P-39Ds.
> and we need the PROOF that the British did this in 1940 with the intention of getting out of the contracts 9-15 months before the planes were to be deleivered and 6-9 months before lend lease was passed into law (giving them planes for "free")


French/British ordered the P-400 in 1940 because they DIDN'T know that they would win the battle of Britain in the fall of that year. After they DID win the BoB they no longer needed the P-400. They didn't try to get out of paying for them until they knew that they didn't need them.

See post #442 for the weight differences.


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## Shortround6 (Mar 15, 2019)

P-39 Expert said:


> I believe you are thinking of the April 1941 tests of the P-400 with the smaller tail, polished surface, etc. I don't believe any of the govt/military tests in wwiiaircraftperformance.org showed a polished P-39. That's only good for 2-3mph anyway.



What Bell did was worth a whole lot more than 2-3mph. More like 15-20mph minimum


I also have serious doubts about how much yanking the four .30 cal guns is going to do for performance. 
Yanking the under wing .50s from a P-63 was only supposed to be good for 110fpm in climb. 
The under wing wing .50s weigh more than the .30s,in fact the four .30 cal guns weigh about 95lbs. This does not include mounts/brackets and accessories. The under wing .50 cal guns on late P-39s and P-63s went 220lb for the pair of guns, the pods, mounts/brackets stc. 

The 4 guns in the P-39 wing had the exposed barrels and cartridge ejection slots to cause drag. 
The P-63 had





Now perhaps the test of the P-63 was falling into the ends of the allowable or expected errors?

However please note (as I have mentioned before) that a Spitfire MK V could be fitted with a 90 imp gallon drop tank, gross weight increased by 790lbs and yet it's climb performance only went down to 10 minutes to 20,000ft from 8 minutes and to 14.000ft (critical altitude at climb speed) it needed 6.6 minutes instead of 5.35 (an increase of 1 1/4 seconds) 
while the P-39 carrying 2 extra ,30 cal guns (2 had been moved from the nose) , more ammo and a bit of extra armor loses 1000ft a minute????


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## Shortround6 (Mar 15, 2019)

P-39 Expert said:


> French/British ordered the P-400 in 1940 because they DIDN'T know that they would win the battle of Britain in the fall of that year. After they DID win the BoB they no longer needed the P-400. They didn't try to get out of paying for them until they knew that they didn't need them.
> 
> See post #442 for the weight differences.



So, the British didn't increase the weight until the fall of 1940, months after the initial order? 
And months after they knew (and the USAAC knew) they wanted armor and self sealing tanks?

Differences for the British _might_ be different oxygen equipment, different radios, fitting IFF gear (I don't know if the US was using it at the time) 
Or other bits and pieces like landing lights or somthing

the difference in armor is about 40lbs at the most and may be nothing depending on which source or which airplane is tested/ weighed. 
The difference in .303 ammo and US .30 ammo is trivial and it is in favor of the .303. 

British didn't know in 1940 that Germany would invade Russia in 1941 which is what really took the invasion of Britain off the table.


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## Peter Gunn (Mar 15, 2019)

I believe that Bell pulled a bit of a fast one, pardon the pun, when they polished up the demonstrator for the RAF, it had to be good for more than just a 2-3 MPH increase. On the P-80, polished and filled surfaces were good for a 10-11 MPH increase from SL to 20,000 for both top speed and cruising speed.

Admittedly I didn't dig out any P-39 data for polished or unpolished simply because I knew where to find the P-80 data.

P-80 Performance Tests


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## Glider (Mar 15, 2019)

P-39 Expert said:


> French/British ordered the P-400 in 1940 because they DIDN'T know that they would win the battle of Britain in the fall of that year. After they DID win the BoB they no longer needed the P-400. They didn't try to get out of paying for them until they knew that they didn't need them.
> 
> See post #442 for the weight differences.


So far there is nothing in your evidence, in fact there is no evidence at all, that the British tried to avoid paying for anything. The UK took on the entire French order for US aircraft even those they had no interest in and didn't avoid paying for anything. 
All you have is conspiracy theories that lack any fact. Timescales that are out and an aircraft that clearly didn't meet it's promised performance. I am pretty confident that any halfway decent lawyer had they wanted to would have won a case against Bell


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## P-39 Expert (Mar 15, 2019)

Shortround6 said:


> What Bell did was worth a whole lot more than 2-3mph. More like 15-20mph minimum
> 
> 
> I also have serious doubts about how much yanking the four .30 cal guns is going to do for performance.
> ...


In wwiiaircraftperformance.org there is a Memorandum at the bottom of the P-39 section titled "Speed Test, Smoothed Camouflage Finish" where they were sanded and rubbed down with pumice and water. Speed difference was 2mph at military power.

See the graph in post #442 to see the difference in performance between a 7100# P-39 and a 7850# P-39 as compared to a contemporary Spitfire V. Straight from wwiiaircraftperformance.org.


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## Shortround6 (Mar 15, 2019)

Peter Gunn said:


> I believe that Bell pulled a bit of a fast one, pardon the pun, when they polished up the demonstrator for the RAF, it had to be good for more than just a 2-3 MPH increase. On the P-80, polished and filled surfaces were good for a 10-11 MPH increase from SL to 20,000 for both top speed and cruising speed.
> 
> Admittedly I didn't dig out any P-39 data for polished or unpolished simply because I knew where to find the P-80 data.
> 
> P-80 Performance Tests



It wasn't "polished",
It had 20 coats of primer sanded between each coat. It had wood filler smoothing the metal to plexiglass (canopy ) fit/joints. It had a one piece engine cover to eliminate gaps/joints in that area. There were a few other 'tricks" employed too. 

Polishing would have been minor compared to what Bell did

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## P-39 Expert (Mar 15, 2019)

I can't resist, 20 coats of primer sanded between each coat is going to be 15mph faster than an identical plane that was sanded and polished?


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## Shortround6 (Mar 15, 2019)

P-39 Expert said:


> In wwiiaircraftperformance.org there is a Memorandum at the bottom of the P-39 section titled "Speed Test, Smoothed Camouflage Finish" where they were sanded and rubbed down with pumice and water. Speed difference was 2mph at military power.



except the Airacobra I tested at the end of April 1941 was NOT sanded/ rubbed down with pumice and water. You know it. 
See the Birch Mathews book pages 119-120. 



> See the graph in post #442 to see the difference in performance between a 7100# P-39 and a 7850# P-39 as compared to a contemporary Spitfire V. Straight from wwiiaircraftperformance.org.



yep, straight from wwiiaircraftperformance.org. except the P-39s are running at either the 5 minute rating (up until the jog in the lines to left) while the Spitfire is running at it's 30 minute rating, a nice fair comparison.......................not.


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## Shortround6 (Mar 15, 2019)

P-39 Expert said:


> I can't resist, 20 coats of primer sanded between each coat is going to be 15mph faster than an identical plane that was sanded and polished?




Rather depends on the fit an finish of the panels doesn't it? 

If 20 coats of primer (20 trips through the spray booths) isn't better than a quicky 2-3 day polish job on the top coat coat why do it?

perhaps because they are using the multiple coats of paint to seal cracks/gaps, fill in low spots (or dents) that no polish job to to the top coat ever could. 

From the book, page 120. "This treatment covered all seams, screws and rivet heads. Standard British camouflage was applied for a finish coat. This was lightly sanded to remove seams left by the edges of the camouflage templates. As a final note, the test airplane was 169 pounds lighter than a standard production model".


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## pbehn (Mar 15, 2019)

Some time around about now the discussion moves on to the Russian front (from memory)

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## CORSNING (Mar 15, 2019)

pbehn said:


> Some time around about now the discussion moves on to the Russian front (from memory)



Polished and spit-shined?......No $#!+, what the Bell direction are we going now?...

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## P-39 Expert (Mar 15, 2019)

Shortround6 said:


> except the Airacobra I tested at the end of April 1941 was NOT sanded/ rubbed down with pumice and water. You know it.
> See the Birch Mathews book pages 119-120.
> 
> 
> ...


The five minute rating was increased to 15 minutes mid 1942.

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## Glider (Mar 15, 2019)

P-39 Expert said:


> The five minute rating was increased to 15 minutes mid 1942.


Just when the Spit IX entered service, a comparison which the P39 is guaranteed to lose.

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## pbehn (Mar 15, 2019)

Glider said:


> Just when the Spit IX entered service, a comparison which the P39 is guaranteed to lose.


Same time as the Mustang MK I appeared too.


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## Glider (Mar 15, 2019)

good point


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## Shortround6 (Mar 15, 2019)

P-39 Expert said:


> The five minute rating was increased to 15 minutes mid 1942.




I think you missed the point. The Airacobras on your chart are running at 3000rpm for the first 5 minutes of their climb. The Spitfire is running at 2850 rpm instead of 3000rpm like it would do in combat. Granted the Allison didn't have a 30 min rating. It's next lower rating to military power was at 2600rpm so that wouldn't be fair either.


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## pbehn (Mar 15, 2019)

Glider said:


> good point


The Mustang Mk I blows most of the arguments out of the water, it was built and supplied to the British as a purchase and lend lease and much loved by the pilots that flew it, the engine was OK within the altitude limits known by all, the problem with the P-39 was the P-39 airframe.

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## fubar57 (Mar 15, 2019)

Ka-freakin'-boom!

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## tomo pauk (Mar 15, 2019)

pbehn said:


> The Mustang Mk I blows most of the arguments out of the water, it was built and supplied to the British as a purchase and lend lease and much loved by the pilots that flew it, the engine was OK within the altitude limits known by all, the problem with the P-39 was the P-39 airframe.



Airframe was a small part of the problem, it was less draggy than Spitfire, P-40, Re.2005 or G.55. 
Engine was the biggest part of the problem, and then we also have a problem of sticking 900 lbs worth of guns and ammo on a nominal 1150 HP engine.


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## pbehn (Mar 15, 2019)

fubar57 said:


> Ka-freakin'-boom!


I cannot possibly be the only person here that doesn't remember all these points being done to death in the past.


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## fubar57 (Mar 15, 2019)

Yep


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## pbehn (Mar 15, 2019)

tomo pauk said:


> Airframe was a small part of the problem, it was less draggy than Spitfire, P-40, Re.2005 or G.55.
> Engine was the biggest part of the problem, and then we also have a problem of sticking 900 lbs worth of guns and ammo on a nominal 1150 HP engine.


The British had a use for the Mustang Mk I and would have taken more right up to end of 1944, they had no use for the P-39. Basically the P-51 could cross the channel and get back the P-39 couldn't.


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## tomo pauk (Mar 15, 2019)

pbehn said:


> The British had a use for the Mustang Mk I and would have taken more right up to end of 1944, they had no use for the P-39.



I've never said they had use for P-39. P-39 was unsuitable for major use for ETO.



> Basically the P-51 could cross the channel and get back the P-39 couldn't.



It certainly could.


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## P-39 Expert (Mar 16, 2019)

The P-51A (MkI) and the P-39N had the same engine.

P-51A was a little cleaner so it was 10-15mph faster.

P-51A weighed about 800-1000# more so the P-39N climbed better and had a higher ceiling.

P-51A had 50% more fuel so range was a good bit farther.

P-39 probably a little more maneuverable. Easier ground handling.

Armament? Who knows. P-51A had four wing mounted .50 MGs. P-39 had center fire cannon and two synchronized .50 MGs.

One is a better interceptor, one is a better escort.

Replace the .30cal wing guns and substitute 50gal fuel in the P-39 and you have about the same plane as the P-51A.


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## Shortround6 (Mar 16, 2019)

P-39 Expert said:


> Replace the .30cal wing guns and substitute 50gal fuel in the P-39 and you have about the same plane as the P-51A.




Except you don't.

Four .30 cal guns = 99lbs
1200 rounds of 30 cal ammo= 72lbs

50 gallons of fuel weighs 300lbs
Weight of the self sealing tanks to put the fuel in???????

Wonder what the Mustang could do if you magicly took out 180lbs and added 400lbs of "stuff" with no penalty?


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## tomo pauk (Mar 16, 2019)

P-39 Expert said:


> The P-51A (MkI) and the P-39N had the same engine.



Problem being that P-51A was Mustang Mk.II, that entered service by September 1943 in MTO and CBI.
Mustang I was roughly XP-51 that is combat capable, RAF's Mustang I was in service by Spring 1942.
Mustang Ia was P-51.


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## pbehn (Mar 16, 2019)

The RAF were disappointed with the P-39 speed and pleased with the Mustang Mk1 but the difference was 10-15MPH on top speed? Where does the Spitfire figure in this?


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## tomo pauk (Mar 16, 2019)

pbehn said:


> The RAF were disappointed with the P-39 speed and pleased with the Mustang Mk1 but the difference was 10-15MPH on top speed? Where does the Spitfire figure in this?



Spitfire V was faster above ~15000 ft than P-39D, and climbed better at all altitudes. It will also out-climb the Mustang I, and probably be faster above 20000 ft.

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## Ivan1GFP (Mar 16, 2019)

drgondog said:


> Ivan the airfoil for the wing for X73 through P-51K was NAA/NACA 45-100. Only the root chord and inboard leading edge of the wing changed for the D/K.The 50 caliber guns could have been mounted vertically in A-36, P-51A/B/C but probably were angled to preserve option to install 20mm (angled) from P-51-NA to A-36. Discussions between Material Command and NAA regarding adding 20mm to P-51B and D were finally killed in November 1943 and the gun mount to 50 caliber was changed to vertical for the P-51D and Subsequent. At that time there were still on-going discussions about P-51F (interceptor- production) with Oldsmobile 20mm guns that would have imposed significant change to LE spar and aft spar for the evolving NACA 66 series wing on the future P-51F, and cancelled.



Hello Drgondog et al,
I was basing my statement on comments from a pilot who had flown both the P-51B and P-51D and noted that the handling between the two machines was noticeably different. He attributed the difference to modifications required by the gun arrangement. There certainly were some other changes after the death of Col. Hitchcock in a high speed dive but perhaps they had no real aerodynamic effect.

- Ivan.


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## Greyman (Mar 16, 2019)

From what I gather the RAF's problem with the P-39 was that it didn't work, and not how the performance shook out a few mph/fpm in whatever direction. Reading 601 Squadron's trials and tribulations with the aircraft, they went from a very experienced unit excited for their new aircraft -- to a demoralized shell of what they were.

Engine troubles and forced-landings were so constant that 'getting a four-ship section airborne became cause for celebration'. Though they gave it everything in their power, 601 Squadron wasn't able to overcome the difficulties, which were beyond what they were capable at the squadron level and what the Air Ministry were prepared to devote to the aircraft.

Conversely -- _'It is not an exaggeration to say that Soviet pilots and engineers, front-line troops and researchers, gave their maximum effort to turn the Airacobra into a fully capable combat aircraft. And in doing so they saved the Bell firm from great unpleasantness associated with the production of a series of "unfinished" aircraft.' _
(from Airacobras Enter Combat by Valeriy Romanenko ... a lot of relevent bits online at Early Cobra's in Soviet Aviation)​

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## Kevin J (Mar 16, 2019)

The Brits would certainly know from May 10th 1941 that the Germans were about to attack the USSR as that is when they picked up Rudolf Hess. They probably had a good idea perhaps 6 months before that the Germans were about to attack the USSR as they had Spitfire spy planes overflying Germany and would have detected all the troop movements which pointed away from an invasion of the UK. I can't remember when we actually warned them of an impending attack. The P-400's were heavier because they had more armour and what did they do with them, they shot up some invasion barges. Maybe that's what we needed them for in the first place, but no invasion, no P-400's required.


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## wuzak (Mar 16, 2019)

P-39 Expert said:


> Armament? Who knows. P-51A had four wing mounted .50 MGs. P-39 had center fire cannon and two synchronized .50 MGs.



Except for the P-400, the centre fire cannon was rather poor as an air-to-air weapon. And the cowl .50” hmgs fired much slower than the same gun on the P-51. Maybe half the rate?


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## Clayton Magnet (Mar 16, 2019)

The Browning action did not synchronize well, I think they were in the 400-500 RPM territory


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## Shortround6 (Mar 16, 2019)

Kevin J said:


> The P-400's were heavier because they had more armour and what did they do with them, they shot up some invasion barges. Maybe that's what we needed them for in the first place, but no invasion, no P-400's required.



They had _maybe_, repeat, _maybe_ 30-40 pounds more armor than the P-39D did. Which strangely disappeared when one was weighed for US service? (AHT Dean Page 193) 

Most new squadrons, regardless of what they intended to use them for tended to get sent on barge, coastal shipping or coastal target strikes for their first few missions. Over two years later the first P-51B mission with the 354th fighter group was a fighter sweep over Belgium and France. Meeting no German Aircraft they did some ground strafing. 
It was a way to ease a unit into combat by only keeping them in a dangerous area for a few minutes. 

By the summer of 1941 the British had little or no need of the P-39 as a barge buster. Let alone in Oct/Nov of 1941. The P-400 mounted a single 20mm with a drum feed gun for barge busting plus the two .50 cal guns. Spitfires were getting two 20mm cannon, the unloved Whirlwind had four. Beaufighters had four and they were starting to be belt feed. Four 20mm cannon for Hurricanes were in the works. (showing up the fall of 1941?). 
Until the British actually got some in England to test to they didn't realize what a dog it was at altitude. There was no quick and easy fix. They were flying a P-40 with a Merlin engine 
on June 30th 1941 about the time the P-39Cs show up in England, and even the first of these lightweight machines only manages 359mph around July 6th. You can't put a Merlin in a P-39 (not without months and months of work and there aren't enough Merlins anyway) 

This is a big part of this particular argument about the P-39, who knew what and when. Bell knew all along that it wasn't a 400mph fighter at 20,000ft or even 390mph at 15,000ft. 
They have hoped it was, they may prayed that some miracle would make it so. But they never had a test airplane in 1939-40 come close to those numbers (at least one even remotely equipped for service use.) We know that the American army didn't expect that speed and climb performance from it either or they wouldn't have signed/agreed to the contracts for the P39D with lower performance. 
So the question is when did the British know, or again, who knew when ( British test pilot and purchasing delegation in the US, British air ministry officials in England, or British pilots/squadron commanders who would have to use it) The P-39 was being touted as a 400mph airplane in ads and articles in British publications like Flight magazine during 1940. 
Granted you don't put full details (especially short comings) in a public magazine in war time but the average Briton interested in aviation in 1940 expected the P-39/P-400 to be a 400mph airplane.

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## Shortround6 (Mar 16, 2019)

Maybe they got better later but 400-500 RPM territory was where the British tested them.


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## Ivan1GFP (Mar 17, 2019)

Shortround6 said:


> Until the British actually got some in England to test to they didn't realize what a dog it was at altitude. There was no quick and easy fix. They were flying a P-40 with a Merlin engine
> on June 30th 1941 about the time the P-39Cs show up in England, and even the first of these lightweight machines only manages 359mph around July 6th. You can't put a Merlin in a P-39 (not without months and months of work and there aren't enough Merlins anyway)



Hello Shortround6,
I suspect the British had a pretty good idea what kind of altitude performance to expect from the Airacobra before they every got one. Note that although they may have ended up with a few P-40s with Merlin engines, they had been flying early Tomahawks and Kittyhawks before the Merlin versions came along. The engine in the P-39D, D-1, and F would have been almost the same as that in a P-40E.

In one of the Airacobra books (I forget which one), there was a mention of the British requirement for snow filters on the intake which caused a significant loss of performance. In addition, it was pretty common practice for US Army operators to remove the anti-backfire screens from their engines which gave a noticeable (about 1000 feet) increase in critical altitude.

- Ivan.

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## P-39 Expert (Mar 17, 2019)

Ivan1GFP said:


> Hello Shortround6,
> I suspect the British had a pretty good idea what kind of altitude performance to expect from the Airacobra before they every got one. Note that although they may have ended up with a few P-40s with Merlin engines, they had been flying early Tomahawks and Kittyhawks before the Merlin versions came along. The engine in the P-39D, D-1, and F would have been almost the same as that in a P-40E.
> 
> In one of the Airacobra books (I forget which one), there was a mention of the British requirement for snow filters on the intake which caused a significant loss of performance. In addition, it was pretty common practice for US Army operators to remove the anti-backfire screens from their engines which gave a noticeable (about 1000 feet) increase in critical altitude.
> ...


The useless backfire screens were finally discarded around the same time as the five minute rating was increased to 15 minutes, mid 1942. The 15 minute rating was for most of the combat engines including Allison and P&W.

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## P-39 Expert (Mar 17, 2019)

Shortround6 said:


> Except you don't.
> 
> Four .30 cal guns = 99lbs
> 1200 rounds of 30 cal ammo= 72lbs
> ...


For the thousandth time, delete the wing guns AND THE USELESS 100# NOSE ARMOR PLATE and substitute 50 gallons of fuel at 300#, the weight of the self sealing tanks would be mostly offset by removing the gun mounts, chargers, heaters and ammunition boxes. Very minor weight gain if any.


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## P-39 Expert (Mar 17, 2019)

Shortround6 said:


> They had _maybe_, repeat, _maybe_ 30-40 pounds more armor than the P-39D did. Which strangely disappeared when one was weighed for US service? (AHT Dean Page 193) *Armor plate/glass weighed 292# on the P-400 including the nose gearbox armor, armor for the oxygen bottles and armor just outside the rear armor glass. Delete these items (not used on other comtrmporary aircraft) and the weight of armor plate and glass is reduced to around 140#.*
> 
> Most new squadrons, regardless of what they intended to use them for tended to get sent on barge, coastal shipping or coastal target strikes for their first few missions. Over two years later the first P-51B mission with the 354th fighter group was a fighter sweep over Belgium and France. Meeting no German Aircraft they did some ground strafing.
> It was a way to ease a unit into combat by only keeping them in a dangerous area for a few minutes.
> ...


 Please see above.


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## Shortround6 (Mar 17, 2019)

The Backfire screens were there in late 1940-41 because Allison had a considerable amount of trouble with backfires during this time period. Several P-40s were lost due to engine fires (in flight, not starting up) and others suffered damage to the intake manifolds and on certain occasions parts of the cowling were loosened up enough that the airstream tore them loose. The early engines had a lightweight magnesium intake manifold that would sometimes catchfire and/or rupture with a severe backfire. 
These were replaced with a heavier, stronger aluminum manifold that went a long way towards solving some of the problems although a severe backfire could still split these. 
Changing the intake valve clearance also helped considerably (they went from 0.010 to 0.015in.) this delayed the opening of the valve slightly (very slightly but it did make a measurable difference). The British ran their Tomahawks in the dessert with the 0.015in valve clearance. 
As late as Sept/Oct 1941 the US Army materiel command was still issuing directives concerning this problem and Allison was still working on the problem.
Another thing that helped solve the problem was using sodium cooled intake valves (most engines used the sodium filled valves on the exhaust only).
On Sept 11th Wright Field ordered Allison to provide 50,400 new intake valves to retrofit the 2100 engines that had been delivered or were expected to be delivered up to Oct 1st 1941. 
These valves were to be provided at no cost under the "latent defect" clause in the contract. 

The British did not get the new valves for engines that they had already purchased, all new engines provided from this point forward under lend lease got the new valves. 

Another problem with prolonged use was that the valve clearance would change. the Intake valves would pound their seats and drive them further into head shorting the valve seat to crocker arm distance. This was also thought to be caused by the engines occasional over revving due the Curtiss electric props. The E and F engines got steel inserts in the cylinder heads for valve seats to help cure this problem. 
There was also a change in the type of spark plugs used. 

A much longer description of this is in "Vee's for Victory" pages 114 to 118.

Nobody liked the backfire screens at the time, they knew the problems they were causing with manifold pressure (which got much worse when they got clogged with dye form the fuel) but until they KNEW they had the backfire problem under control they were viewed as a necessary evil. 

Part of KNOWING was the accumulation of thousands of hours of operation with the new manifolds, new valves, new valve settings and several other measures (better venting of the engine compartment to avoid flammable vapor build up was one). 

Thinking that the early Allisons were up to the standards of the 1942/43 Allisons and only bureaucratic foolishness kept them from much greater performance is using a very rose shaded retrospectroscope. 

Things do have to viewed in perspective. The Early Allison was initially rated at 150 hours before overhaul, Perhaps not quite as good as the equivalent Merlin but certainly better than the Hispano V-12s and their Russian cousins. May well have been better than the DB601? On Feb 2 1941 Allison recommended to Wright Field that 10 engines be allowed to got to 200 hours as a test to see if all the engines could be uprated. Allison V-12s, through a series of steps (and a bunch of new parts) would reach a 400 hour time limit between overhauls (which was often exceeded on training aircraft). 

Now please note that Allison and Wright Field were still struggling to get the C-15 engine (the long nose) to where they wanted it to be as far as performance and reliability during the spring, summer and fall of 1941 when the Airacobra and P-40D/E Warhawks were starting to show up with their E and F engines. Much of what was being learned and applied to the C series engines could be applied (and was) to the later models. 

Perhaps the Army did hold onto the backfire screens too long, but until they were _sure_ the problem was _fixed_ (thousands of hours of opertainal flights) yanking them out might well have increased operational losses.

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## Shortround6 (Mar 17, 2019)

P-39 Expert said:


> For the thousandth time, delete the wing guns AND THE USELESS 100# NOSE ARMOR PLATE and substitute 50 gallons of fuel at 300#, the weight of the self sealing tanks would be mostly offset by removing the gun mounts, chargers, heaters and ammunition boxes. Very minor weight gain if any.



Please provide the weight/s for the gun mounts, chargers, heaters and ammunition boxes.

large flat fuel tanks weigh a lot more than short deep ones for the same fuel capacity. 

The bullet proofing material weighs about the same per sq ft of tank to be covered, the more sq ft you need per gallon the heavier the tank.
A rough estimate of tank weight is from page 380 of "Aircraft Power Plants" by Arthur P Fraas ( a Packard engineer) who says that plain aluminum tanks can go from 3/4 lb per gallon for small tanks to 3/8lb per gallon for large tanks of 100 gal or more. 
Bullet sealing tanks weigh between 0.7 and 1.5 lbs per gallon.

Tying to use the space where the .30 cal guns and ammo were for fuel tanks is going to result in about the worst possible shape of a tank from the standpoint of wall area to volume. 

How much weight did Bell save by getting rid of the 33 gallons in the outer fuel cells?
And you want to add 50 gallons in an even thinner part of the wing?

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## P-39 Expert (Mar 17, 2019)

Shortround6 said:


> Please provide the weight/s for the gun mounts, chargers, heaters and ammunition boxes. *No idea, but I do know that they would need to be removed if fuel tanks were replacing them.*
> 
> large flat fuel tanks weigh a lot more than short deep ones for the same fuel capacity.
> 
> ...


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## XBe02Drvr (Mar 17, 2019)

P-39 Expert said:


> delete the wing guns AND THE USELESS 100# NOSE ARMOR PLATE


And how are you going to compensate for the resulting rearward CG shift in a plane that's already borderline tail heavy? Move the battery and the radio boxes forward? Where you going to find room for them to gain back the moment arm you lost by deleting the armor? The farther the battery gets from the starter and generator, the fatter (and heavier) your cables are going to get and the more starting problems you're going to have. The farther from the CG your battery and radios are, the more G abuse they'll suffer in Air Combat Maneuvering. Tube radios located in the nose next to a 37 (or a 20) and two 50s are going to be subject to intense high frequency vibration stresses whenever you squeeze the trigger. There's more to it than just yanking the armor.
Cheers,
Wes


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## pinsog (Mar 17, 2019)

XBe02Drvr said:


> And how are you going to compensate for the resulting rearward CG shift in a plane that's already borderline tail heavy? Move the battery and the radio boxes forward? Where you going to find room for them to gain back the moment arm you lost by deleting the armor? The farther the battery gets from the starter and generator, the fatter (and heavier) your cables are going to get and the more starting problems you're going to have. The farther from the CG your battery and radios are, the more G abuse they'll suffer in Air Combat Maneuvering. Tube radios located in the nose next to a 37 (or a 20) and two 50s are going to be subject to intense high frequency vibration stresses whenever you squeeze the trigger. There's more to it than just yanking the armor.
> Cheers,
> Wes



This is the kind of stuff that most of us would never even consider that also explains why aircraft are built in certain ways. It would have never occurred to me when redesigning a WW2 fighter that they wanted the radio close to the center of the plane due to g forces (vibration from guns might have occurred to me). I’ve learned so much even when topic go way off course.

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## fubar57 (Mar 17, 2019)

https://www.defensemedianetwork.com...39-airacobra-in-the-pacific-posed-challenges/


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## Shortround6 (Mar 17, 2019)

P-39 Expert said:


> .
> *Armor plate/glass weighed 292# on the P-400 including the nose gearbox armor, armor for the oxygen bottles and armor just outside the rear armor glass. Delete these items (not used on other comtrmporary aircraft) and the weight of armor plate and glass is reduced to around 140#. Armor plate/glass weighed 292# on the P-400 including the nose gearbox armor, armor for the oxygen bottles and armor just outside the rear armor glass. Delete these items (not used on other comtrmporary aircraft) and the weight of armor plate and glass is reduced to around 140#.*



Source for the 292lbs? about 30lbs seems to have disappeared when the planes were in US service. Armor for the oxygen perhaps?

The P-39 armor never got down to 140lbs. On a P-39Q-1 it was still 193lbs.




> *The 20mm cannon in the P-400 was a non-starter with only a 60 round magazine good for 5-6 seconds firing time. It also jammed a lot. Give it the British belt fed 120 round magazine like the SpitfireV (just the logical development) and it would be a very useful gun.*



Pretty much irrelevant to the discussion at hand. Another member had suggested that Britain wanted the Airabora Is for invasion barge busting. Given the ordering of the planes before the BoB even started that seems unlikely and given the armament of the AIracobras as ordered (drum fed 20mm) they were not any better than a number of any other aircraft for this job.




> *Due to rediculously heavy weight as specified by the British. Removing the weight was a very quick and easy fix. British are comparing their 6450# Spitfire with their 7850# P-400 creation and wondering why performance is down. They knew all along. Again, please see the graph in post #388.*



You have yet to show a reference or source that says the British specified this weight. Please do so.

You can put up all the graphs you want of planes that don't really apply to the discussion at hand. A Spitfire running at less than full throttle, The P-39K with its 1325hp engine won't show up until the fall of 1942, as for the P-39C, even the USAAC wasn't dumb enough to order more than 20 of them and that was before France fell. They changed the order for the last 60 to the P-39D which weighed, surprise 7697lbs, with 104 US gallons of fuel. add another 96lbs if the internal tanks are full.



> *Bell promoted the P-400 as a 400mph airplane in '39 and '40 when it weighed 5000#, not after that. There were six weight increases under this contract between Feb 1940 and June 1941 increasing the weight from 5849# to 7635# of which the British were certainly aware since this was a direct purchase contract and they had to sign off on all changes. *



The P-39 was never a 5000lb airplane, ever. It was 'designed' for gross weight of 5500lbs, The XP-39 was changed to 5,855lbs before it was finished. when it showed up at Wright Field it weighed 6,104lbs, This was in April of 1939. It was already 10% overweight and had no guns. 

Please give list of these changes to the British contracts and source/s



> *The big test (reflecting the decreased performance) was in April '41 and the final revision to the contract increasing the order from 170 to 675 planes was signed in June. That the British were somehow tricked or fooled by Bell is rediculous. The British had the best intelligence service in WWII and had already contracted for and built a large quantity of very high performance airplanes themselves. They knew exactly what they were doing.*



You have the dates wrong or are confusing them, the British added 505 planes to the contract in May or June of 1940, not 1941. Now this may have been a letter of intent, or provisional contract or some other temporary agreement that was not finalized until June of 1941 but all parties (Bell, Allison, the USAAC, and the British) were moving forward under the assumption that the British were ordering 675 planes, that is making allocation of materials, long lead items and whose aircraft (British or American ) would be delivered (hopefully) in which months. Hundreds of extra P-39s were allocated to the British in the Spring of 1941 under lend lease and many of those were the P-39D-1s and D-2s. 

Can you give us a list of British agents ( or at least a memoir from one) doing industrial espionage in the US at this time or is this another conclusion you you have come to with no evidence to back it up?

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## Shortround6 (Mar 17, 2019)

XBe02Drvr said:


> And how are you going to compensate for the resulting rearward CG shift in a plane that's already borderline tail heavy? Move the *battery* and the radio boxes forward? Where you going to find room for them to gain back the moment arm you lost by deleting the armor? The farther the battery gets from the starter and generator, the fatter (and heavier) your cables are going to get and the more starting problems you're going to have.......... There's more to it than just yanking the armor.



The battery was already in the nose.

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## Shortround6 (Mar 17, 2019)

*No idea, but I do know that they would need to be removed if fuel tanks were replacing them.* 

So another WAGS.

*So, at one pound per gallon the new tanks would weigh 25 pounds each (for two)? The normal tanks in the P-39 weighed about 1pound per gallon. The weight would have increased by 300# of fuel and 50# of new tanks for a total of a 350# increase. Weight would have been reduced by the .30 cal guns 99#, ammo 77#, the unneeded nose and selected other armor 140#, and the gun mounts, chargers, heaters and ammo boxes. If these last items weighed 34# (8.4# per gun) then the weight penalty for the additional fuel and tanks would have been exactly zero. * 

How about actually looking up a few things before posting? the fuel system in a P-400 went about 267lbs, the one in a P-39D-2 went 291lbs so the the weight of the tanks was well over 2lbs per gallon even allowing for some heavy fuel lines and valves. 

Somewhere I thought I saw that cutting the fuel tanks (3 cells taken out of each wing) cut the empty weight by about 100lbs, I could be wrong on that but your weight estimates for the tanks seem rather low. At any rate the P-40s saved 100lbs by taking out a single 37 gallon tank which was short and fat as wing tanks go. 
You quickly jump to the low end of the range for a poorly shaped tank. 

A little though exercise, you can make a "tank" that holds 8 cubic feet of volume by making a box 2 feet on each side. 4 square feet per side, six sides is 24 sq ft.
You can also make a "tank" that holds 8 cubic ft by making a box 8 ft long, 2 feet wide and 0.5 ft deep. you now have 42 sq ft of tank wall. 
This is just to illustrate the principle. Sticking fuel tanks way out in the wings is a heavy way to store fuel. 

*I have never been in favor of less fuel for the P-39. With more than the standard 120gal the P-39's effectiveness would have been increased. The standard 120 gallons carried by the P-39 was more than was carried internally on Spitfires, 109s, (and the 190 if it's much larger engine is considered) and most Russian fighters.* 

Nobody is really in favor of less fuel, that "option" was usually forced by the need to cut weight to boost performance. 

Yes the P-39 carried more fuel, 120 gallons vs 103 for Spitfire and 106.7 for the 109. I am not going to get all excited over the P-39 because it carried 16% more fuel than standard Spitfire.


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## XBe02Drvr (Mar 17, 2019)

pinsog said:


> It would have never occurred to me when redesigning a WW2 fighter that they wanted the radio close to the center of the plane due to g forces.


Not to mention the multiplied dynamic lateral and vertical loads from abrupt maneuvering the farther these delicate electronics are from the CG.


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## XBe02Drvr (Mar 17, 2019)

Shortround6 said:


> The battery was already in the nose


Thank you, Sr6, I stand corrected. Now Cobra 'spurt, where you going to find the extra moment to make up what you lost by stripping the nose armor? Huh?
Cheers,
Wes


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## wuzak (Mar 17, 2019)

Shortround6 said:


> Yes the P-39 carried more fuel, 120 gallons vs 103 for Spitfire and 106.7 for the 109. I am not going to get all excited over the P-39 because it carried 16% more fuel than standard Spitfire.



Didn’t the standard capacity become 87USG for later models?


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## pbehn (Mar 17, 2019)

Meanwhile with the dear old Mustang/P-51 if you wanted 4 cannon you got 4 cannon, you want six 0.5 MGs you got them. More fuel? in the back or under the wings where would sir prefer? You may need some more oil Sir, we can sort that out for you too. Removing fuel, armour guns and other military equipment to increase performance is just trending away from being a military machine and towards a Reno racer.

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## Jugman (Mar 17, 2019)

wuzak said:


> Didn’t the standard capacity become 87USG for later models?



The P-39N through P-39Q-1 had a max internal capacity of 87USG. There were kits made to bring them back up to normal capacity.


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## Shortround6 (Mar 17, 2019)

The radio/s were in the rear of the airplane.





The CG is right about the back of the door or just under the very back of the pilots seat/over the wing ammo boxes.




Fuel system. It is just a drawing and may not be accurate but the fuel cells appear to taper. They seem to be shorter and thinner the further out you go from the fuselage.
going further out into ever thinner parts of the wing is just making the volume to surface area ratio worse.

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## Greyman (Mar 17, 2019)

Fighter Command looked into the issue of Airacobra armour 30 September, 1941:

_It does not appear at present that armour can be deleted although this aircraft appears to be carrying a considerable amount._
_
One governing factor against addition or deletion of weight is the position of the Centre of Gravity. The front of the aircraft is heavily armoured, but removal of this would result in the necessity for returning the C.G. to safe limits by the use of ballast and, as the majority of the weight is already in the nose, the saving in all-up weight would be negligible. The reduction gear is heavily armoured, but it would appear unwise to reduce this protection since, apart from the above considerations, damage to the gear might well result in the engine extension shaft whipping violently, and causing the aircraft to break up. The two oxygen bottles in the nose have armour protection and these might be deleted if wire-wound bottles were used. Rear armour for the oil and coolant tanks is the minimum that can be accepted. No additional armour can be added to the rear without forward ballast to correct the CG position, with the resulting loss in performance. 

It is not recommended that any alterations to the existing armour be made.
_

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## Greg Boeser (Mar 17, 2019)

Can't comment on P-39 fuel tanks, but a comparison of B-26 bomb bay tanks yields 178 pounds for an aluminum, 354 lbs for a self sealing tank of the same capacity. 
So that's about double the weight.


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## Shortround6 (Mar 17, 2019)

An awful lot has to do with the size and shape of the tank.

AHT says a P-47D with the 305 gallon set up had a 332lb fuel system
A P-47D-25 with the 370 gallon set up had a 422lb system. 
A P-38J with a 400 gallon set up had a 506lb system.
A P-51B/C with the 180 gallon wing tanks had a 320 gallon fuel system
Putting in the 85 gallon rear tank added 255lbs, how much of that was brackets, piping and relocating other components I don't know. 

All these weights include piping and valves, some may include pumps of some sort.


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## Greyman (Mar 17, 2019)

Found some specific info on armour.

P-400 had 291.28 pounds of armour.

P-39D-2 differed in the following respects:
- no forward O2 bottle plate (*-35.01 lb*)​- no aft O2 bottle plate (*-27.60 lb*)​- different cabin armour plate (10.91 lb instead of 11.20 lb) *-.29 lb*​- different forward armoured glass (21.72 lb instead of 15.66 lb) *+6.06 lb*​- different bulkhead armour plate (*same weight*)​- different turnover bulkhead plate (14.90 lb instead of 19.12 lb) *-4.22 lb*​- different aft armoured glass (44.17 lb instead of 48.94 lb) *-4.77 lb*​- body turnover armour plate added (*+12.81 lb*)​- different main oil tank armour (*same weight*)​​Overall P-39D-2 drops *53.02 lb* in armour.


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## Shortround6 (Mar 17, 2019)

Thank you,

So we may assume (with all that entails) that the British specified the armor around the oxygen tank/s ?

Was there a difference in the oxygen systems that the British felt that they needed such protection? 
AHT says the US P-39s used a low pressure system with 1 to 4 bottles while the P-400 export version got a higher pressure system.

Was the British system (or high pressure system) particularly vulnerable to gun fire?
Bottles exploded when hit or ruptured violently?


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## XBe02Drvr (Mar 17, 2019)

Shortround6 said:


> Thank you,
> 
> So we may assume (with all that entails) that the British specified the armor around the oxygen tank/s ?
> 
> ...


A low pressure system uses gaseous oxygen compressed, but doesn't have all that much total quantity in any one bottle.
A high pressure system is likely to be more vulnerable, as the stress on the bottle is much higher, making the likelihood of rupture greater in the case of a bullet or shrapnel strike, and the quantity of liberated gas is so much greater as to create a locally oxygen-rich environment with attendant combustion opportunities. Ever drop a handful of iron filings into a beaker of pure oxygen? Try it sometime.
Cheers,
Wes


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## P-39 Expert (Mar 18, 2019)

Greyman said:


> Found some specific info on armour.
> 
> P-400 had 291.28 pounds of armour.
> 
> ...


So, the AAF thought the Brits had included too much armor, right? Now drop the nose armor to save another 100#.


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## Ascent (Mar 18, 2019)

P-39 Expert said:


> So, the AAF thought the Brits had included too much armor, right? Now drop the nose armor to save another 100#.


It's already been explained that you can't drop the armour in the nose without shifting the CoG dangerously unless you add ballast which totally negates the reason for dropping it.

By all accounts the P39 was marginal on CoG already.


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## P-39 Expert (Mar 18, 2019)

Ascent said:


> It's already been explained that you can't drop the armour in the nose without shifting the CoG dangerously unless you add ballast which totally negates the reason for dropping it.
> 
> By all accounts the P39 was marginal on CoG already.


Nothing has been proven. Just move the radios up from the tail cone to behind the pilot/above the engine. Radios located here in lots of photos. Should actually improve handling since weight has been relocated closer to the CG.


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## P-39 Expert (Mar 18, 2019)

XBe02Drvr said:


> And how are you going to compensate for the resulting rearward CG shift in a plane that's already borderline tail heavy? Move the battery and the radio boxes forward? Where you going to find room for them to gain back the moment arm you lost by deleting the armor? The farther the battery gets from the starter and generator, the fatter (and heavier) your cables are going to get and the more starting problems you're going to have. The farther from the CG your battery and radios are, the more G abuse they'll suffer in Air Combat Maneuvering. Tube radios located in the nose next to a 37 (or a 20) and two 50s are going to be subject to intense high frequency vibration stresses whenever you squeeze the trigger. There's more to it than just yanking the armor.
> Cheers,
> Wes


Just move the radios from the tail cone up above the engine right behind the pilot. Lots of original photos show the radios located here. Moves weight closer to the CG, should help maneuverability.


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## Shortround6 (Mar 18, 2019)

P-39 Expert said:


> So, the AAF thought the Brits had included too much armor, right? Now drop the nose armor to save another 100#.


 How do you get that?

The Americans used a different oxygen system that didn't require bullet proofing. The Americans removed 62.61 lbs of armor from the the oxygen set up and yet the total armor weight difference was only 53.02 lbs. so the Americans, with a bit of juggling the other pieces, were using 9.6lb more than the British once the armor for the oxygen tanks is taken out. 


As to the radios, the radios changed between the different types/models and between countries. The British may have started fitting IFF gear before other countries. One diagram of a P-39 Q shows radios both in the original position and above the the engine but doesn't say what kind of radios they are. IFF gear tends to get lumped in with radios instead of being called a radar transponder. 

From AHT just to show how confusing things are.

Category,,,,,,,,,......................,,,...P-39D..........P-39D-2............P-400
Elec system.................................225..................274.6.................278
communications........................62.....................80.2..................35
Misc. Eqpt (radio)......................----................129.2...............109.9

what piece of equipment got thrown into which catagory changed over time. I am not sure about the lack of radio weight for the P-39D. radio was not counted in basic weight? sample aircraft did not have radio fitted? I have no idea what "communications" covered if the radio weights are listed elsewhere. 
The roughly 50lb increase in electrical weight is interesting. It cover quite a few things.
Voltage requirements for different pieces of equipment varied and things like this were used to convert it.




What catagory this goes in (electrical or radio) I have no idea. 
people have already said that the old radios could be tempermental. 
Some of us are old enough to remember even car radios being affected by poor ignition wires on car engines. Shielding the radios from static from the ignition system or other electric devices in the plane took some doing. They got a lot better at it fairly quickly but again, just because they could do something in 1943 doesn't mean they could do it in 1941. 
Sometimes "the" radio was in one box, often you had a radio tray or box that contained several separate pieces of equipment or chassis. Sometimes descriptions, especially if translated are not real clear on exactly what was done. 

Before you get too crazy about removing the nose armor please remember that when they went from the P-39C to the D/P-400 they also yanked about 50lbs of .30 cal guns and about 60lbs worth of ammo out of the nose. Plus accessories. 

Larry Bell and company did build one really stripped aircraft which I have already mentioned but there doesn't seem to be record of it's CG location. And it was flown by how many pilots? a few company test pilots? 
What is acceptable flight behavior with an aft CG location varies from country to country. Or even in the same country depending on how severe the combat situation is. 
Just because the Russians thought an airplane was OK to fly doesn't mean the UK or the US would.

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## Shortround6 (Mar 18, 2019)

XBe02Drvr said:


> A low pressure system uses gaseous oxygen compressed, but doesn't have all that much total quantity in any one bottle.
> A high pressure system is likely to be more vulnerable, as the stress on the bottle is much higher, making the likelihood of rupture greater in the case of a bullet or shrapnel strike, and the quantity of liberated gas is so much greater as to create a locally oxygen-rich environment with attendant combustion opportunities. Ever drop a handful of iron filings into a beaker of pure oxygen? Try it sometime.
> Cheers,
> Wes


 
I will take your word.

I was one of the SCBA bottle fillers on my shift at the fire dept. Granted this was quite a number of years after WW II but the bottles (1980 psi when I started) were ALWAYS filled when they were contained in a heavy steel cylinder (with lid) bolted to the floor. Later on we got a new compressor/filling station that held 3 bottles in heavy steel cylinders but the air valves wouldn't open until the heavy sheet metal doors were closed which rotated the cylinders to a vertical position. We never had an accident but highly compressed gases are nothing to fool with.

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## XBe02Drvr (Mar 18, 2019)

Shortround6 said:


> We never had an accident but highly compressed gases are nothing to fool with.


Back in the '60s in upstate NY, a boat on the way to a dive site had a SCUBA tank, that was foolishly left standing up on a seat, fall over and bang it's old style tall thin valve assembly against another tank lying on the deck. The valve head snapped and the tank launched itself into the air and PENETRATED the vertical web of an I beam under a bridge the boat was approaching. The valve assembly ricocheted, bounced off the PFD of the boat's driver, and shot over the side. Nothing to fool with, for sure.
Back in the day dive shops used to fill tanks submerged in a water bath filled right to the overflow tube. A beaker under the overflow caught the water displaced by the tank's expansion as it took on 2,200 PSI of air. If the overflow exceeded the specified number of CCs, the tank had to be removed from service and sent off for hydrostat testing.
Cheers,
Wes


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## Ivan1GFP (Mar 18, 2019)

Here is a pretty good reference for the weights and locations of the armour on various models of the Airacobra.

Shortround6, you made a comment that the CoG of the Airacobra was at the back of the pilot's seat and about even with the rear edge of the door.
Do you happen to know what fuselage station this would be?
I have tried working backwards from the CoG locations, loaded weights and moments from a P-39Q Loading Diagram from the manual but am quite convinced that this is not reflective of the CoG of the early Airacobra. I suspect that the CoG was at least a couple inches further back.

- Ivan.

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## Shortround6 (Mar 18, 2019)

First, thank you very much for this chart.

I don't have the frame number, a drawing for the CG of a P-39Q is in page 21 of this manual.

https://ww2aircraft.net/forum/attachments/p-39q-pdf.33643/

Hope this helps
it may be the one you have.

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## P-39 Expert (Mar 18, 2019)

Regarding the nose armor, Daniel Whitney in "Vees for Victory" stated that the P-39M no longer needed the nose armor for ballast, which was it's primary purpose, and no personnel had ever seen a P-39 hit in that area. But, the nose armor was still included in the P-39M (and N/Q).


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## Shortround6 (Mar 18, 2019)

Now here we have an author's account conflicting with parts charts. 
We also have Mr Whitley saying " Many _Airacobras_ that had been shot down in combat had been lost because of one bullet penetrating the engine manifold, carburetor, or cam-shaft covers. The Objective was to provide maximum armor protection for these vital areas. In order to achieve a weight reduction a great number of more-or-less useful, but not necessary items were removed from the aircraft." he goes on to say that the gear box armor was removed and like you say the field reps had not seen any bullet strikes there. 
Then " The first of these aircraft, a P-39M-1, became known at Bell as "old Ironsides"" 

Which hardly sounds like they reduced the armor, and according to the chart above the P-39M "old ironsides" unless it was a one off special, used exactly the same armor as the P-39K & L and the N & Q. No more and no less. 

On many of these later P-39s (after the D and F) there were a variety of propellers (not all the same weight) different reduction gears, and the engines were not all the same weight. The Later ones got a bit heavier perhaps only 10-20 pounds. I don't know if there were differences in the accessories. Starters, generators and such (no hydraulic pump). The engine does not sit on the CG, the nose of the engine (where the reduction gear would be on a normal engine) sits on the CG with the engine actually behind the CG. 

They may have intended to take out the nose armor but changed their minds? 

On plane that is not supposed to be flown without ammo for nose guns unless it is carry ballast to compensate for the weight, taking 70-95lbs out of the plane 3-4 feet further forward seems like skating on a very thin edge.

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## Glider (Mar 18, 2019)

I note that 601 Squadron immediately recognised six key issues that had to be addressed immediately, the fifth one people may find interesting in view of the comments about moving equipment within the aircraft:-

a) Introduction of a master valve so the oxygen could be switched on in the cockpit
b) Modification of the gun sight 'so the pilot could see out of the front of the aircraft'
c) Changes to the wing ammunition tanks as they quickly became distorted and jammed.
d) Modifications to the harness release mechanism
e) Removal of the IFF from behind the pilot as it badly obstructed the view aft
f) Introduction of a throttle control friction dampner

There were a host of other issues as they were crated stright off the production line without testing


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## Shortround6 (Mar 18, 2019)

OoooKaaay.
Fit one of the first "bubble' canopies on a fighter and then fill the back of the bubble with "stuff" so you can't see out of it


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## P-39 Expert (Mar 18, 2019)

Shortround6 said:


> Source for the 292lbs? about 30lbs seems to have disappeared when the planes were in US service. Armor for the oxygen perhaps?
> 
> The P-39 armor never got down to 140lbs. On a P-39Q-1 it was still 193lbs.
> 
> ...


Birch Matthews in "Cobra! Bell Aircraft Corporation 1934-1946" is very specific that the final revision (and increase) to the contract was in June *1941* after testing the P-400 in April.


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## Ivan1GFP (Mar 18, 2019)

Thanks Shortround6,
That P-39Q manual is the same one I was using for calculations and, as I commented earlier, I suspect that its numbers do not really reflect the CoG issues of the earlier Airacobra we are discussing here.

Since you already provided a link to the manual, I won't repost the data from the diagram and chart listing the weights and moment arms of the equipment.
Early last year, I took the numbers from the chart and entered them into a spreadsheet so that I could see what would happen under various load conditions and what MIGHT happen if the loads were varied a bit in location.

The "Arm" for each item of equipment appears to be the offset from the Fuselage Horizontal Reference Line - Station Zero.
From dimensional drawings of the Airacobra, it can be seen that:
Wing Root Leading Edge is at Station 106.15 inch
LE Wing Root to LE MAC is 5.41 inch, therefore LE MAC is at Station 111.56 inch.
MAC is 80.64 inch.

From this, it can be calculated that with aircraft in empty equipped (Basic Weight) condition, CoG is at 30.16% MAC.
In Loaded condition, CoG is at 28.1% MAC.
Both of these numbers are quite ordinary.
Note that these numbers are calculated with the Landing Gear UP which would be the expected configuration for maneuvering.
Gear Down would shift the CoG very slightly forward and improve stability.

Assuming the Basic Weight is the low limit of the aircraft weight in the air, then it can be seen that Fuel load has a pretty negligible effect on CoG. It is less than two inches ahead of the CoG.
The Wing Armament is also very close to the longitudinal CoG (about 3 inches ahead) so whether the normal load of 300 rounds per gun or maximum load of 1000 rounds per gun was carried would not affect CoG very much.

The 37 mm cannon ammunition is pretty far forward but there is only 60 pounds of weight for 30 rounds which was typical load from the P-39D onwards. (The P-39C only carried 15 rounds.)

The .50 Cal cowl MG ammunition was typically 200 rounds and for the P-39Q would weigh 124 pounds. Expending this ammunition would have the greatest effect on aircraft trim.
Now here is where life gets interesting.
Most sources I have found list the ammunition capacity as 200 rounds per gun.
Some of the aircraft tests from WW2 Aircraft Performance site list the aircraft as carrying 250 (!) rounds.
The Russian Airacobra manual which can be found on our site lists the ammunition capacity as 270 rounds per gun.

This extra ammunition might be one factor that made CoG issues less of a problem when the Soviets flew the Airacobra.

- Ivan.

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## Ivan1GFP (Mar 18, 2019)

Shortround6 said:


> OoooKaaay.
> Fit one of the first "bubble' canopies on a fighter and then fill the back of the bubble with "stuff" so you can't see out of it



Hello Shortround6,
Before coming to that conclusion, it might be worthwhile to look over some photographs of the Airacobra.
The Airacobra Pilot sits relatively high in the cockpit which can be seen in numerous photographs and videos.
It was a fairly small cockpit. The typical pilot sat with his eyes very nearly at the level of the top of the window in the door.
At that angle, one can cram in quite a bit of stuff behind the cockpit in the little deck area above the engine and not obscure any vision at all.
Also keep in mind that on some of the later models of the Airacobra, the geniuses of design decided to replace the slab of armour glass behind the pilot with a piece of nice opaque metal armour, so it would not make a difference anyway.

- Ivan.


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## Shortround6 (Mar 18, 2019)

P-39 Expert said:


> Birch Matthews in "Cobra! Bell Aircraft Corporation 1934-1946" is very specific that the final revision (and increase) to the contract was in June *1941* after testing the P-400 in April.



You are correct, that is what is printed it the book. However it makes no sense, especially for your theory that the British deliberately specified a plane that was too heavy so they could get out of the contract.

The French ordered, or expressed an intent/opened,
negations for 165 planes in the fall of 1939, there is a provision in the contract that should France fall or otherwise default Britain will take over the contract. The deal is not signed until April 10th 1940 Larry Bell returns to Buffalo with a 2 million dollar check, quite possibly saving the company from bankruptcy.

In June France falls and Britain takes over the contract. Here is where the narratives start to diverge. Narrative A says the British increased the total number of aircraft to 170 (some people say it was already 170 but 5 aircraft aren't that big a deal) and that 170 on order would remain the number of the contract until the following year.
Narrative B says that after France fell Britain not only took over the contract (as it was obligated to do) but ordered an additional 505 aircraft. 

for both Narratives the US Army orders about 389-394 additional P-39Ds to go with the original 60 on order.

Narative B says that Bell had about 1600 aircraft on order worth 60 million as of Jan 1941. Numbers from either narrative don't line up with this.
Dec 1940 is When Churchill tells Roosevelt that Britain is effectively broke and cannot pay for any more supplies. According to Narrative A the British only have 170 aircraft on order at this time. 
March 11th is when the lend lease bill is passed/signed and Britain no longer has to pay for supplies. 

The P-400/Airacobra performance trial with the Special is flown at the end of April. 

Narrative A has the British signing a contract for the 505 P-400s on June 20th 1941 and paying for them cash. No narative says these were lend lease aircraft. 

Narrative B has the British, on June 11th of 1941 ordering 494 P-39D-1 aircraft and P-39D-2 aircraft under lend lease.(not all may have been built).

So we have several major discrepancies. 
For the theory that the British deliberately specced the P-400 to be too heavy, Narrative A really doesn't look good as they had only paid for 170 planes (or were obligated to pay for). If they wanted to save money just don't order the 505 extra planes in June of 1941. Germans are helping the Italians in Yugoslavia and Greece. They started sending a few small units to North Africa in Feb. They would attack the Soviet Union on June 22 so one can assume that the British had pretty well written off the possibility of the Germans invading anytime soon (many, but not all, of the barges had returned to normal commercial traffic). 
It would also have to assume that the British had decided they didn't even want the ex French aircraft if they were changing the specs with the intent to get out of the contract in the fall of 1940 when German intentions/capabilities were not so clear cut. 
In August of 1941 the USAAC ordered 1800 P-39G/model 26s. These would become P-39K,L and Ms. 

For the British to load up the the P-400 so it won't meet the performance specifications the British have to know that lend lease is a done deal (end of February at the soonest?) .
They have to have a lot more than the original 170 on order. and it has to be done in a few months so they can pocket the cash and replace the canceled planes with lend lease ones. 

What happened is that the British took all of the original 170 plus around another 42 or more, Shipped a bunch to russia and gave the rest back to the US and also either sent the lend lease planes to Russia or let the US take them over.

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## Greyman (Mar 19, 2019)

Shortround6 said:


> Thank you,
> 
> So we may assume (with all that entails) that the British specified the armor around the oxygen tank/s ?
> 
> ...



Not sure who specified it. Might have been a British, French or US addition.

I'd note Fighter Command had said "_The two oxygen bottles in the nose have armour protection and these might be deleted if wire-wound bottles were used._" Perhaps safer O2 bottles were used in later variants when the armour was deleted.

One thing I've noticed is that the British don't seem to have made mention of the 'tumble' problem that the VVS and USAAF had -- and the British only dealt with the version with that forward O2 armour ...

Bottles can explode when hit, though it seems to heavily depend on where they are hit. I have a good chunk of information on this subject but I haven't gone through it. I know George Beurling specifically mentioned he tried to hit enemy aircraft in the O2 bottles.

Check out this Wellington that had a bottle struck by a 20-mm.


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## Shortround6 (Mar 19, 2019)

Thank you. 
as mentioned before the US used a low pressure system with a different regulator.
Perhaps the US bottles didn't rupture as badly when hit???
Or like you say, later bottles were of heavier construction and didn't need armor (although the heavier bottle/s would eat up some of the savings on armor)


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## P-39 Expert (Mar 20, 2019)

Ivan1GFP said:


> Thanks Shortround6,
> That P-39Q manual is the same one I was using for calculations and, as I commented earlier, I suspect that its numbers do not really reflect the CoG issues of the earlier Airacobra we are discussing here.
> 
> Since you already provided a link to the manual, I won't repost the data from the diagram and chart listing the weights and moment arms of the equipment.
> ...


Excellent analysis. Any idea how much the brass weighed on the ammunition, because it was held inside the armament bay after firing instead of being ejected overboard.


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## Shortround6 (Mar 20, 2019)

The empty primed case weighed up to about 880 grains/57 grams (about 0.125lbs) there was tolerance of -50 grains which we can ignore here. 

So the plane kept about 50lbs of brass inside with all the .50 cal ammo fired (for 200rpg), plus the weight of the links.

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## P-39 Expert (Mar 20, 2019)

Shortround6 said:


> You are correct, that is what is printed it the book. However it makes no sense, especially for your theory that the British deliberately specified a plane that was too heavy so they could get out of the contract.
> 
> The French ordered, or expressed an intent/opened,
> negations for 165 planes in the fall of 1939, there is a provision in the contract that should France fall or otherwise default Britain will take over the contract. The deal is not signed until April 10th 1940 Larry Bell returns to Buffalo with a 2 million dollar check, quite possibly saving the company from bankruptcy.
> ...


Big question I always had is, how in the world did the British think the P-400 would be competitive (achieve the performance guarantees) at 7850# when the SpitfireV weighed 6450# and had a more powerful engine? The whole exercise seems doomed from the start. The planes did get built, they sure got used by the AAF and the Russians, and Bell got the $2million advance which probably saved them financially, but the rest of that procurement exercise was crazy.


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## P-39 Expert (Mar 20, 2019)

Shortround6 said:


> The empty primed case weighed up to about 880 grains/57 grams (about 0.125lbs) there was tolerance of -50 grains which we can ignore here.
> 
> So the plane kept about 50lbs of brass inside with all the .50 cal ammo fired (for 200rpg), plus the weight of the links.


Then a little more for the 37mm cases.


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## Shortround6 (Mar 20, 2019)

P-39 Expert said:


> Big question I always had is, how in the world did the British think the P-400 would be competitive (achieve the performance guarantees) at 7850# when the SpitfireV weighed 6450# and had a more powerful engine? The whole exercise seems doomed from the start. The planes did get built, they sure got used by the AAF and the Russians, and Bell got the $2million advance which probably saved them financially, but the rest of that procurement exercise was crazy.



The process was crazy, but it is what can happen when you have a new and inexperienced company trying out novel concepts/ideas. 
Mix in the French, with their inclination to the weird and wonderful in engineering, and then British, who seem to have been along for the ride. The only prople who seem to have any real handle on things was the USAAC, who did change their contracts. 

Some of the 'steps' as laid out in Birch Mathews book look a bit strange.

Date..........................empty.....................useful load.......................gross......................remarks
Feb 1940.................4,524...........................1,325..............................5,849......................1-cannon, 2 machine guns (1)
Mar 1940................4,715...........................1,285..............................6,000.......................2 machine guns added to each wing (2)
May 1940...............5,139...........................1,841..............................7,000.......................wing gun caliber increased (3)
Jul 1940..................5,383............................1,974..............................7,350.......................armor and self sealing tanks added (4)
Jan 1941.................5,406............................2,060..............................7,466.......................minor empty and useful load changes
Jun 1941.................5,548............................2,087.............................7,655.......................Engine and fixed equipment weight changes
Jul 1941...................5,550...........................2,087..............................7,637.......................Actual weight of Serial number AH 621

Which is very pretty but leaves out a lot and/or makes no sense. 

The XP-39 weighed 4,545lbs empty, had a 1,559lb useful load and grossed 6,104 lbs. Yes in had the weight of the turbo installation but it also had no guns. 

Some sources say the XP-39B (same airframe, turbo removed and other details changed) grossed around 5845lbs. this was the ONLY p-39 airframe in existence in the fall/winter of 1939/40. it also had no guns. See:

Note (1) how they expected to add even a 20mm cannon (around 160lbs with full drum of ammo) and two 12.7/13mm machine guns (another 260lbs) and NOT increase the gross weight is beyond me. 

Note (2) more confusion. Empty weight does NOT include the weight of the guns (that would be _empty equipped_). Now perhaps the increase in "empty" weight covers the gun mounts/braces, gun servicing doors and some other details? but you just added 80-100lb of gun weight to the useful load (and at least 70lbs of ammo weight at 300rpg) while cutting the useful load by 40lbs. 
Interesting factoid here, Useful load of a MK I Spitfire with a fixed pitch prop was 1337lbs. Guns, ammo, fuel, oil, radio, pilot&parachute. Seeing a problem with useful load of the French P-400 here????

Note (3) and an increase in empty weight of 444lbs but empty weight does not include the weight of the guns. Blaming any meaningful weight difference on changing the gun caliber from 7.5mm to 7.7mm is bogus. Increasing the useful load by 1000lbs so you can actually carry the guns, ammo, pilot and fuel at the same time is understandable. but there is where the performance starts to go to pot. How much of this was being communicated to the British I have no Idea (or if claims of an improved Allison with more power would restore performance?) 
Please note that the YP-39s being delivered in the late fall and winter of 1940 had 1090hp V-1710-37 engines and not the 1150hp V-1710-35 of later Airacobras. 

Note (4) we finally get close to reality, the empty weight goes up 194lbs (which doesn't quite cover the weight of the self sealing tanks which would be included in empty weight and useful load (which would include armor) goes up 133lbs. but they may have traded off fuel to cover the rest of the weight difference?


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## P-39 Expert (Mar 20, 2019)

*I told you those wing guns were heavy.  *

I couldn't reconcile those numbers either. But at the end of the day the P-39 could have easily weighed 5400# empty (with self sealing tanks) and 7100# gross (with armor plate/glass). A very different plane performance wise.


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## Ivan1GFP (Mar 20, 2019)

P-39 Expert said:


> Big question I always had is, how in the world did the British think the P-400 would be competitive (achieve the performance guarantees) at 7850# when the SpitfireV weighed 6450# and had a more powerful engine? The whole exercise seems doomed from the start. The planes did get built, they sure got used by the AAF and the Russians, and Bell got the $2million advance which probably saved them financially, but the rest of that procurement exercise was crazy.



Hello P-39 Expert,
There was a lot of "Crazy" going on at that time if you think about it.
In April 1940, the British were willing to contract with North American to build an entirely new fighter that didn't even exist as a paper design. This was early in the Battle of Britain and the outcome wasn't so sure. The fact that things turned out pretty well is a nice story but from the British viewpoint, there wasn't any way they could predict things would go so well.

As for getting decent performance at 7850 pounds with a 1150 HP engine, that sounds very much like what that new fighter design achieved. The Airacobra is a very slick design and LOOKS like it should be very fast. There was plenty of advertising hype at the time that claimed it was a 400 MPH fighter. There were articles in a few aviation magazines and even one in Popular Mechanics.

My own belief is that this argument about the increased gross weight of the Airacobra isn't really getting at the real cause of the issue.
From what I have seen in test reports, a weight increase doesn't usually affect the maximum speed of an aircraft very much.
While there IS an effect, it tends to be small, perhaps 2-5 MPH in the typical case.
In the case of the Airacobra, the difference between P-39C and British spec Airacobra is 15-20 MPH: 350+ MPH versus around 370 MPH. Something else is going on besides a weight increase.
Weight increases affect Climb Rate and Service Ceiling to a much greater extent.

My belief is that the place to look is at the changes to the engine configuration and perhaps operating parameters that may have reduced power or critical altitude. The backfire screens as an intake obstruction would have had some effect. The snow screens that were on the British Airacobra were only on their aircraft and it appears that although the maximum engine output was not decreased, the aircraft's critical altitude was reduced to about 11,000 feet which is 2000 feet below similar aircraft without either of those obstructions in place.
A couple of the US tests also show that the pilot was using manual mixture control and getting another 3 MPH and 25 HP over the typical "Auto-Rich" setting. Can this be taken as a representative test result? Would the British test pilot have done something similar?

- Ivan.


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## P-39 Expert (Mar 21, 2019)

The gross weight was extremely important for the P-39/400 because it affected the climb/ceiling much more than the speed. A weight savings of 100# only increased speed about 1mph. A weight savings of 100# increased climb rate about 120fpm. As you can see if the weight savings was 800# (7850-7050) speed would only increase about 8mph (not significant), but the rate of climb would increase about 1000fpm (very significant). Add 1000fpm to the nominal climb rate of 2700fpm and you have a very fast climbing plane.

More importantly less weight increases ceiling as well as climb rate. A planes "combat" ceiling was the altitude at which the plane could no longer climb at at least 1000fpm. Rate of climb normally decreases with altitude so once the "combat" ceiling was reached rate of climb slowed gradually above that altitude reaching the absolute ceiling when climb rate is zero. The P-400 with the ubiquitous drop tank's combat ceiling was around 18000'. The Japanese bombers and fighters flew well above that altitude, bombers coming in at between 18000' and 22000', sometimes a little higher. A combat ceiling of 18000' means that while you can then climb up to 22000' it is a long, slow and laborious process that is hard on your engine (at full power) and exposes you to opposing fighters that can climb faster. Not much fun, at all. This is what the term "low altitude fighter" means. With drop tank you have a real hard time getting up to where the opposition is. The ultimate disadvantage. See the graph in post #388.

But at 7100# the P-39/400 with drop tank would have a "combat" ceiling of about 23000' at normal power and 31000' at full power after the drop tank is dropped. So you could easily climb at normal power with drop tank up to 23000' and patrol for incoming bombers. When bombers are sighted the drop tank is jettisoned and you can climb up to 31000' before reaching "combat" ceiling. Since not much combat occurred above 26000' you had plenty of climb to handle pretty much any situation. And that rate of climb will be better than any opponent at all altitudes in '41-'42. Huge advantage. P-39-P/400 is now a high altitude plane.

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## Ivan1GFP (Mar 21, 2019)

Hello P-39 Expert,

First of all, it seems to me that the main complaint about the Airacobra was that its speed was too low. British testing put it at just over 350 MPH while the original expectation was a 400 MPH fighter. Note that when the Mustang came along, it was doing about 380 MPH but didn't climb any better because its engine power was identical and it was about as heavy or even more so and, yet the British didn't have problems with it and continued operating the ones they had until the end of the war while they got rid of the Airacobra.

Since we seem to also be discussion Airacobra versus Japanese aircraft:
For initial climb rate, the P-39D tests show 2720 fpm which is almost identical to the 2750 fpm climb rate achieved in testing the Aleutian A6M2. The critical altitude of the P-39D without backfire screens is about 13,000 feet. The critical altitude of the A6M2 according to their manual is 4200 Meters or 13,780 feet. (Pretty close, huh?) So there should not be much of a difference., right?
Both aircraft had single speed single stage superchargers.

You keep commenting on how there was a great weight difference between the P-39D and P-400.
I have attached a table with the values I believe to be correct for both aircraft. I collected the data early last year when I was working on a project involving a P-39D/F. I believe most of the data came from America's Hundred Thousand.
I added a "Normal Loaded Weight" column this morning with the partial ammunition and fuel loads in that configuration.
Engine Oil weight should also be reduced a bit also but I do not have the numbers handy to do that and I do not see that it would make any substantial difference. The weights of the two aircraft seem to be very close to me.
Can you explain why my numbers are wrong and why you believe that the weights really should be 7100 versus 7800 pounds?
Other than "Miscellaneous Equipment", I do not see anything that can not be explained pretty easily.

- Ivan.


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## wuzak (Mar 21, 2019)

Why are the cowl guns heavier on the P-39D than the P-400 or P-39D-2?

And why is the P-400's pilot heavier?

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## P-39 Expert (Mar 21, 2019)

Thanks Ivan,

Main complaint from the British was speed because it was below the contract guarantee. Actually it was about the same as their Spitfire V, faster below 18000' and not more than 10mph slower above. P-39 vs Allison Mustang: Mustang weighs 8400-8600#, will always be outclimbed by a P-39 at 7650#. Mustang was faster by 10-15mph.

A standard P-39 at 3000rpm would climb with a contemporary Zero for five minutes, then the P-39 had to throttle back to normal power for the remainder of the climb. That's when the Zero "walked away" from the P-39. The five minute military power limit was increased to 15 minutes in mid '42, after that it should climb with a Zero all the way up.

I hope I didn't confuse you, I was comparing the weights of the P-39/400 (about the same) with the P-39*C *which weighed 7100#. It's just a way to compare performance based on weight since the P-39/400 had the same aerodynamics, engine and propeller, just different weights.


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## Greyman (Mar 21, 2019)

I really don't think the issue was speed. The RAF used Hurricanes, Mohawks, Tomahawks, Kittyhawks, and Whirlwinds for months if not years after kicking the Airacobra to the curb. The Airacobra was as fast or faster than all of these aircraft. 

The aircraft wasn't finished, didn't work (as 601 Squadron and the VVS pointed out), and to bring it to an acceptable level required more effort than the RAF was willing to put up with.

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## Glider (Mar 21, 2019)

P-39 Expert said:


> Thanks Ivan,
> 
> A standard P-39 at 3000rpm would climb with a contemporary Zero for five minutes, then the P-39 had to throttle back to normal power for the remainder of the climb. That's when the Zero "walked away" from the P-39. The five minute military power limit was increased to 15 minutes in mid '42, after that it should climb with a Zero all the way up.


While I don't know how a Zero would compare against a P39 it could climb at a steeper angle than the Hellcat which gave the Zero an advantage in that type of combat. My suspicion is that the P39 would be in a similar situation.


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## Shortround6 (Mar 21, 2019)

Ivan1GFP said:


> Hello P-39 Expert,
> There was a lot of "Crazy" going on at that time if you think about it.
> In April 1940, the British were willing to contract with North American to build an entirely new fighter that didn't even exist as a paper design. This was early in the Battle of Britain and the outcome wasn't so sure. The fact that things turned out pretty well is a nice story but from the British viewpoint, there wasn't any way they could predict things would go so well.
> 
> ...



Things with the Allison were even stranger than what you list in 1940-41.
While Allison built 1149 engines in 1940 according to one source, a whopping 68 of those engines were completed in the first six months of the year. Allison was engaged in a dispute with the Army over the long nose C-15 engine, Allison wanted to rate it at 1040hp at 14,200ft while the Army wanted 1090hp at 13,200ft. The engine would actual make either goal for a short time. the problem was that Allison wanted the engine rated at 1040hp for take off and to have 1040 as the max power up to the 14.200ft altitude, The Army wanted wanted 1090hp from take-off to 13,200ft. 
Allison began type testing the C-13 engine on Aug 11th 1939. By May 11th they were on the sixth attempt and the fourth engine. The Army Material division agreed to one more attempt at 1090hp military and 960hp normal rating and if unsuccessful they would try Allisons recommendation of 1040hp military and 930 normal. The engine failed in hour 79 at the #8 crank cheek. Finally on Aug 15th 1940 another test was started which the engine successfully completed at 1040hp military and take-off and 930hp normal. 
I am sure Allison was offering 1150hp engines for later delivery but they had no type tested engine of that power available in 1940 although a few developmental engine may have been available. 

In fact, while Allison was offering an 1150hp engine for sale to foreign governments in May of 1940 the engine did not go into production (in P-39 form) until Dec 26th 1940 ( and that is going into production, not first engine delivered) and it passed it's type test Jan 9th 1941. However several parts were still unsatisfactory and the lower crankcase casting and extension drive shaft engine end center bearings had to be modified. 
The first 13 YP-39s were provided with 16 engines using the unmodified crankcases and were operated at reduced power settings until they could be sent back to the factory and modified. The XP-39B crashed on Jan 6th 1940 and was rebuilt, to be crashed again on Aug 6th 1940, Only 28 hours of flight time had been accumulated before it was written off. 
The first of 13 YP-39s was delivered Sept 6th and the last Dec 16th 1940. The first few carried no armament. 
The first P-39C flew in Jan 1941 and it was obvious that these were test/famirazation aircraft as the bulk of the contract had been shifted to combat capable P-39Ds 7-8 months earlier.

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## Ivan1GFP (Mar 21, 2019)

wuzak said:


> Why are the cowl guns heavier on the P-39D than the P-400 or P-39D-2?
> 
> And why is the P-400's pilot heavier?



Hello Wuzak,
I don't really know why the gun weights are different. I am GUESSING it has something to do with whether the gun weight includes the synchronizing mechanism or not. The same equipment must certainly be in place, but may be listed in another category. Note that there is "Miscellaneous Equipment" listed for the aircraft with the lighter cowl guns but not for the regular P-39D.
As for the pilot weight differences, it must be a diet thing.... 
Actually, I believe it is just an unrealistic weight allowance for the early US models of Airacobra. A typical American pilot with Parachute is probably going to weigh a bit more than 160 pounds. My Son is 17 and thin as a stick but at 124 pounds, I don't think he could come in under 160 pounds with flight suit, some basic equipment and a parachute.
This has been a subject of jokes I sometimes tell my friends who may not know better:
Germans must be heavier than Americans because their weight allowance for crew is 100 KG or 220 pounds rather than the typical 200 pounds for US crew. On the other hand, Japanese must be tiny because their weight allowance is only 75 KG.
Maybe the Airacobra was designed to be flown by Japanese?!? The cockpit seems kind of small with a typical US pilot.

Hello P-39 Expert,
I was under the impression that you believed that the P-39D could be brought down to a Normal Loaded weight of 7100 pounds.
That would be the implication if the British had knowingly increased the weight of what became the P-400 to reduce its performance.... But this doesn't seem to be the case if both the US spec P-39D and British spec P-400 are nearly identical in weight.
In comparing climb rates between A6M2 and P-39D, I believe we should be looking at Military Power because that is what would be used in an actual fight. 
If your claim is that there is no real difference there, then there should have been no performance advantage at altitude for the A6M2 at all because neither aircraft would be using Military Power or equivalent until the fight began. 
Such is not the case as shown by the test of A6M2 versus P-39D-1:

_Climb from sea level to five-thousand (5,000) feet indicated. Take-off was accomplished in formation on signal. P-39D-1 was drawing 3000 RPM and seventy (70) inches manifold pressure. Engine started to detonate so manifold pressure was reduced to fifty-two (52) inches. P-39D-1 left the ground first and arrived at five-thousand feet just as Zero was passing four-thousand (4,000) feet indicated. Fifty-two (52) inches manifold pressure could be maintained to four-thousand-five-hundred (4,500) feet indicated. At five-thousand (5,000) feet indicated from a cruising speed of two-hundred-thirty (230) miles per hour indicated the P-39D-1 had a marked acceleration away from Zero. Climb from five-thousand (5,000) feet to ten-thousand (10,000) feet at the respective best climbing speeds, (thus eliminating zoom) P-39D-1 reached ten-thousand (10,000) feet indicated approximately six (6) seconds before Zero. At ten-thousand (10,000) feet indicated, from a cruising speed of two-hundred-twenty (220) miles per hour indicated, P-39D-1 still accelerated away from Zero rapidly. Climbing from ten-thousand (10,000) feet to fifteen-thousand (15,000) feet, both airplanes maintained equal rates of climb to twelve-thousand five-hundred (12,500) feet. Above this altitude the Zero walked away from the P-39D-1. At fifteen-thousand (15,000) feet indicated, from a cruising speed of two-hundred-ten (210) miles per hour indicated the P-39d-1 accelerated away from the Zero slowly.

Climb from fifteen-thousand (15,000) feet indicated to twenty-thousand (20,000) feet indicated the Zero took immediate advantage and walked away from P-39D-1. At twenty-thousand (20,000) feet indicated at a cruising speed of two-hundred (200) miles per hour indicated, and from a starting signal for acceleration, the Zero momentarily accelerated away from P-39D-1. It took P-39D-1 thirty (30) seconds to catch up and go by Zero.

Climb from twenty-thousand (20,000) feet to twenty-five thousand (25,000) feet was not completed as P-39D-1 was running low on gasoline.
_
_Climb from sea level to twenty-five thousand (25,000) feet indicated. Take-off was accomplished in formation on signal, P-39D-1 left the ground with 3000 RPM and 55 inches manifold pressure. P-39D-1 maintained advantage of climb for take-off to fourteen-thousand eight-hundred (14,800) feet indicated. Above this altitude P-39D-1 was left behind reaching twenty-five-thousand (25,000) feet indicated approximately five (5) minutes behind Zero. At twenty-five-thousand (25,000) feet indicated from a cruising speed of one-hundred-eighty (180) miles per hour indicated Zero accelerated away from P-39D-1 for three (3) ship lengths. This lead was maintained by the Zero for one (1) minute and thirty (30) seconds and it took the P-39D-1 thirty (30) more seconds to gain a lead of (1) ship length._


Hello Glider,
The speed issue is the one that comes up the most. Of the aircraft you listed, the only one that was slower that was still being produced at the time would have been the Hurricane. The others were already out of production and the Kittyhawk was a bit faster at least in the way the RAF was using it.
As for the angle of climb,
the P-39D was achieving its best climb at about 160 MPH
Later models of P-39 typically climbed at 170 MPH.
I can't find the best climbing speed of A6M2, but for A6M3-32, it was 146 MPH

- Ivan.

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## Shortround6 (Mar 21, 2019)

wuzak said:


> Why are the cowl guns heavier on the P-39D than the P-400 or P-39D-2?
> 
> And why is the P-400's pilot heavier?




The guns themselves are the same weight, what may be included in the gun weight may have changed. Cocking/charging mechanism. Firing system. Synchronizer? gun heater and so on. 

The P-400's pilot is a real world pilot instead of a fantasy world pilot. Not only does the pilot weight include a 20lb parachute,it includes all the "flying togs" a pilot would wear, including life vest. The only way you are going to get a 160lb dressed/equipped pilot is if you start with 120-130lb naked (or skivvie clad) pilots.


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## Ivan1GFP (Mar 21, 2019)

Hello Shortround6,
Let's see if I understand this correctly....
The 1150 HP Allison engine did not pass its type test until January 1941.
This is the SAME month as the initial delivery of P-39C aircraft with this engine that is not yet in production.
A month later, the P-39D deliveries begin with the same engine which is or isn't in production????

Is this a case of fighters that can't be flown at full power and have ballast in place of guns?

- Ivan.


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## Shortround6 (Mar 21, 2019)

The P-39 1150hp engine did not pass it's type test until Jan 9th, The F type engine used in the P-40D&E didn't start it's model test until Feb 17th 1941.

The 1150hp E series (Airacobra) engine was in production at the very end of 1940. Apparently the US army allowed production to start before a successful type or model test. This was a gamble for both the Army and the manufacturer. remember that Allison had to bring back 228 of the long nose engines and rework them at Allison's expense (16 or 18 still not reworked in the middle of March 1941) because production and deliveries started before a successful type/model test. 

The Army had contracted for 5 F series 1150 hp engines (short nose P-40) back in Jan of 1940 to expedite aircraft testing. One engine went to North American for the NA-73X, one went to Curtiss for the P-40D, two others went to Curtiss for the XP-46 and XP-46A. the fifth engine was supposed to be used for the model test but the engine that completed the model test had a different serial number. The model test was delayed so they could incorporate changes in the crankcases and the connecting rods that other test engines had shown to be needed. 

Allison did an amazing job going from a small shop to a major manufacturer but it was a number of years behind the Merlin and they were still sorting the engine/s out while undertaking massive factory expansion and making hundreds of engines per month.

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## P-39 Expert (Mar 22, 2019)

Ivan1GFP said:


> Hello Wuzak,
> I don't really know why the gun weights are different. I am GUESSING it has something to do with whether the gun weight includes the synchronizing mechanism or not. The same equipment must certainly be in place, but may be listed in another category. Note that there is "Miscellaneous Equipment" listed for the aircraft with the lighter cowl guns but not for the regular P-39D.
> As for the pilot weight differences, it must be a diet thing....
> Actually, I believe it is just an unrealistic weight allowance for the early US models of Airacobra. A typical American pilot with Parachute is probably going to weigh a bit more than 160 pounds. My Son is 17 and thin as a stick but at 124 pounds, I don't think he could come in under 160 pounds with flight suit, some basic equipment and a parachute.
> ...


I do believe the P-39D weight could be reduced to 7162#. 5462# empty, 1700# load (pilot 200, fuel 720, guns/ammo 580, armor plate/glass 130, oil 70).

In comparing climb rates, military power was used until the 5 minute limit was reached. In the "climb from sea level to 25000ft indicated" paragraph the "P-39D-1 maintained advantage in climb for take-off to 14800' indicated." Above this altitude the D-1 was left behind..." 

The 14800' was when the Allison reached the 5 minute limit for military power (3000rpm) and had to reduce power to normal power 2600rpm. That's when the Zero climbed away. The 5 minute limit was increased to 15 minutes mid year 1942. If this engine had the 15 minute limit then the D-1 would have climbed with the Zero all the way up.


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## Shortround6 (Mar 22, 2019)

P-39 Expert said:


> I do believe the P-39D weight could be reduced to 7162#. 5462# empty, 1700# load (pilot 200, fuel 720, guns/ammo 580, armor plate/glass 130, oil 70).



Somehow you have reduced the empty weight of the P-39 by several hundred pounds. The P-39D going 5523lbs, the P-400 -5550lbs the P-39D-2 was 5658, the the P-39K was also 5658 and the P-39L porked up to 5733. These weights for the later aircraft include radios, oxygen and de-icer fluid. The weights for the early aircraft do not include oxygen or radios or flares (night landing?) 




P-39 Expert said:


> The 14800' was when the Allison reached the 5 minute limit for military power (3000rpm) and had to reduce power to normal power 2600rpm. That's when the Zero climbed away. The 5 minute limit was increased to 15 minutes mid year 1942. If this engine had the 15 minute limit then the D-1 would have climbed with the Zero all the way up.



Military power for the Allison engine used in the D-1 aircraft in this test was achieved at 42in. NOT the 52in used in this test which would be WEP or as much as the engine could stand on the day of the test without detonating. The engine could not hold the 52in above 4500ft while climbing but the test makes no mention of the pressures used at the higher (over 5000ft) altitudes, either for the 5000ft increment climbs or the acceleration tests.

the 2nd test was a straight climb to 25,000 starting using 3in more manifold pressure than the previous test (55in) which is 13 in over military power. 

While it was normal to throttle back in normal standardised testing after 5 minutes they sometimes exceeded time limits in combat testing or combat evaluations. This test does not say either way. 
I don't know when the test flying was done but the date on the report is Dec 1942, which means the 15 time limit had been in place for several months. The attempt (failed due to detonation) to use 70in of MAP shows that they were NOT limiting this test to even recommended WEP settings if the engine would tolerate it as the WEP rating for this engine was 56in.

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## P-39 Expert (Mar 22, 2019)

Shortround6 said:


> Somehow you have reduced the empty weight of the P-39 by several hundred pounds. The P-39D going 5523lbs, the P-400 -5550lbs the P-39D-2 was 5658, the the P-39K was also 5658 and the P-39L porked up to 5733. These weights for the later aircraft include radios, oxygen and de-icer fluid. The weights for the early aircraft do not include oxygen or radios or flares (night landing?)
> 
> 
> 
> ...


I'v always seen 5462# as empty weight for the P-39D (not the heavier D-1 which was a virtual copy of the P-400 or the D-2). The P-39F at 5409# was the same as the D except for the hydromatic propeller which weighed 50# less than the Curtiss electric. The L was a little heavier than the K because it reverted temporarily to the heavier Curtiss electric propeller. These were the last models to use the Curtiss Electric propeller, the M, N and Q all used the hydromatic propeller.


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## Shortround6 (Mar 22, 2019)

I don't why or when but different "items" wound up in different categories at different times. Like at some point on P-40s the armor shifted from armament provisions (which is separate from the guns or ammo) to it's own catagory.

It may also depend on where (what publication or document) you are taking your empty weights from. 
From a design standpoint the radio/s are part of the payload. They are not part of the structure or the powerplant and aren't really needed for the airplane to get off the ground, Different Customers will have requirements for different radios. 
However from a pilot's perspective (pilot's manual) the radio is part of the fixed equipment like the instrument panel. The Japanese and Russians may have removed some of theirs but I don't believe the US pilots did. The radios (at least the basic radio in the P-39, the IFF may be different) became part of the basic weight for the pilots. 
The less stuff you have in the list of stuff on the weights and balance charts the simpler they are to use (less mistakes). 

Once you have added certain things in, they are hard to take out. Like structure. A 7,000lb plane stressed for 8/12 Gs service/ultimate has what I would call figures of merit (they may have a real name) of 56,000/84,000. If you increase the gross weight of the plane to 8000lbs you either beef up the structure or accept G limits of 7/10.5 Gs service/ultimate. While they did relax the standard for the Mustang I am not so sure they would do it for the P-39 at an earlier date. Once you have tooled up to build the heavier structure then building light structure planes becomes nearly impossible. The Mustang required quite extensive revision to go to the H model. Curtiss never built a "light" P-40, they built strippers where they pulled out operational equipment and used lightweight accessory parts like Magnesium wheels and aluminium radiators. Now perhaps Bell could have resorted to the same things if the supply had been sufficient or need great enough. 

I will note that according to one account the P-39 had been _designed_ to use a fair amount of magnesium castings instead of aluminum and perhaps aluminum radiators. 
However the state of the art in Magnesium casting and finishing (unprotected magnesium corrodes much quicker than aluminum) and the aluminium radiators not really being ready for volume production in 1938-39 (or even 1941) ended those avenues and that is part of the reason that the prototype was 10% overweight. 
There is sometimes a fine line between designing a state of the art aircraft and one that is made out of unobtainium. 
Bell had also gotten caught by the US enthusiasm for integral fuel tanks. Just seal up parts of the wing and _voila_, fuel storage using already existing structure, no weight wasted on seperate tanks. The Republic P-43, the Vought Kingfisher (not sure about wing tanks on the F4U), Brewster Buffalo and Consolidated PBY all started with integral tanks, there may be others. 
When they had to go to self sealing tanks they had no existing tanks to take-out, help offset the weight of the new tanks.


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## P-39 Expert (Mar 22, 2019)

Shortround6 said:


> I don't why or when but different "items" wound up in different categories at different times. Like at some point on P-40s the armor shifted from armament provisions (which is separate from the guns or ammo) to it's own catagory.
> 
> It may also depend on where (what publication or document) you are taking your empty weights from.
> From a design standpoint the radio/s are part of the payload. They are not part of the structure or the powerplant and aren't really needed for the airplane to get off the ground, Different Customers will have requirements for different radios.
> ...


You are correct, the items included in Empty or Empty Equipped can be different for different planes, even comparing the Weight and Balance Chart from the pilot's manual. Radio equipment was normally included in the Empty category.


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## Ivan1GFP (Mar 22, 2019)

P-39 Expert said:


> I do believe the P-39D weight could be reduced to 7162#. 5462# empty, 1700# load (pilot 200, fuel 720, guns/ammo 580, armor plate/glass 130, oil 70).
> 
> In comparing climb rates, military power was used until the 5 minute limit was reached. In the "climb from sea level to 25000ft indicated" paragraph the "P-39D-1 maintained advantage in climb for take-off to 14800' indicated." Above this altitude the D-1 was left behind..."
> 
> The 14800' was when the Allison reached the 5 minute limit for military power (3000rpm) and had to reduce power to normal power 2600rpm. That's when the Zero climbed away. The 5 minute limit was increased to 15 minutes mid year 1942. If this engine had the 15 minute limit then the D-1 would have climbed with the Zero all the way up.



Hello P-39 Expert,
Your figure for the empty weight for the P-39D is 5462 pounds.
The number I found is 5523 pounds. I believe it is quite possible for BOTH numbers to be correct..... if you take them in context.
Note that for the items that are directly accounted for there are quite a few that are often seen In other weight breakdowns that are missing in the listing I found for the different Airacobra models:
1. Trapped Oil - Note that only Usable Oil is listed here in the disposable loads. There may also be other trapped fluids such as hydraulics for brakes and the like. I know the Airacobra is a mostly electric ship.
2. Engine Coolant
3. Oil supply for the Propeller Reduction Gear up front. Note that unlike most other aircraft, this one has its own oil system for this purpose. Driving this extra pump might also explain minor power differences between E series Allisons and corresponding F series.

In my opinion, IF this was the difference between your empty weight and mine, it appears to be rather small.
The most detailed manual seems to be the Russian version, so it might be worthwhile to go looking there for details.
You list the weight of P-39F as being 53 pounds less. Does this include any additional equipment and oil volume required to run a hydromatic type propeller?

You state that the P-39D-1 was heavier than a P-39D. My understanding of the differences is that the D-1 added a fin fillet that was retrofitted to most D airframes and the 37 mm cannon was replaced with a 20 mm Hispano. Other than that, they should be identical. There should have been more detail differences especially in armour between P-39D-1 and P-400.
The P-39D-2 obviously would weigh more because it had a different engine (V-1710-63 as compared to V-1710-35).

The test description I posted is obviously against the A6M2 captured in the Aleutians.
As Shortround6 already pointed out, the folks flying the P-39D-1 were pushing as hard as they could.
70 inches Hg was never authorized for ANY of these aircraft AND they were using it for Take-Off!
Even then, the test report notes that they could not sustain even War Emergency Power (52 inches Hg) above 4500 feet and considering what the climb rate would have been, it was most likely the supercharger running out of capacity and not a time limitation. This was pretty typical for the -35, -39, -63, and -73 engines.
Note that the A6M2 in this test also had an "Overboost" power setting but it was never used in any of the tests.
Another interesting detail is that the automatic mixture control on this aircraft was not working.
The starting speeds chosen for acceleration tests also suggest that the intent was to be fairly close to the maximum level speed of the A6M2 to make the American fighters look better.

- Ivan.

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## P-39 Expert (Mar 25, 2019)

Ivan1GFP said:


> Hello P-39 Expert,
> Your figure for the empty weight for the P-39D is 5462 pounds.
> The number I found is 5523 pounds. I believe it is quite possible for BOTH numbers to be correct..... if you take them in context.
> Note that for the items that are directly accounted for there are quite a few that are often seen In other weight breakdowns that are missing in the listing I found for the different Airacobra models:
> ...


Thanks Ivan.

The D-1 was about 200# heavier than the D.

The F was about 50# lighter than the D because the only difference in the two planes was the new Hydromatic propeller on the F which was about 50# lighter than the Curtiss Electric propeller on the D.

Regarding the test with the Zero, in my opinion the reduction in climb rate was because of the required reduction from 3000rpm (takeoff and Military) to 2600rpm (normal or max continuous) at 5 minutes. By mid '42 this 5 minute restriction was increased to 15 minutes. This test used the heaviest early P-39 model (7850#), obviously the 5 minute restriction was still being observed, War Emergency Power was just being implemented on Allison engines at the time of this test, and it's not known if this D-1 still had backfire screens.


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## Shortround6 (Mar 25, 2019)

That is a strange concluslion to reach from reading the test report. 



Ivan1GFP said:


> Climb from sea level to five-thousand (5,000) feet indicated. Take-off was accomplished in formation on signal. P-39D-1 was drawing 3000 RPM and seventy (70) inches manifold pressure. Engine started to detonate so manifold pressure was reduced to fifty-two (52) inches. P-39D-1 left the ground first and arrived at five-thousand feet just as Zero was passing four-thousand (4,000) feet indicated. Fifty-two (52) inches manifold pressure could be maintained to four-thousand-five-hundred (4,500) feet indicated. At five-thousand (5,000) feet indicated from a cruising speed of two-hundred-thirty (230) miles per hour indicated the P-39D-1 had a marked acceleration away from Zero. Climb from five-thousand (5,000) feet to ten-thousand (10,000) feet at the respective best climbing speeds, (thus eliminating zoom) P-39D-1 reached ten-thousand (10,000) feet indicated approximately six (6) seconds before Zero.



Now please note that they are using a manifold pressure well into WEP range (and in fact tried to exceed the WEP rating) on take-off. 
The climb was interrupted at 5,000, which should have been reached in 2 minutes or less. The "book" rating for this engine was 56in at 4300ft. Perhaps this engine wasn't running quite right? they were testing at more than 59 degrees F? some other problem? 
The planes then leveled off and assumed the pre-arranged "cruise" speed for the acceleration test, Engine would *not* be running at either WEP or Military power at this point (thus resetting the clock for the 5 minute rule?) Going to full throttle on signal to do the acceleration test, *then* throttling back to best climb speed *before *doing the 5,000 to 10,000ft climb (again should be done in under two minutes) so even at whatever pressure the engine would give them they have not run out the 5 minute clock before setting up for the acceleration test. Once again there is a brief period (or two) of less than full throttle as planes set up for the acceleration test and then as they slow down to best climb speed after the acceleration test. Process is repeated for the 10,000 to 15,000ft climbs and the 15,000ft to 20,000ft climbs. 

In other tests it only takes a P-39D 2.8 minutes to go from 15,000ft to 20,000ft even at 2600rpm. So if they started at 15,000ft and were allowed to use full throttle ( because the engine had started full throttle after a cooling off period) you aren't going to come close to the 5 minute limit being a problem. 

The ONLY part of this test were the 5 minute limit _might _have come into play was on the 2nd flight (after they refueled). where the P-39D took off using 55in of MPA ( *one* inch less that full WEP). The test does not say one way or the other. The test does not give the date/s of the flights, just the date of the report which is AFTER WEP being approved and AFTER the Military power rating being extended to 15 minutes. Military power on this engine was 42in. 

Please note that a P-39K was rated (in the manual) as making it to 15,000ft in 5.9 minutes at 7400lbs and 6.3 minutes at 7800lbs and that is using 3000rpm all the way and on a 32 degree F day. Chart says to add 10% to the time to altitude for every 20 degrees F above freezing so even a 72 degree day could be 1 minute 15 seconds slower.

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## Ivan1GFP (Mar 25, 2019)

P-39 Expert said:


> Thanks Ivan.
> 
> The D-1 was about 200# heavier than the D.
> 
> ...



Hello P-39 Expert,
Where was the extra 200 pounds added from the P-39D to P-39D-1?
Note that with substitution of a 20 mm HS 404 cannon in place of the 37 mm cannon, there was a loss of 111 pounds for the gun and about 28 pounds for ammunition so for the D-1 to be 200 pounds heavier, it needs to have about 340 pounds of additional equipment. The engine, other armament and armour should be the same between the two or do you know that not to be the case?

Regarding the test against Koga's Zero, note that the Airacobra crew made no pretense of following the limitations of the operating manual as can be seen by attempting to run at 70 inches Hg. They also were not running at Military power but instead were running at War Emergency until the supercharger was unable to maintain boost at 4500 feet.
There is no indication that the Airacobra was run at Max Continuous for these tests.

Note that historically, the Airacobra always seemed to have trouble doing intercepts above about 15,000 feet and its performance here seems to fit in pretty well with known history.

My belief is that the fact that the aircraft could even be flown at 70 inches Hg is a pretty good indication that neither snow screens nor backfire screens were installed. Note that the famous Allison memo points out that they did not believe it was possible to achieve 70 inches Hg without a significant ram AND over-revving the engine.

I do not believe there is any mention of a gross weight of the P-39D-1 used in the test and the fact that it was running low on fuel at one point during the test may be an indication that it was not carrying a full fuel load. (?) Fairly or unfairly, these folks were trying to make the Airacobra look good relative to the captured A6M2.

- Ivan.

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## Shortround6 (Mar 25, 2019)

Ivan1GFP said:


> I do not believe there is any mention of a gross weight of the P-39D-1 used in the test and the fact that it was running low on fuel at one point during the test may be an indication that it was not carrying a full fuel load. (?) Fairly or unfairly, these folks were trying to make the Airacobra look good relative to the captured A6M2.




That or trying to figure out how to beat the A6M2

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## P-39 Expert (Mar 26, 2019)

Ivan1GFP said:


> Hello P-39 Expert,
> Where was the extra 200 pounds added from the P-39D to P-39D-1?
> Note that with substitution of a 20 mm HS 404 cannon in place of the 37 mm cannon, there was a loss of 111 pounds for the gun and about 28 pounds for ammunition so for the D-1 to be 200 pounds heavier, it needs to have about 340 pounds of additional equipment. The engine, other armament and armour should be the same between the two or do you know that not to be the case?
> 
> ...


If they were trying to make the Airacobra look good, why didn't they use a P-39N? It was just becoming available about the time of these tests, was faster at all altitudes (all P-39s were) and climbed much better at all altitudes.


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## Peter Gunn (Mar 26, 2019)

Wait, from what I've read here, the P-39 could out climb the Allison powered Mustangs, was only ~10MPH slower and had almost the same range and if outfitted properly, could intercept bombers at 31,000 feet.

Yet somehow North American hoodwinked the Brits into buying as many Allison Mustangs as they could build (and would have kept buying them as long as NAA was building them) meanwhile, these same Brits conspired to add weight and put the kibosh on this wonderful little Bell fighter because... reasons.

Either the Brits have some serious 'splainin to do or Bell was just totally incompetent at politicking and greasing the correct palms while NAA was apparently a past master at same...

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## Kevin J (Mar 26, 2019)

Peter Gunn said:


> Wait, from what I've read here, the P-39 could out climb the Allison powered Mustangs, was only ~10MPH slower and had almost the same range and if outfitted properly, could intercept bombers at 31,000 feet.
> 
> Yet somehow North American hoodwinked the Brits into buying as many Allison Mustangs as they could build (and would have kept buying them as long as NAA was building them) meanwhile, these same Brits conspired to add weight and put the kibosh on this wonderful little Bell fighter because... reasons.
> 
> Either the Brits have some serious 'splainin to do or Bell was just totally incompetent at politicking and greasing the correct palms while NAA was apparently a past master at same...



This is simply not true. The Bell fighter had a list of issues to sort out and it simply lacked the range of the Allison Mustang. The Soviets took them, sorted out the problems and unlike the Americans operated it successfully until the end of the war. They didn't need it as a fighter with high altitude capability or range. Over half the Soviet top scoring aces flew it. As for the Americans, it simply lacked the range to be useful.


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## Ivan1GFP (Mar 26, 2019)

P-39 Expert said:


> If they were trying to make the Airacobra look good, why didn't they use a P-39N? It was just becoming available about the time of these tests, was faster at all altitudes (all P-39s were) and climbed much better at all altitudes.



Hello P-39 Expert,
My belief is that this report was intended to show how US fighters compared favorably to A6M2. To show how a P-39N performed better was not useful because that is not what was in service at the front lines at the time. This report is trying to convince folks flying the older P-39D that they have a competitive fighter.
If one does not notice the details of the test, the summary might be: The acceleration and speed of the Airacobra is better at all altitudes and decreasing slightly past 20,000 feet. The climb rate of Airacobra is superior at all altitudes below 15,000 to 20,000 feet and greatly superior near sea level.
If one looks at the details, one can see that the Airacobra is using War Emergency Power or even higher to achieve its low altitude performance while the A6M2 never uses more than "Military Power" with an engine that does not have functioning automatic mixture control and has some fit and finish problems and is (IMO) about 10 MPH slower than an operational example would be. On overboost, there should be an even greater speed difference.
If the intent had been to compare actual acceleration, they might have started the test runs at a much lower speed such as 150-175 MPH TAS and see how quickly the A6M2 pulls away.

Hello Shortround6,
These folks were trying hard to beat the A6M2 in these tests regardless of whether the tactics would work or not in the field.
The interesting thing is that although the P-39 is supposed to be substantially faster, it didn't seem to be so hard to catch according to combat reports. Perhaps it had something to do with much of its speed coming from the ram effect you mentioned earlier.

- Ivan.

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## special ed (Mar 26, 2019)

If I may chime in, Saburo Sakai in his book describes just such a combat and reports how well flown the American and his P-39 were. The P-39 jock may have survived against a lesser experienced Japanese pilot.


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## Shortround6 (Mar 26, 2019)

Kevin J said:


> This is simply not true.


I beleive it was sarcasm, doesn't need to be true literally. 



Kevin J said:


> The Bell fighter had a list of issues to sort out and it simply lacked the range of the Allison Mustang.


It lacked a few other things besides range, like speed. In some tests the Allison Mustang was 20mph faster than P-39 with an equivalent engine. 
which means things like at 13,000ft and doing about 370mph the Mustang can still climb (slowly), the P-39 can't unless it slows down a bit. 



Kevin J said:


> The Soviets took them, sorted out the problems and unlike the Americans operated it successfully until the end of the war. They didn't need it as a fighter with high altitude capability or range.



Depends on what you mean by operated successfully. The Americans certainly "operated" P-39s during 1942/43/44 and in combat zones. They just didn't push them to very front as they had better planes available, in addition to different tactical needs. The Americans did not suffer any large number of operational losses(non combat) or planes losing their way (faulty compass) so a lot of the early operational problems were solved by the Americans also. Of the 9500 Airacobras built the Russians got about 1/2, yes the Americans used a fair number as advanced trainers but P-39s were not phased out of combat until Aug/Sept of 1944 in US combat units. They were being used mostly for ground support.

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## Ivan1GFP (Mar 26, 2019)

special ed said:


> If I may chime in, Saburo Sakai in his book describes just such a combat and reports how well flown the American and his P-39 were. The P-39 jock may have survived against a lesser experienced Japanese pilot.



Hello Special Ed,
If the combat you are referring to is the same one I am thinking of, then the problem was that the P-39 simply ran out of room at ground level and had to pull up. According to the test we have been discussing, the P-39 should have had a huge advantage in speed and climb at sea level. Its speed advantage from sea level to 5,000 feet according to these tests was around 35 MPH and yet the practical difference seems to have been much less than that.

- Ivan

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## special ed (Mar 26, 2019)

However, all of these tests are akin to "lab tests" rather than real world with worn engines, frequently overboosted ( savings one's life doesn't limit the boost to 5 min. or 15 min.) and repaired in the field.

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## Shortround6 (Mar 26, 2019)

You also have a big variable in that the "tests" are started with both planes at the same speed or close to it. 
In combat one plane or the other may have 10-30mph advantage over the 'test' plane. 

Lets face it a 10% advantage in speed can mean a difference but is unlikely to be noted in a combat report (assuming one is made) 

You also need a a certain amount of altitude for certain tactics to work, diving away when you are only 3-4000 ft above the ground/sea is unlikely to get you enough distance to get out of the fight.


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## special ed (Mar 26, 2019)

I just went to look for my Allison book, which once again is mislaid, to verify an example discovered when reading Dwane Schultz's book on the AVG. In the real world, the long nose Allisons seemed to have gearbox failure more often than expected. Reading the story of the Allison, In order to fill the emergency requirement for the AVG, Supervisors were called to work weekends and overtime to hand assemble engines from the reject pile of parts and assemblies, if I remember right. My assumption is that these engines put together by the most experienced, and knowing where they were going, probably put out another 50hp which contributed to gear failure at full throttle in combat.

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## Peter Gunn (Mar 26, 2019)

Kevin J said:


> This is simply not true. The Bell fighter had a list of issues to sort out and it simply lacked the range of the Allison Mustang. The Soviets took them, sorted out the problems and unlike the Americans operated it successfully until the end of the war. They didn't need it as a fighter with high altitude capability or range. Over half the Soviet top scoring aces flew it. As for the Americans, it simply lacked the range to be useful.



Shortround was correct, just a little snarky humor injected into a looooong discussion on the Iron Dog.

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## P-39 Expert (Mar 26, 2019)

Peter Gunn said:


> Wait, from what I've read here, the P-39 could out climb the Allison powered Mustangs, was only ~10MPH slower and had almost the same range and if outfitted properly, could intercept bombers at 31,000 feet.
> 
> Yet somehow North American hoodwinked the Brits into buying as many Allison Mustangs as they could build (and would have kept buying them as long as NAA was building them) meanwhile, these same Brits conspired to add weight and put the kibosh on this wonderful little Bell fighter because... reasons.
> 
> Either the Brits have some serious 'splainin to do or Bell was just totally incompetent at politicking and greasing the correct palms while NAA was apparently a past master at same...


If they have the same engine (either the 8.8 gears or the 9.6 gears) the P-39 would outclimb the P-51 since it was 800# lighter and was only 10-15mph slower since the P-51 was cleaner aerodynamically. 

P-39 never had near the same range since the P-51 carried 50% more internal fuel. The modification to substitute fuel tanks for the .30 caliber wing guns would have greatly increased the P-39's internal fuel, but that modification was never implemented. Except on the post war racing planes. 

The reasons for the Brits love of the Mustang and hate of the Airacobra have been beaten to death on this board. Their reasons for disliking the P-39 were largely financial. The Russians loved the P-39 and didn't care for the P-51. Their reasons were largely survival. 

Was the Allison P-51 better than the P-39? In speed and range, yes. In climb and ceiling, no.


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## Shortround6 (Mar 26, 2019)

P-39 Expert said:


> If they have the same engine (either the 8.8 gears or the 9.6 gears) the P-39 would outclimb the P-51 since it was 800# lighter and was only 10-15mph slower since the P-51 was cleaner aerodynamically.
> 
> P-39 never had near the same range since the P-51 carried 50% more internal fuel. The modification to substitute fuel tanks for the .30 caliber wing guns would have greatly increased the P-39's internal fuel, but that modification was never implemented. Except on the post war racing planes.
> 
> ...



The Mustang was often more than 10-15 faster. 
Climb is the power to weight ratio at best climb speed. If lower drag plane is using less power simply to fly at climb speed then it has more power to climb. I am not saying the Allison Mustang out climbed the P-39, just that the difference might not be as great as a comparison of the weight would suggest.

You also keep wanting it both ways, the speed and climb of a light weight P-39 but the range/endurance of one carrying 420-500lbs of extra fuel and tanks. 

You have also never shown any proof what so ever that the British disliked the P-39 on finicial grounds. Show us the proof or shut up about it.
The British certainly showed no tendency to try to get out of other contracts including Vultee Vengence or Brewster Burmuda contracts.

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## special ed (Mar 26, 2019)

Agree about Vengeance and Burmuda.


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## Glider (Mar 26, 2019)

P-39 Expert said:


> The reasons for the Brits love of the Mustang and hate of the Airacobra have been beaten to death on this board. Their reasons for disliking the P-39 were largely financial. .



Actually no, the comment that has been beaten to death on this board is your repeated statement that the British were trying to get out of their commitments for financial reasons. An often repeated comment, that has never, and almost certainly will never, be substantiated. If you had firm evidence, (make that any evidence) I am very confident that you would have supplied it

The P39 as supplied to the RAF wasn't combat worthy, wasn't up to scratch, missed all its performance targets by a substantial margin and the RAF had better aircraft namely the Spit V, coming on stream

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## P-39 Expert (Mar 26, 2019)

Shortround6 said:


> The Mustang was often more than 10-15 faster. *And often less.*
> Climb is the power to weight ratio at best climb speed. If lower drag plane is using less power simply to fly at climb speed then it has more power to climb. I am not saying the Allison Mustang out climbed the P-39, just that the difference might not be as great as a comparison of the weight would suggest.
> 
> You also keep wanting it both ways, the speed and climb of a light weight P-39 but the range/endurance of one carrying 420-500lbs of extra fuel and tanks. *I have it both ways. The extra fuel would have added negligible extra weight since it was in place of the .30 cal MGs.*
> ...


 *See above.*


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## DerAdlerIstGelandet (Mar 26, 2019)

Everyone remain calm, breath and relax, or we shall put this thread to bed for a while.

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## pbehn (Mar 26, 2019)

I have a back ache from putting these fuel tanks in and taking them out again.

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## wuzak (Mar 26, 2019)

P-39 Expert said:


> The reasons for the Brits love of the Mustang and hate of the Airacobra have been beaten to death on this board. Their reasons for disliking the P-39 were largely financial. The Russians loved the P-39 and didn't care for the P-51. Their reasons were largely survival.



As the British government was able to print its own money, purchasing items in an emergency situation was no issue.

Lend-Lease simply pushed the debt further down the road. The British government still owed the money for the items supplied.

As the issue was survival, any aircraft that the British could lay their hands on that could help with that goal would be gleefully accepted. The P-39 was clearly not up to scratch.




P-39 Expert said:


> Was the Allison P-51 better than the P-39? In speed and range, yes. In climb and ceiling, no.



For the earlier engines with the 8.8 gears the P-51 was faster to 10,000ft, line ball to 25,000ft and had a ceiling about 250ft higher.
http://www.wwiiaircraftperformance.org/P-39/P-39D_41-6722_PHQ-M-19-1325-A.pdf 
http://www.wwiiaircraftperformance.org/mustang/P-51_41-37320_PHQ-M-19-1415-A.pdf 

The top speed was nearly 30mph faster at a thousand feet lower than for the P-39 - 396mph @ 12,650ft vs 368mph @ 13,800ft.

The P-51 appears to have been fitted with 4 cannon.

With the higher rated altitude V-1710, the P-51A was a bit slower than the P-39N to 15,000ft, by about 36s. And by 2 minutes to 25,000ft.
The P-51A was about 18mph faster at ~10,000ft, around where both had their maximum speed.

The ceiling was about 3,000ft lower for the P-51A.

http://www.wwiiaircraftperformance.org/mustang/P-51-A_43-6007_Flight_Tests.pdf
http://www.wwiiaircraftperformance.org/P-39/P-39N_FS-M-19-1487-A.pdf

Compared to the P-39M, the P-51A was faster to 15,000ft, just, and they were line ball to 25,000ft. Ceiling was 800ft higher for the P-39M. The P-39M was about 30mph slower than the P-51A at a similar altitude for top speed.

http://www.wwiiaircraftperformance.org/P-39/P-39M-3_42-4706_FS-M-19-1511-A.pdf




P-39 Expert said:


> The Mustang was often more than 10-15 faster. *And often less.*



And often a lot more. You would have to plot the curves against each other to find where the maximum and minimum differences were.




P-39 Expert said:


> You also keep wanting it both ways, the speed and climb of a light weight P-39 but the range/endurance of one carrying 420-500lbs of extra fuel and tanks. *I have it both ways. The extra fuel would have added negligible extra weight since it was in place of the .30 cal MGs.*



That depends how much fuel you would be storing. And you may be forgetting the weight of the tanks themselves.

Surely the .30mgs don't weigh 420-500lbs?




P-39 Expert said:


> The British certainly showed no tendency to try to get out of other contracts including Vultee Vengence or Brewster Burmuda contracts.*What about the
> lightning?*



As supplied, the P-38 was a turd.

The Lightning I didn't have turbos and had both engines turning the same direction. 

The bulk of the British order was to be the Lightning II, which had handed engines and turbochargers. But only one was built. Not sure why - maybe the USAF pulled rank on that one?

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## ThomasP (Mar 26, 2019)

Hey Wuzak,

I don't know if this answers your question, but the primary reason the UK cancelled the Lightning II and P-38F orders is that the Spitfire Mk IX came along. With the advent of the Mk IX in early- to mid-1942 the need for a high altitude interceptor could be met by a single engine fighter built in the UK. Since the Lightning Mk II with turbos and the 
P-38F would not be available until mid- to late-1942 there was no longer a point to the purchase.

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## Shortround6 (Mar 26, 2019)

The P-38 may be the ONLY aircraft the British got out of a cash deal for. 
Without _knowing_ the exact financial details, instead of guesses or accusations of nefarious activity most of us are just speculating. 

At least Lockheed may have warned the British (and the French who originated the both engines turning in the same direction thing) that performance would not be up to the "normal" version/s.

Most accounts of these aircraft skip over the financial details and such terms as requisitioned as in "......nearly 200 of the British direct-purchase Airacobras still in the USA were promptly requisitioned by the USAAC. " doesn't tell us if the British got their money back directly or were given credits to offset some lend lease orders or if any compensation was paid or credited in any way. Some more sensational accounts claim the British "dumped" the unwanted Airacobras on the US. 

As far as the P-38 story goes, that too has some confusing details or dates. One account says the the French (and British ) skipped the turbo because of doubts that the US would allow it to be exported and they wanted the planes as soon as possible, perhaps starting delivery in one year, Lockheed missed this by a good 9 months. Planes ordered before France fell were not delivered to England until March of 1942. Accounts differ as when the contract was amended so that only the first 143 would be built without turbos and the last 524 would be delivered with turbos as Lightning IIs. Some accounts say the change was in July of 1940 and other accounts say July of 1941. In any case the 140 unwanted P-38s were also taken over by the US army and used as trainers. of the other 524 aircraft. "Twenty-eight other British-ordered aircraft were completed as P-38F-13-LO for the USAAF, 121 as P-38F-15-LO, 174 as P-38G-13-LO, and 200 as P-38G-15-LO. "

Now considering that Lockheed had only built 207 P-38s in 1941 and 1479 in 1942 the picking up of 664 British airframes provided a considerable boost to the USAAF. 
BTW one Lightning II was completed as a P-38F-13-LO and became much photographed. 





AF221 is a British serial number. 

Now most accounts say the British refused delivery of the model 322s, not one account that I have seen says the British got their money back or who (the US Army?)paid Lockheed what. Now perhaps Lockheed, with orders for hundreds of Hudsons and hundreds of Ventura's and ready customer for 322s as they were, didn't kick up a fuss, I don't know. 

The US forces certainly "obtained" hundreds if not well over 1000 aircraft that were ordered by the British, either cash or lend-lease. 
Again, without specific contracts and/or amendments we are only speculating as to what the financial arrangements were and/or the motives.

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## XBe02Drvr (Mar 27, 2019)

Peter Gunn said:


> somehow North American hoodwinked the Brits into buying as many Allison Mustangs as they could build (and would have kept buying them as long as NAA was building them) meanwhile, these same Brits conspired to add weight and put the kibosh on this wonderful little Bell fighter because... reasons.


Peter, you'd look rather funny with a tongue-sized hole in your cheek! You're stretching it near the failure point. And Xpurt's nose is starting to resemble Pinocchio's. Trying to make a plane a full aeronautical generation (if only three short years) more advanced, look inferior to a Larry Bell imaginary figment by making best-case, worst-case comparisons, stretches even my gullible credulity to the breaking point. If planes in actual combat historically can't duplicate these optimistic performance numbers, then they're little better than flim-flam and fodder for armchair aviators and historical revisionists.
The Allison Mustang had:
1) MORE RANGE
2) Better aerodynamics (less cooling drag and better L/D with its near laminar flow wing.
3) More room for growth (it could take on armament/armor/fuel protection weight with less loss of performance.
4) It was upgradable in the propulsion department without serious penalties in handling or structure.
All in all, a WAY better investment.
My dad (4F, not draft fodder) worked at Bell Niagara as a DCAS agent the last two years of the war, and had very little good to say for the place.
"Bunch of money-grubbing crooks!" His job wiih DCAS(Defense Contract Assurance Service) was to catch Bell employees artificially jacking up the costs of production to make more profit on their cost-plus contract. He said the rank and file workers were ed with management's shenanigans and were quick to tip off DCAS when schemes were afoot. The schemes got rather creative at times.
This is getting old. Color me gone.
Cheers,
Wes

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## Peter Gunn (Mar 27, 2019)

XBe02Drvr said:


> Peter, you'd look rather funny with a tongue-sized hole in your cheek! You're stretching it near the failure point.
> 
> *SNIP*
> 
> ...



Wes,

I must admit, my cheek was hurting pretty bad after that post, in fact, I think I have a temporary speech impediment from it now... 

Pete

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## pbehn (Mar 27, 2019)

The conversation is a slipping ratchet, it appears to be making progress then it hits the "The British didn't want to pay tooth" and slips back to the start again.

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## special ed (Mar 27, 2019)

This is very much like an occasion years ago (the late 60s) at my office. A big sales meeting was called in Atlanta and the sales manager and the top salesman were to go. When they were to make ticket reservations, the salesman said he would go by train because he didn't fly and has never flown. When asked about his Army time he said he always traveled by train. The manager pointed out how it would look if he went by plane and his top salesman went by train. So the manager began to show him newspaper stories of how safe air travel was, how many air miles flown without incident and every time an agreement was made, the manager would come out of his office and say "Look, another one went down in Spain" or wherever. Then. the build up of confidence would begin again. The salesman finally agreed he would fly, but he needed booze before boarding. A bet was made if the salesman could fly sober, the manager would pay his bar tab the entire week in Atlanta. We found out they went to the counter and the manager told the agent "Give us two chances to Atlanta" and the salesman did a 180 straight to the bar. That's why the manager was the manager.

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## gjs238 (Mar 28, 2019)

How early could the Army have reasonably pulled the plug on the P-39 and called it quits, or at least keep it in a developmental stage?
And what might have the ramifications been?
Perhaps have Bell build something else under license?
Build more P-40's to fill the void? Perhaps NAA would have stepped up and said, hey, we can build a better P-40?

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## fubar57 (Mar 28, 2019)

Flawed Fighter: Bell P-39 Airacobra


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## Shortround6 (Mar 28, 2019)

gjs238 said:


> How early could the Army have reasonably pulled the plug on the P-39 and called it quits, or at least keep it in a developmental stage?
> And what might have the ramifications been?



Unless they call it quits in 1939 they are stuck. It seems take around a year to go from an order for an existing, flying prototype to _starting _production (5th to 10th aircraft not 1 or two 2 and then as several month gap.) In Dec of 1940 AHT claims that Bell had 1600 P-39s (of whatever kinds) on order (or at least letters of intent?) but they had only delivered 13 aircraft in 1940 and 10 of them were in Dec, You already have hundreds of sets of parts for things like landing gear, brakes, radiators and whatever forgings/casting are done by outside contractors and not in house. This parts may not be complete but are in process. Switching to a different aircraft means re-ordering all these parts from perhaps hundreds of outside suppliers. 

Bell did manage to build 926 P-39s in 1941 and 1932 in 1942 so adjust production as you see fit even if they made somebody else's plane. Hundreds of planes not built during this time? 

Bell built 4947 P-39s in 1943 so again, how long do you shut down the factory to switch over to something else?


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## fubar57 (Mar 28, 2019)

They were working on another doozy in '42 Bell XP-77 - Wikipedia


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## Shortround6 (Mar 28, 2019)

fubar57 said:


> They were working on another doozy in '42 Bell XP-77 - Wikipedia


 Which strangely came in overweight and underpowered........... go figure 

Bell was not entirely to blame, see, 
XP-48





Not funded after review and




I don't know designed it but the company was headed by Preston Tucker of Tucker car fame.
Power was to come from an eight cylinder Miller engine (he had sold his 4 cylinder engine to Offenhauser) company went bankrupt before construction really began.


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## drgondog (Mar 29, 2019)

By 1942, the closest fit to any mission role for AAF for the P-39D was tactical recon/ground support. Low ceiling, heavy (unreliable 37mm M-4) armament, dubious low speed handling, short range - but it was fast and in serial production. It slotted better in SWP (fewer options for AAF, so go with what you have) than ETO and not deemed comparable to either the Spit In interceptor, or Hurricane (or Mustang or Typhoon) in Ground Support/recon. It would marginally out turn and outclimb the Mustang so it was preferable to VVS in their battlefield air supremacy role - and it was in serial production. When the P-40E emerged it was deemed more suitable as an all around fighter, When the P-47C emerged it was deemed more suitable as an all around fighter - with a ceiling and speed comparable to the P-38F. In 1942 when the A-36 and P-51-NA/Mustang IA emerged both were deemed more suitable to Ground Support and TacR role, better all around fighters. With wing racks on the A-36 and P-51A -combined with maueverability/speed and range - they were better than the P-40 and both P-40 and P-39 orders wound down very rapidly in 1943 - also impacting Allison. Had the VVS not sent some top engineers to Bell for P-63 improvements, it would have been a failure in context of 'better than P-39Q. The AAF did Bell huge favors by shuttling P-39/P-63 off to Lend Lease for Russia. As a track record for both design and R&D, Bell and Curtiss both were major disappointments to AAC and that is the reason they were forever out of the fighter business by the end of 1944 - as a consideration for future requirements.

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## P-39 Expert (Mar 29, 2019)

gjs238 said:


> How early could the Army have reasonably pulled the plug on the P-39 and called it quits, or at least keep it in a developmental stage?
> And what might have the ramifications been?
> Perhaps have Bell build something else under license?
> Build more P-40's to fill the void? Perhaps NAA would have stepped up and said, hey, we can build a better P-40?


Excellent idea with 20/20 hindsight.

While we're at it, let's pull the plug on all of them except the P-51.

Who ordered these planes anyway? The P-40 was slower, climbed slower and had a lower ceiling (and a narrow landing gear). The P-38 couldn't dive and the P-47 couldn't climb. Neither could outturn ANY of their adversaries, either German or Japanese. P-47 had the endurance of a Spitfire and the P-38 would freeze you to death at altitude not to mention the power limitations of the intercoolers. Wonderful planes.

And the costs were excessive. Take a P-38 and a P-47, average their unit costs ($120k and 80k) and you can buy TWO Mustangs at $50000 each for every one P-38/47.

Cancel ALL of them. 14000 P-40s, 13000 P-39/63s, 9500 P-38s and 15600 P-47s. We could have had 77000 P-51s (in addition to the 15000 that were actually produced) for what was paid for the 52000 other fighters.

Just think of it, a logistic dream standardizing on one fighter with one type armament. The P-51 could have worked it's way up from the Allison to the single stage Merlin and on to the two stage Merlin and even the two stage Allison if needed or convenient. Fast with plenty of range for both the ETO and the PTO. 

What in the world was Hap Arnold thinking?

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## fubar57 (Mar 29, 2019)



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## Shortround6 (Mar 29, 2019)

P-39 Expert said:


> Who ordered these planes anyway? The P-40 was slower, climbed slower and had a lower ceiling (and a narrow landing gear). The P-38 couldn't dive and the P-47 couldn't climb. Neither could outturn ANY of their adversaries, either German or Japanese. P-47 had the endurance of a Spitfire and the P-38 would freeze you to death at altitude not to mention the power limitations of the intercoolers. Wonderful planes.




A little less hyperbole if you please. 

I know (or really hope) you are being sarcastic but let's face it. The P-39 didn't meet the advertising hype that Bell had built up around it (more than a few other planes didn't either).
It was one of two fighters the US could have in production in large numbers in 1941/42. 
Let's also remember (sorry P-40 fans) the Army didn't really want P-40s either. They ordered them in large numbers because they could get them quick. It was P-40s and P-39s or nothing basically on 1941-42. And a good part of 1943.

SO the question is *when*, once you decide to build the P-39 to begin with, can you afford to stop production and change to something else which could take 4-8 months. P-39 production averaged 412.5 aircraft a month in 1943. Even if 1/2 are going to Russians at what point in 1943 is the war going so well that you can afford to not produce about 1200 fighters for the USAAF and Allied (non Russian) air forces?

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## Shortround6 (Mar 29, 2019)

The US (and the world) got P-40s, not because they were really great (I am not saying they were bad) but because they were available. 

The US built 1685 fighters in 1940. 
481 of them were Hawk 75s/Mohawks.
778 of them were Hawk 81s/Tomahawks/P-40s
160 of them were Buffaloes
103 of them were Grumman F4fs
102 of them were P-35s or Swedish EP-1s. 

The remaining 61 planes were split between 7 different types, including 13 YP-39s (most, if not all without guns).

In 1941 Curtiss built 2248 P-40s, Republic built 1 P-47, Lockheed built 207 P-38s (remember those hundreds of P-38s ordered by the French and British in the spring of 1940?) 
Bell built 926 P-39s. NA built 138 Mustangs and Grumman built 324 F4Fs. 

Curtiss, followed by Bell, had the only viable mass production fighter facilities in the US at the time. Compounded by the the R-2800 only going into production at the very end of 1940. 

The P-47 didn't reach it's 1000th plane produced until the spring of 1943 over two years after the 1000th P-40 and about 1 1/4 years after the 1000th P-39. 

The P-47 and P-38 may have been what the Army wanted, the P-39 and P-40 were what they could get.

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## GrauGeist (Mar 29, 2019)

Republic also manufactured 272 P-43 Lancers between 1940 and 1941.

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## pbehn (Mar 29, 2019)

P-39 Expert said:


> Just think of it, a logistic dream standardizing on one fighter with one type armament. The P-51 could have worked it's way up from the Allison to the single stage Merlin and on to the two stage Merlin and even the two stage Allison if needed or convenient. Fast with plenty of range for both the ETO and the PTO.
> 
> What in the world was Hap Arnold thinking?


Except that the Spitfire Mk IX and the Mustang Mk I appeared in service in UK at almost the same time, mid 1942 (Mustang MkI in May Spitfire Mk IX in July). Mr Arnold was doing what any rational person would do, using what he had in the best way possible until he had better stuff to use.

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## gjs238 (Mar 29, 2019)

Shortround6 said:


> Unless they call it quits in 1939 they are stuck.



That's it, someone would need to realize, in 1939, that this is a flawed project and that the resources were better spent elsewhere.


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## fubar57 (Mar 29, 2019)

I think they realized that in August, '39

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## Clayton Magnet (Mar 29, 2019)

P-39 Expert said:


> Just think of it, a logistic dream standardizing on one fighter with one type armament.


The P-51 with Hispano Mk.II's? sounds great!


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## pbehn (Mar 29, 2019)

Clayton Magnet said:


> The P-51 with Hispano Mk.II's? sounds great!


In 1939 that sounds wonderful.

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## XBe02Drvr (Mar 30, 2019)

P-39 Expert said:


> We could have had 77000 P-51s (in addition to the 15000 that were actually produced) for what was paid for the 52000 other fighters.


Or why not just cancel all US designs and build 100,000 Spitfires and Hurricanes for the price??
😁😁😁😁😁😁😁😁😁😁😁😁😁


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## GrauGeist (Mar 30, 2019)

Or for that matter, let's everybody just buy Bf109s...

Bf109s for everybody! You get a Bf109, he gets a Bf109, they get a Bf109 the whole world gets a Bf109!!

Except Japan. Japan didn't like the Bf109. They're not a team player...

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## P-39 Expert (Mar 30, 2019)

gjs238 said:


> That's it, someone would need to realize, in 1939, that this is a flawed project and that the resources were better spent elsewhere.


The Russians are glad you weren't in charge of production.

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## fubar57 (Mar 30, 2019)

The Russians weren't at war yet so wouldn't have cared about the aircraft

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## P-39 Expert (Mar 30, 2019)

Shortround6 said:


> A little less hyperbole if you please.
> 
> I know (or really hope) you are being sarcastic but let's face it. The P-39 didn't meet the advertising hype that Bell had built up around it (more than a few other planes didn't either).
> It was one of two fighters the US could have in production in large numbers in 1941/42.
> ...


All those planes had multiple contracts, just build out the initial contract and move on to the P-51. Same Allison engine, same propellers, North American is part of GM so facilities and $$ shouldn't be a problem.

You'll also need to keep producing one of either the P-39 or P-40 to provide to our allies since you don't want to be giving the Russians a plane with the range of the P-51. And you'll need that plane to use until the P-51 becomes operational in July '42. In July '42 neither the P-38 nor the P-47 are in combat yet.


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## Shortround6 (Mar 30, 2019)

P-39 Expert said:


> All those planes had multiple contracts, just build out the initial contract and move on to the P-51. Same Allison engine, same propellers, North American is part of GM so facilities and $$ shouldn't be a problem.




Ir would take between 4 and 8 months to retool the factory and get the production back up to the same numbers of planes per month. 

It isn't always about the money. 

.

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## pbehn (Mar 30, 2019)

P-39 Expert said:


> All those planes had multiple contracts, just build out the initial contract and move on to the P-51. Same Allison engine, same propellers, North American is part of GM so facilities and $$ shouldn't be a problem.
> 
> You'll also need to keep producing one of either the P-39 or P-40 to provide to our allies since you don't want to be giving the Russians a plane with the range of the P-51. And you'll need that plane to use until the P-51 becomes operational in July '42. In July '42 neither the P-38 nor the P-47 are in combat yet.


That is pretty much what happened wasn't it?


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## Milosh (Mar 30, 2019)

P-39 Expert said:


> All those planes had multiple contracts, just build out the initial contract and move on to the P-51. Same Allison engine, same propellers, North American is part of GM so facilities and $$ shouldn't be a problem.
> 
> *You'll also need to keep producing one of either the P-39 or P-40* to provide to our allies since you don't want to be giving the Russians a plane with the range of the P-51. And you'll need that plane to use until the P-51 becomes operational in July '42. In July '42 neither the P-38 nor the P-47 are in combat yet.



P-40 as it is the more versatile a/c.

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## gjs238 (Mar 30, 2019)

Milosh said:


> P-40 as it is the more versatile a/c.


...and less risky.
Assuming that the P-39 project is cancelled before production begins, and the P-40 is chosen as the interim aircraft of choice, can Curtis produce enough P-40s or are other avenues of production needed, such as the British Purchasing Commission attempted with NAA?


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## fubar57 (Mar 30, 2019)

As with other failing companies, Bell could have been tooled up to make P-40s

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## GrauGeist (Mar 30, 2019)

fubar57 said:


> As with other failing companies, Bell could have been tooled up to make P-40s


Bell would soon be building B-24s and B-29s, but had it's hands full with the YFM, XFL, XP-52 and P-39 before the war and ended up with several more irons in the fire by 1941.

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## Shortround6 (Mar 30, 2019)

fubar57 said:


> As with other failing companies, Bell could have been tooled up to make P-40s




Curtiss was the only company to make P-40s. No other company, failing or otherwise, built P-40s. 

Curtiss was given a contract to build P-47s and made a hash of it. 

I am not sure that _any_ USAAF fighter was made by another "company" in large numbers. Navy fighters yes.

Several of the companies making USAAF fighters opened entirely new plants , hundreds if not thousands of miles from the original plant. 

Bell was given a contract for 13 YP-39s April 27th 1939,

Bell was given a contract for 80 P-39/P-45s Aug 10th 1939, so production tooling would have started not long after. 

Then come the French and British orders for 675 aircraft by June of of 1940.

ON Sept 14th 1940 the Army orders 623 additional Airacobras and that pretty much seals things. 

In Jan 1940 Bell had 1200 employees, In Jan 1941 they had 5000, AS of Dec 31st 1940 Bell had delivered 24 Aircraft total , that includes 11 YFM-1, YFM-1A and YFM-1B aircraft. 
BY Jan 1st 1942 Bell will have over 10,000 employees and a new factory at Niagara Falls. 

Switching factories around sounds good on paper years later. It might not have worked out so well in practice. 

I would note that many sources claim that Republic got orders for the P-43 only to help enlarge the factory and keep the work force together. 
There were four contracts for P-43s.
The first contract for 13 YP-43s on March 12th 1939, first plane delivered Sept 1940.
Now in Sept of 1940 all work stopped on the P-44 Rocket ( A P-43 with a P & W R-2180 engine) and work not only started on the P-47B but Republic was given a contract for 733 P-47s with R-2800 engines.
Since this plane only existed on paper Republic was also given a contract for 54 production P-43s in late 1940. This was followed by a separate contract for 80 additional P-43As. 
On May 6th the first flight is made by the XP-47B.
On June 30th 1941 Republic gets a contract for 125 P-43A-1s for lend lease to China. 
Dec 21st 1941 the first "production" P-47B is rolled off the line. Changes are needed.
In Jan 1942 1050 P-47Ds are ordered from the Evansville Indiana Plant (either unbuilt at this time or just starting construction) and 354 P-47Gs are ordered from Curtiss at Buffalo NY.

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## fubar57 (Mar 30, 2019)

I was referring to Post #604, ".........Assuming that the P-39 project is cancelled before production begins............."


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## Shortround6 (Mar 30, 2019)

Well, you need some Grand Overlord of Allied Aircraft Production (GOAAP for short) to make this decision in between May of 1939 and May 1940. 

Of course at this time the US is not part of the "allies". 

Even with the order in Aug of 1939 for 80 P-39s Bells financial future was in jeopardy. The French Gave Bell a check for 2 million dollars in the spring of 1940 as a downpayment/advance on their order for 165/170 planes. 
The French thought they were ordering a 400mph (or 390mph) airplane and not a 350-360mph airplane (P-40).

Not sure what the reaction would be to being told the P-39 wonder plane was being canceled and everybody would have to make do with P-40 Tomahawks. 

The US might be able to write off their 80 plane order if canceled early enough, once Bell has the French order things get tougher and once the British join in with their 505 plane order Bell is committed. 

Most US aircraft companies in 1938-1940 were actually pretty small in floor space and employees. 

North American was well known to the British due to them having started ordering Harvard MK I trainers in 1938. Noorduyn of Canada had licenced the AT-6 and started building them in early 1940.


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## pbehn (Mar 30, 2019)

I don't know how the subject is so controversial. The USA wasn't at war until the December 1941. Many preparations may have been made but they are different to being at war. From the invasion of Russia the conduct of USA military procurement was completely logical. The P-39 and P-40 both had the advantage of being there at the start but were supplanted by other designs more in keeping with what was needed. From a standing start as a design for a foreign government the P-51/Mustang was adopted progressively over the P-39 and P-40 because it was a better design with more utility. The P-39 had just been rejected and being packed off to Russia when the Mustang Mk I first arrived in UK. Then the Spitfire MK IX arrived, the Typhoon was getting better, P-38, P47 etc. The P-39s chance to shine in Europe was at the very start and it missed that chance.


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## Shortround6 (Mar 30, 2019)

I missed something earlier when I said that the P-39 and P-40 were not what the Army wanted in 1939/40/41 but what they could get. 

What I missed was that the Army didn't _know _that what it "wanted" wasn't necessarily what it _needed._ 

Which lead to both the P-38 and P-47 not being suitable for long range bomber escort in 1943 (2-3 years _after_) they were first ordered. 

Complaints about the short range of the P-47 will be filed in the circular bin, until somebody explains how a fighter with roughly twice the range of most European fighters of the time Ion internal fuel) is considered "short ranged". Yes it was not what was needed to escort B-17/24s in Europe but we are back to what was needed after several years of war vs what they thought they needed before the war (for the US) started. P-47 being ordered during the BoB.

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## pbehn (Mar 30, 2019)

Shortround6 said:


> I
> 
> Complaints about the short range of the P-47 will be filed in the circular bin, until somebody explains how a fighter with roughly twice the range of most European fighters of the time Ion internal fuel) is considered "short ranged". .


Well you can have planes with engines and arms, even complete aerodynamic principles that didn't exist, transplanted into a different era what is the problem with a minor issue like range?


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## Ivan1GFP (Mar 31, 2019)

Hello All,
Seems like we are all attempting to make radical adjustments to history with what we know in hindsight.
How about we take a slightly different approach and adjust with knowledge available at the time.

What was really so WRONG with the P-39 that made it less than successful except in Soviet service?
One problem was reliability which was solved after some time.
The other problem was that the Center of Gravity migrated too far aft and the aircraft became unstable as disposable loads were expended.

The Soviets had a different philosophy for fighter armament. 
Their preference was for guns close to the centerline and their fighters tended to be more lightly armed than other Allied fighters.
They had very efficient machine guns and were satisfied with just one or two fuselage mounted MG with a motor cannon.
They removed the wing guns from most of their Airacobra.

Americans seem to want every piece of equipment onboard every aircraft and end up with some pretty heavy aircraft.
Some items such as the mooring kit and engine tool kit and other such service items probably did not need to be carried on the aircraft.
The choice of the Soviets to remove wing armament probably would not have been satisfactory because it would have only left three guns all with fairly low cyclic rates, so to make up for that, I believe it would have been a good idea to go back to the armament arrangement of the P-39C and restore the two synchronized .30 cal MG in place of the wing guns.
The armour for the propeller gearbox could be removed to partially compensate for the weight.

In addition, to help adjust the CoG forward, standard load for the .50 should be adjusted to 270 rounds per gun as the Soviets did with their Airacobra. The Radio could be moved to the area behind the cockpit above the engine without significantly affecting visibility from the cockpit. It would only block visibility into the aft fuselage because of where the pilot sits.
To reduce weight, the armour plate from the Turnover Bulkhead could be removed; The bulk of the engine is behind the pilot for protection. The armour plate for the oil tank perhaps should be removed as well because of the large moment arm it has from the aircraft CoG.

So far, this is the minimally invasive approach.
From test reports, it appears that the CoG of the Airacobra doesn't really migrate very much even on the early versions.
A heavily loaded Airacobra tends to have a CoG at around 25% MAC.
A normal loaded Airacobra tends to have a CoG at around 28% MAC.
An Airacobra without disposable loads in place has CoG at around 30% MAC.
This migration of CoG isn't very great so there is probably something else going on.
Perhaps the airfoil being used has a very odd pitching moment?
The problems in handling seem to be related to lack of stability due to CoG being too far aft.
If this is the case, then perhaps it would have made sense to redesign the outer wing panels with greater sweep as was done on the Ilyushin IL-2 when a rear gunner was added and changed the CoG.
It would also be the chance to go to a more conventional non-symmetric airfoil and possibly increase the wing area a bit to compensate for the increased weight over that of the prototype aircraft.

Thoughts?
- Ivan.


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## GrauGeist (Mar 31, 2019)

There is never going to be a simple conclusion to the P-39 - seriously.
The aircraft had it's merits and it had it's shortcomings, like ALL aircraft will have.

I suspect, though, that the opinion of P-39 in American service may be along the lines of the F2A Buffalo, in retrospect.
The American pilots of the F2A were not schooled in the current day's tactics. They were also not combat veterans so when they hit the IJN fighters head-on, they had a steep learning curve ahead of them.
This too, may hold true to the USAAC pilots, who were thrust into the P-39's cockpit and given a crash-course.

The reason why I am touching on this, is because that's exactly what happened to my great-uncle, who was trained in the P-36, love his P-36 and was forever hateful that his P-36 sat idle on an auxiliary field on Oahu, 7 December 1941, lacking ammunition and fuel.
Shortly after Pearl, his P-36 was traded for a P-39 and he was rushed through training on it and he hated the Airacobra with a passion. He always stated that he would have gladly gone up to face any and all Japanese opponents in his P-36 than with a P-39...fortunately for him, he had an opportunity to train on the P-38, which he jumped at the chance and ended up flying them in the PTO for the duration.

So I am left to wonder if the characteristics of the P-39 ran contrary to his comfort zone, being experianced in the well-performing P-36 and then shoved into the cockpit of the unknown P-39, tending to cloud his judgement of the Airacobra to a certain degree.

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## XBe02Drvr (Mar 31, 2019)

pbehn said:


> Well you can have planes with engines and arms, even complete aerodynamic principles that didn't exist, transplanted into a different era what is the problem with a minor issue like range?


"Don't need THAT much range; the bombers will always get through. What we need is a high altitude air superiority fighter/interceptor"


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## P-39 Expert (Mar 31, 2019)

Milosh said:


> P-40 as it is the more versatile a/c.


How so? P-40 was slower, climbed slower, had a lower ceiling and about the same range. They both had one centerline external store.


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## P-39 Expert (Mar 31, 2019)

GrauGeist said:


> There is never going to be a simple conclusion to the P-39 - seriously.
> The aircraft had it's merits and it had it's shortcomings, like ALL aircraft will have.
> 
> I suspect, though, that the opinion of P-39 in American service may be along the lines of the F2A Buffalo, in retrospect.
> ...


Your great uncle's P-36 weighed 5700#. His P-39 was a ton heavier and was 50mph faster.


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## P-39 Expert (Mar 31, 2019)

Ivan1GFP said:


> Hello All,
> Seems like we are all attempting to make radical adjustments to history with what we know in hindsight.
> How about we take a slightly different approach and adjust with knowledge available at the time.
> 
> ...



See above.


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## fubar57 (Mar 31, 2019)

P-39 Expert said:


> Your great uncle's P-36 weighed 5700#. His P-39 was a ton heavier and was 50mph faster.


On the plus side, his uncle was there, had first hand experience, knew what he was talking about and wasn't some kind of "expert"

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## pbehn (Mar 31, 2019)

fubar57 said:


> On the plus side, his uncle was there, had first hand experience, knew what he was talking about and wasn't some kind of "expert"


Can you give me a hand with this armour guns and ammo, we are putting them in and out again.


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## DerAdlerIstGelandet (Mar 31, 2019)

I thought I walked into the flat earth thread here for a sec...

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## P-39 Expert (Mar 31, 2019)

fubar57 said:


> On the plus side, his uncle was there, had first hand experience, knew what he was talking about and wasn't some kind of "expert"


Did not, in any way, mean to disparage the great uncle's brave military service nor his recollection of the past. Just stating my opinion. He, like the P-39/40 was there in '42 and deserves a bigger place in history.


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## Shortround6 (Mar 31, 2019)

P-39 Expert said:


> How so? P-40 was slower, climbed slower, had a lower ceiling and about the same range. They both had one centerline external store.



P-40s starting with the F (not sure on Es) had 3 external stores points. In fact I am not sure about some of the earlier ones. The points under the wings were only rated for 100-150lb but they were there. Some of the "strippers" had the underwing points removed but they were added back in first with a 500lb rating and then with a 1000lb per wing rating. 



> *Weight. Soviets removed the usless .30 caliber wing guns.*



Hmmm. 1/2 the armament of a SPitfire or Hurricane during the BoB. Yep, must be useless. or Twice the firepower (more than twice) of a Zero or 109 E/F once they had run out of cannon shells. So again, utterly useless. Or let's imagine the fantastic performance of either the Zero or the 109 if those useless guns had been taken out?? granted it is only two guns and ammo but then both of these planes are almost a ton lighter than P-39 to begin with so the percentage weight difference is closer than the 2/4 ratio. 



> *Generally considered more reliable than the P-40 in terms of TBO, daily readiness.*



Got any proof of this? and comparing which models? Russians did have a lot of trouble with the first Tomahawks. 



> *The .30s were the biggest problem of the P-39 and were not used on any other production US fighter. *



Hmmm, just what the heck were in the wings of the P-40, P-40B and P-40C??

The outer two guns in the Mustang Is were .303s so technically you are correct (that and the Mustang I was a British fighter produced in the US) 

The US .30 was used as a defensive gun on thousands of US single engine strike aircraft (mostly Dauntlesses ) and several thousand A-20 attack bombers. 

Perhaps those crews should have left the .30s on the ground and depended on the better climb and maneuverability of the planes without them? 



> * Climb and ceiling are greatly increased with only a small reduction in firepower. This is applicable to the early P-39s (D through M). The N climb and ceiling were just fine even with the wing guns/nose armor, but removing them would just make it better.*



Just imagine the climb and ceiling of a Spitfire if you took out the four useless .303 guns in the wings 

Who needs a MK IX, just take 200-220lbs of guns and ammo out of a MK V and get 6-700fpm more climb and several thousand feet more altitude. 
Who needs a P-51, just jam 40-50 gallons of fuel into the wings of MK V Spit instead of the 4 machine guns and Presto, a long range bomber escort.

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## wuzak (Mar 31, 2019)

Shortround6 said:


> Got any proof of this? and comparing which models? Russians did have a lot of trouble with the first Tomahawks.



That may have been a problem with the long nose V-1710.

Which is teh only difference which would make the P-40 less reliable than the P-40, as far as I can tell.


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## Glider (Mar 31, 2019)

I have just found a reference to an article written on 1st March 1940 in a highly respected aviation magazine of the period called _The Aeroplane _about what they thought of the claims made by Bell.
The article dismisses as _absurd the various figures published by Bell. In particular a maximum speed of 400mph, a cruising speed of 325mph, an operating altitude of over 36,000ft, a cruising range over 1000 miles on a fully loaded weight of approx. 6,000ib and a wing loading of 28.3 lb per sq ft._ This weight the article claimed, _is simply impossible with an engine of this size, a particularly long drive shaft and its mounting, the tricycle undercarriage, with the armament specified, with the range and wing loading specified._
The article continued 'T_he manufacturer must have discovered some wonderful law of nature if they can build an aeroplane that weighs no more than a Hawker Hurricane yet has more horse power, radiators in the wings, about 300lb more fuel, a cannon, a tricycle undercarriage, a long extension shaft and a constant speed airscrew'._
The author then put his finger on the core issue.
_'The idea seems to be to get a spectacular top speed for advertising purposes at the expense of everything else. That may be all right in America but when they are exported for war, they will have to be modified to make them lethal_.
The summary was equally scathing categorising the Airacobra as '_a thoroughly ill conceived aeroplane, taken in general and in detail_'. In a final flourish _As a serious fighter the Bell is all wrong. We trust the British Purchasing Commission in the USA will not be hoodwinked into placing an order._

We can take from this that the author wasn't a fan but he got a lot more right than he got wrong. If someone had listened to him and at least put some effort into checking the claims made by Bell a lot of time and effort would have been saved. 
When you also consider that the writing style of the time was to be very polite and matter of fact this was really strong language.

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## Shortround6 (Mar 31, 2019)

There was quite a bit of trouble with the Long nose P-40s because they were delivered with a generator much larger than originally specified and the drive system was not up to the load and broke often. replacement drives were supplied but not in enough quantity but the problem was not resolved until both a new generator drive and smaller generators (somewhere between the original specification and the first supplied generators) showed up. This was pretty well sorted out by the time the P-40E and later showed up. 

Russian aircraft were also rather difficult to maintain at least in the first year or two. Instead of electrical or hydraulic actuation of flaps/landing gear and other systems they used pneumatics (air pressure) in many of their fighters, which while lightweight, tended to leak (a lot). leading to aircraft parked overnight sitting on their bellies in the morning and other problems.

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## GrauGeist (Mar 31, 2019)

P-39 Expert said:


> Your great uncle's P-36 weighed 5700#. His P-39 was a ton heavier and was 50mph faster.


For a closer comparison:
His P-36A weighed 4,550 clean and 5,650 loaded with a speed of 313mph at 8,000 feet.
His P-39D weighed 5,400 clean and 7,500 loaded with a speed of 355 at 10,000 feet.

All those numbers really mean nothing unless you put it into context. He qualified in the P-36 and had quite a few hours logged in it. It was tolerant, nimble and handled very well, which gives a pilot a certain measure of confidence in what they can (and cannot) do with their machine.
Now, he's removed from that comfort zone and put into an entirely different machine that has an entirely different set of rules and he had to discard his P-36 mindset if he was going to live by the Airacobra's rules.
And he didn't like that.

And since we were comparing his P-36 to a P-39, let's see how the P-39 looks compared to a P-38 (I understand that he qualified with the P-38F): Which was 12,250 clean and 15,900 loaded and roughly the same speed at the P-39D at 10,000 feet.

So at nearly 7 tons heavier and roughly the same speed at 10,000 feet, it would **almost** seem that the P-39D was the better deal...

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## Ivan1GFP (Mar 31, 2019)

Hello P-39 Expert,



P-39 Expert said:


> Weight. Soviets removed the usless .30 caliber wing guns.



Lets go with what you are thinking for a bit and see where it leads.
The .30 Cal Wing guns weigh 94.9 pounds in total for all 4.
The standard load of ammunition for all 4 guns together is 78 pounds.
Loss of 172.9 pounds.
The Soviets also increased the ammunition load of their .50 cal cowl guns from 200 to 270 rounds.
Ammunition weight goes from 129 pounds to 174 pounds.
Gain of 45 pounds.
for a net loss of 127.9 pounds of armament & ammunition.

So what you are claiming is that 127.9 pounds of weight difference would significantly increase performance?
I don't believe that is a reasonable conclusion.

As for no other US Fighter using the .30 caliber, Shortround6 already commented about early P-40 through P-40C.
Note that the P-36 used them as well.
I do not believe that the US Army would have accepted a 37 mm gun and two synchronized .50 cals as sufficient armament.
As for whether the .30 cal guns were effective, the Japanese and British took down an awful lot of aircraft with that kind of fighter armament.



P-39 Expert said:


> And had no effect on normal flight. In order to have any chance of "tumbling" the nose ammo had to be expended, then a vertical climb until near stalling speed, then pull back hard on the stick. To spin or "tumble" a plane had to stall first and the P-39 had excellent stall characteristics.



Your claim is contradicted by pilot reports. Although "Tumbling" was pretty hard to achieve and did require a vertical climb and specific control inputs, a departure and spin was possible in other flight conditions with the CoG too far back. The P-39 had excellent stall characteristics if the CoG was far enough forward but was much less predictable and not very suitable for aerobatics if that was not the case.



P-39 Expert said:


> Actually the minimally invasive approach would be for the crew chief at forward bases to remove the underpowered wing guns (and related equipment), the nose armor plate, and move the radios up from the tail cone for balance.



The problem with moving the radio as a field modification is that I don't believe there was enough test equipment out in the field to check for interference with other electrical components such as the engine's ignition system. Radios also tend to be fairly heavy and it would make more sense to have properly engineered brackets supporting them.

- Ivan.

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## Greg Boeser (Mar 31, 2019)

GrauGeist said:


> For a closer comparison:
> His P-36A weighed 4,550 clean and 5,650 loaded with a speed of 313mph at 8,000 feet.
> His P-39D weighed 5,400 clean and 7,500 loaded with a speed of 355 at 10,000 feet.
> 
> ...


P-36s in Hawaii on 7 Dec 1941 acquitted themselves very well, considering they were unprepared for battle, had to be prepared for combat between strike waves of the Japanese and the pilots had no previous combat experience. In a dogfight near Kaneohe NAS, four P-36s of the 46th PS tangled with nine Zeroes and lost only one plane while claiming two. (Japanese records show no losses, though one plane had to be scrapped on return to the carrier.) Another pair of P-36s caught some B5Ns as they were retiring and Lt Ken Brown flamed two, with only a single .30.


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## GrauGeist (Mar 31, 2019)

Lt. Rasmussen's uniform that morning consisted of purple pajamas and a .45

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## XBe02Drvr (Apr 1, 2019)

Shortround6 said:


> Instead of electrical or hydraulic actuation of flaps/landing gear and other systems they used pneumatics (air pressure)


Those Fokkers I worked on at the commuter had pneumatic landing gear, brakes and steering, and were an absolute PITA in our northcountry winters. Fortunately they had bulletproof downlocks, so no unauthorized sitdowns.


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## XBe02Drvr (Apr 1, 2019)

GrauGeist said:


> So at nearly 7 tons heavier


HUH? Try 4 tons heavier and twice the horsepower; sure looks like a better deal in my book. And if those turbos stay healthy, altitude's not a problem either. Keep your speed up, boom 'n zoom, hell combat could almost be fun!
Cheers
Wes


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## XBe02Drvr (Apr 1, 2019)

Ivan1GFP said:


> I don't believe there was enough test equipment out in the field to check for interference with other electrical components


And you most likely are going to change the length of the antenna feedline. If not tuned properly, standing waves in the feedline can eat up as much as 2/3 of your transmitter power.


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## GrauGeist (Apr 1, 2019)

XBe02Drvr said:


> HUH? Try *4 tons heavier* and twice the horsepower; sure looks like a better deal in my book. And if those turbos stay healthy, altitude's not a problem either. Keep your speed up, boom 'n zoom, hell combat could almost be fun!
> Cheers
> Wes


Well, I guess my math is not as great as yours.
P-39D clean: 5,400 pounds
P-38F clean: 12,250 pounds.
That looks to be almost 7 tons difference.

P-39D loaded: 7,500 pounds.
P-38F loaded: 15,900 pounds.
There appears to be about 8 tons difference.

But I suppose counting on fingers can be confusing...


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## XBe02Drvr (Apr 1, 2019)

GrauGeist said:


> But I suppose counting on fingers can be confusing..


Well maybe the ROE is changed. I was taught that our quirky Anglo Saxon measuring system considers a ton to be 2000 pounds, but then again, I've seen folks who jump back and forth between Metric and SAE a lot speak of it as if it were 1000 pounds. Maybe it's changed and hasn't penetrated the rock I live under. Any case, I'm too drowsy-eyed to think straight at this hour. I can hear a pillow calling.
Cheers,
Wes

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## wuzak (Apr 1, 2019)

1 short ton (US ton) is 2,000lb.
1 long ton (UK ton) is 2,240lb.
1 metric tonne is 2,204.6lb.

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## Milosh (Apr 1, 2019)

GG, I think you need to recalculate. That is, cut your tonnes by half.

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## pbehn (Apr 1, 2019)

14 pounds = 1 stone
8 stones = 1 hundredweight
20 hundred weight = 1 ton

20 x 8 x 14 = 2,240 lbs 

Couldn't be any easier!

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## wuzak (Apr 1, 2019)

Nice and logical.

Not like the stupid
1,000 grams = 1 kilogram
1,000 kilogrames = 1 tonne
1,000 tonnes = 1 kilotonne

etc....

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## pbehn (Apr 1, 2019)

wuzak said:


> Nice and logical.
> 
> Not like the stupid
> 1,000 grams = 1 kilogram
> ...


11 meters = 36 feet which is why the English always lose a penalty shoot out.

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## drgondog (Apr 1, 2019)

XBe02Drvr said:


> "Don't need THAT much range; the bombers will always get through. What we need is a high altitude air superiority fighter/interceptor"


I suspect tongue firmly in cheek. That said, Arnold was well aware during the Spanish Civil War, Blitzkrieg and then Battle of Britain - that the bomber frequently did not get through. The primary issues for both the Brits and US were a.) a single engine fighter with the fuel weight fraction necessary to extend to target range could not compete with the interceptors of the day, and b.) that multi engine aircraft with the fuel fraction potential, would be equally handicapped, but the only technologically feasible (at that time) escort solution. He personally changed the Kilner-Lindbergh and Emmons Report recommendations of low priority for long range (1500 miles) fighter to first, was his own vision that a 'back up' contingency that B-17 high speed and altitude would not be enough to support the Army Air Force War Plans Directive in the future. 

Three factors in early-mid 1942 changed the game. Rolls-Royce took the initiative to push the hybrid Merlin 60 series engine/Mustang graft. NAA was finally supported by Arnold and the Planning/Military Requirements Divisions to recognize the Allison Mustang as superior to both the P-40 and P-39 - and run over Echols at MD who recommended converting Mustang production to B-25s. Arnold personally met with top RAF officials along with Winant and Hitchcock in May 1942 to get a briefing on the 'hybrid'. At that moment in time Packard was well on its way to production tooling for the 1650-3, but RAF/and the BAM were already discussing possible license production of NA-91 w/Merlin 65 in Britain. 

The political maneuvering between AAF-HQ, AAF-MD, NAA, GM, Allison and RAF/BAM as the 'projects' unfolded in May-June 1942 when AAF awarded NA-101 conversion of two NA-91 airframes from Allison to Packard 1650-3 were intense (understatement).

Another extremely important intiative by AAF was the Long Range Extension Program initiated in March/April 1942 which embraced not only external combat tank integration into the contractor specifications but also mandated increasing internal fuel. Lockheed was already in compliance with external rack/fuel feed plumbing in the P-38, NAA had already integrated the same into the forthcoming A-36 and was testing in NA-83 AM118 in May. Republic figured out what was required to install the plumbing and racks as kits for P-47C/D through the P-47D-11 but they were very labor and time intensive throughout 1943 after first testing in June 1943.

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## DerAdlerIstGelandet (Apr 1, 2019)

pbehn said:


> 11 meters = 36 feet which is why the English always lose a penalty shoot out.



I thought that was because they were playing ze Germans...

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## Peter Gunn (Apr 1, 2019)

GrauGeist said:


> Well, I guess my math is not as great as yours.
> P-39D clean: 5,400 pounds
> P-38F clean: 12,250 pounds.
> That looks to be almost 7 tons difference. *(Actually 6,850 lbs difference)*
> ...


Hmm...

Going by what I thought was a U.S. ton (2,000 lbs)

5,400 = 2.70 tons
12,250 = 6.125 tons
*6.125 - 2.7 = 3.425 tons difference*

7,500 = 3.75 tons
15,900 = 7.95 tons
*7.95 - 3.75 = 4.20 tons*

I could be wrong, math is not my strongest ability...

Cheers

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## wuzak (Apr 1, 2019)

drgondog said:


> At that moment in time Packard was well on its way to production tooling for the 1650-3, but RAF/and the BAM were already discussing possible license production of NA-91 w/Merlin 65 in Britain.



I believe there was also a proposal to import Mustangs to Britain and install Merlins at a conversion centre, possibly run by Rolls-Royce.

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## pbehn (Apr 1, 2019)

DerAdlerIstGelandet said:


> I thought that was because they were playing ze Germans...


It was a never ending discussion in German bars. Whether a penalty is 11 meters or 12 yards and why the English always miss lol. It is obviously 12 yards, the goal is 8 yards by 8 feet, and the boxes are 6 yards and 18 yards with a 10 yard radius on the penalty spot and centre circle. Only the penalty spot a metric measurement by pure chance.

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## Clayton Magnet (Apr 1, 2019)

pbehn said:


> 14 pounds = 1 stone
> 8 stones = 1 hundredweight
> 20 hundred weight = 1 ton
> 
> ...


Universal metric acceptance can't come soon enough

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## fubar57 (Apr 1, 2019)

Just the super-power countries not using metric now; U.S. of A, Myanmar and Liberia

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## pbehn (Apr 1, 2019)

Clayton Magnet said:


> Universal metric acceptance can't come soon enough


I know the imperial system but never actually used it from the age of about 8. However I worked in the oil gas industry which is still governed by API specifications so even within Europe tally lists are produced in metric and imperial for weight and length. There may be some issues if they decide to change the gauge on railways though.


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## special ed (Apr 1, 2019)

I have for years told people, if we had been born with six fingers on each hand and six toes on each foot, the world would use the imperial system. I then point out twice as many numbers are evenly divisible into 12 as 10.


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## pbehn (Apr 1, 2019)

special ed said:


> I have for years told people, if we had been born with six fingers on each hand and six toes on each foot, the world would use the imperial system. I then point out twice as many numbers are evenly divisible into 12 as 10.


If you buy a ton of anything, one tenth is too heavy for anyone to lift, the practical limit is 1/20th of a ton which is 1 hundredweight. Most imperial measures evolved because of practical use, which is pragmatic but becomes difficult to impossible for calculations.


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## special ed (Apr 1, 2019)

Do you mean measuring horses by how many hands high?


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## pbehn (Apr 1, 2019)

special ed said:


> Do you mean measuring horses by how many hands high?


Things like that. An acre was based on how much an average horse could plough in a day, so if you know an acreage you know how many horses/days you need to plough it. A hand is used to measure horses because a foot is too big, one hand is four inches or 1/3 of a foot. It is the same in foot measurements using barleycorns which are 1/3 of an inch.


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## Peter Gunn (Apr 1, 2019)

All of the above is well and good, but what if there is an 'R' in the month?


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## fubar57 (Apr 1, 2019)

Peter Gunn said:


> All of the above is well and good, but what if there is an 'R' in the month?


Stay away from shellfish......or strawberries, I can't remember which


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## pbehn (Apr 1, 2019)

fubar57 said:


> Stay away from shellfish......or strawberries, I can't remember which


Obviously Shellfish, strawberries has two "R"s in it. Please pay attention it is perfectly simple.


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## special ed (Apr 1, 2019)

In the US, for a great many years land was measured with a chain of exact length which laid on the ground, but since the use of transits and optical measuring, the property lines of old established land are being moved. Differing measuring systems have always caused difficulty. Rifles of US and UK manufacture have the rear sites marked in yards, while European rifles were in meters, and Russian rifles were in Arshins.


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## special ed (Apr 1, 2019)

Now that everyone has taken the bait, maybe we can stop beating this dead horse. If P-39's were great, we would see a lot more of them as collectibles. Instead, we see P-40's,P51's, F6f"s, F4U's, P-38's, Spitfires, and so on. There are a few more P-39's than MS-406's though.


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## pbehn (Apr 1, 2019)

special ed said:


> In the US, for a great many years land was measured with a chain of exact length which laid on the ground, but since the use of transits and optical measuring, the property lines of old established land are being moved. Differing measuring systems have always caused difficulty. Rifles of US and UK manufacture have the rear sites marked in yards, while European rifles were in meters, and Russian rifles were in Arshins.


Same in UK, an acre is a chain (22 yards) x a furlong 220yards (furrow length). A horse or pair of oxen need a rest after ploughing a furrow. In a game of Cricket the wickets are 1 chain apart.


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## special ed (Apr 1, 2019)

Isn't that akin to furlongs per fortnite?


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## special ed (Apr 1, 2019)

I'm sorry. I've been a BAD boy. It's time for my treatment now.


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## pbehn (Apr 1, 2019)

special ed said:


> Isn't that akin to furlongs per fortnite?


Don't go there, bi-weekly and bi-monthly are the same thing, fortnightly.

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## swampyankee (Apr 1, 2019)

special ed said:


> In the US, for a great many years land was measured with a chain of exact length which laid on the ground, but since the use of transits and optical measuring, the property lines of old established land are being moved. Differing measuring systems have always caused difficulty. Rifles of US and UK manufacture have the rear sites marked in yards, while European rifles were in meters, and Russian rifles were in Arshins.


Until the middle third of the 20th Century, British inches and US inches were different.


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## special ed (Apr 1, 2019)

Is that only in the bedroom?

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## swampyankee (Apr 1, 2019)

special ed said:


> Is that only in the bedroom?



Obviously, American inches were larger, except in Texas


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## pbehn (Apr 1, 2019)

swampyankee said:


> Obviously, American inches were larger, except in Texas


Ive got twelve inches, but I don't use it as a rule.

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## Ivan1GFP (Apr 1, 2019)

pbehn said:


> 14 pounds = 1 stone
> 8 stones = 1 hundredweight
> 20 hundred weight = 1 ton
> 
> ...



Hmmmm.... So a Hundred Weight doesn't really have a "hundred" of ANYTHING.....

Makes perfect sense!

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## XBe02Drvr (Apr 1, 2019)

fubar57 said:


> Just the super-power countries not using metric now; U.S. of A, Myanmar and Liberia


Guess that means we've got an uphill battle ahead, freeing the world from the the tyranny of metricism, but we know we can rely on our allies!

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## pbehn (Apr 1, 2019)

Ivan1GFP said:


> Hmmmm.... So a Hundred Weight doesn't really have a "hundred" of ANYTHING.....
> 
> Makes perfect sense!


I do wish people would pay attention, a hundred weight has 112 pounds that's why its called a hundredweight.


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## XBe02Drvr (Apr 1, 2019)

special ed said:


> Now that everyone has taken the bait, maybe we can stop beating this dead horse.


AMEN

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## Peter Gunn (Apr 1, 2019)

pbehn said:


> I do wish people would pay attention, a hundred weight has 112 pounds that's why its called a hundredweight.


At that point, is it a 'Royal' Fizzbin or just a regular Fizzbin?


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## XBe02Drvr (Apr 1, 2019)

special ed said:


> Now that everyone has taken the bait, maybe we can stop beating this dead horse. If P-39's were great, we would see a lot more of them as collectibles.


AMEN!


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## pbehn (Apr 1, 2019)

Peter Gunn said:


> At that point, is it a 'Royal' Fizzbin or just a regular Fizzbin?


Obviously a long Fizzbin, a short hundredweight has 100 pounds.


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## Peter Gunn (Apr 1, 2019)

pbehn said:


> Obviously a long Fizzbin, a short hundredweight has 100 pounds.


My bad, thanks for the enlightenment.

Except how many Fizzs' in a bin?


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## fubar57 (Apr 1, 2019)

Am I ever glad I went to England after the farthings and shillings had been dispensed with, crazy British money!!!!!


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## Ivan1GFP (Apr 1, 2019)

Peter Gunn said:


> My bad, thanks for the enlightenment.
> 
> Except how many Fizzs' in a bin?



Are y'all using the rules from Beta Antares or just the simplified ones that Kirk was using?

- Spork.


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## pbehn (Apr 1, 2019)

fubar57 said:


> Am I ever glad I went to England after the farthings and shillings had been dispensed with, crazy British money!!!!!


Well there were 12 pennies in a shilling and 20 shillings in a pound, life must be hell for those who find it complicated. how do they tell the time with 60 seconds in a minute 60 minutes in an hour and 24 hours in a day? And lets not even consider the 360 degrees in a circle.

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## Ascent (Apr 1, 2019)

If your money is decimal when everything else is imperial your heart is obviously not in it. When we used imperial units everything was imperial including the money.

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## pbehn (Apr 1, 2019)

Ascent said:


> If your money is decimal when everything else is imperial your heart is obviously not in it. When we used imperial units everything was imperial including the money.


For me they all changed over at about the same time late sixties early seventies.


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## wuzak (Apr 1, 2019)

swampyankee said:


> Until the middle third of the 20th Century, British inches and US inches were different.



Imperial measurements are now defined by their relationship to their metric equivalent.

So the inch is defined as 0.0254m.
1lb = ‪0.453592‬kg.

etc.


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## Milosh (Apr 1, 2019)

Now this has to be the hijack of all thread hijacks.

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## fubar57 (Apr 1, 2019)

Possibly a record for the number of posts before things went sideways


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## pbehn (Apr 1, 2019)

Before I put these bloody fuel tanks back in I want to know their weight in kilos.

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## DerAdlerIstGelandet (Apr 2, 2019)

Milosh said:


> Now this has to be the hijack of all thread hijacks.



And somehow I don’t mind...

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## KiwiBiggles (Apr 2, 2019)

DerAdlerIstGelandet said:


> And somehow I don’t mind...


Imperial measurements are definitely more interesting than the weight of a P-39's fuel tanks.

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## pbehn (Apr 2, 2019)

KiwiBiggles said:


> Imperial measurements are definitely more interesting than the weight of a P-39's fuel tanks.


Does anyone know the dimensions and weights of a 0.3" bullet in barleycorns grains and scruples?

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## Kevin J (Apr 2, 2019)

KiwiBiggles said:


> Imperial measurements are definitely more interesting than the weight of a P-39's fuel tanks.


You mean like 40D-26-32 figures?

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## pbehn (Apr 2, 2019)

Kevin J said:


> You mean like 40D-26-32 figures?


Not the same in metric is it, in France and Germany many still give the weight of a baby in pounds because in metric 3 kilos sounds weak.

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## Peter Gunn (Apr 2, 2019)

Milosh said:


> Now this has to be the hijack of all thread hijacks.


Beats the hell out of rehashing that clunky P-39 business, sorry, a little cranky after helping *pbehn* offload, onload rinse repeat the armor and guns on our test Cobra...

Oiy, me achin' back...

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## Peter Gunn (Apr 2, 2019)

Ivan1GFP said:


> Are y'all using the rules from Beta Antares or just the simplified ones that Kirk was using?
> 
> - Spork.


I usually use the simplified Kirk rules, (hey it IS Captain Kirk after all) but in this instance, I believe the Beta Antares full rules should be in effect.


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## pbehn (Apr 2, 2019)

Peter Gunn said:


> Beats the hell out of rehashing that clunky P-39 business, sorry, a little cranky after helping *pbehn* offload, onload rinse repeat the armor and guns on our test Cobra...
> 
> Oiy, me achin' back...


I dont want to worry anyone but I just found 6 bolts, 8 nuts and a retaining clip.

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## Shortround6 (Apr 2, 2019)

pbehn said:


> Does anyone know the dimensions and weights of a 0.3" bullet in barleycorns grains and scruples


AP, Ball, Tracer or incendiary?

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## pbehn (Apr 2, 2019)

Shortround6 said:


> AP, Ball, Tracer or incendiary?


I don't really know, but they are all good names for Imperial units anyway, 4 scruples = 1 incendiary 1 ball = 17 barleycorns

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## wuzak (Apr 2, 2019)

pbehn said:


> I don't really know, but they are all good names for Imperial units anyway, 4 scruples = 1 incendiary 1 ball = 17 barleycorns



But how many incendiaries in a ball?


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## pbehn (Apr 2, 2019)

wuzak said:


> But how many incendiaries in a ball?


Square root(Incendiary-ball)=AP

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## Peter Gunn (Apr 2, 2019)

pbehn said:


> I dont want to worry anyone but I just found 6 bolts, 8 nuts and a retaining clip.


Yeah, but did you find my car keys?


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## fubar57 (Apr 2, 2019)

I love this place

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## Shortround6 (Apr 2, 2019)

delete


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## Peter Gunn (Apr 2, 2019)

pbehn said:


> I don't really know, but they are all good names for Imperial units anyway, 4 scruples = 1 incendiary 1 ball = 17 barleycorns


I get the incendiary, ball and barleycorns... what the hell's a scruple?


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## pbehn (Apr 2, 2019)

Peter Gunn said:


> Yeah, but did you find my car keys?


Is that what they were, we used them as a spacer.


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## Peter Gunn (Apr 2, 2019)

pbehn said:


> Is that what they were, we used them as a spacer.


Great, well, you're driving to the 'Gentlemen's Club' then for beers after we lug those damn guns and armor... wait, are we putting that stuff back in or taking it out?

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## pbehn (Apr 2, 2019)

Peter Gunn said:


> Great, well, you're driving to the 'Gentlemen's Club' then for beers after we lug those damn guns and armor... wait, are we putting that stuff back in or taking it out?


They've been used to jack up an axle, nothing to do but drink beer from here on in, hop in.

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## Greg Boeser (Apr 2, 2019)

Bi-weekly = semi-monthly = fortnight.


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## pbehn (Apr 2, 2019)

Greg Boeser said:


> Bi-weekly = semi-monthly = fortnight.


One of the joys of the English language Japanese say Bi-weekly, most Europeans say bi-monthly while the brits sit in the middle saying "fortnight" Ive been in a meeting when it happened.

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## XBe02Drvr (Apr 2, 2019)

Peter Gunn said:


> Yeah, but did you find my car keys?


So those were yours? The pushbutton on the big plastic-headed one set off my neighbour's burglar alarm, and we couldn't shut it off, and she wasn't home and the cops showed up and the security company showed up, and we had a lot of explaining to do. I'll forward the bill to you. Also my lawyer's bill and the bill for the fine and court costs.
Cheers,
Wes

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## swampyankee (Apr 2, 2019)

All the bi/semi-weekly/monthly combinations exist for the sole purpose of confusing people.

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## pbehn (Apr 2, 2019)

swampyankee said:


> All the bi/semi-weekly/monthly combinations exist for the sole purpose of confusing people.


I hadn't even heard of semi monthly until today, I can use that to make things even clearer.


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## special ed (Apr 2, 2019)

Exactly. Just like putting "pre" in front of everything. Words mean things. Pre means before, so pre existing means before it exists, therefore what we really mean is "existing". Apply that to all words with pre. We really mean approved, drilled, etc. There are very few words in English that are valid with pre in front. --- Are we drifting far enough?

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## Shortround6 (Apr 2, 2019)

We can go into tri-weekly sailings, where the ship leaves one week and tries to make it back the next.

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## gjs238 (Apr 2, 2019)

drgondog said:


> ...and run over Echols at MD who recommended converting Mustang production to B-25s.


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## Peter Gunn (Apr 3, 2019)

XBe02Drvr said:


> So those we're yours? The pushbutton on the the big plastic-headed one set off my neighbour's burglar alarm, and we couldn't shut it off, and she wasn't home and the cops showed up and the security company showed up, and we had a lot of explaining to do. I'll forward the bill to you. Also my lawyer's bill and the bill for the fine and court costs.
> Cheers,
> Wes


OK, that's it sailor, we're not bringing you to the 'Gentlemen's Club' after we finish working on the Cobra wonder plane, besides, what kind of Navy do we have that they didn't teach you deck apes anything about button pushing?

As far as fees go, you'll be hearing from my attorneys, the famous law team of Dewey Cheetam and Howe.

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## XBe02Drvr (Apr 3, 2019)

Peter Gunn said:


> OK, that's it sailor, we're not bringing you to the 'Gentlemen's Club' after we finish working on the Cobra wonder plane, besides, what kind of Navy do we have that they didn't teach you deck apes anything about button pushing?


The panic button on that key sticks out so far, I'm surprised you haven't set off your own alarm just putting your keys in your pocket! Or are you just not telling, perhaps?
You couldn't drag me into the "0" Club if you tried! For you it might be just a letter in your personnel jacket if anyone noticed, but for me it would be a court martial for sure. Besides, I ain't inta talkin' couth like y'all ociffer dudes. "Quarter deck is quarter deck and lower deck is lower deck, and never the twain shall meet,"
Cheers
Wes

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## BiffF15 (Apr 3, 2019)

XBe02Drvr said:


> The panic button on that key sticks out so far, I'm surprised you haven't set off your own alarm just putting your keys in your pocket! Or are you just not telling, perhaps?
> You couldn't drag me into the "0" Club if you tried! For you it might be just a letter in your personnel jacket if anyone noticed, but for me it would be a court martial
> for sure. Besides, I ain't inta talkin' couth like y'all ociffer dudes. "Quarter deck is quarter deck and lower deck is lower deck, and never the twain shall meet,"
> Cheers
> Wes



Wes,

Sorry to break the news to you, but there no longer is an Officers or Enlisted Club in the USAF. It’s now called the All Ranks Club and is usually open only for special occasions.

Cheers,
Biff

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## XBe02Drvr (Apr 3, 2019)

BiffF15 said:


> Wes,
> 
> Sorry to break the news to you, but there no longer is an Officers or Enlisted Club in the USAF. It’s now called the All Ranks Club and is usually open only for special occasions.
> 
> ...


Thankfully, the Nav still has some respect for tradition! Least they did last time I checked, anyway. Rank miscegenation is still not approved as far as I know.


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## Ivan1GFP (Apr 3, 2019)

Our tech orders allowed us to use the Officers' Club but after a couple visits, we decided to hang out at the Chiefs' Club instead.
Service was better and friendlier and the food was the same.

- Ivan.

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## XBe02Drvr (Apr 3, 2019)

Ivan1GFP said:


> after a couple visits, we decided to hang out at the Chiefs' Club instead.


Our CPO club was a veritable lion's den. If one of us dixie cup sailors stuck our head in there, it was liable to get bitten off. That was their refuge after putting up with us all day.
There even was an Acey-Ducey club for 1st and 2nd class petty officers, but when I went there after I made 2nd, it was "suggested" that the club was for career sailors, and that, since I was known to be longing for civilian life, I should go back to the EM club with the rest of the brats. Turns out that club was the refuge of the black shoe minority, awash in a sea of airedales. Black shoes weren't making rank anywhere near as fast as airedales, and the resentment was deep seated.
Cheers,
Wes

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## BiffF15 (Apr 3, 2019)

XBe02Drvr said:


> Our CPO club was a veritable lion's den. If one of us dixie cup sailors stuck our head in there, it was liable to get bitten off. That was their refuge after putting up with us all day.
> There even was an Acey-Ducey club for 1st and 2nd class petty officers, but when I went there after I made 2nd, it was "suggested" that the club was for career sailors, and that, since I was known to be longing for civilian life, I should go back to the EM club with the rest of the brats. Turns out that club was the refuge of the black shoe minority, awash in a sea of airedales. Black shoes weren't making rank anywhere near as fast as airedales, and the resentment was deep seated.
> Cheers,
> Wes




That’s a big difference between the USN and the USAF. The hierarchy in the Navy is alive and well defined. We have some good friends/couple who are/were enlisted Navy. It took them a while to interact with me “normally”. Luckily I have a never ending supply of humor and sarcasm with which I greased the wheels of progress!

Cheers,
Biff


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## Peter Gunn (Apr 4, 2019)

XBe02Drvr said:


> The panic button on that key sticks out so far, I'm surprised you haven't set off your own alarm just putting your keys in your pocket! Or are you just not telling, perhaps?
> 
> *SNIP*
> 
> ...


I can neither confirm nor deny that any of this so called "button pushing" has ever taken place on my watch. And as far as my car keys, I'm sending both *you* and *pbehn* a bill for replacement keys and fobs. Since I can't get into my vehicle I've been stuck here at the Blue Parrot Bar and Grille for the last couple of days. Although I must say, the floor show is simply fabulous...

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## yulzari (Apr 4, 2019)

Ivan1GFP said:


> Our tech orders allowed us to use the Officers' Club but after a couple visits, we decided to hang out at the Chiefs' Club instead.
> Service was better and friendlier and the food was the same.- Ivan.


Same in the British Army. If given the choice go for the Sergeants Mess. Who do you think chooses the staff and victuals?

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## yulzari (Apr 4, 2019)

pbehn said:


> One of the joys of the English language Japanese say Bi-weekly, most Europeans say bi-monthly while the brits sit in the middle saying "fortnight" Ive been in a meeting when it happened.


The one I can never get my head around is 'next Friday'. Is that the next Friday you come across so, on a Wednesday, it would be this week's Friday or is it the Friday next week which is the 2nd Friday you get to? Don't get me started on 'Friday week'. I always have to confirm with the date. Have we digressed?

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## yulzari (Apr 4, 2019)

pbehn said:


> Does anyone know the dimensions and weights of a 0.3" bullet in barleycorns grains and scruples?


Is that the European 0.3" or the African 0.3"?

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## Milosh (Apr 4, 2019)

yulzari said:


> The one I can never get my head around is 'next Friday'. Is that the next Friday you come across so, on a Wednesday, it would be this week's Friday or is it the Friday next week which is the 2nd Friday you get to? Don't get me started on 'Friday week'. I always have to confirm with the date. Have we digressed?


 Next Friday would be the Friday after this Friday.


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## Shortround6 (Apr 4, 2019)

_Is that the European 0.3" or the African 0.3"? _

laden or unladen?

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## pbehn (Apr 4, 2019)

yulzari said:


> The one I can never get my head around is 'next Friday'. Is that the next Friday you come across so, on a Wednesday, it would be this week's Friday or is it the Friday next week which is the 2nd Friday you get to? Don't get me started on 'Friday week'. I always have to confirm with the date. Have we digressed?


 It depends where you are (like all these things) In UK the coming Friday is "This Friday" and the following one is "next Friday". They all make perfect sense until you meet people with a different convention, as with units of various measures they all made sense until people started trading across the world and science started linking them all together. To understand it you need to understand cricket. The imperial system was killed in UK by adding machines and calculators which couldn't cope with or present financial transactions, my brother used to sell them in the sixties.


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## BiffF15 (Apr 4, 2019)

Shortround6 said:


> _Is that the European 0.3" or the African 0.3"? _
> 
> laden or unladen?



EXACTLY what popped to mind when I read that!



Start at 2:50...

Funny scene.

Cheers,
Biff

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## BiffF15 (Apr 4, 2019)

Peter Gunn said:


> I can neither confirm nor deny that any of this so called "button pushing" has ever taken place on my watch. And as far as my car keys, I'm sending both *you* and *pbehn* a bill for replacement keys and fobs. Since I can't get into my vehicle I've been stuck here at the Blue Parrot Bar and Grille for the last couple of days. Although I must say, the floor show is simply fabulous...



Don’t forget to send your bar tab as well!

Cheers,
Biff


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## XBe02Drvr (Apr 4, 2019)

Peter Gunn said:


> I can neither confirm nor deny that any of this so called "button pushing" has ever taken place on my watch. And as far as my car keys, I'm sending both *you* and *pbehn* a bill for replacement keys and fobs. Since I can't get into my vehicle I've been stuck here at the Blue Parrot Bar and Grille for the last couple of days. Although I must say, the floor show is simply fabulous...


Hate to tell you this, but you shoulda looked at the pavement markings when you parked the other night. You were in a "RESERVED" spot the Admiral uses when he hangs out incognito at the Parrot, and your "vehicle" (heap? wreck? jalopy?) now resides in the base impoundment compound. It can be redeemed for the price of a $500 fine and tow charge, an updated registration, and an inspection sticker. And you were so absorbed with the pulchritude you didn't even notice it was gone.
Cheers,
Wes

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## DerAdlerIstGelandet (Apr 4, 2019)

Did someone take their toys and go home?


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## KiwiBiggles (Apr 4, 2019)

DerAdlerIstGelandet said:


> Did someone take their toys and go home?


That's a bit harsh on the P-39. I'd never call it a grown-up fighter, but it wasn't altogether useless.

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## Peter Gunn (Apr 5, 2019)

BiffF15 said:


> Don’t forget to send your bar tab as well!
> 
> Cheers,
> Biff


I will but it's quite extensive, there were many, shall we say, "House Specialties" charged up, I'm not sure said parties are well heeled enough to have the coin available to cover it.

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## BiffF15 (Apr 5, 2019)

Peter Gunn said:


> I will but it's quite extensive, there were many, shall we say, "House Specialties" charged up, I'm not sure said parties are well heeled enough to have the coin available to cover it.



As long as you kept the little umbrellas you’re covered!

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## Greg Boeser (Apr 5, 2019)

...and the tassels.

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## Peter Gunn (Apr 10, 2019)

I just realized, I believe this plane must have been out performed by the P-39...

Was there last Saturday for Sun 'n Fun, this was awesome, I did not film this but it's still cool***

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## P-39 Expert (Apr 10, 2019)

Peter Gunn said:


> I just realized, I believe this plane must have been out performed by the P-39...
> 
> Was there last Saturday for Sun 'n Fun, this was awesome, I did not film this but it's still cool



Maybe, but certainly outperformed by the Twin Airacobra.

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## pbehn (Apr 10, 2019)

P-39 Expert said:


> Maybe, but certainly outperformed by the Twin Airacobra.


Only when two fuel tanks and the armour were removed.

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## P-39 Expert (Apr 10, 2019)

pbehn said:


> Only when two fuel tanks and the armour were removed.


No fuel tanks removed, only nose armor plate removed. Do I have to go over all this again?

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## Peter Gunn (Apr 10, 2019)

***No Fuel tanks or armor were harmed in the making of this video...

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## drgondog (Apr 10, 2019)

pbehn said:


> Only when two fuel tanks and the armour were removed.



AND the Merlins were replaced by Allisons.

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## pbehn (Apr 10, 2019)

drgondog said:


> AND the Merlins were replaced by Allisons.


I didn't know the twin airacobra had Merlins.


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## CORSNING (Apr 10, 2019)

I thoroughly despise what Mr. Bell did to the United Kingdom in 1939/40/41.
That was then. During 1943 the Russians, our allies needed something much
greater than the P-400/P-39D-1 they were given as hand-me-downs earlier
in the war. They received such in the P-39N and later P-39Qs. Most of the
discussion so far has been of the earlier Airacobras..
Good night all, Jeff

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## fubar57 (Apr 10, 2019)



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## buffnut453 (Apr 10, 2019)

Where's my popcorn when I need it?


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## Peter Gunn (Apr 12, 2019)

buffnut453 said:


> Where's my popcorn when I need it?


Ask and ye shall receive...

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## Peter Gunn (Apr 12, 2019)

So here's something else I ran across, Luftwaffe pilots surrendering to the USAAF, first one is a pristine looking Fw-190 long nose, as it's towed away it looks like a P-51B or C in the background with a Malcolm Hood on it. The Stuka comes in with a Mustang escort as well. Cool stuff.

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## Milosh (Apr 12, 2019)

The D-9 has Stab markings, so anyone know who the pilot is?

The Ju87 has flame damper exhaust.

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## P-39 Expert (Apr 12, 2019)

Milosh said:


> The D-9 has Stab markings, so anyone know who the pilot is?
> 
> The Ju87 has flame damper exhaust.


The Stuka had flame dampener exhaust? A night dive bomber? Sounds dangerous.


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## fubar57 (Apr 12, 2019)

They were starting to be used at night with the D-3N variant, flame dampener exhaust included

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## pbehn (Apr 12, 2019)

The late model P-39 Y version had all armament and fuel in a pod under the fuselage and armour fixed with Dzus fasteners, they were of course useless but popular with ground crew.

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## P-39 Expert (Apr 13, 2019)

fubar57 said:


> They were starting to be used at night with the D-3N variant, flame dampener exhaust included


As dive bombers???


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## Milosh (Apr 13, 2019)

Naturally.


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## XBe02Drvr (Apr 13, 2019)

pbehn said:


> The late model P-39 Y version had all armament and fuel in a pod under the fuselage


You mean Convair didn't INVENT that idea for the B58 as they claimed? You've shattered my faith in the innovativeness of General Dynamics! Fie on them!

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## pbehn (Apr 13, 2019)

XBe02Drvr said:


> You mean Convair didn't INVENT that idea for the B58 as they claimed? You've shattered my faith in the innovativeness of General Dynamics! Fie one them!


You will find most post war designs trace back to the P-39, even the B58 if you look at it in a very very very low light.

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## XBe02Drvr (Apr 13, 2019)

pbehn said:


> You will find most post war designs trace back to the P-39, even the B58 if you look at it in a very very very low light...


...and you've just staggered back from the pub.

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## fubar57 (Apr 13, 2019)

P-39 Expert said:


> As dive bombers???


Not so much dive bombing........."Confronted with a hostile air environment, by mid-1943 the Stuka was limited mostly to night operations. The Ju-87 D-5 had no particular optimizations for flying at night, with pilots coming in low and slow and dropping antipersonnel bombs on groups of incautious Allied troops. The Luftwaffe learned this trick from the Soviets, who had become fond of using little Po-2 biplanes on such harassment raids earlier in the war."

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## P-39 Expert (Apr 13, 2019)

fubar57 said:


> Not so much dive bombing........."Confronted with a hostile air environment, by mid-1943 the Stuka was limited mostly to night operations. The Ju-87 D-5 had no particular optimizations for flying at night, with pilots coming in low and slow and dropping antipersonnel bombs on groups of incautious Allied troops. The Luftwaffe learned this trick from the Soviets, who had become fond of using little Po-2 biplanes on such harassment raids earlier in the war."


You, sir, have way too much time on your hands.


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## fubar57 (Apr 13, 2019)

7 day weekends help

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## CORSNING (Apr 13, 2019)

November 1942 the P-39N deliveries begin to the USAAF. April 1943 the P-39N is supplied
to the French in North Africa. June 1943 the 18th FG becomes operational at Guadalcanal in
their P-39Ns.

It looks like the comparison is with the Fw 190A-4/-5/-6 and Bf 109 G-2 thru G-6 (early variants).


objections?

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## CORSNING (Apr 14, 2019)

No misconceptions, the P-39s did not have the range of the Allison powered Mustangs.
It did not have the high altitude performances of the Merlin powered Mustangs. No version
of the P-39, or P-63 for that matter, was particularly suited for the European Theater of Operation.
I do not believe that even the P-39N/Q should be considered as in the same class as the Bf 109G
and later Fw 190As, at least not at altitudes above 6,000m.
My purpose with this posting is to attempt to show why the Russians who's air war was mainly
below 5,500m., were able to hold their own against the best of the Luftwaffe with Bell's second
hand little fighter.





I saw you George

The P-39N information comes from aircraft 42-4400 testing in report dated 24 Nov. 1942.
The Bf 109G-2 information comes from the Russian tests. The Finnish tests produced
better climb rates but much lower speeds and I do not have a weight listing for the Finnish
Bf 109G-2. The FW 190A-5 information comes from the Augsburg test 19 June 1943.

Altitude / Speed
Meters / MPH: Bf 109G-2 / FW 190A-5 / P-39N
S.L........326 /* 352 */ 344
1,000...344 /* 368 */ 362
2,000...362 / 370 / *381*
3,000...374 / 367 /* 398*
4,000...378 / 378 / *394*
5,000...379 / 397 /* 388*
6,000...398 / *415* / 382
7,000...414 /* 417 /* 376
8,000*...410 */ 407 / 367

FTH: 414 @ 7,000 / 422.5 @ 6,375 / 398.5 @ 2,957

Altitude / Climb
Meters / FPM: Bf 109G-2 / FW 190A-5 / P-39N
S.L........3740 / 3265 / *3980*
1,000...3975 / 3345 / *4145*
2,000...4134 / 2855 /* 4220*
3,000...3720 / 2500 / *3940*
4,000...3445 / 2480 / *3460*
5,000...*3208* / 2460 / 3060
6,000...*3130 */ 2155 / 2685
7,000...*2598 / *1692 / 2230
8,000...*2086 */ 1250 / 1745

Time to 3,000m: 2.6 / 3.1 /* 2.38 *minutes.

Combat Ceiling (1,000 fpm): *10,080 */ 8,595 / 9,700 meters.

Power Loading (lbs./hp.): *4.581 */ 4,911 / 5..122

Wing Loading (lbs./sq. ft.): 38.46 / 42.54 / *34.15*

Armament: Bf 109G-2: 1 x 20mm/150 rd.+ 2 x 7.9mm/500 rpg
FW 190A-5: 2 x 20mm/250 rpg + 2 x 20mm/60 rpg + 2 x 7.9mm/850 rpg
P-39N: 1 x 37mm/30 rd + 2 x 0.5cal/200 rpg + 4 x 0.3cal/300 rpg

Note: Russian P-39N and Qs mostly had 1 x 37mm/30 rds + 2 x 12.7mm/200 rpg
this improved climb and speed. The fact that their pilots push the engine just
slightly helped a bit also.

Internal fuel range: 340 mls / *497 mls */ 360 mls w-87 gal. and *525 mls *w-120 gallons.

As I said, the Airacobra was a slightly cheaper cut. But it was not the complete
lemon that a lot of authors and WW2 aircraft enthusiast believe it to be.

, Jeff

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## pbehn (Apr 14, 2019)

I have booked a massage for my back, I have a feeling I am going to be loading and unloading tanks guns ammo and armour very soon.

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## GrauGeist (Apr 15, 2019)

P-39 Expert said:


> You, sir, have way too much time on your hands.


Ask a question, get an answer...typically, that's how it works.
The Ju87D (and some modified earlier variants) were used for night attack against Allied positions (both eastern and western fronts).

I'm kind of surprised that some people are unaware of this common bit of knowledge.

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## P-39 Expert (Apr 15, 2019)

CORSNING said:


> No misconceptions, the P-39s did not have the range of the Allison powered Mustangs.
> It did not have the high altitude performances of the Merlin powered Mustangs. No version
> of the P-39, or P-63 for that matter, was particularly suited for the European Theater of Operation.
> I do not believe that even the P-39N/Q should be considered as in the same class as the Bf 109G
> ...



Here's what I got. The Me109G is the base G model at 6724# with 20mm and 2x.30cal MGs synchronized and non retracting tailwheel. Any increase in weight (30mm cannon or 13mm MGs, underwing weapons) and speed/climb fall off. As you can see the P-39N is a good bit faster up to 20000'. Then the Me109G ends up about 25kph (15mph) faster at 25000'. The bumps for the 13mm MGs would reduce the speed by 6mph so now the 109G is only about 9mph faster at 25000'.

Regarding climb, the P-39N is much faster below 20000' and about the same up to 25000'. And better range/endurance than the 109G. And more maneuverable.

The FW190A6 is slower than the P-39N up to 20000' but still about the same as the A6 combat speed at 26000'. At that altitude the N is about 40kph (25mph) slower than their WEP setting good for 1 minute.

In climb the P-39N outclimbs the FW190A substantially at all altitudes. And better range/endurance than the FW190A6. And more maneuverable.

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## Peter Gunn (Apr 16, 2019)

pbehn said:


> I have booked a massage for my back, I have a feeling I am going to be loading and unloading tanks guns ammo and armour very soon.


I got you an early (or late) birthday gift, it's battery powered...

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## swampyankee (Apr 16, 2019)

pbehn said:


> I have booked a massage for my back, I have a feeling I am going to be loading and unloading tanks guns ammo and armour very soon.




Don't you have teenaged boys around? They're good for that sort of thing, and they heal faster when they drop something heavy on their feet. Of course, it's really hard for them to work as they can't get away from their phones and gameboys.

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## P-39 Expert (Apr 16, 2019)

pbehn said:


> I have booked a massage for my back, I have a feeling I am going to be loading and unloading tanks guns ammo and armour very soon.


No unloading needed for the N, it will perform just fine with wing guns or fuel. The unloading would have helped the P-39D, F, K, and L. Of course unloading the wing guns (and nose armor plate) would have helped the N also, but it already climbed well at normal gross weight.


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## Acheron (Sep 6, 2020)

I would like to use the expertise of you other forum members to ask about more obscure aircraft.

For example, what do you have to say when comparing the P-39 vs the P-40? All I (think to) know so far:

- The US used the P-40, not the P-39.
- Both had poor high-altitude performance.
- The P-39 had the engine behind the cockpit and could field a big 37-mm gun in the front.
- According to wikipedia, the P-40 had the stronger engine.
- Also according to wikipedia, the P-39 was faster than the P-40, though this could easily be due to comparing different versions or altitudes. Otherwise, I would assume the P-39 to be preferred over the P-40.

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## Vincenzo (Sep 6, 2020)

Acheron said:


> - The US used the P-40, not the P-39.
> -



USAAF statistical digest 
P-39 on hand overseas
January '42: 193
July '42: 523
January '43: 788
July '43: 1,131
January '44: 864
July '44: 541
January '45: 187
July '45: 29

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## SaparotRob (Sep 6, 2020)

There’s a great little ditty about the P-39 to be found in the book World’s Worst Aircraft. I’m sure someone here who has the book can quote it. 
BTW I don’t care if it’s true or not.


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## GregP (Sep 6, 2020)

Don't give me a P-38 with props that counter-rotate
They'll loop, roll and spin but they'll soon auger in
Don't give me a P-38!

CHORUS:
Just make me Operations
Way out on some lonely atoll
For I am too young to die
I just want to go home.*

Don't give me a P-39 with an engine that's mounted behind
It will tumble and roll and dig a big hole
Don't give me a P-39.

Don't give me an old Thunderbolt. It gave many pilots a jolt
It looks like a jug and it flies like a tug
Don't give me an old Thunderbolt!

Don't give me a Peter Four Oh, a hell of an airplane, I know
A ground loopin' bastard. You're sure to get plastered
Don't give me a Peter Four Oh.

Don't give me a P-51, it was all right for fighting the hun
But with coolant tank dry. you'll run out of sky
Don't give me a P-51.

Don't give me a P-61, for night flying is no fun
They say it's a lark. but I'm scared of the dark
Don't give me a P-61.

Lyrics from, "There I was, Flat on My Back" by Bob Stephens.

Hi Acheron,

The P-39 Airacobra and P-40 Warhawk (Tomahawk and Kittyhawk also) both had the same engine ... an Allison V-1710. The one in the P-39 was an E-series that did not have a shaft for a propeller, but rather had a shaft for remote drive. It fed a driveshaft that went under the pilot and through his legs to the remote gearbox on the nose that drove the propeller. The engine in the P-40 was an F-series and had a standard SAE 50-spline prop shaft and the propeller was mounted to it. But the power sections were identical in appearance otherwise. Both had a single-stage supercharger but no turbocharger.

Most of the P-39s had V-1710s rated at about 1,200 HP. Some had engines with 1,325 HP. It was a good performer at or below 15,000 feet, but the engine rapidly lost performance above 15,000 feet. Yes, it could get up to 35,000 feet or so, but it didn't have fighter-like performance up there.

In the lyrics above, it says, "It'll tumble and roll and dig a big hole." During WWII, some pilot stated the P-39 would tumble in mid-air. A few survived it and complained to the USAAF about it. The USAAF said it couldn't duplicate that behavior in the wind tunnel, and they couldn't. After the war, they found one of the P-39 wind tunnel models and discovered it was ballasted to simulate a full loadout of ammunition. The ammunition in the P-39 is ahead of the center of gravity, and shooting all of it moved the CG rearward. Some guys decided to test the model in the wing tunnel ballasted for empty ammunition and, surprise, it tumbled easily when stalled! Go figure.

The P-40 used a similar engine that was rated mostly at about 1,325 hp. Some had engines of 1,425 HP or so. Two variants of the P-40, the P-40F and P-40L, had Packard-Merlin V-1650 engine, but the Merlins so used were single-stage engines and the resulting P-40s performed almost the same as with the Allison engines. The Merlin-powered units were very slightly faster and had very slightly better altitude performance, but not enough to make much of a difference. They were still low-altitude fighters. You can tell the Merlin units because they airscoop on top of the nose is missing.

The U.S.A. used both aircraft, though we DID use more P-40s than P-39s. The P-39 had a sister aircraft development that looked very similar to the P-39, called the P-63 Kingcobra. It was a bigger airplane that also used the Allison engine, but the horsepower rating was also higher. The U.S.A. used very few of the P-63s. Most went to the Soviet Union, who loved them since they were employed as ground-support aircraft at low altitudes where they shined in performance. You can tell a P-39 and P-63 apart by the shape of the vertical tails. Google them both, check the shape of the tail, and you can instantly tell which one you are looking at.

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## SaparotRob (Sep 6, 2020)

GregP said:


> Don't give me a P-38 with props that counter-rotate
> They'll loop, roll and spin but they'll soon auger in
> Don't give me a P-38!
> 
> ...


I didn’t know there was more. This goes onto the “What cheered you up today?” thread!
I would have used more exclamation points but that’s been done to death.

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## FLYBOYJ (Sep 6, 2020)

One more time! _"Don't give me a P-39 with an engine that's mounted behind
It will tumble and roll and dig a big hole
Don't give me a P-39"_

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## SaparotRob (Sep 6, 2020)

Just looked up that title hoping to find a recording. 
If I didn’t look up the wrong guy, Bob Stephens was a minor league pitcher and enlisted after the attack on Pearl Harbor. He became a fighter pilot flying Mustangs and had a dozen kills. His P-51B was named “Killer” from his father’s nickname. He was killed in a two seat F-100 while checking out a new pilot.
I got this from the website baseballinwartime.com. after entering “there I was, flat on my back bob Stephens”. He has books of aviation cartoons as well. The stuff I learn from this Forum is amazing.


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## GregP (Sep 6, 2020)

Sorry, Bob Stevens, not Stephens ... my mistake.

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## Elmas (Sep 6, 2020)

Give me operations – Oscar Brand

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## SaparotRob (Sep 6, 2020)

GregP said:


> Sorry, Bob Stevens, not Stephens ... my mistake.


Not a problem. I learned a lot and perhaps someone might model Captain Stephens’ P-51B. I believe he flew with the 355th.


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## SaparotRob (Sep 6, 2020)

Elmas said:


> Give me operations – Oscar Brand


There we go!


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## Elmas (Sep 6, 2020)



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## MIflyer (Sep 6, 2020)

The USSR did not use the P-39 for ground attack. It was an air superiority fighter for the Soviet Air Force. Contrary to often repeated myth, the 37MM cannon could not crack open Geman tanks. In fact the USAAF claimed to the RAF that the P-39 could do as good a job as the Hurricane IID with 40MM cannon, the British did tests that proved that was not true. And they also found the 37MM cannon jammed every time they fired it, until they devised a fix by sawing off the ejection lever. The 37MM used in the P-39 was relatively low velocity and designed to attack the light structure of aircraft, not penetrate tank armor (refernce the book Druids' Circle). The 37MM used with the Stuka was designed as an ground based AA weapon and had higher velocity.

Interestingly enough, when the USSR developed better fighters such as the Yak-3, Yak-9, and LA-5 they did not use them to replace P-39's in service. See the Osprey book on the P-39.

One drawback for US use of the P-39 was it shorter range compared to the P-40. After the first few months the US primarily fought a war of offense and getting to where the enemy was of great importance. At Guadalcanal the P-39 was used to provide air cover for convoys and reportedly the P-39's generally arrived back at base virtually on fumes. I read of a case where a P-40 was yelling for help with a Zero on his tail and the only way some returning P-39's could be of help was that the Zero was basically in the traffic pattern. 

One article I posted here said that the P-39Q with the externally mounted .50 cal guns under the wings had flight characteristics inferior to the earlier models.

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## SaparotRob (Sep 6, 2020)

Acheron, I gave you a winner for starting this thread.


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## Acheron (Sep 7, 2020)

SaparotRob said:


> Acheron, I gave you a winner for starting this thread.


Thank you! 

One thing I recall, the Soviets reportedly claimed that the 37-cannon was great against the rugged FW-190. Having a radial engine, the FW-190 supposedly could take quite some punishment, but a 37-mm shell would ruin its day. I wonder though if 37-mm shells were considerably more destructive than 20-mm shells, anyone got any idea?



 GregP
and 
M
 MIflyer
regarding the use of the P-39 in a round attack role, please let us know whether you are talking about the P-39 being used as a ground-attacker in its primarily role or ground-attacks on targets of opportunity. Given the normally low altitudes of Eastern Front air combat, the later could be significant, no?

Regarding the 37-mms destructive power vis-vis the Ju-87's gun, the Ju-87 was tasked with cracking the T-34's, right? To my knowledge, the Panzer III's and IV's were considerably lighter armored (or at least had much mess slope), especially early in the war. Any ides if the P-39's 37-mm could have been effective against these?

Wikipedia is sadly not good when it comes to stats, engine power and speed at times lack the altitude for which the values are given. Was the P-39 indeed faster than the P-40 by a good margin?

And any idea why the US military got more P40's than P-39's? The reliability issues? The lower range? Or something else entirely.

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## GregP (Sep 7, 2020)

The Soviet Fighter Units were viewed by the Soviet high command as an extension of the ground Army. Their reason to be, in upper Soviet circles, was as support for ground operations.

The Luftwaffe tried coming in at high altitudes and the Soviets responded by ignoring the high-altitude German aircraft entirely and sending many aircraft at low altitude to attack the German ground troops. The Germans were faced with a simple decision: 1) Continue high-altitude attacks and suffer unsupportable ground casualties, or 2) Come down to low altitude and fight to save their ground troops. Without ground troops, there was no Operation Barbarosa. They chose to save their troops and the Soviet fighters got to dogfight with German fighters at low altitudes.

The P-39s were used as Soviet fighters. Yes, there was some ground attack involved, but the primary ground attack airplanes were Il-2 and Il-10 later on, with a few other Soviet attack types thrown in, such as the Pe-2 (outstanding) and Su-2 and others. The P-39s, P-40s, Spitfires, Hurricanes, P-47s, P-51s, etc. were mainly used to escort the attack planes in support of ground forces, so they primarily dealt with German fighters.

At first, Soviet equipment and pilots weren't very good. After mid-1941, it was hard for a Soviet fighter to live in a German sky over the Soviet Union, and many Germans racked up impressive scores quickly. The Soviets even had to move aircraft production more than 1,000 miles east to escape German bombing. But, by mid-1943, it was getting hard for a German pilot to live in a Soviet-controlled sky over the Soviet Union, Erich Hartmann notwithstanding (he got to the fight in Oct 1942). The La-5/7 were excellent, as were the Yak-3/9 series, and Soviet tactics caught up with the reality of situation. The German attacks in 1942 (Case Blue) and 1943 (Operation Citadel) were failures, helped by Russian weather, and resulted in the German retreat and eventual collapse.

At least, that is my current understanding from books and conversations with former VVS pilots and Russian internet contacts. I suppose it could be wrong ... but I'd need some evidence of it more than a few posts to think otherwise.

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## MIflyer (Sep 7, 2020)

Certainly the Soviet P-39's could and no doubt did hit targets of opportunity in terms of ground attack. The 37MM was effective against thin skinned vehicles and I recall reading that a USAAF P-39 pilot in the Med described it was great for attacking barges, a 37MM round doing a good job of clearing the decks. 

Now, the Soviets built a version of the Yak-9 that had a 45MM gun firing through the prop hub, for ground attack.

As Grep P says, there was no high altitude war in the East. Remember that neither the Germans nor the Soviets had high altitude heavy bombers in numbers that would represent even a decent airshow by US standards

But I recall that German ace Erich Hartmann said, "The P-39 performed like the BF-109 at low altitudes." That says a lot right there. It was not better than a 109, but it was in the ball game. On the other hand, the P-39 certainly was easier to land than the 109, especially the later "Beul" models. If the Soviets had been given all the 109's they wanted they would have been lucky to get one mission out of them with neophyte pilots.

And while Hartmann and some others racked up big scores against the Soviets, the real questions are, "Did they keep the IL-2's and Pe-2's off their ground troops? Did they successfully defend the Stukas and fighter bombers against the Yaks and P-39's?" The answer is NO.

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## michaelmaltby (Sep 7, 2020)

".... Did they successfully defend the Stukas and fighter bombers against the Yaks and P-39's?" The answer is NO."

However, I would argue, the P-39 in the hands of Soviet experten, _was as good_ as any Soviet fighter AC that faced the Germans. There were very extensive air battles over the Crimea and Kuban after which the Soviets ultimately achieved air superiority. Spitfires and P-39s were the principal Soviet fighter AC in that theater, IIRC

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## MIflyer (Sep 7, 2020)

michaelmaltby said:


> However, I would argue, the P-39 in the hands of Soviet experten, _was as good_ as any Soviet fighter AC that faced the Germans. There were very extensive air battles over the Crimea and Kuban after which the Soviets ultimately achieved air superiority. Spitfires and P-39s were the principal Soviet fighter AC in that theater, IIRC



I would agree with you. Note that when The Soviets brought in Yak-3's and 9's and LA-5N's they did not replace the P-39's but other fighters instead.

Here is a picture that says a lot about the P-40. It was taken near the Aleutian Islands. Note that there are short tailed P-40's that can only be E models that must have gotten there in 1942. One even has what looks like the Aleutian Tiger paint that Chennallt's son led. Also note there are are P-40N's, which did not start to come off the production lines until March 1944. The P-40N-5 with the first clear section behind the cockpit came out even later than March of 44. So we are looking at some E models that had to have been in that very harsh combat environment for at least 2 years.

In one of Edwards Parks's books about his WWII experience, a friend flying with a P-40 unit stopped by for a visit at his P-39 unit in New Guinea and said, "I don't know when we will get any new airplanes. These just won't wear out!" The P-40 had some significant faults and a number of serious inadequacies, but it clearly was one damned durable airplane. 

By the way, for you modelers, the AMT 1/48 P-40N is one of best kits to get. With not too much work you can build any Allison engined variant, since it has the long tail and a choice of either an original style "razorback" or clear aft fuselages. 

HAPPY LABOR DAY!

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## pinsog (Sep 7, 2020)

The P39 at Guadalcanal was mainly used as a ground attack aircraft against ships, barges and troops. The 37mm cannon was supposedly very effective against barges. The lack of range wasn’t a problem as I recall one pilot didn’t bother to raise his landing gear between taking off and strafing a Japanese supply ship or barge.

One big difference between the P39 and most other American fighters was that it was very vulnerable from behind. P40’s, P47’s, Wildcats, Hellcats, Corsairs and P38’s were well known for being tough. The P39 with its engine in the back could be downed pretty easily, vs the other fighters with the engine in the front protected by all the armor and aircraft structure to the rear.


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## FLYBOYJ (Sep 7, 2020)

P-400s were used at Guadalcanal as well


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## CORSNING (Sep 7, 2020)

*Here's my 2 cents worth:*



Acheron said:


> I would like to use the expertise of you other forum members to ask about more obscure aircraft.
> 
> For example, what do you have to say when comparing the P-39 vs the P-40? All I (think to) know so far:
> 
> ...


*The USAAF upper brass actually preferred the P-40 from what I have read.
1. It had a longer internal fuel range 750 ml. vs. 525 ml. in the N models.
2. It was more maneuverable.
3. It was more rugged and its engine was better protected.
I am sure there was more reasons, but that's the short take on the thread title.*

*Hope that helps Acheron.
, Jeff
*

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## Shortround6 (Sep 7, 2020)

Acheron said:


> Thank you!
> 
> One thing I recall, the Soviets reportedly claimed that the 37-cannon was great against the rugged FW-190. Having a radial engine, the FW-190 supposedly could take quite some punishment, but a 37-mm shell would ruin its day. I wonder though if 37-mm shells were considerably more destructive than 20-mm shells, anyone got any idea?
> 
> ...



A US 37mm shell weighed 608 grams and contained 45 grams of Tetryl. 
A 20mm Hispano shell weighed 130 grams and contained 10.2 grams of Tetryl (the were a number of similar shells). However the 37mm gun fired at 150-180 rounds per minute (book figure) vs the 20mm firing at around 600 rpm. A single 37mm shell was certainly destructive. the Problem was hitting the target with the low rate of fire gun (barges don't move very fast). 

The Russians may have been impressed because the projectiles out of the 20mm ShVAK cannon went around 91-96 grams and contained 4.7 or 6.1 grams of RDX and aluminium. 

For punching holes in armor you need velocity and the American 37mm didn't have a lot. The German 37mm used on the Stuka had about twice the potential energy with standard ammo and the Germans made AP rounds with tungsten cores. The US did not. 

30mm of armor was generally considered the minimum needed to defeat 75mm HE ammunition from field guns or howitzers, this was generally the minimum specified for a "shell proof" tank (See British A10 for example) A 37mm HE round would have only a very small chance of disabling a tank with a single hit. AP shot for the field guns changed things. As did the proliferation of 37-47mm AT guns with high velocity AP rounds. 

Hope that helps.

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## Acheron (Sep 8, 2020)

C
 CORSNING
and 
S
 Shortround6
thanks a lot, you are quite hellpful indeed 


S
 Shortround6
where did you et the weight and explosive weight values from the shells? I am puzzled by what I read on wikipedia regarding German comparative cannons:
MK108: 330g shell, 85 g RDX
MG151/20: 57g shell, 3g "of HE"
Did shells of similar or even the same diameter vary that massively?

So the P-40 had superior maneuverability and range. The P-39s gimmick, the big 37-mm cannon, was overkill against fighters and due to lower RoF worse than lighter cannons. Would you folks agree with my assessment?

And do you think the 37-mm cannon might have been of use against heavy bombers (nevermind that the axis never got around to fielding these)? So even iof so, the poor altitude performance meant the P-39 as a whole would be useless I presume?



FLYBOYJ said:


> P-400s were used at Guadalcanal as well


These were P-39s, correct?


pinsog said:


> One big difference between the P39 and most other American fighters was that it was very vulnerable from behind. P40’s, P47’s, Wildcats, Hellcats, Corsairs and P38’s were well known for being tough. The P39 with its engine in the back could be downed pretty easily, vs the other fighters with the engine in the front protected by all the armor and aircraft structure to the rear.


But, if one of these other aircraft got shot form behind, sure, the engine will be safer, but what about the pilot?


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## nuuumannn (Sep 8, 2020)

Not wishing to add weight to either side of the discussion, but from a Commonwealth perspective, the P-40 was the fighter that the Commonwealth countries went to war with. For nations that were equipped with what can only be described as second rate equipment - and in the RNZAF's case truly museum piece quality; the only single-seat fighter the country had was an unarmed Gloster Grebe (!), the P-40 was a godsend and purposefully equipped the RNZAF, RAAF and RCAF in quantity and proved itself worthy of those forces' needs. Yes, the RAAF received Capstans and Mustangs, and the RCAF received FF-1s ( ) and Hurricanes and the RNZAF Corsairs, but it was the P-40 that held the line for all these air forces during the thick of the fighting.

As an aside it's worth noting that the P-39 has its own wee place in naval aviation history as the first tricycle undercarriage aircraft to operate from a British aircraft carrier. In 1944, a P-39 (sorry, Airacobra I) was used to assess the flexible deck concept the British were toying with and a landing was made on the escort carrier HMS Pretoria Castle on 4 April 1945. It was subsequently catapulted off; a notable first.

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## Tkdog (Sep 8, 2020)

Capstan?

ah found it.
An explanation is here.


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## SaparotRob (Sep 8, 2020)

Tkdog said:


> Capstan?


Hey, it worked!


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## Tkdog (Sep 8, 2020)

Indeed it did!

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## Tkdog (Sep 8, 2020)

Obscure cigarettes aside, I wonder how much of an impact the tricycle landing gear had in regards to senior officer acceptance. It’s another thing to have to train new pilots on.


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## Stig1207 (Sep 8, 2020)

GregP said:


> The Soviet Fighter Units were viewed by the Soviet high command as an extension of the ground Army. Their reason to be, in upper Soviet circles, was as support for ground operations.
> 
> The Luftwaffe tried coming in at high altitudes and the Soviets responded by ignoring the high-altitude German aircraft entirely and sending many aircraft at low altitude to attack the German ground troops. The Germans were faced with a simple decision: 1) Continue high-altitude attacks and suffer unsupportable ground casualties, or 2) Come down to low altitude and fight to save their ground troops. Without ground troops, there was no Operation Barbarosa. They chose to save their troops and the Soviet fighters got to dogfight with German fighters at low altitudes.
> 
> ...





MIflyer said:


> Certainly the Soviet P-39's could and no doubt did hit targets of opportunity in terms of ground attack. The 37MM was effective against thin skinned vehicles and I recall reading that a USAAF P-39 pilot in the Med described it was great for attacking barges, a 37MM round doing a good job of clearing the decks.
> 
> Now, the Soviets built a version of the Yak-9 that had a 45MM gun firing through the prop hub, for ground attack.
> 
> ...



Have a look at the disparity in strength between the Luftwaffe and Soviets:

Eastern  Front Aircraft Strength and Losses 1941-45 .

It would seem a lot was being asked of the German fighter pilots, defending their ground troops, escorting bombers and ground attack aircraft over a long front line. Despite that, the Soviets were still losing 3 times as many aircraft in combat as the Germans were, after mid-43 and until the end of '44 .

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## pbehn (Sep 8, 2020)

Tkdog said:


> Obscure cigarettes aside, I wonder how much of an impact the tricycle landing gear had in regards to senior officer acceptance. It’s another thing to have to train new pilots on.


Only in the heady world of an aviation write up would a capstan become an obscure cigarette.

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## FLYBOYJ (Sep 8, 2020)

Acheron said:


> These were P-39s, correct?


They were the export version of the P-39 with a 20MM cannon in the nose and 2 30 cal in the wings. The 20mm cannon was said to be more reliable than the 37mm cannon


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## CORSNING (Sep 8, 2020)

*The USAAF upper brass actually preferred the P-40 from what I have read.
1. It had a longer internal fuel range 750 ml. vs. 525 ml. in the N models.
2. It was more maneuverable.
3. It was more rugged and its engine was better protected.
I am sure there was more reasons, but that's the short take on the thread title.*

*Added tidbits;
Roll Rates* (deg./sec.) P-39D/P-40F: 200mph: 63/85, 250 mph: 72/94.5, 300 mph: 62/94,
325 mph: 60/92. From NACA chart. The P-40 rolled faster at all speeds.
*Turn Times *(360 degrees/1,000 m): P-39N-1: 19.0 sec. vs. P-40N-1: 17.0 sec. 
*Dive:* The P-40 could pull away from a P-39 in a dive fairly quickly (opinion formed from
all that I have read about both. The P-40N was a much lightened P-40 and dived a little
faster than the P-39N.
*Acceleration:* I believe it was in the book 'Forked-Tailed Devil' that I read that of the 
Allison powered aircraft the P-38 was the drag king. The p-39 & P-51 were about even
and the P-40 brought up the rear. ( I was surprised when I read that the P-40E could 
out accelerate a Spitfire V at low altitudes on the P-40E vs Spitfire V thread.)

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## Shortround6 (Sep 8, 2020)

CORSNING said:


> The P-40N was a much lightened P-40


Only the first couple of hundred (200?) P-40Ns were much lightened, later P-40Ns gained a lot of the weight back.
A number of the "light" P-40Ns gained weight back in the field as squadrons/local maintenance units added electric starters/bigger batteries, forward fuel tank, brought the number of guns back up to six and a few other changes. The Aluminium radiators/oil coolers and magnesium wheels stayed standard for the rest of production run and did shave some weight.

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## Shortround6 (Sep 8, 2020)

Acheron said:


> where did you et the weight and explosive weight values from the shells? I am puzzled by what I read on wikipedia regarding German comparative cannons:
> MK108: 330g shell, 85 g RDX
> MG151/20: 57g shell, 3g "of HE"
> Did shells of similar or even the same diameter vary that massively?



The numbers are from "Flying Guns World War II" by Anthony G. Williams & Dr Emmanuel Gustin. Guns of different calibers varied considerably as the weight _varied with *cube* of the diameter for projectiles of the same shape. _
However the shape was often not the same, the Japanese army 20mm Ho-5 cannon used a short, stumpy projectile of 79 grams, it was the lightest 20mm projectile used in an aircraft cannon. The heaviest explosive 20mm projectile used in service was 136 grams. 
Construction could also cause considerable variation. As an example the British changed to a fuse made of aluminum instead of brass post war for their 20mm cannon before the ADEN cannon. No other change and the weight dropped from 128-130 grams to 116 grams. Quality of the steel used governed how thick the shell walls needed to be as did the intended velocity of the shell, higher velocity shells need stronger walls to keep them from buckling when fired. 
The Germans developed a new way of making shells, drawing the steel into a tube much like a cartridge case is drawn from a slug or short cup into a full length case. However the thin walls, while allowing higher explosive content, didn't provide much material for fragments. These were the famous mine shells like the MK 108 330 gram shell. The older shell used in the MK 101 (and MK 103) cannon weighed 433 grams and held 29 grams of explosive. 
I would note that putting a tracer component in a shell often cut the HE content considerably so make sure you are comparing like to like. 



Acheron said:


> So even iof so, the poor altitude performance meant the P-39 as a whole would be useless I presume?



Maybe, most of the axis bombers didn't have very good altitude performance. The Japanese managed to attack with bombers well into the 20,000ft range but they weren't all that fast at high altitudes and their small bomb loads were also a handicap.

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## GregP (Sep 8, 2020)

Hi Archeron,

You might try to Google "The Great Fighter Gun Debate" for gun tables. It goes a long way toward explaining the columns and numbers.


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## nuuumannn (Sep 8, 2020)

Tkdog said:


> Capstan?



The worst kept secret in Australia. Capstan was adopted as the code name for Spitfires being sent to defend the country.



Tkdog said:


> I wonder how much of an impact the tricycle landing gear had in regards to senior officer acceptance. It’s another thing to have to train new pilots on.



The RAF employed civilian tricycle undercarriage aircraft to train crews transitioning onto US types that entered the RAF, such as the Boston, Mitchell Liberator and Marauder. Specifically this one, the GAL Cygnet, which not only bears the distinction of being the first tricycle undercarriage aircraft built in Britain, but the first all-metal stressed skin monoplane lightplane built in Britain.




Cygnet

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## MakerDude (Sep 10, 2020)

I have read a lot of the P-39 lend-lease.net articles and noticed that the soviets tended to use the p-39 slightly differntly than the west. Whereas most pilots in the west would shoot at 200+ yards, the Soviets would shoot at about 80 yards.


Shortround6 said:


> A US 37mm shell weighed 608 grams and contained 45 grams of Tetryl.
> A 20mm Hispano shell weighed 130 grams and contained 10.2 grams of Tetryl (the were a number of similar shells). However the 37mm gun fired at 150-180 rounds per minute (book figure) vs the 20mm firing at around 600 rpm. A single 37mm shell was certainly destructive. the Problem was hitting the target with the low rate of fire gun (barges don't move very fast).
> 
> The Russians may have been impressed because the projectiles out of the 20mm ShVAK cannon went around 91-96 grams and contained 4.7 or 6.1 grams of RDX and aluminium.
> ...


One of the reasons the Soviets were able to get more out of it was instead of firing at 200+ yards like the British and Americans they fired at about 80 yards. Alexander Pokryshkin there No 2 ace said it was easy to destroy your opponent, get to withing 80 yards pull the trigger and watch your opponent disintegrate. At that close range the low velocity of the 37mm and its low rate of fire become less important. The Soviets matched their tactics to their equipment.

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## jmcalli2 (Sep 10, 2020)

Acheron said:


> I would like to use the expertise of you other forum members to ask about more obscure aircraft.
> 
> For example, what do you have to say when comparing the P-39 vs the P-40? All I (think to) know so far:
> 
> ...



- The US used BOTH the P-40 and the P-39.
- Both the P-40 and the P-39 used the Allison V-1710 except for a few P-40s that used the mid-altitude version of the Merlin V-1650.
- The P-39 was faster than the P-40.
- The aircraft were designed for different missions; the P-40 was a general purpose fighter while the P-39 was designed to an interceptor specification ( Both the P-38 and P-39 were designed to the same specification. The P-38 went with two engines to achieve the required performance while the P-39 tried to be the smallest single engine fighter possible to get there. The big cannon was part of the requirement. By the time the P-39 flew, the Army decided there was little threat from high level bombers and pulled the turbo from the P-39 to save weight. This limited the P-39's effectiveness to below ~18,000 ft, the same level as the P-40. )

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## Shortround6 (Sep 10, 2020)

jmcalli2 said:


> The P-38 went with two engines to achieve the required performance while the P-39 tried to be the smallest single engine fighter possible to get there.



Most of the requirement/s were the same. However the requirement that led to the P-38 wanted_ one hour more endurance _at the same speed/altitude (actually double from one hour to two hours) than the requirement that led to the P-39. It was the weight/bulk of the extra fuel that that made the P-38 so much larger. The specification might have been meet by single engine aircraft had a 1500hp single engine been available at the start of design. Such an engine was not available requiring the use of two 1000hp engines which made the proposed plane even larger. 
What led to the P-39 was never intended to have the endurance of the requirement that led to the P-38. 




jmcalli2 said:


> By the time the P-39 flew, the Army decided there was little threat from high level bombers and pulled the turbo from the P-39 to save weight. This limited the P-39's effectiveness to below ~18,000 ft, the same level as the P-40. )



No, the turbo installation in the P-39 was a dog's breakfast (as was the original oil cooler and radiator) , and the turbo (and controller/s) were not ready for squadron use. The original XP-39 was never going to come near the projected/estimated performance numbers. The only way to get even close was to ditch the turbo, ditch the intercooler and totally redesign the oil cooler/radiator installation (putting them were the turbo had been).

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## P-39 Expert (Sep 10, 2020)

We should always compare contemporary P-39s and P-40s. Those that were in production about the same time. P-39D/F and P-40E had the same 1150hp engines. P-39K/L and P-40L had the same 1325hp engines. The P-39M/N/Q and the P-40M/N had the 1200hp engines with the higher 9.6 supercharger gears for better altitude performance.

In every contemporary situation the P-39 was substantially lighter (7650#) vs the P-40 (8400#). That's about 750# difference. With both having the same engine the P-39 performance is always going to be better. Faster and particularly better in climb/ceiling. All the tests in Mike William's site confirm this, just impossible for it to be any other way. Maneuverability was supposedly very close, some give the edge to the P-40.

The Merlin P-40 was a substantial improvement and brought performance up to about exactly the same as a contemporary P-39D/F/K/L. Merlin had more power at the higher altitudes. Performance was not nearly as good as the P-39N. Performance in the Q was degraded by the gondola .50cal machine guns under the wings.

Range/endurance was about the same for both. The P-40 held more internal fuel but had a much higher allowance for take off and climb to 5000' than the P-39 making usable fuel closer to equal. The P-39's higher cruising speed at equal power settings made up for the rest.

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## varsity07840 (Sep 10, 2020)

The P-39k/L had an Allison. The P-40L had a Merlin.


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## P-39 Expert (Sep 10, 2020)

varsity07840 said:


> The P-39k/L had an Allison. The P-40L had a Merlin.





varsity07840 said:


> The P-39k/L had an Allison. The P-40L had a Merlin.


Right. I was thinking K and I hit L. My bad.

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## FLYBOYJ (Sep 10, 2020)

Acheron said:


> - The US used the P-40, not the P-39.


You're joking, right?

_From Joe Baugher:_

The following Fighter Groups operated the P-39 between 1941 and 1945, but in some cases only relatively briefly:

8th Fighter Group (35th 36th and 80th Squadrons
15th Fighter Group (12th 15th and 36th Squadrons)
18th Fighter Group (78th and 333rd Squadrons)
20th Fighter Group (55th, 77th, and 79th Squadrons)
21st Fighter Group (531st Squadron)
31st Fighter Group (39th, 40th, and 41st Squadrons)
33rd Fighter Group (58th, 59th, and 60th Squadrons)
52nd Fighter Group (2nd and 4th Squadrons)
53rd Fighter Group (13th, 14th, and 15th Squadrons)
54th Fighter Group (42nd, 56th, and 57th Squadrons)
56th Fighter Group (61st, 62nd, and 63rd Squadrons)
58th Fighter Group (67th, 68th, and 69th Squadrons)
318th Fighter Group (72nd Squadron)
332nd Fighter Group (99th, 100th, 301st, and 302nd Squadrons)
338th Fighter Group (305th, 306th, and 312th Squadrons)
343rd Fighter Group (18th Squadron)
347th Fighter Group (67th, 68th, and 70th Squadrons)
350th Fighter Group (345th, 346th, and 347th Squadrons)
354th Fighter Group (353rd, 355th, and 356th Squadrons)
357th Fighter Group (362nd, 363rd, and 364th Squadrons)
367th Fighter Group (392nd, 393rd, and 394th Squadrons)
372nd Fighter Group (407th, 408th, and 409th Squadrons)
473rd Fighter Group (451st and 452nd Squadrons)
P-39s were also used by the 342nd Composite Group (33rd Squadron) and the 59th Observation Group (488th, 489th and 490th Squadrons). The P-39 was also used by the 48th, 84th, 85th, 339th, 494th, 405th, 496th, and 478th Bombardment Groups in the training role.

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## Greg Boeser (Sep 11, 2020)

You forgot 35th Pursuit/Fighter Group, (39th, 40th, 41st Squadrons)

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## glennasher (Sep 11, 2020)

P-38s, P-39s, and P-40s were all used extensively in the Alaska campaigns, to move the Japanese off Attu and Kiska. While the Aleutians campaign wasn't a major operation, in the scheme of things, it was pretty important, nonetheless. They were used for armed recon, and for defense at the air bases scattered over the island chain, and to keep the Japanese at bay. The P-39s were highly valued up there.

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## MIflyer (Sep 11, 2020)

jmcalli2 said:


> By the time the P-39 flew, the Army decided there was little threat from high level bombers and pulled the turbo from the P-39 to save weight.



A common misconception, often repeated. I have even seen clueless but successful writers say something like, "In isolationist America the Army wanted to focus on ground attack aircraft to defend the beaches in case of an invasion." POPPYCOCK!

In reality the USAAF was totally focused on the turbo as a first stage supercharger for a a two stage system. They even tried the turbo on the P-36/40 airframe, to produce the XP-37 - and it worked, adding 50 mph speed at higher altitudes, as long as you did not want the pilot to be able to see anything from that cockpit way back in the tail.

Actually, stuffing that turbo in such a small airframe resulted in MORE drag and LOWER performance than the same airplane without the turbo. The high speeds quoted for the XP-39 were WITHOUT the turbo.

Now, as to why Allison did not produce a V-1710 with a two speed supercharger, which would have been incredibly easy for them, given the V-1710's removable accessory section, is something I have wondered about. Just about every other aircraft engine company in the word did do that.

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## Shortround6 (Sep 11, 2020)

MIflyer said:


> Actually, stuffing that turbo in such a small airframe resulted in MORE drag and LOWER performance than the same airplane without the turbo. The high speeds quoted for the XP-39 were WITHOUT the turbo.



Actually the high speeds quoted for the XP-39 before the turbo was removed may have been the result of an over achieving sales dept

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## GregP (Sep 11, 2020)

Hi Miflyer,

I worked in an Allison shop for several years. The owner has copies of several requests from Allison to the USAAF to develop an integral 2-stage unit, but none were approved for funding. Despite being bought by GM, Allison was essentially a small company, and did not have the funds or manpower to develop such a 2-stage supercharger system without backing from their largest customer.

When the 2-stage unit was not funded, they concentrated on delivering the contracts they had. The late-blooming auxiliary stage supercharger was a low-cost, company-funded effort to compete (basically a new case around the existing internal design of a supercharger plus a coupling shaft), but the Air Corps SHOULD have funded at least a trial engine or two using the 2-stage Merlin supercharger unit and an adapter. At least they could have seen what they were passing up.

Alas, it was not to be. If you needed to fight at 25,000 - 35,000 feet, you were forced to use a 2-stage Merlin / Griffon or 2-stage radial ... 2-stage in any case. Fairly poor planning in my opinion, but it happened that way as we all know. Allison never DID make the integral 2-stage supercharger we all wished they had made.

A separate thread might be very interesting on the development of a high-altitude version of the R-2800. In addition to supercharger issues, they had a major ignition problem. They even tried a pressurized ignition harness! It worked, but was never going to be reliable in the field, so they came up with low-voltage ignition and moved the coils out to the spark plugs to reduce voltage loss in the plug wires. But, that's another story.

Cheers.


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## P-39 Expert (Sep 11, 2020)

MIflyer said:


> A common misconception, often repeated. I have even seen clueless but successful writers say something like, "In isolationist America the Army wanted to focus on ground attack aircraft to defend the beaches in case of an invasion." POPPYCOCK!
> 
> In reality the USAAF was totally focused on the turbo as a first stage supercharger for a a two stage system. They even tried the turbo on the P-36/40 airframe, to produce the XP-37 - and it worked, adding 50 mph speed at higher altitudes, as long as you did not want the pilot to be able to see anything from that cockpit way back in the tail.
> 
> ...


Turbo in the P-39 was totally unworkable, smart move to delete it to get the P-39 (and P-40) in production in time for U.S. entry into WWII.

AAF was focused on the turbo for the P-38 and P-47 which delayed their introduction into combat until Dec '42 and May '43 respectively. 1942 was fought almost solely by the P-39, P-40 and F4F for the USN. All three of these planes were grossly overweight as compared to British and Axis fighters. All three could have been lightened in the field to substantially improve their performance particularly in climb and ceiling.

Regarding the two SPEED supercharger, it was not really needed in the P-39 and P-40. Their single speed was high gear, a second speed would have been a low gear which would have provided a small increase in takeoff power at the expense of more weight and complexity. Takeoff power was already being increased from 1150HP to 1325HP with the -63 and -73 models of the Allison in mid '42. These were installed in the P-39D-2/K/L and the P-40K. Time limit for military power was also increased from 5 minutes to 15 minutes at that time.

The real payoff for high altitude performance was the two STAGE Allison-47 which was tested in the experimental P-39E in April '42. Unfortunately the P-39E was extensively redesigned with six .50cal machine guns AND the 37mm cannon and weight increased from 7650# to 8900#. High speed was improved to 386mph at 21,500' and ceiling increased to 35,000' but the single stage P-39N then in development was about that fast and climbed significantly better. So the P-39E was not produced. 

A much easier and quicker fix would have been to just install the two stage -47 in a standard P-39D/F. The auxiliary first stage added 175# and the required 4 blade propeller another 75# for a total added weight of 250#. Add this to the normal P-39D at 7650# and the two stage P-39 would have weighed only 7900# as compared to the P-39E at 8900#. The extra 400HP at high altitude coupled with the 1000# weight savings would have made this plane a rocket. Performance would have been better than the P-38 and P-47. All this in mid'42. Oh well, hindsight is always 20/20.


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## MIflyer (Sep 11, 2020)

I think you'd better forget about building any two stage supercharged engine without an Intercooler/Aftercooler. They tried no intercooler in the F-82 and had endless problems; the airframes set for years at the old Vultee plant in Downey with no engines because they could not get the V-1710's to run right.

And I guess I took too much thermodynamics in college and have had too much experience running tests with aircraft air to air HEX in test cells, but I find it incredible that no one but Stanley Hooker came up with the idea for an air to liquid aftercooler, thereby solving the space, drag, AND the control problem in one swell foop. Just for that they should not only knighted him but made him king of New Zealand or something. Actually the Merlin 61 was BOTH intercooled and aftercooled since the fluid picked up some heat between the stages as well as after them. Think what that approach could have done for drag reduction in the P-38, P-47, P-61, and B-29. But NO! Everyone could only think of air to air HEX for airplanes. The fact that Hooker, a theoretical aerodynamics expert could step outside his area of expertise shows just how brilliant he was.


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## Shortround6 (Sep 11, 2020)

P-39 Expert said:


> AAF was focused on the turbo for the P-38 and P-47 which delayed their introduction into combat until Dec '42 and May '43 respectively



The P-38 was in combat or in combat areas in Aug of 1942. 
July 31st the 27th squadron stays in Iceland as a defensive unit, relieved by the 50th Squadron Aug 26th and continues on to England. 
Aug 9th two P-38s claim to Japanese flying boats in the Aleutian Islands.
Aug 22 the 67th squadron with a mix of P-38s and P-39s arrives at Henderson Field.
Aug 31st 164 P-38s have crossed the Atlantic by air. 
P-38 recon planes were already in Australia. 



P-39 Expert said:


> All three could have been lightened in the field to substantially improve their performance particularly in climb and ceiling.



How???
remove armor?
Not fill fuel tanks?
Take out guns & ammo?
remove electric starters and fit smaller batteries? 

a reason they were heavier than British and Axis fighters was that they carried more fuel and a heavier weight of guns and ammo. This heavier payload required a heavier structure which unit mechanics would have difficulty modifying.


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## Acheron (Sep 11, 2020)

Two-stage superchargers were the ones needed to get high-performance at all altitudes, right? Sorry for my ignorance, but I was puzzled about some aircraft being better at high-altitudes than lower ones. At first I thought it was meant being relatively better higher up, but from what I read on wikipedia, it seems that certian supercharging schemes resulted in aircraft that were better higher-up in absolute terms, correct?


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## pinsog (Sep 11, 2020)

Acheron said:


> Two-stage superchargers were the ones needed to get high-performance at all altitudes, right? Sorry for my ignorance, but I was puzzled about some aircraft being better at high-altitudes than lower ones. At first I thought it was meant being relatively better higher up, but from what I read on wikipedia, it seems that certian supercharging schemes resulted in aircraft that were better higher-up in absolute terms, correct?


Correct. Take an F4F Wildcat. 2 speed engines give about 1,000 hp at about 14,000 feet. The 2 STAGE engine gives about 1,000 hp at 19,000 feet. The result is that at 19,000 feet the 2 STAGE equipped plane is faster and climbs better giving it a significant advantage

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## GregP (Sep 11, 2020)

Hi Archeron,

"Better" is relative. If you can maintain sea level horsepower as you go up, the airplane goes faster because there is less air density to produce drag.

But, a WWII fighter than can pull 6 - 8 gs down at 10,000 feet, even if only momentarily, can usually only make shallow turns at 25,000 feet + without stalling and losing significant altitude in recovery. The P-47 was one of the best way up high and was relatively not as good below 20,000 feet with regard to the performance difference with German fighters. That is, the German fighters were all pretty good in the 10,000 feet to 20,000 feet range and the P-47 was just coming into its best performance range when it got to 20,000 feet. It only got better versus the competition as the fight went up, at least until near the service ceiling. 

The P-47 was not especially fast at low altitudes, but could maintain horsepower until way up high, so it gained in relative performance versus the opposition and was likely the best-performing fighter in mass production above 25,000 feet. I more or less discount the Ta-152 solely because they only delivered about 47 of them during the entire war and only two were still operating when the war ended (two Ta-152Cs, not the high-altitude H models). There were thousands of high-altitude P-47s from the P-47D-25-RE and onward in the series operating when the war ended. Of course, the U.S.A. wasn't being bombed on a daily basis so as to hinder production ... and that definitely made a huge difference continuity of the aircraft supply chain. If we needed, say, 25 new fighters, we could get them in a short time. Not so for the Luftwaffe from late 1944 onward. When the war ended there were a lot of essentially brand new fighters sitting about with no propellers and no fuel. There wasn't anywhere nearly as much of a fuel or propeller shortage as there was the problem of delivering the fuel and props to airfields and factories while being strafed by Allied fighters late in the war.

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## Capt. Vick (Sep 11, 2020)

I remember watching one of those Dogfight programs about Guadalcanal on the history channel, where they use CGI to depict the battles. Well, they were interviewing a Wildcat pilot who said he went out with some Aircobras and since they stayed down low he felt they were the bare for him and his squadron mates.


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## MIflyer (Sep 11, 2020)

It's ironic that the USAAC/F focused on high altitude turbosupercharged aircraft ever since the advantages were demonstrated by the famous Pikes' Peak Test in WWI, where legend has it GE employed a team of horses to pull a Liberty engine up to the top where the turbo demonstrated the ability to boost the output from the normal 230 hp at 14,000 ft up to 356 hp. That sealed the deal! If you had turbos you could climb higher and outperform everyone else. And this dream was realized when the Y1B-17 demonstrated the same top speed as the USN's F2A -at 10,000 ft higher.

The USN took note of this in a big way, realizing that the threat first demonstrated by Billy Mitchell had materialized - at least on paper in Wash DC. They had already built their first carriers and now needed something to compete with the B-17. The answer was a two stage mechanically supercharged engine in Grumman's reworked F4F.

The irony was that stuffing a turbo into a single seat fighter was not easy. It required two engines like the P-38 or a large two seat airplane like the P-47 was based on. So when the war started the USN, with its lower tech approach, which the USAAC had given up on with the XP-41, that was ready to fight at higher altitudes.


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## Acheron (Sep 11, 2020)

As always, thank you all. What I read at wikipedia was, that single-stage supercharger could hurt an aircrafts performance at low altitudes. IIRC, it was because the compressed air would become hotter, not a problem high-up where it is cold, lower down though, it apparently caused issues (pre-ignition?). Guess the superchargers could not simply be turned off, at least not initially.


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## Greg Boeser (Sep 11, 2020)

Shortround6 said:


> The P-38 was in combat or in combat areas in Aug of 1942.
> July 31st the 27th squadron stays in Iceland as a defensive unit, relieved by the 50th Squadron Aug 26th and continues on to England.
> Aug 9th two P-38s claim to Japanese flying boats in the Aleutian Islands.
> Aug 22 the 67th squadron with a mix of P-38s and P-39s arrives at Henderson Field.
> ...


 54th Fighter Squadron received its first P-38Es in February 1942. It deployed to Alaska in late May. Flew the first operational mission on 3 June, a local patrol over Cook Inlet near Anchorage.

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## MIflyer (Sep 11, 2020)

A supercharger could "hurt" an aircraft's low altitude performance if it was set to a high gearing ratio so that pressure produced by the supercharger got to the maximum manifold pressure allowed before the throttle was advanced very far. It would be rather like trying to drive a manual transmission car fast in 1st gear; you would hit the redline RPM before you reached a high speed. Similarly, you would hit the redline on the manifold pressure before you had advanced the throttle very far.

Single stage superchargers in WWII did not have a means of cooling the air coming out of the supercharger, such as with an air-to-air heat exchanger. Light aircraft today usually use turbos for supercharging and sometime employ what they call an "intercooler" but which actually is an "aftercooler."

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## Shortround6 (Sep 11, 2020)

MIflyer said:


> So when the war started the USN, with its lower tech approach, which the USAAC had given up on with the XP-41, that was ready to fight at higher altitudes.



A difference was the two stage supercharger in the F4F was good for 1000hp at 19,000ft. The same P & W R-1830 when given a turbocharger (and using the same engine driven supercharger) was good for 1200hp at 25,000ft in the last versions of the P-43. It did require a bit more weight and bulk and the turbo (and controller) wasn't really ready for front line use. 


Acheron said:


> that single-stage supercharger could hurt an aircrafts performance at low altitudes. IIRC, it was because the compressed air would become hotter, not a problem high-up where it is cold, lower down though, it apparently caused issues (pre-ignition?



The problem with single stage single speed superchargers is that they can only be optimised for one altitude. The Best engine I know of for illustrating this is the Merlin. The Merlin III used in the Hurricane I Spitfire I and a several other British aircraft would hold 6lbs of boost (around 42in ) to 16,250 ft with the engine turning 3000rpm which spun the impeller at 25,764rpm. 
Please note that anytime the engine was doing 3000 rpm the impeller was spinning at 25,764rpm regardless of altitude. The air at 16,000ft is at 16.21 inches of Hg so the Merlin supercharger was compressing almost 2.6 times. If the throttle had been opened all the way at sea level the supercharger might have been able to produce 77in of manifold pressure which would have certainly either caused massive detonation with the fuel available or destroyed the engine even without detonation. By restricting the amount (volume of air) coming into the supercharger at sea level the engine made 880hp for take off at the same 3000 rpm and same 6lbs of boost (some books give 6 1/4lbs).

There are two sources of heat rise in a supercharger. One is the simple heat rise of the work of compressing the air/intake charge even assuming the compressor is 100% efficient. 
The other is the fact that most pre-WW II and WW II superchargers were not very efficient. If 70% of the power applied to the input shaft of the supercharger actually went to compressing the air it was a very good supercharger indeed in early WW II. The other 30% of the power didn't just disappear. All but a tiny percentage (under 1% for friction) went into heating the air over and above the heating done in actually compressing the air. You wound up with some _very_ hot air going into the engine.

A supercharger that was 65% efficient saw 35% of the power applied to the input shaft turned into excess heat of the intake air/charge and so on for lower efficiencies. 

the power needed to turn the supercharger impeller was proportional to the speed of the impeller (or more properly to the speed of the tips but if we are talking about the same supercharger the impeller speed will do). Obviously reducing the impeller speed will require much less power and also much less power going into heating the intake charge. 
The supercharger on the Merlin VIII engine was the same as the Merlin III except it used a set of 6.313 gears instead of 8.588 gears the overall change was an increase in take-off power 50 1080hp at 3000rpm using 5 3/4lb boost. Less power used to turn the supercharger, throttle plate open further reducing pumping loss and a much cooler/denser intake charge. trade of was engine topped out at 1275hp at 3000rpm at sea level suing 9lbs of boost. 

The heat of compressing the air, especially when factoring in the waste heat, rose faster than the outside air temperature dropped with rise in altitude. 

The heat rise of a Merlin XX engine with Hooker supercharger (more efficient than earlier models) was figured to be 148 degrees centigrade at 3000rpm in high gear almost regardless of altitude. at 35,000ft the intake charge temperature in the intake manifold wass about 95 degrees centigrade. In part due to the fact that much less work was being done. Only 84.5lbs of air and fuel per minute going through the supercharger ( and outlet pressure of 26.56 in) compared to the 144lbs at 20,000ft and the output pressure of 48.24in. 

I hope this isn't too confusing. But superchargers, despite only having one moving part are not always simple to figure out

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## varsity07840 (Sep 11, 2020)

If it was such a game changer, why didn't the AAF go for it?


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## Acheron (Sep 12, 2020)

Shortround6 said:


> A difference was the two stage supercharger in the F4F was good for 1000hp at 19,000ft. The same P & W R-1830 when given a turbocharger (and using the same engine driven supercharger) was good for 1200hp at 25,000ft in the last versions of the P-43. It did require a bit more weight and bulk and the turbo (and controller) wasn't really ready for front line use.
> 
> 
> The problem with single stage single speed superchargers is that they can only be optimised for one altitude. The Best engine I know of for illustrating this is the Merlin. The Merlin III used in the Hurricane I Spitfire I and a several other British aircraft would hold 6lbs of boost (around 42in ) to 16,250 ft with the engine turning 3000rpm which spun the impeller at 25,764rpm.
> ...


I am not a technical minded person sadly, but what I take from this is that " single stage single speed superchargers is that they can only be optimised for one altitude". Though two questions:
1) "single-speed", I would assume that if your supercharger could work at different speeds, it meant that it could compress the air to different levels, making it more flexible at different altitudes, no?
2) What is a "stage" in a supercharger? I would assume that two-stage superchargers supercharge the air twice, essentially running it through one compressor first and then through a second one. Or skip the second if for example the aircraft is at a lower altitude where this would not be helpful.

Sorry for such basic questions, but apart from not being technically minded, you undoubtedly noticed that English is not my first language. I can do reasonably well in conversations (I hope), but technical subjects get confusing.


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## Shortround6 (Sep 12, 2020)

To answer,
1, you are correct. there were a number of 2 speed superchargers. a gear change mechanism allowed for two optimum altitudes. Merlin X engine used the same supercharger as the III and VIII but used different gear ratios and the pilot had a choice. Some aircraft used a variable drive but only between certain limits. No 3 speed supercharger every made it to service in any numbers. 
2. again you are correct, except for the last part which you have a bit backwards. the first compresser is the one that could be skipped on some aircraft. On a turbocharged aircraft the air still went through the compressor before going to the engine driven supercharger, the compressor in the turbo just wasn't spinning very fast. All turbocharged aircraft used two compressors in series. 

problem with two stage superchargers is the intake charge gets really hot, several hundred degrees more than a single stage so some method of cooling the intake air/charge is needed or the extra compression of the 2nd stage is largely wasted (air is less dense and less manifold pressure can be used before detonation sets in)

detonation (like knocking in a car only much worse) has quite a number of factors but for our understanding it is the fuels ability to not spontaneously combust as the piston is rising in the cylinder before the spark plugs ignite the fuel/air mixture. low octane fuel will ignite before high octane fuel in the same conditions of which the pressure and temperature of the mixture are the most important. This is why all the talk and interest in intercoolers and aftercoolers and water injection, anything that would help cool the intake charge allowed higher boost as it helped keep the temperature down.

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## MIflyer (Sep 12, 2020)

I believe the first P-38 to see actual combat was an F-4 recon bird. Despite having an engine shot out over the Pacific, the Lightning outran the Japanese fighter anyway. 

By the way, I wrote an article about recon P-38's and had the editor of Aviation History tell me that airplane was not the first P-38 in combat because it did not have guns!

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## MIflyer (Sep 12, 2020)

The XP-41 was an attempt to produce a "better" P-35, getting rid of that horrible MLG and generally cleaning up the airplane. But it used a 2 stage mechanically supercharged R-1830, like the F4F. Seversky had a better idea and built at his own cost the AP-4, which was basically an XP-41 with a turbosupercharger in the large baggage compartment. The XP-41 was slower than the P-40 and lost that competition but the AP-4 impressed the Air Corps and led to the P-43 as the production version. Then scale up the P-43 by about 50% and you've got a Thunderbolt.

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## GregP (Sep 12, 2020)

Hi Miflyer,
1) If the P-38 in question was getting shot at, I submit it WAS in combat, whether or not it could return fire. If that isn't the case, then I suppose a C-47 that got shot down wasn't in combat either. I bet any survivors would dispute that it wasn't in combat! But, an editor usually has the power to say whatever they want to say and make it stick.
2) What is MLG? Main Landing Gear? I kind of like the P-35 landing gear because there was very little damage in the event of a gear-up landing and, since retracting landing gear was somewhat "new" when the P-35 came out, there were a LOT of gear-up landings. I think it was only when the advanced trainers got retractable gear (I'm thinking AT-6) that they began to be less of an issue because new fighter pilots were already used to raising and lowering landing gear. But ... I agree the XP-41 DOES look better than the P-35.

Cheers.

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## CORSNING (Sep 12, 2020)

Slightly off topic but, the following comes from page 147, AHT by Francis
H. Dean:

*Dec. 7 '41* USAAF inventory of P-38s at the time of Pearl Harbor is
69 in active service including some D models; the only unit fully
equipped is the First Pursuit Group, Selfridge Field.
*Dec. 8 '41 *Initial elements of the First Pursuit Group from Selfridge
arrive at Sand Diego to defend the west coast from Japanese attack.
Group movement is complete by December 22, 1941.
*Apr. 7 '42 *F-4 Photo Lightnings of Flight A, 8th Photo Squadron
with 75 gallon drop tanks arrive in Australia under Maj. K. Prolifka
and* by April 16 *start reconnaissance missions over eastern New
Guinea and New Britain. These are the first Lightnings in the
Pacific. Later F-4s operate very successfully with the 435th
Bombardment Squadron.

2 more cents worth.


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## MIflyer (Sep 12, 2020)

GregP: Yep, I thought that was a ridiculous comment to make, especially from a publication that prides itself on accuracy. Aviation History has experts in the appropriate fields review articles for accuracy. The first article I sent them I got a call from an author who asked me why I thought George fighters had attacked two USN PB4Y-2's instead of the Tojos that had been accepted. I explained that the noted Japanese author Henry Sakida had confirmed that and even confirmed the two kills the USN airplanes claimed.

The P-35 Main Landing Gear had those huge "airscoops" when the gear doors came down. I am amazed they could even stay in the air long enough to get on the ground. 

I think that if you have been shot at you have been in combat and if you've been hit and lost an engine you sure have. I guess all those Liberty ships that were sunk were never in combat.

I sent that article to Air Classics and they published it withiout even tell me they were doing so in advance - and they never paid me for it. Since it was a tribute to a friend of mine, I really did not care too much if I got paid.
You can read it at: 9th Photo Reconnaissance Squadron

CORSNING: Yes, that matches my info as well. The F-4's sure got into it early. We did not have a better recon aircraft for some time.

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## P-39 Expert (Sep 13, 2020)

Shortround6 said:


> The P-38 was in combat or in combat areas in Aug of 1942.
> July 31st the 27th squadron stays in Iceland as a defensive unit, relieved by the 50th Squadron Aug 26th and continues on to England.
> Aug 9th two P-38s claim to Japanese flying boats in the Aleutian Islands.
> Aug 22 the 67th squadron with a mix of P-38s and P-39s arrives at Henderson Field.
> ...


Regarding the P-38 there were a few P-38s on station around the world in the last half of 1942, but most historians say that Operation Torch in November '42 was their European debut. They began operating in strength in the Pacific in December '42. Vast majority of 1942 was fought with the P-39, P-40 and F4F.

Weight could have been easily reduced in the P-40 and F4F by deleting two of the six .50cal MGs. This would have saved around 350# per plane. Climb would have increased on the order of 400 feet/minute which both the P-40 and F4F sorely needed. The P-40E could barely reach 20000' and the F4F pilots bitterly complained when the two .50cal MGs were added saying that the previous F3F with four MGs climbed and handled much better.

The P-39D/F/K/L would have lost around 300# by deleting the four useless .30cal MGs in the wings (200#) and the nose armor (100#) which didn't protect anything. This increased climb by about 360fpm which would have allowed those early P-39s to outclimb the contemporary Zeros. P-39s already enjoyed a 40mph speed advantage up to 25000' over the Zero. The remaining 37mm cannon and two .50cal MGs left plenty of firepower as the Russians proved against the Luftwaffe.

Four .50cal MGs were plenty anyway. The AAF was already going to four MGs in their newer P-51A/B/C Mustangs. The USN was using 4 .50cal MGs in their newer FM2 Wildcats and F8F Bearcats.


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## MIflyer (Sep 13, 2020)

The P-40D had four .50 cal guns and RAF Ace Caldwell, I believe it was, preferred it that way. There was a case where he was covering a convoy and two 109's came down out of the Sun and hit him good. He turned around, shot down one of the 109's and sent the other one packing.

Deleting the four .30 cal would have decreased the value of the P-39 for strafing, and on the 'Canal it w as sorely needed for that. The Marines credited the P-400's of the 67th with saving Henderson Field with their close support. And I think deleting the 37MM and putting in a third .50 cal would have been a good idea for optimized air to air P-39's. With the "roman candle" firing rate of the cannon, the chance of hitting anything with the 37MM other than a bomber going straight and level was pretty slim and its trajectory was so different from that of the .50 cal and .30 cal that hitting something other than the ground with all three was unlikely.

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## Greg Boeser (Sep 13, 2020)

Interestingly, local practice was to mount extra guns in the factory designed four gun models of the P-40. (P-40L, M, early N) The wings had the mounts already, and the pilots preferred the extra firepower.
It is true that the USN complained about the 6 gun F4F-4. It used the same engine as the F4F-3, but the added guns, armor, and folding wing mechanism increased the weight by over 500 lbs. The Navy pilots were most upset about the decrease in firing time from 34 second to 20 seconds. The FM-1 and FM-2 returned to the four gun armament.

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## Shortround6 (Sep 13, 2020)

The benefit of the four gun armament in the F4F and perhaps the P-40 rather depends on how the planes were loaded. 

The F4F-3 was listed as having 286lbs worth of guns with 360 lbs of ammo (300rpg) 'standard' and 516lbs of ammo (430rpg) in overload condition. 

The F4F-4 was listed as having 288.7lbs worth of guns (four guns )with 240 lbs of ammo (200rpg) 'standard' or 422lbs worth guns (six guns) and 432lbs of ammo (240rpg) in overload condition. 

Please note that an F4F-3 with 430rpg was carrying about 54 lbs less weight than an f4F-4 with six guns and 240rpg. 

The P-40D was likewise designed with a ridiculous amount of ammo capacity, but since only about 30 were built ( I don't know how many British planes showed up with only 4 guns) 

we have a weight of 256lbs for 4 guns * and 300lbs for 250rpg designed weight capacity but the ammo bins would hold 738lbs of ammo (620 rpg) in overload condition. 

The P-40E had a design load of 384lbs worth of guns (six) and 423lbs worth of ammo (235rpg) amd an overload of 561lbs of ammo (1870 rounds total).

Please note the "design" fuel load (for design gross weight) was 120 US gallons of fuel while overload included both an extra 25.5 gallons in the fuselage tank plus the drop tank. 

Please remember that both the F4F-4 and the P-40D/E were _ordered _in the summer of 1940 and the high rate of fire M2 gun had not yet been approved. 

For the WIldcat if you pulled the two extra guns but loaded in the extra ammo to extend the firing time you are not going to see much of change in performance. 

Some of the light weight P-40s resorted not only to four guns but 235rpg or even 201 rounds per gun. Which is why they gained weight in squadron service. By the time they were in service they were no longer tasked (at least not often) with the high performance interceptor role.

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## Shortround6 (Sep 13, 2020)

Greg Boeser said:


> but the added guns, armor, and folding wing mechanism increased the weight by over 500 lbs. The Navy pilots were most upset about the decrease in firing time from 34 second to 20 seconds. The FM-1 and FM-2 returned to the four gun armament



According to figures in AHT the F4F-4 gained almost 300lbs in the wing alone. 

I have no idea if that was due to modifications to fit the extra guns (the guns are not counted in the weight of the wing) the hinge mechanism, general beefing up to handle higher gross weights or some combination of those factors or others, however, once the structural weight is there the squadron mechanics cannot take it out. They can yank two of the guns and limit the ammo but the extra 300lbs is going to remain.


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## Vincenzo (Sep 13, 2020)

Shortround6 said:


> According to figures in AHT the F4F-4 gained almost 300lbs in the wing alone.
> 
> I have no idea



folding wing


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## MIflyer (Sep 13, 2020)

The P-39 could theoretically carry 2000 rounds of .30 cal ammo. On the 'Canal they probably liked that capability for ground attack.

Yes, lots of heavy parts in the F4F and FM-1 folding wing.


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## Greg Boeser (Sep 13, 2020)

Shortround6 said:


> The benefit of the four gun armament in the F4F and perhaps the P-40 rather depends on how the planes were loaded.
> 
> The F4F-3 was listed as having 286lbs worth of guns with 360 lbs of ammo (300rpg) 'standard' and 516lbs of ammo (430rpg) in overload condition.
> 
> ...


There is always the question of how a plane is loaded. Geoff Fisken reported that to improve the chances of survival in the Buffalo, they stripped them of all excess weight and reduced the ammo to about 5 seconds worth. They had learned that they were only going to get one pass at the enemy, and adapted accordingly.


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## GrauGeist (Sep 14, 2020)

The PT boat guys sure liked it when the AAF guys got rid of the Oldsmobile 37mm, they used that on their boats and it was such a hit, later PT boats were manufactured with the 37mm as standard equipment.

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## Stig1207 (Sep 14, 2020)

MIflyer said:


> The P-40D had four .50 cal guns and RAF Ace Caldwell, I believe it was, preferred it that way. There was a case where he was covering a convoy and two 109's came down out of the Sun and hit him good. He turned around, shot down one of the 109's and sent the other one packing.



The story goes that it was Werner Schoer that shot up his plane and wounded Caldwell, but he turned around and shot down Schoer's wingman and sent Schoer packing. However, the only part that has any basis in fact is the bit where Schoer shot up Caldwell 's P-40 and wounding him.

There is a Hollywood movie gone begging in Clive Caldwell's exploits.

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## P-39 Expert (Sep 14, 2020)

MIflyer said:


> The P-40D had four .50 cal guns and RAF Ace Caldwell, I believe it was, preferred it that way. There was a case where he was covering a convoy and two 109's came down out of the Sun and hit him good. He turned around, shot down one of the 109's and sent the other one packing.
> 
> Deleting the four .30 cal would have decreased the value of the P-39 for strafing, and on the 'Canal it w as sorely needed for that. The Marines credited the P-400's of the 67th with saving Henderson Field with their close support. And I think deleting the 37MM and putting in a third .50 cal would have been a good idea for optimized air to air P-39's. With the "roman candle" firing rate of the cannon, the chance of hitting anything with the 37MM other than a bomber going straight and level was pretty slim and its trajectory was so different from that of the .50 cal and .30 cal that hitting something other than the ground with all three was unlikely.


Strafing ground troops was about all the .30cal MG was good for, it certainly wasn't effective against other planes. It wasn't good enough for any other contemporary US fighter. 

The 37mm cannon had a flat trajectory out to about 400 yards which was about the outer edge of accuracy for any guns air to air. Soviets liked it. 

Substituting a .50cal MG for the 37mm wouldn't have provided enough firepower and it would have screwed up the balance. Better to substitute a 20mm cannon with a bigger ammunition tray.


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## GrauGeist (Sep 14, 2020)

Sorry to disagree, but a .30 (or .303) will easily pass through aluminum, penetrate fuel tanks, sever flight controls and so on.

Saburo Sakai was nearly killed by a .30 caliber bullet from an SBD that penetrated his cockpit, so be careful about discounting it.

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## P-39 Expert (Sep 14, 2020)

GrauGeist said:


> Sorry to disagree, but a .30 (or .303) will easily pass through aluminum, penetrate fuel tanks, sever flight controls and so on.
> 
> Saburo Sakai was nearly killed by a .30 caliber bullet from an SBD that penetrated his cockpit, so be careful about discounting it.


I enjoy the debate. .30s were worthless against armored German planes. May have been of limited use against unarmored Japanese planes. If four .50s was adequate, then a 37mm and twin .50s were certainly adequate. Lose the .30s and outclimb the contemporary Zero. Big advantage.

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## Shortround6 (Sep 14, 2020)

Hmmmm, American .30 cal was worthless. 

Japanese 7.7mm in Ki 27s, Ki 43s and cowl guns in A6M shot down how many american planes?
British ,303s (actually same round as the Japanese 7.7) shot down how many German aircraft in 1939-41?

American .30 cal has 13% more kinetic energy than Japanese 7.7mm.
British kept four .303 guns in the Spitfire until 1944?in part because the 20mm ran out of ammo before the .303s. 

The 37mm was notorious for jamming in the early versions. with a 30 round ammo supply it was good for about 12 seconds of firing time.

if the 37 jams or is out of ammo the P-39 had the fire power of a P-40C if it kept the .30 cal guns. Without them?????

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## MIflyer (Sep 14, 2020)

An article I found said that the underwing .50 cal guns on the later P-39's really screwed up the handling and caused it to be actually slower than the earlier models. We have some evidence that some Soviet P-39's had the underwing .50 cal guns removed.

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## MIflyer (Sep 14, 2020)

Shortround6 said:


> British kept four .303 guns in the Spitfire until 1944?in part because the 20mm ran out of ammo before the .303s.


 
Good Point! And the RAF pressed hard to get .50 cal guns installed to replace the .303 in Spitfires in time for the Normandy invasion because so many Spits would be required for fighter bomber duties.


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## P-39 Expert (Sep 14, 2020)

Shortround6 said:


> Hmmmm, American .30 cal was worthless.
> 
> Japanese 7.7mm in Ki 27s, Ki 43s and cowl guns in A6M shot down how many american planes?
> British ,303s (actually same round as the Japanese 7.7) shot down how many German aircraft in 1939-41?
> ...


37mm jamming was fixed in early/mid '42 with the K model (Bell model 26) which provided the small exit vents in the nose to exhaust heated cockpit air ducted into the gun bay. This prevented the gun from freezing at altitude. Soviets considered the 37mm very reliable and more reliable than the 20mm. 

If the Japanese twin .30s shot down so many American planes then the twin .50s in the P-39 made short work of unarmored Zeros. 

The British moved forward with the 20mm cannon because the .30s weren't powerful enough, even though there were eight of them. Spitfires with 20mm cannons held 120 rounds, about 12 seconds firing time. P-38s with one 20mm cannon had 150 rounds which was only about 15 seconds firing time. 

Whole purpose of losing the .30s (and nose armor) was to improve climb and combat ceiling (1000fpm). If Zeros could get above you then your 40mph speed advantage was worthless. If you could get above them then you had every advantage except turn.

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## GrauGeist (Sep 14, 2020)

P-39 Expert said:


> 30s were worthless against armored German planes.


But the Germans used a fixed 7.92mm MG (MG17) for their aircraft's armament during the early part of the war: Bf109, Fw190, He112, Bf110, Ju87, etc.

The MG17 was literally a .31 caliber MG, so how were the Germans able to overcome the British armor, then?


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## P-39 Expert (Sep 14, 2020)

MIflyer said:


> An article I found said that the underwing .50 cal guns on the later P-39's really screwed up the handling and caused it to be actually slower than the earlier models. We have some evidence that some Soviet P-39's had the underwing .50 cal guns removed.
> 
> View attachment 594907


Just a couple of errors in this article, all in the last paragraph. No -35 engines in any Q models. All N/Q models had the -85 engine with 1200hp for takeoff and 1125hp at 15500'. 

The 1150hp -35 was used in the P-39C/D/D-1/F models. The -63 with 1325hp (takeoff) was used in the D-2/K/L models. The -83 was used in the M and differed from the -85 only in reduction gear ratio. Power section was the same.

If that $22854 unit price in the last contract was correct then the Q was quite a bargain.

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## P-39 Expert (Sep 14, 2020)

GrauGeist said:


> But the Germans used a fixed 7.92mm MG (MG17) for their aircraft's armament during the early part of the war: Bf109, Fw190, He112, Bf110, Ju87, etc.
> 
> The MG17 was literally a .31 caliber MG, so how were the Germans able to overcome the British armor, then?


The Germans replaced the .30cal MGs with the 13mm (.50 caliber) MG for their 109G-6 and 190A-6. They apparently thought the .30s were not powerful enough.


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## GrauGeist (Sep 14, 2020)

WWI aircraft weapons were in the .30 caliber range (.30 to .32) as were the majority of fighter's armament in the interwar years. It wasn't until the late 1930's that the U.S. started adopting the .50 - and even then, it was a combination of one .30 MG and one .50 MG. The SBD was one of the first production U.S. aircraft that was equipped with two fixed foreward .50 MGs.

The escalation of heavy calibers follows the natural progression of warfare: over-power the enemy.

Otherwise, fighters would not have been equipped with higher output engines and better protection, tanks would not have been up-gunned and up-armored, Battleships and Cruisers would not have had larger guns and faster speeds and infantry would still have been armed with bolt-action rifles.

The idea of having more MGs or heavier caliber MGs and/or cannon was to insure downing the enemy regardless of the enemy's protection. The Luftwaffe wasn't arming their Sturmbocks with cannon because they thought the B-17 was so well armored (because it wasn't), they did it because they wanted to bring the B-17 down as quick as possible.

As mentioned before, the .30 (or .31, etc.) will penetrate aluminum skin, stringers, spars, control lines, fuel tanks, supply lines, engine components, glass/perspex, and so on - which is the VAST majority of an aircraft presented. Pilot and engine armor is just a small portion and it will not prevent an aircraft for being damaged beyond function.

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## MIflyer (Sep 14, 2020)

I have read that for the Hawk 81A's the RAF used in North Africa they removed the two .50 cal nose guns and replaced them with .303 guns. The reason was logistics; the .303 round was standard for British forces in the air, on the ground and at sea.

I also read where during the BoB they took a section of Spitfire armor plate and fired a .303 round into it to demonstrate to the pilots that they had some protection. . The round went through the armor like it was balsa wood.

By the way, I would assume the price for a P-39Q did not include the V-1710 engine, radios and guns, all of which would have been GFP.

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## tomo pauk (Sep 14, 2020)

MIflyer said:


> By the way, I would assume the price for a P-39Q did not include the V-1710 engine, radios and guns, all of which would have been GFP.



Yes, the price of complete aircraft was around 50000 $ (similar with P-51; the P-40 dropped to ~45000 by 1944).

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## GrauGeist (Sep 14, 2020)

MIflyer said:


> I also read where during the BoB they took a section of Spitfire armor plate and fired a .303 round into it to demonstrate to the pilots that they had some protection. . The round went through the armor like it was balsa wood.


Several years ago, my friends and I were at the range and they were plinking at a 5/16" thick steel target with their .223s set up aboit 35 yards out.
It would ring like a bell with their hits. Being a smartass, I got out my 7x57 Mauser and took a shot. The target didn't move - ok, so I missed, no problem, took more careful aim and let fly. Again, nothing - I missed again??
Baffled, I went out and looked at the target. Scores of divots from the .223 impacts and lo and behold: two large holes near the center. The 7x57 passed through it like it was cardboard...

.30 caliber rounds can and will do damage.

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## tomo pauk (Sep 14, 2020)

If anyone is interested - the 'flyaway' cost of some USAAF A/C:

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## P-39 Expert (Sep 14, 2020)

GrauGeist said:


> Several years ago, my friends and I were at the range and they were plinking at a 5/16" thick steel target with their .223s set up aboit 35 yards out.
> It would ring like a bell with their hits. Being a smartass, I got out my 7x57 Mauser and took a shot. The target didn't move - ok, so I missed, no problem, took more careful aim and let fly. Again, nothing - I missed again??
> Baffled, I went out and looked at the target. Scores of divots from the .223 impacts and lo and behold: two large holes near the center. The 7x57 passed through it like it was cardboard...
> 
> .30 caliber rounds can and will do damage.


And there are accounts from British pilots in the BoB of emptying their entire magazines of eight .30cal guns into a single He111 and watching it fly on to the target. Now I much prefer actual documented tests to anecdotal stories but if the .30cal gun was sufficient then the .50cal, 20mm, 30mm, 37mm guns would not have been developed. And the .30cal MG would have been used on AAf fighters, which it was not, except for the P-39.


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## Acheron (Sep 14, 2020)

GrauGeist said:


> Several years ago, my friends and I were at the range and they were plinking at a 5/16" thick steel target with their .223s set up aboit 35 yards out.
> It would ring like a bell with their hits. Being a smartass, I got out my 7x57 Mauser and took a shot. The target didn't move - ok, so I missed, no problem, took more careful aim and let fly. Again, nothing - I missed again??
> Baffled, I went out and looked at the target. Scores of divots from the .223 impacts and lo and behold: two large holes near the center. The 7x57 passed through it like it was cardboard...
> 
> .30 caliber rounds can and will do damage.


Careful! I am an amateur, but I am stumbling over the 35 yards (32 meters). From the stories about the RAF gun convergence debate, typical engagement ranges seemed to be around 750 feet (~225 meters). Doesn't that make a considerable difference in how much energy the bullet will retain?


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## MIflyer (Sep 14, 2020)

Yes, in both the Spitfire armor "test" and the gun range test they were firing from a lot closer than actual combat, where 200 yards would have been considered to be "close."


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## glennasher (Sep 14, 2020)

GrauGeist said:


> Several years ago, my friends and I were at the range and they were plinking at a 5/16" thick steel target with their .223s set up aboit 35 yards out.
> It would ring like a bell with their hits. Being a smartass, I got out my 7x57 Mauser and took a shot. The target didn't move - ok, so I missed, no problem, took more careful aim and let fly. Again, nothing - I missed again??
> Baffled, I went out and looked at the target. Scores of divots from the .223 impacts and lo and behold: two large holes near the center. The 7x57 passed through it like it was cardboard...
> 
> .30 caliber rounds can and will do damage.




In 5/16 steel, even a pistol load will ding the heck outa them. Back in the waybackwhens, I was casting bullets for a .41 Magnum revolver, and tried some of them (a fairly light bullet, even!) and it dimpled the heck out of the steel. We normally shot 9mm and .45 ACP at them, but since they were there, and I had that .41, I thought it might be interesting to see what happened. I quit after seeing how much damage that .41 did. The lead bullets were cast out of wheelweights, nothing special at all, and ran IIRC, about 190gr. I used the powder charge I normally used with 225gr. bullets, they weren't even a "hot" load.

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## GrauGeist (Sep 14, 2020)

Acheron said:


> Careful! I am an amateur, but I am stumbling over the 35 yards (32 meters). From the stories about the RAF gun convergence debate, typical engagement ranges seemed to be around 750 feet (~225 meters). Doesn't that make a considerable difference in how much energy the bullet will retain?


35 yards (32 meters) was a "for fun" distance at the gun range.

The point being, that the .223 (about 55 gr.) was just putting slight dents in the steel while making the target ring and dance and when I shot the target with my 7x57 (about 157 gr.), the target did not make a sound nor did it move. The bullet passed through it as if it were a paper target and this was a standard hunting round not an AP.

This illustrates the energy of a 7mm (.30) caliber projectile and while that was slightly tempered steel at close range, it would have easily penetrated and or damaged an aluminum structure at distances seen in aerial combat.


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## GrauGeist (Sep 14, 2020)

P-39 Expert said:


> And there are accounts from British pilots in the BoB of emptying their entire magazines of eight .30cal guns into a single He111 and watching it fly on to the target. Now I much prefer actual documented tests to anecdotal stories but if the .30cal gun was sufficient then the .50cal, 20mm, 30mm, 37mm guns would not have been developed. And the .30cal MG would have been used on AAf fighters, which it was not, except for the P-39.


Were they hitting the engines, wings and cockpit or were they emptying their entire magazines on the fuselage/tail?
What angle were they attacking at?
Were they even hitting it at all?

Plenty of evidence that .303s were effective (seen by wrecks scattered all over England) to question pilots reporting that they were not bringing down unarmored bombers after exhausting their entire loadout of ammo.


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## glennasher (Sep 14, 2020)

Frankly, I'm surprised that the 5.56/.223 didn't zip right thru the steel. We had a saying "velocity penetrates steel" and it almost always worked. Even the piddling .17HMR will ding the heck out of steel, at only 2550fps/muzzle velocity. Then again, I've seen 5 ton truck tires at 200 yards with ball M193 (5.56) looking like a porcupine while still full of air, lol. Sometimes even 7.62mm NATO wouldn't penetrate those tires, so who knows?


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## jmcalli2 (Sep 14, 2020)

Shortround6 said:


> Most of the requirement/s were the same. However the requirement that led to the P-38 wanted_ one hour more endurance _at the same speed/altitude (actually double from one hour to two hours) than the requirement that led to the P-39. It was the weight/bulk of the extra fuel that that made the P-38 so much larger. The specification might have been meet by single engine aircraft had a 1500hp single engine been available at the start of design. Such an engine was not available requiring the use of two 1000hp engines which made the proposed plane even larger.
> What led to the P-39 was never intended to have the endurance of the requirement that led to the P-38.
> 
> 
> ...



The path Bell took was to keep the power up at over 20,000+ feet. I'd read that the XP-39 hit 390mph at 20,000 ft even though the turbo was less than optimal. Power + altitude = speed because drag is less important in thinner air over 20,000 than at 12,000. NACA proposed reducing drag to get 400+ projected at 10,000 to 15,000 feet without the turbo. Since the P-40 was struggling to hit 340 at these altitudes and the XP-38 was over 400mph above 20,000 ft it seemed a no-brainer.


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## jmcalli2 (Sep 14, 2020)

MIflyer said:


> A common misconception, often repeated. I have even seen clueless but successful writers say something like, "In isolationist America the Army wanted to focus on ground attack aircraft to defend the beaches in case of an invasion." POPPYCOCK!
> 
> In reality the USAAF was totally focused on the turbo as a first stage supercharger for a a two stage system. They even tried the turbo on the P-36/40 airframe, to produce the XP-37 - and it worked, adding 50 mph speed at higher altitudes, as long as you did not want the pilot to be able to see anything from that cockpit way back in the tail.
> 
> ...



The US was moving towards turobsupercharging because it promised "free" boost; no power drain to compress induction air, just energy that was being wasted. Despite the problems, it must be considered a successful step when you look at the P-38, P-47, B-17, B-24, B-29, B-32, and B-36.

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## GrauGeist (Sep 14, 2020)

glennasher said:


> Frankly, I'm surprised that the 5.56/.223 didn't zip right thru the steel. We had a saying "velocity penetrates steel" and it almost always worked. Even the piddling .17HMR will ding the heck out of steel, at only 2550fps/muzzle velocity. Then again, I've seen 5 ton truck tires at 200 yards with ball M193 (5.56) looking like a porcupine while still full of air, lol. Sometimes even 7.62mm NATO wouldn't penetrate those tires, so who knows?


The 5/16" plate wasn't mild steel, it had a slight temper to it, as it was a remnant from stock used for gussets on a Caterpillar's carapace - which is why it had a sweet ring to it when the .223s struck it!


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## GregP (Sep 14, 2020)

Hi Jmcalli2,

We have entire threads about the XP-39 and almost nobody believes it really hit 390 mph. There doesn't seem to be any flight test data to surface that confirms that speed as yet.

I have a copy of a book with that data (390 mph) in it from 1946 and reissued unchanged in 1964. The book is, "U.S. Army Aircraft 1908 - 1946 SC-AEF-AAS-AAC-AAF, by James C. Fahey, published by Ship and Aircraft, P. O. Box 48, Falls Church, Virginia, 22046. The 390 mph claim is on page 33. The XP-39E is shown at 386 mph on the same page.

My copy must be from the 1964 reissue because there is a ZIP code in my copy and ZIP Codes were adopted in 1963.

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## MIflyer (Sep 14, 2020)

jmcalli2 said:


> The US was moving towards turobsupercharging because it promised "free" boost; no power drain to compress induction air, just energy that was being wasted. Despite the problems, it must be considered a successful step when you look at the P-38, P-47, B-17, B-24, B-29, B-32, and B-36.



Only the USAAF employed two-stage supercharged heavy bombers with high altitude capability as "the norm." While the USAAF heavy bombers took some heavy losses, the losses would have been crippling had they not had that capability. The USN used some B-17's and B-24's with that capability only because that was what was coming off the production line; on their dedicated USN version of the B-24, the PB4Y-2, they removed the turbos because they did not need that capability. 

When the RAF needed some ECM aircraft they knew just where to go; they used B-24's and B-17's. The altitude capability enhanced the jamming coverage and also enabled them to better avoid a Luftwaffe that might be annoyed by their activities.

Oddly enough the USN, having introduced the two stage supercharged fighter to combat, abandoned the concept. The F7F and F8F used single stage supercharged engines, as did the last production Wildcat, the FM-2. After all, they had figured out that the only high altitude bombers they would encounter were on their side.

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## P-39 Expert (Sep 14, 2020)

MIflyer said:


> Only the USAAF employed two-stage supercharged heavy bombers with high altitude capability as "the norm." While the USAAF heavy bombers took some heavy losses, the losses would have been crippling had they not had that capability. The USN used some B-17's and B-24's with that capability only because that was what was coming off the production line; on their dedicated USN version of the B-24, the PB4Y-2, they removed the turbos because they did not need that capability.
> 
> When the RAF needed some ECM aircraft they knew just where to go; they used B-24's and B-17's. The altitude capability enhanced the jamming coverage and also enabled them to better avoid a Luftwaffe that might be annoyed by their activities.
> 
> Oddly enough the USN, having introduced the two stage supercharged fighter to combat, abandoned the concept. The F7F and F8F used single stage supercharged engines, as did the last production Wildcat, the FM-2. After all, they had figured out that the only high altitude bombers they would encounter were on their side.


The F8F and FM-2 were also lighter than their predecessors so they didn't need a two stage supercharger. The Bf109 and Zero were good at altitude with a single stage supercharger.


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## Shortround6 (Sep 14, 2020)

The weight of the planes was only part of puzzle. The fact the F8F had an improved supercharger had a lot to do with it.

edit, not all single stage superchargers were the same and the state of the art in single stage superchargers did get better as the war went on. The improvements were not as dramatic as adding a 2nd stage but they did exist. 

For the FM-2 the version of the Cyclone that was used in it offered 1000hp at 17,000ft which more than split the difference between the Cyclone in the Martlet I (1000hp at 13,500ft) and the P & W two stage engine in the F4F-4 and FM-1, 1000hp at 19,000ft. An empty FM-2 was over 300lbs lighter than F4F-4 so there was an advantage even before we start argueing about guns/ammo, etc. 

The early F8F-1s got R-2800s that offered 1600hp at 16,000ft compared to the 1600hp at 13,500ft that the engines in the B-26 and Lockheed Venturas offered. 
Late production F8F-1s got R-2800s that offered 1700hp at 16,000ft and F8F-2s wound up with single stage engines that gave 1600hp at 22,000ft. 

Two stage engine in early F4Us and F6Fs gave 1800hp at 15,500ft and 1650hp at 22,500ft.


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## wuzak (Sep 15, 2020)

P-39 Expert said:


> The P-39D/F/K/L would have lost around 300# by deleting the four useless .30cal MGs in the wings (200#) and the nose armor (100#) which didn't protect anything. This increased climb by about 360fpm which would have allowed those early P-39s to outclimb the contemporary Zeros. P-39s already enjoyed a 40mph speed advantage up to 25000' over the Zero. The remaining 37mm cannon and two .50cal MGs left plenty of firepower as the Russians proved against the Luftwaffe.






P-39 Expert said:


> Substituting a .50cal MG for the 37mm wouldn't have provided enough firepower and it would have screwed up the balance. Better to substitute a 20mm cannon with a bigger ammunition tray.



So, changing the 37mm for a 0.50" would have screwed up the balance, but removing 100lbs of armour from the forwardmost part of the fuselage would not?


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## P-39 Expert (Sep 15, 2020)

wuzak said:


> So, changing the 37mm for a 0.50" would have screwed up the balance, but removing 100lbs of armour from the forwardmost part of the fuselage would not?


Bell was able to maintain balance when the 20mm cannon was substituted for the 37mm cannon, a difference of 140# including ammunition. A .50cal MG with 200 rounds of ammunition would weigh about 140# for a difference of about 160# vs the 37mm cannon. So yes, they probably could have done it. Should have been able to remove the 100# of armor plate and maintain balance also with the 37mm.

But substituting a .50cal MG for either cannon would have been a substantial loss of firepower. The Navy calculated that a 20mm cannon was equivalent to three .50cal MGs. The substitution would mean only three .50cal MGs remained (actually only about 2.5 considering the loss due to synchronization of the original two). All the other AAF and USN fighters had at lease 4 .50cal MGs. Better to leave either cannon with the two synchronized .50s and have the equivalent of 4.5 .50cal MGs. Centerline fire of all three weapons helped also. Just my opinion.

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## MIflyer (Sep 15, 2020)

I think that a .50 cal with late war API was at least as good as a 20MM for fighter vs. fighter WW2 combat.

Of course you would have to add weight forward to handle the CG problem. Add more ammo to the .50 cal and move some radios and the IFF from aft of the cockpit.
By the way, P-39's in the Pacific usually seem to have a box under the canopy aft of the cockpit. The radio compartment was aft of the engine, so I assume that extra box was the SCR-695 IFF.

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## Shortround6 (Sep 15, 2020)

MIflyer said:


> Oddly enough the USN, having introduced the two stage supercharged fighter to combat, abandoned the concept. The F7F and F8F used single stage supercharged engines, as did the last production Wildcat, the FM-2. After all, they had figured out that the only high altitude bombers they would encounter were on their side.








.Used in the F4U-5 postwar

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## P-39 Expert (Sep 15, 2020)

MIflyer said:


> I think that a .50 cal with late war API was at least as good as a 20MM for fighter vs. fighter WW2 combat.
> 
> Of course you would have to add weight forward to handle the CG problem. Add more ammo to the .50 cal and move some radios and the IFF from aft of the cockpit.
> By the way, P-39's in the Pacific usually seem to have a box under the canopy aft of the cockpit. The radio compartment was aft of the engine, so I assume that extra box was the SCR-695 IFF.
> ...


Except that the P-39 was an early war airplane.  How do you figure the .50cal with late war API was as good as a 20mm? Just curious.


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## MIflyer (Sep 15, 2020)

Pilot reports of .50 cal API were very favorable. There were F6F's that shot down Vals with only one round. 

Not a lot of room for radios in a P-39.

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## Peter Gunn (Sep 15, 2020)

If I don't forget when I get back home, I have some pics in a book on the BoB I bought several years ago. In it there are several shots of LW bomber parts being hauled off for scrap with quite a few bullet holes in them. I'll scan it and post it if I remember, but the gist of it is this, you can clearly see in the photos which _holes_ were made by the 20mm and which _dents_ and paint scrapings were made by the .303's. I wouldn't call it a mike drop sort of evidence, just some food for thought.

I have no dog in this hunt, I wouldn't want to be shot at by any of the weapons discussed, but merely thought it might be of interest to the group.

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## Shortround6 (Sep 15, 2020)

Ah, the wondrous American .50 cal 

late war .50 about 800rpm with 43 gram bullet holding about 1 gram of incendiary material
20mm gun about 600rpm with 130 gram projectile holding 10 or more grams of incendiary or HE.

They have nearly identical muzzle velocities. The .50 has a better shaped bullet, the 20mm has more weight per unit of frontal area for better sectional density. Ballistic coefficient does favor the .50 but doesn't really come into play in an realistic air to air scenario (600 yds or under).

The M8 API was introduced in early 44. It was basically a copy of the Russian 12.7mm API round so there was no technical reason it could not have been introduced sooner for "what ifs"
However part of it's value was the incendiary ignited on impact as it was in the nose. It would give a flash on impact indicating the shooter was on target (tracer use was much diminished at this time) however very little incendiary material made it inside the aircraft if it hit anything substantial on the way in (or hit at bad angle).

I would note the examining wrecks or looking at wreck photos needs some interpretation. You can wind up with quite a bit of paint knocked off surrounding a rather small hole. You also have bullets hitting at rather oblique angles making large dents/scraps but no penetration when fired at long ranges. If you have a round "marking" then the bullet hit at a good angle, the more oval or elongated the hole/scrape the worse the angle.


and for instance.




supposed to have been shot down Friday 16th August 1940. in Scotland

Edit, correction, crashed near Worthing in Sussex. No 19 Squadron was equipped with Spitfires with 20mm guns at this time but they were based at Duxford near Cambridge. 

.303s? AA fire? The RAF had how many 20mm armed aircraft in August of 1940 in the North of England and Scotland South coast?

What made the bigger holes?

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## MIflyer (Sep 15, 2020)

The US screwed up when we did not properly copy the MG-34. But I think we really screwed up big time when we did not scale up the .50 cal M-2 to 20MM. The US "experts" said it was not possible. But no one told that to the Japanese and they went ahead and did it. In the Smithsonian they have a sectioned US ,50 cal and a sectioned Japanese 20MM copy sitting side by side. Would have been nice to have the M-39 revolver 20MM in WWII but we copied the action from Mauser and did not get examples early enough.

Most 20MM guns in WWII were copies of the Orkelion, which had its drawbacks.

By the way "single shots" with the .50 cal M2 were possible because in some airplanes there were a few rounds between the ammo bay and the gun. After you were "empty" you could charge the guns and get one round in the chamber to fire. Line up very carefully behind that Val that is about to dive on that poor beat up DD. Pow! Boom! Flamer!

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## P-39 Expert (Sep 15, 2020)

MIflyer said:


> Pilot reports of .50 cal API were very favorable. There were F6F's that shot down Vals with only one round.
> 
> Not a lot of room for radios in a P-39.
> 
> View attachment 595130


Radios were in the tail cone. If you remove the 100lb armor from the nose you only need to remove 100lbs from the tail. Moving the radios up to right behind the pilot/above the engine accomplished that since that was practically on the center of gravity. 

This is just what I have come up with, as I said Bell managed to maintain CG when substituting the 20mm (140lbs lighter) for the 37mm cannon. I don't know exactly how they did it, but they did. In his book "Cobra", Birch Matthews mentioned that in the P-39M the nose armor was no longer needed from a balance standpoint. Since all P-39 airframes were essentially the same one would think that getting rid of that nose armor would have been relatively easy.


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## P-39 Expert (Sep 15, 2020)

Shortround6 said:


> Ah, the wondrous American .50 cal
> 
> late war .50 about 800rpm with 43 gram bullet holding about 1 gram of incendiary material
> 20mm gun about 600rpm with 130 gram projectile holding 10 or more grams of incendiary or HE.
> ...


What is your view on the reliability of the American 20mm cannon? Supposedly it was less reliable than the British version, both copies of the same gun.


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## Shortround6 (Sep 15, 2020)

P-39 Expert said:


> What is your view on the reliability of the American 20mm cannon? Supposedly it was less reliable than the British version, both copies of the same gun.


It was less reliable than the British version (Licence built) to start with as the British had modified theirs due to test results. Americans started with looser tolerances in general and a chamber about 1mm longer (?). The longer chamber allowed the cartridge to move forward when hit by the firing pin, this lead to a light primer strike and misfires. The Americans finally did get it straightened out but it took far to long. The Hispano was also sensitive to mounting, after all, it was designed to be bolted to a roughly 1000lb engine. The P-38s seem to have done OK, in part due the gun being mounted in a rather heavy cradle. Many of the wing guns (or even belly pack guns) did not get this heavy cradle. 

In the US there was quite a bit of finger pointing as the gun makers blamed the ammunition makers and the ammunition makers blamed the gun makers. 

However, as with with any weapon that spanned 6-7 years (first Hispano 404 cannon for the US was shipped in Feb 1938, the Americans did NOT get the Hispano from the British) 
one sentence does not cover the whole situation. Four Companies built a total of 134,638 guns during WW II. after gun number 56,410 the American guns were identical to the British guns for all practical purposes. Which does leave a lot of guns in storage or out in service establishing a bad reputation. The final tally was:

The Navy got....................................21,228 guns
the Army got....................................13,272 guns 
The British got..................................44,474 guns
stored:
...........Servicable...............................19,092 guns
.........UNservicable...........................35,995 guns
Lost or worn out...................................692 guns. (US service?) 

By far the largest producer was Oldsmobile but even they stopped production in Feb 1944. 

This is because the Americans had developed their own lightened, faster firing version called the T-31 of which 32,326 were produced by modifying most of the 35,955 AN M-2 guns held in stock as unserviceable. This started in the summer of 1944.

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## PAT303 (Sep 16, 2020)

P-39 Expert said:


> The Germans replaced the .30cal MGs with the 13mm (.50 caliber) MG for their 109G-6 and 190A-6. They apparently thought the .30s were not powerful enough.



So if the .30's aren't good enough what shot down the 3,000 or so aircraft lost in the BoB, harsh language?.


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## PAT303 (Sep 16, 2020)

GrauGeist said:


> The 7x57 passed through it like it was cardboard...



I shoot cast bullets in my .303's, they go through 1/4'' steel plate at 50m easily.

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## PAT303 (Sep 16, 2020)

Peter Gunn said:


> In it there are several shots of LW bomber parts being hauled off for scrap with quite a few bullet holes in them. I'll scan it and post it if I remember, but the gist of it is this, you can clearly see in the photos which _holes_ were made by the 20mm and which _dents_ and paint scrapings were made by the .303's.



Why would 109's shoot down their own bombers?.

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## PAT303 (Sep 16, 2020)

Shortround6 said:


> Ah, the wondrous American .50 cal
> 
> late war .50 about 800rpm with 43 gram bullet holding about 1 gram of incendiary material
> 20mm gun about 600rpm with 130 gram projectile holding 10 or more grams of incendiary or HE.
> ...



What I will say is the Mk7 .303 round is actually a hunting bullet designed by Holland and Holland, it was designed to tumble after impact. If you look at the fin as an example the larger holes could very easily have been made by a Mk7 that tumbled after penetrating from the opposite side, only trouble I have is the alloy should be folded outwards, as the for right horizontal stabiliser, those long gashes are identical to the the ones I got when shooting into the bonnet of an old car wreck we had on the farm, bullets can and do make interesting holes in objects.

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## nuuumannn (Sep 16, 2020)

MIflyer said:


> When the RAF needed some ECM aircraft they knew just where to go; they used B-24's and B-17's.



And Boulton Paul Defiants and Avro Lancasters, de Havilland Mosquitoes, Vickers Wellingtons, Handley Page Halifaxes...


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## MIflyer (Sep 16, 2020)

The jammers of 100 Group that flew missions over hostile territory were almost all B-24's and B-17's

Reference: "Confound and Destroy 100 Group and the bomber Support Campaign"

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## MIflyer (Sep 16, 2020)

When F4U's with four 20MM guns were deployed to Okinawa in 1945, they found the guns would jam at high altitudes. The reason given was that the high altitude tests had been skipped, presumably to rush them into combat.. On the other hand, I am not aware of common problems with the P-38 20MM, although the four 20MM nose installation in the A-20 was phased out early due to gun problems.

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## P-39 Expert (Sep 16, 2020)

Shortround6 said:


> View attachment 595129
> 
> 
> .Used in the F4U-5 postwar


This is a two stage engine, right? Dual sidewinder first stage and internal second stage.


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## P-39 Expert (Sep 16, 2020)

Shortround6 said:


> It was less reliable than the British version (Licence built) to start with as the British had modified theirs due to test results. Americans started with looser tolerances in general and a chamber about 1mm longer (?). The longer chamber allowed the cartridge to move forward when hit by the firing pin, this lead to a light primer strike and misfires. The Americans finally did get it straightened out but it took far to long. The Hispano was also sensitive to mounting, after all, it was designed to be bolted to a roughly 1000lb engine. The P-38s seem to have done OK, in part due the gun being mounted in a rather heavy cradle. Many of the wing guns (or even belly pack guns) did not get this heavy cradle.
> 
> In the US there was quite a bit of finger pointing as the gun makers blamed the ammunition makers and the ammunition makers blamed the gun makers.
> 
> ...


Always wondered why the P-39 stayed with the 37mm cannon, standardization would have indicated use of the 20mm. P-39 only carried 60 rounds which wasn't enough, bigger ammunition tray needed for 120-150 rounds.


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## michaelmaltby (Sep 16, 2020)

".... Always wondered why the P-39 stayed with the 37mm cannon,"
Made by Oldsmobile. IIRC. Buy American ?


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## tomo pauk (Sep 16, 2020)

PAT303 said:


> So if the .30's aren't good enough what shot down the 3,000 or so aircraft lost in the BoB, harsh language?.



3000 shot down in BoB by whom?


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## MIflyer (Sep 16, 2020)

The Flying Cannon was a big sales point for the P-39. Recall that Bell's first foray into fighters was the YFM-1, which had two 37MM guns. Consider how big a bomber would have to be fly all the way from Europe or Asia and hit the US mainland. How long would you have to shoot at a B-29 with nothing but .50 and .30 cal before it took notice of the insolent fly that was attacking it? Even in WWI there were those that said the rifle caliber machine gun was too small. A model of the SPAD was fitted with a 37MM gun firing through the prop shaft, hand loaded by the pilot; the biggest drawback was that the fumes nearly asphyxiated him.

Being able to carry a 37MM was a major selling point for the P-39 and despite its limited success they put it in the P-63, put it in the P-38D, and had plans to install it in the A-26 and A-41.

None of this AAAAAAAAH stuff! A P-39 would be Deadeye Dick, one shot one kill, no matter how big the enemy bomber was. The Soviets kept up with the idea after the war and put a 37MM in the Mig-15. 

Even Curtiss thought it was a good idea.

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## P-39 Expert (Sep 16, 2020)

MIflyer said:


> The Flying Cannon was a big sales point for the P-39. Recall that Bell's first foray into fighters was the YFM-1, which had two 37MM guns. Consider how big a bomber would have to be fly all the way from Europe or Asia and hit the US mainland. How long would you have to shoot at a B-29 with nothing but .50 and .30 cal before it took notice of the insolent fly that was attacking it? Even in WWI there were those that said the rifle caliber machine gun was too small. A model of the SPAD was fitted with a 37MM gun firing through the prop shaft, hand loaded by the pilot; the biggest drawback was that the fumes nearly asphyxiated him.
> 
> Being able to carry a 37MM was a major selling point for the P-39 and despite its limited success they put it in the P-63, put it in the P-38D, and had plans to install it in the A-26 and A-41.
> 
> ...


Agree. A 20mm with 120 rounds would have saved about 80lbs of weight and standardized the guns, but there's no arguing with the 37mm's power. The .30cal wing MGs were certainly not needed with a 37mm cannon and twin .50cal MGs all in the nose. The resultant lighter P-39 would have outclimbed the Zero in '42 erasing the only real disadvantage of climb/ceiling.

Trajectory was relatively flat out to 400 yards which was about the outer limit of accuracy with any airborne gun. It was estimated that 60-80% of pilots shot down in WWII were unaware of their assailants so the relatively slow rate of fire would have only mattered in a maneuvering fight. If you were aware of your opponent you could normally escape fighter vs fighter combat unless you had a severe performance disadvantage. 

37mm was great for ground attack also. After the jamming problem was solved in mid -'42 it became a great weapon. Russians said it was more reliable than the 20mm.

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## MIflyer (Sep 16, 2020)

Even if the guy does not know you are there, unless it is a zero deflection up the kazoo shot, judging angles will be a significant challenge. Even at only 300 mph, in one sec you move 440 ft, during which time you have managed to fire a mere two 37MM rounds, only four rounds in 880 ft. It will be all impossible to correct your fire against airborne targets. I suppose that if you charge up to a bomber formation and let fly with everything you've got you might hit something.

It's too bad we did not have fast firing 15MM cannon like the Germans did in the 109F, or that we never finished developing the .60 caliber machine gun.

I have read of but a few cases of a P-39 hitting anything with the 37MM. below is one:


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## P-39 Expert (Sep 16, 2020)

MIflyer said:


> Even if the guy does not know you are there, unless it is a zero deflection up the kazoo shot, judging angles will be a significant challenge. Even at only 300 mph, in one sec you move 440 ft, during which time you have managed to fire a mere two 37MM rounds, only four rounds in 880 ft. It will be all impossible to correct your fire against airborne targets. I suppose that if you charge up to a bomber formation and let fly with everything you've got you might hit something.
> 
> It's too bad we did not have fast firing 15MM cannon like the Germans did in the 109F, or that we never finished developing the .60 caliber machine gun.
> 
> ...


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## P-39 Expert (Sep 16, 2020)

Russians would disagree with you. They viewed it as an optimal air to air weapon. They deleted the wing guns so they must have liked it. Remember there were also twin .50cal MGs in the nose. Fired 140 rounds/minute, closer to 5 rounds in two seconds. 2.14 seconds exactly. How was it impossible to correct your fire? Each shell was a tracer so you certainly could correct your aim. Also your calculations assume your target is standing still instead of moving in roughly the same direction as you.

Was the ultimate bomber destroyer.


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## PAT303 (Sep 16, 2020)

tomo pauk said:


> 3000 shot down in BoB by whom?



More aircraft were shot down with LMG's in the BoB than anything else, over 40% of 109's were E -1/2's armed with four LMG's and considering that the 20mm ammunition on the E-4's was good for only about 9 sec's they did a lot of work with only two LMG's.


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## Greg Boeser (Sep 16, 2020)

MIflyer said:


> Even if the guy does not know you are there, unless it is a zero deflection up the kazoo shot, judging angles will be a significant challenge. Even at only 300 mph, in one sec you move 440 ft, during which time you have managed to fire a mere two 37MM rounds, only four rounds in 880 ft. It will be all impossible to correct your fire against airborne targets. I suppose that if you charge up to a bomber formation and let fly with everything you've got you might hit something.
> 
> It's too bad we did not have fast firing 15MM cannon like the Germans did in the 109F, or that we never finished developing the .60 caliber machine gun.
> 
> ...


An eyewitness to Major Miller's demise reported that he appeared dead or unconscious as the plane flew in a gradual descending turn. The plane plunged into the water and was gone.
Source: _The Aleutian Warriors, Volume I_, John Haile Cloe


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## wuzak (Sep 16, 2020)

P-39 Expert said:


> Trajectory was relatively flat out to 400 yards which was about the outer limit of accuracy with any airborne gun. It was estimated that 60-80% of pilots shot down in WWII were unaware of their assailants so the relatively slow rate of fire would have only mattered in a maneuvering fight. If you were aware of your opponent you could normally escape fighter vs fighter combat unless you had a severe performance disadvantage.



That'd be why Vultee had to come up with an elevating mechanism that allowed the two 37mm to hit the same target as the two 0.50", as well as a new sighting system, when building the XP-54.

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## P-39 Expert (Sep 22, 2020)

wuzak said:


> That'd be why Vultee had to come up with an elevating mechanism that allowed the two 37mm to hit the same target as the two 0.50", as well as a new sighting system, when building the XP-54.


Always liked the rear engine/propeller concept, thought it should have been developed earlier and further.


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## Shortround6 (Sep 22, 2020)

MIflyer said:


> It's too bad we did not have fast firing 15MM cannon like the Germans did in the 109F, or that we never finished developing the .60 caliber machine gun.



Trouble is that the German gun weighed almost exacty what the MG 151/20 and while easier to hit with each shell was much less destructive.

Same goes for the US .60 cal round. You needed a 20mm sized gun to fire it. 







.60 cal round on the right next to the standard .50 cal.


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## spicmart (May 10, 2021)

What if the P-39 had been given a competitive engine? Aerodynamically it was better than most other fighters.


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## Glider (May 10, 2021)

MIflyer said:


> The jammers of 100 Group that flew missions over hostile territory were almost all B-24's and B-17's
> 
> Reference: "Confound and Destroy 100 Group and the bomber Support Campaign"



Its Wiki but I see no reason to doubt the detail. B17's and B24's were heavily outnumbered by the other types

*Order of battle[edit]*




An electronic warfare Fortress III of 214 Squadron with nose-mounted H2S radome
No. 100 Group was headquartered at Bylaugh Hall, Norfolk from January 1944, a central location from which to administer the group's airfields in north Norfolk. No 100 Group operated from eight airfields with approximately 260 aircraft, 140 of which were various marks of Mosquito night fighter intruders with the remainder consisting of Handley Page Halifaxes, Short Stirlings, Vickers Wellingtons, Fortresses and Liberators carrying electronic jamming equipment. The group also operated the Bristol Beaufighter for a short time.
The group disbanded on 17 December 1945. During its existence it had one commander, Air Vice-Marshal Edward Addison.
100 (Special Duties) Group order of battle[4]
*SquadronAircraftFirst 100 Group operationBase*
192Mosquito II, B.IV, B.XVI, Wellington B.III, Halifax IV December 1943RAF Foulsham
141Beaufighter VI, Mosquito II, VI, XXX December 1943RAF West Raynham
239Mosquito II, VI, XXX20 January 1944 RAF West Raynham
515Mosquito II, VI3 March 1944 RAF Little Snoring, RAF Great Massingham
169Mosquito II, VI, XIX20 January 1944 RAF Little Snoring
214Fortress II, III20/21 April 1944 RAF Sculthorpe, RAF Oulton
199Stirling B.III, Halifax B.III1 May 1944 RAF North Creake
157Mosquito XIX, XXXMay 1944 RAF Swannington
85Mosquito XII, XVII5/6 June 1944 RAF Swannington
23Mosquito VI5/6 July 1944 RAF Little Snoring
223Liberator VI, Fortress II, IIISeptember 1944 RAF Oulton
71Stirling II, Halifax III15 September 1944 RAF North Creake
462 (RAAF)Halifax III13 March 1945 RAF Foulsham


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## tomo pauk (May 10, 2021)

spicmart said:


> What if the P-39 had been given a competitive engine? Aerodynamically it was better than most other fighters.



Performance-wise it would've been an excellent fighter, it was inded a streamlined fighter. With okay-ish V-1710-83 it was doing 385-400 mph.
Problem was that such versions of the V-1710 were late by at least a year (Autumn of 1942 instead of Autumn of 1941), and that Allison never series produced an 1-stage supercharged V-1710 that is comparable with Merlin XX/45/47, DB-601E or the de-rated 605A, while the 2-stage V-1710 was both too late and was too long to easily fit on the P-39. The Packard Merlin required a re-design in order to be installed on the P-39.

(a 1-stage S/Ced V-1710 with, say, 11in or 12in impeller would've been very interesting for the US fighters)

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## glennasher (May 10, 2021)

^^^^^^^ The P-39 still had all the other issues that hampered it horribly, though, COG being chief amongst them, speed is a wonderful thing, but it isn't everything.


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## tomo pauk (May 10, 2021)

It is probably easier to swallow an issue or two if a fighter does 400 mph than if it does 360 mph, while still having the issues. Especially if the pilot knows what he's doing.


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## P-39 Expert (May 10, 2021)

spicmart said:


> What if the P-39 had been given a competitive engine? Aerodynamically it was better than most other fighters.


It had competitive engines. It was too heavy in the 1942 models (D/F/K/L). Easily corrected at forward airbases by simply removing some redundant or unnecessary items. The 1943 models had uprated -83/-85 engines and performance was competitive even at the heavier 1942 weight.


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## P-39 Expert (May 10, 2021)

tomo pauk said:


> Performance-wise it would've been an excellent fighter, it was inded a streamlined fighter. With okay-ish V-1710-83 it was doing 385-400 mph.
> Problem was that such versions of the V-1710 were late by at least a year (Autumn of 1942 instead of Autumn of 1941), and that Allison never series produced an 1-stage supercharged V-1710 that is comparable with Merlin XX/45/47, DB-601E or the de-rated 605A, while the 2-stage V-1710 was both too late and was too long to easily fit on the P-39. The Packard Merlin required a re-design in order to be installed on the P-39.
> 
> (a 1-stage S/Ced V-1710 with, say, 11in or 12in impeller would've been very interesting for the US fighters)


Agree with most of what you say. V-1710 was competitive with contemporary DB (and BMW) engines when weight and displacement were taken into account. The 2-stage V-1710-93 wasn't that late, in production by April 1943 (same time as the first Packard two stage Merlin). And it did fit into a standard P-39 with minor modifications. Engine compartment was the same size as the P-63 which used the V-1710-93.


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## tomo pauk (May 10, 2021)

P-39 Expert said:


> It had competitive engines. It was too heavy in the 1942 models (D/F/K/L). Easily corrected at forward airbases by simply removing some redundant or unnecessary items. The 1943 models had uprated -83/-85 engines and performance was competitive even at the heavier 1942 weight.



Pray tell, what were those competitive engines on the P-39? The very second one suggests removing stuff from aircraft = engines were not competitive.



P-39 Expert said:


> Agree with most of what you say. V-1710 was competitive with contemporary DB (and BMW) engines when weight and displacement were taken into account.



Weight and size are concerns, unless the power and reliability justify the price of the weight and/or size size. The DB 601/605 engines' weight and size was comparable with 1-stage V-1710.
Displacement is of no concern for either designer of an aircraft, nor it is for the end user. What mattered was power at desired altitude vs. weight and size penalty, and here it took 2-stage V-1710 to match or beat the engines Germans have had in wide scale use in 1942.



P-39 Expert said:


> The 2-stage V-1710-93 wasn't that late, in production by April 1943 (same time as the first Packard two stage Merlin). And it did fit into a standard P-39 with minor modifications. Engine compartment was the same size as the P-63 which used the V-1710-93.



When one posts a picture of a real P-39 (not the all-new P-39E) with a 2-stage V-1710 installed, I'll buy the story.
What was late when mattered was, at least, the V-1710 with the 'faster' turning impeller (9.6:1 drive ratio vs. 8.8:1).


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## P-39 Expert (May 10, 2021)

tomo pauk said:


> Pray tell, what were those competitive engines on the P-39? The very second one suggests removing stuff from aircraft = engines were not competitive. *Removing unnecessary/redundant weight from an airplane will improve performance on the same engine power.*
> 
> 
> Weight and size are concerns, unless the power and reliability justify the price of the weight and/or size size. The DB 601/605 engines' weight and size was comparable with 1-stage V-1710. *V-1710 had only 79% displacement of a DB605 and 82% of a DB601. Comparable? No replacement for displacement. *
> ...


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## Glider (May 10, 2021)

P-39 Expert said:


> It had competitive engines. It was too heavy in the 1942 models (D/F/K/L). Easily corrected at forward airbases by simply removing some redundant or unnecessary items. The 1943 models had uprated -83/-85 engines and performance was competitive even at the heavier 1942 weight.



Have you ever heard of Jackanory?


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## P-39 Expert (May 10, 2021)

Glider said:


> Have you ever heard of Jackanory?


No.


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## Glider (May 10, 2021)

Look it up


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## GrauGeist (May 10, 2021)

tomo pauk said:


> The very second one suggests removing stuff from aircraft...


Yep, it's quite simple really.
Here's how to get the P-39 up to 435mph:
Eliminate the 37mm cannon, eliminate the .50MGs, eliminate all the armor (especially the nose armor), eliminate the V-1710.
Now that it's suitably lightened, tow it behind a P-59 until you've cleared the coast-line and then cut it loose

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## P-39 Expert (May 10, 2021)

Glider said:


> Look it up


I did.


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## FLYBOYJ (May 10, 2021)

GrauGeist said:


> Yep, it's quite simple really.
> Here's how to get the P-39 up to 435mph:
> Eliminate the 37mm cannon, eliminate the .50MGs, eliminate all the armor (especially the nose armor), eliminate the V-1710.
> Now that it's suitably lightened, tow it behind a P-59 until you've cleared the coast-line and then cut it loose


And put it into a dive...


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## Greg Boeser (May 10, 2021)

Then bail out.

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## tomo pauk (May 11, 2021)

P-39 Expert said:


> Removing unnecessary/redundant weight from an airplane will improve performance on the same engine power.



It was done other way around - up-engine the existing aircraft type (whether by introducing a brand new engine type, or the engine type better than what was previously used), while 'upgrading' the fuel tankage or/and firepower, so it can do things the previous version was incapable for. It was done with P-38, P-51 and, finally, with P-47 (not in the same time). It was done (if belatedly) with Spitfire and Tempest.
A P-39 that lost 500 lbs of stuff you deem redundant is still not an answer to what USAF needs in 1943 - a fighter that can do at least 400 mph and climb well at 25000 ft while having 500+ mile combat radius (preferably 650 miles) while cruising at 300+ mph TAS. Even the P-51A was incapable of that with wing racks on.



> V-1710 had only 79% displacement of a DB605 and 82% of a DB601. Comparable? No replacement for displacement.



Yes, comparable in size and weight - just as I've wrote above.
Seems like nobody said to the people at RR that they are not supposed to beat the 33.5 L DB 601 and 35L DB 605 with the 27L Merlin. Either they were wrong, or you are wrong with the displacement idea.



> Two stage -93 had a critical altitude of 21500', simply move the carb from the auxiliary stage to the engine stage (like P-38 and P-47) and increase critical altitude another 3000'. DB601 critical altitude was 18000'.



The DB-601 critical altitude was at 13-14 kft, at least for the 601A.
Critical altitude says nothing about the engine capabilities. Merlin XX, DB 605A and BMW 801D all have had critical altitude of 18700 ft, power delivered there was very different. At 22000 ft, the V-1710 E11 (P-63A fighter) was making the same power as the DB 605A.



> P-39E was not all new. Just a P-39D fuselage with the coolant tank reshaped and moved up right behind the pilot and the auxiliary stage installed in it's place. Fuselage was longer because tail cone was lengthened, but engine compartment where the auxiliary stage was located was the same size/length. Posted P-39/P-63 drawings many times, engine compartments are the same size. P-63 had the auxiliary stage, P-39 did not.



I know that P-63 have had the auxiliary stage, P-39 did not. Once someone plops the 2-stage V-1710 on a P-39 and have it flying, I'll believe.


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## drgondog (May 11, 2021)

SaparotRob said:


> Not a problem. I learned a lot and perhaps someone might model Captain Stephens’ P-51B. I believe he flew with the 355th.


355th FS/354th FG 9th AF

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## GregP (May 11, 2021)

The P-39 was already at aft CG, removing anything *forward *of the CG just makes it worse. There isn't anything much aft of the CG *that can be eliminated*. The *Aft cabin armor plate* is only 18.2 pounds. That ain't gonna' do much in the real world.

And a 2-stage Allison would not fit into a P-39. I've looked at it up close in personal, like inside a fuselage of a real P-39 with a tape measure, a few years back. It is NOT going to fit. If you MAKE it fit, you won't have a P-39. Might was well use a P-63, which is altogether a larger airplane into which a 2-stage Allison DOES fit and was designed so that it would..

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## buffnut453 (May 11, 2021)

How many effing threads do we need that discuss removing "unnecessary" weight from the P-39? For pity's sake, we've flogged this topic to death on at least 3 threads already. Can we please, PLEASE drop the dead donkey and/or quit flogging the dead horse?

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## Shortround6 (May 11, 2021)

tomo pauk said:


> Seems like nobody said to the people at RR that they are not supposed to beat the 33.5 L DB 601 and 35L DB 605 with the 27L Merlin. Either they were wrong, or you are wrong with the displacement idea.




Well, No replacement for displacement works rather well if.................................................................
Both engines are using the same fuel for roughly the same BMEP. 
If both engines are using about the same RPM 
If both engines are limited to a limited power transmission set up.

When cars were limited to 4-5 speed transmissions it was harder to keep the small high revving engine on it's power peak. 
With airplanes the constant speed prop keeps the engine turning within a few hundred rpm, broad band power not really needed (or think infinitely variable transmission between two limits) Power is changed by the throttle controlling the amount of air the supercharger is forcing into the engine. 
Limit on the air going into the engine was the capacity of the supercharger, the ability of the fuel in use to avoid detonation. The ability of the cooling system to keep the temperature in limits. and finally the strength of the engine, nothing bends or breaks after several minutes at high power.

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## wlewisiii (May 12, 2021)

If they had axed the P-39 and ordered the XP-51 right away, could Bell have also built more P-40's for Curtis? Not that it didn't have it's own quirks and flaws, but it was still a far better aircraft than the P-39 especially when flown with significant overboost.

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## Ovod (May 12, 2021)

drgondog said:


> Excellent relative to ? A6M, Bf 109F/G, Fw 190A, P-40, P-51, Spitfire V, VIII, IX or I-16 and Buffalo? As noted earlier the XP-39 was AWFUL and program nearly cancelled until NACA made bout a dozen critical cooling and aerodynamic changes to bring it to 'functional'.



How does the P-39 compare to the successful P-40? I always thought the P-39 was the more aerodynamically refined aircraft, a faster aircraft to the Curtiss in a straight line - what about climb and dive rate? I believe the P-40 had a better range and bomb load though?



> Exactly one US pilot scored 5 victory credits in the P-39 in a target rich environment in SWP.



And yet on the Eastern Front the Soviets had numerous aces who flew on the Airacobra.


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## Ovod (May 12, 2021)

SaparotRob said:


> The Soviets operated their P-39's close to the front *and mostly for ground support.*



I don't think that was true. Soviets appreciated the P-39's air-to-air qualities and mainly used it for air defence and escort duties.

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## Marcel (May 12, 2021)

Oh god, not another groundhog thread

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## drgondog (May 12, 2021)

Ovod said:


> How does the P-39 compare to the successful P-40? I always thought the P-39 was the more aerodynamically refined aircraft, a faster aircraft to the Curtiss in a straight line - what about climb and dive rate? I believe the P-40 had a better range and bomb load though?
> 
> *I would not say that the P-39 was 'excellent when compared to the P-40'. The P-39 in its variations was slightly faster and climbed slightly faster and dived slightly slower - in other words marginal in performance advantage but not 'excellent' in comparison. Range was very different for full internal combat loading with significant advantage as well as external load advantage going to P-40. There was no theatre that US contested in which Range was not a key performance attribute.*
> 
> And yet on the Eastern Front the Soviets had numerous aces who flew on the Airacobra.



The USSR liked the aircraft very much - primarily because it was a better fighter in quantity versus LW than existing operational Soviet fighters. As a weapons system it was far superior. That said the Yak 3 and LaaG 7 quickly replaced them as better front line fighters.

Additionally it should be noted that USSR air fighting doctrine for low to middle altitudes, and the fact that the P-39 was not required to contest the LW at high altitudes put the P-39 in its most favorable envelope. The early P-51 was 'excellent' in comparison to both the P-40 and P-39

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## P-39 Expert (May 12, 2021)

Ovod said:


> How does the P-39 compare to the successful P-40? I always thought the P-39 was the more aerodynamically refined aircraft, a faster aircraft to the Curtiss in a straight line - what about climb and dive rate? I believe the P-40 had a better range and bomb load though?
> 
> 
> 
> And yet on the Eastern Front the Soviets had numerous aces who flew on the Airacobra.


P-39 was faster than every contemporary P-40 and was far superior in climb/ceiling. Range/endurance was about the same. P-40's extra 30 gallons of fuel was eaten up by a higher takeoff/climb allowance and lower cruising speed at the same power settings.


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## P-39 Expert (May 12, 2021)

drgondog said:


> The USSR liked the aircraft very much - primarily because it was a better fighter in quantity versus LW than existing operational Soviet fighters. As a weapons system it was far superior. That said the Yak 3 and LaaG 7 quickly replaced them as better front line fighters. *Lend-lease P-39N/Q began arriving in Russia in spring '43. Yak-3 didn't get into combat until summer '44 and Lagg-7 until fall '44. Their performance figures were no better than the P-39.*
> 
> Additionally it should be noted that USSR air fighting doctrine for low to middle altitudes, and the fact that the P-39 was not required to contest the LW at high altitudes put the P-39 in its most favorable envelope. The early P-51 was 'excellent' in comparison to both the P-40 and P-39. *The P-39 had to fight the LW at whatever altitude they chose. P-39 had comparable performance to contemporary LW fighters at all altitudes. Early P-51 meaning Allison P-51? Slightly faster (10-20mph) but not as good climb or ceiling. Allison P-51 grossed 8600lbs, P-39N/Q grossed about 7150lbs after the Russians deleted the wing guns and IFF radio. Kept the voice radio. *


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## swampyankee (May 12, 2021)

Denniss said:


> P-39 is somewhat strange, most western allied nations disliked them but the soviets loved them.



Oddly, the USAAF managed to specify and Bell to design an aircraft that didn't suit any missions the US had for it, but it was perfect for the Soviets. I don't know quite how they managed this.

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## P-39 Expert (May 12, 2021)

tomo pauk said:


> It was done other way around - up-engine the existing aircraft type (whether by introducing a brand new engine type, or the engine type better than what was previously used), while 'upgrading' the fuel tankage or/and firepower, so it can do things the previous version was incapable for. It was done with P-38, P-51 and, finally, with P-47 (not in the same time). It was done (if belatedly) with Spitfire and Tempest. *The 1942 P-39 (D/F/K/L) was way too heavy when compared with contemporary fighters power/weight ratio. Delete the unnecessary/redundant wing guns, nose armor plate and IFF radio and those P-39s weigh 7150lbs. *
> A P-39 that lost 500 lbs of stuff you deem redundant is still not an answer to what USAF needs in 1943 - a fighter that can do at least 400 mph and climb well at 25000 ft while having 500+ mile combat radius (preferably 650 miles) while cruising at 300+ mph TAS. Even the P-51A was incapable of that with wing racks on. *No plane will meet these specs until the Merlin P-51 in 1944. A 1943 P-39N was very competitive with any other 1943 fighter. Except the early two stage Spitfire MkIX. *
> 
> 
> ...


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## buffnut453 (May 12, 2021)



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## pbehn (May 12, 2021)

buffnut453 said:


> View attachment 622970


On doctors advice, I am no longer allowed to install or remove fuel tanks, armour or weapons, at any time.

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## DerAdlerIstGelandet (May 12, 2021)

Marcel said:


> Oh god, not another groundhog thread



Excuse me while I go bang my head against the wall.

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## buffnut453 (May 12, 2021)



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## wuzak (May 12, 2021)

P-39 Expert said:


> *A 1943 P-39N was very competitive with any other 1943 fighter. Except the early two stage Spitfire MkIX.*



The "early 2 stage Spitfire MkIX" was a 1942 aircraft.

By 1943 the engines had improved.

Do you think the P-39N is actually a match for the P-51A? The P-51A being faster and longer ranged.

What about the Spitfire XII? Sure only 100 made, but top speed about the same as the P-39N, best performance in a similar altitude band, but better climb rate than the P-39N.

Typhoon Ib? Faster, with more firepower. And range.

Fw190A (not sure which subvariant was best by 1943)? By your own reckoning, the P-39N was no match for the Spitfire IX, the Fw190A was, or was close. Surely that would mean the Fw 190A outmatched the P-39N?

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## GrauGeist (May 13, 2021)

Well, here we are once again...





_(image source: Fubar57's gallery of nessecary and practical illustrations)_

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## Snautzer01 (May 13, 2021)

Picture of a dead thread creeping back to life.

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## P-39 Expert (May 13, 2021)

wlewisiii said:


> If they had axed the P-39 and ordered the XP-51 right away, could Bell have also built more P-40's for Curtis? Not that it didn't have it's own quirks and flaws, but it was still a far better aircraft than the P-39 especially when flown with significant overboost.


No way the P-40 was superior to the P-39 in speed climb ceiling or range.


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## buffnut453 (May 13, 2021)

P-39 Expert said:


> No way the P-40 was superior to the P-39 in speed climb ceiling or range.



P-40E Range: 716 mi (1,152 km, 622 nmi) at 70% power
P-39Q Range: 525 mi (845 km, 456 nmi) on internal fuel 

Is this some kind of new math where 525 is actually greater than 716?

Of course the P-39's range can be increased by the addition of the external drop tank...but that reduces its speed to below that of the P-40.

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## P-39 Expert (May 13, 2021)

wuzak said:


> The "early 2 stage Spitfire MkIX" was a 1942 aircraft. *Only 4 squadrons active with the Mk IX before Sept '42, basically test batches. Real production of the Mk IX was in 1943.*
> 
> By 1943 the engines had improved.
> 
> ...


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## tomo pauk (May 13, 2021)

P-39 Expert said:


> The 1942 P-39 (D/F/K/L) was way too heavy when compared with contemporary fighters power/weight ratio. Delete the unnecessary/redundant wing guns, nose armor plate and IFF radio and those P-39s weigh 7150lbs.



Still does not do things required by USAAF Pacific (the area USAAF was mostly fighting in 1942). In best part of 1942, it required the -83 engine (so it can compete above 15000 ft) and at least 50% more fuel (so it can cover the area better). 
It wasn't so.



> No plane will meet these specs until the Merlin P-51 in 1944. A 1943 P-39N was very competitive with any other 1943 fighter. Except the early two stage Spitfire MkIX.



P-47 has certainly a potential to do 500 mile escort with wing tanks in 1943. P-38 - ditto (and a bit longer). P-39 can do how much of the escort job at 25000 @ 300 mph TAS? 250-300 miles?



> I'm wrong that a 20% larger engine should make more power?
> Yes, with 20% less displacement.



You've answered your own question there.



> Never said any P-39 had the two stage engine (except the P-39E), just said it would fit with minor modifications. The engine was in production in April '43 but the first P-63 airframe wasn't ready until October '43. Put the engine in the P-39 until the P-63 was ready.



P-39E required major modifications of central and rear fuselage in order to the cooling systems and the 2-stage engine to fit inside. Once all of that was done, the P-39E was found to have dangerous spin characteristics - no wonder with the extra weight added aft the CoG.


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## Schweik (May 13, 2021)

GregP said:


> The P-40 used a similar engine that was rated mostly at about 1,325 hp. Some had engines of 1,425 HP or so. Two variants of the P-40, the P-40F and P-40L, had Packard-Merlin V-1650 engine, but the Merlins so used were single-stage engines and the resulting P-40s performed almost the same as with the Allison engines. The Merlin-powered units were very slightly faster and had very slightly better altitude performance, but not enough to make much of a difference. They were still low-altitude fighters. You can tell the Merlin units because they airscoop on top of the nose is missing.



Good post overall, but this part is incorrect and it's one of those tropes that just lingers forever.

The *Merlin engine did make a big difference*, big enough that the Merlin engined variants were almost the only type of P-40 used by the five American fighter groups that flew P-40s in the Mediterranean Theater (North Africa and then Italy). The Merlin engine, being single-stage (but two speed), didn't do for the P-40 what the (2 stage) Merlin did for the P-51, and it didn't turn it into a high altitude fighter, but it _did_ increase the combat altitude considerably and that was the main reason it was so much in demand. 

P-40 variants in the MTO included:

P-40 B/C (Allison Engined used only by the British and Commonwealth Air Forces as Tomahawk IIA and IIB)
P-40 D/E (Allison V-1710-39, used only by the British and Commonwealth Air Forces as Kittyhawk I and IA)
P-40 F (Merlin 28 / V-1650-1 engined, used by 5 US fighter groups, 2 British squadrons as Kittyhawk II, and 1 Free French)
P-40 L (Merlin 28 / V-1650-1 engined, used by 5 US fighter groups, 2 British squadrons, as Kittyhawk IIa, and 1 Free French)
P-40 K (Allison V-1710-73, used briefly by one US FG - 57th FG - during a shortage of Merlin engines, used by British and Commonwealth units as Kittyhawk III)
P-40 M (Allison V-1710 -81 used by British and Commonwealth forces as Kittyhawk III, mainly used as a fighter bomber)
P-40 N (Allison V-1710 -115 and others, used by British and Commonwealth forces as Kittyhawk IV, almost exclusively used as a fighter-bomber)

All variants through the K were used in the air superiority role, but only the F/L could be called successful in terms of win / loss ratios. The P-40B/C "Tomahawk" had an effective performance ceiling of about 14,000 ft and could fight up to about 16-17,000'. The E and K had an even lower effective performance ceiling of about 12,000' . Above about 15,000 they were very sluggish. The K was considered one of the best Allison variants however because the allowed boost settings had been increased, and at WEP setting it had 1,550 hp available, but only down below 3,000 ft. The M and N varied but most had a higher-tuned engine with an effective ceiling of around 17-18,000', but with lower maximum boost allowed down low.

The critical altitude for the (Packard Merlin) V-1650 powered P-40F and L was just under 18,000 ft, and they were able to operate effectively up to a bit over 21,000. This wasn't much lower than the effective performance altitude for the Spitfire Mk V, and it made a significant difference. At altitude it was about 30 mph faster than a P-40E and (depending on the loadout) had a much improved rate of climb. They were able to operate 6-8,000' higher than the Allison P-40 models which meant being pounced less often and with less ease by Bf 109s and MC 202s.

It's worth noting that the P-40N was widely used by the USAAF in the Air Superiority role in the Pacific and China / India / Burma Theaters against Japanese fighters, but was not considered viable for operations against the Germans, whereas the Merlin powered F and L were. 

The P-39 was used briefly by US forces in the Med, but after some disastrous engagements was relegated to 'Coastal Patrol' duties, for which it was ill suited due to short range. After a gradual familiarization process and some improved models with more powerful engines arrived in Theater, it was put into use as a fighter bomber in Italy with moderate success. 

There were 18 US pilots who made Ace while flying P-40s in the MTO, and at least 35 British and Commonwealth pilots, but so far as I've been able to determine only one US P-39 Ace in the entire war, and that was in the Pacific. 

US P-40 pilots claims: 592 victories in the MTO, 660.5 in the PTO, and 973 in China for a total of 2225.5
US P-39 pilots claims: 2.5 victories in the ETO, 25 in the MTO, 288 in the Pacific, 5 in China, for a total of 320.5

The Russians were able to do something with the P-39 that neither the US nor the British nor the other Western Allies we saddled with them (some high scoring Italian and French aces were killed in accidents in these planes) were able to do.

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## Peter Gunn (May 13, 2021)

pbehn said:


> On doctors advice, I am no longer allowed to install or remove fuel tanks, armour or weapons, at any time.


My doctors advice is I am no longer allowed to partake in any discussion regarding the P-39.

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## pbehn (May 13, 2021)

Peter Gunn said:


> My doctors advice is I am no longer allowed to partake in any discussion regarding the P-39.


I got the same but from my anger management consultant, and mental health awareness self help group.

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## P-39 Expert (May 13, 2021)

buffnut453 said:


> P-40E Range: 716 mi (1,152 km, 622 nmi) at 70% power
> P-39Q Range: 525 mi (845 km, 456 nmi) on internal fuel
> 
> Is this some kind of new math where 525 is actually greater than 716?
> ...


According the the pilot's handbooks for P-40E and P-39K/L (same engine power above 12000ft):

Clean:
P-40 12000ft 148gal less 28gal warmup&climb = 120net gallons divided by 41gph = 2.9hours x 235mph = 681mi. 
P-39 12000ft 120gal less 20gal warmup&climb = 100net gallons divided by 33gph = 3.0hours x 241mph = 723mi. P-39 cruised faster than P-40 at a lower power setting.

We can do this at any altitude with any external tank. P-39 was faster, climbed faster and cruised farther then P-40.


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## Thumpalumpacus (May 13, 2021)

Peter Gunn said:


> My doctors advice is I am no longer allowed to partake in any discussion regarding the P-39.



Huffing the dirt from a groundhog discussion impairs respiration, I'm told.

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## Milosh (May 13, 2021)

Flight Operation Instruction Chart

P39FOIC.pdf (zenoswarbirdvideos.com) 
P-40FOIC.pdf (zenoswarbirdvideos.com)


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## P-39 Expert (May 13, 2021)

tomo pauk said:


> Still does not do things required by USAAF Pacific (the area USAAF was mostly fighting in 1942). In best part of 1942, it required the -83 engine (so it can compete above 15000 ft) and at least 50% more fuel (so it can cover the area better).
> It wasn't so. *In 1942 the AAF was in a defensive position. Only thing the P-39 had trouble doing was intercepting IJN bombers at 18000-22000ft headed for Moresby. Could intercept them about half the time. At 7150lbs it could intercept them all the time. Otherwise the escort of medium bombers and transports was no problem.*
> 
> 
> ...


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## P-39 Expert (May 13, 2021)

Milosh said:


> Flight Operation Instruction Chart
> 
> P39FOIC.pdf (zenoswarbirdvideos.com)
> P-40FOIC.pdf (zenoswarbirdvideos.com)


I used that same P-40D/E chart for my calculations.
That P-39 chart is for a P-39Q with 86 gallons internal and a different engine. I used a P-39K/L chart with a more comparable engine and the normal 120gal internal fuel.


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## Milosh (May 13, 2021)

Produce the chart.


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## drgondog (May 13, 2021)

P-39 Expert said:


> According the the pilot's handbooks for P-40E and P-39K/L (same engine power above 12000ft):
> 
> Clean:
> P-40 12000ft 148gal less 28gal warmup&climb = 120net gallons divided by 41gph = 2.9hours x 235mph = 681mi.
> ...


 Nope - P-39 Faster (under 18K vs P-40F, then P-40F faster by 20mph), better acceleration (under 18K vs P-40F/K) and better climber (except vs P-40F/K from 18K ), much slower roll rate than P-40 (any model), less terminal dive speed, shorter range, less external load, less practical armament than P-40E and Subs, for most strafing and all air to air due to the issues with M-4 37mm cannon. Nobody in USAAF, RAF, Commonwealth, French and Italians were crying for more P-39s.

Don't depend on your calculations -use USAAF Published Tables as reproduced on page 599 of AOHT, Table 100. Boundary conditions are 10 minutes of fuel for warm up, taxi, takeoff and landing. It allows for fuel used to climb to 10,000 feet, cruise and 10% of net ideal range for other factors - at more economical power speed. Below table values are for pure straight line range from take off to reserve point..

Pilot Handbook values were contractor developed and the USAAF tables were developed from flight testing - and averaged across multiple ships same type.

P-39D/F/K (VERY best P-39 range performance w/120 gal and TO weight of 7650) = 600 mi. The P-39N w/87gal TO wt of 7550 =350 mi; =550mi for 120gal.
The P-39N is probably the best comparison as it was most widely produced
P-40E (149gal and TO weight of 8700) = 650mi
P-40F/K (157gal Merlin 1650-1, TO weight of 8800) = 700mi

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## wuzak (May 13, 2021)

P-39 Expert said:


> *Only 4 squadrons active with the Mk IX before Sept '42, basically test batches. Real production of the Mk IX was in 1943.*



You mean the 4 squadrons hat took part in the Dieppe landings?

I doubt they were "test batches". Just early production machines. And production started months earlier and continued.




P-39 Expert said:


> *You said it, only 100 made. Griffon engine was 30% larger than the Allison and had a two stage supercharger. Not really any faster and didn't climb as well as a P-39N.*



The Spitfire XII was powered by either a Griffon II, Griffon III or Griffon VI, all single stage, 2 speed models. With the Griffon VI the maximum climb rate was very nearly 5,000fpm.

The reason only 100 were made was because the Griffon was needed for the Firefly, and that 2 stage Griffon Spitfire was being developed.

The 2 stage Griffon powered Spitfire was the XIV, which started production in 1943, but did not see service until 1944.

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## DerAdlerIstGelandet (May 13, 2021)

drgondog said:


> Nope - P-39 Faster (under 18K vs P-40F, then P-40F faster by 20mph), better acceleration (under 18K vs P-40F/K) and better climber (except vs P-40F/K from 18K ), much slower roll rate than P-40 (any model), less terminal dive speed, shorter range, less external load, less practical armament than P-40E and Subs, for most strafing and all air to air due to the issues with M-4 37mm cannon. Nobody in USAAF, RAF, Commonwealth, French and Italians were crying for more P-39s.
> 
> Don't depend on your calculations -use USAAF Published Tables as reproduced on page 599 of AOHT, Table 100. Boundary conditions are 10 minutes of fuel for warm up, taxi, takeoff and landing. It allows for fuel used to climb to 10,000 feet, cruise and 10% of net ideal range for other factors - at more economical power speed. Below table values are for pure straight line range from take off to reserve point..
> 
> ...



It’s futile my friend. I would not waste my time. He’s right, you’re wrong...

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## DerAdlerIstGelandet (May 13, 2021)

I have moved all the P-39 vs P-40 talk into this thread about the P-39 vs. the P-40.



 P-39 Expert
stop hijacking threads and turning them into P-39 threads. It’s getting really tiring...

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## pbehn (May 13, 2021)

wuzak said:


> You mean the 4 squadrons hat took part in the Dieppe landings?


According to wiki there were 6 squadrons of Spitfire Mk IXs at Dieppe, 4 RAF and 2 RCAF. 

"Six squadrons (four British, two Canadian) flew the Spitfire Mk IX, the only British fighter equal to the Fw 190, on its operational debut at Dieppe.[46] Copp, Terry. "The Air over Dieppe." _Legion_, June 1996, p. 8" Dieppe Raid - Wikipedia


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## buffnut453 (May 13, 2021)

DerAdlerIstGelandet said:


> I have moved all the P-39 vs P-40 talk into this thread about the P-39 vs. the P-40.
> 
> 
> 
> ...



Or, better yet, find another topic to talk about. Any topic...we're not picky.

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## glennasher (May 13, 2021)

pbehn said:


> According to wiki there were 6 squadrons of Spitfire Mk IXs at Dieppe, 4 RAF and 2 RCAF.
> 
> "Six squadrons (four British, two Canadian) flew the Spitfire Mk IX, the only British fighter equal to the Fw 190, on its operational debut at Dieppe.[46] Copp, Terry. "The Air over Dieppe." _Legion_, June 1996, p. 8" Dieppe Raid - Wikipedia





If memory serves, that was also the debut of the Allison Mustang, (in RAF service), when Hollister shot down at least one FW-190. It was a pretty big day.

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## pbehn (May 13, 2021)

glennasher said:


> If memory serves, that was also the debut of the Allison Mustang, (in RAF service), when Hollister shot down at least one FW-190. It was a pretty big day.


In all sorts of ways, those Spitfires were escorting US manned B-17s, the Mustang MkI also had its first loss. As I understand it it was the first time combat was "joined " with the Mustang Mk I, they had been on operations before that. Quote "After the arrival of the initial aircraft in the UK in October 1941, the first Mustang Mk Is entered service in January 1942, the first unit being 26 Squadron RAF. Due to poor high-altitude performance, the Mustangs were used by Army Co-operation Command, rather than Fighter Command, and were used for tactical reconnaissance and ground-attack duties. On 10 May 1942, Mustangs first flew over France, near Berck-sur-Mer. On 27 July 1942, 16 RAF Mustangs undertook their first long-range reconnaissance mission over Germany. During the amphibious Dieppe Raid on the French coast (19 August 1942), four British and Canadian Mustang squadrons, including 26 Squadron, saw action covering the assault on the ground. " from The History Hangar - Mustang I

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## Admiral Beez (May 13, 2021)

GrauGeist said:


> Except Japan. Japan didn't like the Bf109.


Some good info here..

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## FLYBOYJ (May 13, 2021)

P-39 Expert said:


> Of course unloading the wing guns* (and nose armor plate)* would have helped the N also, but it already climbed well at normal gross weight.


I think you've been shown on more than one occasion that if you remove the nose armor plate you will go outside the rear C/G limit if you use all your cannon ammo and get down to 1/4 fuel.

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## Schweik (May 13, 2021)

Admiral Beez said:


> Some good info here..




That was really interesting, thanks for posting!


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## fubar57 (May 14, 2021)

Why is the P-39 the best fighter ever?

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## GregP (May 14, 2021)

Regarding post #183 Schweik, I have the following:






Looks like the P-40F had about 10 mph on the P-40E, which isn't very much. Still, an advantage IS an advantage. The P-40F had about a 6% climb advantage. Again, not a game changer. The P-40F had about 5,400 feet ceiling advantage. That is more significant than the speed or climb, but in actual fighter performance, the P-40 E started dropping off at about 15,000 feet and the P-40F started dropping off at about 19,000 feet. So, it had a medium advantage, though the P-40E was in combat a full 5 months earlier than the P-40F.

Then we get to the P-40L and P-40N. They only entered combat two months apart, with the P-40L getting there first. The Allison-powered P-40N (interceptor version) was about 6 mph faster, climbed 880 fpm better than the P-40L, and had a 2,200 foot service ceiling advantage. The P-40N's climb was 33% better than the P-40L. The N had a very slight speed advantage, not enough to matter, and the N had about a 6% service ceiling advantage.

So, the P-40F had a slight advantage for about 2 years early in the war and the P-40N had about the same advantage for 2 years later in the war except for climb, where it had a much more significant advantage.

I'll stick with the Allison, myself, overall. In a perfect world where choice was an option, I'd have an Allison P-40 up until Dec 41, right about Pearl Harbor time. Then I'd fly a P-40F until Mar 43, at which time, I'd opt for a P-40N. I'd WISH for a P-40Q that would never show up.

The weights above are for normal combat loadout, not maximum takeoff weight.

I just do not see the P-40F as having a very significant advantage over the P-40E though it DID, in fact, have one. The P-40N DID have a pretty good climb advantage over the P-40L. All in all, they weren't all that much different from one another. Sort of "incremental improvements."

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## Schweik (May 14, 2021)

Right. But those numbers are a bit off. They are basically the 'brochure numbers'. The real top speed of the P-40E was a bit over 345 mph at about 13,000 ft. See also here. The real top speed of the P-40F was 370 mph. at 20,000 ft. Note from that same link that the P-40F is down to 347 mph at 30,000 ft, and that is because of reduced power. They did not fight at that altitude normally. And they certainly weren't operating at 34,000 ft any more than a P-40E was hunting at 29.000. The ratios are about right but the real fighting altitudes were much lower.

All of those ceilings are way, way high. Again, brochure numbers. Performance on the Allison P-40s was badly reduced at 12-16,000 ft (depending on the gear ratio of the specific Allison engine subvariant) and really did not permit safe combat operations much over 20,000. They managed to pull off some interceptions a bit over 22,000 ft over Darwin by taking a pair of guns out and removing some other stuff, and they could only make one pass at the Japanese bombers before needing to dive away before a fighter got near them. It wasn't considered safe to fight above the performance ceiling. As you can see on this chart - level speed for the P-40E is down to 330 mph at 20,000 ft. That's compared to a Bf 109F doing ~ 380 mph. Not safe. Rate of climb for a P-40E is down to 1,000 feet per minute at 20k ft at max boost, and declining rapidly.

The difference in speed is largely down to the altitude. Assuming we are talking about one of the strengthened V-1710-39s for the P-40E, speed was probably about equivalent or maybe a bit better down low for the Allison engined version. It was definitely better for the P-40K.

Those climb numbers for the F reflect overload conditions, actual numbers for the 'lightened' (and four gun) F and L are about the same as the 'lightened' (four gun) N, i.e. about 3,300 fpm initially, but the F / L get another boost to climb rate when their second gear kicks in at around 14,000 ', right when the Allison is starting to gasp. However fewer of the 'lightened' N seem to have been used, and none in the MTO as far as I've been able to determine.


As for which one would be better- for air superiority operations against the disciplined fighting style of the Germans, there is no doubt the P-40F/L was better. Against the Japanese, where a lot of fighting occurred down low for a variety of reasons, the Allison was probably better. Also for fighter-bombing operations down low in either Theater, again the Allison is better because it gives very good power below 5,000 ft.

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## P-39 Expert (May 14, 2021)

FLYBOYJ said:


> I think you've been shown on more than one occasion that if you remove the nose armor plate you will go outside the rear C/G limit if you use all your cannon ammo and get down to 1/4 fuel.
> 
> View attachment 623137


And I have stated more than once that the IFF radio in the tail cone could be moved up under the rear canopy above the engine or removed altogether for balance.


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## Milosh (May 14, 2021)

P-39 Expert said:


> And I have stated more than once that the IFF radio in the tail cone could be moved up under the rear canopy above the engine or removed altogether for balance.


Have you ever done a proper weight and balance with all the changes you make? I don't remember any being posted.


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## Admiral Beez (May 14, 2021)

Schweik said:


> That was really interesting, thanks for posting!


His channel is really interesting, especially the cockpit tours.

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## Peter Gunn (May 14, 2021)

Yeah, but most important, the P-40B was the best looking.

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## Peter Gunn (May 14, 2021)

Milosh said:


> Have you ever done a proper weight and balance with all the changes you make? I don't remember any being posted.


Now you've done it.

Much like saying "Beetlejuice..."

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## vikingBerserker (May 14, 2021)

Are we talking about the African P-39, or the European P-39?

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## Shortround6 (May 14, 2021)

Laden or unladen?

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## buffnut453 (May 14, 2021)

P-39 Expert said:


> And I have stated more than once that the IFF radio in the tail cone could be moved up under the rear canopy above the engine or removed altogether for balance.


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## tomo pauk (May 14, 2021)

P-39 Expert said:


> In 1942 the AAF was in a defensive position. Only thing the P-39 had trouble doing was intercepting IJN bombers at 18000-22000ft headed for Moresby. Could intercept them about half the time. At 7150lbs it could intercept them all the time. Otherwise the escort of medium bombers and transports was no problem.



Spitfires at Darwin didn't have it exclusively their own way in 1942, so I would not hold much of hope for P-39s doing better (or the same), even with weight reduction.
Escort of B-25s for ranges they were capable for was out of question - the B-25 _combat radius_ was almost as good as _range_ of P-39.

[/QUOTE]P-47 could only escort about 350mi radius in 1943 and then only after drop tanks introduced in August. I have a range chart but can't seem to make it attach. [/QUOTE]

Two drop tanks under the wing, as used by P-47s for ferrying in August of 1943 from USA to UK via Iceland. Or use a proper metalic flat tank of 200 gals under the belly, as used on P-47s in Pacific from August 1943.

[/QUOTE]A larger engine will make more power. 
I'm not talking about an 8900lb P-39E. I'm saying put the -93 engine in a standard P-39, offset the weight of the auxiliary stage with a larger four blade propeller. The -03 engine would fit into a standard P-39, I've shown the drawings on here many times. Whole thing would have weighed about 7900lbs. 
[/QUOTE]

NI see no point to discuss that anymore.


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## SaparotRob (May 14, 2021)

All this for the P-39 and we still haven’t found the time to make the Buffalo a world beater.

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## FLYBOYJ (May 14, 2021)

P-39 Expert said:


> And I have stated more than once that the IFF radio in the tail cone could be moved up under the rear canopy above the engine or removed altogether for balance.


1. It won't make a difference, 2. You're trying to argue about something that doesn't exist. 3. Do you have Bell engineering drawings to show this installation in any area you mention? If you don't it doesn't exist! Stop with the hypothetical BS to support your arguments, it's getting old.

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## buffnut453 (May 14, 2021)

FLYBOYJ said:


> Stop with the hypothetical BS to support your arguments, it's getting old.



Joe, you are WAAAAYYYY off base here. It GOT old about 6 months ago. By now, it's decomposing and fly-blown...but the poor animal continues to be flogged.

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## FLYBOYJ (May 14, 2021)

buffnut453 said:


> Joe, you are WAAAAYYYY off base here. It GOT old about 6 months ago. By now, it's decomposing and fly-blown...but the poor animal continues to be flogged.

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## GrauGeist (May 14, 2021)

SaparotRob said:


> All this for the P-39 and we still haven’t found the time to make the Buffalo a world beater.


It was, you just don't understand.
If you moved the cockpit, lengthened the fuselage, widened the wings, moved the two cowl .50MGs to the wings alingside the other two .50MGs, changed the radio location and upgraded the engine to an R-1830...wait, I just created an F4F.

Nevermind...

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## GregP (May 14, 2021)

Hi Schweik,

All U.S. WWII airplanes had to meet the specs ± a few percent. IIRC, the P-40 has to meet specs ±5%. That means a P-40E could be right on the 360 mph spec or could be as much as 18 mph faster or slower. You claim they were all slower. I say bunk. Some were, some weren't. Same went for the P-40F. In point of fact, I'd say most P-40E models were 350 - 360 mpg airplanes and most P-40Fs were 360 - 370 mph airplanes. A few were a small bit faster and a few were a small bit slower.

As for the P-40s I know of today, almost all I know of (5 of them personally) are faster than spec, no doubt due to having less weight (no armor or armament), having replica fake guns that are not quite as draggy as real installations, and are generally in better shape than wartime airplanes that sat outside in a dirt field all the time.

In 2017, at the Reno Races, there was a stock (take with a grain of salt) P-51D, "Little Horse," that flew the course at 267.192 mph in Bronze class. There was a P-40E, "Texas Warhawk," that flew the course at 267.527 mph in Bronze class and beat the P-51D. It surely didn't look slow, and was also not much modified, if at all. These guys were running 3,000 rpm and whatever MAP they wanted to run with stock engines, but they were not there to lose. They weren't at 25,000 feet, but instead were down low at Reno (5,050 feet MSL plus whatever density altitude was added due to temperature).

Sorry, but someone saying the "real" P-40s were slower than spec doesn't cut it. One test does not a production run of airplanes specify. According to real former AVG pilots, they used to fly them at 70" - 75" when in combat, and they weren't "slow" and bettered ALL specs at high power levels.

When I look at WWIIaircraftperformance, I see a test of a P-40E, SN 40-633, and it had a top speed of 342 mph at 11,400 feet. Best climb rate was 2,400 fpm. Note the MAP ws 43.9" MAP. When I scroll down to the P-40F test, SN 41-13635, I see a top speed of 365.5 mph with belly tank sway braces installed and 374 mph without the sway braces. At 12,800 feet, the closest I can see to the P-40E, it went 350 mph, or about 87 mph faster about 1,400 feet higher. Best climb rate was 2,210 fpm. Note, the MAP was at 48" MAP. Now, myself, I'd wonder why they didn't run the Allison at 48" MAP if they wanted an apples-to-apples comparison, but these were individual test and NOT a comparison.

The P-40E was tested 5 Apr 43 and the P-40F was tested 11 Jul 42, so the P-40E had a LOT more hours on it than the P-40F did. I'm surmising you are inferring the P-40E was a 345 mph airplane based on one test. But, the test was on a 2+ year old airplane while the P-40F test was on a much newer and I have read many reports where a P-40E did 360 mph.

All in all, seems like they weren't exactly stretching the P-40E in the test on the website. But, that particular airplane WAS20 mph slower at the power they used.

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## SaparotRob (May 14, 2021)

See? It wasn’t hard. Thanks GrauGeist.

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## Schweik (May 14, 2021)

GregP said:


> Hi Schweik,
> 
> All U.S. WWII airplanes had to meet the specs ± a few percent. IIRC, the P-40 has to meet specs ±5%. That means a P-40E could be right on the 360 mph spec or could be as much as 18 mph faster or slower. You claim they were all slower. I say bunk. Some were, some weren't. Same went for the P-40F. In point of fact, I'd say most P-40E models were 350 - 360 mpg airplanes and most P-40Fs were 360 - 370 mph airplanes. A few were a small bit faster and a few were a small bit slower.



The speed - and especially altitude performance - depends on weight and drag. The British tests were done with field conditions. For example the P-40F they clocked at 370 mph had bomb shackles on it. Bomb shackles, and other things like rearview mirror, direction finding antenna, radio mast, open gun ports etc. slow a plane down to a surprising degree. Weight has slightly less effect on speed but it does affect altitude performance... which in turn affects speed.

When the companies do the tests to validate their contract, they did everything allowed to improve the performance. This often means reduced fuel, reduced or no ammunition, and typically no external accoutrements. They also sanded and waxed the planes and even sometimes puttied over little gaps and holes. By contrast, the tests I posted links to, which are not invented or made up, they are actual WW2 evaluations, were done at full combat weight, with the usual gear used in the field, and at the boost settings recommended in the manual. One of those speed tests I posted on the P-40E was done in Australia and the other in Britain. Yet they came up with fairly identical results.



> As for the P-40s I know of today, almost all I know of (5 of them personally) are faster than spec, no doubt due to having *less weight* (no armor or armament), having replica fake guns that are *not quite as draggy* as real installations, and are generally in better shape than wartime airplanes that sat outside in a dirt field all the time.



Exactly. This is the issue. I don't think the P-40 was slow or sluggish, especially once they increased the boost settings past 45". The issue is basically a matter of altitude. As has been noted before in this thread I believe, in one of the other tests done in Australia it was noted that the P-40E was faster than the Spitfire Mk V they were testing at low to mid altitude. At say, 8,000 ft the P-40 was quite fast, at 2,000 feet using WEP or overboost, it was extremely fast for the time period. But precious few WW2 fighters were exceeding 350 mph at 2,000 feet.

The speed, in other words, is largely a function of altitude. Specifically power at altitude. The reason the P-40F was 30-40 mph faster than the P-40E was because it's engine was still generating pretty good power at higher altitude where the air is thinner. The second speed gives it a bump up above 15,000 ft.

Part of the reason the P-51 was so fast was that it was very well streamlined, and it had a bit of thrust from it's exhaust system etc., but the other (main) reason is that it had plenty of power at 30,000' where the air is a lot thinner.



> In 2017, at the Reno Races, there was a stock (take with a grain of salt) P-51D, "Little Horse," that flew the course at 267.192 mph in Bronze class. There was a P-40E, "Texas Warhawk," that flew the course at 267.527 mph in Bronze class and beat the P-51D. It surely didn't look slow, and was also not much modified, if at all. These guys were running 3,000 rpm and whatever MAP they wanted to run with stock engines, but they were not there to lose. They weren't at 25,000 feet, but instead were down low at Reno (5,050 feet MSL plus whatever density altitude was added due to temperature).



Right, and down low, I can imagine the P-40 could be competitive with the P-51, as you say depending on Manifold pressure they were willing to push the engine to. The Mustang is less draggy etc. but the Allison has plenty of power down low especially if it's in good shape and they are willing to push it a bit.



> Sorry, but someone saying the "real" P-40s were slower than spec doesn't cut it. One test does not a production run of airplanes specify. According to real former AVG pilots, they used to fly them at 70" - 75" when in combat, and they weren't "slow" and bettered ALL specs at high power levels.



Yes but you can't do 70" boost when you are up at 20,000 ft. More like 2,000 ft. I have spoken to some real AVG and other P-40 pilots in person by the way, and read plenty of their biographies and autobiographies, as I'm sure you have.

I am not a critic of the P-40. To the contrary I've been accused on this forum more than once of being a fanboy. But I try to stay within the parameters of reality. As far as I can tell the 'brochure specs' for just about_ all_ WW2 aircraft are a bit distorted. It seems like whatever was published by the War department in 1942 and then written down in some 'Fighters of the World' type book in the early 1960s by Bill Gunston or somebody just seems to be repeated over and over. This goes for positive and negative tropes. For ages everyone said that P-40s were 'slow and unmaneuverable' but we know both of those things were false. It was slower than a Bf 109 and less manueverable than an A6M, but it was actually a reasonably fast and very maneuverable fighter by the standards of it's time. But P-40Es weren't making 360 mph in the field with a full fuel load. Maybe after they'd flown for an hour.


The P-40, from what I understand, was like a lot of WW2 fighters, especially American ones, in that it was right at the tipping point in terms of weight when they put in everything it needed for combat. I don't know about modern air shows and air races, (you can perhaps tell me) but I doubt they are putting 160 gallons of fuel, not to mention guns, self sealing fuel tanks, or all the armor. (I know they do keep some armor in some of those planes because I've seen the back of the seat armor on a P-40N at an airshow with my own eyes). But generally speaking, a fighter used in war conditions is going to be heavier and more draggy, and therefore not going to be as fast as one used in an airshow.

The difference in performance between the P-40F/L and the Allison powered P-40s, especially the E and the K, is basically that of altitude. The Allison can probably produce more horsepower, the K was rated for 1550 hp whereas the highest rating I've seen for the Merlin 28 / V-1650-1 is 1450 hp. I am pretty sure a P-40K could outrun a P-40F at Reno Air Races altitudes, (and probably a Bf 109 too, depending on the subtype). But the Merlin was still delivering around ~1100 hp at 20,000 ft, and that is where the speed came into play. And at that altitude, the P-40E was basically a sitting duck for the swift Bf 109F or MC 202 with their hydromatic superchargers, while the P-40F/L was still at least competitive.

At ~8500 lbs, a P-40 was close to overloaded. At ~ 8000 lbs, it was a lot more spry. The same aircraft that takes off to attack an enemy base might be a lot more snappy once it gets to the target. That is why you see such disparities quoted for nearly the same aircraft. A P-40F or P-40N with six guns and full fuel load has an initial climb rate of ~ 2,000 fpm, but with two guns out and a bit less fuel and armor, it bumps up to around 3,200 fpm. The difference is the weight.

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## GregP (May 14, 2021)

Hi Schweik, you are correct they don't put everything into a modern warbird ... MOSTLY.

There are several types of flying warbirds. One is just a flyer, and likely has had everything except what is needed to fly removed, and likely has the gun ports faired over and all excess weight removed. There are quite a few of these flying about. They generally outperform stock specs considerably due to lightness and better aerodynamics due to no armament and maybe fewer antennas.

A second type is a flying warbird that is pretty stock on the outside but is also still a LOT lighter than stock. An example might be the P-51A that the Planes of Fame flies. It is VERY light and had no armor, no guns or simulate gun weight, and is likely flying at just over 5,000 pounds! It is very sprightly, to say the least, for a P-51A. These birds may even have a glass cockpit installed! I've seen a Hawker Hunter with a full-glass cockpit in Boise, Idaho, U.S.A. . It was polished to a fine shine and had a "big" engine in it. I would not be at all surprised if it were capable of Mach 1+. Of course, nobody was pushing it to go that fast over Idaho since there is no supersonic corridor there AFAIK.

A third type warbird is the restoration to factory wartime stock condition. It has the armor, likely the guns (disabled, of course), and much of the stuff that is stock, but useless in peacetime. I have seen several of these type warbirds. The owners want them to represent a stock WWII bird. These perform slightly lower than wartime stock birds due to lack of late-war fuels being available to them. They run on 100LL fuel.

I'm not too sure I believe a P-40F with belly tank shackles installed went 370 mph. and I'm not too sure a stock P-40E was only a 345 mph airplane. I KNOW that John Paul's is faster than that, and his is pretty stock. Actually, I think the P-40E is Sue Paul's airplane! At least, she thinks it is , especially since it says SUE on the side.

I know what you mean about everyone repeating the specs from some test in some book. Of course, that is likely because nobody who currently owns a warbird wants to let someone flog their warbird doing performance tests unless someone is paying for a rebuild after the testing. And I don't know of anyone willing to fund a million+ dollar rebuild just to get a stock performance test on a bird that is more or less stock with an engine and propeller of unknown health. So, they are left with old performance test results. Oh well, it is the best we can do at this time and likely not to change, huh? As time goes on we are less and less likely to see any real performance testing. Presently, we are likely to see real performance test of a WWII warbird at a probability level of 0.00000148 or so ... and it is dropping all the time.

Cheers! In the end, I don't really know exactly how fast an average P-40E was. Of course, I can say the same for a P-40F. All I can say for sure is that the Merlin P-40s were better looking because the carb airscoop was not there and the fuselage was stretched to be longer than the P-40E fuselage was.


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## GrauGeist (May 14, 2021)

SaparotRob said:


> See? It wasn’t hard. Thanks GrauGeist.


Always glad to help!

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## Glider (May 14, 2021)

vikingBerserker said:


> Are we talking about the African P-39, or the European P-39?



More like the 
'I've been smoking something P39, where all my fantasies are real. 
Where all the thousands of pilots who flew it, all the engineers who worked on it, all the designers who designed it, were all so foolish and inept, that they couldn't see how these simple changes would have changed the world. Where the Fw190, P51A, Spit 12, Me109, Typhoon and all Japanese aircraft would bow down at the altar of the P39. 

The same P39 where all the pilots (with the exception of the Russians, granted) couldn't wait to get rid of it, just as fast as they can.

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## P-39 Expert (May 14, 2021)

Milosh said:


> Produce the chart.


Attached. Page 27.

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## P-39 Expert (May 14, 2021)

drgondog said:


> Nope - P-39 Faster (under 18K vs P-40F, then P-40F faster by 20mph), better acceleration (under 18K vs P-40F/K) and better climber (except vs P-40F/K from 18K ), much slower roll rate than P-40 (any model), less terminal dive speed, shorter range, less external load, less practical armament than P-40E and Subs, for most strafing and all air to air due to the issues with M-4 37mm cannon. Nobody in USAAF, RAF, Commonwealth, French and Italians were crying for more P-39s. *Faster, better climb, same or better range. External load? P-39 regularly operated in combat with a 110gal drop tank (8400lbs), P-40 had a hard time with anything over 50gal (8900lbs, same engine). Nobody crying for more P-39s? Soviets (main user) begging for them. *
> 
> Don't depend on your calculations -use USAAF Published Tables as reproduced on page 599 of AOHT, Table 100. Boundary conditions are 10 minutes of fuel for warm up, taxi, takeoff and landing. It allows for fuel used to climb to 10,000 feet, cruise and 10% of net ideal range for other factors - at more economical power speed. Below table values are for pure straight line range from take off to reserve point..
> 
> ...


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## Shortround6 (May 14, 2021)

Glider said:


> all the engineers who worked on it, all the designers who designed it,


 
Who all designed the P-39E/P-76 and P-63 to hold the engine/s that is claimed to fit into the P-39 with ease.


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## SaparotRob (May 14, 2021)

vikingBerserker said:


> Are we talking about the African P-39, or the European P-39?


"Where did you get the coconuts?"

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## Glider (May 14, 2021)

SaparotRob said:


> "Where did you get the coconuts?"



They were the ballast

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## buffnut453 (May 14, 2021)

I surrender....

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## Thumpalumpacus (May 14, 2021)

Shortround6 said:


> Nobody was shooting at me either.
> Couch was destroyed by fire as were curtains and molding. Wall phone on the other side of the room was melted. Scorch marks (light charing) about 3-4 feet down from the ceiling all around the room.



It's funny how our after-action reports and debriefings on a fire differed one from the other, even though my crew-chief was backing me up on a handline, or the other crash truck was set up only 100' away. They didn't see what I saw, and vice-versa. Perspective is a bitch.

Claims should clearly be compared to losses in order to tot them up straight as possible, because human perception is flawed for a number of reasons -- especially in a fast-flowing event.


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## varsity07840 (May 14, 2021)

GregP said:


> Regarding post #183 Schweik, I have the following:
> 
> View attachment 623139
> 
> ...



Since when was the P-40N in any of its sub types noted as an interceptor?


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## GregP (May 14, 2021)

The interceptor version of it had 4 machine guns. The other gun ports were fared over. It was a bit lighter, faster, and rolled & climbed better than the 6-gun variety.


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## Clayton Magnet (May 15, 2021)

GregP said:


> I'll stick with the Allison, myself, overall. In a perfect world where choice was an option, I'd have an Allison P-40 up until Dec 41, right about Pearl Harbor time. Then I'd fly a P-40F until Mar 43, at which time, I'd opt for a P-40N. I'd WISH for a P-40Q that would never show up.



I think you would be flying an Allison P-40 well beyond the Pearl Harbor timeline. 
When did the P-40F enter service? Pardon my ignorance, but I think there would be a significant gap between Dec 1941 and the introduction of P-40F's into combat.


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## MIflyer (May 15, 2021)

XP-40F flew on 25 Nov 1941. they built 1311 P-40F in 1942 and 700 P-40L with Merlin engines in 1943.

The P-40N-1-CU was the stripped model, with only 4 guns, no battery, and less fuel, and had top speed of 378 MPH. In contrast the P-40N-15 had a top speed of only 343 MPH at 15,000 ft. .

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## Clayton Magnet (May 15, 2021)

MIflyer said:


> XP-40F flew on 25 Nov 1941. they built 1311 P-40F in 1942 and 700 P-40L with Merlin engines in 1943.
> 
> The P-40N-1-CU was the stripped model, with only 4 guns, no battery, and less fuel, and had top speed of 378 MPH. In contrast the P-40N-15 had a top speed of only 343 MPH at 15,000 ft. .


I see, so you theoretically could have a P-40F right after Pearl Harbor. Disregard my previous post then


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## MIflyer (May 15, 2021)

Clayton Magnet said:


> I see, so you theoretically could have a P-40F right after Pearl Harbor. Disregard my previous post then



First P-40F to get into actual combat service that I know of was for Operation Torch. So it took about 11 months from first flight to combat deployment.

By the way, interesting thing was that whille all the P-40's at PH in Dec 41 were P-40B's, in the PI they were mostly P-40'E's with only one squadron of B's. I wonder if they sent the B's back to HI or if only one squadron of B's made it to the PI before E models came.


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## Greg Boeser (May 15, 2021)

But didn't you hear? the Japanese and Germans, when it was clear they were going to lose the war, systematically destroyed all loss records and wrote new ones to hide their true losses from the victorious Allies. I read it in a book once.

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## Greg Boeser (May 15, 2021)

PI was getting the most modern stuff because the War Dept. believed that it was the most likely target for Japanese aggression.

57th FG received P-40Fs in June 1942. Took off from _USS Ranger _on 19 July, 1942, bound for Africa. Arrived in Palestine for operational training by August 1st. First combat sorties 9 August 1942. First combat loss 14 August, 1942 near El Alamein.

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## BiffF15 (May 15, 2021)

Interesting shot of what appears to be AVG planes getting overhaul or re-assembly. Of note is the far left tail as it looks like a K or M model. Anyone have info on which versions the AVG actually flew?

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## fubar57 (May 15, 2021)

BiffF15
PM sent

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## Shortround6 (May 15, 2021)

Are you sure it was a book and not online?

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## Shortround6 (May 15, 2021)

Clayton Magnet said:


> I see, so you theoretically could have a P-40F right after Pearl Harbor. Disregard my previous post then



Yes, No, maybe????

Packard Built 45 Merlins in 1941, 26 of them in December. 
The British were supposed to get 2/3 of production and the US getting 1/3.

How this was divvied up I have no idea, every 3rd engine was labeled US. First 60 got to England/Canada and the next 30 go to the US and then repeat? batches of 200 and 100? 

AHT says that the prototype P-40F flew June 30th 1941 with a British engine. First P-40D had been delivered in May 1941. 
AHT says that the first production P-40F was delivered Jan 3rd 1942. 
May of 1942 sees P-40K versions start to be delivered. 
July 1st 1942 sees the P-40Fs of the 57th fighter group loaded onto the Carrier Ranger for shipment to Africa. It takes about the whole month of July to transport them for Rhode Island to the Gold coast (they are flown off about 100 miles from shore) and then to cross Africa and up to the middle east and their base in Palestine. It takes until Aug 31st for the 57 fighter group to operate as a single unit, individual squadrons had trained with British units on combat operations. 

So it is not wither or not you could *A* P-40F but if you could get enough to equipe a squadron or group, get them trained and get them to a combat theater. A Squadron of P-40Fs in Buffalo New York in January of 1942 is hardly going to affect any combat operation.

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## Greg Boeser (May 15, 2021)

Definitely a book. Probably about the Flying Tigers.

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## ThomasP (May 15, 2021)

re: P-40E/F/N speeds and ROC

Airframe________P-40E_______________P-40F_______________P-40N
Flying Weight___ 8680________________8980________________7400 lbs*

[email protected][email protected],500_________ [email protected],400_________ 378 [email protected],500 ft
Power_________1150________________ 1120________________1480 BHP*
_______________Military______________ Military______________WEP

ROCmax______ 1840________________ 2050________________ 2680 ft/sec
Power_________1000________________ 1120________________ 1125 BHP*
_______________Normal______________Normal______________ Military

The above is from a RAAF document. They used all 3 models, and I think at the same time for a brief period?

*Note:
1. Note that the P-40N is at extremely light flying weight, and WEP is used for Vmax and Military is used for the ROCmax, as opposed to Military and Normal for the P-4E&F. Military power for the P-40N is 1125 BHP at 15,000 ft (no RAM) so if we compare apples to apples the Vmax with Military would be ~346 mph for the same plane at 10,500 ft, or ~370 at 16-17,000 ft with RAM. The V-1710-81 engine in the P-40N has the same 1000 BHP Normal power as for the V-1710-39 in the P-40E, so the ROCmax would be about 2280 ft/sec for the 7400 lb weight.

2. If WEP (1440 BHP) for the V-1650-1 in the P-40F is used for speed the Vmax would be would be ~365 mph at 15-16,000 ft.
If Military power (1240 BHP) for the V-1650-1 in the P-40F is used for for climb the ROCmax would be ~2360 ft/min.

Both #1 and #2 assume that the aircraft are in the same flying condition as for the RAAF data.


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## GregP (May 15, 2021)

Reference post #220 above. The weights you have are not normal flying weights from what I find. Some are maximum takeoff weights and some I can't find at all. Don't know where you got the rates of climb, but I certainly have better numbers from credible places, and they are all better than yours. The P-40N is NOT at extremely light weight. 7,400 lbs was the normal flying weight. It was 6,000 lbs empty and 8,850 lbs maximum takeoff weight. Nobody flew combat at maximum takeoff weight. That was for ferry flights or perhaps as a bomber, it certainly wasn't for fighter combat!

We have and fly a P-40N and it very handily exceeds 3,000 feet per minute with full fuel and two people in it. The P-40N-1-CU had 4 guns. Later N's got heavier along with 6 guns.


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## ThomasP (May 15, 2021)

Hey GregP,

Sorry, I should have posted these but I did not find them right away. As I said, the values not under Note are from RAAF test data.










Also, I should have said "extremely light flying weight in comparison to the E&F models".

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## tyrodtom (May 16, 2021)

I raced circle track 17 years.
During a lot of that time one of my sponsors was a guy who took videos of every race. I got free videos.

I'd watch every bit of my race, slowed it down and watched it slow motion.

Sometimes incidents on video wasn't how I remembered them, and that was under the stress of just racing.

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## GregP (May 16, 2021)

I got my numbers in the Excel post above (post 201) here:

P-40 Performance Tests

and other places on the web. Seems like some discrepancies. But, I have never seen a WWII fighter with a max climb rate of less than 2,000 fpm before, and still don't think I have. Most of the less than 2,000 fpm climb rates are at normal power, not rated power.


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## ThomasP (May 16, 2021)

Hey GregP,

P-40N (actually a P-40K) No. 42-9987 test says basically the same as I have listed above, ie Vmax at WEP of 378 mph at 10,550 ft and at Military 371 mph at 17,300 ft (with RAM). ROCmax of 2680 ft/sec at 1105 BHP at 15,000 ft (Military), but adds the WEP ROCmax of 3720 ft/min. The TOGW as tested was 7403 lbs. (I do not have the detailed w&l numbers for the different variants of the P-40N, but with normal fuel (120 USgal) and ammo for 4x.50 cal TOGW should be about 7600 lbs+.)

P-40F report No. 41-13601 test says a bit different from what the RAAF report gives, ie Vmax of 364.5 mph at 19,270 ft at Military (1105 BHP). The ROCmax of 2210 ft/min at Normal (1240 BHP) is also a bit different, but the weight "as tested" is listed as 8450 lbs, which could account for the ~9 mph difference in Vmax and the 150 ft/sec difference in ROC.

P-40E No. 40-384 (w/o belly tank) test says basically the same as I have listed above for Vmax at Military (1150 BHP), ie 342 mph at 11,400 ft. The ROCmax is listed as 2400 ft/min at ~Military (ie 1120 BHP as opposed to 1000 BHP which is the actual Normal rating). The increased power used and the significantly lighter weight of 8011 lbs "as tested" easily accounts for the difference in ROC.

I am not sure where any significant numerical performance disagreement comes from?


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## P-39 Expert (May 16, 2021)

Merlin P-40F performance was almost exactly the same as contemporary P-39D/F/K/L when the same power settings are used.


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## Schweik (May 16, 2021)

P-39 wasn't doing so hot at 20,000 ft


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## fubar57 (May 16, 2021)



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## Schweik (May 16, 2021)

Both P-40F/L and P-40N had both lightweight 'interceptor' or more accurately 'vs. lots of fighters' configurations, general purpose configurations, and 'heavy' fighter-bomber configurations. The weight (not counting bombs) could vary by > 800 lbs. That is the difference in speed, rate of climb etc. It causes a lot of confusion. It's why top speed for a P-40N ranges from ~ 340 to ~380 mph in various tests, and P-40F similarly from ~350 mph to 370.

P-40F/L still had a better / higher performance ceiling (by about 4,000 ft) than any configuration of P-40N.

Note the P-40L is basically just a P-40F with the same stuff stripped out in the factory that they were already removing from P-40F in the field. In some cases they put a lot of it back (like the two wing guns and forward wing fuel tank) and made it back into a P-40F.

This is the test I referred to which showed 370 mph for P-40F or L (Kittyhawk II)

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## Schweik (May 16, 2021)

As for the P-39, which I know is a zombie horse (and who isn't sick of zombies these days) - it was a flawed design which also had significant potential. It was basically hard to learn to fly and hard to learn to optimize in terms of maintenance and field modifications (esp. vis a vis thing like the balance with the big gun and ammunition), which is something that all WW2 fighters contended with to some extent or another. The Russians made it work, partly because their Theater was ideal (where low altitude, short range fighters were the norm) it suited their fighting style (maintaining speed, shooting from short range) they did a long workup on it before throwing it into the breach (very different from Allied units in the Pacific), and perhaps most important of all, Russian pilots who flew it had already cut their teeth (and been through a brutal winnowing process) flying in combat with planes like I-16s, MiG 3s, LaGG-3s. If you lived through a year fighting the Luftwaffe with one of those, a P-39 was like a dream, both in terms of flight characteristics and performance. I.e. the I-16 etc. were all known to be 'twitchy' and easy to spin, and with difficult spin recovery traits. So if you were a pretty good pilot in one of those a P-39 would theoretically not be so much of a challenge, and then you can take advantage of the nice rate of climb, speed, streamlining (which helps keep speed up) armament etc.

The P-39 also had working radios, and I also believe it may have flown better in cooler or cold weather. They certainly had less problems winterizing them than they did with Hurricanes, Spitfires or P-40s.

It is and will always be a mystery, how the Russians made it work (and unlike some of our Luftwaffe fans, I believe they did) while nobody else could, but no more of a mystery than how the Finns did so well with the F2A compared to the USMC, and I think it boils down to many of the same factors.

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## P-39 Expert (May 16, 2021)

Schweik said:


> P-39 wasn't doing so hot at 20,000 ft



See my homemade graph below with figures from wwiiaircraftperformance.org (thanks) for the P-39K vs P-40F. P-39K was an early model with the -63 engine with 8.8 supercharger gears. Not the uprated -85 engine with the 9.6 gears.

In speed the P-39K and P-40F (blue dots) were absolutely equal at 19275ft with the P-39K being much faster below that altitude.

In climb the P-39K was superior at 3000rpm (red dots) but the P-40F (blue dots) was using best climb 2850rpm, at 3000rpm would have been about the same as P-39K.

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## Schweik (May 16, 2021)

Well that's interesting, but it's not official data right? If those numbers are right for the K it looks pretty good.


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## GregP (May 16, 2021)

Oh no ...







Why dontcha' pick a GOOD airplane to talk about?

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## SaparotRob (May 16, 2021)

Someone did just mention the Buffalo.

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## P-39 Expert (May 16, 2021)

Schweik said:


> Well that's interesting, but it's not official data right? If those numbers are right for the K it looks pretty good.


P-40 data was straight from wwiiaircraftperformance.org test dated July11, 1942.


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## GrauGeist (May 16, 2021)

Oh look, a Martlet!

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## Greg Boeser (May 16, 2021)

Stop trying to hijack this thread! The title is P-39 vs P-40. P-39 fanboys have a home here. As do P-40 fanboys.
If you want to talk Martlets, start your own thread.

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## pbehn (May 16, 2021)

Greg Boeser said:


> Stop trying to hijack this thread! The title is P-39 vs P-40. P-39 fanboys have a home here. As do P-40 fanboys.
> If you want to talk Martlets, start your own thread.


It is known in internet circles as "The tallest dwarf" thread.

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## GregP (May 16, 2021)

Tallest dwarf means it is low. 

So low, you'd have to look up to see whale crap.

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## pbehn (May 16, 2021)

GregP said:


> Tallest dwarf means it is low.
> 
> So low, you'd have to look up to see whale crap.


Not if it is an extremely tall dwarf.

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## DerAdlerIstGelandet (May 16, 2021)

Greg Boeser said:


> Stop trying to hijack this thread! The title is P-39 vs P-40. P-39 fanboys have a home here. As do P-40 fanboys.
> If you want to talk Martlets, start your own thread.

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## buffnut453 (May 16, 2021)

Oh look....a groundhog:







See? I can play along, too.

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## GregP (May 16, 2021)

We were told to start our own thread. So, here it is. Since I have to say or show something in here, here's my drawing of an FM-2 Wildcat ... nee ... Martlet.






And it ain't no P-39 ... but it DID establish a pretty good combat record with the U.S. Navy / Marines.

The FM-2 flew 12,925 combat sorties with 62 losses to AAA, 13 losses to enemy aircraft, and 75 operational losses, for a total of 150 losses on action sorties. They lost 283 on ship or ground, 164 on other flights, for a total of 447 losses on non-action sorties. They scored 422 aerial victories. They dropped 148 tons of bombs on target. All in all, a pretty good little airplane. Being a typical early carrier fighter, there were no "power" controls. The wings folded and unfolded manually, there was to hydraulic assist for anything, and the flaps were operated by vacuum, so they would tend to deploy asymmetrically and partially retract if speed built up past flap operating speed. Not even the landing gear was power-operated. It was a manual crank on the right side of the cockpit with 29 turns up and down. Once you started cranking the gear up or down, you could NOT let go of the crank or it could easily break your arm of leg as it wound down due to air pressure from forward velocity.

All for now.

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## pbehn (May 16, 2021)

All aircraft performance has a time component to it. The Martlet as it was known at the time was the first in service with British forces in UK in August 1940, when the BoB was still being waged. The P-40 started in British service in early 1941 while the P-39 was tried out and packed off to the USSR in late 1941.


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## Greg Boeser (May 16, 2021)

FM-2 s were called Wildcat Mk VI, so even your first post is wrong!

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## Greg Boeser (May 16, 2021)

Besides, everyone knows that the Bell Airabonita, the Navy's experiment to use the P-39 as a shipboard fighter was killed by entrenched anti-groundhog factions at BuAir, even though it would have surpassed all WW2 era Navy fighters.

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## pbehn (May 16, 2021)

Greg Boeser said:


> FM-2 s were called Wildcat Mk VI, so even your first post is wrong!


A proper Martlet doesnt have folding wings, why would you do such a thing, pure exhibitionism.


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## Admiral Beez (May 16, 2021)

Greg Boeser said:


> Besides, everyone knows that the Bell Airabonita, the Navy's experiment to use the P-39 as a shipboard fighter was killed by entrenched anti-groundhog factions at BuAir, even though it would have surpassed all WW2 era Navy fighters.


They should have kept the tricycle gear, why’d they change it?


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## Greg Boeser (May 16, 2021)

Tricycle gear would never work on a carrier, as history has proven.

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## SaparotRob (May 16, 2021)

I'm sure that one day, using this forum as guide, an aviation historian will convincingly write about the P-39 Groundhog.


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## pbehn (May 16, 2021)

Winkle Brown loved the P-39 as a carrier aircraft, he landed it on a carrier every chance he could get.

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## pbehn (May 16, 2021)

SaparotRob said:


> I'm sure that one day, using this forum as guide, an aviation historian will convincingly write about the P-39 Groundhog.


Google are working on it, as we post.

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## GregP (May 16, 2021)

With reference to post #7, weren't they assembling an F7F kit? All they really needed was modern glue and some sandpaper to smooth things out a bit.

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## GrauGeist (May 16, 2021)

SaparotRob said:


> I'm sure that one day, using this forum as guide, an aviation historian will convincingly write about the P-39 Groundhog.


Went to Google, entered "P-39 Groundhog" and lo and behold:

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## pbehn (May 16, 2021)

GrauGeist said:


> Went to Google, entered "P-39 Groundhog" and lo and behold:
> 
> View attachment 623524


Ive had that experience, I once googled something about Mosquito wing profiles and it linked me to one of my own posts here. Funny and worrying at the same time.

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## ThomasP (May 16, 2021)

re:"Not if it is an extremely tall dwarf."

Perhaps it is a Norse dwarf, which is ironically a giant (of sorts) in other mythologies.


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## Schweik (May 16, 2021)

pbehn said:


> Ive had that experience, I once googled something about Mosquito wing profiles and it linked me to one of my own posts here. Funny and worrying at the same time.



I have had that happen many times. What is worse is when you misspell something, google it with the incorrect spelling, and then find a post you made ten years ago with the bad spelling...

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## Greg Boeser (May 16, 2021)

It _does_ look like one of mine.

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## Greg Boeser (May 16, 2021)

I'm surprised at the number of times my posts here have been plagerized to other sites. Not that I care. Everything I have posted was lifted from somewhere else.

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## ThomasP (May 16, 2021)

Hey GregP,

re: "But, I have never seen a WWII fighter with a max climb rate of less than 2,000 fpm before, and still don't think I have. Most of the less than 2,000 fpm climb rates are at normal power, not rated power."

In this case the 1000 BHP Normal power is the same as Rated power, or the maximum sustained power. This was the Normal setting for most (all?) of the V-1710 types until the -89/-91 series (I think these were the first) in the P-38J&L, where it changed to 1100 BHP. I do not think that any of the other WWII aircraft powered by the V-1710 got Normal ratings higher than 1000 BHP. But the US often used Military for IROC (at least during performance tests) until the 5-15 min time limit was used up, and then throttled back off to Normal.

The F4F-3 and -4 are examples of this. The F4F-3 was originally credited with a respectable ROC in Normal power, but was later reduced considerably, and the F4F-4 entered service with a realistic ROC value due to in-service knowledge. The problem was that in pre-service one-off tests they managed to achieve pretty impressive ROCs, but in service the ROC had to be reduced to less than 2000 ft/min due to engine overheating.

The UK usually used whatever rating they could sustain for 30 min (or more) for Climb power as their equivalent to Normal (for example, 2850 rpm at +9 lbs for ~1120 BHP at SL in the Merlin XX). Later in the war, when engines were improved the UK also started using Military or even WEP for climb rates during tests and sometimes in combat when necessary.

I realize you probably know most of this, but others may not so I put it up as I did.


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## michaelmaltby (May 16, 2021)

"... packed off to the USA in late 1941."
And the Soviets .... first P-39s came from UK, IIRC


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## pbehn (May 16, 2021)

michaelmaltby said:


> "... packed off to the USA in late 1941."
> And the Soviets .... first P-39s came from UK, IIRC


Thats what happens when you are watching TV, I meant USSR lol.


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## DerAdlerIstGelandet (May 16, 2021)

Uggghh...

Another P-39 thread.

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## Thumpalumpacus (May 16, 2021)

DerAdlerIstGelandet said:


> Uggghh...
> 
> Another P-39 thread.



This here's a Wildcat thread, pardner!

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## SaparotRob (May 16, 2021)

Go Grumman! I'm from Long Island.

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## Thumpalumpacus (May 16, 2021)

Greg Boeser said:


> I'm surprised at the number of times my posts here have been plagerized to other sites. Not that I care. Everything I have posted was lifted from somewhere else.



Plagiarism is a compliment in one sense, enjoy the feeling! You must have said something that resonated with someone.


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## DerAdlerIstGelandet (May 16, 2021)

Oh no! 
A
 Admiral Beez
disliked my post. What will I do????

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## DerAdlerIstGelandet (May 16, 2021)

Thumpalumpacus said:


> This here's a Wildcat thread, pardner!

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## nuuumannn (May 16, 2021)

pbehn said:


> The Martlet as it was known at the time was the first in service with British forces in UK in August 1940, when the BoB was still being waged.



I think our times are slightly out here, the first Martlets _arrived_ in the UK in August 1940, and went to Scottish Aviation that month prior to service. The Martlet didn't enter FAA service until November 1940 with 802 Sqn, which lost all its aircraft when Glorious was sunk. Ten Martlets were sunk on board a freighter en route to the UK in October 1940. Carry on, chaps...

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## FLYBOYJ (May 16, 2021)

Greg Boeser said:


> I'm surprised at the number of times my posts here have been plagerized to other sites. Not that I care. Everything I have posted was lifted from somewhere else.


Oh I've seen stuff from here on other sites!!!

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## nuuumannn (May 16, 2021)

DerAdlerIstGelandet said:


> Oh no! @Admiral Beez disliked my post. What will I do????



Demand a recount and hold a riot...

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## nuuumannn (May 16, 2021)

I had to laugh at the quote below the ww2aircraft.net search: "I think the best solution would be to scrap the P-39"

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## Shortround6 (May 16, 2021)

The US testing procedure for climb was to use military power for 5 minutes and then reduce power to normal or max continuous. A fast climbing plane could hit 15,000 ft in 5 minutes. A slow climbing plane might just clear 10,000ft. If you compare the climb rate at 20,000ft they might be closer than the time to 20,000ft might suggest.
The Allison was running at 3000rpm for military power and 2600 rpm for "normal" or max continuous. Which had no time limit (as long as the fuel lasted 
The Merlin was rated at 3000rpm for full power or Military.
However climb rating was at 2850rpm for all but the early versions. But the climb rating was supposed to be used for 30 minutes or less. Obviously but unfortunately neither method tells us what the plane would do at the higher altitudes in combat, at full or military power.

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## Thumpalumpacus (May 16, 2021)

DerAdlerIstGelandet said:


> View attachment 623539



Six fifties up in your face, yo.

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## DerAdlerIstGelandet (May 16, 2021)

Thumpalumpacus said:


> Six fifties up in your face, yo.

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## GrauGeist (May 17, 2021)

FLYBOYJ said:


> Oh I've seen stuff from here on other sites!!!


Yeah...a glaring example would be my WWI German skin project for the Bf109 in IL-2: Sturmovik back around '08 (which involved considerable research and graphics work).
They didn't exist anywhere on the interwebs until I posted them in our gaming forum. It wasn't long after, that identical skins started popping up here and there in gaming forums and several "skin masters" laid claim to innovating the concept...

Well, to all those "experts" out there:
you're welcome.

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## GrauGeist (May 17, 2021)

nuuumannn said:


> I think our times are slightly out here, the first Martlets _arrived_ in the UK in August 1940, and went to Scottish Aviation that month prior to service. The Martlet didn't enter FAA service until November 1940 with 802 Sqn, which lost all its aircraft when Glorious was sunk. Ten Martlets were sunk on board a freighter en route to the UK in October 1940. Carry on, chaps...


Nooooo...the first Grummans the British received were French G-36As.

Therefore it would have been the "La Chat Sauvage"

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## ThomasP (May 17, 2021)

Hey Shortround6,

For the UK the Merlin XX series Climb rating (2850 rpm) was increased to 1 hr limit in early-1943.

For the V-1650-1 the US used 2650 rpm for maximum continuous (Normal) but had no separate Climb rating, at least not early-war. This is part of the reason why the P-40F did not have any significant ROC advantage in the US specifications literature. I have not been able to find any V-1650-1 Specific Engine Flight Charts dated after December 1942, so I do not know if this situation ever changed.

The UK and RAAF, on the other hand, used the UK Climb rating (2850 rpm) for the V-1650-1 in their P-40Fs.

Interesting mix.


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## Greg Boeser (May 17, 2021)

FLYBOYJ said:


> Oh I've seen stuff from here on other sites!!!


Possibly the funniest anecdote was a game designer who flew for Delta posted his harrowing first trip to Japan during the earthquake in 2011. He sent his followers a post to let them know he was safe and recount his experience. Well, someone forwarded it on to a friend and the next thing we know its all over the internet., he's getting called on the carpet for violating company policy about speaking to the press, and there are online debates raging about the authenticity of the story.

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## nuuumannn (May 17, 2021)

GrauGeist said:


> Nooooo...the first Grummans the British received were French G-36As.



That's right, the French order was de-Francofied by Grumman on the production line, before being sent to Scotland, where they were assembled by Scottish Aviation. The first Aeronavale 'Chat first flew on 10 May 1940, the day the Germans began their invasion. This is unlike the Curtiss Hawk 75s that arrived in the UK fully Francofied and required alteration before entering RAF service.

Actually I got something wrong in my previous post, 804 Sqn was the first British unit to receive those ex-French Martlets in October 1940, with 802 being formed from those 804 Sqn aircraft, in November. An 804 Sqn Martlet scored the type's first combat victory, over a Ju 88 in December.


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## glennasher (May 17, 2021)

nuuumannn said:


> I had to laugh at the quote below the ww2aircraft.net search: "I think the best solution would be to scrap the P-39"




Thank you and you're welcome! For whatever reasons, I've never been a fan of the 39. I won't apologize for that, apparently the USAAF felt the same way, it was used only because it was all they had at the time, and they gave them away whenever possible, or used them for target practice, which says a heckuva lot, right there.

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## pbehn (May 17, 2021)

nuuumannn said:


> That's right, the French order was de-Francofied by Grumman on the production line, before being sent to Scotland, where they were assembled by Scottish Aviation. The first Aeronavale 'Chat first flew on 10 May 1940, the day the Germans began their invasion. This is unlike the Curtiss Hawk 75s that arrived in the UK fully Francofied and required alteration before entering RAF service.
> 
> Actually I got something wrong in my previous post, 804 Sqn was the first British unit to receive those ex-French Martlets in October 1940, with 802 being formed from those 804 Sqn aircraft, in November. An 804 Sqn Martlet scored the type's first combat victory, over a Ju 88 in December.


History would be very different if the delivery schedules and state of readiness of the P-39 and F4F were reversed.


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## fastmongrel (May 17, 2021)

DerAdlerIstGelandet said:


> View attachment 623540



I would rather face a Grumman Wildcat than an angry Wildcat (Felis Silvestris). You have a chance of bailing out of the plane unscathed the cat will hang on and shred you

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## Peter Gunn (May 17, 2021)

DerAdlerIstGelandet said:


> Oh no!
> A
> Admiral Beez
> disliked my post. What will I do????


If it makes you feel better I can dislike your post too, or even give it the "Dumb" tag. Your choice.

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## DerAdlerIstGelandet (May 17, 2021)

Peter Gunn said:


> If it makes you feel better I can dislike your post too, or even give it the "Dumb" tag. Your choice.



Ooooh, dumb tag please!

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## Peter Gunn (May 17, 2021)

DerAdlerIstGelandet said:


> Ooooh, dumb tag please!


Your command is my wish.

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## DerAdlerIstGelandet (May 17, 2021)

Peter Gunn said:


> Your command is my wish.

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## MIflyer (May 17, 2021)

The situation between the F4F and the P-40/P-39 is an interesting one.

When the USAAC bought the YB-17 the USN realized that the vision of Gen Billy Mitchell was about to come true. When the USAAC intercepted the Italian liner Roma far out at sea, the USN got so scared they got Army HQ to forbid any such operations. When the tubosupercharged Y1B-17 came out the USN knew they had a huge problem. The Navy's carrier force was created to prevent the sitting duck situation that Billy Mitchell exploited in his demonstration. But while the F2A was an improvement over the F3F biplane, the Y1B-17 had a top speed equal to the F2A, but at TEN THOUSAND FEET higher. In wargames this would be fatal. In the pre-radar days of the 1930's, the first the USN would know of a Y1B-17 attack was when one appeared overhead. There was no chance of an F2A intercepting a Y1B-17, even if somehow they were able to see the bomber coming.

The first war any weapons system has to fight is in DC. After Mitchell's demonstration against the battleships the Washington Times headlines screamed that battleships were a waste of money; 15 years later it was all coming true. The USN was set up to lose the Battle of DC.

So the USN got with Grumman and reworked its failed competitor to the F2A with a two-stage mechanically supercharged engine, as was demonstrated by the Republic XP-41 - and rejected by the USAAC due to the superior performance of the tubosupercharged version of the same airplane, the AP-4; the result was the P-43. The Navy took the P-41 powerplant and added it to the F4F to produce the world's first two stage supercharged high altitude fighter to go into service.

The USAAC had been focused on the turbosupercharger as the answer to superior performance ever since the GE Pikes Peak test during WWI. But installing a turbo in a single-engined airframe proved to be too difficult with the available airframes and powerplants of the time. The XP-37 was a P-36 with a V-1710 and a turbo, but the cockpit had to be moved absurdly far aft, even if it was 50 mph faster than a P-36 above 20,000 ft.

On the XP-39 the turbo caused so much drag that the airplane was slower with it than without.

Eventually the USAAF got the P-38 and P-47 developed and deployed, proving that the turbo could do the job in a fighter as well as a heavy bomber, but in the meantime the USN's F4F was the only US fighter that enough high altitude performance to challenge the Zero and knock down the Betty bombers over Guadalcanal.

And ironically, it was the B-17 that scared the Navy into buying the F4F.

Now, if y'all will excuse me, I have to go put some paint on certain 1946 airplane.

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## Admiral Beez (May 17, 2021)

DerAdlerIstGelandet said:


> Oh no!
> A
> Admiral Beez
> disliked my post. What will I do????


I was trying to share my dislike and agreement with your Dislike of another P-39 threadjacking.

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## P-39 Expert (May 17, 2021)

FLYBOYJ said:


> 1. It won't make a difference, 2. You're trying to argue about something that doesn't exist. 3. Do you have Bell engineering drawings to show this installation in any area you mention? If you don't it doesn't exist! Stop with the hypothetical BS to support your arguments, it's getting old.


Here's the Bell drawings showing that the rear engine compartment is exactly the same size on both the P-63 (which had the auxiliary stage supercharger) and the P-39 (which did not).

Regarding moving the radio from the tail cone to above the engine, there are numerous public photos to verify that.


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## FLYBOYJ (May 17, 2021)

P-39 Expert said:


> Here's the Bell drawings showing that the rear engine compartment is exactly the same size on both the P-63 (which had the auxiliary stage supercharger) and the P-39 (which did not).
> 
> Regarding moving the radio from the tail cone to above the engine, there are numerous public photos to verify that.



Errrr - no. that is not an engineering drawing that shows a radio installation, all you're showing is station locations and skin thickness. "Could have, would have. should have." Face it, there is NO Bell installation for the movement of the radio to another part of the aircraft that "could have" or was actually done to any P-39 operated by the AAF in a combat situation, once again you're trying to fabricate something that never existed to sustain your argument. We (those of us who have actually weighed aircraft) have showed you that in the factory configuration, you cannot remove the front armor on any model of the P-39 without moving the C/G beyond aft C/G limits when expelling all the cannon ammunition and allowing the fuel to go below 1/4 full. Go back and look at the W&B chart the Greg put together. Now please put it to rest!!!!

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## GregP (May 17, 2021)

Ahhh ...







OR your P-39.

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## vikingBerserker (May 17, 2021)




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## fubar57 (May 17, 2021)

VS





WHO WOULD WIN?​

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## DerAdlerIstGelandet (May 17, 2021)

fubar57 said:


> View attachment 623621
> VS
> View attachment 623622
> 
> ...



That depends. Are we using real data, or self-made biased data that suits our narrative?

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## fubar57 (May 17, 2021)

Note that the P-39 Groundhog still has nose armour attached here. You can tell because the tail is off the ground

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## tyrodtom (May 17, 2021)

P-39 Expert said:


> Here's the Bell drawings showing that the rear engine compartment is exactly the same size on both the P-63 (which had the auxiliary stage supercharger) and the P-39 (which did not).
> 
> Regarding moving the radio from the tail cone to above the engine, there are numerous public photos to verify that.



If you call those two engine compartments the same length, it puts in question your definition of exact.
Evidently you didn't look at it very close.

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## Glider (May 17, 2021)

tyrodtom said:


> If you call those two engine compartments the same length, *it puts in question your definition of exact*.
> *Evidently you didn't look at it very close*.



Exactly


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## FLYBOYJ (May 17, 2021)

P-39 Expert said:


> Here's the Bell drawings showing that the rear engine compartment is exactly the same size on both the P-63 (which had the auxiliary stage supercharger) and the P-39 (which did not).
> 
> Regarding moving the radio from the tail cone to above the engine, there are numerous public photos to verify that.



Lastly, after all these discussions, did you ever ask yourself or wonder WHY the radio was all the way in the tail???

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## Clayton Magnet (May 17, 2021)

FLYBOYJ said:


> Lastly, after all these discussions, did you ever ask yourself or wonder WHY the radio was all the way in the tail???
> 
> View attachment 623632



That's easy, the radio gets better reception when it is closer to your comrades in formation behind you

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## pbehn (May 17, 2021)

If it wasnt in the tail the pilot had to have a tin foil hat?

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## FLYBOYJ (May 17, 2021)

Clayton Magnet said:


> That's easy, the radio gets better reception when it is closer to your comrades in formation behind you



Точно мой друг!


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## P-39 Expert (May 17, 2021)

FLYBOYJ said:


> Errrr - no. that is not an engineering drawing that shows a radio installation, all you're showing is station locations and skin thickness. "Could have, would have. should have." Face it, there is NO Bell installation for the movement of the radio to another part of the aircraft that "could have" or was actually done to any P-39 operated by the AAF in a combat situation, once again you're trying to fabricate something that never existed to sustain your argument. We (those of us who have actually weighed aircraft) have showed you that in the factory configuration, you cannot remove the front armor on any model of the P-39 without moving the C/G beyond aft C/G limits when expelling all the cannon ammunition and allowing the fuel to go below 1/4 full. Go back and look at the W&B chart the Greg put together. Now please put it to rest!!!!
> 
> View attachment 623592



A quick search resulted in five photos showing a radio installation under the rear canopy. The attached P-39N Flight Manual (page 6) shows a radio installed in the same location. Clearly a radio was mounted under the rear canopy on some models. Not all, but some.

Regarding the CG, we'll just have to disagree. Greg's chart does not have the radio in the tail cone to use as an adjustment. But deleting a 70-100lb slab of nose armor would more than be offset by moving (or removing) the IFF radio set in the tail cone, since it weighed 110-130lbs (AHT) and was farther away from the CG than the nose armor.


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## P-39 Expert (May 17, 2021)

The five minute military climb limit was in effect until mid 1942, after then it was increased to 15 minutes. About the same time that Allison gave up on the backfire screens and began using the aluminum intake manifold instead of the old flammable magnesium manifold.

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## GregP (May 17, 2021)

Hi thomas P,

I have flown in a P-40N and have spoken with people who operate P-40s of various sorts, including P-40E and M models. None of them have any trouble climbing at 2,500+ fpm at normal weights. Then again, none are being operated at very heavy weights, either. Most are operating just a small bit less than normal weight and none are at max weight, even with a belly tank. You should not be surprised by that since none have actual guns in them except for one very realistic P-40M restoration. And, none of them are limited to 1,000 HP. Most P-40s in combat in the Pacific didn't use only 43" - 43.5" of MAP. Most used 48" - 60" and the AVG used to use 70" - 75" if they needed to do so. Low MAP flight was the norm for training, not for front-line units. I'd think they would take off at normal power and cruise to battle at normal cruise power but, if it came to combat, my bet is they pushed the throttle forward and used what power it could make, without worrying overly much about MAP book maximums.

I worked on Allisons for about three years with Joe Yancey and ALL of them had no trouble getting to 48"+ MAP very briefly during break-in. Not exactly SURE of the HP they were making, but it was lifting the front wheels of a Ford F-350 dualie truck we were using as a test stand with a 6-blade club prop set for break-in loading. We never pulled 57" because it would pull the truck over. All we really needed to do was to run it sufficiently and with the correct fluids and break-in techniques to seat the rings. Once they seated, we didn't run it anymore. It was usually then time to crate it and ship it. Mostly, we could seat the rings in 7 - 9 hours of run time on the truck, usually for 25 - 30 minutes at a time, with careful throttle management. What you don't do is move the throttle quickly in either direction, open or closed.

Here's an Allison V-1710 backfire screen that I have:





It fits right into the intake manifold where it connects to the cylinder heads, assuming you have the right manifolds. You can see that it would restrict the intake flow and that is why they were not needed except in training. Once you know how to start an Allison, no screens are required. But, if you make a mistake on startup, you can blow gaskets. Same is true for ANY big WWII aero engine, including radials.

The worst was if a pilot pulled the power off too quickly when landing. That usually blew a gasket and dropped oil everywhere. Fires were one result of this mishandling.

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## FLYBOYJ (May 17, 2021)

P-39 Expert said:


> A quick search resulted in five photos showing a radio installation under the rear canopy. The attached P-39N Flight Manual (page 6) shows a radio installed in the same location. Clearly a radio was mounted under the rear canopy on some models. Not all, but some.



Ok - I'll give you that, "not all but some." Radio" - are we talking the actual communication radio or IFF?


P-39 Expert said:


> Regarding the CG, we'll just have to disagree. Greg's chart does not have the radio in the tail cone to use as an adjustment. But deleting a 70-100lb slab of nose armor would more than be offset by moving (or removing) the IFF radio set in the tail cone, since it weighed 110-130lbs (AHT) and was farther away from the CG than the nose armor.


The only way you'll know for sure is by doing the math with exact weights of the components.

BTW - he can adjust the chart just for that


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## FLYBOYJ (May 17, 2021)

P-39 Expert said:


> A quick search resulted in five photos showing a radio installation under the rear canopy. The attached P-39N Flight Manual (page 6) shows a radio installed in the same location. Clearly a radio was mounted under the rear canopy on some models. Not all, but some.
> 
> Regarding the CG, we'll just have to disagree. Greg's chart does not have the radio in the tail cone to use as an adjustment. But deleting a 70-100lb slab of nose armor would more than be offset by moving (or removing) the IFF radio set in the tail cone, since it weighed 110-130lbs (AHT) and was farther away from the CG than the nose armor.



Went back and looked at this - there is a RADIO behind the pilot on some models. There is ALSO one in the tail on *ALL* models!!!! Receiver/ Transmitter. This is not an optional installation, two units, two locations, "on some models."

From the manual you posted!







I can tell you flat out, the transmitter was not moved behind the pilot nor can it be!!!!

Same set up on the P-63.

So, the transmitter was left in the tail - I wonder why???


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## ThomasP (May 17, 2021)

Hey guys,

At the risk of fanning flames, P-39 Expert is correct as to the length of the engine compartment being the same in both the P-400/P-39 and the P-63.

_________________P-400_______ P-63
Aft Station_______228.50"_____ 231.50"
Fwd Station____ -138.25"_____-141.25"
Length___________90.25"__=___ 90.25"

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## ThomasP (May 17, 2021)

Hey GregP,

Any reasonable chance you could find out the actual TARE and TOGW for any of the Warbirds?


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## Airframes (May 17, 2021)

I seem to remember, reading, and probably seeing film footage somewhere, that the P-39, ( and / or the later "Kingcobra" ), was very successful when its weight was_* increased *_ - when it was flown ( by a real pilot, not by R/C ) as a target aircraft, when fighters attacked it, and fired at it, using frangible rounds !!!
So maybe it did have a use, after all !!!

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## wuzak (May 17, 2021)

fubar57 said:


> Note that the P-39 Groundhog still has nose armour attached here. You can tell because the tail is off the ground



But did it have its IFF removed?


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## tyrodtom (May 17, 2021)

ThomasP said:


> Hey guys,
> 
> At the risk of fanning flames, P-39 Expert is correct as to the length of the engine compartment being the same in both the P-400/P-39 and the P-63.
> 
> ...




You're right. My apologies P-39 expert.
I thought the engine compartment ended at frame 182 15/64 on the P-39, and frame 189.062 on the P-63, but it extends all the way to end of the triangular plate.

On the radios, if you look at a lot of WW2 era fighter cutaways and detail views you'll notice some builders even went so far as to mount the entire radio on bungee cords, and about as far from the engine as possible.
The transmitter has to be isolated from static sources as much as possible, or that's what you'll be transmitting, static.
With the old tube type radios, the transmitter was the had more tubes than the receiver, was more fragile, and heavier.

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## GregP (May 17, 2021)

I know it for some of the warbirds, but the information is not generally public. For instance, I have seen weight and balance for 20+ warbirds, but was usually asked not to pass the information along to anyone. I haven't except for the odd single variable here and there. You can find SOME weight and balances online, but not many for a currently-flying warbird.

Most are lighter than military stock, no surprise, but a few are a LOT lighter. Some are decently close to stock weight, but all are somewhat lighter. There is a lot of extraneous military equipment not needed for a modern warbird. For instance, some P-51s have the stock-appearing radios in them, but they are just shells. The birds really have modern radios that are a LOT lighter than a WWII unit. Modern batteries are lighter, armor plate is removed, drop mechanisms are removed, etc.

Generally, the % MAC is very close to stock, and WWII military fighters were designed so most loads would not generally put them anywhere close to out of CG for any reason.

I'll bet Der Adler and a few other moderators can verify that most operators don't make weight and balances public.


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## Shortround6 (May 17, 2021)

G


ThomasP said:


> Hey guys,
> 
> At the risk of fanning flames, P-39 Expert is correct as to the length of the engine compartment being the same in both the P-400/P-39 and the P-63.
> 
> ...




Great, now how wide and tall was the engine compartment in the last 15-30 inches? 





You may have the length (what was occupying the space/volume the 2nd stage takes up?) but do you have the room needed to fit the 2nd stage in the narrowing tail cone?


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## Schweik (May 17, 2021)

I feel like if they made that groundhog a bit lighter it could fly higher than the hawk.

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## Schweik (May 17, 2021)

Apparently they don't take the guns out of all of them, down in NZ they have a couple of them which are shooting (blanks, I assume) at air shows


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## special ed (May 17, 2021)

The RP-63 "Pinball" was not Radio Controlled. It was a piloted target with added armor to keep the frangible bullets from damaging airframe and pilot.


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## FLYBOYJ (May 17, 2021)

tyrodtom said:


> You're right. My apologies P-39 expert.
> I thought the engine compartment ended at frame 182 15/64 on the P-39, and frame 189.062 on the P-63, but it extends all the way to end of the triangular plate.
> 
> On the radios, if you look at a lot of WW2 era fighter cutaways and detail views you'll notice some builders even went so far as to mount the entire radio on bungee cords, and about as far from the engine as possible.
> ...



100% - I also believe on the later units, the IFF were part of the transmitter.


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## ThomasP (May 17, 2021)

I can not guarantee the data, but I have read that the engine section dimensions and structure were the same for the P-39x, P-39E, and P-63 - with only minor detail mods made for strengthening and ease of manufacture of the P-63. There were also a couple of added-modified access panels, along with modified upper sections for the changed air intake and rear of the canopy. The P-63 tail section was different from the aft station of the engine compartment on back.

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## Schweik (May 17, 2021)

GregP said:


> Hi thomas P,
> 
> I have flown in a P-40N and have spoken with people who operate P-40s of various sorts, including P-40E and M models. None of them have any trouble climbing at 2,500+ fpm at normal weights. Then again, none are being operated at very heavy weights, either. Most are operating just a small bit less than normal weight and none are at max weight, even with a belly tank. You should not be surprised by that since none have actual guns in them except for one very realistic P-40M restoration. And, none of them are limited to 1,000 HP. *Most P-40s in combat in the Pacific didn't use only 43" - 43.5" of MAP. Most used 48" - 60" *and the AVG used to use 70" - 75" if they needed to do so.* Low MAP flight was the norm for training, not for front-line units.* I'd think they would take off at normal power and cruise to battle at normal cruise power but, if it came to combat, my bet is they pushed the throttle forward and used what power it could make, without worrying overly much about MAP book maximums.



I don't have nearly as much first hand experience as Greg, but I have spoken to several P-40 pilots, originally when I was a kid as my father was a journalist for Life magazine with a special interest in war veterans in general and WW2 fighter pilots in particular. I was a little quiet kid he had trained to sit still and shut up (often with the help of a model airplane) but I listend to them talk and occasionally got to ask a few questions of my own after they were done with formal interviews and started drinking. Later in life I've talked to the guys flying the warbirds at airshows, especially the P-40s which I had a special interest in. They do apparently push those engines sometimes, more than I expected, though for regular airshow flying I was told low throttle settings were sufficient, partly because they weren't carrying a full load of fuel.

When I was a little kid I didn't know enough to ask about things like manifold pressure, but one consistent story I remember hearing from guys from the 49th FG and the 23rd FG (former AVG) was that once they had figured out how to push the planes they were able to outrun the Japanese fighters and they would run for their lives, gather their wits, and sometimes come back for another shot. One guy was telling my Dad how he was so shit scared in an air battle he swore to himself he'd never get into an airplane again, but once he pulled away and realized he had gotten free and clear, the panic passed, and he started getting angry and went back looking for targets.

Many units seem to have gone through a shakeout process where they learned they could push the engines a bit harder than the manual said. But Shortround pointed out to me a while back, and I believe he is correct - the heavy MAP overboosting was only doable at pretty low altitudes, and not everybody did it. It certainly put the engine at risk. What is true however is that the manual increased the standard boost levels, just like with so many RAF fighters and others around the world - and P-40s were being used with higher boost, both the Allison and the Merlin-engined ones. This isn't always accounted for in the shorthand on these planes (for example that a P-40K had up to 1550 hp at low altitude according to the WEP setting in the manual).

Allison specifically made changes to strengthen the crank case and crank shafts among other things, to make the engines better able to handle the higher boost, but it's also worth pointing out, as it says in the famous Allison memo on the subject, once the the higher-geared Allison engines came out with the P-40M, the very heavy overboosting was likely to be dangerous and was more likely to blow the engine.

I believe most of this should apply to both P-39s and P-40s obviously, and also P-51A (et al), though I don't know as much detail about the combat history of the P-39.


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## Schweik (May 17, 2021)

special ed said:


> The RP-63 "Pinball" was not Radio Controlled. It was a piloted target with added armor to keep the frangible bullets from damaging airframe and pilot.



That must have been such a depressing, not to say scary job I would think...


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## buffnut453 (May 17, 2021)

Schweik said:


> That must have been such a depressing, not to say scary job I would think...



Concur...not sure I'd be willing to fly an aircraft where my entire survival was dependent on the armourers working on a different airframe. "Ooops! Sorry sir. Forgot what I was doing and put regular bullets in the belt instead of frangible. Ever so sorry, sir!"


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## SaparotRob (May 18, 2021)

To go up in a P-39 and the mission is to be shot at. 
Who did that guy piss off?


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## GrauGeist (May 18, 2021)

SaparotRob said:


> To go up in a P-39 and the mission is to be shot at.
> Who did that guy piss off?


To be honest, it would be far better to have rookies plugging away at you rather than angry Japanese or Germans...

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## Schweik (May 18, 2021)

I was wondering the same thing. I bet there are some amusing stories behind the people who were forced to do this. Hell of a use for a formidable aircraft like a kingcobra too. I wonder if it was some kind of anti-commie thing? I was at an airshow where they had a kingcobra flying and the guy on the loudspeaker went on ad nauseum about the various mundane training duties they used it for, but never once mentioned the Soviets actually using it in combat.

Found a pretty good article about the 'pinball', with a few brief pilot commentaries

Just Shoot Me | Military Aviation | Air & Space Magazine


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## P-39 Expert (May 18, 2021)

Only about 300 P-63s were converted to armored targets. No P-39s that I know of.

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## P-39 Expert (May 18, 2021)

FLYBOYJ said:


> Went back and looked at this - there is a RADIO behind the pilot on some models. There is ALSO one in the tail on *ALL* models!!!! Receiver/ Transmitter. This is not an optional installation, two units, two locations, "on some models."
> 
> From the manual you posted!
> 
> ...


My whole point is that radios COULD be mounted behind the pilot, which they often were. This is just one way that CG could have been adjusted after removing the nose armor. I'm sure Bell had other ways of adjusting CG. The Soviets removed the IFF radios in the tail (and wing guns) as unnecessary and kept the nose armor and it didn't seem to affect their flying qualities. 

Would be fun if Greg P could add the IFF radio in the tail cone to his P-39 CG chart.


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## Peter Gunn (May 18, 2021)

I do recall last year in another thread where P-39 Expert pointed out (and I believed) that the engine compartment WAS large enough to hold the 2 stage supercharger. As SR6 points out, is the tail cone wide/tall enough to take it? Well, if it fit in the P-63 I don't think it's much of a stretch to say the P-39 could handle it, I'm sure Bell engineers (they did give us the supersonic X-1 after all) were capable of making it work.

Now if the 2 stage engine is installed, being longer and by extension then, more weight aft, how's the CG looking then? Making it fit is one thing, W & B issues would seem to me to be worse than ever but I'm no engineer.

I've always loved the P-39 for it's looks (it is literally my second favorite WWII a/c after the Mustang) and it is frustrating to think it _could_ have been much better than it was but them's the breaks I guess.


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## FLYBOYJ (May 18, 2021)

P-39 Expert said:


> My whole point is that radios COULD be mounted behind the pilot, which they often were. This is just one way that CG could have been adjusted after removing the nose armor. I'm sure Bell had other ways of adjusting CG. The Soviets removed the IFF radios in the tail (and wing guns) as unnecessary and kept the nose armor and it didn't seem to affect their flying qualities.
> 
> Would be fun if Greg P could add the IFF radio in the tail cone to his P-39 CG chart.



You are correct about "a" radio mounted behind the pilot *BUT* the transmitter *CANNOT be moved, *so in the bigger picture you're still in the same boat by removing any nose armor. And again, I believe the later transmitter units had the IFF (SCR-535A) incorporated in the installation.


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## SaparotRob (May 18, 2021)

Aside from my "humorous" answer, I believe those target 'Cobras were piloted by WASP pilots. Those guys were really under appreciated and certainly deserved more from Uncle Sam.


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## Clayton Magnet (May 18, 2021)

Schweik said:


> Apparently they don't take the guns out of all of them, down in NZ they have a couple of them which are shooting (blanks, I assume) at air shows




Does anyone know if those are actual M2's? I may be wrong, but I suspect those are some sort of pyrotechnics in the wings, simulating gunfire. Even with blank firing adaptors, they probably aren't allowed to fire them off that close to crowds.

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## Milosh (May 18, 2021)

P-39 Expert said:


> My whole point is that radios COULD be mounted behind the pilot, which they often were. This is just one way that CG could have been adjusted after removing the nose armor. I'm sure Bell had other ways of adjusting CG. The Soviets removed the IFF radios in the tail (and wing guns) as unnecessary and kept the nose armor and it didn't seem to affect their flying qualities.
> 
> Would be fun if Greg P could add the IFF radio in the tail cone to his P-39 CG chart.


Have you ever done a proper Weight and Balance for all these changes you say could be done?


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## P-39 Expert (May 18, 2021)

SaparotRob said:


> Aside from my "humorous" answer, I believe those target 'Cobras were piloted by WASP pilots. Those guys were really under appreciated and certainly deserved more from Uncle Sam.


WASPs were ladies, right? And they definitely weren't treated fairly by the AAF IMO.

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## FLYBOYJ (May 18, 2021)

Milosh said:


> Have you ever done a proper Weight and Balance for all these changes you say could be done?



We did one a few months ago, Greg came up with a W&B calculator on an Excel spread sheet. The data used in the chart was based on what was shown in the W&B charts within the flight manuals. Removing the wing guns helped the effort was well as some armor close to the C/G, but it was clearly shown removal of the armor in the nose would have the C/G go beyond C/G limits aft if all the cannon ammo (and I believe the nose guns IIRC) were expended and if fuel was allowed to go beyond 1/4 empty.


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## special ed (May 18, 2021)

There was a restored TBF many years back which used Acetalene (sp) for the gunflashes. They ran afoul of the USN and the FAA when they made a dummy torpedo run on a docked USN ship.

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## P-39 Expert (May 18, 2021)

Peter Gunn said:


> I do recall last year in another thread where P-39 Expert pointed out (and I believed) that the engine compartment WAS large enough to hold the 2 stage supercharger. As SR6 points out, is the tail cone wide/tall enough to take it? Well, if it fit in the P-63 I don't think it's much of a stretch to say the P-39 could handle it, I'm sure Bell engineers (they did give us the supersonic X-1 after all) were capable of making it work.
> 
> Now if the 2 stage engine is installed, being longer and by extension then, more weight aft, how's the CG looking then? Making it fit is one thing, W & B issues would seem to me to be worse than ever but I'm no engineer.
> 
> I've always loved the P-39 for it's looks (it is literally my second favorite WWII a/c after the Mustang) and it is frustrating to think it _could_ have been much better than it was but them's the breaks I guess.


The auxiliary stage weighed about 175lbs (AHT) but remember it replaced the coolant tank which was moved up right behind the pilot basically on the CG. The coolant weighed 149lbs and the tank weighed 17lbs for a total of 166lbs. So basically the auxiliary stage supercharger replaced the coolant/tank for CG purposes. And a four blade propeller would be needed to absorb the extra power at high altitude which would add more weight to the nose.

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## GrauGeist (May 18, 2021)

P-39 Expert said:


> WASPs were ladies, right? And they definitely weren't treated fairly by the AAF IMO.


WASP - Women Air Force Service Pilot (USAAF)
WAVES - Women Accepted for Volunteer Emergency Service (USN)
And while the Marine Corps did not have women pilots, they did have a Women's Reserve (no acronym) - my Aunt Patricia was one.

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## SaparotRob (May 18, 2021)

special ed said:


> There was a restored TBF many years back which used Acetalene (sp) for the gunflashes. They ran afoul of the USN and the FAA when they made a dummy torpedo run on a docked USN ship.


Some people just can’t take a joke.

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## Greg Boeser (May 18, 2021)

What's the big deal? If it dropped a Mk. XIII the ship was perfectly safe anyway.

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## P-39 Expert (May 18, 2021)

FLYBOYJ said:


> You are correct about "a" radio mounted behind the pilot *BUT* the transmitter *CANNOT be moved, *so in the bigger picture you're still in the same boat by removing any nose armor. And again, I believe the later transmitter units had the IFF (SCR-535A) incorporated in the installation.


The pilot's manuals for both the P-39K/L and N show two radios, the 522 voice and the 535 IFF radios. Appears the voice radio was mounted behind the pilot and the IFF radio was mounted in the tail. Why couldn't it be moved? It was deleted completely from Soviet P-39s.


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## Milosh (May 18, 2021)

FLYBOYJ said:


> We did one a few months ago, Greg came up with a W&B calculator on an Excel spread sheet. The data used in the chart was based on what was shown in the W&B charts within the flight manuals. Removing the wing guns helped the effort was well as some armor close to the C/G, but it was clearly shown removal of the armor in the nose would have the C/G go beyond C/G limits aft if all the cannon ammo (and I believe the nose guns IIRC) were expended and if fuel was allowed to go beyond 1/4 empty.


But, did Expert use it?


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## FLYBOYJ (May 18, 2021)

P-39 Expert said:


> The pilot's manuals for both the P-39K/L and N show two radios, the 522 voice and the 535 IFF radios. Appears the voice radio was mounted behind the pilot and the IFF radio was mounted in the tail. Why couldn't it be moved? It was deleted completely from Soviet P-39s.



Well after some research, I think I figured this out.

The SC-535 is the IFF radio. It was removed by the Soviets as you say. So we'll remove that from discussion for now...

The Radios in the P-39 - An SCR 274 or an SCR-522.

*The SCR 274* was a 5 unit system, 3 receivers and 2 transmitters. It would be obvious you need to keep the transmitter away from RF interference, so most of the time you would have a transmitters mounted as far away as possible, so that's why it was initially shoved in the empennage with the control head in the cockpit. This system was sometimes contained in one metal box (US Installations) or had separate unit installations (RAF).

This is what the installation looked like in the P-51B. Although there is more equipment in this aircraft, the basic units are shown.







Now it seems the British and Australians used the same system but those units were not contained in one box and they seemed to fit in the area behind the pilot.






Why did the Aussies install their system this way? To move the C/G forward? It would seem you would have heat issues. I seen photos and cut-aways of the P-39 D with nothing in the deck above the engine but the "boxed" SCR-274 unit was firmly in the empennage.






Here's early P-39s with the RAF - no radio behind the pilot.






And a P-39N






Unless you use the same set-up was the Aussies and "unbox" the system, I don't think it was going to fit behind the cockpit.


*The SCR 522* was also a 2 system unit but was eventually combined into one box. It replaced the SCR 274. It also came with a separate "dynamotor" or power supply. The SCR 522 was 16 x 12 x 10 and weighed 49 pounds. The dynamotor was 12 x 8 x 6 and weighed 37 pounds. The control head was about 2 pounds and was in the cockpit.






Now it seems on some P-39Qs part or all of this installation was squeezed into the deck behind the pilot.





This P-39Q was from the 4th Reconnaissance Squadron.












P-39Q of the 82d Reconnaissance Squadron (Fighter), 71st Reconnaissance Group, New Guinea 28 May 1944, they seemed to have this installation *but was it all radios or photo equipment?*

*Now with along with this installation, was the IFF removed from US aircraft? I would say not if they were in theater.*

So at the end of the day - are you going to be able to move the radios? If you have the "boxed" SCR 274 US set up - no.

If you use the RAAF SCR 274 set up - yes.

If you use the SCR-522? It looks like it was factory or field installed *but were all the components installed on the deck or within the radio compartment in the empennage*?

So I'll somewhat stand to be corrected.

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## FLYBOYJ (May 18, 2021)

Milosh said:


> But, did Expert use it?


He did to a point.


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## Shortround6 (May 18, 2021)

P-39 Expert said:


> The coolant weighed 149lbs and the tank weighed 17lbs for a total of 166lbs




Another yes, no and maybe.

The coolant may well have weighed 149lbs but it was not all (or even most of it) in the "tank".
The tank is an overflow tank to hold the expanded fluid as the engine heats up.
Most of the coolant is in the engine block and the radiator with a bit in the lines connecting them. 

Much like many cars have a small plastic tank near the radiator with a hose connecting the tank and the radiator at the pressure cap. As the coolant gets hot and expand the over flow goes through the tube and into the "expansion tank" and once the coolant cools it is syphoned back into the cooling system. 

At any rate, there is no 149 lbs to move, Modern Prestone coolant weighs about 10lbs per gallon. I think that Allison may have been running a 70-30 mix? 

Tank is only going to hold a few gallons even when full.


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## Schweik (May 18, 2021)

GrauGeist said:


> WASP - Women Air Force Service Pilot (USAAF)
> WAVES - Women Accepted for Volunteer Emergency Service (USN)
> And while the Marine Corps did not have women pilots, they did have a Women's Reserve (no acronym) - my Aunt Patricia was one.



I ran across a long series of photos of these lady pilots, quite an impressive bunch, made me wonder what happened to them after the war.

Apparently they were not who were flying the P-63 target planes though, the article I linked has a few quotes from pilots who flew them, a combination of young officers right out of flight school and combat veterans with 80+ missions. The job wasn't to just fly around and get shot at by ground based AA though, instead they made fake attack runs at B-17s while the gunners shot at them, which some of them seem to have enjoyed. It sounded quite hazardous though and there were many accidents.

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## Schweik (May 18, 2021)

Clayton Magnet said:


> Does anyone know if those are actual M2's? I may be wrong, but I suspect those are some sort of pyrotechnics in the wings, simulating gunfire. Even with blank firing adaptors, they probably aren't allowed to fire them off that close to crowds.



I believe they are real, but blanks. Anyway they have put real ones back into P-40s and P-51s that I've seen (on video, not in person yet)

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## Schweik (May 18, 2021)

This is one of those ones shown flying in the New Zealand air show


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## SaparotRob (May 18, 2021)

Pretty neat.


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## Schweik (May 18, 2021)

Yeah that first one inside the hanger was particularly intense. I think we may be seeing two different types of M2 here, the fast firing one and the older slower firing one. You can see quite a difference.


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## Shortround6 (May 18, 2021)

Blanks are not going to cycle a gun like live ammo. In fact you may need a restrictor in the bore to get full automatic functioning? 

On recoil operated gun having no bullet certainly affects the recoil. They can play games with the powder and other things.

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## Schweik (May 18, 2021)

I mean...

1) Watch the videos. Clearly they are shooting bullets, you can see the casings and the links piling out. You can see the flames and smoke coming out of the gun barrels. I don't think they are shooting live ammo inside of a hangar. And I don't think that's some kind of pyrotechnic trick, with the links and shell casings pouring out. If so that would be very well coordinated.
2) I don't know what you are talking about re: blanks. When I was in the service, we did exercises with blanks loaded into all of our guns, including the machine guns, which worked along with the Miles gear (laser tag, essentially). It worked, more or less. We did have caps on the end of the weapons but I think that was for safety (to ensure nobody shot a live round out of one).


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## Shortround6 (May 18, 2021)

Blank-firing adaptor - Wikipedia


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## Clayton Magnet (May 18, 2021)

Shortround6 said:


> Blanks are not going to cycle a gun like live ammo. In fact you may need a restrictor in the bore to get full automatic functioning?
> 
> On recoil operated gun having no bullet certainly affects the recoil. They can play games with the powder and other things.


I am assuming they are not M2's, but some sort of gas operated alternative. Or a very light and modified barrel, light enough to cycle the gun with only gases leaving the barrel


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## GrauGeist (May 18, 2021)

Without the resistance of the bullet being driven down the barrel by the expanding gasses, the cyclic rate of the weapon will be affected.
The barrel restrictor helps to maintain a certain amount of gas pressure needed to properly work the MG's firing cycle.

*edit* just saw SR's post with the link - that should have better info than my post


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## ThomasP (May 18, 2021)

From Airborne Radio Equipment Handbook 1943 edition SC3858A:

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## GrauGeist (May 18, 2021)

Those Dynamotors are cool - GE and Motorola were still using them on automotive two-way radios as late as the late 80's.


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## FLYBOYJ (May 18, 2021)

ThomasP said:


> From Airborne Radio Equipment Handbook 1943 edition SC3858A:
> 
> View attachment 623864



Very cool, this answers a lot of my questions - but there still seems to be a later installation on the shelf behind the pilot, this is shown in the P-39Q flight manual.


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## Schweik (May 18, 2021)

In this video, you can see the size of the shell casings. They look like .50s to me. I've shot M2s before.



Compare this to a pyrotechnic replica .50 doing simulated shooting via propane and O2


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## GrauGeist (May 19, 2021)

Quite a few restored warbirds have original weapons installed and are functional (where allowed by law).
Their blanks will be actual casings with fully functional primers (electric in the case of German weapons) with a gunpowder load appropiate for blank firing topped off by a wad and are loaded into the belts just as if it were live ordnance.
The weapon functions the same as if it were live: the blank round is loaded from the belt, the blank discharges and the shell is ejected and the next round is loaded into the chamber from the belt during the cycle.

It looks realistic because it is - the only difference is that the aircraft isn't hurling several hundred rounds downrange. The "bang", smoke and cascade of casings is genuine.

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## P-39 Expert (May 19, 2021)

Milosh said:


> But, did Expert use it?


I had saved the chart for future use, but it would no longer let me make any adjustments. Said my excel subscription had expired, which I never had. Great chart and fun to play with, wish the radio could be included.

As I remember it, as the nose ammunition was expended the CG moved back but never got past the aft limit.


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## P-39 Expert (May 19, 2021)

FLYBOYJ said:


> Well after some research, I think I figured this out.
> 
> The SC-535 is the IFF radio. It was removed by the Soviets as you say. So we'll remove that from discussion for now...
> 
> ...


Excellent work, and very thorough. Just a note, the radio location issue is only for the 1942 P-39-D/F/K/L models with the lower powered V-1710-35/63 engines to save weight. The 1943 N/Q models had good performance at normal gross weight, no reduction was needed. Although the Soviets did delete the wing guns and IFF radio on most of their P-39s.


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## FLYBOYJ (May 19, 2021)

P-39 Expert said:


> Excellent work, and very thorough. Just a note, the radio location issue is only for the 1942 P-39-D/F/K/L models with the lower powered V-1710-35/63 engines to save weight. The 1943 N/Q models had good performance at normal gross weight, no reduction was needed. Although the Soviets did delete the wing guns and IFF radio on most of their P-39s.



Thank you - A couple of things

If you get the station of where the radio compartment is located you can calculate the removal of the IFF unit. BTW, you were confusing me calling this area a "tail cone." It's actually an aft fuselage or empennage.

I believe on US aircraft, one of the reasons why you had all or part of the radio unit moved to the shelf behind the pilot was because of the IFF installation. There was only so much room in the radio compartment so the remainder of the comm system had to go somewhere. I believe the area behind the pilot was initially ignored for radio installations were because of RF and heat issues, but that's my opinion.


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## FLYBOYJ (May 19, 2021)

P-39 Expert said:


> I had saved the chart for future use, but it would no longer let me make any adjustments. Said my excel subscription had expired, which I never had. Great chart and fun to play with, wish the radio could be included.
> 
> As I remember it, as the nose ammunition was expended the CG moved back but never got past the aft limit.


In it's original configuration yes.

Remove the nose armor, expend all the nose ammo and allow fuel to go below 1/4 tank - No


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## P-39 Expert (May 19, 2021)

FLYBOYJ said:


> In it's original configuration yes.
> 
> Remove the nose armor, expend all the nose ammo and allow fuel to go below 1/4 tank - No


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## pbehn (May 19, 2021)

If you take out the nose armour could you put some lead in to balance things? Or am I over thinking this?


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## P-39 Expert (May 19, 2021)

I worked Greg's CG chart again and deleted the nose armor, nose cannon and MG ammunition, wing guns and wing ammunition and the CG was one half inch past the aft limit before any adjustment for the radio in the aft fuselage. Was not able to delete the fuel but it is located on the CG. For some reason was not able to attach the graph to this post.


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## P-39 Expert (May 19, 2021)

pbehn said:


> If you take out the nose armour could you put some lead in to balance things? Or am I over thinking this?


Purpose of deleting the nose armor is to save weight.


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## pbehn (May 19, 2021)

P-39 Expert said:


> Purpose of deleting the nose armor is to save weight.


I thought I was in too deep.

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## FLYBOYJ (May 19, 2021)

pbehn said:


> If you take out the nose armour could you put some lead in to balance things? Or am I over thinking this?



You are to a point - to make a difference you have to take weight out of the tail


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## GregP (May 19, 2021)

Here's an accurate scale representation of the P-39Q and P-63A.





The P-39Q is 30" 2" long and the P-63A is 32" 8" long. In the above pic, I lined up the front of the exhaust manifolds since they are bolted to the engine. I went to the aft part of the air intake. Note the length added to the P-63 is aft of the windscreen. 

As it happens, *we have a P-63 in the final stages of work just before first engine run. We also have a P-39, complete with external engine and nose case*. I volunteer every week on Tuesday, so I was there yesterday, but I was working on parts for another aircraft. Next week, I'll get measurements of the same areas shown above. Now, our P-63 is not using a 2-stage V-1710, but the engine compartment is stock. The engine we are using is a 100-series and makes about 1,600 hp at full MAP. Of course, it will very rarely see 1,600 hp and will likely be operate at the 1,200 - 1,400 hp max limit when it flies, and only at an airshow at that. Most of the time, it should see that limit only on takeoff and initial climbout.

Easy since we have the subjects right there. Talk with you then.

Cheers.

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## FLYBOYJ (May 19, 2021)

P-39 Expert said:


> I worked Greg's CG chart again and deleted the nose armor, nose cannon and MG ammunition, wing guns and wing ammunition and the CG was one half inch past the aft limit before any adjustment for the radio in the aft fuselage. Was not able to delete the fuel but it is located on the CG. For some reason was not able to attach the graph to this post.



22Gallons of fuel (1/4) tank puts it out of C/G

Now something to consider - This data was taken from the P-39Q flight manual. The manual did not show what radio (or IFF) was installed for weight and balance purposes, that would be specific to the aircraft and found in the maintenance records that follow the aircraft.


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## SaparotRob (May 19, 2021)

Okay everybody, let's all kick in a couple hundred grand US to the Planes Of Fame Museum in Chino, California. GregP (not Greg) and his guys build and rebuild these two airplanes to the mods suggested here and see if we can do what Bell, the USAAF, the RAF, the RCAF, the RAAF couldn't. I'm sure we can get one of our Forum members with a pilot's license drunk enough to take up the modified 'Cobras and see if it would work. We'll settle it once and for all. Then we can fix the Botha.

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## GregP (May 19, 2021)

Actually, the P-63 is at Yanks Air Museum, located on the same airport. I am a member of both museums. Planes of Fame has a P-39 and Yanks has a P-39 and a P-63. They are just about to have first-run on the P-63 engine any day now. Actually, it HAS run, but not in the airplane connected to the propeller. It was run in on a test stand by Joe Yancey.

In point of fact, most bulkheads are hollow. That is, they aren't solid across the entire fuselage. So, it is possible and even likely the engine mounts on the two airplanes are the same since the engine mounts plates are integral to the engine block. It is highly unlikely that the aux stage is left hanging out in space all by itself, supported only by a driveshaft housing. See below.







So, while the power section engine case block, nose box and integral supercharger are all supported by the engine mounts, it is also likely the case that the auxiliary supercharger stage is supported by a mount that is simply not present on the P-39. I'll check on this next Tuesday and report back.

By the time an aux-stage Allison was available, nobody in the USAAF wanted the P-39. So, it would never have had the aux-stage Allison fitted in the first place. The P-63 was an update of the P-39, longer and bigger, and had very little in common with the P-39 save some few components that could be shared. None of the airframe was interchangeable. But, you all know this and an argument saying the Allison 2-stage could be mounted in the P-39 ignores reality completely. It was a non-starter.

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## glennasher (May 19, 2021)

I feel sorry for the womenfolk who turned in their aluminum pots and pans for recycling into P-39s and P-63s, it must have been pretty upsetting to waste all those good cooking utensils for that dog of an airplane.

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## Ovod (May 19, 2021)

glennasher said:


> I feel sorry for the womenfolk who turned in their aluminum pots and pans for recycling into P-39s and P-63s, it must have been pretty upsetting to waste all those good cooking utensils for that dog of an airplane.



Did they use recycled scrap aluminium to build aircraft in the war? They don't use scrap metal to build aircraft today, it' got to be "virgin" aluminium, straight from the ground. 

You're probably being a a bit negative about Bell aircraft from the war - it served its role quite well during the war, especially on the Eastern front.


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## pbehn (May 19, 2021)

Ovod said:


> Did they use recycled scrap aluminium to build aircraft in the war? They don't use scrap metal to build aircraft today, it' got to be "virgin" aluminium, straight from the ground.
> 
> You're probably being a a bit negative about Bell aircraft from the war - it served its role quite well during the war, especially on the Estern front.


There was a famous propaganda campaign "throw in all your pots and pans, we'll make them into Spitfires" by Beaverbrook in UK. It was great for getting everyone feeling involved, it resulted in mountains of pots pans and lots of other stuff that wasnt made into Spitfires. Pans into Planes – thewartimekitchen.com

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## P-39 Expert (May 19, 2021)

FLYBOYJ said:


> 22Gallons of fuel (1/4) tank puts it out of C/G
> 
> Now something to consider - This data was taken from the P-39Q flight manual. The manual did not show what radio (or IFF) was installed for weight and balance purposes, that would be specific to the aircraft and found in the maintenance records that follow the aircraft.
> View attachment 623943


Like I said, without fuel, nose armor and nose ammunition the CG is .5416" aft of the aft limit. A hair over a half inch. Like I also said, if the 71lb nose armor is removed an adjustment would be necessary like moving the radio in the aft fuselage. I always said that a CG adjustment would be necessary and suggested the radio could be moved to offset the deletion of the nose armor.


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## P-39 Expert (May 19, 2021)

GregP said:


> Here's an accurate scale representation of the P-39Q and P-63A.
> 
> View attachment 623941
> 
> ...


Your photo shows the P-39 engine compartment to actually be a few inches longer than the P-63, probably the result of slightly different scale. Both are exactly the same length.


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## Marcel (May 19, 2021)



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## pbehn (May 19, 2021)

Marcel said:


> View attachment 623958


Looks like he needs some weight in his tail.


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## Marcel (May 19, 2021)

pbehn said:


> Looks like he needs some weight in his tail.


Did you see that canon in the nose? That's at least 2 inches....

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## P-39 Expert (May 19, 2021)

Shortround6 said:


> Another yes, no and maybe.
> 
> The coolant may well have weighed 149lbs but it was not all (or even most of it) in the "tank".
> The tank is an overflow tank to hold the expanded fluid as the engine heats up.
> ...


Silly me, assuming that the coolant was in the coolant tank. 

From Design Analysis of the P-39 Airacobra "The Prestone expansion tank is so arranged that when filled to the level of the filler neck, when the airplane is in its normal rest position it will contain it's proper amount of coolant and the proper amount of expansion space."

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## FLYBOYJ (May 19, 2021)

P-39 Expert said:


> Like I said, without fuel, nose armor and nose ammunition the CG is .5416" aft of the aft limit. A hair over a half inch. Like I also said, if the 71lb nose armor is removed an adjustment would be necessary like moving the radio in the aft fuselage. I always said that a CG adjustment would be necessary and suggested the radio could be moved to offset the deletion of the nose armor.


Not that fast...

We still don't know how much the IFF removed would do for the C/G as we don't know the arm and weight - additionally we also don't know what part of the radio configuration will negate ALL equipment from the radio bay in the empennage, so this is still an enigma. At this point it's about the operator's configuration of the aircraft. Did the Russians put any equipment in the empennage radio bay? My feeling is if you have anything in that bay you're going to have C/G issues or come close to the most aft C/G in the conditions stated.

A hair over a half inch will not cause the aircraft to fall out of the sky (if you fly straight and level and do NOT do any form of aerobatics) but it will be more than likely against normal operating regs of the day to fly it that way as the aircraft is already tail heavy in it's normal configuration.


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## P-39 Expert (May 19, 2021)

AHT says the IFF radio weighs 110-130lbs and it is farther away from the CG than the nose armor plate so it should move the CG forward within range.


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## GregP (May 19, 2021)

Reference post #839.

No, it doesn't.


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## pbehn (May 19, 2021)

FLYBOYJ said:


> You are to a point - to make a difference you have to take weight out of the tail


Funnily enough the Spitfire had the CoG issues when they inserted bigger engines, they just put circa 90lbs (5x 17.5) in the tail of a MkIX and around 150lbs ( if I remember correctly) in the MkXIV. No fuss at all, carry on chaps.

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## GrauGeist (May 19, 2021)

P-39 Expert said:


> Silly me, assuming that the coolant was in the coolant tank.
> 
> From Design Analysis of the P-39 Airacobra "The Prestone expansion tank is so arranged that when filled to the level of the filler neck, when the airplane is in its normal rest position it will contain it's proper amount of coolant and the proper amount of expansion space."


Notice the key word "expansion tank"?
That's not a reservoir or storage unit, it's a tank that allows for the coolant someplace to go as the operating temps increase.
It is essentially the same as the plastic bottle that's attached to you car's radiator - which is usually 1/3 to 1/2 full.


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## FLYBOYJ (May 19, 2021)

P-39 Expert said:


> AHT says the IFF radio weighs 110-130lbs and it is farther away from the CG than the nose armor plate so it should move the CG forward within range.


It should if it was installed to begin with. If the W&B configuration shown in the POH was meant not to include the IFF, we're back to square one.

Now with all this said, what we're showing "could have" been easily figured out by the Soviets. Why did they leave the armor plate in the nose while removing the IFF? My feeling is to move the C/G forward making the aircraft handle better...

And again - did they put anything in the radio bay?


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## Shortround6 (May 19, 2021)

Later planes may have changed a bit but expansion tank capacity 3 gallons. About 30lbs at most. plus the weight of the tank.


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## nuuumannn (May 19, 2021)

Right then! Glad that's sorted (again... eyeroll). So, how 'bout that Fw 187, eh guys...

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## Greg Boeser (May 19, 2021)

Why are we arguing about putting in a different engine in the P-39 when Bell actually designed a successor aircraft to the P-39 to hold that very engine? 
It's like saying the B-17 would have been a super bomber if Boeing had only put R-3350s in it.

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## wuzak (May 19, 2021)

If the engine bay of the P-39 and P-63 were the same, would I be right in assuming that the auxiliary supercharger in the P-63 was not actually in the engine bay?


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## fubar57 (May 19, 2021)

Ahhhhh...the Fw 187 Murmeltier

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## Shortround6 (May 19, 2021)

wuzak said:


> If the engine bay of the P-39 and P-63 were the same, would I be right in assuming that the auxiliary supercharger in the P-63 was not actually in the engine bay?


Lets not forget the the P-39E/P-76 





Granted it was _designed_ to hold the Continental V-1430 (or some version of it) so may have had some extra length to accommodate that engine which came in handy when they wanted to put the two stage Allison in it when Continental couldn't produce an airworthy V-1430 (or tell Bell/USAAC when one would be available).

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## nuuumannn (May 19, 2021)

Greg Boeser said:


> Why are we arguing about putting in a different engine in the P-39 when Bell actually designed a successor aircraft to the P-39 to hold that very engine?
> It's like saying the B-17 would have been a super bomber if Boeing had only put R-3350s in it.



I think you've nailed it, Greg. If the P-39 was as good as it is being trumpeted, why did Bell build the P-63?

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## GregP (May 19, 2021)

Well, they DID re-engine a B-17. Here's one with four Allisons.






A very pretty bird, indeed! And here's one with four radials and one big turboprop.






and here's one with four turboprops.






and here's one with a Wright turboprop.






Seems like nobody is satisfied with a war-winning bomber, huh? They weren't stisfied with just the B-17. Here's a B-29 with four ALlison V-3420s.






Here's a jet fighter (McDonnell XF-88) with a turboprop in the nose in addition to the turbojets.






They're NEVER satisfied, are they?

If they had a rating scale for fighters in WWII by country, the P-39 and the Buffalo would be fighting a good bout for the bottom of the heap. Maybe we should have sent hordes of P-39s to the Finns. Look what they did with a few Buffalos, and the P-39 could easily beat a Buffalo ... well ... at low altitudes anyway.

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## nuuumannn (May 19, 2021)

GregP said:


> Well, they DID re-engine a B-17. Here's one with four Allisons.


Yeah, but when Boeing wanted a better bomber they built the B-29, but again, if the P-39 was living up to expectations, why build the P-63? Why not just put the new engine in the P-39, like other Greg hinted at?

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## Milosh (May 19, 2021)

Those B-17s with nose engines were test mules for the nose engine.


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## Shortround6 (May 19, 2021)

nuuumannn said:


> Not the point, Greg, when Boeing wanted a better bomber they built the B-29, but again, if the P-39 was living up to expectations, why build the P-63? Why not just put the new engine in the P-39?




Could have been that while with a very large shoehorn, a set of tin snips and a rather cavalier attitude about weights/balance and CG you could get the engine into the engine bay. However some bright young spark figured out that since the P-39 was skating on very thin ice in regards to cooling with the existing radiator and oil coolers fitting and engine that generated several hundred more HP in the cylinders and flew higher (thinner air doesn't cool as well) they were headed for disaster without larger radiator/s and oil cooler/s?

1125hp to prop plus about 100hp for internal friction plus around 250hp to drive the supercharger equals around 1475hp in cylinders for a cooling load at 15,000ft for the single stage engine.

1125hp to the prop plus about 100hp for internal friction plus around 125hp to drive the engine supercharger plus around 300hp to drive the auxiliary supercharger equals around 1650hp in cylinders, now trying to cool that heat load (about 12% greater) at 22,000ft where the air is only 79% as dense (Lbs per cubic ft) is not going to end well.

Figures are a little rough but do point out the problem.

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## nuuumannn (May 19, 2021)

Shortround6 said:


> Could have been that while with a very large shoehorn, a set of tin snips and a rather cavalier attitude about weights/balance and CG you could get the engine into the engine bay. However some bright young spark figured out that since the P-39 was skating on very thin ice in regards to cooling with the existing radiator and oil coolers fitting and engine that generated several hundred more HP in the cylinders and flew higher (thinner air doesn't cool as well) they were headed for disaster without larger radiator/s and oil cooler/s?
> 
> 1125hp to prop plus about 100hp for internal friction plus around 250hp to drive the supercharger equals around 1475hp in cylinders for a cooling load at 15,000ft for the single stage engine.
> 
> ...



Yup, about sums it up. Wuz gonna say dat too... ;D

The answer is that the P-39 _was not _living up to expectations. The combat environment had outgrown it.

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## Shortround6 (May 19, 2021)

BTW the coolant expansion tank in the P-63 held 1 1/2 gallons per the flight manual, which also says that the P-39 tank held 3 gallons.


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## GrauGeist (May 19, 2021)

Shortround6 said:


> BTW the coolant expansion tank in the P-63 held 1 1/2 gallons per the flight manual, which also says that the P-39 tank held 3 gallons.


Does it say if the tank was brass or aluminum by any chance?


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## P-39 Expert (May 20, 2021)

Greg Boeser said:


> Why are we arguing about putting in a different engine in the P-39 when Bell actually designed a successor aircraft to the P-39 to hold that very engine?
> It's like saying the B-17 would have been a super bomber if Boeing had only put R-3350s in it.


Just timing. The new engine was in production from April 1943 but the new P-63 airframe wasn't ready until that October. Seven months wasted in mid 1943 when those engines could have been installed in P-39s.


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## buffnut453 (May 20, 2021)

P-39 Expert said:


> Just timing. The new engine was in production from April 1943 but the new P-63 airframe wasn't ready until that October. Seven months wasted in mid 1943 when those engines could have been installed in P-39s.



Have to disagree here. Seven months is barely enough time to install and flight test a new engine, then you have to change the production lines. Seven months won't get a single souped-up P-39 to a squadron.

Given that Bell already had the P-63 in the works, it makes no sense to syphon off scarce design and engineering resources to up-engine the P-39. Bell clearly felt that the P-39 was at the end of it's development potential. No point investing in a dead-end.

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## Shortround6 (May 20, 2021)

P-39 Expert said:


> Just timing. The new engine was in production from April 1943 but the new P-63 airframe wasn't ready until that October. Seven months wasted in mid 1943 when those engines could have been installed in P-39s.




Been over this before, the engine was not in full production and did not pass a type test until Nov 1943, didn't pass WEP test until Dec 1943. 

So the basic premise seems to be, take low production engine that had not passed a type test and requires more cooling system capacity than the engine in the P-39 and just cram it into the P-39 which already has problems meeting the cooling requirements of the engine they were already using? 

As shown above, even if you do not use the WEP capability of the new engine and only try to use the Military power at a higher altitude (pretty much the whole point of the exercise) you need a totally revamped cooling system to make use of the altitude capability. 




buffnut453 said:


> *Seven months is barely enough time to install and flight test a new engine,* then you have to change the production lines. Seven months won't get a single souped-up P-39s to squadrons.



Buffnut is pretty much on the money, you not only need a bigger radiator and oil coolers, you need around 25-30% more airflow through the cooling ducts. 
Please go back and see the XP-39, One of the reasons the turbo was dropped was that they had to totally redesign the cooling system for the engine even without a turbo. 

Now if you have a limited engineering staff do you work on finishing up the P-63 or do you put it on hold and try to sort through this P-39/two stage engine mish mash.

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## FLYBOYJ (May 20, 2021)

P-39 Expert said:


> Just timing. The new engine was in production from April 1943 but the new P-63 airframe wasn't ready until that October. * Seven months wasted in mid 1943 when those engines could have been installed in P-39s*.



Also keep in mind that during WW2 (and even today), big component items like engines didn't belong to the manufacturer, they were "Government Furnished Equipment" and any reallocation had to be approved by the government.

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## gordonm1 (May 20, 2021)

Schweik said:


> This is one of those ones shown flying in the New Zealand air show



This one looked like 6 50's with only two firing on the left side like #3 was jammed.


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## Peter Gunn (May 20, 2021)

What I'm getting from all this discussion is that in order for a Bell aircraft (be it P-39 or P-63) to be competitive with contemporary Luftwaffe types is that the stars need to perfectly align.

First Allison has to be producing the 2 stage engine in quantity no later than mid 1940 (approximately 3 years early?).

Then Bell has to make sure the airframe design is able to fit the engine (from 3 years in the future) with the aforementioned 2 stage supercharger (with sufficient cooling, not to mention W&B)

and the government must be on board with channeling the 2 stage engine to the Airacobra program.

Is that about right or am I missing something? While we're at it, maybe that beer truck runs over a certain procurement officer (drgondog's assessment from an earlier thread) and the Mustang gets the 2 speed 2 stage supercharged Merlin a year early and P-51's are available for LR escort in Mid 1943.

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## P-39 Expert (May 20, 2021)

Peter Gunn said:


> What I'm getting from all this discussion is that in order for a Bell aircraft (be it P-39 or P-63) to be competitive with contemporary Luftwaffe types is that the stars need to perfectly align.
> 
> First Allison has to be producing the 2 stage engine in quantity no later than mid 1940 (approximately 3 years early?).
> 
> ...


Standard late 1942 P-39N compared with a contemporary FW190A-6. Pretty competitive. Plus P-39 was more maneuverable and had longer endurance.


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## P-39 Expert (May 20, 2021)

buffnut453 said:


> Have to disagree here. Seven months is barely enough time to install and flight test a new engine, then you have to change the production lines. Seven months won't get a single souped-up P-39 to a squadron.
> 
> Given that Bell already had the P-63 in the works, it makes no sense to syphon off scarce design and engineering resources to up-engine the P-39. Bell clearly felt that the P-39 was at the end of it's development potential. No point investing in a dead-end.


Really only three months to get a new engine into a fighter per Vees for Victory. No production stoppage when the P-39 changed from the -35 to the -63 to the -83 and the -85. The -93 was a bit more complicated but doable in my opinion.


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## buffnut453 (May 20, 2021)

P-39 Expert said:


> Really only three months to get a new engine into a fighter per Vees for Victory. No production stoppage when the P-39 changed from the -35 to the -63 to the -83 and the -85. The -93 was a bit more complicated but doable in my opinion.



I refer the honorable gentleman to Shortround's post #866.

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## Peter Gunn (May 20, 2021)

What Buffnut said. You do realize we're not talking about swapping out a couple of small block Chevy's in a Camaro right?


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## Peter Gunn (May 20, 2021)

P-39 Expert said:


> Standard late 1942 P-39N compared with a contemporary FW190A-6. Pretty competitive. Plus P-39 was more maneuverable and had longer endurance.


Those would be great if they were sort of legible.

However, I think I see what you're driving at.

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## P-39 Expert (May 20, 2021)

Peter Gunn said:


> Those would be great if they were sort of legible.
> 
> However, I think I see what you're driving at.


Especially since the highest power setting was not available for most of the war.


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## P-39 Expert (May 20, 2021)

Shortround6 said:


> Been over this before, the engine was not in full production and did not pass a type test until Nov 1943, didn't pass WEP test until Dec 1943.
> 
> So the basic premise seems to be, take low production engine that had not passed a type test and requires more cooling system capacity than the engine in the P-39 and just cram it into the P-39 which already has problems meeting the cooling requirements of the engine they were already using?
> 
> ...


Low production engine? Same engine as contemporary 1710 models, only real variables were S/C gear ratios and E model remote reduction gear. The only new production item was the auxiliary stage which was just an impeller in a diffuser driven by a small shaft. It's not like Allison just trucked over the first -93 engine to the Bell plant and said "Surprise!" Bell had known for literally years that this engine was coming, prep work would have been done to insure as smooth a transition as possible.

Regarding cooling, as you say we have discussed this before. Just a 1325HP Allison with a higher critical altitude. I know I know the air is less dense at high altitude but it is a lot colder too. This engine was only put into a P-39E three times but I believe it could have been done. Dead horse beaten.

And the P-39 wasn't the only AAF fighter that had cooling problems. From wwiiaircraftperformance.org the P-38G tested 2/10/43: "Prestone cooling does not meet Air Corps cooling requirements." This is in addition to the intercooling deficiencies. From the P-47 tests of 6/18/42, 12/26/42 and 1/28/43: "Above speeds are for maximum rate of climb, but the engine does not meet the AAF cooling requirements at these speeds." And this is at very mediocre climb rates. P-51A test 4/2/43 didn't meet Air Corps cooling requirements in speed or climb. 6/11/42 test: "cooling temperatures were 7 degrees warmer than the maximum temperature allowed." P-51B test of 4/24/44 said "coolant temperature would be critical throughout the climb in a range of 120-135 degrees." All the AAF fighters had cooling problems except the P-40 as far as I can tell.

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## pbehn (May 20, 2021)

P-39 Expert said:


> Standard late 1942 P-39N compared with a contemporary FW190A-6. Pretty competitive. Plus P-39 was more maneuverable and had longer endurance.


By late 1942 the USA had P-47, P-38 and P-51A, the UK had the Spitfire IX and the first Griffon variant the MkXII. In what role is the P-39N better than those and was it competitive with the Fw 190A-6 at all altitudes?


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## P-39 Expert (May 20, 2021)

pbehn said:


> By late 1942 the USA had P-47, P-38 and P-51A, the UK had the Spitfire IX and the first Griffon variant the MkXII. In what role is the P-39N better than those and was it competitive with the Fw 190A-6 at all altitudes?


P-39N was competitive with late 1942 P-38F/G, P-47B/C and P-51A. Yes it was.

The FW190A-6 vs P-39N graphs are graduated by altitude. Better climb and ceiling.


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## pbehn (May 20, 2021)

P-39 Expert said:


> P-39N was competitive with late 1942 P-38F/G, P-47B/C and P-51A. Yes it was.
> 
> The FW190A-6 vs P-39N graphs are graduated by altitude. Better climb and ceiling.


If the P-39N was a match for the Fw-190 at all altitudes then the P-51A would be an ideal long range escort, wouldnt it?

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## P-39 Expert (May 20, 2021)

pbehn said:


> If the P-39N was a match for the Fw-190 at all altitudes then the P-51A would be an ideal long range escort, wouldnt it?


Sure, for medium bombers but not high altitude B-17 or B-24. P-51A didn't have the climb and ceiling of the P-39N since it was 1000lbs heavier with the same engine.


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## pbehn (May 20, 2021)

P-39 Expert said:


> Sure, for medium bombers but not high altitude B-17 or B-24. P-51A didn't have the climb and ceiling of the P-39N since it was 1000lbs heavier with the same engine.


Better to send whole fleets of bombers unescorted then rather than try it, why not reduce the altitude of B-17s? The P-39 was sent away from UK after 1 mission, the P-40 was sent to N. Africa after a few dozen, the Mustang MkI was used for tactical recon. This is all because the Allison engine didnt have high altitude performance and neither did the P-39N. This is why the P-38 had turbos and the P-51 got a two stage Merlin, to pretend otherwise is just denial.

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## eagledad (May 20, 2021)

Gentlemen

Granted, the opinion expressed below was from a pilot in the PTO. However, I think we are missing the whole point of why the P-39 was not valued by the USAAF:

“It took no time to realize that I had a poor combat airplane. It had served its purpose well in Panama, but this was a brand new ball game. The P-39 had _no range_ to get you where the real action was, poor service ceiling, poor rate of climb, and it wasn’t the best in a dive.” Capt W.K. Giroux, quoted from Pacific Sweep page 232. (Italics by me)

Granted, he was talking about early P-39 and P-400’s that were well used for the most part, and he was stationed with the 36th fighter Squadron, 8th Fighter Group in Port Moresby New Guinea. However, he had some 30 missions in the P-39, so his opinion should carry some weight.

In my opinion, stuff what ever more powerful engine you can into the P-39, adjust the weight to keep proper CG, but without extra fuel, you will still have a fighter that has “no range to get you to the real action”. 

So I agree with the consensus, adding a more powerful engine will not be a simple switch. It appears to me to get the most out of a more powerful engine, it makes more sense for a new airframe. Bell did this with the P-63. However, the King Cobra was still hampered by lack of range (for USAAF purposes).

My 2 cents,

Eagledad

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## P-39 Expert (May 20, 2021)

See the chart in post #869. 38000ft ceiling and 31000ft combat ceiling. Better than P-40, P-51A, F4F, F4U, F6F, FW190, Typhoon, A6M2 and Ki-43. About the same as P-38F/G, P-47C and Me109G and better climb below 30000ft. Not as good as Spitfire IX. That about covers it for 1942/43 fighters.

P-39N had a higher rated engine than the vastly overweight P-400s rejected by the UK.


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## P-39 Expert (May 20, 2021)

eagledad said:


> Gentlemen
> 
> Granted, the opinion expressed below was from a pilot in the PTO. However, I think we are missing the whole point of why the P-39 was not valued by the USAAF:
> 
> ...


Agree with most of what you said. 1942 P-39 was way too heavy for the engine power available. Dump the wing guns, nose armor plate and IFF radio and a 7150lb P-39 would have done whatever the Captain asked. Endurance was actually over 3 hours which was better than single seat European fighters and enough to conduct operations in New Guinea that were mostly defensive in 1942.

It did make sense to design the new P-63 around the new engine, but it did not make sense to waste seven months in the middle of 1943 waiting on the airframe to be finished.


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## pbehn (May 20, 2021)

P-39 Expert said:


> See the chart in post #869. 38000ft ceiling and 31000ft combat ceiling. Better than P-40, P-51A, F4F, F4U, F6F, FW190, Typhoon, A6M2 and Ki-43. About the same as P-38F/G, P-47C and Me109G and better climb below 30000ft. Not as good as Spitfire IX. That about covers it for 1942/43 fighters.
> 
> P-39N had a higher rated engine than the vastly overweight P-400s rejected by the UK.


So he people there at the time were wrong then? Like many you underestimate the effect of that 21 miles of water. What worked in Africa and Russia didnt work across that stretch of water, and after D-Day altitude performance wasnt so important, neither was range, although it is 21 miles at the shortest point it quickly becomes 100.


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## P-39 Expert (May 20, 2021)

pbehn said:


> So he people there at the time were wrong then? Like many you underestimate the effect of that 21 miles of water. What worked in Africa and Russia didnt work across that stretch of water, and after D-Day altitude performance wasnt so important, neither was range, although it is 21 miles at the shortest point it quickly becomes 100.


I don't understand your comment about overwater flights.


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## FLYBOYJ (May 20, 2021)

P-39 Expert said:


> Agree with most of what you said. 1942 P-39 was way too heavy for the engine power available. Dump the wing guns, nose armor plate and IFF radio and a 7150lb P-39 would have done whatever the Captain asked. Endurance was actually over 3 hours which was better than single seat European fighters and enough to conduct operations that were mostly defensive in 1942.



*The AAF was not going to dump the IFF in operational units*, so drop that, and depending on radio configuration, you cannot remove the armor plate in the nose as been shown over and over again! I have some more data coming to include Russian P-39 configurations.

And speaking of IFF - you have said that the Russians "removed" their IFFs. An IFF was a sensitive unit and even had a destruct system built into it. Do you have an *accurate source* to say the Russians were "removing" their IFFs or were P-39s were being delivered with IFFs not installed?!


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## Glider (May 20, 2021)

P-39 Expert said:


> Agree with most of what you said. 1942 P-39 was way too heavy for the engine power available.
> Dump the wing guns,


 and lose valuable firepower


> nose armor plate


 And be shot to bits by anyone with an LMG. Put it another way. I can think of loads of aircraft who added armour for protection but cannot think of any that took armour out. P39 do you have any examples?


> IFF radio


 And suffer much higher losses as they normally had other functions such as identifying aircraft lost in bad weather. Helping your side sort out who was friendly and who wasn't. Again to put it another way. Why do you think it was installed in the first place?
]

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## pbehn (May 20, 2021)

P-39 Expert said:


> I don't understand your comment about overwater flights.


Well then I suggest you read about it and think about it. The Channel is a DMZ or no mans land, both sides have to cross it and both sides had heavy AA on the coast, you can cross at sea level if you want but that means you can be bounced at zero feet. Apart from heavily defended ports there is little of interest on a coast, it is completely different with a land front, as in Russia and the east, N Africa and France Italy after landings had been made, the fighting on the ground and providing CAS drags the conflict down to ground level, higher altitudes covering for CAS operations.

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## pbehn (May 20, 2021)

P-39 Expert said:


> Agree with most of what you said. 1942 P-39 was way too heavy for the engine power available. *Dump the wing guns, nose armor plate* and IFF radio and a 7150lb P-39 would have done whatever the Captain asked. Endurance was actually over 3 hours which was better than single seat European fighters and enough to conduct operations in New Guinea that were mostly defensive in 1942.
> 
> It did make sense to design the new P-63 around the new engine, but it did not make sense to waste seven months in the middle of 1943 waiting on the airframe to be finished.


According to Wiki the Russians were still telling Bell to put more armour in and move the cannon forward in the P-63 in 1944. From start to finish Bell and yourself dont grasp that armour and other equipment werent there as ornamental and pretentious frippery.

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## FLYBOYJ (May 20, 2021)

_P-63A-8, SN 269261, was extensively tested at TsAGI in what was then the world's largest wind tunnel. Soviet input was significant. With the Soviet Union being the largest buyer of the aircraft, Bell was quick to implement their suggestions. The vast majority of the changes in the A sub-variants were a direct result of Soviet input, e.g.* increased pilot armor* and fuselage hardpoint on the A-5, underwing hardpoints and extra fuel tanks on the A-6, etc. The Soviet Union even experimented with ski landing gear for the P-63A-6, but this never reached production. Most significantly, Soviet input resulted in moving the main cannon forward, favorably changing the center of gravity, and increasing its ammo load from 30 to 58 rounds for the A-9 variant. The P-63 had an impressive roll rate, besting the Americans' P-47, P-40, and P-51—and the Japanese Navy's Kawanishi N1K2 Shiden-Kai fighter—with a rate of 110° per second at 275 mph (443 km/h). _

Dean, Francis H. _America's Hundred Thousand_. _pp. 410, 602_

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## P-39 Expert (May 20, 2021)

FLYBOYJ said:


> *The AAF was not going to dump the IFF in operational units*, so drop that, and depending on radio configuration, you cannot remove the armor plate in the nose as been shown over and over again! I have some more data coming to include Russian P-39 configurations.
> 
> And speaking of IFF - you have said that the Russians "removed" their IFFs. An IFF was a sensitive unit and even had a destruct system built into it. Do you have an accurate source to say the Russians were "removing" their IFFs or were P-39s were being delivered with IFFs not installed?!


We'll have to disagree on the nose armor. It certainly could be removed if other adjustments were made. The 20mm cannon was 140lbs lighter than the 37mm cannon and Bell made adjustments for that. The nose armor only weighed 71-100lbs. 

You don't need IFF if your base doesn't have radar. Port Moresby didn't get American radar until fall 1942. If you have not been detected on radar then you don't need to identify yourself as friendly. I'm only advocating removing the IFF sets in 1942. After then, when radar is available, the IFF radios, nose armor and 30cal wing machine guns can remain because the P-39 will have the uprated -85 engines. Again: Lighten the 1942 P-39D/F/K/L, not the more powerful 1943 M/N. 

I have read numerous times about the IFF radios being deleted by the Soviets along with the wing machine guns. They never deleted the nose armor that I am aware of.


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## pbehn (May 20, 2021)

P-39 Expert said:


> We'll have to disagree on the nose armor. .


You would even disagree with the Russians, maybe because you are posting on a forum, not actually fighting with it. From the very start Bell seem to have issues with giving their various clients what they wanted, North American, in part at least knew what their clients wanted better than they did themselves.

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## Glider (May 20, 2021)

P-39 Expert said:


> We'll have to disagree on the nose armor. It certainly could be removed if other adjustments were made. The 20mm cannon was 140lbs lighter than the 37mm cannon and Bell made adjustments for that. The nose armor only weighed 71-100lbs.


 You still have to explain why you would want to make your aircraft so vulnerable to anyone with an LMG


> You don't need IFF if your base doesn't have radar.


 That isn't how radar protection works. You need a number of radars to cover an area, Just having radar at your base is a pretty futile way of using it. For example no BOB base had its own radar


> Port Moresby didn't get American radar until fall 1942.


Hardly unexpected as this is only nine months after war broke out in the area and radar sets were in high demand all over the world.


> I have read numerous times about the IFF radios being deleted by the Soviets


 Total guess I admit, but how many US radars do you think the Russians had and what proportion of the contested area's do you think they covered? I would suggest not many and not much


> . They never deleted the nose armor that I am aware of.


 Why not do you think and why do you think your idea is so good?

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## FLYBOYJ (May 20, 2021)

P-39 Expert said:


> We'll have to disagree on the nose armor. It certainly could be removed if other adjustments were made. The 20mm cannon was 140lbs lighter than the 37mm cannon and Bell made adjustments for that. The nose armor only weighed 71-100lbs.



So what adjustments are you going to make? And when have we stared talking about the the 20mm cannon installation? 140 pounds lighter in the nose is going to make things worse!! I have showed you on this board several times that depending on the radio installation, you're not able to remove the nose armor.


P-39 Expert said:


> You don't need IFF if your base doesn't have radar. Port Moresby didn't get American radar until fall 1942. If you have not been detected on radar then you don't need to identify yourself as friendly. I'm only advocating removing the IFF sets in 1942.


Well then your 1942 P-39 will be without IFF but will have those huge radios in the empennage. You C/G will still be way aft and probably out of the envelope if you remove the nose armor


P-39 Expert said:


> After then, when radar is available, the IFF radios, nose armor and 30cal wing machine guns can remain because the P-39 will have the uprated -85 engines. Again: Lighten the 1942 P-39D/F/K/L, not the more powerful 1943 M/N.


 Agree on the wing machine guns but where are you installing the IFF? "Would have, could have should have"



P-39 Expert said:


> I have read numerous times about the IFF radios being deleted by the Soviets along with the wing machine guns. *They never deleted the nose armor that I am aware of*.


I'm not doubting you about the Soviets removing the IFF, it would seem funny why get them if you're just going to delete them.

Nose Armor...

Now with that said, a few new things.

On this wonderful site there is a Soviet P-39 flight manual and yes, it's in Russian. Since I don't read Russian, I rely on google translator. So here is the cutaway from the Soviet flight manual (in Russian) that's been copied in English many times.







This might be hard to read so you can go in the technical section and pull up the FREE PDF copy (such a deal). Anyway I will direct you to items 15 and 16. These items "радиоприемник" translate to "radio receiver" which means that some, maybe not all Soviet P-39s kept the radios in the rear and I believe they did use American radios (correct me if I'm wrong). If they were equipped with either the SCR-522 or the SCR-274 (or a Soviet unit), you're looking at close to 100 pounds if not more as a dynamotor was probably back there too.

Operationally I KNOW they used this configuration on P-39Qs. Now how do I know that? By the one fished out of the Russian Lake.






There were many photos taken of it;






And in the empennage, guess what was sitting there?











Now I can't tell if that unit is an SCR-274 or SCR-522 (or Russian), but they look awfully close. For those warbird maintainer folks on here, would you say those are at least 50 pound looking cathode-tube storage units? 

Photos courtesy Air & Space magazine for the photos and story - according to those folks this was an operational aircraft and had already seen action near Murmansk .

Oh - and here are a couple of photos that clearly show no radios installed behind the pilot, yes, older units.














I think you might recognize a few of these guys -

So as you say, the Soviets DID NOT remove the nose armor? Can you guess why?

Well My theory is as we know (an mentioned by you many times) they removed the wing guns, IFF (oh that pesky IFF) and maybe a few other things. Well I did a W&B calculation based on Greg's chart (once again thanks Greg!) and found that with the IFF, no wing guns and all ammo exhausted on 1/4 tank the C/G is at 135.9/ 30.19 % of MAC. Within limits but waaay aft.

Fully loaded, the same calculation - 134.2 - 28.07% of MAC

NOW - Remove the IFF at station 274 (I used 110 pounds) fly off your ammo and return with 1/4 gas and now that C/G is at *133.58 about 27-28% of MAC* (I/m almost ready to do spins!) A way better place to be in this aircraft.

NOW - Fully loaded? C/G *132.06* C/G Range? 130.1072 - 136.5584 Nice! Let's do spins!

It's quite obvious* WHY* the Soviets didn't remove the nose armor, especially if they were flying around with radios in the _*"empennage"*_

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## nuuumannn (May 20, 2021)

Peter Gunn said:


> the stars need to perfectly align.



Yup, nailed it. That they didn't for the p-39 and P-63 is more on the aircraft themselves rather than the conditions though, otherwise, there wouldn't have been better aircraft, which brings us to this next thing...



P-39 Expert said:


> P-39N was competitive with late 1942 P-38F/G, P-47B/C and P-51A. Yes it was.
> 
> The FW190A-6 vs P-39N graphs are graduated by altitude. Better climb and ceiling.



According to charts, which your entire argument is based around, not even real-world comparisons, which granted, between the Fw 190 and P-39 couldn't have happened in 1942 at any rate, but as you know, P-39 Expert, but steadfastly_ refuse_ to acknowledge and accept, charts present only a portion of aircraft performance and capability demonstration and _do not _reflect real-world conditions. You can present as many charts as you like saying the P-39 was 'superior' in climb or what have you compared to the P-51A etc, etc, but it isn't backed up by what actually happened nor the course of action the US military took in its aircraft procurement program. 

If it was so good, why did they give so many of them to the Russians and kept the P-38s, the P-47s and the P-51s, and the P-40s, which, taking Commonwealth service into consideration, outlived and saw greater proliferation than the P-39? Why did Bell build a replacement that required a bigger engine, better cooling, etc, but looked almost identical to it? _Because the P-39, over time could not match the expectations of the militaries that operated it. _Even the Russians, who did get much out of it were able to build better fighters that were a better match to the local conditions than it. 

Those other aircraft could. As has been said here already, the P-39 was just not capable of meeting the modern combat environment from 1943 onwards, after all, why would Bell build the P-63 if it was? Take the example of the Bf 109 and Spitfire, both saw remarkable transformation in their performance throughout the war and both remained relevant right through to the end because of the changes that were made to them, yet they predate the P-39 by a few years. The Mustang had a new engine installed which transformed its role in the war into an arguably war-winning one, the Fw 190, potent from the outset had new engines and armament fit that turned it into one of the most versatile and capable single-seat fighters of the war.

So, those charts you keep referring to as evidence of the P-39's greatness, against _all _the evidence that is being presented on this site alone, as well as the evidence that isn't, _do not _reflect how great the P-39 is and that collectively, we are just not seeing it, but rather _your_ inability to grasp the situation and your refusal to accept the evidence being presented to you.

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## GrauGeist (May 20, 2021)

For the love of God, stop with the obsession with the nose armor.
You CANNOT delete the nose armor because it was there to protect the gearbox.
We've been over this countless times - it was an integral part of the aircraft as much as the nose-gear was.

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## P-39 Expert (May 20, 2021)

FLYBOYJ said:


> So what adjustments are you going to make? And when have we stared talking about the the 20mm cannon installation? 140 pounds lighter in the nose is going to make things worse!! I have showed you on this board several times that depending on the radio installation, you're not able to remove the nose armor. *The cannon is just an example of how the plane could be ballasted when 140lbs is removed from the nose. *
> 
> Well then your 1942 P-39 will be without IFF but will have those huge radios in the empennage. You C/G will still be way aft and probably out of the envelope if you remove the nose armor
> Agree on the wing machine guns but where are you installing the IFF? "Would have, could have should have" *If the 110lb IFF is removed from the aft fuselage it will offset the removal of the 71-100lb nose armor.*
> ...


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## P-39 Expert (May 20, 2021)

GrauGeist said:


> For the love of God, stop with the obsession with the nose armor.
> You CANNOT delete the nose armor because it was there to protect the gearbox.
> We've been over this countless times - it was an integral part of the aircraft as much as the nose-gear was.


And as I have said countless times: No other fighters had armored gearboxes. None.


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## Dash119 (May 20, 2021)

P-39 Expert said:


> And as I have said countless times: No other fighters had armored gearboxes. None.


How many fighters had remote gearboxes? In almost every other case the gearbox was protected from the rear by that big chunk of armor we usually refer to as an engine...

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## FLYBOYJ (May 20, 2021)

P-39 Expert said:


> The cannon is just an example of how the plane could be ballasted when 140lbs is removed from the nose.





P-39 Expert said:


> If the 110lb IFF is removed from the aft fuselage it will offset the removal of the 71-100lb nose armor.



These are all "would have, could have, should have." And all this was not going to happen without a "customer" buying in. Why is that?



P-39 Expert said:


> Exactly my point, if you have nose armor then you need the radios in the tail. Without the nose armor the radios in the tail need to be removed or moved up behind the pilot for balance. The nose armor could be removed if other balance adjustments were made.


No, you once again you *MISSED THE POINT!!!* It's obvious for one reason or another the Soviets were flying P-39s WITH THE RADIOS IN THE TAIL. They may have had some aircraft configured with the radios behind the pilot but I'd stick my neck out to say that most of their Cobras kept the radios in the tail. With the armor in the nose *I HAVE CLEARLY SHOWN* the aircraft it sits in *a* *better W&B configuration, is no longer tail heavy and will have better spin and stall characteristics!!!*

*IMO THAT IS ONE OF THE REASONS WHY I BELIEVE THE SOVIETS HAD SUCCESS WITH THEM!!!!*

I've told you months ago that sometimes removing weight does not make the aircraft fly better, this is a perfect example!!!!

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## pbehn (May 20, 2021)

Divide the length of the eastern front by the number of fighters in service there, then divide the length of the reachable areas across the channel and the number of fighters. It is a completely different conflict.


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## GrauGeist (May 20, 2021)

P-39 Expert said:


> And as I have said countless times: No other fighters had armored gearboxes. None.


And as I have said before, no other production fighters were mid-engined with a driveshaft to the nose. None.

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## buffnut453 (May 20, 2021)



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## pbehn (May 20, 2021)

buffnut453 said:


> View attachment 624073


I think the armour in the nose twitched a bit.

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## GregP (May 20, 2021)

OK guys, I went into the museum today to work on the Grumman Mallard cowling and looked at both the P-39 and the P-63 while I was there.

There is a virtual plug in the P-63A behind the wing root training edge where the auxiliary supercharger goes and it has a cross member in it on which to mount the aux-stage supercharger. The area has plenty of room for the aux-stage A/C. The wing is moved back on the fuselage to balance the CG. The aux-stage supercharger is almost as wide as the engine itself. The P-39 does not have the plug and there is no room for the auxiliary-stage supercharger since the fuselage is more narrow than the auxiliary-stage supercharger itself.

A 2-stage Allison just will NOT fit. The engine compartment is virtually the same since both of them mounted the same engine block, but there is simply not room on the P-39 for the second stage and coupling. Granted, you could MAKE room, but you'd have to insert a plug to make room and then move the wing aft to make the CG possible ... and you'd have a P-63.

I have some pics of the P-63 and will come back here and insert same within a few days, but there is no way to mount a 2-stage Allison in the P-39 in a stock airframe. There is room for the engine, but not for the aux-stage S/C. If you disagree with that, I suggest you come look at them both in Chino, CA for yourself. If you come to see, let me know and I'll happily show you around so you see for yourself. If you are close then, by all means, PM me and I'll show you around. If you aren't close, you are welcome anyway but you'll be wasting your money if the trip is just to address this subject. The engine package for the 2-stage Allison just will not fit and, if it did, the resulting airplane would be out of CG aft without lead ballast in the nose or moving the wing aft to compensate.

I do NOT have too many pics of the P-39 because, to get the pics I need, I'd have to take off several panels from the P-39, and it is in a very good display and there is no real reason to do any disassembly when there is useful work to be done. There are enough P-39 pics available already. The cross-section of the P-39 fuselage just aft of the engine compartment narrows very quickly to the point where is simple to observe that the aux-stage will not fit. Casey Wright (currently working on the P-63) said that he has looked and said: 1) there are things in the way where the aux-stage would go, 2) there is no way to mount the aux stage, and 3) the fuselage is just too small where the aux stage would physically need to be.

Here is a P-39:





Look at the relative length of the nose in front of the wing versus the tail behind the trailing edge. The leading edge of the fin is about the same distance as the nose from the trailing edge. Note the insignia star has no bars and is behind the scoop just a small amount. If the insignia star HAD bars, the bars would extend ahead of the scoop rear edge. Note the engine exhaust manifolds stop just in front of the point where the wing trailing edge would intersect the fuselage. If it HAD an aux-stage supercharger, it would extend past the wing trailing edge to about the rear of the airscoop. The fuselage aft of the exhaust manifolds narrows quickly. Note if you extend the wing leading edge, it intersects the fuselage right about where the windscreen starts.






Here is a P-63. Note the insignia star has bars and the bars are still aft of the scoop rear edge. The tail is longer because there is more room behind the wing trailing edge and the engine exhaust manifolds are farther forward from the wing trailing edge. The aux supercharger stage would end about at the wing trailing edge. The fuselage at the end of the exhaust manifolds is about as wide as the engine compartment since the aux-stage goes in there. Note if you extend the wing leading edge to the fuselage it intersects right about the windscreen rear frame is. The wing has been moved aft about a foot or so from where it is on the P-39.

OK, here are some P-63 pics:






I apologize for the orientation, it's correct in my phone. I don't know how to rotate the pic in this forum. This is looking down into the "plug" at the rear of the engine bay, where the auxiliary supercharger would be if the engine were to be a 2-stage Allison. The engine installed is NOT a 2-stage, but CAN put out 1,600 hp if asked to do so. This empty space is NOT present in a P-39 and the rear bulkhead is up right against the aft end of the engine block.







Above is at least oriented correctly. You can see there is plenty of room behind the single-stage engine for the auxiliary-stage supercharger. This space is not present in the P-39.

All for now; cheers!

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## Dash119 (May 20, 2021)

Greg, that's all well and good but what about the nose armor and the IFF...

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## BiffF15 (May 20, 2021)

GregP said:


> OK guys, I went into the museum today to work on the Grumman Mallard cowling and looked at both the P-39 and the P-63 while I was there.
> 
> There is a virtual plug in the P-63A behind the wing root training edge where the auxiliary supercharger goes and it has a cross member in it on which to mount the aux-stage supercharger. The area has plenty of room for the aux-stage A/C. The wing is moved back on the fuselage to balance the CG. The aux-stage supercharger is almost as wide as the engine itself. The P-39 does not have the plug and there is no room for the auxiliary-stage supercharger since the fuselage is more narrow than the auxiliary-stage supercharger itself.
> 
> ...




Thanks Greg for taking the time, we appreciate it.

Hope it scores.

Cheers,
Biff

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## Juha3 (May 20, 2021)

Hello Nuuumannn
the fact is that Soviets demanded more Spitfires and P-39s and asked why Allies sent Hurricanes and P-40s instead of Spitfires and P-39s which they wanted. They got 10 very early Mustangs and appr. 200 P-47Ds. They don't like them and simply did not understand what to do with "monster" size P-47s, in the end Naval Aviation used them as fighter bombers very late of the war or just after the war. They definitely did not want more of them.
Three of the five top Soviet aces (Grigori Rechkalov, Nikolai Gulaev and Dmitri Glinka) got most of their kills while flying P-39s and Rechkalov and D. Glinka ended the war in May 1945 still flying P-39s with Guards units operating inside Germany. Gulaev was badly wounded in Aug 44 while flying P-39 with 129 GIAP. Stalin asked more P-39s and Spitfires, not P-40s and Hurricanes. And Valentine tanks not Churchills, another thing what put British wondering reason why.
Most of their fighters were rather small with short range and were low- and medium altitude fighters like P-39s and had centrally mounted armament. So P-39 suited their tactical thinking and the environment on the Eastern Front.

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## GregP (May 20, 2021)

Hi Dash 119,

The nose armor, for some reason, seems to have a life of its own. I'm still not sure why.

We have shot it several times and it refuses to die. I was thinking of asking my congressman to introduce a bill banning any mention of nose armor in public without a mask on. But the weight of the documentation would be more than the nose armor itself, so the exercise would seem to be full of greenhouse gases and thus would not be carbon-neutral.

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## Juha3 (May 20, 2021)

FLYBOYJ said:


> ...
> 
> View attachment 624071
> 
> I think you might recognize a few of these guys -...



IMHO Klubov, Rechkalov, Trud and Boris Glinka

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## FLYBOYJ (May 20, 2021)

GregP said:


> OK guys, I went into the museum today to work on the Grumman Mallard cowling and looked at both the P-39 and the P-63 while I was there.
> 
> There is a virtual plug in the P-63A behind the wing root training edge where the auxiliary supercharger goes and it has a cross member in it on which to mount the aux-stage supercharger. The area has plenty of room for the aux-stage A/C. The wing is moved back on the fuselage to balance the CG. The aux-stage supercharger is almost as wide as the engine itself. The P-39 does not have the plug and there is no room for the auxiliary-stage supercharger since the fuselage is more narrow than the auxiliary-stage supercharger itself.
> 
> ...



Thanks for doing this Greg. Question for one of the pilots (Steve H?) The shelf behind the pilot, how hot does it get from the engine?


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## gumbyk (May 20, 2021)

FLYBOYJ said:


> Thanks for doing this Greg. Question for one of the pilots (Steve H?) The shelf behind the pilot, how hot does it get from the engine?


and how strong is it?

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## Thumpalumpacus (May 20, 2021)

FLYBOYJ said:


> Thanks for doing this Greg. Question for one of the pilots (Steve H?) The shelf behind the pilot, how hot does it get from the engine?



I'm no pilot, but as a guitarist who uses tube amps to amplify his instrument, I can say that they can be sensitive to heat, even the heat the amp itself generates. I would imagine that putting such a tube amp (and that's what a transmitter was, in that era) atop another heat-source will shorten tube life and increase unreliability.

How much in this case, I've got no idea. I'd want to know the temperature of the mounting deck, the ventilation designed to accommodate it, and the insulation involved.

Additionally, the capacitors will be prone to leakage when exposed to excess heat.

Neither of these issues are instakill issues in most cases, especially not with the maintenance those P-39 radios presumably received. But it can be an issue, and tube failure due to heat can happen very quickly when it does happen. I lost a power-tube on an amp a couple of years ago, the voltage bounced back to the output transformer, and killed the amp then-and-there.

My amps use tubes designed in that era and commonly used in radios of that era (6L6 and 12--7s). The amps I use are actually based off of radio designs from the 30s, with design mods to make a guitar sound smokin' loud. 

Tube-amplifier designs must, repeat must, take heat-generation and heat dissipation into account.

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## FLYBOYJ (May 20, 2021)

gumbyk said:


> and how strong is it?





Thumpalumpacus said:


> I'm no pilot, but as a guitarist who uses tube amps to amplify his instrument, I can say that they can be sensitive to heat, even the heat the amp itself generates. I would imagine that putting such a tube amp (and that's what a transmitter was, in that era) atop another heat-source will shorten tube life and increase unreliability.
> 
> How much in this case, I've got no idea. I'd want to know the temperature of the mounting deck, the ventilation designed to accommodate it, and the insulation involved.
> 
> ...



This why I'm thinking you didn't see anything mounted here in earlier models, and even though the flight manual indicates as a "radio" goes there, I believe this area was possibly strengthened in time or there was some other equipment mounted there (camera?). In either case I think it's not a place for ice cubes.

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## GrauGeist (May 20, 2021)

If I'm not mistaken, the transmitter and receiver were mounted in it's own compartment in the rear of the fuselage, just ahead of the horizontal stabilizer.


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## gumbyk (May 20, 2021)

GrauGeist said:


> If I'm not mistaken, the transmitter and receiver were mounted in it's own compartment in the rear of the fuselage, just ahead of the horizontal stabilizer.


somewhere it was nice and cool, away from vibration...

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## FLYBOYJ (May 20, 2021)

GrauGeist said:


> If I'm not mistaken, the transmitter and receiver were mounted in it's own compartment in the rear of the fuselage, just ahead of the horizontal stabilizer.



Exactly, or one was mounted behind the pilot (in later models) and another in the empennage along with that pesky IFF.


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## GrauGeist (May 20, 2021)

gumbyk said:


> somewhere it was nice and cool, away from vibration...


And it is, I just checked and the transmitter and receiver are at the rear of the fuselage, side by side in the compartment just before the tail-plane.
Also double-checked and there was not an "IFF transponder" in the tail - the equipment in the tail is the actual two-way communication system.

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## gumbyk (May 20, 2021)

GrauGeist said:


> And it is, I just checked and the transmitter and receiver are at the rear of the fuselage, side by side in the compartment just before the tail-plane.
> Also double-checked and there was not an "IFF transponder" in the tail - the equipment in the tail is the actual two-way communication system.


I also wonder if development of better vibration isolators allowed them to move radios forward. There are so many issues that people don't fully understand. It's not as simple as removing the radio and bolting it somewhere else.

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## FLYBOYJ (May 20, 2021)

GrauGeist said:


> And it is, I just checked and the transmitter and receiver are at the rear of the fuselage, side by side in the compartment just before the tail-plane.
> Also double-checked and there was not an "IFF transponder" in the tail - the equipment in the tail is the actual two-way communication system.


Correct, mentioned a few post back.

This is what is looked like, mind you this is a later unit;


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## FLYBOYJ (May 20, 2021)

According to the flight manuals, you would of had 2 models of radios 

SCR-274 Command Radio

*



*

Or the SCR-522





I think in many of the cutaways you're looking at the Transmitter/ Receiver in one case and the transponder unit sitting next to it.


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## GrauGeist (May 20, 2021)

In detailed cutaways, the radio compartment is just aft of the oil reservoir and ahead of the tail-plane, the access door being on the port side and the full width of the fuselage.
While not being all that large, it was packed full of equipment. Also, the antenna lead to the aerial ran through an access port just above the compartment door.

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## SaparotRob (May 20, 2021)

Are P-39's owned by collectors twiddled with so that they're easier to fly? There were issues that mil spec P-39's had. With military equipment removed, did the Groundhog become pleasant to fly or do these "sport" planes need tinkering?


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## GregP (May 20, 2021)

I'll ask one of the pilots soon, but an Allison V-1710 gets as hot as any engine, and the shelf would be very warm. 

If aluminum were any good as an insulator, they wouldn't make cookware out of it. I'd assume (before asking, that is) that the shelf will get plenty warm. However, it is possible it has asbestos insulation on the bottom and is, in fact, fairly cool. Again, I'll ask.

I would not think there would be a lot of engine vibration on the shelf itself. When breaking in freshly-overhauled Allisons, I have put my hand on the engine when it was running to warm up after startup, and it is pretty smooth. The vibration SHOULD come mostly from the propeller and driveshaft, and THAT vibration is felt throughout the entire aircraft, moreso in the nose than elsewhere. Just thinking out loud.

When I get a chance, I'll ask.

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## FLYBOYJ (May 20, 2021)

GrauGeist said:


> In detailed cutaways, the radio compartment is just aft of the oil reservoir and ahead of the tail-plane, the access door being on the port side and the full width of the fuselage.
> While not being all that large, it was packed full of equipment. Also, the antenna lead to the aerial ran through an access port just above the compartment door.


Yes, but at the same time I wouldn't trust those to be exact. As shown configuration of radio equipment will vary.


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## wuzak (May 20, 2021)

P-39 Expert said:


> Dump the wing guns, nose armor plate and IFF radio and a 7150lb P-39 would have done whatever the Captain asked.





P-39 Expert said:


> You don't need IFF if your base doesn't have radar. Port Moresby didn't get American radar until fall 1942. If you have not been detected on radar then you don't need to identify yourself as friendly. I'm only advocating removing the IFF sets in 1942. After then, when radar is available, the IFF radios, nose armor and 30cal wing machine guns can remain because the P-39 will have the uprated -85 engines. Again: Lighten the 1942 P-39D/F/K/L, not the more powerful 1943 M/N.



Did the USN have radar in 1942? Was it equipped with IFF?

Did the USN operate anywhere near where P-39 bases were in 1942?

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## Tkdog (May 21, 2021)

I think it should be enough for the P-39 that it was in some ways innovative and it served honorably with the Soviets. The work of the designers and the builders was realized by verifiable results. 

Now. Let’s do something useful like talk about the Australian Boomerang or post war 109’s with Merlin engines.

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## FLYBOYJ (May 21, 2021)

Tkdog said:


> Now. Let’s do something useful like talk about the Australian Boomerang or post war 109’s with Merlin engines.



Start a thread!


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## fubar57 (May 21, 2021)

Tkdog said:


> Now. Let’s do something useful like talk about the Australian Boomerang or post war 109’s with Merlin engines.



.....or Boomerangs with Merlin engines

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## Greg Boeser (May 21, 2021)

Why did it fail? I mean on paper it's a world beater. Faster than a P-40, better climb than a P-51, able to go toe to toe with the FW-190A-6. And yet, the USAAF chose to go a different way. The British discovered a host of problems with theirs and dumped them on the Russians, or gave them back to the US. Only one US pilot made ace in them and that was in the Pacific. Two P-39 equipped fighter groups sent to Europe were re-equipped with Spitfire Vs before deploying to North Africa. the P-39 Groups that did go to NA were badly mauled and had to be relegated to coastal and convoy patrol. P-39 units flying ground attack missions needed air cover provided by P-40s. The Russians loved them, but if you had the choice between an I-16 or a Guaranteed Lacquered Coffin and a P-39 what would you choose?

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## GrauGeist (May 21, 2021)

FLYBOYJ said:


> Yes, but at the same time I wouldn't trust those to be exact. As shown configuration of radio equipment will vary.


Here's a good diagram showing the compartment area.
Over time, the equipment combinations would change, of course - the compartment, however, would remain the same.


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## GregP (May 21, 2021)

You can talk about Boomerangs with Merlins as long as you leave nose armor out of it.

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## rednev (May 21, 2021)

GregP said:


> You can talk about Boomerangs with Merlins as long as you leave nose armor out of it.


 but but the boomerang had 1250 lb of nose armour

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## bada (May 21, 2021)

P-39 Expert said:


> Standard late 1942 P-39N compared with a contemporary FW190A-6. Pretty competitive. Plus P-39 was more maneuverable and had longer endurance.



hi!
Late42 would be a 190A4 or even still an A3 (if we talking operationnal aircraft)..
what do you mean by more maneuvrable?...cause you're talking here about the plane that had the best rollrate of WII, so maneuvrability being a generic term, if we don't put some definition into it, itmay mean something different to different people. Please explain your idea of maneuvrability.

Also, could you confirm the following:
P39N Standard (operationnal)GrossWeight : 8200Lbs
War emergency pressure for the 1710-85 :58Hg
Thanks.


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## P-39 Expert (May 21, 2021)

Dash119 said:


> How many fighters had remote gearboxes? In almost every other case the gearbox was protected from the rear by that big chunk of armor we usually refer to as an engine...


But the nose armor was in front of the gearbox.


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## P-39 Expert (May 21, 2021)

bada said:


> hi!
> Late42 would be a 190A4 or even still an A3 (if we talking operationnal aircraft).. *A4 and A6 performance were about the same.*
> what do you mean by more maneuvrable?...cause you're talking here about the plane that had the best rollrate of WII, so maneuvrability being a generic term, if we don't put some definition into it, itmay mean something different to different people. Please explain your idea of maneuvrability. * Better turn rate.*
> 
> ...


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## P-39 Expert (May 21, 2021)

Greg Boeser said:


> Why did it fail? I mean on paper it's a world beater. *Didn't exactly fail. Half the top Soviet aces flew the P-39 and loved it. *Faster than a P-40, better climb than a P-51, able to go toe to toe with the FW-190A-6. And yet, the USAAF chose to go a different way. The British discovered a host of problems with theirs and dumped them on the Russians, or gave them back to the US. *The host of problems (compass etc.) were problems with any brand new airplane and were all quickly solved on AAF planes. Biggest problem was excessive weight which the British specified during construction. A 7850lb P-400 wouldn't meet the contract performance specs drawn up when expected gross weight was 5500lbs. Also they no longer needed them since the BoB was over and there would be no German invasion. And this was a cash contract not under lend-lease so they didn't want to pay for them. *Only one US pilot made ace in them and that was in the Pacific. Two P-39 equipped fighter groups sent to Europe were re-equipped with Spitfire Vs before deploying to North Africa. *The actual planes didn't go, just the pilots. The planes were sent to the west coast. *the P-39 Groups that did go to NA were badly mauled and had to be relegated to coastal and convoy patrol. P-39 units flying ground attack missions needed air cover provided by P-40s. *Those P-39s were flying ground attack because they had the cannon. No contemporary P-40 was as fast or climbed as fast as a P-39.* The Russians loved them, but if you had the choice between an I-16 or a Guaranteed Lacquered Coffin and a P-39 what would you choose? *They also had Yaks and Laggs. The fact that half the top Soviet aces and lots of 20+ victory aces flew the P-39 speaks for itself, especially since they received less than 5000 P-39s. Over 30000 Yaks were produced.*


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## P-39 Expert (May 21, 2021)

GrauGeist said:


> In detailed cutaways, the radio compartment is just aft of the oil reservoir and ahead of the tail-plane, the access door being on the port side and the full width of the fuselage.
> While not being all that large, it was packed full of equipment. Also, the antenna lead to the aerial ran through an access port just above the compartment door.


True, but photos and pilot's manuals show that some P-39s had radios mounted above the engine.


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## pbehn (May 21, 2021)

P-39 Expert said:


> *The host of problems (compass etc.) were problems with any brand new airplane and were all quickly solved on AAF planes. Biggest problem was excessive weight which the British specified during construction. A 7850lb P-400 wouldn't meet the contract performance specs drawn up when expected gross weight was 5500lbs. Also they no longer needed them since the BoB was over and there would be no German invasion. And this was a cash contract not under lend-lease so they didn't want to pay for them.*


You cannot continue to post this, it just isnt true, and you have been told why it isnt true. What is the point of this groundhog style of debate? You give your statements a rest for a while then bring them back.

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## tyrodtom (May 21, 2021)

P-39 Expert said:


> But the nose armor was in front of the gearbox.



I don't see your point.
If you're going to have armor you should position it so you can protect as much as possible.


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## DerAdlerIstGelandet (May 21, 2021)



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## glennasher (May 21, 2021)

You folks are waaaaaayyy more patient than I am. This whole argument is the definition of futility. Best of luck to your attempts to educate those who cannot be educated, due to the inability to absorb new information or information that contradicts a deeply infested idea.

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## Thumpalumpacus (May 21, 2021)

P-39 Expert said:


> *And this was a cash contract not under lend-lease so they didn't want to pay for them.*



There you go.

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## buffnut453 (May 21, 2021)

The gearbox was protected from behind by the engine, engine armour, pilot armour, and the contents of the nose gun bay. It didn’t need armour behind. 

As for the “Brits didn’t want to pay” bleat, thats just entirely bogus. Once again, I challenge P-39 Ex-Spurt to provide one shred of evidence for this assertion.

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## pbehn (May 21, 2021)

buffnut453 said:


> The gearbox was protected from behind by the engine, engine armour, pilot armour, and the contents of the nose gun bay. It didn’t need armour behind.
> 
> As for the “Brits didn’t want to pay” bleat, thats just entirely bogus. Once again, I challenge P-39 Ex-Spurt to provide one shred of evidence for this assertion.


This was one of his first assertions when he first joined, it is impossible to post anything new or that hasnt been posted before, it is impossible to use a forum search because there are thousands of posts discussing the P-39. When used by the British it was almost permanently grounded for modifications, only four were ever ready for combat and they did two missions, five were lost in accidents and I believe 2 pilots killed. In foreign hands the P-39 and Mustang MkI were contemporaries starting in service around May 1942.


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## SaparotRob (May 21, 2021)

Given that May, 1942 time, how did the Mustang MkI compare to the P-39? Obviously more favorably but was it in anyway close?


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## pbehn (May 21, 2021)

SaparotRob said:


> Given that May, 1942 time, how did the Mustang MkI compare to the P-39? Obviously more favorably but was it in anyway close?


The Mustang Mk I was in service until the end of the war with the RAF and they would have taken more. Altitude performance restricted what it could be used for, but there were still plenty of uses for it. The P-39s the British got should be described as pre production models, they just werent sorted at all, the Mustang Mk Is had some small issues when introduced, nothing like the problems with the P-39.

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## FLYBOYJ (May 21, 2021)

GrauGeist said:


> Here's a good diagram showing the compartment area.
> Over time, the equipment combinations would change, of course - the compartment, however, would remain the same.
> 
> View attachment 624081


Agree - that area was specifically designed to hold the radios - it's what went in there that was subject to change.

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## wuzak (May 21, 2021)

P-39 Expert said:


> *Biggest problem was excessive weight which the British specified during construction. A 7850lb P-400 wouldn't meet the contract performance specs drawn up when expected gross weight was 5500lbs.*




Was there ever a P-39 with a gross weight of 5,500lb? Not sure that any of the prototypes even reached that mark.

All your arguments for throwing away armour, IFF, moving radios, ditching guns, etc, only brings the weight down to 7,150lb to 7,250lb according to your estimations. What happened to the other 1,600+lb?

Perhaps if you throw out all the armour, all the guns and ammo you may get close. But what use is that?

Also, since you are arguing that the British should have had the P-39 without the "extra weight", the IFF should definitely stay. Because the British had radar and their aircraft had IFF.

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## Peter Gunn (May 21, 2021)

SaparotRob said:


> Given that May, 1942 time, how did the Mustang MkI compare to the P-39? Obviously more favorably but was it in anyway close?


Also the Mustang Mk I with the Allison was EXTREMELY fast at low altitude, drgondog can give you hard data but I believe they could knock down over 400MPH under 5,000 ft, faster than either the P-51B or D.

Basically speeds the P-39 could only dream about but not touch, hence its use as a recce a/c.

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## Peter Gunn (May 21, 2021)

Waaaaaiiit... did this thread's name change?

I call shenanigans...

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## buffnut453 (May 21, 2021)

There are so many P-39 threads that I simply can't keep up. I think I'm suffering from a kind of mania where I can't stop myself from checking in the vain hope that there's actually some new material or perspectives. I'm almost always disappointed.

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## FLYBOYJ (May 21, 2021)

wuzak said:


> Was there ever a P-39 with a gross weight of 5,500lb? Not sure that any of the prototypes even reached that mark.
> 
> All your arguments for throwing away armour, IFF, moving radios, ditching guns, etc, only brings the weight down to 7,150lb to 7,250lb according to your estimations. What happened to the other 1,600+lb?
> 
> ...



According to Greg's W&B calculator, if you removed all armor and guns and gunsight (what use is the gunsight without guns, right?) The weight comes down to 5,684 empty, 6,489 with fuel and oil

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## DerAdlerIstGelandet (May 21, 2021)

buffnut453 said:


> There are so many P-39 threads that I simply can't keep up. I think I'm suffering from a kind of mania where I can't stop myself from checking in the vain hope that there's actually some new material or perspectives. I'm almost always disappointed.



And I am getting sick and tired of every thread being hijacked because of a P-39 fetish.

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## wuzak (May 21, 2021)

P-39 Expert said:


> *Also they no longer needed them since the BoB was over and there would be no German invasion. And this was a cash contract not under lend-lease so they didn't want to pay for them.*



Since the Airacobra I didn't even start flight testing until April 1941 in the USA, I'm not sure how the BoB was relevant to the decision to keep or not keep the ordered aircraft.

From Airacobra I for RAF, P-400



> No. 601 Squadron pilots found numerous flaws and weaknesses during their initial work-up with the the Airacobra. Some of them were a question of improving operational efficiency and pilot comfort, but others were considered essential to make the aircraft operational. Numerous modifications were made in the field in an attempt to make the aircraft suitable for combat. A master valve was introduced to allow oxygen to be turned on from the cockpit. The gunsight was modified to improve forward visibility. Changes to the ammunition tanks for the wing guns were made. Modifications were made to the cockpit harness release in order to simplify the operation.* The IFF (Identification, Friend or Foe) set was removed from behind the pilot, where it obstructed aft view*. A throttle control quadrant friction damper was introduced.



One wonders if the IFF set behind the pilot impaired rear view, why would the AAF or Russians put a radio set there?




> The Airacobra was considered to be very suitable for low altitude operations because of the excellent view and controllability, and it was fully maneuverable at speeds above 160 mph. It was not difficult to fly at night, but the exhaust flames could be seen by another aircraft flying three miles to the rear. The flash from the nose guns was blinding, and could cause the pilot to lose not only his target but also his night vision. Firing of the nose guns caused the buildup of carbon monoxide contamination in the cockpit, and this could reach a lethal level very quickly. The guns were fairly inaccessible, and maintenance was troublesome.





> In spite of the problems with the compass and the need for flame dampers for the exhaust and flash suppressors for the nose guns, the RAF concluded that the Airacobra would make an excellent day fighter at altitudes below 20,000 feet and was well suited for the ground-attack role. However, before these plans could be implemented, *a decision was made to divert the bulk of the British Airacobra contract to Russia*.



Who made that decision? The British, the Americans, or was it a mutual decision?

Now, British P-39s had the 4 0.303" lmgs in the wings, which added weight, but they also had the lighter 20mm Hispano in the nose. I don't know the weights of these various things, so how much extra/less weight did the Airacobra I have in guns and ammo vs the P-39C, on which it was based?

Baugher does not mention that there was any additional armour in the Airacobra I.


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## Peter Gunn (May 21, 2021)

FLYBOYJ said:


> According to Greg's W&B calculator, if you removed all armor and guns and gunsight (what use is the gunsight without guns, right?) The weight comes down to 5,684 empty, 6,489 with fuel and oil


Not to put too fine a point on it but uh... where's this 5,500lb empty weight P-39 Expert keeps coming up with?

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## wuzak (May 21, 2021)

FLYBOYJ said:


> According to Greg's W&B calculator, if you removed all armor and guns and gunsight (what use is the gunsight without guns, right?) The weight comes down to 5,684 empty, 6,489 with fuel and oil



It is not surprising that the performance estimates of the P-39 at 5,500lb was not reflected in reality!

And from Baugher's site again:



> Unfortunately, Bell's glossy advertising brochures did not distinguish between the performance of a lightly-loaded, unarmed, highly-polished experimental prototype and a production fighter heavily-loaded with military equipment and armament, and the British were to rue the day that they ever looked at an Airacobra.

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## wuzak (May 21, 2021)

Peter Gunn said:


> Not to put too fine a point on it but uh... where's this 5,500lb empty weight P-39 Expert keeps coming up with?



I think that was the weight that the original XP-39 was supposed to have, but never did.

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## FLYBOYJ (May 21, 2021)

DerAdlerIstGelandet said:


> And I am getting sick and tired of every thread being hijacked because of a P-39 fetish.


Yep - I think one thread is good enough for Groundhog's Day!

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## FLYBOYJ (May 21, 2021)

wuzak said:


> It is not surprising that the performance estimates of the P-39 at 5,500lb was not reflected in reality!



Oh - I forgot, Take away ALL the radios AND the *IFF *and you're down to about 5384 empty, 6189 with fuel and oil.

So the 5,500 pound claim can be made with no guns, no armor, no radios and no fuel!

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## pbehn (May 21, 2021)

FLYBOYJ said:


> Oh - I forgot, Take away ALL the radios AND the *IFF *and you're down to about 5384 empty, 6189 with fuel and oil.
> 
> So the 5,500 pound claim can be made with no guns, no armor, no radios and no fuel!


I can understand the need for some fuel, as long as no one gets carried away, but surely you dont need much oil?

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## GrauGeist (May 21, 2021)

The only P-39 that was close to 5,000 pounds empty (but still equipped) wasn't even a P-39, it was the navy's XFL-1.

And it had nose armor...


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## DerAdlerIstGelandet (May 21, 2021)

FLYBOYJ said:


> Yep - I think one thread is good enough for Groundhog's Day!
> 
> View attachment 624125



Yeah just merge all of the P-39 threads into this one. It’s easier to ignore just one thread. Of course, as moderators we do not have the luxury of ignoring it.

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## DerAdlerIstGelandet (May 21, 2021)

All P-39 discussion is now to be conducted in this thread, and this thread alone.

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## pbehn (May 21, 2021)

GrauGeist said:


> And it had nose armor...


Then I conclude that it was noted early on that the P-39 had CoG issues and the weight to solve the issue was added as armour.


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## glennasher (May 21, 2021)

FLYBOYJ said:


> Oh - I forgot, Take away ALL the radios AND the *IFF *and you're down to about 5384 empty, 6189 with fuel and oil.
> 
> So the 5,500 pound claim can be made with no guns, no armor, no radios and no fuel!





So, a lawn ornament, then?

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## SaparotRob (May 21, 2021)

With regard to the answers from pbehn and Peter Gunn, why would one want to divert engines or better engines to the inferior airframe?


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## Peter Gunn (May 21, 2021)

SaparotRob said:


> With regard to the answers from pbehn and Peter Gunn, why would one want to divert engines or better engines to the inferior airframe?


*HERETIC!!!* Why would you bring logic into this discussion?

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## Shortround6 (May 21, 2021)

Now if we take out the large front teeth and streamline the nostrils a bit...................................................................................

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## GregP (May 21, 2021)

I went back to page 62, after finding that the thread name was changed, and put in a couple of pics of the P-63A engine compartment. Just FYI.

I compliment the moderators in consolidating the P-39 comments into this thread. Now we can simply ignore it going forward if we like. I like that option. 

Cheers.

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## GrauGeist (May 21, 2021)

pbehn said:


> Then I conclude that it was noted early on that the P-39 had CoG issues and the weight to solve the issue was added as armour.


The XFL didn't have the 37mm (though it could) but instead, either a 20mm or .50MG and interestingly enough, it was a conventional gear layout (tail dragger) as the nose-gear was eliminated.
So there was all sorts of CoG shuffling going on.

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## vikingBerserker (May 21, 2021)

Who keeps deleting my "P-39 vs F-35" thread????????

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## Marcel (May 21, 2021)

buffnut453 said:


> There are so many P-39 threads that I simply can't keep up.


Yeah, it even made me change my title.

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## GrauGeist (May 21, 2021)

And for the record, this was the only Cobra that Bell made, that was a true winner...

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## Marcel (May 21, 2021)

I was wondering if the P39 could have done the first flight better than the Wright Flyer I?

And when will Singapore Airlines replace it’s A380 fleet with a bunch of re-engined P39s?


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## DerAdlerIstGelandet (May 21, 2021)

GregP said:


> I went back to page 62, after finding that the thread name was changed, and put in a couple of pics of the P-63A engine compartment. Just FYI.
> 
> I compliment the moderators in consolidating the P-39 comments into this thread. Now we can simply ignore it going forward if we like. I like that option.
> 
> Cheers.



It may have screwed up the order of things, but I will be honest I don’t care. There is no need for multiple P-39 threads all saying the same repeated stuff over.

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## DerAdlerIstGelandet (May 21, 2021)

Thread title updated to a more accurate one.

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## fubar57 (May 21, 2021)

Website updated to a more accurate one...https://p-39groundhog ad nauseam/forum/

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## P-39 Expert (May 21, 2021)

GregP said:


> OK guys, I went into the museum today to work on the Grumman Mallard cowling and looked at both the P-39 and the P-63 while I was there.
> 
> There is a virtual plug in the P-63A behind the wing root training edge where the auxiliary supercharger goes and it has a cross member in it on which to mount the aux-stage supercharger. The area has plenty of room for the aux-stage A/C. The wing is moved back on the fuselage to balance the CG. The aux-stage supercharger is almost as wide as the engine itself. The P-39 does not have the plug and there is no room for the auxiliary-stage supercharger since the fuselage is more narrow than the auxiliary-stage supercharger itself.
> 
> ...


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## special ed (May 21, 2021)

I have.

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## Thumpalumpacus (May 21, 2021)

DerAdlerIstGelandet said:


> It may have screwed up the order of things, but I will be honest I don’t care. There is no need for multiple P-39 threads all saying the same repeated stuff over.



C'mon now. We need a thread on how a P-39 could do long range escort; we need a thread on how the P-39 would have foiled Pearl Harbor. We need a thread on how the P-39 saved Cairo from Rommel, how it saved Nimitz at Midway, and how it saved GMC when the Great Recession hit in 2009.

Whether I've cleared the statute of limitations for how it helped me rid myself of those pesky spam-callers or not may determine whether I start a thread about its potency in that theater of action. I can only say that the 37mm nose cannon shoots 30 rounds of Spam.


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## P-39 Expert (May 21, 2021)

GregP said:


> OK guys, I went into the museum today to work on the Grumman Mallard cowling and looked at both the P-39 and the P-63 while I was there.
> 
> There is a virtual plug in the P-63A behind the wing root training edge where the auxiliary supercharger goes and it has a cross member in it on which to mount the aux-stage supercharger. The area has plenty of room for the aux-stage A/C. The wing is moved back on the fuselage to balance the CG. The aux-stage supercharger is almost as wide as the engine itself. The P-39 does not have the plug and there is no room for the auxiliary-stage supercharger since the fuselage is more narrow than the auxiliary-stage supercharger itself.
> 
> ...


Man I appreciate all the work you have put into this, but I must respectfully disagree with you. The aux stage SC on the P-63 was in that area just in front of the radio mast in your P-63 photo above. On your P-39 photo above that radio mast (coincidentally) marks the exact same spot, the location of the bulkhead that separates the aux SC from the oil tank. The bulkheads on both planes are exactly the same distance from the front edge of the engine compartment. Both compartments are exactly the same size on each plane. Now some items in the P-39 would need to be moved, mainly the coolant tank, but if the aux SC fit in the P-63 than it would have to fit in the P-39. I have posted Bell drawings that verify this. 

Also, the engine compartment does not get narrower until aft of that bulkhead marked by the radio masts. See page 6 of the attached P-39 Weights & Measurements below. The two longitudinal beams that make up the forward fuselage are parallel, they do not get narrower. You are looking aft, the end nearest you is the attachment to the remote reduction gear (where the nose armor is located) then moving aft is the armament bay (sloped area) followed by the cockpit floor followed by the engine bay (the see through part). The aux SC would be located behind/under the beams where they begin to angle back up. The top tip of those beams is mounted to the bulkhead that is just in front of the oil tank and forms the aft end of the engine compartment. As you can see those longitudinal beams run parallel, they do not get narrower. Same amount of room in both planes. If it fit into one it had to fit into the other.


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## buffnut453 (May 21, 2021)

A far greater quantity of spam has been expended in the various P-39 threads...indeed, the discussion is like a gatling gun which just keeps spinning and spinning....and spinning.


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## pbehn (May 21, 2021)

SaparotRob said:


> With regard to the answers from pbehn and Peter Gunn, why would one want to divert engines or better engines to the inferior airframe?


Well, not all air frames are the best. By definition there is only one top dog. The P-39 wasnt utter rubbish, it wasnt as good as it was advertised either. Much of the story is about events and logistics as it is about performance curves. By the time The RAF were flying the P-39 with 601 squadron Germany had invaded Russia. Churchill offered the P-39 to the Russians. In the short term the UK probably had more aircraft in crates ready to send than the USA had. In the long term, the P-39 was as good or better than aircraft the Russians had in service but not better than those the RAF already had or would get shortly. Since the P-39 used the Allison it didnt take engines used by the types in US service or projected for the future it didnt affect any part of USA long term plans

There see... not a chart orCoG discussion at all.

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## P-39 Expert (May 21, 2021)

wuzak said:


> Was there ever a P-39 with a gross weight of 5,500lb? Not sure that any of the prototypes even reached that mark. *My apology, I just looked it up and the exact weight is 5849lbs gross per the contract signed in Feb 1940. This weight was the basis for the 400mph estimates, aka P-400. Final gross weight after the British finished with it in 1941 was 7850lbs. Ordered before the BoB, completed in 1941 after the BoB.*
> 
> All your arguments for throwing away armour, IFF, moving radios, ditching guns, etc, only brings the weight down to 7,150lb to 7,250lb according to your estimations. What happened to the other 1,600+lb? *The 7150lb weight is for a P-39D without wing guns and the nose armor (AHT). *
> 
> ...


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## buffnut453 (May 21, 2021)

P-39 Expert said:


> Also, the engine compartment does not get narrower until aft of that bulkhead marked by the radio masts. See page 6 of the attached P-39 Weights & Measurements below. The two longitudinal beams that make up the forward fuselage are parallel, they do not get narrower.



You cannot say that with certainty unless you have width measurements for the relevant stations. Drawings and schematics are merely representations of reality. You need detailed measurements for bulkheads, to include radii for any curves etc.

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## FLYBOYJ (May 21, 2021)

P-39 Expert said:


> The P-39 in 1942 was used in the Pacific at Port Moresby which didn't have radar until late 1942. So IFF was useless until radar was installed.


 From what I'm seeing the P-39s that were based at Port Moresby didn't have IFF installed in them to begin with. If you have information that says otherwise, I'm all ears.


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## Thumpalumpacus (May 21, 2021)

One cannon and two .50s ain't really a suitable armament suite for 1942-43 in a plane that is struggling to keep up on performance parameters as well. Add in short range and limited altitude performance, meh. 

There's a reason it was passed over. That was that it didn't deliver on promise.

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## P-39 Expert (May 21, 2021)

FLYBOYJ said:


> From what I'm seeing the P-39s that were based at Port Moresby didn't have IFF installed in them to begin with. If you have information that says otherwise, I'm all ears.


Per AHT the P-39D models did not, the P-400, D-1, D-2, K and L did. The IFF sets may have been added later to the D.


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## pbehn (May 21, 2021)

P-39 Expert said:


> *I just looked it up and the exact weight is 5849lbs gross per the contract signed in Feb 1940. This weight was the basis for the 400mph estimates, aka P-400. Final gross weight after the British finished with it in 1941 was 7850lbs. Ordered before the BoB, completed in 1941 after the BoB.*


This is utterly preposterous, it wasnt "the British" that changed the requirements it was the war, armour was put in planes not designed for it all over the world. The Spitfire doubled in weight for all sorts of reasons. Show me a any protest from North American discussing the P-51 about fitting more fuel inside and outside, more guns, tail warning radar, making it a dive bomber etc etc etc.

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## FLYBOYJ (May 21, 2021)

P-39 Expert said:


> Per AHT the P-39D models did not, the P-400, D-1, D-2, K and L did. The IFF sets may have been added later to the D.


Well it's kind of funny because IFF units were classified equipment and as mentioned several times had a destruct system built into them should a crash insure and the pilot survive. I believe in the emergency procedures in one of the P-39 flight manuals mentions activating the system if the aircraft was ever downed, so with that said I doubt that any P-39 or P-400 flying around Port Moresby had an IFF unit installed if no radar was available.


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## P-39 Expert (May 21, 2021)

Thumpalumpacus said:


> One cannon and two .50s ain't really a suitable armament suite for 1942-43 in a plane that is struggling to keep up on performance parameters as well. Add in short range and limited altitude performance, meh.
> 
> There's a reason it was passed over. That was that it didn't deliver on promise.


The AAF and Navy both were moving to 4 .50cal MGs (about 600lbs with ammo) as was installed in the P-51A/B/C , the FM2 Wildcat and the F8F Bearcat. The Navy evaluated the 20mm cannon as being worth three 50cal machine guns and AHT says the 37mm cannon was equivalent to the 20mm. Add the two 50cal nose guns, reduce their fire about 25% for synchronization loss and they are worth about 1.5 50cal guns. So the cannon and two synchronized 50s (400-575lbs) were equivalent to 4.5 50cal MGs. Plus centerline fire. Plus the exploding shell. Pretty potent armament. If you want you can have 10 50cal MGs but that will cause a severe weight penalty. It was all about the weight.

The 1943 P-39s with the -85 engines were fully the equal of the F4U-1, F6F, FW190A, Me109G, Typhoon and superior to the A6M and Ki-43 both in speed, climb and altitude performance. I can post the graphs again for you if you want.

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## P-39 Expert (May 21, 2021)

FLYBOYJ said:


> Well it's kind of funny because IFF units were classified equipment and as mentioned several times had a destruct system built into them should a crash insure and the pilot survive. I believe in the emergency procedures in one of the P-39 flight manuals mentions activating the system if the aircraft was ever downed, so with that said I doubt that any P-39 or P-400 flying around Port Moresby had an IFF unit installed if no radar was available.


The self destruct system was set to destroy the IFF radio in the event of a crash so that it wouldn't fall into enemy hands. If it was set incorrectly it would explode when the cockpit door was slammed shut.  With no radar the IFF sets should have been removed and stored until radar was installed. I don't know if they were or not.


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## FLYBOYJ (May 21, 2021)

P-39 Expert said:


> The 1943 P-39s with the -85 engines were fully the equal of the F4U-1, F6F...


 Can it land on a carrier and did it have the range???

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## P-39 Expert (May 21, 2021)

pbehn said:


> This is utterly preposterous, it wasnt "the British" that changed the requirements it was the war, armour was put in planes not designed for it all over the world. The Spitfire doubled in weight for all sorts of reasons. Show me a any protest from North American discussing the P-51 about fitting more fuel inside and outside, more guns, tail warning radar, making it a dive bomber etc etc etc.


It was most certainly the British who changed the requirements, it was their production contract and it was amended more than once. They signed the initial contract without armor plate and added it during the construction process as they realized it was needed.


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## P-39 Expert (May 21, 2021)

FLYBOYJ said:


> Can it land on a carrier and did it have the range???


No it couldn't land on a carrier, but then neither could the F4U-1. And range was equivalent to either the Navy fighters.


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## pbehn (May 21, 2021)

P-39 Expert said:


> The AAF and Navy both were moving to 4 .50cal MGs (about 600lbs with ammo) as was installed in the P-51A/B/C , the FM2 Wildcat and the F8F Bearcat. The Navy evaluated the 20mm cannon as being worth three 50cal machine guns and AHT says the 37mm cannon was equivalent to the 20mm. Add the two 50cal nose guns, reduce their fire about 25% for synchronization loss and they are worth about 1.5 50cal guns. So the cannon and two synchronized 50s (400-575lbs) were equivalent to 4.5 50cal MGs. Plus centerline fire. Plus the exploding shell. Pretty potent armament. If you want you can have 10 50cal MGs but that will cause a severe weight penalty. It was all about the weight.
> 
> The 1943 P-39s with the -85 engines were fully the equal of the F4U-1, F6F, FW190A, Me109G, *Typhoon* and superior to the A6M and Ki-43 both in speed, climb and altitude performance. I can post the graphs again for you if you want.


No they werent, by the end of 1943 the Typhoon was a fighter bomber, and was carrying a massive amount of extra internal armour in addition to being rock steady at 400MPH. The Typhoon as an interceptor ended the Fw 190 tip and run raids, could the P-39 do that? It eventually dropped bombs fired rockets and when it had dont that was still a 4x 20mm cannon armed fighter that could ruin your whole day could the P-39 do that?

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## fubar57 (May 21, 2021)

P-39 Expert said:


> No it couldn't land on a carrier, but then neither could the F4U-1. And range was equivalent to either the Navy fighters.



The British flew F4U-1s off of carriers in Nov. '43

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## pbehn (May 21, 2021)

Winkle Brown landed and took off from carriers in a P-39 then used the plane as his own run about, there would be issues with it in operations, mainly range and not being very good at anything.

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## FLYBOYJ (May 21, 2021)

P-39 Expert said:


> The self destruct system was set to destroy the IFF radio in the event of a crash so that it wouldn't fall into enemy hands. If it was set incorrectly it would explode when the cockpit door was slammed shut.  With no radar the IFF sets should have been removed and stored until radar was installed. I don't know if they were or not.


I'll bet dollars to donuts there wasn't a P-39 or P-400 flying around the SWP (Port Moresby 1942) with an IFF installed so your argument about removal of these units is a mute point. 

So the only thing that YOU think "could have" hypothetically helped the P-39 in the SWP was the removal of the wing guns (I agree) and the removal of the GB armor. I clearly showed you by leaving it in the C/G moved up over 2 inches putting the C/G right in the middle of the envelope in both the loaded and empty configuration. 

Again - ask yourself way the Russians left it in???? At the end of the day this 70 pounds would not have made a difference, would not have made the P-39 any faster or more maneuverable but safer to fly - oh yea, with the radios in the tail no less!!!


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## FLYBOYJ (May 21, 2021)

P-39 Expert said:


> No it couldn't land on a carrier, but then neither could the F4U-1. And range was equivalent to either the Navy fighters.



Equivalent (in your opinion) - not better!!!


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## pbehn (May 21, 2021)

P-39 Expert said:


> It was most certainly the British who changed the requirements, it was their production contract and it was amended more than once. They signed the initial contract without armor plate and added it during the construction process as they realized it was needed.


No, they realised it wasnt in the contract, it was needed since before the Battle of Britain, armour and self sealing tanks were part of being a fighter from the battle of France, you are advocating allied pilots being in death traps that Zero pilots were, but the Zero had an excuse, it had phenomenal range.


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## P-39 Expert (May 21, 2021)

pbehn said:


> No they werent, by the end of 1943 the Typhoon was a fighter bomber, and was carrying a massive amount of extra internal armour in addition to being rock steady at 400MPH. The Typhoon as an interceptor ended the Fw 190 tip and run raids, could the P-39 do that? It eventually dropped bombs fired rockets and when it had dont that was still a 4x 20mm cannon armed fighter that could ruin your whole day could the P-39 do that?


Only reason the Typhoon was a fighter bomber was because it couldn't do interception at high altitude. P-39 was a beast at low altitude, go to wwiiaircraftperformance and compare them with the Typhoon. And one hit from a 37mm cannon will definitely ruin your day no matter what you are flying.


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## FLYBOYJ (May 21, 2021)

P-39 Expert said:


> Only reason the Typhoon was a fighter bomber was because it couldn't do interception at high altitude. P-39 was a beast at low altitude, go to wwiiaircraftperformance and compare them with the Typhoon. And one hit from a 37mm cannon will definitely ruin your day no matter what you are flying.


But wait, what happened to the lighter 20mm we were talking about yesterday? Now 120 lbs more in the nose is ok?

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## ThomasP (May 21, 2021)

re the IFF in early P-39s in the PTO.

The first IFF used by the US was the UK IFF 'Pipsqueak' or RC-96-A in US terms, which was basically just an intermittent broadcast circuit for the radio transmitter set. This sent out a predetermined pulse of abut 14 seconds, switched back to normal radio operation for a predetermined time, then sent out the 14 sec pulse again, etc. The frequency of the pulse was the same as the radar detecting it.

I know this was used with the SCR-522 VHF set (BC-608-A) fitted in the P-39 in the PTO. I have seen diagrams and weight lists.

I think it was also used in some of the early airframes fitted with the SCR-274 HF sets (BC-608-A & BC-616). I have seen weight lists but not any diagrams of the fit.

I have also read accounts about the US using 'Pipsqueak' in the PTO but I do not remember where or exactly why, other than to help not get shot down by US or Australian friendlies.

edit: deleted the "Mk I" part of "IFF Mk I", as the Mk I IFF was a different system. oops

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## pbehn (May 21, 2021)

P-39 Expert said:


> Only reason the Typhoon was a fighter bomber was because it couldn't do interception at high altitude. P-39 was a beast at low altitude, go to wwiiaircraftperformance and compare them with the Typhoon. And one hit from a 37mm cannon will definitely ruin your day no matter what you are flying.


So could the P-39 do it at high altitude? Your chances of hitting anything with one 37mm cannon are massively smaller than with 4x 20 mm cannon. Just face facts, the P-39 was the USAs Gloster Gladiator, it did a job until better stuff was available.

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## P-39 Expert (May 21, 2021)

FLYBOYJ said:


> But wait, what happened to the lighter 20mm we were talking about yesterday? Now 120 lbs more in the nose is ok?


The 20mm cannon was just an example to illustrate that Bell was able to balance the P-39/400 with either cannon in the nose even though one was 140lbs lighter than the other. Surely you know that, right?


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## P-39 Expert (May 21, 2021)

pbehn said:


> So could the P-39 do it at high altitude? Your chances of hitting anything with one 37mm cannon are massively smaller than with 4x 20 mm cannon. Just face facts, the P-39 was the USAs Gloster Gladiator, it did a job until better stuff was available.


Seriously? The Gladiator was a 250mph biplane.


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## Thumpalumpacus (May 21, 2021)

P-39 Expert said:


> The AAF and Navy both were moving to 4 .50cal MGs (about 600lbs with ammo) as was installed in the P-51A/B/C , the FM2 Wildcat and the F8F Bearcat. The Navy evaluated the 20mm cannon as being worth three 50cal machine guns and AHT says the 37mm cannon was equivalent to the 20mm. Add the two 50cal nose guns, reduce their fire about 25% for synchronization loss and they are worth about 1.5 50cal guns. So the cannon and two synchronized 50s (400-575lbs) were equivalent to 4.5 50cal MGs. Plus centerline fire. Plus the exploding shell. Pretty potent armament. If you want you can have 10 50cal MGs but that will cause a severe weight penalty. It was all about the weight.
> 
> The 1943 P-39s with the -85 engines were fully the equal of the F4U-1, F6F, FW190A, Me109G, Typhoon and superior to the A6M and Ki-43 both in speed, climb and altitude performance. I can post the graphs again for you if you want.



Actually, the USAAF had moved to six .50s in the -51, eight in the -47, four .50s and a cannon in the -38, and the Navy in 1943 had standardized on the F6F's six .50s, so I'm seeing a bit of underselling here on your part. Oh, and the F4U1 had six .50s as well.

If you're pulling guns, armor, and the goddamned radio to get climb or maneuverability, your plane probably ain't cutting the mustard.

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## pbehn (May 21, 2021)

P-39 Expert said:


> Seriously? The Gladiator was a 250mph biplane.


Yes seriously. Performance in numbers is immaterial, the Gladiator saw service in the Battle of France, Battle of Britain, Malta and North Africa and was replaced ASAP by better aircraft. It achieved "air superiority" over the Italians in Ethiopia in June 1941.

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## Glider (May 21, 2021)

P-39 Expert said:


> Only reason the Typhoon was a fighter bomber was because it couldn't do interception at high altitude. P-39 was a beast at low altitude, go to wwiiaircraftperformance and compare them with the Typhoon. And one hit from a 37mm cannon will definitely ruin your day no matter what you are flying.



No one would deny that there was a disappointment in the altitude performance of the Typhoon, but your statement _Only reason the Typhoon was a fighter bomber was because it couldn't do interception at high altitude_ is as ever, far too simplistic.

The RAF had the Spitfire as an interceptor which was always very effective at altitude. What the Typhoon had in its favour was the following:-
a) an exceptional low level performance at low / medium altitude Reaching approx 400mph at 8,800ft 415mph at 20,000ft, a lot faster than a Spitfire
b) The capability of carrying very heavy payload of up to 2,000lb plus of course 4 x 20mm
c) It was well armoured with pilot eventually sitting in almost a bath of armour

Lets look at those parameters on the P39
a) P39N 398 mph at 9,700ft 389 mph at 16,100ft Both are very quick and its likely that the inevitable differences you get in mass production would make them very similar.
b) I am not sure what the GA capability of the P39 is but it seems to be in the area of 500lb of bombs which isn't even close to the capability of the Typhoon
c) Again I haven't seen anything that shows the P39 as having anything remotely close to the armour protection of the Typhoon 
Note the P39Q seems to have a worse performance

The RAF lacks a GA aircraft and the Typhoon had all the right attributes, that's why it was the RAF's premier GA aircraft.

Your comment about the effect of a hit by the 37 is, again overly simplistic. You are correct in that a hit would ruin anyone's day but compared to the 20mm Hispano II

37mm rof 150 rpm mv 2,000ft/min
20mm rof 600 rpm mv 2,700ft/min

You are far more likely to be hit by multiple 20mm rounds which would also ruin anyone's day

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## Thumpalumpacus (May 21, 2021)

P-39 Expert said:


> If it was set incorrectly it would explode when the cockpit door was slammed shut.



Sound like a great front-line aircraft to me.


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## pbehn (May 21, 2021)

Glider said:


> Your comment about the effect of a hit by the 37 is, again overly simplistic. You are correct in that a hit would ruin anyone's day but compared to the 20mm Hispano II
> 
> 37mm rof 150 rpm mv 2,000ft/min
> 20mm rof 600 rpm mv 2,700ft/min
> ...


Generally between 1 and 3 hits from a 20 mm cannon would take down an S/E aircraft, a Typhoon was firing 16 times as many shells per second.

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## Crimea_River (May 21, 2021)

I like beer.

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## fubar57 (May 21, 2021)



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## P-39 Expert (May 21, 2021)

Thumpalumpacus said:


> Actually, the USAAF had moved to six .50s in the -51, eight in the -47, four .50s and a cannon in the -38, and the Navy in 1943 had standardized on the F6F's six .50s, so I'm seeing a bit of underselling here on your part. Oh, and the F4U1 had six .50s as well.
> 
> If you're pulling guns, armor, and the goddamned radio to get climb or maneuverability, your plane probably ain't cutting the mustard.


The P-47, P-38, F6F and F4F all came out before the P-51B/C, FM2 or F8F, so the services were moving to 4 50calMGs. The P-51D went to six, but by then air superiority over Europe had been won and it didn't really matter. If a plane is too heavy it aint cutting the mustard as you say. If you can lighten it then it can cut the mustard.


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## Crimea_River (May 21, 2021)



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## P-39 Expert (May 21, 2021)

Glider said:


> No one would deny that there was a disappointment in the altitude performance of the Typhoon, but your statement _Only reason the Typhoon was a fighter bomber was because it couldn't do interception at high altitude_ is as ever, far too simplistic.
> 
> The RAF had the Spitfire as an interceptor which was always very effective at altitude. What the Typhoon had in its favour was the following:-
> a) an exceptional low level performance at low / medium altitude Reaching approx 400mph at 8,800ft 415mph at 20,000ft, a lot faster than a Spitfire
> ...


wwiiaircraftperformance.org shows the Typhoon to make 375mph at 10000ft and 395mph at 20000ft and climbed at 2000fpm at 20000ft. The P-39N was at least as fast and outclimbed the Typhoon by 600fpm at all altitudes.


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## pbehn (May 21, 2021)

P-39 Expert said:


> It was most certainly the British who changed the requirements, it was their production contract and it was amended more than once. They signed the initial contract without armor plate and added it during the construction process as they realized it was needed.


Yes, these things happen in a world war, the Hurricane had armour and self sealing tanks installed along with all sorts of radio gizmos and 4 cannon. It was a world war not a Reno handicap race.

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## FLYBOYJ (May 21, 2021)

P-39 Expert said:


> The 20mm cannon was just an example to illustrate that Bell was able to balance the P-39/400 with either cannon in the nose even though one was 140lbs lighter than the other. Surely you know that, right?


I do know that, but you continue to try to use issues like this to justify most of your arguments. And again, if you take weight out of the nose by installing a lighter cannon you’re making matters worse! If you want, I’ll do a weight balance calculation with a 20 mm cannon and remove the gear box armor.

*This tells me that the P-400 probably had ballast in the nose along with that (drumroll) gear box armor!*

BTW - You "balance" on a see-saw, you "balance" on a tight rope, you get an airplane in "Center of Gravity Range" or *C/G*.


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## FLYBOYJ (May 21, 2021)

ThomasP said:


> re the IFF in early P-39s in the PTO.
> 
> The first IFF used by the US was the UK IFF Mk I 'Pipsqueak' or RC-96-A in US terms, which was basically just an intermittent broadcast circuit for the radio transmitter set. This sent out a predetermined pulse of abut 14 seconds, switched back to normal radio operation for a predetermined time, then sent out the 14 sec pulse again, etc. The frequency of the pulse was the same as the radar detecting it.
> 
> ...


There are diagrams that show “radios“ in the tail and behind the pilot. If you have any other data or equipment/ weight lists that you could share, we’d really appreciate it!


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## Glider (May 21, 2021)

P-39 Expert said:


> wwiiaircraftperformance.org shows the Typhoon to make 375mph at 10000ft and 395mph at 20000ft and climbed at 2000fpm at 20000ft. The P-39N was at least as fast and outclimbed the Typhoon by 600fpm at all altitudes.



*From the web site you quoted*

*August 1943.*
Cleaning up.
The remaining cleaning up modifications are now on the production machine. (I think we can agree that this was the standard production version of the Typhoon for the war in Europe, post invasion)

These are(a) Exhaust shrouds.(b) Whip aerial(c) Sliding hood.
Tests at Gloster on a repaired aircraft with a whip aerial and sliding hood fitted have given the following level speeds corrected on the basis of A. & A.E.E. Res.170.
M.S. M.P.A 398 m.p.h. at 8,800ft F.S. M.P.A 417 m.p.h. at 20,500ft.

*Note* - I also notice that you don't disagree with my comments on the Payload carried by the Typhoon, its much better armour and general firepower.


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## Thumpalumpacus (May 21, 2021)

P-39 Expert said:


> The P-47, P-38, F6F and F4F all came out before the P-51B/C, FM2 or F8F, so the services were moving to 4 50calMGs. The P-51D went to six, but by then air superiority over Europe had been won and it didn't really matter. If a plane is too heavy it aint cutting the mustard as you say. If you can lighten it then it can cut the mustard.



You're doing some fine cherry-picking here. I'm not big on interrupting things, but by 1944 only the F8F was moving forward with 4x.50s

How many P-51B/C/Ds served in ETO, compared to _any_ model of P-39?

How many P-47C/Ds or P-38s served in ETO and SoWesPac compared to the P-39?

If only you'd held Hap Arnold's chair! If only your insight had rescued the Allies from the folly of building the P-47, P-38, and P-51 in mass numbers. Gosh, we might have won the war in the air.

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## Shortround6 (May 21, 2021)

P-39 Expert said:


> Only reason the Typhoon was a fighter bomber was because it couldn't do interception at high altitude. P-39 was a beast at low altitude, go to wwiiaircraftperformance and compare them with the Typhoon. And _one hit from a 37mm cannon will definitely ruin your day_ no matter what you are flying.



Quite right, a hit _assuming_ there is one will ruin your day. '
How good is your day if you are hit by 16 20mm shells? 
Difference in the rate of fire of the 37mm and four 20mm Hispano guns. 
The Hispano guns, being higher velocity, are easier to hit with. 

P-39s could NOT do interceptions at high altitude either. 

I am comparing the P-39M (nov 1942) to the Typhoon (Nov 1942) not seeing the Beast. 
P-39M does 345mph at 2750ft using 57in of Map and 322mph using military power. Typhoon does 349.5 at 2000ft and 357.5 at 4,000ft. using 7lbs of boost.

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## Shortround6 (May 21, 2021)

As to the four .50 cal thing. 

The need for six guns waxed and waned. Most gun histories don't give dates or at least not good ones. It was hard to figure out what the "planners" intended or hoped for a year or more down the road. 

The US .50 jumped from 600rpm (free firing with short belts and no G load) to about 800rpm in late 1940. The Americans very quickly started multiple projects to increase the rate of fire to 1200rpm. At least three different companies and some of them ran simultaneous projects and some ran sequential projects. The records show something like 15 (?) different model numbers. A batch of several thousand (10,000?) were built using a "T" number in late 1944/45 before it was standardized as the M3. The F8F may never have gotten the fast firing guns but the intent to use them cannot be ruled out. 
The programs suffered numerous failures in trying to meet the US desired standards of rate of fire, parts broken or jams per 1000 rounds fired and gun life (not barrel life). 
At any given moment a future fighter may have been intended to use four fast firing guns only to be let down by the gun development program/s.

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## Greg Boeser (May 21, 2021)

Thumpalumpacus said:


> One cannon and two .50s ain't really a suitable armament suite for 1942-43 in a plane that is struggling to keep up on performance parameters as well. Add in short range and limited altitude performance, meh.


Tell that to Messerschmitt, Yakovlev, Lavochkin, and company

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## Greg Boeser (May 21, 2021)

P-39 Expert said:


> No it couldn't land on a carrier, but then neither could the F4U-1. And range was equivalent to either the Navy fighters.


F4U-1s were landing on carriers from their inception. VF-17 was to be the fighter complement on board USS Bunker Hill (CV-17) but was pulled off when the carrier reached Hawaii. They flew from land bases because the Navy wanted to keep their fleet air wings standardized and Grumman was cranking out a lot of F6Fs. The RN was flying Corsairs from jeep carriers long before the USN decided to upgrade the fleet air wings in the face of kamikaze attacks. The F4U's speed advantage being a key consideration. VF-17 did a one off during the Navy's attack on Rabaul, 11 Nov 1943. Flying from their land base they flew CAP for the fleet, landed on the carriers to refuel and then flew another CAP before returning to their base. During this mission they engaged an enemy air attack as well as shot down enemy snoopers.

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## Thumpalumpacus (May 21, 2021)

Greg Boeser said:


> Tell that to Messerschmitt, Yakovlev, Lavochkin, and company



Tell that to Sakai & co.


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## Shortround6 (May 21, 2021)

Greg Boeser said:


> Tell that to Messerschmitt, Yakovlev, Lavochkin, and company




You have to look at the guns,

The Russian 12.7mm MG would fire at 800rpm or close to it when synchronized. The US .50 in the early planes was under 500 rpm in the cowl. Later ones might have been better? but not near 800rpm. Some authors say it neve got over 600rpm for a cowl gun. 
The Germans, once they got the MG 131 were firing at 900rpm per barrel. being electric primed it only lost about 10% of it's rate of fire when synchronized. A lot less powerful but you had around 50% higher rate of fire to make up for it.

Similar story for the 20mm guns through the prop. Not as powerful as the Hispano but higher rates of fire. 
The American 37mm was both low velocity and ssslllooooooww firing. Not a good combination for air to air gunnery. 

150rpm and 610m/s velocity.

German Mg 151/20 fired close to 700rpm and velocity was 700-785M/s depending on projectile. Gun in the 109 was free firing, guns in the wing roots of the 190 were synchronized. 

Russian 20mm ShVAk cannon fired at 700-800rpm and had a velocity of 750-790 m/s. 

a plane flying at 300mph is going to move 176ft between shots from the US cannon. 

I would also note the US combination has the worst mismatch by far of trajectory and time of flight of the three examples. You can pretty much kiss off any hope of long range gunnery hitting with both guns at the same time. This suited the Russians who preferred to get in close (perhaps because in many of their planes the guns sights were rather rudimentary?)


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## Greg Boeser (May 21, 2021)

Well, if you dumped the .50s for pulse cannon I think the P-39 would be unstoppable.

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## Shortround6 (May 21, 2021)

This plane was armed (or planned to be) with two .50s and two 37mm cannon. 
Part of the nose was supposed to tilt so both types of guns would hit in the same place at various ranges.


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## GrauGeist (May 21, 2021)

P-39 Expert said:


> No it couldn't land on a carrier, but then neither could the F4U-1. And range was equivalent to either the Navy fighters.


The range of the P-39 was half that of Navy fighters.
The F4U's range was 1,000 miles.
The F6F's range was 945 miles.
The F4F's range was 845 miles.
And even the SBD's range was 1,100 miles.
All these ranges are with internal fuel and combat loads - the ferry ranges were further.
And every single aircraft listed above operated from carriers during the war.

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## GrauGeist (May 21, 2021)

Greg Boeser said:


> Well, if you dumped the .50s for pulse cannon I think the P-39 would be unstoppable.


That is subject to debate...

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## wuzak (May 21, 2021)

FLYBOYJ said:


> I'll bet dollars to donuts there wasn't a P-39 or P-400 flying around the SWP (Port Moresby 1942) with an IFF installed so your argument about removal of these units is a mute point.



I don't think the experts in this thread will remain mute.

Though I expect you meant moot!

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## wuzak (May 21, 2021)

P-39 Expert said:


> *My apology, I just looked it up and the exact weight is 5849lbs gross per the contract signed in Feb 1940. This weight was the basis for the 400mph estimates, aka P-400. Final gross weight after the British finished with it in 1941 was 7850lbs. Ordered before the BoB, completed in 1941 after the BoB.*



I'm sure with contract revisions Bell would have revised their performance estimates?

Maybe Bell was still full of shit?




P-39 Expert said:


> *The 7150lb weight is for a P-39D without wing guns and the nose armor (AHT).*



Ah, the infamous nose armour. What would a thread be without it?




P-39 Expert said:


> *Yes the British specified an IFF radio and yes they did have radar. But they didn't use their P-400s. The P-39 in 1942 was used in the Pacific at Port Moresby which didn't have radar until late 1942. So IFF was useless until radar was installed. Any more exaggerations I can help you with? *



I am confused.

Are you reconfiguring the P-39D to be a better weapon of war, or for just one point of time at one location during the war?

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## wuzak (May 21, 2021)

Greg Boeser said:


> Well, if you dumped the .50s for pulse cannon I think the P-39 would be unstoppable.



Don't be silly.

The pulse cannons didn't exist, and still don't.


The remote gearbox surely allows for the installation of a 20mm Vulcan in the nose firing through the hub, instead of the 37mm.

Once that is installed we can confidently ditch the nose armour, wing guns and probably the cowl guns. With the ammo the P-39 could carry, the firing time will be down to 1s or less.


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## PAT303 (May 21, 2021)

While this thread and others like it involving members who cannot learn or accept facts are a lost course they do bring out the best information in the vain attempt to teach the unteachable, in that sense they do contribute to the forum.

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## FLYBOYJ (May 21, 2021)

wuzak said:


> I don't think the experts in this thread will remain mute.
> 
> Though I expect you meant moot!



I did LOL!

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## Shortround6 (May 21, 2021)

Greg Boeser said:


> Well, if you dumped the .50s for pulse cannon I think the P-39 would be unstoppable.



Everybody knows that disrupters are 3 times more effective than pulse cannon


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## Shortround6 (May 21, 2021)

"* I just looked it up and the exact weight is 5849lbs gross per the contract signed in Feb 1940. This weight was the basis for the 400mph estimates, aka P-400. Final gross weight after the British finished with it in 1941 was 7850lbs"*


Hmm, strangely enough, the P-39C went 5,070lbs empty, 7075lbs gross weight (combat) and 7300lbs max gross. They were ordered August 10th 1939. So, in Feb of 1940, 6 months later Bell is telling the British the plane will only weigh 5879lbs gross for combat? 
809lbs useful load? 
160lb pilot (including 20lb parachute) 
290lbs just for the .50 cal guns and ammo 
45lbs of oil (2 gallons for the gear box and only 4 gallons for the engine) 

Leaves us about 70 gallons of gasoline and no gun sight. 

There was absolutely no way Bell could have delivered a usable fighter aircraft even without armor or protected tanks with a gross weight of 5849lbs, regardless of what the British did.

On Sept 13th 1940 the USAAC ordered a bunch of P-39Ds and changed the contract for the 21st through 80th P-39C to P-39Ds with protection and wing guns. 
From Joe Baugher's website on the P-39D page. 
Weights: 5462 pounds empty, 7500 pounds gross, and 8200 pounds maximum takeoff. 

Want to tell us *in detail* just what those perfidious sons of Avalon specified in the P-400s that the US was not specifying in the P-39D?

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## Greg Boeser (May 22, 2021)

Shortround6 said:


> Everybody knows that disrupters are 3 times more effective than pulse cannon


True, but the Allison just doesn't produce the horsepower required, at least until the -85, and then only below 18000'


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## GregP (May 22, 2021)

Regarding post #1311:

I respect your right to disagree, P-39 Expert, but we have looked at the actual airplanes in the last two days and there is no room for the Aux-stage supercharger without modifications that make the P-39 into not a P-39. Everything that is in the way would have be moved rearward, exacerbating the already-rearward CG issue, and the Aux supercharger just will not quite fit.

As I stated above, you are welcome to come visit and look yourself. But I doubt anyone will be granted access to disassemble that particular P-39. Still, there is another one in the airport and you can see inside easily. Sorry, guy, it doesn't fit.

With that, I am done with P-39s in this thread and also unless and until someone wants to discuss something realistic about the airplane. There is nothing wrong with a P-39 that cannot be discussed as long as stay with the actual facts. One of the most unloved fighters in U.S. service in WWII doesn't suddenly turn into an overnight success 75 years after the fact, despite a Groundhog thread. 

Cheers.

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## FLYBOYJ (May 22, 2021)

GregP said:


> Regarding post #1311:
> 
> I respect your right to disagree, P-39 Expert, but we have looked at the actual airplanes in the last two days and there is no room for the Aux-stage supercharger without modifications that make the P-39 into not a P-39. Everything that is in the way would have be moved rearward, exacerbating the already-rearward CG issue, and the Aux supercharger just will not quite fit.
> 
> ...



This reminds me of my time at Lockheed when I would find issues on an aircraft out in the field, try to explain it to an engineer and I was told "that can't be right, you're not seeing that." Sometimes photos weren't even convincing. 

I call this the "Platypus syndrome." From what I understand when the Platypus was first discovered, this animal with a beaver's body, webbed feet a duck bill, laid eggs and had a poisonous spur was described to scientists in England who said "that cant be, you didn't see that." Of course a specimen had to be delivered as proof.

In lieu of the groundhog, I think we should make the Platypus the official mascot of this thread.

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## GrauGeist (May 22, 2021)

FLYBOYJ said:


> In lieu of the groundhog, I think we should make the Platypus the official mascot of this thread.


Or the magic unicorn thread...

Either way works

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## Marcel (May 22, 2021)

You guys are amazing, I go to sleep for a few hours and when I come back you have added another 6 pages to this thread. Just keep on it, this thread might reach the distinguished status of the “colour for a model I’m building” thread.

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## BiffF15 (May 22, 2021)

In honor of this and many other threads (all now locked).

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## buffnut453 (May 22, 2021)

To paraphrase:

"'Tis but a scratch"

"A scratch? I removed your armored gearbox"

"No you didn't"

"Look you stupid bastard, you've got no IFF left!"

"It's just a flesh wound!"


And on...and on....and on....and on, ad nauseam!

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## buffnut453 (May 22, 2021)

FLYBOYJ said:


> In lieu of the groundhog, I think we should make the Platypus the official mascot of this thread.



Sounds like the Greater Spotted Platyhog!

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## Thumpalumpacus (May 22, 2021)

wuzak said:


> The remote gearbox surely allows for the installation of a 20mm Vulcan in the nose firing through the hub, instead of the 37mm.



Maybe you could use the gun's revolving action to add a boost to the prop for some extra speed!

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## Crimea_River (May 22, 2021)

The P-39 does have beautiful plumage though.


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## SaparotRob (May 22, 2021)

I agree with Marcel.

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## Snautzer01 (May 22, 2021)

Crimea_River said:


> The P-39 does have beautiful plumage though.


Yes but it keeps pining for the fjords.

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## Peter Gunn (May 22, 2021)

I almost hate to chime in on this thread anymore but smart decisions are not my forte.

RE: 37mm cannon.

Waaaay back in the dark ages of the 1970's when I was still in GA and was the dumb kid working at the airport I knew a fellow that would come out every so often to fly. He had been an actual honest to Yeager P-39 pilot in the SWP. The one tidbit I remember was how much he disliked the 37mm cannon for anything other than landscaping. The trajectory was terrible he said, like a rainbow. It fired too slow and he couldn't hit anything with it in the air, he did however favor it for shooting up Japanese barges and small craft on the water. He related that one time he put a 37mm round into a barge carrying troops, he said it rattled around like a pinball in a bathtub and made a real mess. It was one of the times he threw up in the cockpit. I can only imagine what that did to human flesh and bone... ugh.

I see a lot of balloon juice here about how magnificent the 37 was for firepower, strange that a real pilot who flew it in combat did not think so. I'm sure someone will be happy to refute this with a chart or a graph or some such drivel showing how wrong my old friend was.

Fortunately he survived his time in the P-39 (his words btw) and his next assignment to a front line squadron was with his true love, the Cadillac of the Skies.

Also, regarding another post up thread, the air war was won by the time the P-51D arrived? News to me.

Also regarding the P-39 being a "beast down low", I think Buzz Wagner would disagree with you.

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## GregP (May 22, 2021)

Our new logo:







The angry Platypus - "We are Platypus! Resistance is futile! We saw what you did and we know who you are! An avenging 5,500-pound P-39 without nose armor shall wipe you from the face of the Earth and it will do the job better than any other airplane in the inventory!"

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## SaparotRob (May 22, 2021)

I bow down before The Mighty Platypus.


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## GregP (May 22, 2021)

Well .... OK... but don't let it happen again! ... and another thing, get rid of that pesky nose armor!

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## GregP (May 22, 2021)

Wait ... this is a joke, right?






"Get out of the way, you billigan!"

If you squeeze the airplane to make it shorter, the CG will still be aft of limit, but not nearly as far aft of limit as it was before being squeezed, so it should fly better than before. Or something like that. And, if you painted a swastika on it, it would beat everything else in the sky! Then, BOTH sides would be flying P-39s! The one with the swastika would win, right?

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## fubar57 (May 22, 2021)

That's how you sort out the CoG

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## SaparotRob (May 22, 2021)

The things one learns here.

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## P-39 Expert (May 22, 2021)

Shortround6 said:


> Quite right, a hit _assuming_ there is one will ruin your day. '
> How good is your day if you are hit by 16 20mm shells?
> Difference in the rate of fire of the 37mm and four 20mm Hispano guns.
> The Hispano guns, being higher velocity, are easier to hit with.
> ...


Use the N.


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## P-39 Expert (May 22, 2021)

Glider said:


> *From the web site you quoted*
> 
> *August 1943.*
> Cleaning up.
> ...


So when did this cleaned up Typhoon actually enter combat?


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## P-39 Expert (May 22, 2021)

FLYBOYJ said:


> I do know that, but you continue to try to use issues like this to justify most of your arguments. And again, if you take weight out of the nose by installing a lighter cannon you’re making matters worse! If you want, I’ll do a weight balance calculation with a 20 mm cannon and remove the gear box armor.
> 
> *This tells me that the P-400 probably had ballast in the nose along with that (drumroll) gear box armor!*
> 
> BTW - You "balance" on a see-saw, you "balance" on a tight rope, you get an airplane in "Center of Gravity Range" or *C/G*.


I agree with you, but this just proves Bell could ballast the plane to stay in its CG envelope.

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## GregP (May 22, 2021)

Is this the C.G envelope we are talking about?

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## FLYBOYJ (May 22, 2021)

P-39 Expert said:


> I agree with you, but this just proves Bell could ballast the plane to stay in its CG envelope.


And ballast is sometimes *necessary EXTRA weight* needed to make the aircraft fly better if at all!! * The same as leaving the GB armor installed!!!! Again, why do you think the Soviets did not remove this!!!*

Something posted earlier about the P-63...

_In February 1944, the Soviet government sent a highly experienced test pilot, Andrey G. Kochetkov, and an aviation engineer, Fyodor P. Suprun, to the Bell factories to participate in the development of the first production variant, the P-63A. Initially ignored by Bell engineers, Kochetkov's expert testing of the machine's spin characteristics (which led to airframe buckling) eventually led to a significant Soviet role in the development. After flat spin recovery proved impossible, and upon Kochetkov's making a final recommendation that pilots should bail out upon entering such a spin, he received a commendation from the Irving Parachute Company. *The Kingcobra's maximum aft CG was moved forward to facilitate recovery from spins*.

Most significantly, Soviet input resulted in *moving the main cannon forward, favorably changing the center of gravity*, and increasing its ammo load from 30 to 58 rounds for the A-9 variant._

Gordon, Yefim. _Soviet Air Power in World War 2_. pp 450–451
Dean, Francis H. _America's Hundred Thousand_ pp 410, 602

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## BiffF15 (May 22, 2021)

Interesting points FBJ. The number 1 customer goes to the manufacturer, is initially ignored, but later proves his point to such an extent that changes are made (moving the CG FORWARD) of version 2.0 of the Cobra. With all that Bell knew about the P-39 it’s interesting to see what they initially got wrong on the P-63. It’s almost as if they thought they were smarter than the user. And looking at Bell through that perspective might give one pause.

Cheers,
Biff

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## FLYBOYJ (May 22, 2021)

BiffF15 said:


> Interesting points FBJ. The number 1 customer goes to the manufacturer, is initially ignored, but later proves his point to such an extent that changes are made (moving the CG FORWARD) of version 2.0 of the Cobra. With all that Bell knew about the P-39 it’s interesting to see what they initially got wrong on the P-63. It’s almost as if they thought they were smarter than the user. And looking at Bell through that perspective might give one pause.
> 
> Cheers,
> Biff



Thanks Biff - but OH, *LOOKIE HERE!!!*

_"The weight distribution of the P-39 was supposedly the reason for its tendency to enter a dangerous flat spin, a characteristic Soviet test pilots were able to demonstrate to the skeptical manufacturer who had been unable to reproduce the effect. *After extensive tests, it was determined the spin could only be induced if the aircraft was improperly loaded, with no ammunition in the front compartment*. *The flight manual noted a need to ballast the front ammunition compartment with the appropriate weight of shell casings to achieve a reasonable center of gravity."*_

_Dean, Francis H. America's Hundred Thousand _P 200

*So with that said, do you think anyone in their right mind would want to remove the 70 pounds of armor from the gear box????*

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## pbehn (May 22, 2021)

FLYBOYJ said:


> And ballast is sometimes *necessary EXTRA weight* needed to make the aircraft fly better if at all!! * The same as leaving the GB armor installed!!!! Again, why do you think the Soviets did not remove this!!!*
> 
> Something posted earlier about the P-63...
> 
> ...


So after 5 years the operator is still telling the designer and constructor how to sort it out?

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## FLYBOYJ (May 22, 2021)

pbehn said:


> So after 5 years the operator is still telling the designer and constructor how to sort it out?



And this is one of the reasons why, IMO, Bell Aircraft ceased to be a major player in providing the US government with fighter aircraft in the post war years.

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## GregP (May 22, 2021)

Only a Groundhog Platypus would remove the armor.

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## pbehn (May 22, 2021)

GregP said:


> Only a Groundhog Platypus would remove the armor.


I didnt realise how much Monty Platypus humour was influenced by the P-39, until I saw this thread.


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## P-39 Expert (May 22, 2021)

FLYBOYJ said:


> And this is one of the reasons why, IMO, Bell Aircraft ceased to be a major player in providing the US government with fighter aircraft in the post war years.


That's odd, isn't Bell still to this day supplying aircraft to all four services?


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## P-39 Expert (May 22, 2021)

FLYBOYJ said:


> Thanks Biff - but OH, *LOOKIE HERE!!!*
> 
> _"The weight distribution of the P-39 was supposedly the reason for its tendency to enter a dangerous flat spin, a characteristic Soviet test pilots were able to demonstrate to the skeptical manufacturer who had been unable to reproduce the effect. *After extensive tests, it was determined the spin could only be induced if the aircraft was improperly loaded, with no ammunition in the front compartment*. *The flight manual noted a need to ballast the front ammunition compartment with the appropriate weight of shell casings to achieve a reasonable center of gravity."
> Reply: *_*This is saying that with the spent shell casings still in the front fuselage would achieve a reasonable center of gravity.*
> ...



To save 70lbs of weight. The plane could easily be balanced by moving or removing the IFF radio. And the plane entered the spin with no ammo in the nose. But the weight of the spent shell casings still in the nose would achieve a reasonable center of gravity. Not likely to go into combat with no ammunition in the front compartment.


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## FLYBOYJ (May 22, 2021)

P-39 Expert said:


> To save 70lbs of weight. The plane could easily be balanced by moving or removing the IFF radio.


And I showed you* over and over* that if you do this you're still AFT in the CG ENVELOPE!!!

and...you keep saying the Soviets REMOVED their IFF - *THEN WHY DIDN'T THEY REMOVE THE GEAR BOX ARMOR???? PLEASE ANSWER THIS QUESTION?!?!?*

And again - you "balance" see-saws and spinning plates.



P-39 Expert said:


> And the plane entered the spin with no ammo in the nose. But the weight of the spent shell casings still in the nose would achieve a reasonable center of gravity.


Not with 70 pounds of armor removed!!!!

Oh - the cannon shell casing mod - WHY WAS THAT DONE? APPARENTLY THE SOVIETS SHOWED THE NEED FOR IT!


P-39 Expert said:


> Not likely to go into combat with no ammunition in the front compartment.


*No, but you're hopefully gonna fly home that way LOL!!!!!*


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## FLYBOYJ (May 22, 2021)

P-39 Expert said:


> That's odd, isn't Bell still to this day supplying aircraft to all four services?


Not fighter aircraft - "Bell Helicopters" Larry Bell and his exaggerations, if not flat out lies put an end to that!!!!


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## GregP (May 22, 2021)

Bell is still supplying aircraft to the U.S. Government, just not fighter aircraft. Their last fighter made in any numbers was the P-63, though they DID make one XP-77 and two XP-83s.

Oops FBJ, saw your post when I posted this. Nevermind ...

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## buffnut453 (May 22, 2021)

Other than the CofG problem, would a weight reduction of just 1/100th of the gross weight result in any substantive performance improvements? Given that the performance within a production batch of "identical" airframes can change by +/-5% (or perhaps even more), removing 70lbs is kindda in the noise (IMHO).

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## FLYBOYJ (May 22, 2021)

buffnut453 said:


> Other than the CofG problem, would a weight reduction of just 1/100th of the gross weight result in any substantive performance improvements? Given that the performance within a production batch of "identical" airframes can change by +/-5% (or perhaps even more), removing 70lbs is kindda in the noise (IMHO).



And keeping it in place moves the C/G forward over 2 inches in some configurations!!!


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## pbehn (May 22, 2021)

P-39 Expert said:


> To save 70lbs of weight. .


You cannot call 70lbs "weight" without some risk of terminological inexactitude. It may be enough to change a CoG calculation but is probably less than the difference between the heaviest and lightest pilot. Work it out in terms of gallons of fuel coolant and oil.

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## Glider (May 22, 2021)

P-39 Expert said:


> So when did this cleaned up Typhoon actually enter combat?


It was a standard production fit from Nov 43 and conversion kits were produced so aircraft could be modified in the field. There was as you would expect a transition period, and just by looking at photographs, its rare to find a photo of the old 'car door' version after March/April 44. I have a couple of photo's of squadrons in flight dated March 44 in my book on the 2TAF and both versions are in both photo's
I wouldn't be surprised if there wasn't a push to get it as a standard equipment for the invasion, but cannot guarantee that.


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## P-39 Expert (May 22, 2021)

Shortround6 said:


> "* I just looked it up and the exact weight is 5849lbs gross per the contract signed in Feb 1940. This weight was the basis for the 400mph estimates, aka P-400. Final gross weight after the British finished with it in 1941 was 7850lbs"*
> 
> 
> Hmm, strangely enough, the P-39C went 5,070lbs empty, 7075lbs gross weight (combat) and 7300lbs max gross. They were ordered August 10th 1939. So, in Feb of 1940, 6 months later Bell is telling the British the plane will only weigh 5879lbs gross for combat?
> ...



Please expand above.


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## pbehn (May 22, 2021)

P-39 Expert said:


> Please expand above.


Why didnt Bell supply the Russians nice light planes without the impositions of Perfide Albion?


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## P-39 Expert (May 22, 2021)

GrauGeist said:


> The range of the P-39 was half that of Navy fighters.
> The F4U's range was 1,000 miles.
> The F6F's range was 945 miles.
> The F4F's range was 845 miles.
> ...


Please produce your source on those ranges, but they computed range differently than the AAF. Computed the army way with the appropriate takeoff and climb allowance, cruise out at high altitude, 20 minutes of combat and cruise back at high altitude with the appropriate reserve for landing the ranges were very close.


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## FLYBOYJ (May 22, 2021)

pbehn said:


> Why didnt Bell supply the Russians nice light planes without the impositions of Perfide Albion?



*WHY DIDN'T THE RUSSIANS REMOVE THE GEAR BOX ARMOR! *


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## P-39 Expert (May 22, 2021)

FLYBOYJ said:


> *WHY DIDN'T THE RUSSIANS REMOVE THE GEAR BOX ARMOR! *


Obviously they chose not to, for whatever reason. I never said that *anyone ever *removed the gear box armor. It's just an idea. But if they did, appropriate measures could be taken to keep the plane within the CG limits. That's all I have ever said. And you really can't argue that point.


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## FLYBOYJ (May 22, 2021)

P-39 Expert said:


> Please produce your source on those ranges, but they computed range differently than the AAF. Computed the army way with the appropriate takeoff and climb allowance, cruise out at high altitude, 20 minutes of combat and cruise back at high altitude with the appropriate reserve for landing the ranges were very close.


Tell you what - let's see *YOU* calculate the maximum P-39 range (any model you want) "with the appropriate takeoff and climb allowance, cruise out at high altitude, 20 minutes of combat and cruise back at high altitude with the appropriate reserve for landing."


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## FLYBOYJ (May 22, 2021)

P-39 Expert said:


> Obviously they chose not to, for whatever reason. I never said that *anyone ever *removed the gear box armor. It's just an idea. But if they did, appropriate measures could be taken to keep the plane within the CG limits. That's all I have ever said. And you really can't argue that point.



And you're arguing a hypothetical idea that was clearly shown *WHY *it shouldn't be done, this based on historical records to show both the P-39 AND P-63 had aft C/G issues clearly identified by the Soviets!!!!


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## P-39 Expert (May 22, 2021)

Peter Gunn said:


> I almost hate to chime in on this thread anymore but smart decisions are not my forte.
> 
> RE: 37mm cannon.
> 
> ...


The cannon was always an enigma. The P-39 was the only AAF plane that used it. From what I have read the combat pilots were split about 50/50 vs. the alternate 20mm cannon in the P-400 and P-39D-1. The 37mm advocates liked its destructive power, the 20mm men liked the longer range and higher rate of fire. Personally I think I would have preferred the 20mm for the same reasons plus the lower weight.


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## Thumpalumpacus (May 22, 2021)

BiffF15 said:


> Interesting points FBJ. The number 1 customer goes to the manufacturer, is initially ignored, but later proves his point to such an extent that changes are made (moving the CG FORWARD) of version 2.0 of the Cobra. With all that Bell knew about the P-39 it’s interesting to see what they initially got wrong on the P-63. It’s almost as if they thought they were smarter than the user. And looking at Bell through that perspective might give one pause.
> 
> Cheers,
> Biff



I think one reason why Grumman, Boeing, and other companies stayed in business while Brewster and Curtiss did not is exactly this: listening to the end users, and putting those mods into place efficiently.

There are, of course, other factors as well -- Brewster's shoddy workmanship, Curtiss' designs being regularly a year or two behind cutting-edge -- but you get my point.

ETA: I edited this post to remove Bell from the list of has-beens because they did of course do good work on heloes for decades after WWII.

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## GrauGeist (May 22, 2021)

P-39 Expert said:


> Please produce your source on those ranges, but they computed range differently than the AAF. Computed the army way with the appropriate takeoff and climb allowance, cruise out at high altitude, 20 minutes of combat and cruise back at high altitude with the appropriate reserve for landing the ranges were very close.


You're the expert - look it up yourself.

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## FLYBOYJ (May 22, 2021)

P-39 Expert said:


> Personally I think I would have preferred the 20mm for the same reasons plus the lower weight.


Along with gear box armor and ballast in the nose!


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## Thumpalumpacus (May 22, 2021)

P-39 Expert said:


> And the plane entered the spin with no ammo in the nose. But the weight of the spent shell casings still in the nose would achieve a reasonable center of gravity. Not likely to go into combat with no ammunition in the front compartment.



But more likely to experience that circumstance at the end of a mission, slowing and turning on approach. A crashed plane is a crashed plane, and a low-altitude stall is a bitch.

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## FLYBOYJ (May 22, 2021)

P-39 Expert said:


> I never said that *anyone ever *removed the gear box armor. It's just an idea. But if they did, appropriate measures could be taken to keep the plane within the CG limits.



Yep - by putting 90 pounds of ballast in the nose!

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## Thumpalumpacus (May 22, 2021)

FLYBOYJ said:


> Yep - by putting 90 pounds of ballast in the nose!



That sounds like an angry sergeant in maintenance detailing his sad-sack to digging and filling a hole, lol.

(Never saw that, just heard the old-timers talk about it.)

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## pbehn (May 22, 2021)

FLYBOYJ said:


> Yep - by putting 90 pounds of ballast in the nose!


I was joking when I suggested that  What was it about Bell that made them so "special". North American managed to make one of the foremost fighters, one of the foremost trainers and one of the most versatile twin engined planes in the whole war, did they ever have an issue that plagued these planes from start to finish without a cure coming from them and not someone else? As far as I can see they just said "yes sir, but you need to consider this or limit that, and put it in the pilots notes" they didnt pretend that a P-51 with maximum fuel was anything other than a potential accident on take off, but between client and manufacturer they made it work.

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## FLYBOYJ (May 22, 2021)

Thumpalumpacus said:


> ETA: I edited this post to remove Bell from the list of has-beens because they did of course do good work on heloes for decades after WWII.



Bell was successful with helicopters because of the very talented Arthur Young. Personally after all the SNAFUs encountered during WW2 and with other manufacturers surpassing Bell's ability to design and produce modern fighter aircraft, I think it was a smart business move to concentrate on helicopters as the core business. Larry Bell died in 1956 IIRC but the helicopter division flourished until it was sold to Textron in 1960. By then it was an entirely different company.

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## pbehn (May 22, 2021)

I read years ago in a link I can no longer find that RAF 601 squadron had a Russian aviation expert attached to them when they were using the P-39. So when the P-39 arrived in Russia they had a good idea of what to do to make it a success. (Maybe 

 Dimlee
can help with this). Did Bell have their own test pilots or any real feedback from pilots in the field? I just cant understand why this CoG issue went on throughout the war, with Bell designing a replacement for the P-39 and designing in the same ffing problem.

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## Thumpalumpacus (May 22, 2021)

FLYBOYJ said:


> Bell was successful with helicopters because of the very talented Arthur Young. Personally after all the SNAFUs encountered during WW2 and with other manufacturers surpassing Bell's ability to design and produce modern fighter aircraft, I think it was a smart business move to concentrate on helicopters as the core business. Larry Bell died in 1956 IIRC but the helicopter division flourished until it was sold to Textron in 1960. By then it was an entirely different company.




All very true, their fixed-wing business was, I think, killed in large part by the -39/-63 experiences USAAF had during the war. I was just trying to be very accurate with that edit, and acknowledging their work (which was obviously good) in rotary-wing stuff.

Just like their airplanes, Bell was itself a pretty quirky company, so far as I've read. "Quirky" and _military_ don't often play well together.

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## FLYBOYJ (May 22, 2021)

pbehn said:


> I read years ago in a link I can no longer find that RAF 601 squadron had a Russian aviation expert attached to them when they were using the P-39. So when the P-39 arrived in Russia they had a good idea of what to do to make it a success. (Maybe
> 
> Dimlee
> can help with this). Did Bell have their own test pilots or any real feedback from pilots in the field? I just cant understand why this CoG issue went on throughout the war, with Bell designing a replacement for the P-39 and designing in the same ffing problem.



I think the Soviets did everything they could to make the P-39 a formidable weapon. I also think the environment the Soviets operated the P-39 in was the perfect niche for this aircraft. Agree with our "Expert" friend, "remove the wing guns and the IFF (with the Soviets not having a requirement for IFF, a little crazy if you ask me!) Earlier I showed some calculations that with the IFF removed and the radios moved forward, you're going to get the CG within the middle range with ammo depleted and 1/4 full tanks, even further forward when full of fuel and fully armed. The Soviets knew the P-39 (and P-63) was tail heavy as documented, so I think they might have done other things to get C/G to move more forward (ballast?)

As far as the AAF - in the Pacific the P-39 (along with the P-40) was doomed to be pushed aside by the P-38, a weapon the 5th AF General Kenny made his primary acquisition. In The Med and Europe, we saw how quickly the P-39 was placed in secondary roles once other aircraft came on scene, so I think the AAF knew of these deficiencies and just operated around them.

We do know a lot of P-39s were used in training, many were also lost (like other aircraft of the day) but that's naturally going to happen in a training environment.

I find it funny that after all the controversy with the P-39, folks at Bell STILL continued to ignore lessons learned when they were developing the P-63.

As well documented, some pilots loved the aircraft many hated it. It's reputation wasn't set by a few disgruntled pilots, every WW2 fighter pilot I ever met who flew the aircraft did not have favorable things to say about it, at least two that I can recall "hated it." Instead of trying to theorize what "should have" been done, or what "could have" I think more emphasis should be placed on how it was operated, where it succeeded and where it failed. Historical facts rather than armchair engineering.

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## Thumpalumpacus (May 22, 2021)

Kenney was very astute, one of the best USAAF generals in my humble opinion. He wasn't beholden to gear -- he rejected the A-26 in favor of more B-25s -- so when he said some gear was crap, I'm inclined to pay the hell attention.

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## pbehn (May 22, 2021)

FLYBOYJ said:


> I think the Soviets did everything they could to make the P-39 a formidable weapon. I also think the environment the Soviets operated the P-39 in was the perfect niche for this aircraft. Agree with our "Expert" friend, "remove the wing guns and the IFF (with the Soviets not having a requirement for IFF, a little crazy if you ask me!) Earlier I showed some calculations that with the IFF removed and the radios moved forward, you're going to get the CG within the middle range with ammo depleted and 1/4 full tanks, even further forward when full of fuel and fully armed. The Soviets knew the P-39 (and P-63) was tail heavy as documented, so I think they might have done other things to get C/G to move more forward (ballast?)
> 
> As far as the AAF - in the Pacific the P-39 (along with the P-40) was doomed to be pushed aside by the P-38, a weapon the 5th AF General Kenny made his primary acquisition. In The Med and Europe, we saw how quickly the P-39 was placed in secondary roles once other aircraft came on scene, so I think the AAF knew of these deficiencies and just operated around them.
> 
> ...


One thing I picked up from reading various "bits" was that on the eastern front rate of roll was prized over rate of turn. If conflict starts at a lower altitude and they all descend to the ground then rate of roll is more important and ditching wing guns is one of the few things you can do to improve it.

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## wuzak (May 22, 2021)

P-39 Expert said:


> The cannon was always an enigma. The P-39 was the only AAF plane that used it. From what I have read the combat pilots were split about 50/50 vs. the alternate 20mm cannon in the P-400 and P-39D-1. The 37mm advocates liked its destructive power, the 20mm men liked the longer range and higher rate of fire. Personally I think I would have preferred the 20mm for the same reasons plus the lower weight.



The P-38 was supposed to get the 37mm, but they switched to the 20mm and never considered going back.

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## Shortround6 (May 22, 2021)

*"The P-39C may have been ordered in August 1939 but the first production delivery was in January 1941 and it suffered substantial weight gain during production like the P-400. The weight specified on the contract was substantially lower, more like the original P-400 weight."*

And why the weight gain?

You are the one claiming the British started specifying all manor of extraneous stuff to get the weight up and the Performance down AFTER The BoB in order to get out of a cash contract. 

YP-39, was first flown on September 13, 1940, same day the USAAC ordered the P-39Ds. One source says "Empty and normal loaded weights rose to 5042 pounds and 7000 pounds, respectively. "

Bell simply could not deliver a working (or read viable) combat aircraft at the weights specified in the contract. Yet you want to blame the British. 

" *Okay, in detail (AHT) the P-39D weighed 5523lbs empty and grossed 7690lbs. The P-400 weighed 5550lbs empty and grossed 7700lbs even. You can look for the 10lb difference if you like."*

If that is what you consider "detail" it is no wonder these threads have dragged out so long*. *

I will try to be plainer.

Please list all of the items that the British specified that ran the weight up over and above the weights for the YP-39 or P-39C. 
Items that the USAAC did not specify for either the P-39C or the P-39D so that we can see exactly how the British were trying to get out of the contract. 

Don't bother just copying the gross weights. I am looking the the specific item or items of equipment that ran the weight up that weren't needed for a successful combat fighter of the time. 

You made the claim the British ran the weight up unnecessarily. Show us how.


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## GrauGeist (May 22, 2021)

wuzak said:


> The P-38 was supposed to get the 37mm, but they switched to the 20mm and never considered going back.


It's almost funny how various air forces had their obsessions: The RLM wanted everything to be a dive-bomber, the USAAC/USAAF wanted everything to have a 37mm cannon and so on...


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## wuzak (May 22, 2021)

Could this have been the solution to the CoG probelms?

Bell P-63 Kingcobra



johnbr said:


> Bell L-39
> View attachment 543158
> View attachment 543159
> View attachment 551806

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## GrauGeist (May 22, 2021)

Messerschmitt altered the Me262's wings to address CoG issues, so that might be one avenue to explore.


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## pbehn (May 22, 2021)

Shortround6 said:


> You made the claim the British ran the weight up unnecessarily. Show us how.


The British just wanted to screw up anything that came from the USA, its a historical fact, as can be seen from the P-40 and P-51. Actually it is utter bollocks. The British were doing R&D on the P-39 in a way they were never required to on the P-40 and P-51 which pretty much did what was said on the tin. This line of discussion from the expert holds no water at all.

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## Thumpalumpacus (May 22, 2021)

pbehn said:


> The British just wanted to screw up anything that came from the USA, its a historical fact, as can be seen from the P-40 and P-51. Actually it is utter bollocks. The British were doing R&D on the P-39 in a way they were never required to on the P-40 and P-51 which pretty much did what was said on the tin. This line of discussion from the expert holds no water at all.



The British had as much experience in air combat as anyone in the world, in 1941. Their not liking the -39 speaks volumes when we keep this in mind. After the BoB they knew what they needed, and the -39 was not it. They knew bullshit when they saw it.

That the VVS got more out of it in their combat milieu was great. Goes to show how operational needs and circumstances can affect the utility of gear. It also shows how narrow was the utility of the -39, to me.

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## GrauGeist (May 22, 2021)

The Soviets were in dire need of anything they could get their hands on in the first years of the war.
I am certain that if they were given Brewster Buffalos or Blackburn Rocs, they would have made those work, too.

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## ThomasP (May 23, 2021)

P-39 Maximum Range - internal fuel with fuel for WUTO & climb to 10,000 ft not available for range:
P-39D____600 miles at 232 mph TAS at 10,000 ft___2600 rpm at 26"Hg__120 USgal
P-39N____360 miles at 250 mph TAS at 10,000 ft___2650 rpm at 26"Hg___87 USgal
P-39Q____530 miles at 240 mph TAS at 10,000 ft___2650 rpm at 26"Hg__120 USgal

As to the CG issue:
I may be misremembering, but I believe the P-39N model incorporated changes to alleviate the out-of-CG problem due to the expenditure of the nose gun ammo. What the exact changes were I do not know.

As to the change of/removal of armour:







As to the weight of the radio equipment in the aft compartment, and possible movement of it to correct CG:

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## FLYBOYJ (May 23, 2021)

ThomasP said:


> As to the CG issue:
> I may be misremembering, but I believe the P-39N model incorporated changes to alleviate the out-of-CG problem due to the expenditure of the nose gun ammo. What the exact changes were I do not know.



I believe a catch box was installed to maintain the shell casings from the cannon


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## wuzak (May 23, 2021)

So the IFF components ("pipsqueak") amounted to only a few pounds?


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## FLYBOYJ (May 23, 2021)

ThomasP said:


> As to the weight of the radio equipment in the aft compartment, and possible movement of it to correct CG:
> 
> View attachment 624357



This is great but there is also an installation that goes behind the pilot;












Looks like this is the SCR-535A IFF


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## FLYBOYJ (May 23, 2021)

And it may look something like this;


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## P-39 Expert (May 23, 2021)

FLYBOYJ said:


> I believe a catch box was installed to maintain the shell casings from the cannon


The spent shells from both the cannon and two 50calMGs were collected in the nose on all production models, no shell casings were ejected overboard from the nose. Measures were taken to alleviate any CG issues on the P-39N but that was not one of them.


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## P-39 Expert (May 23, 2021)

Shortround6 said:


> *"The P-39C may have been ordered in August 1939 but the first production delivery was in January 1941 and it suffered substantial weight gain during production like the P-400. The weight specified on the contract was substantially lower, more like the original P-400 weight."*
> 
> And why the weight gain?
> 
> ...


Let me be as plain as I can be. The British specified the 30cal wing guns (about 400lbs with 4000 rounds of ammunition) and excessive armor plate (almost 300lbs when 125 would have been plenty). That's almost 600lbs of unnecessary/redundant weight among other items. Remove that and the P-39 had very competitive performance.

If you want specifics, just open up your copy of AHT and turn to the P-39 chapter. Item by item weights are all right there.


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## P-39 Expert (May 23, 2021)

Glider said:


> It was a standard production fit from Nov 43 and conversion kits were produced so aircraft could be modified in the field. There was as you would expect a transition period, and just by looking at photographs, its rare to find a photo of the old 'car door' version after March/April 44. I have a couple of photo's of squadrons in flight dated March 44 in my book on the 2TAF and both versions are in both photo's
> I wouldn't be surprised if there wasn't a push to get it as a standard equipment for the invasion, but cannot guarantee that.


So the better performance had to wait until 1944? I'm talking about 1942 and 1943.


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## BiffF15 (May 23, 2021)

And here we go again.

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## rochie (May 23, 2021)

The P-39 should be made a political topic on this forum. 
Then we might be spared this endless back and fourth!

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## wuzak (May 23, 2021)

P-39 Expert said:


> Let me be as plain as I can be. The British specified the 30cal wing guns (about 400lbs with 4000 rounds of ammunition) and excessive armor plate (almost 300lbs when 125 would have been plenty). That's almost 600lbs of unnecessary/redundant weight among other items. Remove that and the P-39 had very competitive performance.



What extra armor was added by the British compared to the contemporary P-39?



> The Airacobra I was powered by an Allison V-1710-E4 twelve-cylinder V in-line engine rated at 1150 hp for takeoff. *Weights were 5462* pounds empty and *7845 pounds normal gross*. Maximum speeds were 326 mph at 6000 feet, 343 mph at 10,000 feet, 355 mph at 13, 000 feet, 341 mph at 20,000 feet. Initial climb rate was 2040 feet per minute. With an internal fuel capacity of 100 Imp gal the Airacobra had an endurance of 1 hour 20 minutes at maximum continuous cruising speed at 6000 feet, 1 hour 5 minutes at 12,000 feet, and 1 hour 35 minutes at 20,000 feet. The true airspeeds at these altitudes were 287 mph, 327 mph, and 308 mph, respectively. Under most economical cruise conditions, the endurance increased to 3 hours 20 minutes, the relevant speeds being 183 mph at 6000 feet, 217 mph at 12,000 feet, and 215 mph at 20,000 feet. Under maximum continuous climb conditions, it took 15 minutes to reach 20,000 feet. The operational ceiling was considered to be about 24,000 feet, although there was a marked decrease in performance above 20,000 feet. At the Airacobra's rated altitude of 13,000 feet, it was 18 mph faster than the Spitfire VB. However, the speed fell off rapidly above that height, and the two planes were almost exactly matched at 15,000 feet. At 20,000 feet, the Spitfire VB was 35 mph faster and at 24,000 feet it was 55 mph faster. The ground run of the Airacobra during takeoff was 2250 feet, as compared with 1470 feet for the Hurricane II and 1590 feet for the Spitfire V.



Airacobra I for RAF, P-400




> Engine: One 1150 hp Allison V-1710-35 twelve-cylinder liquid cooled engine. Performance: Maximum speed 309 mph at sea level, 335 mph at 5000 feet, 355 mph at 10,000 feet, 368 mph at 12,000 feet, and 360 mph at 15,000 feet. An altitude of 5000 feet could be reached in 1.9 minutes. It took 5.7 minutes to reach an altitude of 15,000 feet and 9.1 minutes to reach 20,000 feet. Service ceiling was 32,100 feet. Maximum range (clean) was 600 miles at 10,000 feet at 231 mph. Range with one 145.7 Imp gal drop tank was 1100 miles at 196 mph. *Weights: 5462 pounds empty*, *7500 pounds gross*, and 8200 pounds maximum takeoff. Dimensions: Wingspan 34 feet 0 inches, length 30 feet 2 inches, height 11 feet 10 inches, and wing area 213 square feet. Armament: One 37-mm cannon in the nose with 30 rounds. Four wing-mounted 0.30-inch machine guns with 1000 rpg, two fuselage-mounted 0.50-inch machine guns with 200 rounds per gun. One 250 lb, 325-lb, or 500-lb bomb could be carried underneath the fuselage.



Bell P-39D Airacobra

Compared to the D the Airacobra I had the same empty weight, it had the 20mm vs the 37mm, both had the cowl 0.5" HMGs, the US 0.30" LMGs were replaced by British 0.303" LMGs.

The gross weight was more for the Airacobra I, but that is to do with fuel, ammo, oil, etc. Not armour plating.


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## wuzak (May 23, 2021)

P-39 Expert said:


> So the better performance had to wait until 1944? I'm talking about 1942 and 1943.



I believe the improvements were introduced in 1943. 

Glider was pointing out that the older Typhoons had (mostly?) gone by early 1944.


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## P-39 Expert (May 23, 2021)

FLYBOYJ said:


> Tell you what - let's see *YOU* calculate the maximum P-39 range (any model you want) "with the appropriate takeoff and climb allowance, cruise out at high altitude, 20 minutes of combat and cruise back at high altitude with the appropriate reserve for landing."


Gladly. P-39N with 120gal internal less 16gal res. for T/O&Climb, 24gal for combat at 25000', and 10gal reserve for landing nets 70gal x 344mph cruising speed = 378mi. range.
F4U calculated the AAF way 237gal internal less 45gal for T/O&Climb, 93gal for 20min combat at 25000', and 20gal reserve for landing nets 79gal x 344mph cruising = 292mi range. F4U cruising speed was estimated, not in the pilot's manual.

That's for an AAF interception or escort mission at 25000ft. Both straight from the pilot's manuals. Range includes distance covered in climb but not descent. That R-2800 was a gas hog.


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## buffnut453 (May 23, 2021)

P-39 Expert said:


> Let me be as plain as I can be. The British specified the 30cal wing guns (about 400lbs with 4000 rounds of ammunition) and excessive armor plate (almost 300lbs when 125 would have been plenty). That's almost 600lbs of unnecessary/redundant weight among other items. Remove that and the P-39 had very competitive performance.
> 
> If you want specifics, just open up your copy of AHT and turn to the P-39 chapter. Item by item weights are all right there.



So you're saying that the customer was asking for 30cal machine guns which were unnecessary/redundant? Really? I'd have thought the RAF, coming hot out of the Battle of Britain, would have a pretty solid idea of what they wanted in a fighter.

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## pbehn (May 23, 2021)

P-39 Expert said:


> Let me be as plain as I can be. The British specified the 30cal wing guns (about 400lbs with 4000 rounds of ammunition) and excessive armor plate (almost 300lbs when 125 would have been plenty). That's almost 600lbs of unnecessary/redundant weight among other items. Remove that and the P-39 had very competitive performance.
> 
> If you want specifics, just open up your copy of AHT and turn to the P-39 chapter. Item by item weights are all right there.


Let me be as clear as I can be, that was less than half of what was fitted to a Typhoon. Operating close to the ground across the channel exposes you to a lot of ground fire.
from wiki on the Typhoon "Because of the vulnerability of the Typhoon's liquid-cooled engine cooling system to ground fire, some 780 pounds (350 kg) of armour was added, lining the sides and bottom of the cockpit and engine compartments, as well as the radiator bath.[67]"


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## P-39 Expert (May 23, 2021)

buffnut453 said:


> So you're saying that the customer was asking for 30cal machine guns which were unnecessary/redundant? Really? I'd have thought the RAF, coming hot out of the Battle of Britain, would have a pretty solid idea of what they wanted in a fighter.


RAF did have a pretty solid idea for armament: the 20mm cannon, which they went to right after the BoB.

Biggest drawback with the 30calMG was effective range was only 200yds (AHT).


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## P-39 Expert (May 23, 2021)

pbehn said:


> Let me be as clear as I can be, that was less than half of what was fitted to a Typhoon. Operating close to the ground across the channel exposes you to a lot of ground fire.
> from wiki on the Typhoon "Because of the vulnerability of the Typhoon's liquid-cooled engine cooling system to ground fire, some 780 pounds (350 kg) of armour was added, lining the sides and bottom of the cockpit and engine compartments, as well as the radiator bath.[67]"


Exactly right, a liquid cooled ground attack fighter will need a LOT of armor protection. How much did a Spitfire V have?


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## pbehn (May 23, 2021)

P-39 Expert said:


> Exactly right, a liquid cooled ground attack fighter will need a LOT of armor protection. How much did a Spitfire V have?


The Spitfire was the high altitude interceptor for the RAF until the end of the war. Thats why it only had 2 cannon.


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## BiffF15 (May 23, 2021)

The wheels on the bus go round and round, round and round…

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## pbehn (May 23, 2021)

buffnut453 said:


> So you're saying that the customer was asking for 30cal machine guns which were unnecessary/redundant? Really? I'd have thought the RAF, coming hot out of the Battle of Britain, would have a pretty solid idea of what they wanted in a fighter.


They did, 4 x 20mm cannon. The P-39 was the most lightly armed of any fighter in RAF service except for Gladiators somewhere in Africa.


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## FLYBOYJ (May 23, 2021)

P-39 Expert said:


> The spent shells from both the cannon and two 50calMGs were collected in the nose on* all production models*, no shell casings were ejected overboard from the nose. Measures were taken to alleviate any CG issues on the P-39N but that was not one of them.


So this shows the criticality of the CG of the aircraft on all production models!


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## SaparotRob (May 23, 2021)

1003 posts left to catch up to roadking01’s thread.


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## buffnut453 (May 23, 2021)

P-39 Expert said:


> RAF did have a pretty solid idea for armament: the 20mm cannon, which they went to right after the BoB.
> 
> Biggest drawback with the 30calMG was effective range was only 200yds (AHT).



And yet the cannon-armed Spitfires in the period 1940-1943 continued with 4x.303 machine guns in addition to the 2x20mm cannon. Perhaps the RAF wanted additional 30cals for the P-400 because they knew that one cannon and two machine guns wouldn't be sufficient for combat operations?


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## wuzak (May 23, 2021)

P-39 Expert said:


> RAF did have a pretty solid idea for armament: the 20mm cannon, which they went to right after the BoB.
> 
> Biggest drawback with the 30calMG was effective range was only 200yds (AHT).



What about the British 0.303"? wasn't that used for the Airacobra I?

There was only 60 rounds for the 20mm in the Airacobra I, compared to 30 rounds of the 37mm.


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## Glider (May 23, 2021)

P-39 Expert said:


> So the better performance had to wait until 1944? I'm talking about 1942 and 1943.



However Also on the web site you mention

*August 1942.*
Cleaning up Typhoon 1.
Level speeds of production aircraft.
Level speeds done at Gloster Aircraft on a Typhoon 1B (R.8705) with short exhaust pipes, gave the following maximum level speeds.

F.S. (M.P.A.) 403.5 m.p.h. at 20,650 ft. M.S. (M.P.A.) 392.5 m.p.h. at 8,750 ft.

These still compare well to the P39N
389mph at 16,100 ft and 398mph at 9,700ft I would suggest both are still pretty equal

I haven't mentioned before the caveat to the P39 figures that you don't mention *Airplane does not meet Air Corps cooling requirements at any of these powers* which begs a few questions over how safe the aircraft was when delivering these figures.

Previous comments re the advantages to the Typhoon of its considerably greater firepower, payload and armoured protection still apply.

The other question which hasn't yet been asked. If the P39N was so good, why did the USA produce the P39Q which was so much slower maxing out at about 385mph?

*A final point* is the handling for the P39Q which presumably applies to the N which you never seem to mention

Conclusions
1. The P-39 should not be spun intentionally under any circumstances.
2. The P-39 should not be snap rolled as the roll usually ends in a spin.
3. The best spin recovery is to simultaneously apply opposite rudder and neutralize the stick.
4. Power should be cut immediately if a power on spin is entered.
5. Care must be excercised during the recovery to prevent an accelerated stall and re-enty into the spin.
6. The wing tip spin chute does not aid recovery of the P-39Q from a flat spin.

A fighter that operates best at low to medium altitude, that cannot snap roll when attacked as there is a significant chance of a spin (at low altitude), isn't a healthy place to be.

Edit Range
I don't have much information about the range of the P39 but if I remember correctly the P39N which you always quote for performance figures only had about 90 gallons of fuel which is on the low side. The P39Q had an increased capacity of 110 gallons which may impact its performance. 
I do know that Typhoons were often used to escort Mosquito's on bombing missions as they were one of the few aircraft with the cruise performance to keep up with the Mosquito and had a range of approx 1000 miles using drop tanks

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## GregP (May 23, 2021)

Radial engine fighters have a very low cruise speed in general. The F4U-4 cruised at 215 mph, and that is a later, faster version of the original F4U. The main reason was fuel burn. I can believe your calculation if you cruise the F4U at 300+ mph! Try a more realistic 200 mph for the F4U and you will get much more real-world results.

Just FYI, an F8F Bearcat that could make 455 mph top speed cruised at 185 mph most of the time for more economical operation. Now, if the F8F was coming up on an areas where combat was likely, then they would speed up so that the energy state was better if combat happened.

Cheers.

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## FLYBOYJ (May 23, 2021)

P-39 Expert said:


> Gladly. P-39N with 120gal internal less 16gal res. for T/O&Climb, 24gal for combat at 25000', and 10gal reserve for landing nets 70gal x 344mph cruising speed = 378mi. range.
> F4U calculated the AAF way 237gal internal less 45gal for T/O&Climb, 93gal for 20min combat at 25000', and 20gal reserve for landing nets *79gal x 344mph cruising = 292mi range.* F4U cruising speed was estimated, not in the pilot's manual.
> 
> That's for an AAF interception or escort mission at 25000ft. Both straight from the pilot's manuals. Range includes distance covered in climb but not descent. That R-2800 was a gas hog.



Several things - The P-39N manual I have shows best fuel consumption climb to 25K at 31.2 GPH at 30 minutes






Then there is no data for a 25K cruising altitude if that was your intention?? *And nowhere do show GPH.*






And you didn't include the 20 gallons for warm up, you use 16 gallons reserve for the P-39 and 20 for the F4U, so I'm not going any further with the P-39

F4U

Way high cruising speed and fuel consumption. Greg beat me to the punch. Try around 200 MPH indicated at around 42 GHP at 5000' for the F4U's best cruise fuel consumption.

Sticking with your initial numbers (which are very wrong)

79 gal @ 42 GPH = 1.88 hrs in the air at 200 mph = 376 miles.


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## pbehn (May 23, 2021)

Glider said:


> I haven't mentioned before the caveat to the P39 figures that you don't mention *Airplane does not meet Air Corps cooling requirements at any of these powers* which begs a few questions over how safe the aircraft was when delivering these figures.
> s


As far as I remember this was the issue that caused 601 squadron so many problems, the engines overheated. Many of the losses were put down as pilot error, and overheating the engine was seen as evidence of a pilot error.


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## ThomasP (May 23, 2021)

Hey P-39 Expert,

1. You forgot to subtract fuel for 20 min Combat at 15,000 ft from the fuel available for range of the P-39. If we use 5 min WEP and 15 min Military, you have to subtract ~48 USgal from the fuel available for range.

2. You used a ridiculously high 344 mph TAS cruise speed for the F4U. The F4U-1 V for best range was 178 mph IAS/182 mph TAS at 1,500 ft.
(I can not say for sure how much more fuel would be used at 344 mph TAS as you did not specify the cruise altitude, but if it was 15,000 ft then the fuel used would be around 3x what it would be at 182 mph IAS/235 mph TAS at 15,000 ft.)






If flown at 182 mph IAS/ 235 mph TAS at 15,000 ft the range would decrease ~15% from the 1015 miles shown above, so a little under 860 miles on internal fuel with no combat or reserves.

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## buffnut453 (May 23, 2021)

There are lies. There are damned lies. And there are P-39Expert's range calculations.

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## ThomasP (May 23, 2021)

PS The ranges I listed in my post#1,438 upthread are from a US(?) document comparing all major models of the P-39. A copy can be found on the wwIIaircraftperformance website here:"http://www.wwiiaircraftperformance.org/P-39/P-39_Aircraft_Performance_Characteristics.jpg"

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## FLYBOYJ (May 23, 2021)

buffnut453 said:


> There are lies. There are damned lies. And there are P-39Expert's range calculations.



"Anyone who calls themselves "an expert" is a specialist who knows everything about something, and nothing about anything else."


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## pbehn (May 23, 2021)

FLYBOYJ said:


> "Anyone who calls themselves "an expert" is a specialist who knows everything about something, and nothing about anything else."


The title "expert" is normally conferred on people by others. I have only met two people who were actually legally defined "experts" they had both been called as expert witnesses in legal cases, but they never used that handle themselves.

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## buffnut453 (May 23, 2021)

FLYBOYJ said:


> "Anyone who calls themselves "an expert" is a specialist who knows everything about something, and nothing about anything else."



You mean, for example, the fact that a fighter cruising at 300+ mph wouldn't be very effective in roles that required a truly long range like, say, bomber escort?

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## FLYBOYJ (May 23, 2021)

pbehn said:


> The title "expert" is normally conferred on people by others. I have only met two people who were actually legally defined "experts" they had both been called as expert witnesses in legal cases, but they never used that handle themselves.


My dad was a mechanic for 50 years - he hated the term "master mechanic." He always said there's no such thing.

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## Glider (May 23, 2021)

FLYBOYJ said:


> Several things - The P-39N manual I have shows best fuel consumption climb to 25K at 31.2 GPH
> View attachment 624415
> 
> 
> ...



This I find very interesting. P39 in his posts has stated that the P39N had 120 gallons of fuel internally and from the above it seems as if it only had 70 usable gallons which gives even by RAF standards a pretty miserable range.

The only range figures I can find for the Typhoon are :-
Clean - 610 miles
With 45 Gallon Drop Tanks - 1,000 miles
With 2 x 1,000lb bombs - 510 miles

Most economical cruise speed 254 mph

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## Thumpalumpacus (May 23, 2021)

pbehn said:


> The title "expert" is normally conferred on people by others. I have only met two people who were actually legally defined "experts" they had both been called as expert witnesses in legal cases, but they never used that handle themselves.



Expertise should be so apparent that there's no need to proclaim it.

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## fubar57 (May 23, 2021)

The only thing I was an expert at during my prime

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## PAT303 (May 23, 2021)

FLYBOYJ said:


> My dad was a mechanic for 50 years - he hated the term "master mechanic." He always said there's no such thing.



I was a mechanic for 25 years, the moment you think you know everything is the moment something catches you out and makes you look like a fool.

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## PAT303 (May 23, 2021)

P-39 Expert said:


> RAF did have a pretty solid idea for armament: the 20mm cannon, which they went to right after the BoB.
> 
> Biggest drawback with the 30calMG was effective range was only 200yds (AHT).



The Browning .303 had very effective incendiary and AP rounds from start to finish, they were only replaced when the Browning .50 proved their worth, which was after '43.

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## GrauGeist (May 23, 2021)

FLYBOYJ said:


> My dad was a mechanic for 50 years - he hated the term "master mechanic." He always said there's no such thing.


At one point in my mechanic career, I was ASE rated "Master Technician" with "Advanced Level Specialist" certifications (automobile engine, drive-train, body electric, etc., etc.).
Just peices of paper on the wall, honestly. Anyone can take the courses - but what makes a difference is what you do with that knowledge.

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## pbehn (May 23, 2021)

PAT303 said:


> The Browning .303 had very effective incendiary and AP rounds from start to finish, they were only replaced when the Browning .50 proved their worth, which was after '43.


And the weight of 0.5 ammunition in UK was in danger sinking the whole island.

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## pbehn (May 23, 2021)

fubar57 said:


> The only thing I was an expert at during my prime
> 
> View attachment 624430​


You may be able to drink more than me, but you will never get more drunk.

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## FLYBOYJ (May 23, 2021)

I felt like doing some math...

So this is what I come up with, using those 2 charts posted and I used very conservative numbers except for take off weight, I used the fully loaded 8000 pounds, no wind condition to assume IAS will equal ground speed (for simplicity).

Start with 120 gallons (per the expert). Take away 20 gallons for warm up per the chart and you start with *100 gallons.*

Take off at S/L, climb to 25,000 feet - 140 mph indicated, 31.2 gallons used, 29.9 minutes in the air at 140 mph so we traveled *70 miles.*

*68.8 gallons left. *

In the cruise chart there is no data for 25,000' so we'll use 20,000'

Cruise 15 minutes, 160 MPH, 8.75 gallons used - *39 miles*

*60.1 gallons left.*

Combat! 15 minutes. 10 minutes full power, 5 minutes WEP

34.75 gallons used. We'll also assume this was a traveling fight at 300mph - *75 miles*

*25.35 gallons left*

Fight is over, descend down to 3000' (good cruising altitude) descend 1000' per minute at 160 mph 22 minutes, 12. 8 gallons used, *58 miles*

*12.6 gallons left.*

10 gallons reserve, *2.55 gallons left.* At 160 mph you'll burn that up in about 5 minutes,* 40 miles*

Total mission miles with 10 gallons reserve - *282 miles*

*I didn't account for blower setting, auto rich or lean or density altitude, just read the data straight off the charts. Also did not account for flying a pattern and landing. OK folks, check my math!*

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## pbehn (May 23, 2021)

FLYBOYJ said:


> I felt like doing some math...
> 
> So this is what I come up with, using those 2 charts posted and I used very conservative numbers except for take off weight, I used the fully loaded 8000 pounds, no wind condition to assume IAS will equal ground speed (for simplicity).
> 
> ...


That is why it was used for a couple of missions by 4 aircraft across the channel.

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## Greg Boeser (May 23, 2021)

I'm assuming that if there is no figure for a certain altitude for a certain cruise condition, it's because that throttle setting would not permit sustained operation there?

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## FLYBOYJ (May 23, 2021)

Greg Boeser said:


> I'm assuming that if there is no figure for a certain altitude for a certain cruise condition, it's because that throttle setting would not permit sustained operation there?



Yes - the data stops at 20,000 feet so I used those cruise numbers although one page of the manual gives climb data to 25,000'


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## Greg Boeser (May 23, 2021)

Because you can operate at that altitude at max continuous.

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## pbehn (May 23, 2021)

When the P-39 was introduced into Europe what target could it hit? If you damage or destroy French and Belgian infrastructure the Germans just tell the local population to repair it, at their cost. The only important targets are the ports which you yourself need or must pretend you need to keep attention from Normandy, but that was in 1944.


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## FLYBOYJ (May 23, 2021)

Greg Boeser said:


> Because you can operate at that altitude at max continuous.



*At 7500 pounds - *It now matches the 2nd chart

Start with 120 gallons (per the expert). Take away 20 gallons for warm up per the chart and you start with *100 gallons.*

Take off at S/L, climb to 25,000 feet - 150 mph indicated, 35.3 gallons used, 10.8 minutes in the air at 150 mph so we traveled *27 miles.*

*64.7 gallons left.*

In the cruise chart there is no data for 25,000' so we'll use 20,000'

Cruise 15 minutes, 160 MPH, 8.75 gallons used - *39 miles*

*55.95.1 gallons left.*

Combat! 15 minutes. 10 minutes full power, 5 minutes WEP

34.75 gallons used. We'll also assume this was a traveling fight at 300mph - *75 miles*

*21.2 gallons left*

Fight is over, descend down to 3000' (good cruising altitude) descend 1000' per minute at 160 mph 22 minutes, 12. 8 gallons used, *58 miles*

*8.4 gallons left.*

*About 5 minutes of fuel remaining - 13 miles*

*212 miles*

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## GregP (May 23, 2021)

It's like trying to get more pregnant. Tough to do.

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## GregP (May 23, 2021)

Just more fuel for the bonfire ...

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## FLYBOYJ (May 23, 2021)

LET'S DO THE CORSAIR!!! 

237 Gallons

Using max weight per the flight manual 14,200 pounds

Warm up and take off fuel consumption included per the flight manual chart.

Take off at S/L, climb to 25,000 feet - *125 knots indicated, 83 gallons used, 19 minutes in the air at *143.8 mph = *45 miles*

*159 Gallons left*

Cruise 15 minutes, 14.5 gallons at *191mph ( *based on Report No. 6195 April 1, 1943 from Chance Vought. NAVAIR bases charts on endurance) = *47.7 miles*

*144.5 Gallons left*

Combat! 15 minutes. 10 minutes full power, 5 minutes WEP 88 gallons at 380 mph = *94 miles* NOTE: Military power used 275 GPH low blower per my manual (numbers were shown)

*56.5 Gallons left*

Fight is over, descend down to 3000' (good cruising altitude) descend 1000' per minute at 191 mph 22 minutes, 15.9 gallons used, *70 miles*

*40.6 Gallons left*

Minus 10 gallons reserve -

*30.6 Gallons left*

40 minutes left in the air at 191 mph = *127 miles*

*384 miles*

*




*

*



*

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## Thumpalumpacus (May 23, 2021)

FLYBOYJ said:


> *OK folks, check my math!*



That's too much arithmetickin' for this Texan to manage at 9:30 pm. You best find a 7-Eleven to stop at before entering the fray, right? Gas up, and grab an energy-drink while you're at it.

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## buffnut453 (May 24, 2021)

FLYBOYJ said:


> LET'S DO THE CORSAIR!!!
> 
> 237 Gallons
> 
> ...



That's all well and good, Joe....but we all know that, in a couple more pages of this thread, the P-39 will magically be comparable to the F4U Corsair again thanks to P-39Expert's calculations and/or considered opinion.

It's kinda sad that some of us, self included, hope for a different result. Methinks I'm gusting perilously close to the definition of insanity.

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## ThomasP (May 24, 2021)

To be fair, the first ~160 production P-39N-1 were still fitted with the normal P-39 fuel tankage for 120 USgal.


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## Thumpalumpacus (May 24, 2021)

buffnut453 said:


> Methinks I'm gusting perilously close to the definition of insanity.



Or at least the Internet definition of it.


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## Greg Boeser (May 24, 2021)

Those charts are full of data. How is a layman supposed to interpret them? Be nice if someone could start a new thread with a tutorial.
Otherwise a layman may just take the most impressive number from whatever convenient column to prop up his argument.
For example, what is the difference between a combat climb and a ferry climb?

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## FLYBOYJ (May 24, 2021)

buffnut453 said:


> That's all well and good, Joe....but we all know that, in a couple more pages of this thread, the P-39 will magically be comparable to the F4U Corsair again thanks to P-39Expert's calculations and/or considered opinion.
> 
> It's kinda sad that some of us, self included, hope for a different result. Methinks I'm gusting perilously close to the definition of insanity.



Or total debauchery of chart usage. The record goes round and round

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## FLYBOYJ (May 24, 2021)

Greg Boeser said:


> Those charts are full of data. How is a layman supposed to interpret them? Be nice if someone could start a new thread with a tutorial.
> Otherwise a layman may just take the most impressive number from whatever convenient column to prop up his argument.
> For example, what is the difference between a combat climb and a ferry climb?



You have a point but those presented are pretty easy although some data is hidden and is in small type. I think some people take half the data from the chart and then try to use their own formula to make calculations

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## Airframes (May 24, 2021)

When it came to my opinion on the P-39, I used to be indecisive. Now, I'm not sure ...................................

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## Glider (May 24, 2021)

ThomasP said:


> To be fair, the first ~160 production P-39N-1 were still fitted with the normal P-39 fuel tankage for 120 USgal.


And there would have been a reason for reducing it in the rest. Then P39 needs to be clear if the performance figures are with the 120 or 90 US Gal, and prove it of course

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## FLYBOYJ (May 24, 2021)

Glider said:


> And there would have been a reason for reducing it in the rest. Then P39 needs to be clear if the performance figures are with the 120 or 90 US Gal, and prove it of course


When I did those calculations I tried to be as conservative as possible to show minimal fuel consumption so we can determine range, especially for the P-39 but the charts from the flight manual speak for themselves. I wanted to show the source instead of flapping numbers without a mention of fuel consumption. As I was doing the calculations it became apparent that a mission to 25,000' was not the best profile for the P-39

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## buffnut453 (May 24, 2021)

FLYBOYJ said:


> When I did those calculations I tried to be as conservative as possible to show minimal fuel consumption so we can determine range, especially for the P-39 but the charts from the flight manual speak for themselves. I wanted to show the source instead of flapping numbers without a mention of fuel consumption. As I was doing the calculations it became apparent that a mission to 25,000' was not the best profile for the P-39



Heyyy....wait a minute!!! I've just figured out the primary role for the YB-40. It was to escort the P-39. The YB-40 as heavily armed, and could fly at higher altitude to protect the P-39 from being bounced from above. It also had longer operating range so it could loiter over the entirety of the P-39 mission. 

Sounds like a war-winner to me!!!

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## GregP (May 24, 2021)

So, now we know the YB-40 was a Foo Fighter escort of unparalleled capability. I KNEW it was good for SOMETHING. The Flying Fortress is shown below:







The YB-40 is shown below:






Cool!






Some period observations above ...

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## P-39 Expert (May 24, 2021)

FLYBOYJ said:


> Several things - The P-39N manual I have shows best fuel consumption climb to 25K at 31.2 GPH at 30 minutes
> View attachment 624415
> 
> 
> ...


Sorry, but my numbers are not wrong. I did use 16 gallons for warm up and climb instead of 20, I was looking at the P-39Q chart. So deduct 4 gallons if you want. You don't use both the 20gal reserve for warm up AND the fuel from sea level (31.2gal in your example) from the climb data chart. Just the warmup/takeoff/climb to 5000ft. Range includes climb but not descent. Since the pilot is climbing in the direction of the target at 170mph IAS he is effectively cruising at that speed until desired altitude is reached, about 10 minutes. The difference in climb speed and cruising speed for 10 minutes is negligible. Total fuel less allowance for warmup/takeoff/climb less combat reserve less landing reserve gives net fuel. Divide by gallons per hour to get cruising time and multiply by TAS (IAS converted) and that equals range. Everything is on the Flight Operation Instruction Chart you posted. I'm using the 120gal P-39.

If the P-39 and the F4U are used for the same mission then they have to use the same formula and mission profile. Takeoff and climb to 25000ft, cruise at maximum cruise, 20 minutes of combat and cruise back at maximum cruise with a 20 minute reserve for landing. The Navy used a cruise out at 15000ft at V max for max range (182mph) and then cruise back at 1500ft at V max range. That works fine for over water flights where the chance of encountering the enemy is small, but that won't work at all for escort or interception missions over land as the AAF did. Cruising out at 15000ft or cruising back at 1500ft would be suicidal.


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## P-39 Expert (May 24, 2021)

FLYBOYJ said:


> I felt like doing some math...
> 
> So this is what I come up with, using those 2 charts posted and I used very conservative numbers except for take off weight, I used the fully loaded 8000 pounds, no wind condition to assume IAS will equal ground speed (for simplicity).
> 
> ...


Please see my post #1503.


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## P-39 Expert (May 24, 2021)

FLYBOYJ said:


> *At 7500 pounds - *It now matches the 2nd chart
> 
> Start with 120 gallons (per the expert). Take away 20 gallons for warm up per the chart and you start with *100 gallons.*
> 
> ...


Please see my post #1503.


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## P-39 Expert (May 24, 2021)

FLYBOYJ said:


> LET'S DO THE CORSAIR!!!
> 
> 237 Gallons
> 
> ...


Please see my post #1503.


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## GregP (May 24, 2021)

In Post 1503, you say cruising out and returning at 15,000 feet would be suicidal. That's EXACTLY why USN and USAAF airplanes are different ... they have differing requirements and different missions. So, there is no real point in comparing them for missions since they do different things. Hence, two different services. 

You made the point perfectly. Navy/Marine and Air Corps airplanes were not going to do the same missions very often, so there is no point in comparing the two.

So don't. Compare instead against aircraft that would be flying the same missions.


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## P-39 Expert (May 24, 2021)

GregP said:


> In Post 1503, you say cruising out and returning at 15,000 feet would be suicidal. That's EXACTLY why USN and USAAF airplanes are different ... they have differing requirements and different missions. So, there is no real point in comparing them for missions since they do different things. Hence, two different services.
> 
> You made the point perfectly. Navy/Marine and Air Corps airplanes were not going to do the same missions very often, so there is no point in comparing the two.
> 
> So don't. Compare instead against aircraft that would be flying the same missions.


I said cruising back at 1500ft, not 15000ft. 

It's the only way to compare a land based AAF plane to a land based Navy carrier plane if they were flying the same missions.


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## GregP (May 24, 2021)

There is really no point in comparing Naval and non-Naval aircraft for mission range. 

The only time they are likely to tangle is if land planes attack a carrier task force. If that DOES happen, the range is immaterial since the carrier planes are essentially operating very close to home and the land planes have to have whatever range is required to attack the carriers and get back. The only performance characteristics that matter in that case are performance numbers such as turn. climb, speed, and armament, not range.

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## fubar57 (May 24, 2021)

GregP
Until a month ago I was unaware that there was a B-24 trialled as a gunship as well, the XB-41





PUBLIC DOMAIN​

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## FLYBOYJ (May 24, 2021)

P-39 Expert said:


> Sorry, but my numbers are not wrong. I did use 16 gallons for warm up and climb instead of 20, I was looking at the P-39Q chart. So deduct 4 gallons if you want. You don't use both the 20gal reserve for warm up AND the fuel from sea level (31.2gal in your example) from the climb data chart.


*WRONG - read the chart!!*!!

*DOES IT SAY THE 20 MINUTE WARM UP IS INCLUDED?!?!?*

*no!*

I'll blow it up for you






*"TIME FROM SL" FUEL FROM SL"*

*SL = SEA LEVEL - IT'S THAT SIMPLE!!!!*

*IT'S CLEARLY SHOWN THAT IF CLIMB FROM SEA LEVEL TO 25000 FEET AT 140 INDICATED, DEPENDING ON CLIMB ANGLE AND POWER USED, YOU'RE GOING TO REACH 25000 FEET IN EITHER 13.9 MINUTES OR 29.9 MINUTES AND BURN EITHER 39.9 GALLONS OR 31.2 GALLONS, CLIMBING 800' PER MINUTE OR 600' PER MINUTE! I USED NUMBERS THAT GAVE THE BEST CLIMB WHILE USING THE LEAST AMOUNT OF FUEL (AND GOD, THE P-39 NEEDED IT)*

(AND THIS IN A NO WIND, STANDARD ATMOSPHERIC DAY)




P-39 Expert said:


> Just the warmup/takeoff/climb to 5000ft. *Range includes climb but not descent*.



ARE YOU SERIOUS????

*WHERE DOES IT SAY THAT?!?!?! YOU'RE STILL BURNING FUEL IN DESCENT OR ARE YOU GOING TO TELL ME YOU TURN THE MOTOR OFF?!?!?*




P-39 Expert said:


> Since the pilot is climbing in the direction of the target at 170mph IAS he is effectively cruising at that speed until desired altitude is reached, about 10 minutes.



*NOW YOU'RE ADDING YOUR OWN INTERPETATION. IS IT VX OR VY OR DO EVEN KNOW WHAT THAT MEANS?*



P-39 Expert said:


> The difference in climb speed and cruising speed for 10 minutes is negligible. Total fuel less allowance for warmup/takeoff/climb less combat reserve less landing reserve gives net fuel.


WHERE DOES IT SAY TO DO THAT?!?


P-39 Expert said:


> Divide by gallons per hour to get cruising time and multiply by TAS (IAS converted) and that equals range. Everything is on the Flight Operation Instruction Chart you posted. I'm using the 120gal P-39.



AGAIN, THIS SHOWS YOU DON'T KNOW WHAT YOU'RE TALKING ABOUT!!! *HOW ARE YOU GOING TO GET TAS??? * *YOU DON'T KNOW PRESSURE ALTITUDE AND TEMPERATURE IN THIS EXAMPLE!!!! *

*IT WAS OBVIOUS THIS WAS HYPOTHETICAL SO TEMPS AND PRESSURE ALTITUDE WAS NOT FACTORED IN,*




P-39 Expert said:


> If the P-39 and the F4U are used for the same mission then they have to use the same formula and mission profile.



AND THAT WAS CLEARLY DONE BASED ON COMPARING THE TWO AIRCRAFT TO AN AAF INTERCEPT MISSION!!!! I added the 3000' cruise to actually give a nudge to the P-39!!!!


P-39 Expert said:


> Takeoff and climb to 25000ft, cruise at maximum cruise, 20 minutes of combat and cruise back at maximum cruise with a 20 minute reserve for landing. The Navy used a cruise out at 15000ft at V max for max range (182mph) and then cruise back at 1500ft at V max range. That works fine for over water flights where the chance of encountering the enemy is small, but that won't work at all for escort or interception missions over land as the AAF did. Cruising out at 15000ft or cruising back at 1500ft would be suicidal.



NOW YOU'RE ADDING HYPOTHETICAL SITUATIONS - I POSTED WHAT BOTH AIRCRAFT WILL DO IN THE SAME SITUATION AND SHOWED EXACTLY HOW IS DONE AND EVEN GAVE A "NUDGE" TO THE P-39. NO WHERE *DO YOU SHOW FUEL CONSUMPTION BASED ON THE CHART DATA!* IT'S QUITE CLEAR BY THE DATA CLEARLY SHOWN HOW THE P-39 WAS OUT-PERFORMED!!!!

*ONCE AGAIN, YOU'RE MIS-INTERPERTING THE CHART, JUST LIKE YOU DID THE WEIGHT AND BALANCE CHART!!!*

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## wuzak (May 24, 2021)

P-39 Expert said:


> Takeoff and climb to 25000ft, cruise at *maximum cruise*, 20 minutes of combat and cruise back at maximum cruise with a 20 minute reserve for landing.



Is that because there was no other cruise setting that worked at 25,000ft?


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## FLYBOYJ (May 24, 2021)

wuzak said:


> Is that because there was no other cruise setting that worked at 25,000ft?



Or the test data wasn't done or wasn't available to put in the flight manual.


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## FLYBOYJ (May 24, 2021)

"*Range includes climb but not descent"*

Has anyone else ever heard of that?


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## FLYBOYJ (May 24, 2021)

F4U Manual, take off, climb and landing chart - 






YOU DO WHAT THE CHART TELLS YOU!


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## GregP (May 24, 2021)

Hey Fubar57,

There was also a B-24 with a B-17 nose grafted on:






You just never know what they will come up with, such as:






The Leduc 0.10 is certainly a strange bird. Ask the erstwhile pilot above!. If someone was attacking you from the rear, how would you know it was anything but an engine failure? Certainly not by turning around and looking over the tail!

Then we have a Russian candidate:






This adds fuel to the adage that, "If it is weird, it is British; if it is ugly, it is French; if it is weird AND ugly, it is Russian." Talk about a flying tank!

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## FLYBOYJ (May 24, 2021)

P-39 Expert said:


> You don't use both the 20gal reserve for warm up AND the fuel from sea level (31.2gal in your example) from the climb data chart. Just the warmup/takeoff/climb to 5000ft.



Gee - lookie here...






and smack in the middle of the cruise charts it says...






Why is that??? 

EDIT!

Because on the climb chart it says this:






*So I'll stand to be correct but let's look at numbers;*

90 gallons internal, climb to 25K 31.2 gallons 20 for warm up and take off, 11.2 for climb

90 - 31.2 = 58.8 gallons fuel left at 25K

You made a claim that internal fuel was 120 gallons, ok...

120 - 31.2 = 88.8 gallons.

I'll give you the benefit of the doubt, that gives an extra 20 gallons. Where do you want to use it?

Suppose we put it in the cruise home at 3000' - according to the cruise chart that buys you up to 120 miles @ 217mph cruise, so now the mission profile I completed goes to 402 miles with no reserve

BUT

If the internal fuel is 90 gallons, you lose 10 gallons which puts you at 342 miles with no reserve.

EDIT - The flight manual that I have for the P-39N shows 90 gallons in the W&B 87 useable.


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## BiffF15 (May 24, 2021)

Interesting. Also remember you are doing a single ship. Add more aircraft, use more fuel for ground ops, takeoff, and rejoin. The more you add, the more fuel you use, and the shorter the range.

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## FLYBOYJ (May 24, 2021)

BiffF15 said:


> Interesting. Also remember you are doing a single ship. Add more aircraft, use more fuel for ground ops, takeoff, and rejoin. The more you add, the more fuel you use, and the shorter the range.


From our resident fighter pilot, thank you Biff!

BTW - I went back and looked at the numbers and in the descent for the P-39 coming down from 25K down to 3000' I could have used a best fuel consumption of 32 GPH at 215 mph indicated. Would have added an extra 20 miles but used less than a half gallon more.

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## Milosh (May 24, 2021)

Actual combat radius is approx. 1/3 of range. Doesn't matter what a/c.


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## BiffF15 (May 24, 2021)

FLYBOYJ said:


> From our resident fighter pilot, thank you Biff!
> 
> BTW - I went back and looked at the numbers and in the descent for the P-39 coming down from 25K down to 3000' I could have used a best fuel consumption of 32 GPH at 215 mph indicated. Would have added an extra 20 miles but used less than a half gallon more.



The wingmen always use more fuel. And if he is a less experienced wingman, he will use even more of it.

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## FLYBOYJ (May 24, 2021)

Milosh said:


> Actual combat radius is approx. 1/3 of range. Doesn't matter what a/c.



Errr, I don't know, that's subjective. Many major missions were planned and flown right to the edge of performance limits. Gotta be bit more specific


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## special ed (May 24, 2021)

The amazon ads at the bottom of this thread are "The neverending Story II: The Next Chapter" and "The Neverending Story Season 1". Do they know something? Should we be concerned?

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## FLYBOYJ (May 24, 2021)

and along with that

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## Shortround6 (May 24, 2021)

At the back of AHT there are several charts for the combat radius of action for the P-38, the P-47 and the P-51.

The conditions are very clearly spelled out. This is a general information chart/s and not to be used for specific mission planning. 

A. warm up and take off equivalent to 5 minutes at normal rated power. 
B. Climb to 25,000ft at Normal rated power (distance covered in climb is NOT included in radius)
C. cruise out at 25,000ft and 210 I.A.S.
D. Drop external tanks before entering combat. 
E. Combat 5 minutes at War Emergency Power and 15 minutes at Military power.
F, Cruise back at 25,000ft and 210 I.A.S.
G. No account is taken of decreased fuel consumption during decent.
H. Allowance is made for 30 minutes reserve at minimum cruise power.
I. No allowance is made for formation flight or for evasive action other than the the 20 minutes combat. 

The P-38J with 410 gallons internal is rated at 275 miles radius.
The P-47 with 305 gallons internal is rated at 125 miles radius.
P-47 with 370 gallons internal is rated at 225 miles radius.
P-51 with 184 gallons internal is rated at 150 miles radius.
P-51 with 269 gallons internal is rated at 375 miles radius. 

Now the P-39 falls into a rather strange hole. It can meet the 25,000ft and 210I.A.S cruise with a small speed margin if running clean if it runs at near max continuous power. 
The P-39Q-1 had about a 15mph margin on the cruise speed.
_HOWEVER _the P-39 Q-1 fails to meet the desired cruise speed at 25,000ft by around 45mph if carrying a 75 gallon drop tank according to the chart in the Manual. 

Without the drop tank the P-39Q (even with 120 gallons ) has a combat radius of about 65 miles. 

9 gallons for warm up per the above conditions. Normal rated is the same as max continuous. 
25 gallons for Climb to 25,000ft (took out the 9 gallons for warm up)
15 gallons for 30 minute reserve (assumed 30 gallons an hour for minimum, charts show low 30 gallons an hour range for low altitude) 

this leaves 71 gallons. I figured 26 gallons for the combat allowance. this was done by estimating that the Military power used about 25-26% more fuel than max continuous. 
P-39 supercharger cannot come close to providing enough air at 25,000ft for anything like full military power at the lower altitudes so using those consumption figures is useless. 

Which leaves 45 gallons for the range which the chart for a clean P-39Q at 25,000ft is about 130 miles at 25,000ft and 330mph true which does not line up with fuel/speed figures at the bottom. Assuming the 330mph speed needs 62 gallons and hour you get about .75 hours from 45 gallons or 247.5 miles of_ range_ or about 125 miles of radius. Backing off just bit in speed will get you a few more miles. 

Now the problem is can the P-39N/Q actually fight at 25,000ft and not just fly in a straight line. the engine is lucky to make 770 hp at 25,000ft using military power 3000rpm and full throttle) WEP disappeared below 15,000ft.

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## FLYBOYJ (May 24, 2021)

Shortround6 said:


> At the back of AHT there are several charts for the combat radius of action for the P-38, the P-47 and the P-51.
> 
> The conditions are very clearly spelled out. This is a general information chart/s and not to be used for specific mission planning.
> 
> ...


SR - a lot of this coincides (or comes close to) my numbers taken from the manual with no temp or DA adjustment.

Example - you show:

9 gallons for warm up per the above conditions. Normal rated is the same as max continuous.
25 gallons for Climb to 25,000ft (took out the 9 gallons for warm up)

34 gallons.

from the chart;






Fuel includes warm up and take off allowance

Of course we have variance with a Vx or Vy climb


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## FLYBOYJ (May 24, 2021)

Shortround6 said:


> Which leaves 45 gallons for the range which the chart for a clean P-39Q at 25,000ft is about 130 miles at 25,000ft and 330mph true *which does not line up with fuel/speed figures at the bottom. *Assuming the 330mph speed needs 62 gallons and hour you get about .75 hours from 45 gallons or 247.5 miles of_ range_ or about 125 miles of radius. Backing off just bit in speed will get you a few more miles.



Noticed that as well



Shortround6 said:


> Now the problem is can the P-39N/Q actually fight at 25,000ft and not just fly in a straight line. the engine is lucky to make 770 hp at 25,000ft using military power 3000rpm and full throttle) WEP disappeared below 15,000ft.



Thus the reason for no cruise data in the flight manual at 25,000'


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## FLYBOYJ (May 25, 2021)

Shortround6 said:


> E. Combat 5 minutes at War Emergency Power and 15 minutes at Military power.
> I figured 26 gallons for the combat allowance. this was done by estimating that the Military power used about 25-26% more fuel than max continuous.








I come up with 38.74 gallons based on this chart although shown for 14 & 15.5K


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## P-39 Expert (May 25, 2021)

FLYBOYJ said:


> "*Range includes climb but not descent"*
> 
> Has anyone else ever heard of that?


wwiiaircraftperformance.org, F4U-1 Airplane Characteristics and Performance. Same for the F6F. Makes sense, pilot is climbing in the direction of the target as he is gaining altitude. Doesn't include descent since there is a reserve for landing included in calculations.


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## Shortround6 (May 25, 2021)

FLYBOYJ said:


> SR - a lot of this coincides (or comes close to) my numbers taken from the manual with no temp or DA adjustment.
> 
> Example - you show:
> 
> ...



I low balled it a bit. 
For the combat allowance I figured that the Military power at 25,000ft would be in proportion to the max continuous power. 
I used 104 gallons per hour compared to 140 gallons an hour for an average between take-off and power at 15,500ft. 
Then I multiplied that factor times the 62 gallons per hour of the max continuous at 25,000ft. A bit rough perhaps. 

One does have to interpret these pilots manual charts sometimes. The one you are listing for the N seems to missing a line. Or has some confusing terminology.
The line that is labeled Maximum emergency power is actually military power as the note at the bottom corrects. 

The chart from the P-39Q manual has the correct lines in the chart but then stops at "max cruise" which is identical to the economical maximum line in the chart for the N with both planes using the V-1710-85 engine. 

We can fudge figures a gallon or two here and there but nothing is going to make the P-39 even a medium range fighter. 

Our expert took the 62 gph figure at 25,000ft and ran with it.
Why does the P-39 burn 57% of the fuel at 25,000ft that it does at 15,000ft with the same rpm (2600) and throttle setting ( full throttle) ?
Because it's supercharger cannot deliver enough air at that altitude and rpm to burn any more fuel. Not because the P-39 was some marvel of fuel efficiency. 

A 7000lb airplane trying to fight at 25,000ft with 800 hp is going to be at a real disadvantage no matter how fast it can fly in a straight line. 
The P-39 has by far the worst power to weight ratio of any of the possible American fighters at those altitudes. 
The F4U-1 even at 12,000lbs has a power to weight ratio of 1 hp for every 7.74 lbs (assuming 1550hp at 15,000ft since it has 1650 at 23,000ft with ram)


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## Shortround6 (May 25, 2021)

P-39 Expert said:


> wwiiaircraftperformance.org, F4U-1 Airplane Characteristics and Performance. Same for the F6F. *Makes sense, pilot is climbing in the direction of the target as he is gaining altitude.* Doesn't include descent since there is a reserve for landing included in calculations.



Great idea if you have 1-3 fighters going to meet up with 1-4 bombers. 
Horrible idea if you have an entire fighter group meeting up with a bomber group under real life conditions. 
You have to get the fighters off the ground in sequence, form up your flight, squadron and group formations, then fly to the rendezvous location where the bombers may be on time, or early or late depending on how their take-off and forming up operations went. 

Counting on flying to the direction of the target as soon as you are wheels up means your fighter group is strung out for miles in very small clusters as you enter enemy airspace. First aircraft off the ground may be 10 or more minutes ahead of the last planes.

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## FLYBOYJ (May 25, 2021)

P-39 Expert said:


> wwiiaircraftperformance.org, F4U-1 Airplane Characteristics and Performance. Same for the F6F. Makes sense, pilot is climbing in the direction of the target as he is gaining altitude. Doesn't include descent since there is a reserve for landing included in calculations.


But he is still climbing and burning fuel!!!! This is NOT the same as a cruise setting! Reserve fuel IS NOT used for descent and landing!


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## FLYBOYJ (May 25, 2021)

Shortround6 said:


> I low balled it a bit.
> For the combat allowance I figured that the Military power at 25,000ft would be in proportion to the max continuous power.
> I used 104 gallons per hour compared to 140 gallons an hour for an average between take-off and power at 15,500ft.
> Then I multiplied that factor times the 62 gallons per hour of the max continuous at 25,000ft. A bit rough perhaps.
> ...



Agree with all -

Later today I'm going to do some calculations straight out of the flight manual for the P-39N. Take off at S/L and climb immediately to 20,000 feet. For the climb chart I'm going to "interpulate" a climb to 20,000' (because the climb chart goes from 15K to 25K). I'll then plug in a 15 minute cruise at 20K followed by "combat" at max power for 10 minutes. After that I'll show at 20,000' what fuel is left and the maximum range that is left.

No wind, standard pressure so DA and PA are equal so we are perfectly clear!


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## buffnut453 (May 25, 2021)

P-39 Expert said:


> wwiiaircraftperformance.org, F4U-1 Airplane Characteristics and Performance. Same for the F6F. Makes sense, pilot is climbing in the direction of the target as he is gaining altitude. *Doesn't include descent since there is a reserve for landing included in calculations*.



No, no, NO. The reserve is NOT to cover descent and landing. The reserve is there in case the pilot needs to go around or find an alternate airfield. No pilot should be relying on his/her reserve as the means to get into their primary airfield.

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## FLYBOYJ (May 25, 2021)

buffnut453 said:


> No, no, NO. The reserve is NOT to cover descent and landing. The reserve is there in case the pilot needs to go around or find an alternate airfield. No pilot should be relying on his/her reserve as the means to get into their primary airfield.



"Pilot 101". Reserves usually 30 minutes VFR and 45 minutes IFR, used today in GA and I think this was a norm during WW2


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## BiffF15 (May 25, 2021)

buffnut453 said:


> No, no, NO. The reserve is NOT to cover descent and landing. The reserve is there in case the pilot needs to go around or find an alternate airfield. No pilot should be relying on his/her reserve as the means to get into their primary airfield.



“Reserve fuel” is not a reserve of fuel if you are planning on using it to accomplish your mission. If everything goes as planned it should still be in the tanks at engine shutdown.

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## DerAdlerIstGelandet (May 25, 2021)

buffnut453 said:


> No, no, NO. The reserve is NOT to cover descent and landing. The reserve is there in case the pilot needs to go around or find an alternate airfield. No pilot should be relying on his/her reserve as the means to get into their primary airfield.



You mean I have been doing it all wrong? I thought the sputtering of my engine made me sound cooler when I go for my $100 burgers.

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## Peter Gunn (May 25, 2021)

Wait... a P-39 _fighting_ at 25,000 feet... 

...


BWAHAHAHAHAHAHHAHAHA

You're kidding right? Right?

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## Thumpalumpacus (May 25, 2021)

Peter Gunn said:


> Wait... a P-39 _fighting_ at 25,000 feet...
> 
> ...
> 
> ...



Fighting for breath, maybe?

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## GrauGeist (May 25, 2021)

DerAdlerIstGelandet said:


> You mean I have been doing it all wrong? I thought the sputtering of my engine made me sound cooler when I go for my $100 burgers.


And here we thought the sputtering was just showing off, trying to sound like a WWI fighter to impress everyone!


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## buffnut453 (May 25, 2021)

GrauGeist said:


> And here we thought the sputtering was just showing off, trying to sound like a WWI fighter to impress everyone!



You mean like this?

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## DerAdlerIstGelandet (May 25, 2021)

GrauGeist said:


> And here we thought the sputtering was just showing off, trying to sound like a WWI fighter to impress everyone!



That is what I was aiming for. Gotta make that lycoming sound like a Cyclone returning from a long bombing mission over Schweinfurt in a Hollywood movie.

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## FLYBOYJ (May 25, 2021)

OK some numbers (I know all of you think this is so exciting!!!!)

*Take off, climb to 20,000' go to best cruise for 15 minutes, Max power or War Emergency for 10 minutes, show remaining fuel and remaining range*

*No wind, standard pressure so DA and PA are equal so for this calculation IAS = TAS*

P-39N-0-BE, straight from the Flight Manual

No external fuel tank used

Weight and balance chart show the aircraft with *87 gallons, 7500 pounds*.

"Interpolate" the climb chart for 20,000' (Military)

Speed - 155mph, 1900FPM, time to 20K 8.2 minutes, fuel burn *33.8 gallons*

I did use a climb gradient calculator to show distance in the climb to 20,000 feet which was *28.2 miles*

*SM per 1000' = 1.41 x 20 = 28.2*






Miscellaneous Aviation Calculations / E6B Emulator

87gallons - 33.8 = *53.2 gallons left after climb.*

"Max Range" on Flight Operation Instruction Sheet @ 20,000' shows 35 GPH at 160 MPH indicated.

Fuel used - 8.7 Gallons, miles flown at this leg = *40 miles*

53.2 - 8.7cruise fuel used = *44.5 gallons remaining*

Enter Combat, I'll just use "military power" fuel flow indicated on the Flight Operation Instruction Sheet NOTE - this setting is shown at 14,500' so it may a little lower at 20K






*147 Gallons Per Hour*

*10 minutes = 24.5 gallons*

44.5 - 24.5 gallons = *20 gallons left.*

According to the Flight Operation Instruction Sheet, column V "MAX RANGE" 20 gallons get you *125 MILES REMAINING *

*



*



*____________________________________________________________________________________________________________________ *

_Let's do the Corsair!_

F4U-1 R2800-8VV

No external fuel tank used

Ref "TAKEOFF CLIMB AND LANDING CHART"

Aircraft gross weight 14,200 pounds 237 Gallons fuel.

Climb to 20,000 feet

130 Knots (150 mph)

1100 Feet Per Minute

13 minutes to 20,000 feet

66 gallons used






Climb gradient calculator, at 150 mph we flew *45.4 miles* (2.27 sm/1000' x 20)

237 - 66 = *171 GALLONS REMAINING*

*CRUISE FOR 15 MINUTES*

SPECIFIC ENGINE FLIGHT CHART

At 20,000 feet "Minimum Fuel Consumption" 53 gallon per hour.

Earlier we came up with cruising speeds between 180 and 191 so I'll go with 186 mph.

FUEL USED - 13.2

*MILES FLOWN - 46.5*

171 - 13.2 = *157.8 GALLONS REMAINING*


Enter Combat, ref SPECIFIC ENGINE FLIGHT CHART

War Emergency at Auto Lean at 20,000' = *245 GPH*

*245/60= 4.08 GPM, 40.83 gallons used in 10 minutes*

*157.8 - 40.83 = 116.97 gallons left*

SPECIFIC ENGINE FLIGHT CHART

At 20,000 feet "Minimum Fuel Consumption" 53 gallon per hour.

Earlier we came up with cruising speeds between 180 and 191 so I'll go with 186 mph.

116.97/ 53 = 2.20 hours range @ 186 mph =* 409 MILES REMAINING*

*



*



Check my math!

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## SaparotRob (May 25, 2021)

You forgot to carry the three.

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## gumbyk (May 25, 2021)

That P-39 profile looks fairly close to a Soviet one. Not enough range for pilots to defect, but just enough to protect Mother Russia...

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## P-39 Expert (May 25, 2021)

FLYBOYJ said:


> *WRONG - read the chart!!*!!
> 
> *DOES IT SAY THE 20 MINUTE WARM UP IS INCLUDED?!?!?*
> 
> ...


Please allow me to clarify the Flight Operation Instruction Chart (range chart) for you. First of all none of the figures on the Take Off, Climb & Landing chart are used to calculate range. The Fuel From Sea Level numbers have nothing to do with range, unless somehow mission profile called for a climb to cruising altitude while remaining directly over your base before vectoring to target. Highly unlikely. And it takes hardly any time for a squadron to form up. Per Edwards Park in "Angels Twenty" (factual account of combat over and around Port Moresby, NG) they took off two at a time with the first group making a wide swing vectoring to the target. Each of the seven remaining pairs took off and made a slightly narrower vector, so that the eighth (last pair) made a narrow swing to target and had already caught up with the rest of the squadron. Climb to altitude on course to target.

The range chart is all the pilot needed to plan a mission. To compute range for a mission the allowance for warm-up, takeoff and climb to 5000ft (20gal for P-39N) was deducted from total fuel then that net fuel was divided by gallons per hour and multiplied by TAS (not IAS). That's how all the ranges in each column are computed. For example look at column III at 15000ft. 70net gal divided by 67GPH X 300 TAS (242 IAS) = 313miles. The graph shows 300miles but the actual miles were rounded down a little as a safety factor. Same for all the columns at all altitudes (except column I). Gallons divided by GPH X TAS = range. The Fuel from Sea Level on the Take off, Climb and Landing Chart was not used since it already included the 20gal allowance for Warmup, Takeoff and Climb to 5000ft and didn't account for miles gained toward the target during climb.

To get combat range simply deduct the 20min combat reserve and 20 minute reserve for landing in addition to the 20gal reserve for takeoff. To get combat radius take half of the combat range. The reserves could vary if you wanted a longer combat or landing reserve.

The range figures for column I (max cont. power/normal power) vary widely depending on what altitude is used. Right above the range figures in column I it says "At 12000ft Only" meaning the range figure is accurate only at 12000ft. This is because the gallons per hour (GPH) vary from about 100GPH up to 15000ft and then reduce steadily to only 62GPH at 25000ft. So range at 25000ft would be 70gallons divided by 62GPH X 350mph TAS (233mph IAS at 25000ft) = 395mi instead of the 210mi shown on the chart. This is the result of lower GPH coupled with higher TAS at 25000ft than at 12000ft. The other columns II through V show what throttle/propeller/altitude settings will result in the range for that column. Column I fixes the power setting at max. continuous (2600rpm) so the GPH and TAS will vary significantly as altitudes increase. Naturally I prefer to use 120gallons internal instead of the 88. 

As to whether the P-39N will fight at 25000ft, the cruising speed in column I was 350mph (233 IAS), the top speed was 370mph and the rate of climb (clean) was 1950fpm per the Wright Field performance tests. Climb at 25000ft was better than any P-40, P-38F/G, P-47, P-51A, F4U, F6F, Zero, Ki-43 or Typhoon in 1943. About the same as a Me109G. But not nearly as good as the Spitfire IX. P-39N was certainly competitive in 1943.


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## GrauGeist (May 25, 2021)

P-39 Expert said:


> Please allow me to clarify the Flight Operation Instruction Chart (range chart) for you.


Better take notes, Joe - it might come in handy someday if you ever become a pilot.

Oh...wait...

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## FLYBOYJ (May 25, 2021)

P-39 Expert said:


> Please allow me to clarify the Flight Operation Instruction Chart (range chart) for you. First of all none of the figures on the Take Off, Climb & Landing chart are used to calculate range. The Fuel From Sea Level numbers have nothing to do with range, unless somehow mission profile called for a climb to cruising altitude while remaining directly over your base before vectoring to target. Highly unlikely. And it takes hardly any time for a squadron to form up. Per Edwards Park in "Angels Twenty" (factual account of combat over and around Port Moresby, NG) they took off two at a time with the first group making a wide swing vectoring to the target. Each of the seven remaining pairs took off and made a slightly narrower vector, so that the eighth (last pair) made a narrow swing to target and had already caught up with the rest of the squadron. Climb to altitude on course to target.
> 
> The range chart is all the pilot needed to plan a mission. To compute range for a mission the allowance for warm-up, takeoff and climb to 5000ft (20gal for P-39N) was deducted from total fuel then that net fuel was divided by gallons per hour and multiplied by TAS (not IAS). That's how all the ranges in each column are computed. For example look at column III at 15000ft. 70net gal divided by 67GPH X 300 TAS (242 IAS) = 313miles. The graph shows 300miles but the actual miles were rounded down a little as a safety factor. Same for all the columns at all altitudes (except column I). Gallons divided by GPH X TAS = range. The Fuel from Sea Level on the Take off, Climb and Landing Chart was not used since it already included the 20gal allowance for Warmup, Takeoff and Climb to 5000ft and didn't account for miles gained toward the target during climb.
> 
> ...



You're all over the place as usual - Because this is a simulation and we don't know outside air temp and pressures, you cannot accurately calculate TAS!!!!

Reserve fuel IS NOT part of (or should be part of) the flown mission profile, mentioned by 2 other pilots, one happens to be a former F-15 driver. It's required should you you have an issue, 30 mins for VFR flight 45 mins for instrument flight.

ShortRound spelled it out in his previous post (1525)

*"Without the drop tank the P-39Q (even with 120 gallons ) has a combat radius of about 65 miles"*

Refer to post 1543 please. I spelled everything out including the basis for my figures, and manual references, something you seem to avoid -

Oh and I'll stand to be corrected if a gross error is found by you or anyone else


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## buffnut453 (May 25, 2021)

P-39 Expert said:


> Please allow me to clarify the Flight Operation Instruction Chart (range chart) for you. First of all none of the figures on the Take Off, Climb & Landing chart are used to calculate range. The Fuel From Sea Level numbers have nothing to do with range, unless somehow mission profile called for a climb to cruising altitude while remaining directly over your base before vectoring to target. Highly unlikely. And it takes hardly any time for a squadron to form up. Per Edwards Park in "Angels Twenty" (factual account of combat over and around Port Moresby, NG) they took off two at a time with the first group making a wide swing vectoring to the target. Each of the seven remaining pairs took off and made a slightly narrower vector, so that the eighth (last pair) made a narrow swing to target and had already caught up with the rest of the squadron. Climb to altitude on course to target.
> 
> The range chart is all the pilot needed to plan a mission. To compute range for a mission the allowance for warm-up, takeoff and climb to 5000ft (20gal for P-39N) was deducted from total fuel then that net fuel was divided by gallons per hour and multiplied by TAS (not IAS). That's how all the ranges in each column are computed. For example look at column III at 15000ft. 70net gal divided by 67GPH X 300 TAS (242 IAS) = 313miles. The graph shows 300miles but the actual miles were rounded down a little as a safety factor. Same for all the columns at all altitudes (except column I). Gallons divided by GPH X TAS = range. The Fuel from Sea Level on the Take off, Climb and Landing Chart was not used since it already included the 20gal allowance for Warmup, Takeoff and Climb to 5000ft and didn't account for miles gained toward the target during climb.
> 
> ...



I'd really love to hear what qualifications you have to make these comments given that you're directly contradicting qualified pilots, including a former F-15 driver. Or do you know better than them?

The whole reason we keep going round and round on this ridiculous topic is because you steadfastly refuse to accept anyone else's inputs. You either ignore them (e.g. the reference to "useless" 30 cal machine guns) so you can repeat your false claims later, or, as per this latest post, you entirely misinterpret aircraft performance documentation. 

The members of this forum include a great many qualified pilots, aeronautical engineers, warbird restorers, published historians, and a great many other inter-related fields. 

So...please enlighten us. What, exactly, are your qualifications and experience levels? From my perspective, you're talking nonsense. For the record, I have a MS in aerospace systems, 20 years air force service, have been a qualified pilot, a published author on aviation history, and now am a systems engineer...and I'm far less qualified than many on this forum. They teach me new things every day. In order to be taught, one has to be willing to listen and learn. You seem unwilling to exercise those two traits.

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## pbehn (May 25, 2021)

Milosh said:


> Actual combat radius is approx. 1/3 of range. Doesn't matter what a/c.





FLYBOYJ said:


> Errr, I don't know, that's subjective. Many major missions were planned and flown right to the edge of performance limits. Gotta be bit more specific


It is approximately true for planes on internal fuel, simply because the amount of fuel you have to allow as a worst case for start up, take off and climb followed by form up of the fighter squadron and form up with the bomber group. Even the internal fuel of the original P-51 doesnt change that hugely. On the Schweinfurt raid Spitfires took the bombers to the coast and P-47 as far as the Belgian border. Now the Spitfire was short ranged but not THAT short. The P-51 had about 80 US gallons more, so 40 gallons there and 40 gallons back doesnt get you far into Germany from the Belgian coast. When you add the extra fuselage tank and external tanks things change dramatically, ut then it became a complicated mix of distances at cruising speed, time "on station" weaving or circling with the bombers, an allowance for combat and then getting back home. There are two "contingencies" that as far as I can see were never built into calculations. One was the carb. overflow system draining back to the main tank. The other is they didnt actually have to get "home" to their home base in UK, there were emergency landing strips on the coast at Manston and Woodbridge.

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## Greg Boeser (May 25, 2021)

Nobody climbed directly toward the target when taking off. And just what the hell are you doing flying off with out the rest of your formation? Standard practice was to take off, circle the field while the rest of your flight formed up, then when all elements of the formation were in place, climb to cruise altitude. If you are escorting bombers you need to throttle back to avoid separating from your charges.

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## FLYBOYJ (May 25, 2021)

Greg Boeser said:


> Nobody climbed directly toward the target when taking off. And just what the hell are you doing flying off with out the rest of your formation? Standard practice was to take off, circle the field while the rest of your flight formed up, then when all elements of the formation were in place, climb to cruise altitude. If you are escorting bombers you need to throttle back to avoid separating from your charges.


Actually I calculated that just to show performance numbers, but I totally hear you. And in the Real world we would have calculated for atmospheric conditions to include “density altitude and true airspeed“


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## Shortround6 (May 25, 2021)

P-39 Expert said:


> The range chart is all the pilot needed to plan a mission. To compute range for a mission the allowance for warm-up, takeoff and climb to 5000ft (20gal for P-39N) was deducted from total fuel then that net fuel was divided by gallons per hour and multiplied by TAS (not IAS). That's how all the ranges in each column are computed. For example look at column III at 15000ft. 70net gal divided by 67GPH X 300 TAS (242 IAS) = 313miles. The graph shows 300miles but the actual miles were rounded down a little as a safety factor. Same for all the columns at all altitudes (except column I). Gallons divided by GPH X TAS = range. The Fuel from Sea Level on the Take off, Climb and Landing Chart was not used since it already included the 20gal allowance for Warmup, Takeoff and Climb to 5000ft and didn't account for miles gained toward the target during climb.



Ok, from the take-off, climb and landing chart. 
at 7500lbs, 35.3 gallons to get 25,000ft this includes warm up and take according to fine print at the bottom of that section of the chart. More on this later. 

20 minute combat allowance, computed by me of 29.5 gallons using the percentage difference in fuel consumption between max continuous at 15,000ft and military power at 15,000. 
take the percentage difference an multiply times 62 gph and then divide by 3 for 20 minutes. about 29 gallons 

the 30 minute reserve. 16 gallons according to column V of the chart at sea level. 

total is 81 gallons rounding down.

congratulations you have* 39 gallons* of fuel for cruising. 
According to column I of the chart that should be good for 220 miles at a speed of 350mph which is higher than needed. Radius 110 miles. 
Running at 310-315mph could extend range somewhat and take the engine out of the max continuous power setting which is warned against in Note (A) in the instructions. 
"Avoid continuous cruising in column I except in emergency" 

a couple of points,
1, I used an online calculator to go from IAS to true airspeed so result is a bit generic.
2, the speed numbers in Column I may be a bit optimistic? 
AS a check I converted the IAS at 15,000ft to true MPH and got 375.7mph. Plane test at Aircraft Performance has top speed at 16,100ft as 389.5mph using 3000rpm and 46.7in of MAP. 
Engine running 400rpm slower and lower manifold pressure only goes 14mph slower? 

BTW (from 1st paragraph) there may be one or more errors in the Take-off, climb and landing chart. At 8000lbs doing a ferry climb to 25,000ft the P-39N was supposed to use 31.2 gallons of fuel.
unfortunately it used 38.1 getting to 15,000ft and 34.6 gallons getting to 10,000ft according to the chart. Is this the secret to the P-39N's performance? It made fuel as it climbed? 
Also the times to altitude vs fuel burn seem a little off. As in it takes 5.8 minutes to go from 10,000ft to 15,000ft during the Ferry climb (2300rpm/31in MAP) but the plane only uses 3.5 gallons of fuel?

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## GregP (May 25, 2021)

Good job SR6.

I surely hope so, but I'm betting it won't be enough ...

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## FLYBOYJ (May 26, 2021)

Appreciate you looking at this - just a few questions



Shortround6 said:


> Ok, from the take-off, climb and landing chart.
> at 7500lbs, 35.3 gallons to get 25,000ft this includes warm up and take according to fine print at the bottom of that section of the chart. More on this later.
> 
> *20 minute combat allowance, computed by me of 29.5 gallons using the percentage difference in fuel consumption between max continuous at 15,000ft and military power at 15,000.
> take the percentage difference an multiply times 62 gph and then divide by 3 for 20 minutes. about 29 gallons*




I computed a 10 minute combat at max power (147 GPH) in my calculations assuming a quick powerful encounter, this was a subjective choice. Why are you splitting the "combat allowance" between max continuous and military power? Is this subjective or do you have a reason for this?



Shortround6 said:


> According to column I of the chart that should be good for 220 miles at a speed of 350mph which is higher than needed. Radius 110 miles.
> Running at 310-315mph could extend range somewhat and take the engine out of the max continuous power setting which is warned against in Note (A) in the instructions.
> "Avoid continuous cruising in column I except in emergency"


If this is being used for a cruise, unless you're time pressed, why not use Column V for Maximum range? I mean, isn't the purpose of this exercise is to squeeze every mile we can out of this dog?


Shortround6 said:


> a couple of points,
> 1*, I used an online calculator to go from IAS to true airspeed so result is a bit generic.*
> 2, the speed numbers in Column I may be a bit optimistic?
> AS a check I converted the IAS at 15,000ft to true MPH and got 375.7mph. Plane test at Aircraft Performance has top speed at 16,100ft as 389.5mph using 3000rpm and 46.7in of MAP.
> Engine running 400rpm slower and lower manifold pressure only goes 14mph slower?



Using a IAS to TAS calculator - how are you calculating this without OAT? Are you using a standard lapse rate in the calculator or a 0.02 estimation correction? If we are doing a model with no real world conditions (actual temp, atmospheric pressure winds) you can almost plug in any number you want.


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## Greg Boeser (May 26, 2021)

*Stop interjecting real world considerations into our totally theoretical calculations!* 
By the way, since we climbed to 25000' and the P-39 has a combat ceiling of 35000', we should get up there and catch the jet stream for an even better boost in range. Assuming that we are attacking in the most favorable conditions. Then after combat we duck back down and use a nice shallow dive, power off, to get back home.

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## P-39 Expert (May 26, 2021)

Shortround6 said:


> Ok, from the take-off, climb and landing chart.
> at 7500lbs, 35.3 gallons to get 25,000ft this includes warm up and take according to fine print at the bottom of that section of the chart. More on this later. *Again, figures from the take off, climb and landing chart have nothing to do with range. The takeoff allowance for range calculation is 20gallons for this particular plane in clean condition.*
> 
> 20 minute combat allowance, computed by me of 29.5 gallons using the percentage difference in fuel consumption between max continuous at 15,000ft and military power at 15,000.
> ...



Please expand above.


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## P-39 Expert (May 26, 2021)

Greg Boeser said:


> Nobody climbed directly toward the target when taking off. And just what the hell are you doing flying off with out the rest of your formation? Standard practice was to take off, circle the field while the rest of your flight formed up, then when all elements of the formation were in place, climb to cruise altitude. If you are escorting bombers you need to throttle back to avoid separating from your charges.


See my post #1546. first paragraph.


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## P-39 Expert (May 26, 2021)

Greg Boeser said:


> *Stop interjecting real world considerations into our totally theoretical calculations!*
> By the way, since we climbed to 25000' and the P-39 has a combat ceiling of 35000', we should get up there and catch the jet stream for an even better boost in range. Assuming that we are attacking in the most favorable conditions. Then after combat we duck back down and use a nice shallow dive, power off, to get back home.


Actually for the P-39N service ceiling was 38500ft, combat ceiling was 31000ft (climb at 1000fpm) and the Flight Operation Instruction Chart (range chart) says it will cruise at 30000ft.


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## pbehn (May 26, 2021)

Greg Boeser said:


> *Stop interjecting real world considerations into our totally theoretical calculations!*
> .


Like clouds? With heavy cloud a formation has to head into it well separated but on the same rate of climb and direction. This is to hopefully get through the cloud without collisions and in roughly the same place. I have read of collisions and pilots emerging above but not able to find each other. Shouting "I am over here" doesnt help, I am told.

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## rochie (May 26, 2021)

this thread is like mud wrestling with a pig.

eventually you realise the pig actually likes it !

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## wuzak (May 26, 2021)

P-39 Expert said:


> *Again, figures from the take off, climb and landing chart have nothing to do with range. The takeoff allowance for range calculation is 20gallons for this particular plane in clean condition.*



So, 20 Gallons to get to the cruising altitude, whether that is 5,000ft or 30,000ft?


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## Shortround6 (May 26, 2021)

*Again, figures from the take off, climb and landing chart have nothing to do with range. The takeoff allowance for range calculation is 20gallons for this particular plane in clean condition.*

_And that 20 gallons gets you to 5,000ft. If you want to fly higher to do not pick and attitude and the range connected with that altitude and magically (pixie dust?) get it. You want to fly at 10,000ft or 20,000ft you have to expend the energy needed to lift the plane's weight to that altitude. _

_*That's for combat at 15000ft. Are we cruising at 25000ft? Then combat should be at 25000ft. I figure combat GPH in column I by converting normal power to combat power by dividing the GPH by 2600 (max cont. RPM) and multiplying that by 3000 (combat RPM). At 25000ft GPH is 62 divided by 2600 X 3000 = 72GPH. 20 minutes at 72GPH = 24gallons.* _

_Problem is you are being too simplistic. change your engine rpm by 400rpm and the impeller in the supercharger changes by 3840rpm. Power required by the supercharger changes with the square of the speed. Likewise the boost the supercharger supplies changes with the square of the speed of the impeller. Chart says at 15,000ft the plane cruises at 103gph but the Military power is 147gph at 14,600ft (close enough) so military power uses 43.7% more fuel per hour or minute. This may not be accurate for a number of reasons but it is a lot closer than simply comparing the rpm. This can be seen to be happening by comparing column II to column I. both columns use the same rpm but use different manifold pressures. _

So we are back to 39 gallons for cruise range/radius.

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## Shortround6 (May 26, 2021)

FLYBOYJ said:


> I computed a 10 minute combat at max power (147 GPH) in my calculations assuming a quick powerful encounter, this was a subjective choice. Why are you splitting the "combat allowance" between max continuous and military power? Is this subjective or do you have a reason for this?



I am using the 20 minute combat allowance because that is what the Air Force in their charts for operational radius. I am not "splitting the difference" but trying to estimate the military power fuel burn at 25,000ft. 




> If this is being used for a cruise, unless you're time pressed, why not use Column V for Maximum range? I mean, isn't the purpose of this exercise is to squeeze every mile we can out of this dog?



Well our "expert" claimed the P-39 could be used to escort 8th Air Force bombers if only the high command hand not been so stupid. So it has to fly as high and as fast as the planes that were used to escort the bombers. Not putz around at 5,000ft 250 IAS at 5-6,000 providing target practice for AA gunners and low time Luftwaffe pilots. (British learned about low speed low altitude cruise in 1941) 




> Using a IAS to TAS calculator - how are you calculating this without OAT? Are you using a standard lapse rate in the calculator or a 0.02 estimation correction? If we are doing a model with no real world conditions (actual temp, atmospheric pressure winds) you can almost plug in any number you want.



Well, it is quick and easy 
the calculator uses the 0.02 estimate correction and as long as we are all aware of it we are close to being on the same page. 

The Air Corp jumped around a bit using true airspeed on some charts and IAS on other and not only mixed them up on the same chart but sometimes mislabeled them. 
The P-39Q flight manual being a case in point. Column I being labeled IAS but unless you believe the P-39Q could cruise at 330mph IAS at 25,000ft (495mph true )
something is way off and that is the easiest explanation. 

I use True Airspeed Calculator

simply because it is quick and easy, making no claims for accuracy for actual navigation purposes. Somebody else uses something different and the answer is off by 10-15mph out of 300 mph I am not going to argue.

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## Peter Gunn (May 26, 2021)

P-39 Expert said:


> Please allow me to clarify the Flight Operation Instruction Chart (range chart) for you.



The best way to sway an argument/debate with a real life pilot when you're not a real life pilot.



P-39 Expert said:


> The range chart is all the pilot needed to plan a mission. To compute range for a mission the allowance for warm-up, takeoff and climb to 5000ft (20gal for P-39N) was deducted from total fuel then that net fuel was divided by gallons per hour and multiplied by TAS (not IAS). That's how all the ranges in each column are computed. For example look at column III at 15000ft. 70net gal divided by 67GPH X 300 TAS (242 IAS) = 313miles. The graph shows 300miles but the actual miles were rounded down a little as a safety factor. Same for all the columns at all altitudes (except column I). Gallons divided by GPH X TAS = range. The Fuel from Sea Level on the Take off, Climb and Landing Chart was not used since it already included the 20gal allowance for Warmup, Takeoff and Climb to 5000ft and didn't account for miles gained toward the target during climb.d



"A" pilot, what about a squadron?



P-39 Expert said:


> To get combat range simply deduct the 20min combat reserve and 20 minute reserve for landing in addition to the 20gal reserve for takeoff. To get combat radius take half of the combat range. The reserves could vary if you wanted a longer combat or landing reserve.



Bifff - you taking notes here?



P-39 Expert said:


> The range figures for column I (max cont. power/normal power) vary widely depending on what altitude is used. Right above the range figures in column I it says "At 12000ft Only" meaning the range figure is accurate only at 12000ft. This is because the gallons per hour (GPH) vary from about 100GPH up to 15000ft and then reduce steadily to only 62GPH at 25000ft. So range at 25000ft would be 70gallons divided by 62GPH X 350mph TAS (233mph IAS at 25000ft) = 395mi instead of the 210mi shown on the chart. This is the result of lower GPH coupled with higher TAS at 25000ft than at 12000ft. The other columns II through V show what throttle/propeller/altitude settings will result in the range for that column. Column I fixes the power setting at max. continuous (2600rpm) so the GPH and TAS will vary significantly as altitudes increase. Naturally I prefer to use 120gallons internal instead of the 88.



So you don't use any fuel going from 12,000ft to 25,000ft? And the chart is apparently wrong showing a range of 210 miles whereas you come up with 395 miles?



P-39 Expert said:


> As to whether the P-39N will fight at 25000ft, the cruising speed in column I was 350mph (233 IAS), the top speed was 370mph and the rate of climb (clean) was 1950fpm per the Wright Field performance tests. Climb at 25000ft was better than any P-40, P-38F/G, P-47, P-51A, F4U, F6F, Zero, Ki-43 or Typhoon in 1943. About the same as a Me109G. But not nearly as good as the Spitfire IX. P-39N was certainly competitive in 1943.



So you contend that in 1943, the P-39 was not only capable of long range high altitude escort deep into Germany, but for taking on German interceptors on more than an equal footing? The movie Fantasia called, they want their dancing hippos back.



P-39 Expert said:


> There is a IAS-TAS conversion chart in the P-39Q manual that curiously is not in this P-39N manual.



Per Joe in his post above _"how are you calculating this without OAT? Are you using a standard lapse rate in the calculator or a 0.02 estimation correction? If we are doing a model with no real world conditions (actual temp, atmospheric pressure winds) you can almost plug in any number you want."_

Also you mentioned that since we're cruising at 25,000 ft, combat should be at same. Uh, have you ever read encounter reports? Mustang Encounter Reports

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## DerAdlerIstGelandet (May 26, 2021)

I would love to close this thread, but then another thread would get hijacked.

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## FLYBOYJ (May 26, 2021)

P-39 Expert said:


> Again, figures from the take off, climb and landing chart have nothing to do with range. The takeoff allowance for range calculation is 20gallons for this particular plane in clean condition.


 And no matter how you slice it you're still burning a substantial amount of fuel if you take off and go straight to altitude, and please don't cloud the issue with some operational procedure or event.


P-39 Expert said:


> That's for combat at 15000ft. Are we cruising at 25000ft? Then combat should be at 25000ft. I figure combat GPH in column I by converting normal power to combat power by dividing the GPH by 2600 (max cont. RPM) and multiplying that by 3000 (combat RPM). At 25000ft GPH is 62 divided by 2600 X 3000 = 72GPH. 20 minutes at 72GPH = 24gallons.


OK - so doing it this way save you about 3-5 gallons from mine and SR calculations, I'll give you that, but during this simulated combat scenario you burnt up 1/4 of your fuel. Combine that with the fuel that got you to 25,000 feet and you better have a short trip home!


P-39 Expert said:


> *120 less 60 = 60gallons for cruising.*


This is 100% wrong - the P-39N flight manual CLEARLY shows the internal fuel at 87 Gallons in the weight and balance report. Here....






So maybe this stealth 120 gallon fuel capacity you keep mentioning is "the fuel being made" when you climb as SR pointed out?


P-39 Expert said:


> Again, you don't use any figures from the Takeoff, Climb and Landing Chart in computing range*.*


OMG, SMH - so the fuel burnt during that time just "goes away"? You magically put that fuel back in the tank and press on? *CLIMB GRADIENT?!? * That's the only thing I added in my calculations - ever heard of it???



P-39 Expert said:


> Actually for the P-39N service ceiling was 38500ft, combat ceiling was 31000ft (climb at 1000fpm) and the Flight Operation Instruction Chart (range chart) says it will cruise at 30000ft.


 And can it effectively fight at these altitudes? NO. If that was possible General Kenny would have kept the P-39 in the SWP and never messed with the P-38!

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## FLYBOYJ (May 26, 2021)

Shortround6 said:


> Well, it is quick and easy
> the calculator uses the 0.02 estimate correction and as long as we are all aware of it we are close to being on the same page.
> 
> The Air Corp jumped around a bit using true airspeed on some charts and IAS on other and not only mixed them up on the same chart but sometimes mislabeled them.
> ...


Agree 100% and that's why for simplicity I used IAS - our friend doesn't seem to grasp that temp and air pressure are major factors in computing IAS to TAS


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## Juha3 (May 26, 2021)

Peter Gunn said:


> Wait... a P-39 _fighting_ at 25,000 feet...
> 
> ...
> 
> ...



In fact the last kill of the Leningrad area PVO (air defence) was made by a pair of Airacobras from 103 GIAP with a pair of La-5s from 11 GIAP intercepting a Ju 88S at 9000m (29500 ft) on 8 March 1945, the German crew was taken prisoners.

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## FLYBOYJ (May 26, 2021)

Juha3 said:


> In fact the last kill of the Leningrad area PVO (air defence) was made by a pair of Airacobras from 103 GIAP with a pair of La-5s from 11 GIAP intercepting a Ju 88S at 9000m (29500 ft) on 8 March 1945, the German crew was taken prisoners.



Juha - do you know how many claims P-39 were recorded by the VVS? I'm trying to find data for Soviet P-39 claims vs Luftwaffe claims of P-39s


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## GrauGeist (May 26, 2021)

DerAdlerIstGelandet said:


> I would love to close this thread, but then another thread would get hijacked.


This thread is sort of like a porch light with little P-39s buzzing around it...

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## P-39 Expert (May 26, 2021)

Shortround6 said:


> *Again, figures from the take off, climb and landing chart have nothing to do with range. The takeoff allowance for range calculation is 20gallons for this particular plane in clean condition.*
> 
> _And that 20 gallons gets you to 5,000ft. If you want to fly higher to do not pick and attitude and the range connected with that altitude and magically (pixie dust?) get it. You want to fly at 10,000ft or 20,000ft you have to expend the energy needed to lift the plane's weight to that altitude. _
> 
> ...


The 20 gallons gets you to 5000ft, then climbing to 25000ft *toward the target* nets additional range. Let's say it takes 15 more minutes to 25000ft and average climb speed is 220mph (170mph IAS) then the climb toward target adds 55miles to range. I don't think the pilot climbed to 25000ft over the base and then vectored toward the target, he vectored toward the target asap after takeoff. All that is figured into the chart.

Figuring combat GPH is an estimate since that figure is not provided in the chart. I believe my simplistic method of converting max cruise RPM (2600) to combat RPM (3000) is close enough at that altitude. Using your example the 62GPH at 25000ft converted to combat power would be 89GPH. I wish it were so but I just don't think it's possible. I'll stick with my figure, we agree to disagree.


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## Glider (May 26, 2021)

wuzak said:


> So, 20 Gallons to get to the cruising altitude, whether that is 5,000ft or 30,000ft?



That's the bit I like. It takes the P39N 1.45 mins to 5,000ft approx. 3.15 mins to 12,000ft and 8.4 mins to 25,000ft. According to P39 this extra 5+ minutes climb and the fuel you use in that time to get to 25,000ft quote '*have nothing to do with range'*

I know that I am much happier in a Glider where this isn't concern, but I wouldn't trust my life in the hands of someone with this belief.

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## GregP (May 26, 2021)

Hi SR6,

I was hoping, but I suspected your very complete post earlier would not be enough. So, I fall back on one particular definition of insanity as "doing the same thing over and over while for a different result each time."

Perhaps some distraction? 
1) What do they pack styrofoam in when they ship it?
2) Statistics will show that 1 out of every 4 babies born in the world is Chinese. So, if you have 3 kids and your wife is pregnant, do you ever worry about that?
3) If you're not supposed to drink and drive, why do they have drive-through liquor stores?
4) I bought some dehydrated water, but I didn't know what to add ...

ba da boom ...

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## pbehn (May 26, 2021)

P-39 Expert said:


> Figuring combat GPH is an estimate since that figure is not provided in the chart. I believe my simplistic method of converting max cruise RPM (2600) to combat RPM (3000) is close enough at that altitude. Using your example the 62GPH at 25000ft converted to combat power would be 89GPH. I wish it were so but I just don't think it's possible. I'll stick with my figure, we agree to disagree.


Dear me, when will this end? Figuring out this stuff isnt an estimate. Read this. AC Eng Perf Analysis at R-R Which is about the RR XX Merlin in the main but also includes discussion of the Allison V 1710. The people at the time knew the far end of a fart about this "stuff". If you understand it all you are a better man than I, I just understand the principles. I KNOW the people at the time knew the actual and theoretical consumption of their engines at all engine speeds, altitudes and boost setting with a lot of other variables thrown in too.

Edit, from what I know the consumption related to the swept volume/2, the RPM, the boost pressure, and the mixture setting. The difference between max economy and max short term power consumption is typically 1:3. so 50gph and 150gph on a Merlin (in the roundest of round numbers) This is why a Spitfire could be running low on fuel after a short time in combat at 30,000ft.

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## Glider (May 26, 2021)

P-39 Expert said:


> I don't think the pilot climbed to 25000ft over the base and then vectored toward the target, he vectored toward the target asap after takeoff.


So you plan sending your fighters into the attack one at a time? Don't you think forming up is a good idea?


> I believe my simplistic method of converting max cruise RPM (2600) to combat RPM (3000) is close enough at that altitude.


Simplistic is one word that fit's, that I grant you.

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## buffnut453 (May 26, 2021)

DerAdlerIstGelandet said:


> I would love to close this thread, but then another thread would get hijacked.



Could always ban him for the sheer monotony generated?

Yes, I know...that's neither fair nor nice. I'm beginning to realize that he simply doesn't know what he doesn't know, hence he thinks everything he does know is correct (if you get my drift).

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## FLYBOYJ (May 26, 2021)

So I guess there’s no such thing as a climb or descent gradient? I guess my C172 has just turned into a helicopter! Oh but wait, it doesn’t matter because I have reserve fuel that’s specifically for take off and landing! 😉


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## buffnut453 (May 26, 2021)

Just had to post this...in case there are any Blackadder fans out there:



It reminded me of someone....

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## Glider (May 26, 2021)

It goes to show that if someone has a belief you cannot discuss things with them, because that have a belief. That belief encourages them to make wild assumptions and statements that support that belief because they need something to support the belief. To them it's logical and simple. How many times in the threads have the changes to armour, COG, installing new engines been described as 'simple' and 'obvious' and any evidence to the contrary more, or less ignored.

The evidence is irrelevant as they have a belief. When the evidence is against them, they often change the subject and ignore the unanswered questions. Partly because they know that they cannot supply the answers, but to recognise that would dent the belief and that cannot be allowed to happen.

You will notice that at the start of all this there was a recognition from P39 that the aircraft was better at low/medium altitude than higher up, which is true, it is better lower down. The problem was that he believed that it was supreme at low / Medium altitude which it clearly isn't. Now that has been proved beyond any shadow of doubt, he is now trying to pretend that it was better at 25,000ft, which a) it clearly isn't and b) Is contrary to his initial premise that it was better at lower altitude.

The belief that the P39N was some kind of wonder weapon ignores the fact that was little more than a twice around the airfield before it runs out of fuel fighter, ( a little harsh I know but you get the picture). The fact that a Typhoon could lug 2,000lb bombs further that the P39N can go clean sort of proves the point. I would expect the P51 to do something similar and the P40 probably has a better payload range. In fact the P39N doesn't really have much of a payload.

Why was the P39Q pretty much the last production version of the P39 if the P39N was so good?. I don't actually know the detailed reasons but we can assume it was because it was an improvement including the increase in fuel. The users were happy to accept the lower performance for those advantages, which tells me that there was something wrong with the P39N.

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## Dimlee (May 26, 2021)

pbehn said:


> I read years ago in a link I can no longer find that RAF 601 squadron had a Russian aviation expert attached to them when they were using the P-39. So when the P-39 arrived in Russia they had a good idea of what to do to make it a success. (Maybe
> 
> Dimlee
> can help with this). Did Bell have their own test pilots or any real feedback from pilots in the field? I just cant understand why this CoG issue went on throughout the war, with Bell designing a replacement for the P-39 and designing in the same ffing problem.



No, I never heard about a Soviet expert in RAF 601. Interesting story, if it's true.

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## buffnut453 (May 26, 2021)

Glider said:


> It goes to show that if someone has a belief you cannot discuss things with them, because that have a belief. That belief encourages them to make wild assumptions and statements that support that belief because they need something to support the belief. To them it's logical and simple. How many times in the threads have the changes to armour, COG, installing new engines been described as 'simple' and 'obvious' and any evidence to the contrary more, or less ignored.
> 
> The evidence is irrelevant as they have a belief. When the evidence is against them, they often change the subject and ignore the unanswered questions. Partly because they know that they cannot supply the answers, but to recognise that would dent the belief and that cannot be allowed to happen.
> 
> You will notice that at the start of all this there was a recognition from P39 that the aircraft was better at low/medium altitude than higher up, which is true, it is better lower down. The problem was that he believed that it was supreme at low / Medium altitude which it clearly isn't. Now that has been proved beyond any shadow of doubt, he is now trying to pretend that it was better at 25,000ft, which a) it clearly isn't and b) Is contrary to his initial premise that it was better at lower altitude.



DENY EVERYTHING, BALDRICK!!!


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## Glider (May 26, 2021)

Dimlee said:


> No, I never heard about a Soviet expert in RAF 601. Interesting story, if it's true.


I doubt that this is true, it would have been published if its true. Also if the first P39's the Russians had were the hand me downs from the UK ones which we rejected. How could there be a Russian expert?


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## FLYBOYJ (May 26, 2021)

Glider said:


> It goes to show that if someone has a belief you cannot discuss things with them, because that have a belief. That belief encourages them to make wild assumptions and statements that support that belief because they need something to support the belief. To them it's logical and simple. How many times in the threads have the changes to armour, COG, installing new engines been described as 'simple' and 'obvious' and any evidence to the contrary more, or less ignored.
> 
> The evidence is irrelevant as they have a belief. When the evidence is against them, they often change the subject and ignore the unanswered questions. Partly because they know that they cannot supply the answers, but to recognise that would dent the belief and that cannot be allowed to happen.
> 
> ...


Perfect! And lastly, why did General George Kenny, 5th AF do away with all of his P 39’s from front line units in favor of the P 38? Why is it that some of the very talented pilots of the 80th Fighter Group struggled to attain any significant kills with the P-39 but when P 38 operations began in late 1942, the kills skyrocketed?

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## pbehn (May 26, 2021)

Glider said:


> I doubt that this is true, it would have been published if its true. Also if the first P39's the Russians had were the hand me downs from the UK ones which we rejected. How could there be a Russian expert?


I read it ages ago on t'internet but cant find it now. Churchill offered help to the Soviet Union almost immediately after Germany invaded. There was a long time passed between Germany invading Russia and P-39s being put on ships. The article was mainly concerned with why the VVS enjoyed much better service with it than other forces. Mainly it was about using it to do things it could do, not things it couldnt, and being as well prepared for the Eastern Front as possible, which started before the planes were shipped.

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## GrauGeist (May 26, 2021)

FLYBOYJ said:


> Perfect! And lastly, why did General George Kenny, 5th AF do away with all of his P 39’s from front line units in favor of the P 38? Why is it that some of the very talented pilots of the 80th Fighter Group struggled to attain any significant kills with the P-39 but when P 38 operations began in late 1942, the kills skyrocketed?


It's obvious that the Japanese weren't afraid of the P-38.
But when they heard the fearsome P-39 was in the area, they ran for shelter.

This is clearly the reason behind the disparity in claims between the two types...

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## FLYBOYJ (May 26, 2021)

GrauGeist said:


> It's obvious that the Japanese weren't afraid of the P-38.
> But when they heard the fearsome P-39 was in the area, they ran for shelter.
> 
> This is clearly the reason behind the disparity in claims between the two types...
> ...


I believe that was straight out of the flight manual!


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## pbehn (May 26, 2021)

Dimlee
Not the article I read, but this does state Soviet pilots were training with 601 squadron, not unreasonable to think they had a senior person in charge of it all.

*Airacobras in the Soviet Union *
Quote. Soviet pilots had first seen the Airacobra in Great Britain, when a group of pilots was sent to No. 601 Squadron at RAF Duxford for training. The British had found the Airacobra unsuitable for their own use and were more than happy to turn over their Airacobras to the Soviets, and some 212 of the 675 Airacobra Is ordered by the RAF were diverted to the USSR. The Airacobras first entered service with the Soviet Air Force in May of 1942.

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## Glider (May 26, 2021)

pbehn said:


> Dimlee
> Not the article I read, but this does state Soviet pilots were training with 601 squadron, not unreasonable to think they had a senior person in charge of it all.
> 
> *Airacobras in the Soviet Union *
> Quote. Soviet pilots had first seen the Airacobra in Great Britain, when a group of pilots was sent to No. 601 Squadron at RAF Duxford for training. The British had found the Airacobra unsuitable for their own use and were more than happy to turn over their Airacobras to the Soviets, and some 212 of the 675 Airacobra Is ordered by the RAF were diverted to the USSR. The Airacobras first entered service with the Soviet Air Force in May of 1942.



Interesting information and something I hadn't heard before. I admit my first thought was the most senior person would probably be the NKVD Commissar, but that's just me.

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## Shortround6 (May 26, 2021)

Alternative method for figuring fuel burn in combat at 25,000ft for the P-39.
Take power at 14,600ft (1150hp) divide by fuel burn (147 gallons an hour) for 7.82hp per gallon, rounded down.

Find HP in performance reports At WW II Aircraft Performance. 
770hp at 25,000ft in high speed level flight. Divide by 7.82 and you get 98.46 gallons an hour or 32.8 gallons for 20 minutes. 
Not as high as my early estimate but higher than 24 gallons for combat for 20 minutes.

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## pbehn (May 26, 2021)

Glider said:


> Interesting information and something I hadn't heard before. I admit my first thought was the most senior person would probably be the NKVD Commissar, but that's just me.


The introduction and operation of Hurricanes is better documented. There was an agreement to provide the planes and a nucleus of pilots and staff to get things running. Just from looking at 601 squadron history maybe the same was done with the P-39 but in UK. 601 only did two operations on 9-11 October 1941, it was taken off operations in December but 601 didnt switch to Spitfires until March.


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## glennasher (May 26, 2021)

Shortround6 said:


> Alternative method for figuring fuel burn in combat at 25,000ft for the P-39.
> Take power at 14,600ft (1150hp) divide by fuel burn (147 gallons an hour) for 7.82hp per gallon, rounded down.
> 
> Find HP in performance reports At WW II Aircraft Performance.
> ...




Could the Bell even fight at 25,000 feet?, it seems like it wouldn't be worth the trouble to get to that altitude, and have the poor performance as indicated.


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## pbehn (May 26, 2021)

glennasher said:


> Could the Bell even fight at 25,000 feet?, it seems like it wouldn't be worth the trouble to get to that altitude, and have the poor performance as indicated.


The Airacobra I was powered by an Allison V-1710-E4 twelve-cylinder V in-line engine rated at 1150 hp for takeoff. Weights were 5462 pounds empty and 7845 pounds normal gross. Maximum speeds were 326 mph at 6000 feet, 343 mph at 10,000 feet, 355 mph at 13, 000 feet, 341 mph at 20,000 feet. Initial climb rate was 2040 feet per minute. With an internal fuel capacity of 100 Imp gal the Airacobra had an endurance of 1 hour 20 minutes at maximum continuous cruising speed at 6000 feet, 1 hour 5 minutes at 12,000 feet, and 1 hour 35 minutes at 20,000 feet. The true airspeeds at these altitudes were 287 mph, 327 mph, and 308 mph, respectively. Under most economical cruise conditions, the endurance increased to 3 hours 20 minutes, the relevant speeds being 183 mph at 6000 feet, 217 mph at 12,000 feet, and 215 mph at 20,000 feet. Under maximum continuous climb conditions, it took 15 minutes to reach 20,000 feet. The operational ceiling was considered to be about 24,000 feet, although there was a marked decrease in performance above 20,000 feet. At the Airacobra's rated altitude of 13,000 feet, it was 18 mph faster than the Spitfire VB. However, the speed fell off rapidly above that height, and the two planes were almost exactly matched at 15,000 feet. At 20,000 feet, the Spitfire VB was 35 mph faster and at 24,000 feet it was 55 mph faster. The ground run of the Airacobra during takeoff was 2250 feet, as compared with 1470 feet for the Hurricane II and 1590 feet for the Spitfire V.


Airacobra I for RAF, P-400

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## Juha3 (May 26, 2021)

FLYBOYJ said:


> Juha - do you know how many claims P-39 were recorded by the VVS? I'm trying to find data for Soviet P-39 claims vs Luftwaffe claims of P-39s



Hello Flyboyj
sorry, no. All i can say is that the pilots of 9 GIAD, the Fighter Division whose pilots were credited highest number of kills of the P-39 equipped divisions and also probably of the all VVS fighter divisions, scored 1147 aerial kills. This according to Mellinger. But IIRC the highest scoring P-39 regiment was only the 3rd in regimental ranking.

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## FLYBOYJ (May 26, 2021)

Juha3 said:


> Hello Flyboyj
> sorry, no. All i can say is that the pilots of 9 GIAD, the Fighter Division whose pilots were credited highest number of kills of the P-39 equipped divisions and also probably of the all VVS fighter divisions, scored 1147 aerial kills. This according to Mellinger. But IIRC the highest scoring P-39 regiment was only the 3rd in regimental ranking.


Thank you!


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## Juha3 (May 26, 2021)

glennasher said:


> Could the Bell even fight at 25,000 feet?, it seems like it wouldn't be worth the trouble to get to that altitude, and have the poor performance as indicated.



At lest Ns and Qs could, see the message #1,569. One reason why some of them were allocated to PVO units, as air defense interceptors.


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## Juha3 (May 26, 2021)

A bit OT but the top three VVS fighter regiments, 402 IAP 810 kills, notice, in spite of its achievements it did not get the Guard title. At the beginning of the Great Patriotic War equipped with MiG-3s, then with different Yaks.
5 GIAP (ex-129 IAP) 735 kills, I-16, MiG-3, LaGG-3, La-5 and at the very end of the war La-7
16 GIAP (ex-55 IAP), 697 kills, notice, not all under 9 GIAD with P-39s but was equipped before that period with I-153s/I-16s/MiG-3s at the beginning of the war (was converting from older fighters to MiG-3s), then Yak-1s before converting to P-39s at the beginning of 1943.

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## Shortround6 (May 26, 2021)

Our Expert is claiming a number of things. 
One is that the P-39N seems to have been the answer to most of the allies fighter requirements. 
Early P-39s, Aircobra I/P-400s used 8.80 supercharger gears and had about 1150hp at 12,000ft.

Since the later P-39N had 9.60 supercharger gears and was supposed to make 1125hp at 15,500ft (why the flight operation chart for the P-39N says 14,600ft I don't know) this seems to transform the P-39 from a fighter that struggled at 20,000ft and above to one that could take on or perform nearly as well as any fighter in the world in 1943 at well above 20,000ft. 

Sometimes I apply the "smell" test. 
P-39 with the uprated engine had about 770hp at 25,000ft including RAM for a plane that weighed about 7000lbs or bit more (depending on fuel burn off) 
P-51B had an engine that gave 1300hp at 26,400ft no ram and 1300hp at 32,000ft with ram at military rating for a plane that went just under 9000lbs with 1/3 of it's fuel burned off. 
P-51B using WER had 1410hp at 29,300ft with ram. 

P-51B had 180 gallons internal and was rated at a 150 mile combat radius.
Our Expert is claiming that the P-39 with 2/3rds the fuel could do as well???

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## FLYBOYJ (May 26, 2021)

Shortround6 said:


> Our Expert is claiming a number of things.
> One is that the P-39N seems to have been the answer to most of the allies fighter requirements.
> Early P-39s, Aircobra I/P-400s used 8.80 supercharger gears and had about 1150hp at 12,000ft.
> 
> ...



I also think he is mixing and confusing information from the P-39N manual and the P-39Q manual. *Both manuals show internal fuel capacity of 87 gallons in the weight and balance charts. I see no reference of 120 gallons.*

He is correct about the IAS/ TAS conversion table only found in the P-39Q manual. With no instruction to convert in the earlier manuals, I think there was the source of some confusion (as you pointed out earlier).

Bottom line, I think with some of the numbers shown, the P-39 had a dismal high altitude intercept radius.


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## Thumpalumpacus (May 26, 2021)

P-39 Expert said:


> *Are we cruising at 25000ft? Then combat should be at 25000ft. *



That doesn't follow. What if the enemy is climbing up to you? Are you gonna wait 'til they get to your altitude before attacking? And if you don't get shoot-downs on the first diving pass, aren't you still flying and fighting at a lower level?

This is a _non sequitur_. Combat altitude and cruise altitude are not necessarily the same. Sloppy thinking, ten yards and loss of a down.

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## pbehn (May 26, 2021)

FLYBOYJ said:


> I also think he is mixing and confusing information from the P-39N manual and the P-39Q manual. *Both manuals show internal fuel capacity of 87 gallons in the weight and balance charts. I see no reference of 120 gallons.*
> 
> He is correct about the IAS/ TAS conversion table only found in the P-39Q manual. With no instruction to convert in the earlier manuals, I think there was the source of some confusion (as you pointed out earlier).
> 
> Bottom line, I think with some of the numbers shown, the P-39 had a dismal high altitude intercept radius.


I think they removed fuel cells from the wings and supplied them as kits. Quote "500 of P-39Ns were built, with all but the first 160 featuring elimination of three internal fuel cells to reduce weight. The P-39N could of course carry an external tank to compensate for the smaller internal fuel load, and service units that wanted the full internal fuel load back could install a field upgrade kit to restore the deleted fuel cells. "
From The Bell P-39 Airacobra & P-63 Kingcobra.


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## FLYBOYJ (May 26, 2021)

pbehn said:


> I think they removed fuel cells from the wings and supplied them as kits. Quote "500 of P-39Ns were built, with all but the first 160 featuring elimination of three internal fuel cells to reduce weight. The P-39N could of course carry an external tank to compensate for the smaller internal fuel load, and service units that wanted the full internal fuel load back could install a field upgrade kit to restore the deleted fuel cells. "
> From The Bell P-39 Airacobra & P-63 Kingcobra.



Good info, but it seems our friend played with the example that was going to give the greatest range. The external tank installation is indicated clearly in the W&B report

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## Thumpalumpacus (May 26, 2021)

Also -- this thread has longer legs than any -39 that ever flew.

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## ThomasP (May 27, 2021)

I'm so confused!! 

Which aircraft are we comparing now? The reason I ask is that the latest thread (now sub-thread) started with P-39 v P-40, then switched to the P-39 v F4U, then P-39 v ?, and now P-39 v P51.

Questions:

1. Is there really any question (in anyone's mind) that the P-39 (any variant) can be grossly outranged by the F4U-x, P-38x, P-51x? Except maybe on a Point Local intercept, where internal fuel and DTs would not be used for range (ie WUTO, ~max climb to intercept altitude (whatever is suitable for the aircraft), combat, return to Home base/nearby base and land on fumes if necessary)??

2. Is there any question that the main limitation to a P-39 long range mission is the internal fuel load (87 or 120 USgal)? Just as it is for any of the other aircraft (ie If the profile is internal for WUTO and initial climb, switch to DT for climb to operational altitude, DT for cruise outbound, drop DTs at/near point of contact, internal for combat, internal for cruise home, internal for some amount of reserve at/near home)??

3. Which variant of the P-39 are we using for the comparison? If I understand correctly, P-39 Expert is using a variant of the P-39N with either 87 or 120 USgal internal fuel (depending on mission profile), armed with 1x37mm or 20mm and 2x.50 cal, lightened and rebalanced through a change in armament, reduced armour, with a reposition/removal of some equipment. The idea being that the P-39 could have been significantly more capable in modified form. (I am leaving out the possibility of the engine change to the -93 model due to the current discussion being focused on the range and altitude issues of the standard variants.) It should not be difficult to specify the operational weights, and agree on ~speeds, ROC, fuel burn, etc.

Answers please.


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## GregP (May 27, 2021)

I view this thread as a cognitive dissonance with regard to motivational committance. 

It is similar to needing a good, long-range, high-altitude fighter, but only having a P-39 available. 

What is the point, especially when you can't even take time to join up with your flight because the range is too short to go around the pattern more than a couple of times without drop tanks. The airplane is in a state of virtual fuel emergency when it is gassed up, oiled up, and ready to start the engine. Heck, with P-39's range, you don't even need a relief tube!

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## Stig1207 (May 27, 2021)

> Lieutenant Colonel of the Guards Alexander I. Pokryshin, a Soviet ace with 59 kills to his credit, scored 48 of these in a P-39. He was awarded the Distinguished Flying Cross by President Roosevelt. There are eight other P-39 pilots with at least 20 kills. Among top Airacobra aces were Grigorii A Rechkalov (44 kills) , Nikolai D Gulayev (36 kills), Ivan I Babak, Aleksandr F Klubov, Andrei I Trud, and the brothers Boris B Glinka and Dmitrii B Glinka



Quoted from the link posted by PBehn to Joe Baugher's site.

I read an article in Flypast the other day, by Chris Goss iirc. It states that 204 Me 109 pilots scored more than 5 kills during the BoB, so they were credited with at least 1020 victories, but obviously more, so what would the average be 7 or 8? That would make 1400 to 1600 kills by Me 109 aces. 
RAF losses vary by source, but the highest figure I am aware of is 1500+ for Fighter Command, Bomber Command, and Coastal Command to *all causes.*

Aces scores are not a reliable yardstick for evaluating a particular fighter aircraft's combat performance. Perhaps the only thing that is overated with the P-39 is the Stalin Falcons' achievments with it.

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## pbehn (May 27, 2021)

FLYBOYJ said:


> Good info, but it seems our friend played with the example that was going to give the greatest range. The external tank installation is indicated clearly in the W&B report


The internal tanks were removed to reduce weight, so the best combination of range and high altitude performance is chosen for the benefit of the discussion. Use the external tank then drop it to go through the 25,000ft speed trap.

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## FLYBOYJ (May 27, 2021)

ThomasP said:


> I'm so confused!!
> 
> Which aircraft are we comparing now? The reason I ask is that the latest thread (now sub-thread) started with P-39 v P-40, then switched to the P-39 v F4U, then P-39 v ?, and now P-39 v P51.



"Take off at S/L and climb immediately to 20,000 feet. For the climb chart I'm going to "interpolate" a climb to 20,000' (because the climb chart goes from 15K to 25K). I'll then plug in a 15 minute cruise at 20K followed by "combat" at max power for 10 minutes. After that I'll show at 20,000' what fuel is left and the maximum range that is left."


ThomasP said:


> Questions:
> 
> 1. Is there really any question (in anyone's mind) that the P-39 (any variant) can be grossly outranged by the F4U-x, P-38x, P-51x? Except maybe on a Point Local intercept, where internal fuel and DTs would not be used for range (ie WUTO, ~max climb to intercept altitude (whatever is suitable for the aircraft), combat, return to Home base/nearby base and land on fumes if necessary)??


No doubt in my mind but to convince "experts" sometimes you have to painfully jump through hoops!


ThomasP said:


> 2. Is there any question that the main limitation to a P-39 long range mission is the internal fuel load (87 or 120 USgal)? Just as it is for any of the other aircraft (ie If the profile is internal for WUTO and initial climb, switch to DT for climb to operational altitude, DT for cruise outbound, drop DTs at/near point of contact, internal for combat, internal for cruise home, internal for some amount of reserve at/near home)??


No question in my mind!


ThomasP said:


> 3. Which variant of the P-39 are we using for the comparison? If I understand correctly, P-39 Expert is using a variant of the P-39N with either 87 or 120 USgal internal fuel (depending on mission profile), armed with 1x37mm or 20mm and 2x.50 cal, lightened and rebalanced through a change in armament, reduced armour, with a reposition/removal of some equipment. The idea being that the P-39 could have been significantly more capable in modified form. (I am leaving out the possibility of the engine change to the -93 model due to the current discussion being focused on the range and altitude issues of the standard variants.) It should not be difficult to specify the operational weights, and agree on ~speeds, ROC, fuel burn, etc.


 I used the example straight out of the posted P-39N flight manual with 87 gallons of fuel shown per the weight and balance report. It was pointed out that some aircraft had additional wing fuel tanks installed but those weren't used in my examples although our expert friend keep plugging in this and performance data from the P-39Q


ThomasP said:


> Answers please.


Hope this helps, any additional information you can add would be appreciated but probably not convincing to some!


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## P-39 Expert (May 27, 2021)

ThomasP said:


> I'm so confused!!
> 
> Which aircraft are we comparing now? The reason I ask is that the latest thread (now sub-thread) started with P-39 v P-40, then switched to the P-39 v F4U, then P-39 v ?, and now P-39 v P51.
> 
> ...


Please expand above.


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## P-39 Expert (May 27, 2021)

Shortround post #1564: Yes IAS was mislabeled in column I from P-39Q range chart. Correct that to TAS for cruising speeds at max. continuous. 330mph at 25000ft etc.
Shortround post #1590: Your combat reserve of 33gals vs mine of 24gals results in about a 50 mile difference. Not really significant. I'll stick with mine. 
Flyboy post #1567: Regarding fuel capacity, every production P-39 was built for 120gal internal fuel. AAF reduced fuel in some N and Q models, probably at the request of their primary user the Soviets. Kits were available to restore the full 120gal in the field. Any range discussion should use the normal 120gal. Also if the wing guns are removed there is room for more fuel, at least 30gal which would bring internal fuel up to 150gal, same as P-38F/G.
Flyboy post #1584: Again, 1942 P-39s were way too heavy (could have been lightened easily). Gen. Kenney had made up his mind about the P-39 and welcomed the P-38s. They came in about the time the vastly improved P-39N was available, end of 1942. And the AAF had already decided that (based on the 1942 P-39s) the war would be fought primarily with the P-38 and P-47 and the P-39 would be sent to Russia or used for training. Compared to the P-38F/G the P-39N climbed better and was faster under 20000ft. The Russians greatly benefitted from the lend lease P-39N/Q.


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## wuzak (May 27, 2021)

P-39 Expert said:


> P-39 was built for 120gal internal fuel. AAF reduced fuel in some N and Q models, probably at the request of their primary user the Soviets. Kits were available to restore the full 120gal in the field. Any range discussion should use the normal 120gal. Also if the wing guns are removed there is room for more fuel, at least 30gal which would bring internal fuel up to 150gal, same as P-38F/G.



The reduction from 120 USG to 87 USG was to reduce weight, like you've been banging on about for years now.

The N and Q were produced with 87 USG from the factory. Kits could be applied in the field to bring them up to 120USG, but how many were fitted and where?

Did the wings have the facilities for extra fuel tanks where the guns were mounted?


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## Peter Gunn (May 27, 2021)

So much to parse out, well...



P-39 Expert said:


> Shortround post #1564: Yes IAS was mislabeled in column I from P-39Q range chart. Correct that to TAS for cruising speeds at max. continuous. 330mph at 25000ft etc.



So, you're guessing at the TAS?



P-39 Expert said:


> Shortround post #1590: Your combat reserve of 33gals vs mine of 24gals results in about a 50 mile difference. Not really significant. I'll stick with mine.



Because it fits your narrative better?



P-39 Expert said:


> Flyboy post #1567: Regarding fuel capacity, every production P-39 was built for 120gal internal fuel. AAF reduced fuel in some N and Q models, probably at the request of their primary user the Soviets. Kits were available to restore the full 120gal in the field. Any range discussion should use the normal 120gal. Also if the wing guns are removed there is room for more fuel, at least 30gal which would bring internal fuel up to 150gal, same as P-38F/G.



Why should the range discussion be based on non-factual data? The plane did _not_ have 120 gallons of internal fuel, it also had wing guns instead of any extra fuel in that space and therefore it weighed what it weighed, there's no getting around those two FACTS.



P-39 Expert said:


> Flyboy post #1584: Again, 1942 P-39s were way too heavy (could have been lightened easily). *Gen. Kenney had made up his mind about the P-39 and welcomed the P-38s.*



Why do you suppose that was? You don't think a general in command of a numbered air force with responsibilities for the entire theater was unaware of any changes in hardware coming down the pipeline? I'd wage General Kenney was eminently aware of what aircraft with attending upgrades were in the works or on the horizon. Bottom line, the short ranged low altitude P-39 was not a viable asset for his command. Hell, he even had reservations about getting the P-47 because of range issues with the Thunderbolt. So when it came to the P-39 he correctly said _Nyet_.



P-39 Expert said:


> They came in about the time the vastly improved P-39N was available, end of 1942. And the AAF had already decided that (based on the 1942 P-39s) the war would be fought primarily with the P-38 and P-47 and the P-39 would be sent to Russia or used for training. Compared to the P-38F/G the P-39N climbed better and was faster under 20000ft. The Russians greatly benefitted from the lend lease P-39N/Q.



Why do you think the AAF ditched the Airacobra for the P-38 and the Thunderbolt? Perhaps AAF leadership was cognizant of realities you are not, like ETO ops required high altitude long range, and more importantly, high performance fighters, something the P-39 was incapable of achieving. You're saying your smarter than all the AAF gentlemen (and RAF) that tested, flew, examined etc. this plane and universally reached the conclusion that it was not suited for any combat EXCEPT short range low altitude ops? Also, the VVS fought a different war than did the AAF or the RAF, or are we forgetting this?

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## wuzak (May 27, 2021)

P-39 Expert said:


> *There were really only two P-39s, despite the variations that ran all the way up to Q. Main difference was their engines. 1942 P-39D/F/K/L had the -35 or -63 engines with critical altitude of 12000ft. They were limited to low and medium altitude (under 20000ft) because they were too heavy for their engine power. Unnecessary/redundant items (30cal wing guns, one piece or armor plate, IFF radio) could have been removed at front line bases to greatly improve climb/ceiling.*



Again, where are you planning to use this aircraft?

You are claiming that the P-39N compares to aircraft in the ETO. Do you want to use the P-39 in the ETO, then you need to keep the IFF.




P-39 Expert said:


> *1943 P-39N/Q had uprated -85 engines with higher S/C gear ratio and critical altitude of 15000ft. The N model had a 38,500ft ceiling and an excellent rate of climb at all altitudes at stated weight, nothing needed to be removed. Only real difference in the N and Q was wing guns. Remove the underwing podded 50calMGs from the Q and they were about the same as an N.*



The Spitfire V of 1941 had a critical altitude of 20,000ft (with ram). So a 15,000ft critical altitude in 1943 isn't very impressive.

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## Glider (May 27, 2021)

And we still have the questions
a) How much weight is involved adding the extra fuel plus its tanks and plumbing
b) If the N was so good why was it replaced with the Q which had less performance
c) You don't just rip out guns and add fuel
d) what is the performance of the N with the extra weight. My guess is that it will be very similar to the P39Q which was a very similar aircraft, which in turn knocks great holes in your claim for the P39N being such a wonder weapon

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## FLYBOYJ (May 27, 2021)

P-39 Expert said:


> Flyboy post #1567: Regarding fuel capacity, every production P-39 was built for 120gal internal fuel. AAF reduced fuel in some N and Q models, probably at the request of their primary user the Soviets. Kits were available to restore the full 120gal in the field. Any range discussion should use the normal 120gal. Also if the wing guns are removed there is room for more fuel, at least 30gal which would bring internal fuel up to 150gal, same as P-38F/G.


"Could have, would have, should have" once again you're cherry picking. I think you know as well as I the AAF units in the SWP (80th FG, 35th FS for example) that were using *P-39Ds* and *P-400s* did not operate with 120 gallon fuel tanks. Even with the extra fuel the P-38 F/G, let alone the J easily outranged the P-39. So please, stop trying to throw "what ifs" into what actually happened.



P-39 Expert said:


> Flyboy post #1584: Again, 1942 P-39s were way too heavy (could have been lightened easily).


Could have, would have, should have." 



P-39 Expert said:


> Gen. Kenney had made up his mind about the P-39 and welcomed the P-38s. They came in about the time the vastly improved P-39N was available, end of 1942. And the AAF had already decided that (based on the 1942 P-39s) the war would be fought primarily with the P-38 and P-47 and the P-39 would be sent to Russia or used for training. Compared to the P-38F/G the P-39N climbed better and was faster under 20000ft. The Russians greatly benefitted from the lend lease P-39N/Q.



The P-38 F/Gs that were replacing the P-39 in front line units were already in theater at the end of 1942 and General Kenney made up his mind because the P-39s performance in that theater was not suitable for what was actually needed and the P-38 was a flat out better aircraft for the mission required. He really didn't want the P-47 either but had to take them because P-38s were being diverted to North Africa and England (That's another story).

If you're going to make comparisons, why don't you compare what was being used at the time?!?!? P-39D or P-400!! The little bit of cherry picked advantage you're trying to show for the P-39N did not make up for the deficiencies in range and high altitude performance when compared to the P-38. For that matter let's compare the P-39M, N or Q to the P-38 J or L!

Now I will give credit were credit is due. The 39th an 9th FS while flying the P-39 really didn't do to badly and their experience carried over when they transitioned to the P-38. Tom Lynch and Curran Jones were two standouts with multiple credits. Pilot skill was probably the main factor of this success as Lynch became one of the top fighter pilots in the SWP and possibly could have scored higher than Richard Bong if he wasn't killed. Bottom Line V Fighter Command aerial victories soared after the P-38 entered combat.

Total agreement with the Soviets and the P-39, it was perfect for them and their operations and their combat record confirmed that despite leaving the gear box armor installed!

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## Shortround6 (May 27, 2021)

A short, incomplete and confusing "history" of the P-400 weight growth.

From Page 120 of "Cobra!" by Birch Mathews.

These are attributed to Bell model specifications. weight in pounds.

date.............................Empty...................useful load...................Gross...........................notes
Feb 1940....................4,524.......................1,325...........................5,849............................1 cannon, two machine guns
March 1940..............4,715.......................1,285............................6,000............................2machine guns added in each wing
May 1940.................5,149........................1,841............................7,000............................wing gun caliber increased
July 1940...................5,383.......................1,974.............................7,350...........................Armour and self-sealing tanks added
Jan 1941....................5,406.......................2,006.............................7,466...........................Minor empty and useful load increases
June 1941.................5,548........................2,087.............................7,635.........................Engine and fixed equipment weight increases
July 1941...................5,550.......................2,087..............................7,637..........................actual weight of Serial number AH 621

Now a few remarks about the 1325lb useful load in the first line. this starts my conclusions 
20mm cannon...................................131lb
37mm ammo.....................................32.4lb
2 .50 cal machine guns.................161lbs
.50 cal ammo....................................129lbs
Pilot.......................................................160lbs
oil..............................................................75lbs.
sub total ............................................688lbs

weight left for fuel..........................637lbs=106 US gallons.
Spaces in the wings would hold 170 gallons, the "tanks" were integral (seal up spaces in the wing, no separate tank/s)

The first 165 P-400s were ordered by the French in April of 1940, the French were supposed to supply the guns. 20mm, 13.2mm and 7.5mm.
The British don't get involved until May-June of 1940 when the design has to be redone (converted back to imperial measurements from Metric), use British/American guns and other accessories (radios, etc)
I don't know if the French asked for the four wing machine guns or if Bell offered to make the plane look better?

The 3rd line is rather suspect. The increase in wing gun caliber is from 7.5mm to 7.7mm
The French MAC 34 gun weighed 10.7kg. the Browning weighed about the same. Empty weight does not include the guns although it includes mounts and ammunition bins/tracks/boxes. Increase in useful load and gross weight cannot be blamed on change of guns or change in ammo supply except for around 230lbs.

Line 4 with the added armor and self sealing tanks might well be attributed to the British. US followed in Sept. This also cut the theoretical fuel capacity with full (instead of part filled ) tanks from 170 gallons to 120 galls (US gallons). Not to pick on the P-39. The P-36/Hawk and P-40s were NOT measured for performance with the tank behind the pilot filled at this point in time. 

The plane also gained weight due to increases in the engine weight and some of the other parts over which neither Bell or the British had any control over. The book the above list is from claims the weight of the Allison engine and accessories (which were government furnished equipment ) increase 380lbs from the start of design for the P-400 (well before French order) to the production versions.

So I ask *again *what were the items/equipment that the _British_ asked for in order to reduce the performance of the Aircobra I so they could get out of the contract.

every plane escalated in weight.

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## Shortround6 (May 27, 2021)

Glider said:


> And we still have the questions
> a) How much weight is involved adding the extra fuel plus its tanks and plumbing
> b) If the N was so good why was it replaced with the Q which had less performance
> c) You don't just rip out guns and add fuel
> d) what is the performance of the N with the extra weight. My guess is that it will be very similar to the P39Q which was a very similar aircraft, which in turn knocks great holes in your claim for the P39N being such a wonder weapon




Somewhere I had post with the listed performance of not only the P-39N but the P-39M (same plane with different reduction gear and propeller) the P-39Q, (same plane with different wing guns), the P-40 using the Allison with 9.6 supercharger gears and the P-51A using the Allison with 9.60 gears. 

The P-39N was way, way better in many categories, suspiciously so. like double digit percentage changes in climb. 

Maybe the test aircraft did perform that well, sometimes you get a plane where everything just "clicks" but what happens when you don't? 

If somebody made a graph with all the P-39 models in speed and climb from the D through Q all of the planes except the N would be somewhat closely gathered together in a bunch, with the lines for P-39N way out by themselves. There doesn't seem to be enough difference for the N to justify that change in performance.

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## buffnut453 (May 27, 2021)

Shortround6 said:


> Somewhere I had post with the listed performance of not only the P-39N but the P-39M (same plane with different reduction gear and propeller) the P-39Q, (same plane with different wing guns), the P-40 using the Allison with 9.6 supercharger gears and the P-51A using the Allison with 9.60 gears.
> 
> The P-39N was way, way better in many categories, suspiciously so. like double digit percentage changes in climb.
> 
> ...



But it's in the charts so it must be true!

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## Glider (May 27, 2021)

Shortround6 said:


> Somewhere I had post with the listed performance of not only the P-39N but the P-39M (same plane with different reduction gear and propeller) the P-39Q, (same plane with different wing guns), the P-40 using the Allison with 9.6 supercharger gears and the P-51A using the Allison with 9.60 gears.
> 
> The P-39N was way, way better in many categories, suspiciously so. like double digit percentage changes in climb.
> 
> ...



I totally agree that two aircraft the P39N and the P39Q were in many ways very similar and yet the performance was so different, to me it doesn't feel right.

However it seems to be the official performance so it isn't up to me to blame P39 for jumping on the P39N bandwagon. He needs something to support his belief.

What I can ask him is why the P39Q which was in many ways inferior in performance brought into service in the first place. Plus all the other questions that people have raised without response. The silence is deafening and yet speaks volumes

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## buffnut453 (May 27, 2021)

Glider said:


> What I can ask him is why the P39Q which was in many ways inferior in performance brought into service in the first place. Plus all the other questions that people have raised without response. The silence is deafening and yet speaks volumes



The deafening silence is replaced with constant repetition of his beliefs...the wing 30 cals were useless and should have been removed, same for the gearbox armour, no need for IFF, perfidious Albion unnecessarily increased the weight to get out of the contract etc, etc, etc.

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## FLYBOYJ (May 27, 2021)

What irks me is we clearly identified what manuals were being used and then he jumps back and forth from the N to the Q when the charts suit the discussion, then adds 120 gallons of fuel into the equation.

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## buffnut453 (May 27, 2021)

Questions that have been asked before but need to be asked again.

Yes, Kenney decided the P-39/P-400 was a dud. However, that was after some of the Pacific theatre airframes had the wing guns removed...and still the performance didn't cut it. If it had, and if the mod was worth doing, surely Kenney would have ordered all his P-39s and P-400s to be so modified? And yet, instead, he bins the P-39 in favour of the P-38. That screams to me that, for all the coulda-woulda-shoulda, the P-39 lacked performance for that theatre.

As for Europe, you'd definitely need the IFF...so no weight saving there. My observation that the early cannon-armed Spits retained 4x303s in the wings was blissfully ignored. Now we learn that the supposedly world-beating P-39N had a critical altitude some 5K below that of the Spitfire MkV which entered service in early 1941.

I'm willing to accept that the P-39 may have been a better performer than previously credited. However, it was NOT a world-beater. It could not compete in western Europe and, despite having the opportunity, it failed in the Pacific. Yes, the Soviets loved it and it was great for that theatre. It does not mean it was useful anywhere else.

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## Marcel (May 27, 2021)

buffnut453 said:


> It could not compete in western Europe and, despite having the opportunity, it failed in the Pacific. Yes, the Soviets loved it and it was great for that theatre. It does not mean it was useful anywhere else.


Last part, isn’t that true to an extent for most fighters in WW2? Like the Spitfire, it performed greatly in Europe, but didn’t have the same impact on the Pacific arena. Other way around for the Hellcat and the Corsair etc.

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## FLYBOYJ (May 27, 2021)

buffnut453 said:


> Questions that have been asked before but need to be asked again.
> 
> Yes, Kenney decided the P-39/P-400 was a dud. However, that was after some of the Pacific theatre airframes had the wing guns removed...and still the performance didn't cut it. If it had, and if the mod was worth doing, surely Kenney would have ordered all his P-39s and P-400s to be so modified? And yet, instead, he bins the P-39 in favour of the P-38. That screams to me that, for all the coulda-woulda-shoulda, the P-39 lacked performance for that theatre.



100% and if you read about Kenny, he was a stickler about performance and logistics. Look what he did to his medium bombers! If any mod "would have" helped the P-39 perfom better in the SWP, it "would have" been done.


buffnut453 said:


> As for Europe, you'd definitely need the IFF...so no weight saving there. My observation that the early cannon-armed Spits retained 4x303s in the wings was blissfully ignored. Now we learn that the supposedly world-beating P-39N had a critical altitude some 5K below that of the Spitfire MkV which entered service in early 1941.


Agree


buffnut453 said:


> I'm willing to accept that the P-39 may have been a better performer than previously credited. However, it was NOT a world-beater. It could not compete in western Europe and, despite having the opportunity, it failed in the Pacific. Yes, the Soviets loved it and it was great for that theatre. It does not mean it was useful anywhere else.


Agree 100%. I also believe that during it's development and early deployment the CG issues and false performance claims eventually pissed off the AAF. As we both know having worked a bit around aircraft, if you have an aircraft that is naturally tail heavy, this could be easily adjusted with ballast, but it seems that Bell initially refuse to accept the fact that the aircraft had C/G issues.

Although from Wiki and probably previously posted, sources are identified:

_The weight distribution of the P-39 was supposedly the reason for its tendency to enter a dangerous flat spin, a characteristic Soviet test pilots were able to demonstrate *to the skeptical manufacturer* who had been unable to reproduce the effect. After extensive tests, it was determined the spin could only be induced if the aircraft was improperly loaded, with no ammunition in the front compartment. *The flight manual noted a need to ballast the front ammunition compartment with the appropriate weight of shell casings to achieve a reasonable center of gravity.*_

_Soon after entering service, pilots began to report that "during flights of the P-39 in certain maneuvers, it tumbled end over end." Most of these events happened after the aircraft was stalled in a nose high attitude with considerable power applied. Concerned, Bell initiated a test program. Bell pilots made 86 separate efforts to reproduce the reported tumbling characteristics. In no case were they able to tumble the aircraft. In his autobiography veteran test and airshow pilot R.A. "Bob" Hoover provides an account of tumbling a P-39. He goes on to say that in hindsight, he was actually performing a Lomcovak, a now-common airshow maneuver, which he was also able to do in a Curtiss P-40. An informal study of the P-39's spinning characteristics was conducted in the NASA Langley Research Center 20-foot Free-Spinning Tunnel during the 1970s. A study of old reports showed that during earlier spin testing in the facility, the aircraft had never tumbled. However, it was noted that all testing had been done with a simulated full ammunition load, which drew the aircraft's center of gravity forward. After finding the original spin test model of the P-39 in storage, the new study first replicated the earlier testing, with consistent results. Then, *the model was re-ballasted to simulate a condition of no ammunition load, which moved the aircraft's center of gravity aft. Under these conditions, the model was found to often tumble when thrown into the tunnel.*_

And as mentioned earlier, Bell never learned from their mistakes:

_In February 1944, the Soviet government sent a highly experienced test pilot, Andrey G. Kochetkov, and an aviation engineer, Fyodor P. Suprun, to the Bell factories to participate in the development of the first production variant, the P-63A. *Initially ignored by Bell engineers*, Kochetkov's expert testing of the machine's spin characteristics (which led to airframe buckling) eventually led to a significant Soviet role in the development. After flat spin recovery proved impossible, and upon Kochetkov's making a final recommendation that pilots should bail out upon entering such a spin, he received a commendation from the Irving Parachute Company.* The Kingcobra's maximum aft CG was moved forward to facilitate recovery from spins*._

Personally I believe that Bell engineers knew they couldn't get the speeds promised by their management to the AAF so they intentionally kept the aircraft tail heavy to squeeze a few more MPH out of the aircraft and that's why they were so reluctant to listen to the Soviets - this is just my personal opinion.

Now fast forward a bit - the post war Thompson Trophy Races. the P-39s and P-63s operated for racing did real well with a P-39 winning the 1946 race. Although you need the performance, there's a lot more pilot skill involved as you're flying "a line" without cutting a pylon. Aside from souping up engines and modifying airframes, the other thing you're going to do to get the aircraft to fly a little faster is make the aircraft tail heavy....

Low and tail heavy, the P-39 and P-63 made perfect racers!

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## Peter Gunn (May 27, 2021)

Totally agree about Gen. Kenney, as I said in post #1612, I'm pretty sure he was aware of what changes had been made to any aircraft in the AAF inventory that were considered combat capable. 

Also agree re: medium bombers, with that in mind and knowing that he was willing to innovate just about anything to get the job done, if there was a way to improve the P-39's performance he would have his "Kids" try it.

That he ditched the 39 in favor of the Lightning ASAP, well, if that doesn't speak volumes to you about the respective aircraft, I don't know what does.

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## eagledad (May 27, 2021)

Gentlemen,

Let us look the high altitude performance of the P-39, by looking at the actual experience of the 350th FG. The group flew from England to North Africa with a mixture of P-400’s and P-39L’s and entered combat in North Africa in Jan of 1943. *P-39N*’s appeared some time during April/May 1943.

The unit defended the coast of Algeria during the summer and fall of 1943. Yet despite the presence of some P-39N’s, each squadron in the group was assigned two P-38s to intercept and destroy high-flying Luftwaffe reconnaissance aircraft sent to photograph the allied invasion fleet gathering along the North African coast for the invasion of Sicily..

If the *P-39N* had such sterling high altitude performance, why would the Air Force send the group 6 P-38’s to intercept the high-flying German photo ships? Remember, we are not talking charts or theory, we are talking about what actually happened.

Sources
350th Fighter Group — Wikipedia Republished // WIKI 2
350thfghonor_roll (raf-112-squadron.org)

Eagledad

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## buffnut453 (May 27, 2021)

Peter Gunn said:


> That he ditched the 39 in favor of the Lightning ASAP, well, if that doesn't speak volumes to you about the respective aircraft, I don't know what does.



It's all part of the great conspiracy against the P-39, which included Perfidious Albion and persists to this very day in all the negative press that the P-39 receives. We're all mistaken in our understanding of the P-39 but our resident expert, alone, has recognized the truth.

I'm off to check websites about 5G cell towers causing COVID 19!!

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## special ed (May 27, 2021)

I understand it was really P-39s that intercepted Yamamoto but it was reported as P-38s to keep the P-39s ability secret.

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## Peter Gunn (May 27, 2021)

special ed said:


> I understand it was really P-39s that intercepted Yamamoto but it was reported as P-38s to keep the P-39s ability secret.


You left out its ability as a night fighter/bomber stopping battleship bombardments of Henderson Field on Guadalcanal, torpedoing Musashi off Leyte, mining Tokyo Bay and dropping both A bombs.

Just sayin'.

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## SaparotRob (May 27, 2021)

special ed said:


> I understand it was really P-39s that intercepted Yamamoto but it was reported as P-38s to keep the P-39s ability secret.


The P-38’s just flew top cover over the P-39’s on that interception. This was in case the IJN was flying P-39’s captured from the Soviets.

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## Marcel (May 27, 2021)

buffnut453 said:


> I'm off to check websites about 5G cell towers causing COVID 19!!


Old news, it's now believed that an American professor at Harvard created the virus and secretly sold it to China. Can't believe you're that outdated on your conspiracy theories

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## pbehn (May 27, 2021)

buffnut453 said:


> It's all part of the great conspiracy against the P-39, which included Perfidious Albion and persists to this very day in all the negative press that the P-39 receives. We're all mistaken in our understanding of the P-39 but our resident expert, alone, has recognized the truth.


That is the basis of the premise. If the British had accepted the P-39C instead of making up stuff to get out of a contract, the very similar slightly modified P-39N (which only had a different "impeller" whatever that is) could have won the Battle of Britain and gone on to be the saviour of the western world.

Stating the P-39N of 1943 had impressive performance is only in comparison to earlier P-39s, the Spitfire MXIV was in service in 1943. If a Spitfire IX needed extended wings, stripping out armour, some guns and its radio to get to 42,000ft I am not convinced any P-39 had a service ceiling of 38,000ft.

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## Thumpalumpacus (May 27, 2021)

Marcel said:


> Old news, it's now believed that an American professor at Harvard created the virus and secretly sold it to China. Can't believe you're that outdated on your conspiracy theories



What virus?

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## Marcel (May 27, 2021)

Thumpalumpacus said:


> What virus?


The one that the professor sold to China of course..

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## Thumpalumpacus (May 27, 2021)

Marcel said:


> The one that the professor sold to China of course..



Look, 600,000 crisis-actors can't be wrong!

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## Schweik (May 27, 2021)

gordonm1 said:


> This one looked like 6 50's with only two firing on the left side like #3 was jammed.



Or they didn't have all the guns in there, or all the guns loaded


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## P-39 Expert (May 27, 2021)

wuzak said:


> The reduction from 120 USG to 87 USG was to reduce weight, like you've been banging on about for years now.
> 
> The N and Q were produced with 87 USG from the factory. Kits could be applied in the field to bring them up to 120USG, but how many were fitted and where? *The first 160+ N models had 120gal internal fuel. P-39Q had full 120gal fuel from the -10 model through the end of production -30 model. Don't know how many kits were fitted.*
> 
> Did the wings have the facilities for extra fuel tanks where the guns were mounted? *Wings had the SPACE to mount fuel tanks where the wing guns were mounted.*


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## Schweik (May 27, 2021)

Oh jeez time to unsub this thread again

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## P-39 Expert (May 27, 2021)

Peter Gunn said:


> So much to parse out, well...
> 
> 
> 
> ...


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## P-39 Expert (May 27, 2021)

Glider said:


> And we still have the questions
> a) How much weight is involved adding the extra fuel plus its tanks and plumbing *6 pounds per gallon of fuel and 2 pounds per gallon for tanks. 30 gallons = 240lbs.*
> b) If the N was so good why was it replaced with the Q which had less performance *Absolutely no earthly idea. Why were the D/F/K/L so heavy for available power when they could have been easily and quickly lightened? Why add external gun pods that produce drag? Especially when the podded 50s weighed almost twice as much as the internal 30s? These are questions I can't answer. *
> c) You don't just rip out guns and add fuel *No, you remove the guns, ammo boxes, chargers and heaters and replace them with wing fuel tanks. The P-38 removed wing intercoolers and replaced them with fuel tanks. Certainly could be done.*
> d) what is the performance of the N with the extra weight. My guess is that it will be very similar to the P39Q which was a very similar aircraft, which in turn knocks great holes in your claim for the P39N being such a wonder weapon *Go to wwiiaircraftperformance.org and look up the P-39N and Q. Just reinforces my claim.*



Please expand above.


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## P-39 Expert (May 27, 2021)

FLYBOYJ said:


> "Could have, would have, should have" once again you're cherry picking. I think you know as well as I the AAF units in the SWP (80th FG, 35th FS for example) that were using *P-39Ds* and *P-400s* did not operate with 120 gallon fuel tanks. Even with the extra fuel the P-38 F/G, let alone the J easily outranged the P-39. So please, stop trying to throw "what ifs" into what actually happened. *Sorry, all P-39Ds and P-400s had full 120gal internal fuel.*
> 
> 
> Could have, would have, should have."  *Easily lightened at forward bases.*
> ...


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## pbehn (May 27, 2021)

P-39 Expert said:


> *Absolutely no earthly idea. Why were the D/F/K/L so heavy for available power when they could have been easily and quickly lightened? Why add external gun pods that produce drag? Especially when the podded 50s weighed almost twice as much as the internal 30s? These are questions I can't answer.*


How can you continue to argue this? You say yourself that the P-51 was a ton heavier and it was accepted with any Allison or RR engine put in it. All airforces wanted to increase firepower, if they couldnt put them in the wings they put them in pods, 20mm cannon are much more than 2 times the weight of 0.303mgs, no now you can answer those questions in future, cant you?

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## P-39 Expert (May 27, 2021)

Shortround6 said:


> A short, incomplete and confusing "history" of the P-400 weight growth.
> 
> From Page 120 of "Cobra!" by Birch Mathews.
> 
> ...


Please expand above.


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## pbehn (May 27, 2021)

P-39 Expert said:


> So I ask *again *what were the items/equipment that the _British_ asked for in order to reduce the performance of the Aircobra I so they could get out of the contract.
> 
> *Again, 4x30calMGs with 1000rounds per gun (400lbs including mounts, chargers, heaters and ammo boxes), 260lbs of armor plate/glass when 125lbs would have been plenty, and an IFF radio (110lbs) that wouldn't be needed in NG until 1943 because there was no radar until then. Total 645lbs.*


The British specified 8 x 0.303 mgs for its S/E fighters, this was changed to 4x 20mm cannon in 1940/41. What do you consider to be a reasonable armament for a fighter in 1941? The IFF radio may not have been needed in NG but was in UK, which is the topic of discussion. The P-39 needed armour behind and in front of the pilot because of engine location, how do you come up with a weight for armour?


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## P-39 Expert (May 27, 2021)

FLYBOYJ said:


> 100% and if you read about Kenny, he was a stickler about performance and logistics. Look what he did to his medium bombers! If any mod "would have" helped the P-39 perfom better in the SWP, it "would have" been done. *Actually was done at Guadalcanal. K/L models were reduced by 600lbs+ of unnecessary/redundant equipment and could then fight at 27000ft. But that was in October and P-38s were arriving shortly. Why wait so long?*
> 
> Agree
> 
> ...


Please expand above.


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## FLYBOYJ (May 27, 2021)

P-39 Expert said:


> Sorry, all P-39Ds and P-400s had full 120gal internal fuel.


So then they were even heavier and with worse performance than what we've been working to, right?!?!?!


P-39 Expert said:


> Easily lightened at forward bases.
> 
> P-39D and P-400 would have significantly better performance if lightened.


Could have, would have, should have."  *If it was easily done why wasn't it?!?!?*


P-39 Expert said:


> Compare the M/N/Q with P-38J/L? There were no P-38J/Ls during P-39M/N/Q production.


Just like there were no P-39Ns in the SWP in late 1942! P-38Js started production in the summer of 43. An even better Lightning was coming and leadership at the time knew it. 


P-39 Expert said:


> P-38J/L came after the Q had finished production. Better to compare the P-38F/G that were available at the same time.


And better compare the P-38F/G with the P-39D and P-400. It's apparent General Kenny did!!!


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## P-39 Expert (May 27, 2021)

pbehn said:


> How can you continue to argue this? You say yourself that the P-51 was a ton heavier and it was accepted with any Allison or RR engine put in it. All airforces wanted to increase firepower, if they couldnt put them in the wings they put them in pods, 20mm cannon are much more than 2 times the weight of 0.303mgs, no now you can answer those questions in future, cant you?


Biggest drawback to 30calMG is effective range was only 200 yards (AHT). All air forces wanted to increase firepower but it had to be used judiciously. Otherwise why not just put 10 50calMGs on every fighter? Because it would have weighed too much. P-51A/B/C, FM2 Wildcat and F8F Bearcat had reduced guns to four from six or eight on previous fighters. Four was deemed sufficient for the time. P-39 nose armament (cannon and twin 50cal MGs) produced more firepower than four 50cal MGs.


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## FLYBOYJ (May 27, 2021)

P-39 Expert said:


> Actually was done at Guadalcanal. K/L models were reduced by 600lbs+ of unnecessary/redundant equipment and could then fight at 27000ft. But that was in October and P-38s were arriving shortly. Why wait so long?



You said it yourself - the P-38s were arriving.


P-39 Expert said:


> Keep beating this tail heavy horse to death, it suits your narrative.


*I'm learning from example!!!!*



P-39 Expert said:


> No P-39 ever went into combat with NO NOSE AMMO.


 But as stated, they should have came home with none either


P-39 Expert said:


> When nose ammo was expended the shell casings remained which achieved a reasonable center of gravity.


And why was that done?!? And why did Bell ignore known issues with the C/G? Why did they ignore the Russians at the beginning of P-63 production?!?!



P-39 Expert said:


> Chuck Yeager said it had excellent handling characteristics and people who said otherwise had never flown the plane.



And as we know he was arguably one of the best combat pilots of WW2 but he was just one man and didn't have to fly it at Port Moresby against the Zero or Oscar!!

And agree, the aircraft had "excellent handling characteristics " but it had many other issues that caused it to go second string.

Except for the Russians - the Russians liked it!  Oh - and it was a great post-war race plane!

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## pbehn (May 27, 2021)

P-39 Expert said:


> *Keep beating this tail heavy horse to death, it suits your narrative. No P-39 ever went into combat with NO NOSE AMMO. When nose ammo was expended the shell casings remained which achieved a reasonable center of gravity. Chuck Yeager said it had excellent handling characteristics and people who said otherwise had never flown the plane.* .


It is not a dead horse, and Yeager never flew it in combat.

from here The Bell P-39 Airacobra & P-63 Kingcobra 
In USAAF hands, its record was mixed: it was sturdy and well-armed, but its high-altitude performance was poor and its centrally-mounted engine led to handling problems. The difficulty was that after ammunition was expended, the aircraft's CG shifted back so that the aircraft was inclined to fly tail-first, throwing it into a flat spin from which recovery was problematic. Bailing out under such conditions was also troublesome, because the pilot had a tendency to hit the tail. Even if recovery were possible, the spin had a tendency to warp the aircraft's tail, rendering the controls useless, which is why the P-39Q-25 introduced a reinforced rear fuselage.




Another reason was that the Red Air Force thoroughly evaluated the Airacobra before putting it into service, finding out the hard way about its vicious spin characteristics, with several test pilots killed. The faults were documented, however, with rules for flying the aircraft written up for operational pilots -- they were warned to never perform aerobatics if they had expended their ammunition -- and training implemented to make sure P-39 pilots knew how to avoid spins and, when possible, head them off before the point of no return. Procedures had to be devised for maintenance in extreme cold conditions. Bell engineers went to the USSR to assist the Soviets in qualifying the P-39, obtaining feedback for refinements to the design.

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## pbehn (May 27, 2021)

P-39 Expert said:


> Biggest drawback to 30calMG is effective range was only 200 yards (AHT). All air forces wanted to increase firepower but it had to be used judiciously. Otherwise why not just put 10 50calMGs on every fighter? Because it would have weighed too much. P-51A/B/C, FM2 Wildcat and F8F Bearcat had reduced guns to four from six or eight on previous fighters. Four was deemed sufficient for the time. P-39 nose armament (cannon and twin 50cal MGs) produced more firepower than four 50cal MGs.


At what time? The Mustang MkI had 4x 0.5" and 4x 0.3" The Mustang MkIA had 4x20mm. Some Spitfires in the Med had 4x20mm cannon and 4x0.303mgs. Only the P-51B/C had 4x0.5 the D went to 6x 0.5"

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## Thumpalumpacus (May 27, 2021)

Is it just me or does anyone else wish that 

 P-39 Expert
would learn how to use the quoting system properly?

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## FLYBOYJ (May 27, 2021)

pbehn said:


> It is not a dead horse, and Yeager never flew it in combat.
> 
> from here The Bell P-39 Airacobra & P-63 Kingcobra
> In USAAF hands, its record was mixed: it was sturdy and well-armed, but its high-altitude performance was poor and its centrally-mounted engine led to handling problems. The difficulty was that after ammunition was expended, the aircraft's CG shifted back so that the aircraft was inclined to fly tail-first, throwing it into a flat spin from which recovery was problematic. Bailing out under such conditions was also troublesome, because the pilot had a tendency to hit the tail. Even if recovery were possible, the spin had a tendency to warp the aircraft's tail, rendering the controls useless, which is why the P-39Q-25 introduced a reinforced rear fuselage.
> ...



From your reference;

_*"The P-39D left something to be desired in service, suffering from a range of teething problems such as gear that was unreliable or froze up and other deficiencies. Deficiencies were addressed in subsequent variants, initially with a confusing list of P-39 variants built in small or relatively limited numbers." and*_

_*"However, British expectations of the "Airacobra I" -- as it was designated in Royal Air Force (RAF) service -- had been set by performance figures established by the unarmed and unarmored XP-39 prototype. On evaluation, the P-400 turned out to be about 10% slower than advertised, and of course its high-altitude performance was pathetic. It should be noted, however, that Bell engineers were correct in believing the mid-mounted engine was good for maneuverability, the RAF report concluding that an Airacobra could easily out-turn a Messerchmitt Bf 109."*_

Give credit where credit is due!

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## FLYBOYJ (May 27, 2021)

Thumpalumpacus said:


> Is it just me or does anyone else wish that
> 
> P-39 Expert
> would learn how to use the quoting system properly?



Agree - this is going to become an issue


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## SaparotRob (May 27, 2021)

Thumpalumpacus said:


> Is it just me or does anyone else wish that
> 
> P-39 Expert
> would learn how to use the quoting system properly?


I still haven't figured it out. Like how to quote just one sentence instead of the whole post.


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## FLYBOYJ (May 27, 2021)

And a little more about the C/G and spins:

_Another reason was that the Red Air Force thoroughly evaluated the Airacobra before putting it into service, finding out the hard way about its vicious spin characteristics, with several test pilots killed. The faults were documented, however, with rules for flying the aircraft written up for operational pilots -- *they were warned to never perform aerobatics if they had expended their ammunition *-- and training implemented to make sure P-39 pilots knew how to avoid spins and, when possible, head them off before the point of no return. Procedures had to be devised for maintenance in extreme cold conditions. Bell engineers went to the USSR to assist the Soviets in qualifying the P-39, obtaining feedback for refinements to the design._

*Comrade - no victory roll for you! *

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## Thumpalumpacus (May 27, 2021)

SaparotRob said:


> I still haven't figured it out. Like how to quote just one sentence instead of the whole post.



Just put "[/quote]" at the end of the part you want to reference, and delete the rest. Or separate it into another paragraph. If you want to learn that we can take it to PM, it's easy but there's no sense in interrupting the flogging of a deceased equine.


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## pbehn (May 27, 2021)

FLYBOYJ said:


> From your reference;
> 
> _*"The P-39D left something to be desired in service, suffering from a range of teething problems such as gear that was unreliable or froze up and other deficiencies. Deficiencies were addressed in subsequent variants, initially with a confusing list of P-39 variants built in small or relatively limited numbers." and*_
> 
> ...


I agree, the decision to send P-39s to Russia was political and logistical. On Baughers site it states (to paraphrase) that the British would have taken more, but they were already ordered on Lend Lease but after June 1941 Russias need was greater and after December 1941 the USAs short term need was greatest of all. I wish I could find that article again on the Russians commissioning the P-39, it involved getting the drawings out and stripping one down to the nuts and bolts to decide how to service it and what with (greases lubricants etc) and where to install drains to drain oil coolants etc so they didnt freeze in extreme cold.

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## pbehn (May 27, 2021)

SaparotRob said:


> I still haven't figured it out. Like how to quote just one sentence instead of the whole post.


Just do the quote and then delete out what you dont want. If quoting something that is already a quote an so doesnt appear, press quote/reply copy what you want to quote into the gap in the brackets.

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## Milosh (May 27, 2021)

SaparotRob said:


> I still haven't figured it out. Like how to quote just one sentence instead of the whole post.



Just highlight what you want to quote. A popup appears with 'Quote' or 'Reply'.

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## Dimlee (May 27, 2021)

Glider said:


> Interesting information and something I hadn't heard before. I admit my first thought was the most senior person would probably be the NKVD Commissar, but that's just me.



People of the secret services have accompanied most of the delegations which were sent abroad. But they kept a lower profile usually and their authority was limited to security and ideology. Unless they were stupid.

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## Marcel (May 27, 2021)

Thumpalumpacus said:


> If you want to learn that we can take it to PM, it's easy but there's no sense in interrupting the flogging of a deceased equine.


Actually, I think it would enhance the quality of the thread if explained it here

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## Dimlee (May 27, 2021)

pbehn said:


> Dimlee
> Not the article I read, but this does state Soviet pilots were training with 601 squadron, not unreasonable to think they had a senior person in charge of it all.
> 
> *Airacobras in the Soviet Union *
> Quote. Soviet pilots had first seen the Airacobra in Great Britain, when a group of pilots was sent to No. 601 Squadron at RAF Duxford for training. The British had found the Airacobra unsuitable for their own use and were more than happy to turn over their Airacobras to the Soviets, and some 212 of the 675 Airacobra Is ordered by the RAF were diverted to the USSR. The Airacobras first entered service with the Soviet Air Force in May of 1942.



Good find, thank you. I have missed this information when studied P-39 history 20 years ago or so.

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## Thumpalumpacus (May 27, 2021)

Marcel said:


> Actually, I think it would enhance the quality of the thread if explained it here



At least the thread will have _some_ usefulness!

ETA: Aside from killing time, of course.


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## Greg Boeser (May 27, 2021)

Just 920 more pages and we will have eclipsed the _picture of the day_ thread.

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## pbehn (May 27, 2021)

Greg Boeser said:


> Just 920 more pages and we will have eclipsed the _picture of the day_ thread.


I thought we made some progress today.

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## GregP (May 27, 2021)

But, we've thought that before and, alas, it was not to be ...

This reminds me of Exidor from Mork and Mindy. He ALMOST made sense and then rapidly departed after seeming very logical only moments before.


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## tyrodtom (May 27, 2021)

This thread is sort of like a early Andy Koffman comedy routine .
Where he would just do something like read a boring book on stage, just to see how long the audience would take it.

The joke is on us.

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## GregP (May 28, 2021)

I spoke with someone who has flown both a P-39 and a P-63 about the radio on top of the engine cover. 

Unfortunately, he doesn't know how hot it gets because neither of the aircraft he flew had a functional radio in that area and there was absolutely no reason to check the heat there. Everyone expects an engine to get pretty warm and trying to check the temperature of a surface next to an engine that has just been operated at temperature is like touching and exhaust pipe to see if it gets hot ... nobody does that. Also, access to the surface in question is not something a pilot would normally need right after a flight. A mechanic might, but only if there was an engine complaint or engine service was needed / required after the flight.

So, unknown at this time.

The P-63A seems like a pretty good climber at 75" MAP, with a rate of around 3,680 fpm at 2000 to 6000 feet and still climbing at 2,680 fpm at 23,000 feet. Service ceiling was 40,400 feet. Speed was 400 mph at 16,000 feet and 378 mph at 25,000 feet. Not too bad, but the test was run on 1945, when other airplanes in service were a bit faster. Still, it looks like the P-63A had decent performance at decent altitude, coupled with better roll than all other fighters in service with the U.S.A. From wwiiaircraftperformance.org. No test results for range there. To me, the P-63 was optimized for Russian operation. They only needed short range due to their method of employment to effect air support from close to the front lines for both ground and air missions. 

P-63A climb at normal power was around 2,500 fpm, not much different from other front-line fighters. Their best climb rates were also at high MAP, as everyone knows. The tests were run at weights around 8,168 to 8,500 pounds.

Testing mentioned that the airplane had a dangerous characteristic in that the stick force per g was dangerously low at the CG flown. They tried a bob weight (as in the P-51) and it helped, but the flight restrictions remained in effect and it was stated that an acceptable solution was to increase the stick force per g without a bob weight. So, it appears that the P-63A has some rearward CG issues, as we all know it did and have discussed. 

The P-63 was flown in the 1944 Fighter Conference and most of us can access that information. My copy has pilot comments that say:

Visibility to the rear was not very good, but that if the visibility could be improved, it would be good from a performance standpoint. Comments said it was not up to most other fighters, but was better than "the old P-39." It needed an aileron trim tab. Engine roughness and vibration was miserable. Heavy aileron forces, but the airplane was "what the P-39 OUGHT TO HAVE BEEN, too late now" (exact words). Excellent at high speeds for maneuverability. Visibility is good; stick forces light (so, some pilots disagreed with one another). Climb is good at normal power, excellent above normal power. Not as good as an F6F or P-51 as an all-round fighter. Not suitable for combat.

So, pilot comments are a mixed bag. Of 21 pilots, 1 rated if good for combat, 4 rated it bad, 6 chose "other" and made comments, and 10 left the combat qualities blank. All in all, they seemed to like the airplane, but not really for combat.

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## FLYBOYJ (May 28, 2021)

GregP said:


> I spoke with someone who has flown both a P-39 and a P-63 about the radio on top of the engine cover.
> 
> Unfortunately, he doesn't know how hot it gets because neither of the aircraft he flew had a functional radio in that area and there was absolutely no reason to check the heat there. Everyone expects an engine to get pretty warm and trying to check the temperature of a surface next to an engine that has just been operated at temperature is like touching and exhaust pipe to see if it gets hot ... nobody does that. Also, access to the surface in question is not something a pilot would normally need right after a flight. A mechanic might, but only if there was an engine complaint or engine service was needed / required after the flight.
> 
> ...



Great info, many thanks Greg! Just beware of the Platypus!

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## GrauGeist (May 28, 2021)

Ok, soooo...
If the P-39 was so awesome, why did they make the P-63?

Then again, I suppose that question may fall into the mystery category alongside the age-old question of "if Teflon is non-stick, how does it stay on the pan?"

The world may never know...

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## Graeme (May 28, 2021)

Interesting article in Aeroplane Monthly (March 1995) by Ann Welch who served with the Air Transport Auxiliary and flew Airacobras.
She was not impressed.

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## GregP (May 28, 2021)

airspeed discrepancies could easily point to pitot-static leaks. I'd believe that more than just manufacturing differences. Maybe loose hose clamps?


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## P-39 Expert (May 28, 2021)

GregP said:


> I spoke with someone who has flown both a P-39 and a P-63 about the radio on top of the engine cover.
> 
> Unfortunately, he doesn't know how hot it gets because neither of the aircraft he flew had a functional radio in that area and there was absolutely no reason to check the heat there. Everyone expects an engine to get pretty warm and trying to check the temperature of a surface next to an engine that has just been operated at temperature is like touching and exhaust pipe to see if it gets hot ... nobody does that. Also, access to the surface in question is not something a pilot would normally need right after a flight. A mechanic might, but only if there was an engine complaint or engine service was needed / required after the flight.
> 
> ...


What I never understood about the P-63 was with a 15% larger wing how it only managed 130+ gallons of fuel. And why podded machine guns? Plenty of room for more fuel or armament in that big wing.


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## FLYBOYJ (May 28, 2021)

GregP said:


> All in all, they seemed to like the airplane, but not really for combat.



Great for air racing!

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## Peter Gunn (May 28, 2021)

SaparotRob said:


> I still haven't figured it out.



It's



SaparotRob said:


> Like how to quote just one sentence



an



SaparotRob said:


> instead of the whole post.



art.

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## Peter Gunn (May 28, 2021)

GregP said:


> So, pilot comments are a mixed bag. Of 21 pilots, 1 rated if good for combat, 4 rated it bad, 6 chose "other" and made comments, and 10 left the combat qualities blank. *All in all, they seemed to like the airplane, but not really for combat.*


 My bold/italics.

I think this sums up the P-39/63 pretty well. When I read Yeager's autobiography back in the '80's, I got the impression it was a pretty good plane to fly, but not to fight in. Although he did say that he would have happily gone to war in it if he had to. Now a guy like that would probably do alright in it but I doubt he would want to take it above 20,000 feet and fight. Who would?

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## vikingBerserker (May 28, 2021)

Perhaps this is my simplistic thinking, but if you have multiple countries using this fighter (a number of which were fighting for their lives) and if there was a way to make it a top notch fighter as opposed to expending critical resources and TIME you don't have to build an entirely new one, I would think they would have devoted the time and resources to do so, but they did not which leads me to think it was probably as good as it could be at that time.

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## tyrodtom (May 28, 2021)

GregP said:


> I spoke with someone who has flown both a P-39 and a P-63 about the radio on top of the engine cover.
> 
> Unfortunately, he doesn't know how hot it gets because neither of the aircraft he flew had a functional radio in that area and there was absolutely no reason to check the heat there. Everyone expects an engine to get pretty warm and trying to check the temperature of a surface next to an engine that has just been operated at temperature is like touching and exhaust pipe to see if it gets hot ... nobody does that. Also, access to the surface in question is not something a pilot would normally need right after a flight. A mechanic might, but only if there was an engine complaint or engine service was needed / required after the flight.



There was a armored glass panel right behind the pilot, in every picture it looks like it fit tight to the canopy.
I don't see how anyone could even reach back there to touch that panel above the engine, let alone service a radio.
Must have been a bitch to get to that area behind the pilot when that armor glass was installed.

Sort of a puzzle, you've got a aircraft with a fair 360 view canopy, then you put a radio behind him and block the view from the rear.
Look at the pictures where what looks like all the radio ( not just the IFF) is installed behind the pilot.
Just how well do you think he could see to the rear ?

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## SaparotRob (May 28, 2021)

Peter Gunn said:


> My bold/italics.
> 
> Now a guy like that would probably do alright in it but I doubt he would want to take it above 20,000 feet and fight. Who would?


Maybe Chuck Yeager would take it into combat but would he want his wingman to be flying one?

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## SaparotRob (May 28, 2021)

Hey Gunn, I almost got it right!

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## P-39 Expert (May 28, 2021)

Can we get back to the ranges quoted in the pilot's manual?

The fuel from sea level figure from the Takeoff, Climb and Landing chart should not be used to compute range, or the instructions in the Flight Operation Instruction Chart (range chart) would say so.

The ranges in the range chart have already been adjusted down to reflect both the fuel used in climbing from 5000ft and the miles of range gained during the climb.


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## Glider (May 28, 2021)

P-39 Expert said:


> Please expand above.



Actually I (and in my opinion no one else) needs to expand on anything.

Lets sum it up

The P39N1 operating at temperatures that were higher than normal acceptable operating levels turned in a good performance but it should be noted that this was at the cost of a very low range and without any payload. This operating at above normal temperatures is no small thing. You can get away with it for a certain period of time but sooner or later it will bite you.

The Typhoon another aircraft of a similar era matched the performance of the P39N1 in the early years and comfortably exceed the performance of the P39N1 from early1944 on. It should also be noted that the Typhoon carrying 2,000lb of bombs had a greater range than the P39N1 when clean and about 1,000 miles with drop tanks.

There is no doubt that the P39N1 has a better performance than the Typhoon at 25,000 ft but the range of the P39N1 would be close to miserable at that altitude and the chances of a successful interception low, make that very low if your spotted when climbing up.
In the real world if you were fighting Typhoons then at 25,000 ft you would be taking on the Spit IX and good luck with that. Even the Spitfire had a better range than any version of the P39 from late 1944 on, and no one would claim that the range of the Spitfire was it's strength.

You can of course add additional fuel tanks but then you effectively end up with the P39Q which has a much lower performance. You can of course tweak the performance by removing the two 0.5 in the wings of the P39Q but that would make little difference to the speed. Worth noting that the Me109 with 2 x 20mm underwing guns only lost 8mph when carrying them and the 0.5 was a lot smaller so the difference is likely to be no more than 4 mph.

You have a lot of fantasies about how to change the performance of the P39. New engines, removing armour, adding fuel tanks, deleting equipment with hardly any evidence (because there is next to none that exists) to back up your assertions that such changes were Easy, Obvious, Simple, Straight forward. Yet has been pointed out to you on any number of occasions, tens of thousands of flight engineers, hundreds of engineers/designers at Bell and thousands of pilots many of whom fought and died in the P39. Educated, trained and experienced people who knew every bolt, cable and rivet in the aircraft didn't make those changes. Why, because they knew it couldn't be done. Yet you, with no training or experience know better than all these people

I was an Artificer in the Fleet Air Arm specialising in airframes and engines. This was a training regime that took five years and I know that your statements and assumptions are puerile. I use that word deliberately because if you look up the definition, it fits. There are many others on this forum with infinitely more training and experience than myself in aviation, these are people I listen too and learn from, people who have also told you with supporting evidence that its impossible. Yet you again, know better than all of us.

No, we do not need to expand , you need to expand to give evidence to support your massive assumptions, and/or explain why you have such omnipotent knowledge on this subject.

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## Shortround6 (May 28, 2021)

P-39 Expert said:


> Can we get back to the ranges quoted in the pilot's manual?
> 
> The fuel from sea level figure from the Takeoff, Climb and Landing chart should not be used to compute range, or the instructions in the Flight Operation Instruction Chart (range chart) would say so.
> 
> The ranges in the range chart have already been adjusted down to reflect both the fuel used in climbing from 5000ft and the miles of range gained during the climb.



It depends on how you want to compute the range.

The USAAF, rightly or wrongly, in their comparisons charts *did not *credit any horizontal movement in the climb to 25,000 ft cruising altitude. This was to allow for forming up and rendezvousing with the bombers. If you want to come up a figure for range/radius to compare to the planes listed in the chart then you have to use the conditions the chart says. 

You have yet to explain how a plane that reaches 5000ft gets to 20,000-25,000 without using addition fuel over and above the fuel needed to cruise at 5,000. 

Please show in the manual or on the chart*s *where it says " ranges in the range chart have already been adjusted down to reflect both the fuel used in climbing from 5000ft and the miles of range gained during the climb" It sure doesn't say that on the P-39Q charts. 


If you wish to use your method of range commutation then please compute the ranges for the planes you are comparing to the same way. 

BTW, everybody should read the fine print at the bottom of the Climb charts for all aircraft. 

For some reason the US *did not *use standard temperature and pressure for these charts. They used 0 degrees C (32 degrees F) instead of 15 degrees C/59 degrees F. 
Some charts, like the P-39Q chart leave the correction blank, other charts say 10% increase in climb time for *EVERY 10 degrees C *above 0.

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## FLYBOYJ (May 28, 2021)

P-39 Expert said:


> Can we get back to the ranges quoted in the pilot's manual?
> 
> The fuel from sea level figure from the Takeoff, Climb and Landing chart should not be used to compute range, or the instructions in the Flight Operation Instruction Chart (range chart) would say so.
> 
> The ranges in the range chart have already been adjusted down to reflect both the fuel used in climbing from 5000ft and the miles of range gained during the climb.



(Beating the horse)

So you're trying to tell us that if I'm going to plan a mission, I plan to fly to 5000' then plan my range? What if I want to take off and climb to 10,000 feet. what if I climb to 5000 feet and then decide to go 20,000? Do I do this flying in circles? Do I disregard the climb gradient? Can you show us where it specifically says on the chart* "the ranges in the range chart have already been adjusted down to reflect both the fuel used in climbing from 5000ft and the miles of range gained during the climb"?*

**


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## FLYBOYJ (May 28, 2021)

Shortround6 said:


> It depends on how you want to compute the range.
> 
> The USAAF, rightly or wrongly, in their comparisons charts *did not *credit any horizontal movement in the climb to 25,000 ft cruising altitude. This was to allow for forming up and rendezvousing with the bombers. If you want to come up a figure for range/radius to compare to the planes listed in the chart then you have to use the conditions the chart says.
> 
> ...



You beat me to the punch!


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## Shortround6 (May 28, 2021)

"*Wings had the SPACE to mount fuel tanks where the wing guns were mounted.* "

You would have space in two dimensions. Now the question is it was smart.





Fuel tanks fitted between the forward spar and the Main spar, the distance narrows between the spars the further out you go.
The wing gets thinner there further out you go. The wing at the W-2 position indicated on the drawing is less than 8 inches thick at max, it is a bit thicker where the machine guns are.

Self sealing fuel tank material is pretty much constant thickness and weight per sq ft. A long, skinny, thin tank is going to use a lot more self sealing material than a short fat tank of the same capacity. a tank with an assumed thickness of 6.5 inches (allowing for Self sealing material as a guess, corrections welcome) you need almost 2 sq feet of tank to hold *ONE *gallon.
Granted that is worst case, but it shows that fuel tanks in the last few feet of a wing are poor proposition. Lots of tank weight for not that big an increase in fuel. A tank at mid point in the wing may hold 50 % more fuel per sq ft of wing area than tank in the outer wing for the same weight of self sealing material due to being thicker.
when outer wing tanks are full role response is poor.


* "N was not a low altitude plane."*

Engine peaked at 15,000ft or so. Yes there were lower altitude planes but many fighters had engines that peaked in the 20,000ft foot range.
Spitfire II engine peaked 17,500ft in the summer of 1940.

edit: I made a mistake in estimating the area of wing needed per gallon of fuel, it is actually about 1/4 of a square foot. 
However the thicker part of the wing will still hold more fuel for the same amount of (or nearly) of self sealing material. More weight in the wing tips means poor roll response.

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## FLYBOYJ (May 28, 2021)

Shortround6 said:


> For some reason the US *did not *use standard temperature and pressure for these charts.



And that is why (from the charts I was working with) I was stating you can't use true air speed. The chart gave no conversion or no instructions to do so.


Shortround6 said:


> "*Wings had the SPACE to mount fuel tanks where the wing guns were mounted.* "
> 
> You would have space in two dimensions. Now the question is it was smart.


Also consider that if it was done you're looking at a stress analysis of the area and more than likely more reinforcing, unless you limit maneuvers, don't self seal the tanks and fly that fuel off first. (Thinking out loud, giving every opportunity for the old dog to succeed)


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## GregP (May 28, 2021)

The area behind the cockpit is not hard to access, but you have to pull the engine access panels to get to the engine. You might have to pull a panel above and / or below the aux-stage supercharger to get to it, but it should not require frequent service. The visibility rearward was not great. If you look straight back, you might see the carb-S/C airscoop, but the view rearward was generally not great.

For radio access, I THINK you can open up one or both of the rear canopy sides pretty easily, but will have to check that next Tuesday. I SHOULD have checked that when I took the pics. I was working on the P-63 yesterday, but I was under the belly, not on top. I was fitting a new belly panel that covers the drop tank connection. Not exactly a vital restoration task, but the devil is in the details. The airplane is coming along very nicely. I am not a regular member of the restoration crew, and was helping make new cowling internal connections (Dzus panels) for a Grumman Mallard until that P-63 panel needed to be fitted.

Cheers everyone. Have a great weekend!

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## SaparotRob (May 28, 2021)

When I read Gregp‘s (not Greg) posts, I am reminded of the Packard Automobile advertisements. 
“Ask the man who owns one.”

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## GregP (May 28, 2021)

I very definitely do NOT own a P-63. But Yanks Air Museum does. I am not a regular crew member, but get to it almost every day I am in there. They have some very interesting aircraft and items. For instance, they have a main landing gear from a Bf 110 displayed. I've never seen anything else from a real, live Bf 110, so it is interesting.

I'll ask about posting some pics and, if they say it is OK, I'll do it. If they say not to, I won't.

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## SaparotRob (May 28, 2021)

“I very definitely do NOT own a P-63.”
Close enough.

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## FLYBOYJ (May 28, 2021)

GregP said:


> The area behind the cockpit is not hard to access



Hey Greg, to clarify, area behind the cockpit behind the pilot's head. That's where radios or IFF would go


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## pbehn (May 28, 2021)

Glider said:


> There is no doubt that the P39N1 has a better performance than the Typhoon at 25,000 ft but the range of the P39N1 would be close to miserable at that altitude and the chances of a successful interception low, make that very low if your spotted when climbing up.
> In the real world if you were fighting Typhoons then at 25,000 ft you would be taking on the Spit IX and good luck with that. Even the Spitfire had a better range than any version of the P39 from late 1944 on, and no one would claim that the range of the Spitfire was it's strength.
> .


I doubt it if you apply the same principles of taking out things that weigh a lot. Take the armour cannon and IFF out of a Typhoon and how does it go? Comparing to a 1943 P-39N why not compare to a Tempest Mk V, first production aircraft flew June 21 1943.

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## FLYBOYJ (May 28, 2021)

Peter Gunn said:


> My bold/italics.
> 
> I think this sums up the P-39/63 pretty well. When I read Yeager's autobiography back in the '80's, I got the impression it was a pretty good plane to fly, but not to fight in. Although he did say that he would have happily gone to war in it if he had to. Now a guy like that would probably do alright in it but I doubt he would want to take it above 20,000 feet and fight. Who would?



Also in what environment? England? Port Moresby? Guadalcanal? Africa?

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## GregP (May 28, 2021)

Hi FBJ,

The museum P-39 has a radio there (old radio, not modern). I have never seen a P-63 with an original radio mounted there, but have also not exactly been looking for that feature, either.

A short search in Google came up with this:






Now, that LOOKS like a radio to me, but it could be a dishwasher for all I know about it. I'm betting radio, though. That is only one pic, and I didn't really see many others with an old black box in that location. If you had any rearward visibility, that would seem to take care of removing it, wouldn't it? On the plus side, you can see the rear canopy is held in with Dzus fasteners, offering access to the radio.

Incidentally, the panel I was trying to fit yesterday on the P-63 covers up the connection hole in the belly for the tank shown above. I didn't get it finished, but fitting a panel and getting the Dzus fastener holes lined up exactly is not a really fast undertaking. It is easier if you have an existing panel to copy, but we are fitting one from scratch, without any drawing. So, some good old head scratching is required.

The pic shows up in my edit window, but not when I post, so I'll try a link;

https://www.skytamer.com/1.2/2009/20090113-318.jpg

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## Shortround6 (May 28, 2021)

FLYBOYJ said:


> don't self seal the tanks and fly that fuel off first. (Thinking out loud, giving every opportunity for the old dog to succeed)



Possible, but you still have flammable fumes in the tank space unless you fit a purge system. Nitrogen, CO2 or cooled engine exhaust.

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## DerAdlerIstGelandet (May 28, 2021)

Glider said:


> Actually I (and in my opinion no one else) needs to expand on anything.
> 
> Lets sum it up
> 
> ...

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## Shortround6 (May 28, 2021)

I may have done the math wrong but I seem to get about 211hp needed to lift a 7000lb weight 5,000ft in 5 minutes. If this is anywhere near right (correction more than welcome) this would be in addition to whatever power the plane needs to maintain a certain speed at a given altitude. Or about 10.55 gallons of fuel (211 hp X 0.6 lbs per hp hour divided by 12 (for the 5 minutes) in addition to the fuel burned to cruise at level flight.

Is this wrong?


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## GregP (May 28, 2021)

From pure physics, 1 hp = 33,000 ft-lbs/ 1 min, so lifting 7,000 lbs a distance of 5,000 feet in 5 minutes should take 212.12 hp. But that would be using something like a pulley block and tackle. For airplanes, the formula above is much more that lifting a weight. But, you know that.






I went to wwiaircraftperformance.org and found a P-39 test dated 17 Jul 41. It is a P-39C (SN: 40-2988).

The test data showed 1,150 hp available from 0 - 5000 feet, and a constant rate of climb between those altitudes of 3,720 fpm. The aircraft came in at 6,689 pounds. Using a standard rate of climb formula: RC = 33,000 * ((PA - PR)/(W)), where PA = power available (hp), PR = power required for level flight (hP), W = weight (lbs), I get 3,720 fpm when the power required for level flight is equal to 395.97 hp. That leaves 754 excess horsepower to get 3,720 fpm. This takes into account for coefficient of lift, the relative efficiency of the propeller airfoil, makiing lift from forward airspeed, etc.

Formula from Aerodynamics for Naval Aviators, as I recall. This is, of course, a slightly better than first-order estimate. Still, it lets you make an estimate of rate of climb improvements with additional power. So, if we went from 1,150 hp to 1,325 hp in the same airplane at the same weight, we'd expect 4,583 fpm rate of climb. The thing is, I doubt there is much utility in a P-39C at 6,689 pounds. There isn't much fuel nor much ammunition.

Cheers, SR6!

Oh, and let me know if I missed any math in there, too. I make enough mistakes to know it can happen again!

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## P-39 Expert (May 28, 2021)

Glider said:


> Actually I (and in my opinion no one else) needs to expand on anything.
> 
> Lets sum it up
> 
> ...


Please expand above.


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## buffnut453 (May 28, 2021)

P-39 Expert said:


> *I believe the Soviets made almost exactly these changes and defeated the Luftwaffe with it.*



Of course they did...and the Yaks, LaGGs, MiGs, Lavochkins etc had nothing to do with it, right? You're also ignoring (yet again!) that the air war on the Eastern Front was fought at a much lower altitude than was the case on the Western Front.

You really need to start acknowledging what you don't know and what you don't believe if we're ever to make ANY progress in this discussion.

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## GregP (May 28, 2021)

Hi P-39 Expert. You have shown pretty good patience with the forum considering some of the posts that have been thrown at you. I have seen none of the typical internet personal attacks coming from you to us.

But, you also do not appear to be paying attention to any of the knowledge being shown to you. The moderators are being pretty patient, but I doubt things will continue to be as patient if you do not at least acknowledge some of the plain old in-your-face shortcomings of the P-39 family. It was not one of our better fighters, but it could and did thrive in a very short-range, low-altitude combat environment in Russia. Other than that narrow niche, it was not of much use to anyone and, while some South Pacific commanders welcomed it, they did so because nothing else much was available to them until Germany was beaten since Europe was the number one priority. They had to settle for what they could get. In some cases, that meant the P-39. Nobody much was happy about it, but some fighters were better than no fighters, even if they couldn't go very far or do very much due to the overwater ranges involved.

You need to let the P-39 go and just be a regular posting member of the forum. Everyone is very tired of P-39s, not just me.

Sorry if this steps on anyone else's toes.

Cheers, and I hope to be seeing you in threads OTHER than P-39 threads.

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## P-39 Expert (May 28, 2021)

Shortround6 said:


> It depends on how you want to compute the range.
> 
> The USAAF, rightly or wrongly, in their comparisons charts *did not *credit any horizontal movement in the climb to 25,000 ft cruising altitude. This was to allow for forming up and rendezvousing with the bombers. If you want to come up a figure for range/radius to compare to the planes listed in the chart then you have to use the conditions the chart says. *We are talking about the chart in the pilots manual, right? Or a different chart?*
> 
> ...


Expand above.


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## P-39 Expert (May 28, 2021)

Shortround6 said:


> "*Wings had the SPACE to mount fuel tanks where the wing guns were mounted.* "
> 
> You would have space in two dimensions. Now the question is it was smart.
> 
> ...


Expand above.


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## pbehn (May 28, 2021)

P-39 Expert said:


> *And you misspelled specializing.*


In which language? Bearing in mind the language is English.

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## DerAdlerIstGelandet (May 28, 2021)

GregP said:


> Cheers, and I hope to be seeing you in threads OTHER than P-39 threads.



And then those will become P-39 circle jerk threads...


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## GrauGeist (May 28, 2021)

pbehn said:


> In which language? Bearing in mind the language is English.


I suppose you'll have to translate everything to American English, in order for the conversation to flow without stopping for assumed grammar correction.


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## pbehn (May 28, 2021)

GrauGeist said:


> I suppose you'll have to translate everything to American English, in order for the conversation to flow without stopping for assumed grammar correction.


I had the same problem in Saudi Arabia, a computer nerd from Texas told me he couldnt understand my English, as if that is my problem not his, there were people from all over the world there and he didnt understand any of them, and that was their fault too. Many of the guys he was complaining about had English as a second or third language and some I knew could speak six.

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## P-39 Expert (May 28, 2021)

GregP said:


> Hi P-39 Expert. You have shown pretty good patience with the forum considering some of the posts that have been thrown at you. I have seen none of the typical internet personal attacks coming from you to us. *Thank you very much, I have always tried my best to be non-snarky.*
> 
> But, you also do not appear to be paying attention to any of the knowledge being shown to you. The moderators are being pretty patient, but I doubt things will continue to be as patient if you do not at least acknowledge some of the plain old in-your-face shortcomings of the P-39 family. It was not one of our better fighters, *But it and the P-40 were all that was available in 1942. *but it could and did thrive in a very short-range, low-altitude combat environment in Russia. *Only difference between combat on the eastern front and the western front was high altitude bombing by B-17/B-24 and that didn't really get going seriously until mid-'43. The 1943 P-39s were not low altitude planes and were capable of matching performance of the FW190A and Me109G up to 8000 meters and the Luftwaffe didn't care to go any higher than that. *Other than that narrow niche, it was not of much use to anyone and, while some South Pacific commanders welcomed it, they did so because nothing else much was available to them until Germany was beaten since Europe was the number one priority. They had to settle for what they could get. In some cases, that meant the P-39. Nobody much was happy about it, but some fighters were better than no fighters, even if they couldn't go very far or do very much due to the overwater ranges involved. *Again it was all that was available in 1942, along with the P-40 and F4F. 1942 was primarily a defensive war in 1942 for the AAF in the Pacific. Range was not as important then as the ability to fight at Zero/Betty altitudes. Lighter P-39s would do that.*
> 
> ...


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## DerAdlerIstGelandet (May 28, 2021)

pbehn said:


> I had the same problem in Saudi Arabia, a computer nerd from Texas told me he couldnt understand my English, as if that is my problem not his, there were people from all over the world there and he didnt understand any of them, and that was their fault too. Many of the guys he was complaining about had English as a second or third language and some I knew could speak six.



Dagumit, haven’t you lurnt American?!

Speke Merican or die!


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## GrauGeist (May 28, 2021)

I never have trouble with folks who speak "British" English or Europeans who have been schooled in proper English.
I am fluent in American English, Californian english and was tutored by a retired Oxford English professor when I was a child, because of my severe dyslexia.

So that may be why it's a non-issue for me. I would also never interrupt a conversation to point out (real or imagined grammar mistakes) - it's rude as hell.

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## Shortround6 (May 28, 2021)

There are range charts in the Back of AHT, Pages 599 and 600. 
They are the ones with bar graphs.


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## pbehn (May 28, 2021)

DerAdlerIstGelandet said:


> Dagumit, haven’t you lurnt American?!


Of course, there are very few Americans I dont understand. Same in UK if I speak in my local "argot" its hard for others to understand so I dont, My parents came from darkest Yorkshire, 45 miles away and my wife didnt understand a word when they all got together with friends. The problem with this guy Dave from Texas is he was 24 and had never been outside Texas. He really didnt believe that there were people who didnt speak English, funny to watch, like a comedy sketch and it happened every time we went into a shop.

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## pbehn (May 28, 2021)

GrauGeist said:


> I never have trouble with folks who speak "British" English or Europeans who have been schooled in proper English.
> I am fluent in American English, Californian english and was tutored by a retired Oxford English professor when I was a child, because of my severe dyslexia.
> 
> So that may be why it's a non-issue for me. I would also never interrupt a conversation to point out (real or imagined grammar mistakes) - it's rude as hell.


As an Englishman abroad you become everyones English teacher. Most of the time I wouldnt correct anyone on anything, its rude and interrups the flow of a conversation, unless they were making an error that meant they were not saying what they thought they were or were saying something offensive without knowing (it happens). Four translators I met abroad were self taught, so it want just their job but their interest and hobby. It is interesting and at times hard work figuring out how and why we say what we do, especially to Chinese and Japanese whose languages work in a completely different way.

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## FLYBOYJ (May 28, 2021)

*OK - enough!*

*It's bad enough this thread keeps going around in circles but P-39 EXPERT, you WILL start using the proper reply format to respond from here on end. Several members openly complained and it is getting cumbersome. *

*I'm willing to let the horse beating continue but please follow the forum requirement when replying! *

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## FLYBOYJ (May 28, 2021)

On Page 83, it's clearly spelled out how to do this - please follow this direction.

Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)


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## Marcel (May 28, 2021)

I thought some of you had been here long enough to know that in order to stop talking to a brick wall, you just have to stop talking. But maybe I overestimated that?

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## glennasher (May 28, 2021)

Marcel said:


> I thought some of you had been here long enough to know that in order to stop talking to a brick wall, you just have to stop talking. But maybe I overestimated that?





I believe I brought that up, maybe in those exact words, almost a year ago, now. I'm as guilty as anyone conversing with masonry, though, and I freely admit it. d:^)


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## pbehn (May 28, 2021)

DerAdlerIstGelandet said:


> Dagumit, haven’t you lurnt American?!
> 
> Speke Merican or die!


I think you may like this a German professor explaining Geordie which is from 50 miles north of myself and Rochie



and this from Yorkshire 50 miles south

 .

My grandmother used to read books in Yorkshire dialect which is English words with different meanings and German grammar. She would often say "I doubt" at the end of a sentence, which actually meant "I think" or "Ich denke".

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## Thumpalumpacus (May 28, 2021)

GrauGeist said:


> I would also never interrupt a conversation to point out (real or imagined grammar mistakes) - it's rude as hell.



I'm a writer by hobby and a lover of the language by nature. So long as I can understand what is being said or written, I don't complain about grammar or spelling, because I reckon that communication is more important than perfection.

I see such trivial corrections as a matter of someone trying to avoid a point by focusing on language instead of message.

It's not only rude, as you say -- especially on a forum where the native language of many posters is _not_ English -- it's also dissimulative, in the sense that if one makes a typo, misspelling, or grammatical error, that is alleged to impugn the point being laid.

It's lazy, cheap, and the refuge of someone who cannot answer the point.

If you know what someone means, then focusing on the correctness of how they write is dishonest.

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## Glider (May 28, 2021)

As you wish

The P39N1 operating at temperatures that were higher than normal acceptable operating levels turned in a good performance but it should be noted that this was at the cost of a very low range and without any payload. This operating at above normal temperatures is no small thing. You can get away with it for a certain period of time but sooner or later it will bite you. *P-38, P-47 and P-51 also had higher than acceptable operating temperatures. See my past post in this thread. My statement stands and applies to any performance stats posted on any aircraft of any nation. If you rely on higher than acceptable temperatures then sooner or later it will bite you*

The Typhoon another aircraft of a similar era matched the performance of the P39N1 in the early years and comfortably exceed the performance of the P39N1 from early1944 on. It should also be noted that the Typhoon carrying 2,000lb of bombs had a greater range than the P39N1 when clean and about 1,000 miles with drop tanks. *Not sure where you are getting this range figure, Typhoon had a huge engine and not a large fuel capacity. Do some research and you will soon find it. And by 1944 the P-39 should have had a two stage engine. We are in your fantasy world again. If you think something should have happened ask yourself this simple question. Why didn't it happen? *

There is no doubt that the P39N1 has a better performance than the Typhoon at 25,000 ft but the range of the P39N1 would be close to miserable at that altitude and the chances of a successful interception low, make that very low if your spotted when climbing up. *Range of a 120gal P-39N with a 110gal drop tank is about the same as a 1943 P-47 with the same drop tank. Long previous thread about that. Still, not great range but more fuel could be carried internally. *_*A fighter with a 90 gallon internal capacity relying on a 120 gallon external tank, you really think that's a good idea?*_

You can of course add additional fuel tanks but then you effectively end up with the P39Q which has a much lower performance. Y*ou know that adding fuel to the wing would mean removing the wing guns, right? About the same weight. *You can of course tweak the performance by removing the two 0.5 in the wings of the P39Q but that would make little difference to the speed. *Exactly 14mph per wwiiaircraftperformance.org. I'll take it. *Worth noting that the Me109 with 2 x 20mm underwing guns only lost 8mph when carrying them and the 0.5 was a lot smaller so the difference is likely to be no more than 4 mph. *14 mph, look at the tests. *_*I did and it's a fair point you raise. Unfortunately if you want to max out your speed at 385mph that's your choice, but I thought you preferred the 398mph of the P39N1 *_

You have a lot of fantasies about how to change the performance of the P39. New engines, removing armour, adding fuel tanks, deleting equipment with hardly any evidence (because there is next to none that exists) to back up your assertions that such changes were Easy, Obvious, Simple, Straight forward. Yet has been pointed out to you on any number of occasions, tens of thousands of flight engineers, hundreds of engineers/designers at Bell and thousands of pilots many of whom fought and died in the P39. Educated, trained and experienced people who knew every bolt, cable and rivet in the aircraft didn't make those changes. Why, because they knew it couldn't be done. Yet you, with no training or experience know better than all these people *I believe the Soviets made almost exactly these changes and defeated the Luftwaffe with it. If you could tell me where the Soviets added a two stage engine into a P39, removed armour from the nose, installed fuel tanks in the wings I and a lot of other people watching this thread would be very interested.*

I was an Artificer in the Fleet Air Arm specialising in airframes and engines. This was a training regime that took five years and I know that your statements and assumptions are puerile. I use that word deliberately because if you look up the definition, it fits. There are many others on this forum with infinitely more training and experience than myself in aviation, these are people I listen too and learn from, people who have also told you with supporting evidence that its impossible. Yet you again, know better than all of us. *All I know is what is in wwiiaircraftperformance.org, pilots manuals, Vee's for Victory, Soviet history and some hearsay from men like Chuck Yeager. And I don't know what puerile means. Again do some research on the definition it will become clear. *

No, we do not need to expand , you need to expand to give evidence to support your massive assumptions, and/or explain why you have such omnipotent knowledge on this subject.

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## pbehn (May 28, 2021)

Thumpalumpacus said:


> I'm a writer by hobby and a lover of the language by nature. So long as I can understand what is being said or written, I don't complain about grammar or spelling, because I reckon that communication is more important than perfection.
> 
> I see such trivial corrections as a matter of someone trying to avoid a point by focusing on language instead of message.
> 
> ...


It is also incorrect, which is the most important point. The world doesn't have to accept any change of spelling or grammar by anyone who is speaking someone else's language. I actually don't care about an American dictionary's spelling of an English word, because I live in England.

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## Thumpalumpacus (May 28, 2021)

pbehn said:


> It is also incorrect, which is the most important point. The world doesn't have to accept any change of spelling or grammar by anyone who is speaking someone else's language. I actually don't care about an American dictionary's spelling of an English word, because I live in England.



Again: the content is more important than the expression. Answer the point, I say, and leave the blue-pencils to the editors. This is a discussion forum, not an English classroom. I understand the Queen's English as well as American English; I lived overseas as a youth and for four years my English teacher was actually English. I really don't care either way. I'm certainly not going to pick a nit because someone makes a typo or spelling error, so long as I can understand the point they're making.

What a person means to say is more important than his expression being classroom-correct, in any dialect.

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## SaparotRob (May 28, 2021)

pbehn said:


> I think you may like this a German professor explaining Geordie which is from 50 miles north of myself and Rochie
> 
> 
> 
> ...



Very entertaining clips.


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## pbehn (May 28, 2021)

Thumpalumpacus said:


> Again: the content is more important than the expression. Answer the point, I say, and leave the blue-pencils to the editors. This is a discussion forum, not an English classroom. I understand the Queen's English as well as American English; I lived overseas as a youth and for four years my English teacher was actually English. I really don't care either way. I'm certainly not going to pick a nit because someone makes a typo or spelling error, so long as I can understand the point they're making.
> 
> What a person means to say is more important than his expression being classroom-correct, in any dialect.


I agree, but by the same token who is the final arbiter of what is correct? I just do not accept the concept of "American spelling", India has 1.4 billion people, so maybe they could decide? As I previously posted there is nothing more infuriating than being told "I dont understand your English" when you actually are English.

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## SaparotRob (May 28, 2021)

Two peoples separated by a common language.

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## SaparotRob (May 28, 2021)

And let's hear it for our friends Down Under, eh?

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## pbehn (May 28, 2021)

SaparotRob said:


> Two peoples separated by a common language.


That is only Americans, when you come to discussing Scots, the greatest moment in their lives is when an Englishman doesnt understand them when speaking their version of the language. It really does make them happy when no one understands them, as if they have invented a language just by drinking a vat of beer. I am sure 

 rochie
has had this experience.

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## SaparotRob (May 28, 2021)

The things one learns here.


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## GregP (May 28, 2021)

We can understand Yoda.

Does that count?

Away put your weapon!

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## SaparotRob (May 28, 2021)

Hand to the Almighty, the world would be a better place if we all spoke like Yoda.


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## GregP (May 28, 2021)

Be you correct, methinks.

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## Thumpalumpacus (May 28, 2021)

pbehn said:


> I agree, but by the same token who is the final arbiter of what is correct? I just do not accept the concept of "American spelling", India has 1.4 billion people, so maybe they could decide? As I previously posted there is nothing more infuriating than being told "I dont understand your English" when you actually are English.



I get what you're saying. Language, itself, evolves in a very similar manner to biological evolution, and the idea that one language or dialect is better or more proper than another is really nonsense. Different regions partake different customs and idioms, and saying one is right and the other wrong not only ignores the fluid nature of language, it is also often used to denigrate others on the basis of a silly precept.

Chauvinism in any form should be exposed, criticized, and when need be mocked.

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## pbehn (May 28, 2021)

Thumpalumpacus said:


> I get what you're saying. Language, itself, evolves in a very similar manner to biological evolution, and the idea that one language or dialect is better or more proper than another is really nonsense. Different regions partake different customs and idioms, and saying one is right and the other wrong not only ignores the fluid nature of language, it is also often used to denigrate others on the basis of a silly precept.
> 
> Chauvinism in any form should be exposed, criticized, and when need be mocked.


Oh, I don't mind him or anyone else saying they are right, I do object to them say they speak English, especially if they have never been there or actually studied the language in a university or other place. The very argument they present proves they are wrong.

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## DerAdlerIstGelandet (May 28, 2021)

Marcel said:


> I thought some of you had been here long enough to know that in order to stop talking to a brick wall, you just have to stop talking. But maybe I overestimated that?



If I were not a moderator, I would not even bother coming into this thread. No point to it.

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## pbehn (May 28, 2021)

DerAdlerIstGelandet said:


> If I were not a moderator, I would not even bother coming into this thread. No point to it.


It is "hard pounding" but that is life, when Dimlee says he learned something about the history of the P-39 and its operation then it is all worthwhile. I have learned all sorts of "stuff" but not much from the expert, who just says the same ole same ole.

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## special ed (May 28, 2021)

Re British vs American: Jail vs Gaol & curb vs Kerb. My spellcheck just went nuts.

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## Greg Boeser (May 28, 2021)

Thumpalumpacus said:


> I get what you're saying. Language, itself, evolves in a very similar manner to biological evolution, and the idea that one language or dialect is better or more proper than another is really nonsense. Different regions partake different customs and idioms, and saying one is right and the other wrong not only ignores the fluid nature of language, it is also often used to denigrate others on the basis of a silly precept.
> 
> Chauvinism in any form should be exposed, criticized, and when need be mocked.


dhjhf;dfiydudhkl;l'vxxb nmc
oufnvcaljcif n mfjbl iofkgrpnn9o!

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## pbehn (May 28, 2021)

special ed said:


> Re British vs American: Jail vs Gaol & curb vs Kerb. My spellcheck just went nuts.


That depends words meaning being permanent and cast in stone. They arent. When the Normans arrived in 1066 a dungeon was the impressive keep at the centre of a fortification, a few hundred years later a dungeon was a place where prisoners were kept with little food and water and no light. The original owners had changed the use of the building and so the use of the word. 

In another world the translation of kerbschlagbeigeversuch is Charpy test lol.


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## Thumpalumpacus (May 28, 2021)

pbehn said:


> Oh, I don't mind him or anyone else saying they are right, I do object to them say they speak English, especially if they have never been there or actually studied the language in a university or other place. The very argument they present proves they are wrong.



I've never studied English at a university, nor have I ever studied in anything at all in England.

I prefer good thinking to perfect language. The latter requires education, to be sure. The former requires an astute mind.


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## Thumpalumpacus (May 28, 2021)

Greg Boeser said:


> dhjhf;dfiydudhkl;l'vxxb nmc
> oufnvcaljcif n mfjbl iofkgrpnn9o!



I'm sensing mockery.


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## Greg Boeser (May 28, 2021)

Damn! Forgot to capitalize _dhjhf;dfiydudhkl;l'vxxb!_

Let's get back to the premise of this thread: The P-39 is the greatest warplane ever constructed. Prove me wrong!

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## Greg Boeser (May 28, 2021)

I have learned several languages, some well enough to earn money for my knowledge. I have learned that understanding a language is more than knowing which word endings to use, or the proper spelling of words. It is best to know what the other person is trying to say even when he is not saying or spelling it correctly.

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## GregP (May 28, 2021)

Ahhhh, pigeon English!

At las', Ahh unerstand.

But Ah DO speak P-39: Yes we have no fuel to speak of. Yes, we cannot fight at 25,000 feet. Wait! 7.620 metres! And, the "39" in P-39 is probably in feet, so shouldn't it be a P-7,89 instead of a P-39? Different language, huh? Might take a fortnight or so to understand it.


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## Thumpalumpacus (May 28, 2021)

Greg Boeser said:


> Damn! Forgot to capitalize _dhjhf;dfiydudhkl;l'vxxb!_
> 
> Let's get back to the premise of this thread: The P-39 is the greatest warplane ever constructed. Prove me wrong!



Bell couldn't spell Aircobra right, QED.

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## GregP (May 28, 2021)

We don't need no stinking Latin in here! QED, indeed!

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## Greg Boeser (May 28, 2021)

No, it was the British. Always throwing in those superfluous vowels. Something they picked up from their Norman conquerers I guess.

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## wuzak (May 28, 2021)

SaparotRob said:


> Hand to the Almighty, the world would be a better place if we all spoke like Yoda.



Yoda speaks in an Old English style. 

I believe many other languages still use the same sentence construction.


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## SaparotRob (May 28, 2021)

Then let's crack on with it!


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## Thumpalumpacus (May 28, 2021)

Greg Boeser said:


> No, it was the British. Always throwing in those superfluous vowels. Something they picked up from their Norman conquerers I guess.



I've complained for years -- years, mind you -- about their extraneous "u". _Colour, favour_, etc. And "aluminum" has four and not five syllables, damn it.

Gotta say I'm enjoying both Gregses posts here.

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## Greg Boeser (May 28, 2021)

I'm going to start a thread explaining why the other Bell product, The FM-1 Airacuda could have won the war all by itself if only the Brass had accepted it. 
I mean, if one 37mm cannon is good, then two is even better.

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## Shortround6 (May 28, 2021)

A short history, by me, of the armament in the P-39.

In 1936-37-38 when the project was first conceived and worked on (Requirement X-609 was issued March of 1937) the 37mm cannon was not the first choice.
A theoretical/hypothetical 25mm gun was being bandied about. The only actual 25mm automatic gun suitable for aircraft use was French and it was on the secrets list. 
The US did buy and test the 23mm Danish Madsen gun but it had a low rate of fire and an unreliable feed mechanism. The US Ordnance dept. was working on a .90 caliber gun but it was far from ready. 
Early drawings of the Bell Model 4 show a cannon with a large pan magazine on top. The 37mm was chosen as an interim weapon as it was actually "available". Captain Kelsey, headof the pursuit dept was not happy with 37mm because of the low velocity and low rate of fire. 
Available is in quotes because according to one source only 45 had been delivered by Jan of 1941 when Colt firearms shut down production to retool to allow higher production. This took about one year even with the help of some engineers for Springfield Armory. In Early 1942 demand for the 37mm outstripped supply although this was soon corrected. 

With this as a back drop the French and British decision to use the 20mm Hispano was pretty much a no-brainer. As an added complication the 37mm was on the US secrets list or at lest the "do not export" list for part of 1940 at the least. So for the French and British in 1940 it was the 20mm Hispano or nothing. 

Low production of the 37mm lead to the use of the 20mm Hispano in some US P-39Ds in addition to the ex British P-400s. 

The US P-39C used the 37mm with just a 15 round feed, in part because there were two .30 cal guns in the cowl in addition to the two .50 cal guns. 

The US .50 cal of 1936-40 was not the .50 cal of 1942 and later. It topped out at 600rpm _unsynchronized _using short belts and under no (actually 1) G load. Long belts (many planes had never actually been tested with full length belts) slowed the guns down and trying to fire while turning and pulling "G"s was also a problem, not only with rate of fire but with jams. 
The ammo was also not the same, this has been gone over in many other threads (if not this one earlier) and used slightly heavier bullets at under 2600fpm velocity. 
1940 was a year of change for the US .50 cal. At some point they boosted the rate of fire to 800rpm, still for the _unsynchronized _guns although their rate of fire should have improved. 
The US also changed the ammo, using a slightly lighter bullet and a different propellent they got the velocity up to nearly 2900fps for shorter time of flight and much improved striking power. However this was pretty much a kinetic energy weapon. The US never approved a high explosive projectile and the Incendiary round may have been scarce. The British disliked it enough to design their own. 

Which brings us to the .30 cal and .303 guns. As noted above the P-39C had two small guns in the cowl. When these were moved to the wing and another gun added in each wing the 37mm ammo was raised to 30 rounds. While the British did technically order the P-400 with wing guns they actually inherited the French version which had 7.5mm MAC 34 guns in the wings. French ammo outfit is unknown. The British were just introducing the De Wilde bullet for the .303 at the time they took over the French contract and ordered more. British were also just getting the 20mm Hispano into service so it was something of an unknown. The British didn't get any P-40s delivered to England until after the P-39 orders were placed so the American .50 cal and it's ammunition were also something of an unknown. British tests of P-40s showed a lower rate of fire for the cowl .50s than expected when they did show up. 

As far as one 37mm and two synched .50s being adequate armament goes. The US was ordering P-40Ds with four free firing wing guns and provisions for under wing 20mm cannon pods before they sighed the contract for the P-39D with the four .30 cal wing guns. 
British were in process of buying the Mustang I with four .50s (two in the cowl and one in each wing free firing) and four .303 guns. British were also ordering F4Fs with six .50 cal wing guns. How much of this was based of the 600rpm (or under) .50 cal guns I don't know. 

Some American pilots may have been very glad to have the four wing .30s because the 37mm gun in the early American planes in 1942 was notorious for jamming in just a few shots. 

another consideration for the French and British was that the 20mm Hispano only carried enough ammo for about 6 seconds of firing time, assuming the gun didn't jam first. perhaps they desired a plane that could stay in the fight longer, after the cannon ran out of ammo? 
The French were building the D 520 fighter with the 20mm gun, four 7.5mm machine guns with 675rpg (?) with a 950hp engine. The P-39 had an 1150 hp engine, adding a pair of .50 cal guns shouldn't be that big a problem?

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## buffnut453 (May 28, 2021)

GregP said:


> We can understand Yoda.
> 
> Does that count?
> 
> Away put your weapon!



That is not correct Yoda-ish. The correct sentence form is "Away your weapon put."

Sheesh....the education level of some kids today!

Alright, I'll get my coat. 😆

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## buffnut453 (May 29, 2021)

Greg Boeser said:


> dhjhf;dfiydudhkl;l'vxxb nmc
> oufnvcaljcif n mfjbl iofkgrpnn9o!



Easy for you to say!

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## Marcel (May 29, 2021)

Marcel said:


> I thought some of you had been here long enough to know that in order to stop talking to a brick wall, you just have to stop talking. But maybe I overestimated that?


Actually I didn’t mean it as a joke, I believe above is meant for both sides of the argument.

I do agree with 

 P-39 Expert
to some extent that the P-39 gets a bad rap that it doesn’t fully deserve. Actually I believe that is true for most aircraft that get a bad rap (Buffalo comes to mind). But at one point discussion makes no sense anymore. I see the discussion hardening, discussion runs around details and speculations and misinterpretations of eachother’s words. It’s just waiting until it turns ugly and personal and the mod team will have to step in to close threads and put some people on pauze time for a while. Sometimes you should just give it a rest, enjoy some polite discussions about other topics for some time.

And again, this is not solely aimed at 

 P-39 Expert
, but it’s meant for all of the participants of this circus.

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## ThomasP (May 29, 2021)

Hey GregP,

When you check the radio access on the P-39, I believe that you will find that the right side of the rear canopy is (was originally) hinged for easier access to the radio. I ran across this bit of info in one or another P-39 manual a number of years ago, unfortunately I do not remember which one.  I think it was a maintenance manual, but am not sure.


re the P-39C climb rate:

Unless I am missing something, you did not factor the propeller efficiency (e) into your calculations. This factor is not included in the basic formula you are using. I usually use an e of .83 unless I have specific data on the propeller used.

Your PR value of 395.97 at Vclimb seems high to me. I get about 300-336 BHPe (depending on what drag factor I use) up to ROCmax critical altitude. I could be off on this. I used the low end of 300 BHPe for the P-39C since it was relatively light and clean for the tests.

If you remember the other discussion (up-thread) where the issue of the P-39C claimed ROC came up, I could not get it past about 3270 ft/min on the 1160 BHP listed in the test, without using the equivalent of early-war WEP ratings (1320 BHP) or by using a zoom climb. In order to get the claimed sustained ROC (3720 ft/min) we would need a value of 1 for e, which is not possible (obviously). The best WWII era value for e (at climbing speeds) that I have run across is somewhere around .85 (this was a Rotol 3- and 4-blade prop with Jablo blades, wide at the base, like those fitted to many Hurricanes and Spitfires/Seafires). There may be other props that attained this value but I have not run across any actual data that says so, at least not that saw service in WWII. Maybe some of the German wide blade types? Or the late-war US paddle types? As far as I am aware, the best e value for a conventional airplane prop of today's era is .91 (a 2-blade made by Hartzell).

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## P-39 Expert (May 29, 2021)

Shortround6 said:


> A short history, by me, of the armament in the P-39.
> 
> In 1936-37-38 when the project was first conceived and worked on (Requirement X-609 was issued March of 1937) the 37mm cannon was not the first choice.
> A theoretical/hypothetical 25mm gun was being bandied about. The only actual 25mm automatic gun suitable for aircraft use was French and it was on the secrets list.
> ...


As usual, a very informative, factual and well researched post. However I might disagree with your definition of "short". Just kidding.

Regarding the 30calMGs, AHT says their effective range was only 200 yards. Is that due to trajectory drop? 

Regarding the 37mm cannon, supposedly the jamming problem was corrected with the P-39L model with the heating air exit louvers in the forward gun bay that allowed better flow of heated air from the cockpit that kept the cannon from freezing at altitude. Ideally in hindsight the 20mm cannon should have been used on all models prior to the L. The 20mm was used in over 1000 P-400s and P-39D-1s. I always thought the 20mm cannon with 120-150 rounds would have been the ideal solution. Seems doable since the P-38F had a 150 round belt fed magazine in production from March 1942. Just my opinion.


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## P-39 Expert (May 29, 2021)

Thumpalumpacus said:


> Just put "


" at the end of the part you want to reference, and delete the rest. Or separate it into another paragraph. If you want to learn that we can take it to PM, it's easy but there's no sense in interrupting the flogging of a deceased equine.[/QUOTE]
Please PM me, I didn't realize my replies were a problem. Not sure when to use "quote" or "reply". Thanks in advance for your help.


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## Thumpalumpacus (May 29, 2021)

P-39 Expert said:


> Please PM me, I didn't realize my replies were a problem. Not sure when to use "quote" or "reply". Thanks in advance for your help.



Sent


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## special ed (May 29, 2021)

Wasn't the QED a racer in the 1930s? Just asking.


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## special ed (May 29, 2021)

Don't the French put a lot of extra consonants at the end of words because they have them left over and then make them silent to add to the confusion?

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## Dimlee (May 29, 2021)

pbehn said:


> I think you may like this a German professor explaining Geordie which is from 50 miles north of myself and Rochie
> 
> 
> 
> ...




I remember my first voyage to USA in early 1990s. Two pilots boarded in Chesapeake Bay. They spoke to me and my helmsman in "normal" English. One of them picked up his walkie talkie and gave orders in...well... "less English" (for my Russian ears). And then they talked to each other in some alien language and I was ready to burst into tears.
One year later I served on a small tanker which visited many ports in UK along the coast and in the Manchester Canal. That was another eye (ear?) opening experience. Pubs were the best language schools. A pint or two made the learning curve smoother.

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## GregP (May 29, 2021)

Hi ThomasP,

The formula I used came from an aerodynamics text, but it only seems prudent to account for propeller efficiency. But the efficiency is already there when you check your rate of climb to start with. The intent of the formula was to predict the rate of climb with a change in horsepower assuming an engine tweak, not if the propeller changed or the aircraft got heavier.

Basically, you check your rate of climb and calculate your horsepower from the engine manual. Next, solve for the power required for level flight. Then, you vary the horsepower to get the new ROC. 

But, your version of it seems reasonable. To check, I'd have to go try in a real airplane at different horsepower settings and verify the ROC. Unfortunately, I am not current in my license and am not likely to get current soon. But, I will see what I can do.

Cheers!


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## rochie (May 29, 2021)

pbehn said:


> I think you may like this a German professor explaining Geordie which is from 50 miles north of myself and Rochie
> 
> 
> 
> ...



Terry (Airfrmes ) and I once spent an afternoon spamming a thread on here by typing in Geordie.
one of our American cousins's head popped when he read it

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## Airframes (May 29, 2021)

Wheyaye man, ana think we shud gan an doit again like marra !
Howay, let's coin the corner an tappylappy doon the boozer an warkit oot bonny lad !


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## buffnut453 (May 29, 2021)

Why can't the English teach their children how to speak?


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## GrauGeist (May 29, 2021)

buffnut453 said:


> Why can't the English teach their children how to speak?



And drive on the correct side of the road, too.

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## rochie (May 29, 2021)

Airframes said:


> Wheyaye man, ana think we shud gan an doit again like marra !
> Howay, let's coin the corner an tappylappy doon the boozer an warkit oot bonny lad !


aye soonds canny like marra but divent narr if wu gunna mek it like !


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## pbehn (May 29, 2021)

GrauGeist said:


> And drive on the correct side of the road, too.


We drive on the left to avoid all the idiots who drive on the right.

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## rochie (May 29, 2021)

GrauGeist said:


> And drive on the correct side of the road, too.


Hey, Hey we'll have none of that old fruit !


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## buffnut453 (May 29, 2021)

GrauGeist said:


> And drive on the correct side of the road, too.



They do...America copied the French. 'Nuff said! 

Actually, driving on the left makes perfect sense because it ensures the right arm is free to wield a weapon if the person coming the other way demonstrates hostile intent. Unfortunately, since the advent of the automobile, that feature has become less significant...which probably accounts for the downfall of the British Empire.

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## GrauGeist (May 29, 2021)

buffnut453 said:


> They do...America copied the French. 'Nuff said!
> 
> Actually, driving on the left makes perfect sense because it ensures the right arm is free to wield a weapon if the person coming the other way demonstrates hostile intent. Unfortunately, since the advent of the automobile, that feature has become less significant...which probably accounts for the downfall of the British Empire.


But I disagree!
You'll note that in Jousting tournaments, the contestants ride to the right of the rail opposing each other in order to present their lance to the opponent.

The driver conveniently being on the left side of the vehicle, on the right-hand of the road reflects this noble tradition

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## pbehn (May 29, 2021)

GrauGeist said:


> But I disagree!
> You'll note that in Jousting tournaments, the contestants ride to the right of the rail opposing each other in order to present their lance to the opponent.
> 
> The driver conveniently being on the left side of the vehicle, on the right-hand of the road reflects this noble tradition


Is that a real one you went to eight hundred years ago, or one you saw on TV?

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## buffnut453 (May 29, 2021)

GrauGeist said:


> But I disagree!



What a surprise!!!!



GrauGeist said:


> You'll note that in Jousting tournaments, the contestants ride to the right of the rail opposing each other in order to present their lance to the opponent.
> 
> The driver conveniently being on the left side of the vehicle, on the right-hand of the road reflects this noble tradition



You're stretching there, my friend. Jousting had formal rules and was a competition. It wasn't a substitute for travelling along country lanes where a dastardly highwayman could really ruin one's day. 

As to the relevance of competitions to general driving behaviours, in NASCAR the drivers only make left turns....so is that relevant to the highway?


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## Marcel (May 29, 2021)

buffnut453 said:


> You're stretching there, my friend. Jousting had formal rules and was a competition. It wasn't a substitute for travelling along country lanes where a dastardly highwayman could really ruin one's day.
> As to the relevance of competitions to general driving behaviours, in NASCAR the drivers only make left turns....so is that relevant to the highway?


You clearly havn't been to America. The highways make *no* turns at all there

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## Milosh (May 29, 2021)

buffnut453 said:


> As to the relevance of competitions to general driving behaviours, *in NASCAR the drivers only make left turns*


There are some tracks where they turn right and left.

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## buffnut453 (May 29, 2021)

Milosh said:


> There are some tracks where they turn right and left.



Wow!!! Progress!!!!! 😃


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## special ed (May 29, 2021)

The Germans drive on the right and it is a competition.


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## Glider (May 29, 2021)

Dimlee said:


> I remember my first voyage to USA in early 1990s. Two pilots boarded in Chesapeake Bay. They spoke to me and my helmsman in "normal" English. One of them picked up his walkie talkie and gave orders in...well... "less English" (for my Russian ears). And then they talked to each other in some alien language and I was ready to burst into tears.
> One year later I served on a small tanker which visited many ports in UK along the coast and in the Manchester Canal. That was another eye (ear?) opening experience. Pubs were the best language schools. A pint or two made the learning curve smoother.


When I joined the navy one of the class had a very strong Geordie accent. It was so bad he was given elocution lessons because as the PO said 'people need to understand you in a full gale' which makes a lot of sense.

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## buffnut453 (May 29, 2021)

special ed said:


> The Germans drive on the right and it is a competition.



Well, they have to so they can invade France more effectively. 😃

And, yes, I'll get my coat.....AGAIN!!!

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## rochie (May 29, 2021)

My grandad was from Sunderland and had a very strong accent, so much i struggled to understand him !


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## pbehn (May 29, 2021)

Dimlee said:


> I remember my first voyage to USA in early 1990s. Two pilots boarded in Chesapeake Bay. They spoke to me and my helmsman in "normal" English. One of them picked up his walkie talkie and gave orders in...well... "less English" (for my Russian ears). And then they talked to each other in some alien language and I was ready to burst into tears.
> One year later I served on a small tanker which visited many ports in UK along the coast and in the Manchester Canal. That was another eye (ear?) opening experience. Pubs were the best language schools. A pint or two made the learning curve smoother.


On the other side of the coin, driving across Saudi Arabia in a gas guzzling V8 van that needed filling up every 100-120 miles I was running out of fuel around Riyadh. Diverted off the main highway because of roadworks in a panic I pulled into an obviously disused petrol station. It had "ESSO" above it but all the pumps were gone and the whole place was derelict. Enjoying the evening sun was an old guy in a rocking chair. I said "Excuse me, do you speak English". He said "Of course old boy (I was 28), what is the problem" in perfect Oxford English. The guy had a degree in English FROM Oxford university, how he came to be sat in the sun in a wrecked petrol station in Saudi I have no idea. Anyway, he told me where I could get petrol and thats all that mattered at the time.

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## GregP (May 29, 2021)

He didn't offer you tea and crumpets?

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## Thumpalumpacus (May 29, 2021)

pbehn said:


> On the other side of the coin, driving across Saudi Arabia in a gas guzzling V8 van that needed filling up every 100-120 miles I was running out of fuel around Riyadh. Diverted off the main highway because of roadworks in a panic I pulled into an obviously disused petrol station. It had "ESSO" above it but all the pumps were gone and the whole place was derelict. Enjoying the evening sun was an old guy in a rocking chair. I said "Excuse me, do you speak English". He said "Of course old boy (I was 28), what is the problem" in perfect Oxford English. The guy had a degree in English FROM Oxford university, how he came to be sat in the sun in a wrecked petrol station in Saudi I have no idea. Anyway, he told me where I could get petrol and thats all that mattered at the time.



You and I are members of one club, at least: _Those who've driven in Saudi and lived to tell the tale._

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## pbehn (May 29, 2021)

GregP said:


> He didn't offer you tea and crumpets?


No but if his wife was there she may have. In the Salzgitter-Mannessman-Vallourec Vorschung (centre for German metallurgical research) in Duisberg, the boss was a completely bilingual female. When she was hectoring her employees in German she looked and sounded like a throwback to the Nazi era, when she spoke to me in English (I never let on I spoke German) she looked and sounded like a vicars wife at a tea party. It really was remarkable to see, not only the language but the mannerisms, her father was British Army and her mother was German landed gentry I found out in my time there. Edit I used to drive there from Rouen every second Friday for months to witness mechanical tests because the test house was "computerised" on the first day they made the biggest ff up I saw in my career.

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## Milosh (May 29, 2021)

buffnut453 said:


> Wow!!! Progress!!!!! 😃


Yah from the '60s. There was some great races at Riverside.


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## BiffF15 (May 29, 2021)

Thumpalumpacus said:


> You and I are members of one club, at least: _Those who've driven in Saudi and lived to tell the tale._



That makes three of us. First time was August 1990. They drive like f--k. We would be driving along and smell dead animal (really strong). We learned to floor it until you got past the wreck (camel walks in front of speeding vehicle, crash ensues, all is pushed to the side of the road and left to rot/rust/decompose). Spent a week in Riyadh in 94 working in the RSAF HQ. They would pass in the breakdown lane. We called it the Allah Lane, as only he protected you when using it. It was interesting to see to 12 year olds driving a car by themselves as well. The things that go on over there are not fit to be published.

Cheers,
Biff


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## special ed (May 29, 2021)

I took four years of Spanish in high school and Mr. Martinez taught proper Castillian and told us of the various dialects from country to country. The only Spanish speaking people I have been able to converse with are those students who also took four years in high school, a very proper older lady who spoke to me in Spanish in a Spanish restaurant while I was explaining the menu to those with me. The only other time I completely understood, was a man scolding his son about his new shoes. The man turned out to be the Spanish Consul to New Orleans. Where my Spanish got me in trouble was in Russian class in the Air Force. The classroom rule was when we entered the room, only Russian could be spoken and during conversation with the instructor the guys would break out laughing. It turns out whenever I didn't know the Russian word, I would use the Spanish word. I have great respect for those who speak several languages.

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## Thumpalumpacus (May 29, 2021)

BiffF15 said:


> That makes three of us. First time was August 1990. They drive like f--k. We would be driving along and smell dead animal (really strong). We learned to floor it until you got past the wreck (camel walks in front of speeding vehicle, crash ensues, all is pushed to the side of the road and left to rot/rust/decompose). Spent a week in Riyadh in 94 working in the RSAF HQ. They would pass in the breakdown lane. We called it the Allah Lane, as only he protected you when using it. It was interesting to see to 12 year olds driving a car by themselves as well. The things that go on over there are not fit to be published.
> 
> Cheers,
> Biff



Yeah, "Allah's Lane" was a thing with us too -- I was there from Mar-Jul 92.

As firefighters we had been trained to pull over and render assistance to any emergency we saw in progress, on- or off-duty. But when we hit Riyadh, our indoc specifically stated that under no circumstances were we to do that, because, well, _inshallah_. Allegedly they gave Allah 30 minutes to decide, and who were we to mess with that?

I can't speak to whether or not that was true, or simple USAF misreading, or what. What I do know is that after driving the Circle of Death on the south side of the city, coming from Eskan Village where we were quartered, I felt like I could fly a brick through a hurricane. I look at these jerks in downtown Austin and think "you ain't got nothin' on me, pal," lol.

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## BiffF15 (May 29, 2021)

Thumpalumpacus said:


> Yeah, "Allah's Lane" was a thing with us too -- I was there from Mar-Jul 92.
> 
> As firefighters we had been trained to pull over and render assistance to any emergency we saw in progress, on- or off-duty. But when we hit Riyadh, our indoc specifically stated that under no circumstances were we to do that, because, well, _inshallah_. Allegedly they gave Allah 30 minutes to decide, and who were we to mess with that?
> 
> I can't speak to whether or not that was true, or simple USAF misreading, or what. What I do know is that after driving the Circle of Death on the south side of the city, coming from Eskan Village where we were quartered, I felt like I could fly a brick through a hurricane. I look at these jerks in downtown Austin and think "you ain't got nothin' on me, pal," lol.



I lived with a bunch of USN NFO/WSO types while down there. We would leave to/from Eskan as a two ship, and pre-brief the Circle of Death as you call it. Someone would trap a guy on the inside of the round about, and the second car would support. After two or three laps I'm surprised the guy didn't have a coronary. Lots of unique hand gestures would be passed. The trapee never suspected two cars working tandem tactics. Yes, sometimes it's interesting to be the ugly American. Hats off to the Brits, as their roads were first class.

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## pbehn (May 29, 2021)

Thumpalumpacus said:


> You and I are members of one club, at least: _Those who've driven in Saudi and lived to tell the tale._


My daily "jaunt" in 1985-86 was on the old Abqaiq road. I turned off after a electricity station and drove across the desert for a few miles to the pipe mill. When it was dark you had Saudis driving on the wrong side of the road with no lights, they switched their lights on at the last second to scare the foreigners, sometimes they were a little late with the lights and added to the Abqaiq roads incredible statistics. Times have changed at the time road accidents were killing young male Saudis faster than they were being born.

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## Thumpalumpacus (May 29, 2021)

pbehn said:


> My daily "jaunt" in 1985-86 was on the old Abqaiq road. I turned off after a electricity station and drove across the desert for a few miles to the pipe mill. When it was dark you had Saudis driving on the wrong side of the road with no lights, they switched their lights on at the last second to scare the foreigners, sometimes they were a little late with the lights and added to the Abqaiq roads incredible statistics. Times have changed at the time road accidents were killing young male Saudis faster than they were being born.



I don't know that I've driven that particular road, but I recognize the behaviors you describe.

I never drove in the dark over there, we only went into town during the day. But yeah, wreckage alongside the road was a regular thing.


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## Thumpalumpacus (May 29, 2021)

BiffF15 said:


> I lived with a bunch of USN NFO/WSO types while down there. We would leave to/from Eskan as a two ship, and pre-brief the Circle of Death as you call it. Someone would trap a guy on the inside of the round about, and the second car would support. After two or three laps I'm surprised the guy didn't have a coronary. Lots of unique hand gestures would be passed. The trapee never suspected two cars working tandem tactics. Yes, sometimes it's interesting to be the ugly American. Hats off to the Brits, as their roads were first class.



lol, "thumbs up" from a Middle-Eastern driver ain't a compliment!


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## BiffF15 (May 29, 2021)

Thumpalumpacus said:


> lol, "thumbs up" from a Middle-Eastern driver ain't a compliment!



Nor were the middle three fingers thrust upright with a twist... Those Navy guys were entertaining.

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## Thumpalumpacus (May 29, 2021)

BiffF15 said:


> Nor were the middle three fingers thrust upright with a twist... Those Navy guys were entertaining.



Left wrist in the crook of the right elbow -- with a raised right fist -- was understood by both sides, but doing it while driving could be tricky.

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## pbehn (May 29, 2021)

BiffF15 said:


> Nor were the middle three fingers thrust upright with a twist... Those Navy guys were entertaining.


Hey Biff, things have improved a lot since we left as you can see here. You really cant explain what it is like there Report: Saudi Arabia records 526,000 road accidents annually

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## Ascent (May 30, 2021)

rochie said:


> My grandad was from Sunderland and had a very strong accent, so much i struggled to understand him !


Mine was from South Shields and my generation was the first not to be born on Tyneside for a couple hundred years.

I've never driven in Saudi but by the sound of things it's very similar to Kuwait where I had a few operational detatchments supporting the southern no fly zone in Iraq. You counted the wreck bythe side of the road as you headed into Kuwait City on a down day.

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## P-39 Expert (May 30, 2021)

Please don't blame me for the length of this thread.

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## Marcel (May 30, 2021)

P-39 Expert said:


> Please don't blame me for the length of this thread.


I don’t


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## glennasher (May 30, 2021)

P-39 Expert said:


> Please don't blame me for the length of this thread.





"Please expand above".

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## GregP (May 30, 2021)

Only the first 80 pages ... but, hey, what's a keyboard for?

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## Glider (May 30, 2021)

buffnut453 said:


> Well, they have to so they can invade France more effectively. 😃
> 
> And, yes, I'll get my coat.....AGAIN!!!


How many coats have you got!!

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## buffnut453 (May 30, 2021)

Glider said:


> How many coats have you got!!



As many as I need! And if that's not enough, I'll steal yours.

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## GregP (May 30, 2021)

Fire the retro commode rocket!


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## Thumpalumpacus (May 30, 2021)

GregP said:


> Fire the retro commode rocket!



Greg, that is just an obnoxious thought. 

No doubt you're proud; I would be too.


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## GregP (May 30, 2021)

Just a poor attempt at some humor, likely a result of tired-of-pandemic and too many P-39s, nothing directed at you.

Cheers, Thumpalumpacus.

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## Thumpalumpacus (May 31, 2021)

GregP said:


> Just a poor attempt at some humor, likely a result of tired-of-pandemic and too many P-39s, nothing directed at you.
> 
> Cheers, Thumpalumpacus.



Sorry I wasn't clear -- but my comment was made only in jest, bud.

But a retro-commode rocket ... ouch!


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## GregP (May 31, 2021)

It's when you know you're in the crap! 

You know, in a cloud, compass is spinning and the airspeed is low ... and then you see a P-39!

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## DerAdlerIstGelandet (Jun 3, 2021)

Here is the elusive high altitude P-39

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## SaparotRob (Jun 3, 2021)

It's like we can't stop ourselves!

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## P-39 Expert (Jun 4, 2021)

DerAdlerIstGelandet said:


> Here is the elusive high altitude P-39
> 
> View attachment 625973


Actually that's the stealth P-39.

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## vikingBerserker (Jun 4, 2021)

HEY, you need to post that pic on Roadking's color thread!

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## gordonm1 (Jun 4, 2021)

DerAdlerIstGelandet said:


> Here is the elusive high altitude P-39
> 
> I used to make those high altitude P-39's fly off rocks with my .270. Getting old and soft now.

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## DerAdlerIstGelandet (Jun 25, 2021)

P-39 Expert


This is your thread for P-39 discussion. There is no need to repost over and over the same stuff from this thread in other threads not even about the P-39. Please comply.

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## P-39 Expert (Jun 25, 2021)

DerAdlerIstGelandet said:


> P-39 Expert
> 
> 
> This is your thread for P-39 discussion. There is no need to repost over and over the same stuff from this thread in other threads not even about the P-39. Please comply.


Thank you. I'll post here from now on.


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## 33k in the air (Jun 26, 2021)

DerAdlerIstGelandet said:


> Here is the elusive high altitude P-39
> 
> View attachment 625973



Is it behind the rodent?


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## DerAdlerIstGelandet (Jun 26, 2021)

33k in the air said:


> Is it behind the rodent?



Read the thread and it will make sense...


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## P-39 Expert (Jun 26, 2021)

Admin/mods have graciously allowed me to post P-39 information in this thread to keep from cluttering/hijacking other threads. This seems very fair to me since each of my posts on the other threads usually generate about 10 replies ranging from angry rebuttals to ridicule to pictures of rodents which does indeed clutter/hijack the other threads. Hopefully the angry rebuttals, ridicule and rodent photos will be confined to this thread only.

Any P-39 discussion is welcome here. No matter if you believe the P-39 was a useful fighter or it was useless junk that tumbled during every turn and the engine quit at 12000'.

Before being banished to this thread I had posted a chart of the P-39K from wwiiaircraftperformance.org that reflected the performance of the Merlin P-40F superimposed in blue. It is posted here again to show that a Merlin P-40F had about the same performance as a standard P-39K (an early version with the lower rated Allison V-1710-63 with a critical altitude of 12000'). 

Again all your comments are welcome. Including rodent photos if you feel them necessary. Thanks.

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## nuuumannn (Jun 26, 2021)

Thumpalumpacus said:


> And "aluminum" has four and not five syllables, damn it.



A wee bit of thread drift, the US spelling is in fact the original spelling of the word. It was initially written by an Englishman as _aluminum_, but it was changed to alumin_ium_, again by the English sometime later to fit with other elements in the periodic table, such as uranium, sodium etc...

As you were, Pee Thirtyniners...

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## pbehn (Jun 26, 2021)

P-39 Expert said:


> Admin/mods have graciously allowed me to post P-39 information in this thread to keep from cluttering/hijacking other threads. This seems very fair to me since each of my posts on the other threads usually generate about 10 replies ranging from angry rebuttals to ridicule to pictures of rodents which does indeed clutter/hijack the other threads. Hopefully the angry rebuttals, ridicule and rodent photos will be confined to this thread only.
> 
> Any P-39 discussion is welcome here. No matter if you believe the P-39 was a useful fighter or it was useless junk that tumbled during every turn and the engine quit at 12000'.
> 
> ...


It isnt as if we havnt covered this before, the question is when? The P-39s that were first sent to UK did much more than you describe. Compasses didnt work, the cabin filled with smoke when guns fired, they overheated and the landing gear broke, as you know. So when was the first P-39K in squadron service? The Mustang Mk I, Spitfire MkIX were introduced in early 1942 and the P-47 in late 1942/early 1943. The P-39 was what it was, it was behind the curve, it didnt start to arrive in UK until after the P-40 was in service there and N Africa.


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## Thumpalumpacus (Jun 26, 2021)

nuuumannn said:


> A wee bit of thread drift, the US spelling is in fact the original spelling of the word. It was initially written by an Englishman as _aluminum_, but it was changed to alumin_ium_, again by the English sometime later to fit with other elements in the periodic table, such as uranium, sodium etc...
> 
> As you were, Pee Thirtyniners...



I had no idea.


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## SaparotRob (Jun 26, 2021)

Was there ever a match up with a P-39 vs. a B-239 during the Continuation War?


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## Glider (Jun 26, 2021)

SaparotRob said:


> Was there ever a match up with a P-39 vs. a B-239 during the Continuation War?


Now there's a thought


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## buffnut453 (Jun 26, 2021)

I took a quick at the list of victories in Suomen Ilmavoimien Historia 1b "Brewster Model 239 osa 2" by Kalevi Keskinen and Kari Stenman. It lists 2 kills against Airacobras on 17 June 1944 and 29 July 1944. The latter was the third-last victory by Brewsters.

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## Snautzer01 (Jun 26, 2021)

P-39 Expert said:


> Admin/mods have graciously allowed me to post P-39 information in this thread to keep from cluttering/hijacking other threads. This seems very fair to me since each of my posts on the other threads usually generate about 10 replies ranging from angry rebuttals to ridicule to pictures of rodents which does indeed clutter/hijack the other threads. Hopefully the angry rebuttals, ridicule and rodent photos will be confined to this thread only.
> 
> Any P-39 discussion is welcome here. No matter if you believe the P-39 was a useful fighter or it was useless junk that tumbled during every turn and the engine quit at 12000'.
> 
> ...


Although some times made fun of, or some pictures of rodent were placed, it is a noteworthy you created one of the most active threads here. In the end all of us will know a lot more of facts about this plane. I learned things about the p-39. And i like the darn thing.
So keep at it. Be the champion for it. Right or wrong, its all about learning and you do seem to know how to get the fellows to the books.

Regards

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## 33k in the air (Jun 26, 2021)

DerAdlerIstGelandet said:


> Read the thread and it will make sense...



You're supposed to reply,

"No, it IS the rodent!"

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## SaparotRob (Jun 26, 2021)

Snautzer01 said:


> Although some times made fun of, or some pictures of rodent were placed, it is a noteworthy you created one of the most active threads here. In the end all of us will know a lot more of facts about this plane. I learned things about the p-39. And i like the darn thing.
> So keep at it. Be the champion for it. Right or wrong, its all about learning and you do seem to know how to get the fellows to the books.
> 
> Regards


Best running joke, EVER!

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## buffnut453 (Jun 26, 2021)

SaparotRob said:


> Best running joke, EVER!









I AGREE!!!!

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## SaparotRob (Jun 26, 2021)

Seriously, I agree with with Snautzer01. I read through most of the thread and I picked up A LOT on aeronautics, especially about my favorite planes. Didn't bother with any of the formulae. I'll let SR6 check the math. I have a feeling that more of us enjoy the thread than will admit.

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## DerAdlerIstGelandet (Jun 26, 2021)

It has been interesting. We just don’t need the same discussion in every thread...

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## P-39 Expert (Jun 26, 2021)

pbehn said:


> It isnt as if we havnt covered this before, the question is when? The P-39s that were first sent to UK did much more than you describe. Compasses didnt work, the cabin filled with smoke when guns fired, they overheated and the landing gear broke, as you know. So when was the first P-39K in squadron service? The Mustang Mk I, Spitfire MkIX were introduced in early 1942 and the P-47 in late 1942/early 1943. The P-39 was what it was, it was behind the curve, it didnt start to arrive in UK until after the P-40 was in service there and N Africa.


The first P-39s (P-400) sent to the UK were literally some of the first P-39s manufactured, there were some bugs as with any new plane. The problems you mention were soon worked out. The P-39K/L were produced July/September 1942 and were on Guadalcanal by September. P-400s were there from the beginning (August 1942) albeit they were those with the British oxygen system which was incompatible with the Marine equipment on Guadalcanal, so their altitude was limited to 12000'. The P-39/400 was there for combat from the beginning of the war. Over 700 had been produced by Pearl Harbor and almost 3000 were produced by the end of 1942. 

I believe you are a little off on combat introduction of the Spitfire IX Spitfire Mk IX versus Me 109 G - Flight Testing The first squadron was introduced at the end of July and initially only 4 squadrons were in combat. Series Mark IX production began in early 1943 with the introduction of the Merlin 63, 66 and 70. The initial P-47 combat mission was on April 30, 1943 coinciding with the 8thAFs first 100 plane raid. The Mustang Mk I first combat was in May '42 and only 138 had been produced in 1941. The 100 units per month mark was not achieved until April 1943.

The P-39, P-40 and F4F were the only US planes available through almost all the first year of the war. The P-39 and P-40 were the most numerous AAF fighters in the Pacific until September 1943. The P-38 saw combat in late '42, the Corsair in February '43, the P-47 in late April '43, the Hellcat in August and the Merlin Mustang in late '43.


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## P-39 Expert (Jun 26, 2021)

Snautzer01 said:


> Although some times made fun of, or some pictures of rodent were placed, it is a noteworthy you created one of the most active threads here. In the end all of us will know a lot more of facts about this plane. I learned things about the p-39. And i like the darn thing.
> So keep at it. Be the champion for it. Right or wrong, its all about learning and you do seem to know how to get the fellows to the books.
> 
> Regards


That's the point I am trying to make. A lot (most) P-39 information was incorrect according to wwiiaircraftperformance.org. The P-39 information there (official performance tests) was not released publicly until September 2012. This was before the William Green/Gordon Swanborough and AHT reference books came out. Most of their performance data on the P-39 is wrong. Remember for decades the P-39 in Soviet service was known as a tank buster? We know now that it was one of their primary air defense fighters, not a ground attack plane.


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## pbehn (Jun 26, 2021)

P-39 Expert said:


> The first P-39s (P-400) sent to the UK were literally some of the first P-39s manufactured, there were some bugs as with any new plane. The problems you mention were soon worked out. The P-39K/L were produced July/September 1942 and were on Guadalcanal by September. P-400s were there from the beginning (August 1942) albeit they were those with the British oxygen system which was incompatible with the Marine equipment on Guadalcanal, so their altitude was limited to 12000'. The P-39/400 was there for combat from the beginning of the war. Over 700 had been produced by Pearl Harbor and almost 3000 were produced by the end of 1942.
> 
> I believe you are a little off on combat introduction of the Spitfire IX Spitfire Mk IX versus Me 109 G - Flight Testing The first squadron was introduced at the end of July and initially only 4 squadrons were in combat. Series Mark IX production began in early 1943 with the introduction of the Merlin 63, 66 and 70. The initial P-47 combat mission was on April 30, 1943 coinciding with the 8thAFs first 100 plane raid. The Mustang Mk I first combat was in May '42 and only 138 had been produced in 1941. The 100 units per month mark was not achieved until April 1943.
> 
> The P-39, P-40 and F4F were the only US planes available through almost all the first year of the war. The P-39 and P-40 were the most numerous AAF fighters in the Pacific until September 1943. The P-38 saw combat in late '42, the Corsair in February '43, the P-47 in late April '43, the Hellcat in August and the Merlin Mustang in late '43.


There were more than a few bugs, they were grounded after being issued for service and only 4 aircraft ever were used in operations in UK "Only one RAF squadron ever received the Airacobra. No.601 “City of London” Squadron swapped its Hurricane IICs for Airacobras in August 1941, just in time to see the aircraft withdrawn to have twenty-five modifications made to the fuselage. The first four aircraft were finally declared operational in October 1941." There is a difference between production, arrival in UK, issued to squadrons, and being used on operations/in combat. The same difference applies to all aircraft. Six squadrons of Spitfire Mk IX and a similar number of Mustang Mk Is were used at Dieppe, just 10 months after the only missions P-39s performed in UK. As an operational, sorted type the three were contemporaries of each other. For British forces the P-40 and F4F had far more utility and were there first, as sorted aircraft.

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## P-39 Expert (Jun 26, 2021)

pbehn said:


> There were more than a few bugs, they were grounded after being issued for service and only 4 aircraft ever were used in operations in UK "Only one RAF squadron ever received the Airacobra. No.601 “City of London” Squadron swapped its Hurricane IICs for Airacobras in August 1941, just in time to see the aircraft withdrawn to have twenty-five modifications made to the fuselage. The first four aircraft were finally declared operational in October 1941." There is a difference between production, arrival in UK, issued to squadrons, and being used on operations/in combat. The same difference applies to all aircraft. Six squadrons of Spitfire Mk IX and a similar number of Mustang Mk Is were used at Dieppe, just 10 months after the only missions P-39s performed in UK. As an operational, sorted type the three were contemporaries of each other. For British forces the P-40 and F4F had far more utility and were there first, as sorted aircraft.


The bugs were worked out in time for AAF service in 1942. Brand new production models all had numerous bugs to work out. The British didn't want those planes anyway. The Battle of Britain was past and they had adequate production of internal fighters to meet their needs. They did the same thing with P-38s ordered as Lightning II. They ordered them in wierd configurations (no turbochargers, no handed propellers) and refused to pay for them when production began after the BoB was over. They no longer needed them. Personally I believe that both the P-400 and Lightning II were ordered as ground attack planes. The P-400 was vastly overweight (excessive armor plate and .30cal wing guns) and the Lightning II had no turbochargers.


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## pbehn (Jun 26, 2021)

P-39 Expert said:


> The bugs were worked out in time for AAF service in 1942. Brand new production models all had numerous bugs to work out. The British didn't want those planes anyway. The Battle of Britain was past and they had adequate production of internal fighters to meet their needs. They did the same thing with P-38s ordered as Lightning II. They ordered them in wierd configurations (no turbochargers, no handed propellers) and refused to pay for them when production began after the BoB was over. They no longer needed them. Personally I believe that both the P-400 and Lightning II were ordered as ground attack planes. The P-400 was vastly overweight (excessive armor plate and .30cal wing guns) and the Lightning II had no turbochargers.


When the USA entered the war why werent the Tiger Squadrons in UK issued with P-39s? New production models may have small problems, the P-39s problems were those experienced with a prototype not a production model, the modifications took them up to what they should have been as production planes, Bell were using the RAF for product development, NA didnt do that with the Mustang1 neither did Curtiss with the P-40.

The P-38 is another issue, I believe the British took over the French order and the French ordered them with all Allison engines the same, unsupercharged and not handed to be the same as the P-40s they ordered. How many P-38s would the USA supply to UK after Dec 1941? My estimate is zero, what is yours?


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## buffnut453 (Jun 26, 2021)

IIRC the turbochargers were export controlled and so couldn't be fitted to P-38s sold overseas.

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## FLYBOYJ (Jun 26, 2021)

pbehn said:


> The P-38 is another issue, I believe the British took over the French order and the French ordered them with all Allison engines the same, unsupercharged and not handed to be the same as the P-40s they ordered.


I was told many years ago by fellow Lockheed employees who worked at the Burbank facility in the pre and post war years that the "castrated" P-38s were ordered by the British Purchasing Committee with a "wink and a handshake" behind the scenes as Lockheed did not have a contract for the next expected block of P-38s to be ordered and did not want to build aircraft "at risk" or with company funds, let alone shut down the production line. This alleged back door deal was mentioned in at least one publication, can't remember if it was Brody or Miller who mentioned this. I was told that the British never intended to purchase the P-38 in large numbers and this deal was done behind closed doors. I never did research the validity of this and I think this could be verified by contract dates.

Now back to the P-39, don't want to hijack this thread!

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## pbehn (Jun 26, 2021)

FLYBOYJ said:


> I was told many years ago by fellow Lockheed employees who worked at the Burbank facility in the pre and post war years that the "castrated" P-38s were ordered by the British Purchasing Committee with a "wink and a handshake" behind the scenes as Lockheed did not have a contract for the next expected block of P-38s to be ordered and did not want to build aircraft "at risk" or with company funds, let alone shut down the production line. This alleged back door deal was mentioned in at least one publication, can't remember if it was Brody or Miller who mentioned this. I was told that the British never intended to purchase the P-38 in large numbers and this deal was done behind closed doors. I never did research the validity of this and I think this could be verified by contract dates.
> 
> Now back to the P-39, don't want to hijack this thread!


Perfectly possible, or some similar variation that suited the politics of the day. When the P-51 is ordered as a dive bomber simply because it goes under a different budget column anything is possible. Until the USA was actually in the war it would suit all concerned for production lines to be kick started or kept running by others, even if only on paper.

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## 33k in the air (Jun 26, 2021)

P-39 Expert said:


> Remember for decades the P-39 in Soviet service was known as a tank buster? We know now that it was one of their primary air defense fighters, not a ground attack plane.



I would submit the nature of the type of aerial fighting done on the Eastern front was of a different character from that on the Western front.

Use any aircraft in the proper way and it can be successful. Use in a way that isn't really suited to its abilities, and the results likely aren't going to be good.

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## wuzak (Jun 27, 2021)

P-39 Expert said:


> The bugs were worked out in time for AAF service in 1942. Brand new production models all had numerous bugs to work out. The British didn't want those planes anyway. The Battle of Britain was past and they had adequate production of internal fighters to meet their needs. They did the same thing with P-38s ordered as Lightning II. They ordered them in wierd configurations (no turbochargers, no handed propellers) and refused to pay for them when production began after the BoB was over. They no longer needed them. Personally I believe that both the P-400 and Lightning II were ordered as ground attack planes. The P-400 was vastly overweight (excessive armor plate and .30cal wing guns) and the Lightning II had no turbochargers.



The original French/British order was for P-38s with the same engine in left and right hand booms and without turbo. The British took over the whole order after the fall of France. These would be Lightning Is.

The order was ammended in early 1941 so that the bulk of the order (roughly 5/6) would be Lightning II, with opposite hand engines and turbochargers..

The first Lightning I arrived in Britain in early 1942. After testing the orders for the Lightning I were cancelled.

Only one Lightning II made it to Britain. 28 Lightning IIs were built, but most of these went to the USAAF. The remaining orders under the British contract were completed as P-38F or P-38G, the USAAF taking over those orders.

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## Shortround6 (Jun 27, 2021)

P-39 Expert said:


> They ordered them in wierd configurations (no turbochargers, no handed propellers) and refused to pay for them when production began after the BoB was over. They no longer needed them.



again with the accusations?

Show some real proof. 

As shown above the bulk of the order was for handed propellers and turbochargers. 

the French and British ordered the early planes without turbos not because they were trying to get out of the contracts but because the US Gov wasn't allowing the turbos to be exported. 

When they ordered the planes the Merlin III was standard British fighter engine. When delivery time started the Merlin 45 and Merlin XX were the standard British fighter engines. 
Delivery of the Lighting II wouldn't have been until 1942.

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## pbehn (Jun 27, 2021)

Shortround6 said:


> When they ordered the planes the Merlin III was standard British fighter engine. When delivery time started the Merlin 45 and Merlin XX were the standard British fighter engines.
> Delivery of the Lighting II wouldn't have been until 1942.


Deliveries to UK of P-38s after Dec 1941 would total zero, even if they had all been paid for in advance, with the full agreement of the British, the US needed them most of all.


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## wuzak (Jun 27, 2021)

pbehn said:


> Deliveries to UK of P-38s after Dec 1941 would total zero, even if they had all been paid for in advance, with the full agreement of the British, the US needed them most of all.



I believe it was 4 - 3 Lightning Is and 1 Lightning II.

The Lightning I order was transferred to the USAAF when they were tested by the British. The instruction was to send no more.

The Lighting II order was also taken over by the USAAF.

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## wuzak (Jun 27, 2021)

Would the P-39 have been better ditching the 37mm and having 4 0.50" HMGs in the nose firing through the propeller arc?

Or 5, the above plus one firing through the hub?


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## pbehn (Jun 27, 2021)

wuzak said:


> I believe it was 4 - 3 Lightning Is and 1 Lightning II.
> 
> The Lightning I order was transferred to the USAAF when they were tested by the British. The instruction was to send no more.
> 
> The Lighting II order was also taken over by the USAAF.


It is absolutely in the US interest to supply at least one P-38 (or any other type) to the British, so it will be tested in the same environment as other British and captured fighters and results compared. The information and input of other eyes and ideas is worth much more than the price of one plane.

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## P-39 Expert (Jun 27, 2021)

wuzak said:


> Would the P-39 have been better ditching the 37mm and having 4 0.50" HMGs in the nose firing through the propeller arc?
> 
> Or 5, the above plus one firing through the hub?


My vote goes to a 20mm firing through the propeller hub and the two synchronized .50s. Same as the P-400 and P-39D-1. Until the K model of July 1942 and after which had the better gun bay heating system, then the 37mm was reliable enough. After that, either the 37mm or 20mm would have worked just fine.


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## P-39 Expert (Jun 27, 2021)

Shortround6 said:


> again with the accusations?
> 
> Show some real proof.
> 
> ...


Pretty much impossible to prove intent. You accuse Bell of being a bunch of lying criminals and you can't prove that either.


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## Greg Boeser (Jun 27, 2021)

Oh yeah? What about Brewster, Curtiss and Glenn Martin? Can you say Truman Commission?

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## SaparotRob (Jun 27, 2021)

I can say it but I’ll need to practice first.

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## pbehn (Jun 27, 2021)

P-39 Expert said:


> Pretty much impossible to prove intent. You accuse Bell of being a bunch of lying criminals and you can't prove that either.


It is routine to accuse the British of not taking the P-39 and P-38 because they didnt want to pay and finding spurious faults with them, at a time that hundreds of thousands of tons of shipping was being lost, a few planes was absolutely nothing but the point still gets made, doesnt it?


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## SaparotRob (Jun 27, 2021)

Wait a minute. Wasn't there something posted earlier about "dummy" (not really) orders just to keep Pre war American production lines open?


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## P-39 Expert (Jun 27, 2021)

wuzak said:


> I believe it was 4 - 3 Lightning Is and 1 Lightning II.
> 
> The Lightning I order was transferred to the USAAF when they were tested by the British. The instruction was to send no more.
> 
> The Lighting II order was also taken over by the USAAF.


The production table in The Lockheed P-38 Lightning by Warren Bodie shows 3+19 model 322-I, then 122 model 322-II to training command. The rest of the order completed at P-38Fs.


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## pbehn (Jun 27, 2021)

SaparotRob said:


> Wait a minute. Wasn't there something posted earlier about "dummy" (not really) orders just to keep Pre war American production lines open?


Yes, and such things did happen. still do, especially in neutral countries that have elections and big economies. There are many other reasons, I am sure there is some sort of reason for Greece having ordered 800+ Leopard I and II tanks, I cant think of a military one though.


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## SaparotRob (Jun 27, 2021)

I thought it may have had something to do with aircraft ultimately being rejected. Ordered but not needed.


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## FLYBOYJ (Jun 27, 2021)

P-39 Expert said:


> The production table in The Lockheed P-38 Lightning by Warren Bodie shows 3+19 model 322-I, then 122 model 322-II to training command. The rest of the order completed at P-38Fs.


I no longer have this book, what was produced before these numbers and what was the production date?


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## FLYBOYJ (Jun 27, 2021)

P-39 Expert said:


> Pretty much impossible to prove intent. You accuse Bell of being a bunch of lying criminals and you can't prove that either.


Not so much criminals, but maybe liars or "stretchers of the truth," but then again they weren't as bad as others.

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## pbehn (Jun 27, 2021)

SaparotRob said:


> I thought it may have had something to do with aircraft ultimately being rejected. Ordered but not needed.


If you change "needed" and "not needed" to "have something better" and "dont have anything better" things look much different. The Gloster Gladiator was used in Belgium, UK BoB and Malta because for various reasons the British didnt have anything better at the time, mainly to do with available runways and location. By 1941 the USA decided where the stuff they made would be sent on basis of need. The huge length of the Russian front meant that a use could be found for almost anything, the short length of the front in UK and its stretch of water meant that only the best could survive, even the Mustang MkI wasnt considered for use as a "fighter" in terms of defence or escort.

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## Shortround6 (Jun 27, 2021)

P-39 Expert said:


> Pretty much impossible to prove intent. You accuse Bell of being a bunch of lying criminals and you can't prove that either



Well, they advertised and sold a plane that was supposed to do 400mph. 
They flat out lied about the prototype ever doing 390-400mph. 
They spent hundreds of hours modifying one example for an acceptance test (using tricks that would never be used on production aircraft) just to meet the minimum qualify speed Several percent slower than the nominal contract speed. 
They later admitted that they had lied and and had based the performance number estimates off an unpainted, polished aircraft with no guns and little, if any, operational equipment that was a 1/2 ton lighter empty than the production aircraft. 

In fact the Bell executives, according to one account, admitted they used the figures from the XP-39 which was one ton lighter than even the P-39C which had NO armor, or self sealing tanks or IFF. and the first P-39C flew in Jan 1941. It was tested at a max speed of 379mph at a weight of 6689 lbs. see.
http://www.wwiiaircraftperformance.org/P-39/P-39C_40-2988.pdf

When tested at Boscombe Down A.H. 701 managed 355mph at 13,000ft. 

Perhaps the men at Bell weren't a bunch of lying criminals, perhaps they were just dishonest and incompetent. Or you pick a description that fits. 

You have yet to list the unnecessary equipment the British specified in order to "break" the contract. 
the 2nd Aircobra I (P-400) flew at the April 1941. The British had been fitting armor, self sealing tanks (of a limited sort) and IFF to their fighters for over 10 months. 

And now you claim the British specified a version of the P-38 with modifications to ruin it's performance to to point they could get out of the contract, as part of your proof you point to the lack of turbo chargers, but as been pointed out to you, at the time of the initial contract the British were not allowed to buy the turbo chargers. How was that the fault of the British? 

It is arguments like this that ruin your credibility and make people a lot less likely to listen to your other arguments.

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## P-39 Expert (Jun 28, 2021)

Shortround6 said:


> Well, they advertised and sold a plane that was supposed to do 400mph.
> They flat out lied about the prototype ever doing 390-400mph.
> They spent hundreds of hours modifying one example for an acceptance test (using tricks that would never be used on production aircraft) just to meet the minimum qualify speed Several percent slower than the nominal contract speed.
> They later admitted that they had lied and and had based the performance number estimates off an unpainted, polished aircraft with no guns and little, if any, operational equipment that was a 1/2 ton lighter empty than the production aircraft.
> ...


Bell believed they could get 400mph at the current weights when the engine would finally develop 1150HP at 15000' as was projected by Allison in late 1939. The weight went up drastically and the 1150HP at 15000' wasn't realized until fall of 1942 with the -85 engine. Their projections (and Allison's) were obviously off.

The British did specify a very heavy airplane at over 7600lbs, especially when their SpitfireV weighed in the neighborhood of 6600lbs. Four .30calMGs with 1000rounds per gun (almost 400lbs), nose armor and armor for the oxygen bottles etc, (about 140lbs), a fuel powered cabin heater (when heating/cooling of the cabin was actually already very good) among other items. British had to know that a plane half a ton heavier than a Spitfire had to have a performance penalty. And I have listed these items numerous times on this board.


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## buffnut453 (Jun 28, 2021)

P-39 Expert said:


> Bell believed they could get 400mph at the current weights when the engine would finally develop 1150HP at 15000' as was projected by Allison in late 1939. The weight went up drastically and the 1150HP at 15000' wasn't realized until fall of 1942 with the -85 engine. Their projections (and Allison's) were obviously off.
> 
> The British did specify a very heavy airplane at over 7600lbs, especially when their SpitfireV weighed in the neighborhood of 6600lbs. Four .30calMGs with 1000rounds per gun (almost 400lbs), nose armor and armor for the oxygen bottles etc, (about 140lbs), a fuel powered cabin heater (when heating/cooling of the cabin was actually already very good) among other items. British had to know that a plane half a ton heavier than a Spitfire had to have a performance penalty. And I have listed these items numerous times on this board.



And you've been told just as many times that the additional weight added by the British was NOT useless. The requirements were levied because that's what the customer wanted. They WANTED the wing guns because they were not useless (as you keep saying). They WANTED protection for the oxygen tanks because experience showed that unprotected oxygen was a combat liability (and they levied the same requirement on the Brewster Buffalo). 

Do you have evidence that the British mandated the nose armour because, from what I've seen, it was pretty much a standard fit on all P-39s? 

You can blame the Brits all you like but the bottom line is that the P-39 when configured for actual combat operations wasn't a very good aircraft. Period.

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## P-39 Expert (Jun 28, 2021)

FLYBOYJ said:


> I no longer have this book, what was produced before these numbers and what was the production date?


F-5A-10-LO from Nov 1942.


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## P-39 Expert (Jun 28, 2021)

Any way the title of this thread could be renamed "P-39 Continuing Thread" or something like that?

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## pbehn (Jun 28, 2021)

P-39 Expert said:


> Bell believed they could get 400mph at the current weights when the engine would finally develop 1150HP at 15000' as was projected by Allison in late 1939. The weight went up drastically and the 1150HP at 15000' wasn't realized until fall of 1942 with the -85 engine. Their projections (and Allison's) were obviously off.
> 
> The British did specify a very heavy airplane at over 7600lbs, especially when their SpitfireV weighed in the neighborhood of 6600lbs. Four .30calMGs with 1000rounds per gun (almost 400lbs), nose armor and armor for the oxygen bottles etc, (about 140lbs), a fuel powered cabin heater (when heating/cooling of the cabin was actually already very good) among other items. British had to know that a plane half a ton heavier than a Spitfire had to have a performance penalty. And I have listed these items numerous times on this board.


How much did the Mustang MkI weigh with the same engine and 4 cannon plus all the other stuff, how fast did it go?
By 1941 the Spitfire MkV was introduced, some carried 4 cannon AND 4 mgs.
By the end of 1942 the MkIX was in service, the Griffon powered Mk XII was being made and the Typhoon was getting sorted. We have been through all of this before.


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## special ed (Jun 28, 2021)

We could call it the "Repeat, repeat, deja vu all over again" thread.

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## buffnut453 (Jun 28, 2021)

P-39 Expert said:


> Any way the title of this thread could be renamed "P-39 Continuing Thread" or something like that?



The title of the thread is bang on target, per your post #1859 which perfectly reflects the title.


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## DerAdlerIstGelandet (Jun 28, 2021)

P-39 Expert said:


> Any way the title of this thread could be renamed "P-39 Continuing Thread" or something like that?



No, it can stay...

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## P-39 Expert (Jun 28, 2021)

buffnut453 said:


> And you've been told just as many times that the additional weight added by the British was NOT useless. The requirements were levied because that's what the customer wanted. They WANTED the wing guns because they were not useless (as you keep saying). They WANTED protection for the oxygen tanks because experience showed that unprotected oxygen was a combat liability (and they levied the same requirement on the Brewster Buffalo).
> 
> Do you have evidence that the British mandated the nose armour because, from what I've seen, it was pretty much a standard fit on all P-39s?
> 
> You can blame the Brits all you like but the bottom line is that the P-39 when configured for actual combat operations wasn't a very good aircraft. Period.


And I have replied at least as many times that no other fighter plane had an armored reduction gear or armored oxygen bottles (except the Brewster Buffalo). I never said the British mandated the nose armor, I just said the plane would improve without it.

And the .30cal wing guns were as close to worthless/redundant as you can get. Little hitting power, wide convergence and (the main reason) their effective range was only 200yds (AHT). 200yds is pretty darn close to be getting to a bomber that is shooting back. No P-38, P-40, P-47, P-51, F4F, F4U, F6F, B-17, B-24, B-25, B-26, or B-29 fought for the AAF/USN with .30cal MGs. Especially since the plane already had a 20mm cannon and twin .50cal MGs. Plenty of armament.

The Soviets configured the P-39 without the .30cal wing guns and they thought it was a really good aircraft. Their favorite.


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## pbehn (Jun 28, 2021)

P-39 Expert said:


> And I have replied at least as many times that no other fighter plane had an armored reduction gear or armored oxygen bottles (except the Brewster Buffalo). I never said the British mandated the nose armor, I just said the plane would improve without it.
> 
> And the .30cal wing guns were as close to worthless/redundant as you can get. Little hitting power, wide convergence and (the main reason) their effective range was only 200yds (AHT). 200yds is pretty darn close to be getting to a bomber that is shooting back. No P-38, P-40, P-47, P-51, F4F, F4U, F6F, B-17, B-24, B-25, B-26, or B-29 fought for the AAF/USN with .30cal MGs. Especially since the plane already had a 20mm cannon and twin .50cal MGs. Plenty of armament.
> 
> The Soviets configured the P-39 without the .30cal wing guns and they thought it was a really good aircraft. Their favorite.


Where is this armoured oxygen bottle?


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## glennasher (Jun 28, 2021)

P-39 Expert said:


> And I have replied at least as many times that no other fighter plane had an armored reduction gear or armored oxygen bottles (except the Brewster Buffalo). I never said the British mandated the nose armor, I just said the plane would improve without it.
> 
> And the .30cal wing guns were as close to worthless/redundant as you can get. Little hitting power, wide convergence and (the main reason) their effective range was only 200yds (AHT). 200yds is pretty darn close to be getting to a bomber that is shooting back. No P-38, P-40, P-47, P-51, F4F, F4U, F6F, B-17, B-24, B-25, B-26, or B-29 fought for the AAF/USN with .30cal MGs. Especially since the plane already had a 20mm cannon and twin .50cal MGs. Plenty of armament.
> 
> The Soviets configured the P-39 without the .30cal wing guns and they thought it was a really good aircraft. Their favorite.


Apparently you're forgetting that the Brits had already fought BoB with Hurricanes and Spitfires armed with .30 caliber machine guns, and did "fairly well" with them. The US .30/06 is a bit better cartridge than the British .303, too. The Germans had 7.92 machine guns in their aircraft, which might as well be .30s (okay, they are .32s, not that it matters).

The Russians were fighting a different war than were the Brits, that cannot be emphasized enough, they were fighting a different war. You always seem to gloss over that, but the needs/wants were completely at odds with one another. The Russians weren't paying for P-39s and didn't give a crap about wearing out motors, either.
Just because "the Russians liked them" doesn't mean, by any stretch whatsoever, that the aircraft was worth a tinker's damn anywhere but on the Eastern front. And it wasn't much count anywhere EXCEPT the Russian front, either, as many others here have shown you, many, many times.

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## nuuumannn (Jun 28, 2021)

pbehn said:


> The information and input of other eyes and ideas is worth much more than the price of one plane.



Completely agree. The use of US combat types by foreign air forces prior to the Americans joining the war gave the US forces a huge amount of valuable experience and knowledge that quite often goes unappreciated, particularly by Americans. Almost all the major US combat types in WW2 saw service with foreign air forces before the US entered the war, the PBY, P-39, P-40, P-36, F4F, B-24, B-17, P-51 etc, etc. British experience with the B-17 as the Fortress I is a good example, the B-17C was just not up to the task that the USAAC/F was expecting of it over Europe in 1941, suffering poor serviceability, high losses to enemy fighters and poor defensive armament, as well as an inability to function properly at the heights the bomber was designed to function at, with equipment routinely freezing and becoming inoperable.

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## pbehn (Jun 28, 2021)

nuuumannn said:


> Completely agree. The use of US combat types by foreign air forces prior to the Americans joining the war gave the US forces a huge amount of valuable experience and knowledge that quite often goes unappreciated, particularly by Americans. Almost all the major US combat types in WW2 saw service with foreign air forces before the US entered the war, the PBY, P-39, P-40, P-36, F4F, B-24, B-17, P-51 etc, etc. British experience with the B-17 as the Fortress I is a good example, the B-17C was just not up to the task that the USAAC/F was expecting of it over Europe in 1941, suffering poor serviceability, high losses to enemy fighters and poor defensive armament, as well as an inability to function properly at the heights the bomber was designed to function at, with equipment routinely freezing and becoming inoperable.


In terms of the thread, it illustrates the difference between an independent test and one done by the people who made the plane. Bell were gaming the system to their advantage, the tests didnt represent what they were selling as production models to the agreed spec.

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## pbehn (Jun 28, 2021)

P-39 Expert said:


> The Soviets configured the P-39 without the .30cal wing guns and they thought it was a really good aircraft. Their favorite.


Since we are back in full groundhog mode, can we agree that the UK isnt Russia?

By 1941 the standard armament on UK fighters was 4 x 20mm cannon. The Spitfire was an exception because of the need for altitude performance and heating. They had a different use to that in Russia that is why they needed different armament, this is why you need to accept Russia isnt England, then we can move on, in small steps.


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## nuuumannn (Jun 28, 2021)

pbehn said:


> Since we are back in full groundhog mode, can we agree that the UK isnt Russia?



Golden!


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## buffnut453 (Jun 28, 2021)

P-39 Expert said:


> And I have replied at least as many times that no other fighter plane had an armored reduction gear or armored oxygen bottles (except the Brewster Buffalo). I never said the British mandated the nose armor, I just said the plane would improve without it.
> 
> And the .30cal wing guns were as close to worthless/redundant as you can get. Little hitting power, wide convergence and (the main reason) their effective range was only 200yds (AHT). 200yds is pretty darn close to be getting to a bomber that is shooting back. No P-38, P-40, P-47, P-51, F4F, F4U, F6F, B-17, B-24, B-25, B-26, or B-29 fought for the AAF/USN with .30cal MGs. Especially since the plane already had a 20mm cannon and twin .50cal MGs. Plenty of armament.
> 
> The Soviets configured the P-39 without the .30cal wing guns and they thought it was a really good aircraft. Their favorite.



Firstly, the RAF did not specify 30cals. They specified the ability to fit .303s which would be Government Furnished Equipment installed when the aircraft were erected in the UK. Different weapon, different capabilities. Again, it's YOUR assessment that the 30cals were useless. The fact that the RAF continued with .303s even after the introduction of 20mm cannon as the main fighter armament suggests that they weren't useless. The fact that the USAAF operating the P-400s and P-39s under combat conditions also didn't remove the wing 30 cals suggests rather strongly that they were beneficial. Just because the Russians removed the wing guns does not mean that was a workable solution in other theatres. You have been told this DOZENS of times and yet you still persist in your belief that the 30cal/.303 was useless. Sorry but you can't use your own incorrect statement as evidence of malfeasance by the Brits. 

(Yet) again, the RAF was using .303s when the P-39 was ordered and they were still using them in fighters long after they, rightly, shit-canned the P-39 as a waste of time. The RAF was the customer. They had the combat experience in the theatres where they were fighting. No amount of armchair generalling, particularly from someone who is so intent on not listening to anyone else, will convince me that they were wrong to specify the .303s. As to your long list of American aircraft that didn't use 30 cals...that's ENTIRELY irrelevant because the CUSTOMER was the RAF. 

You said "I never said the British mandated the nose armor, I just said the plane would improve without it" and yet in post 1589 you said "The British did specify a very heavy airplane at over 7600lbs, especially when their SpitfireV weighed in the neighborhood of 6600lbs. Four .30calMGs with 1000rounds per gun (almost 400lbs), nose armor and armor for the oxygen bottles etc, (about 140lbs), a fuel powered cabin heater (when heating/cooling of the cabin was actually already very good) among other items" which clearly suggests that the RAF specified all those items, including the nose armour. And, YET AGAIN, people have explained why it was necessary for both weight and balance and because of the P-39's unique configuration which meant that damage to the gearbox would result in a whiplashing drive shaft that ran between the pilots legs. And you ask why this is the groundhog day thead?

As to the oxygen tank, was it actually armour-plated or simply afforded greater protection? Looking at the location, I can't help wondering if there were concerns about oxygen leaking from a damaged tank being ignited by the guns firing. Certainly, most other fighter aircraft of the period had the oxygen tank aft of the cockpit. Again, the P-39s unique configuration forced the tank to be moved forward...so perhaps putting it the gun bay wasn't the brightest idea?

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## pbehn (Jun 28, 2021)

nuuumannn said:


> Golden!


Since some Spitfires had no guns at all I really dont know what the discussion is about. The British had to shoot down what came across the channel whatever that was and it became V1s, and perform armed recon, completely different to what was needed in Russia.

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## wuzak (Jun 28, 2021)

P-39 Expert said:


> The British did specify a very heavy airplane at over 7600lbs, especially when their SpitfireV weighed in the neighborhood of 6600lbs. Four .30calMGs with 1000rounds per gun (almost 400lbs), nose armor and armor for the oxygen bottles etc, (about 140lbs), a fuel powered cabin heater (when heating/cooling of the cabin was actually already very good) among other items. British had to know that a plane half a ton heavier than a Spitfire had to have a performance penalty. And I have listed these items numerous times on this board.



US aircraft seemed to have heavier structures than their UK counterparts.

And note that the Spitfire at 6,600lb had two 20mm cannon and 4 0.303" lmgs, plus armour and self sealing fuel tanks. So the extra weight of the P-39 is likely not totally due to the items you list, particulalry when some of those items were also on the Spitfire.

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## wuzak (Jun 28, 2021)

P-39 Expert said:


> And the .30cal wing guns were as close to worthless/redundant as you can get. Little hitting power, wide convergence and (the main reason) their effective range was only 200yds (AHT). 200yds is pretty darn close to be getting to a bomber that is shooting back. No P-38, P-40, P-47, P-51, F4F, F4U, F6F, B-17, B-24, B-25, B-26, or B-29 fought for the AAF/USN with .30cal MGs.



The P-40B or C must, surely, have flown in combat, some of those being at Pearl Harbor when teh Japanese attacked. They had 2 0.50" hmgs in the cowl and 4 0.30"lmgs in the wings.




P-39 Expert said:


> Especially since the plane already had a 20mm cannon and twin .50cal MGs. Plenty of armament.



Plenty of armament to fight against?

What was the firing time for each of those weapons? 6 seconds for the 20mm?

It would be handy to have smaller calibre weapons available when the main guns ran out of ammunition.


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## Greg Boeser (Jun 29, 2021)

Re: .30 caliber MGs
USAAF aircraft equipped with this weapon at the end of 1941
P-26
P35A
P-36A
P-39D/P-400
P-40B and C
A-20A
A-24
Most bombers at this date (B-17, B-18, B-24, B25, B-26) carried a mix of .50 and .30 caliber guns for defense.

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## buffnut453 (Jun 29, 2021)

P-39 Expert said:


>





Greg Boeser said:


> Re: .30 caliber MGs
> USAAF aircraft equipped with this weapon at the end of 1941
> P-26
> P35A
> ...



And the supreme irony in his bringing up all those aircraft without 30cals is that the P-39D WAS equipped with 30cals. The comedy value is priceless.


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## Shortround6 (Jun 29, 2021)

P-39 Expert said:


> Bell believed they could get 400mph at the current weights when the engine would finally develop 1150HP at 15000' as was projected by Allison in late 1939. The weight went up drastically and the 1150HP at 15000' wasn't realized until fall of 1942 with the -85 engine. Their projections (and Allison's) were obviously off.
> 
> The British did specify a very heavy airplane at over 7600lbs, especially when their SpitfireV weighed in the neighborhood of 6600lbs. Four .30calMGs with 1000rounds per gun (almost 400lbs), nose armor and armor for the oxygen bottles etc, (about 140lbs), a fuel powered cabin heater (when heating/cooling of the cabin was actually already very good) among other items. British had to know that a plane half a ton heavier than a Spitfire had to have a performance penalty. And I have listed these items numerous times on this board.



Well, adding guns will certainly increase the weight of an unarmed prototype.
Bell should have paid more attention to the air intake, P-40s with the -39 engine could hold 1150hp to over 14,000ft in level flight even if not in a climb.
Was Allison promising 1150hp at 15,000ft with or without RAM?
The failed Allison engines with the too narrow 9.60 gears didn't show up until around Dec of 1941. Two years after Allison was promising 1150hp at 15,000ft? 

As for the British specifying the weight, They didn't.
The P-39C was already heavier than the Spitfire V.
Was the USAAC trying to get out of the contract by specifying useless stuff?
P-39 had about 50lbs worth of drive shaft that the Spitfire didn't.
P-39 had a heavier, stiffer fuselage than the Spitfire. Around 50lbs more than a conventional fuselage according to one account.
P-39 had about 128lbs worth of nose landing gear, Much heavier than the tail wheel of the Spitfire.
The P-400 was built to US strength/stress standards, not British standards. 


as to the .30 cal gun thing, well covered by others except the fact is that the British were NOT the ones who ordered the wing guns, The French did. Were the US fell in I don't know. Last 60 P-39Cs on the initial order were completed as P-39Ds with the two worthless .30 cal cowl guns moved out to the wings and another gun added in each wing. Did the British "order" the wing guns or just fall in line with French and Americans? 

For your allegation to be true we would have to have some British agent talking to the French in late 1939, very early 1940 ad telling them
"_why don't you chaps ask Bell to put four 7.5 machine guns out in the wing so the plane will be heavier, this is so that after Germany beats you and we take over the contract we can get out of the contract when America comes up with lend lease over a year in the Future._"

As an historic note the British also ordered 620 Mustang Is with Allison engines and four .50 cal guns and four .303s.
The Curtiss P-46 prototype had two.50s and eight .303s.
The Hurricane IIB had twelve .303s as did the early Typhoon. 
The Fulmar defended the Med convoys using eight .303s. Many Italian and German aviators would be really discouraged to find out they were shoot down by worthless guns/ammo. 

In 1940 the 20mm Hispano and the US .50 were both immature weapons systems. 

Another historic note, The Japanese used the very same 7.7/.303 cartridge in their version of a Vickers gun (licensed) in the Zero, the Ki-43, the Ki 27, the A5M, the Val and a host of other aircraft, they seemed to do pretty well with it in 1941/42, perhaps they mostly held their fire until the were within 200yds? 

I don't

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## pbehn (Jun 29, 2021)

Shortround6 said:


> "_why don't you chaps ask Bell to put four 7.5 machine guns out in the wing so the plane will be heavier, this is so that after Germany beats you and we take over the contract we can get out of the contract when America comes up with lend lease over a year in the Future._"


Then instead of being given P-39s we will be given something better. 

The whole argument of cost is a nonsense, there were and still are more aircraft on the Atlantic sea bed than and UK order of P-39s.


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## Peter Gunn (Jun 29, 2021)

P-39 Expert said:


> Any way the title of this thread could be renamed "P-39 Continuing Thread" or something like that?


No.


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## Peter Gunn (Jun 29, 2021)

P-39 Expert said:


> And I have replied at least as many times that no other fighter plane had an armored reduction gear or armored oxygen bottles (except the Brewster Buffalo). I never said the British mandated the nose armor, I just said the plane would improve without it.
> 
> And the .30cal wing guns were as close to worthless/redundant as you can get. Little hitting power, wide convergence and (the main reason) their effective range was only 200yds (AHT). 200yds is pretty darn close to be getting to a bomber that is shooting back. *No* P-38, P-40, P-47, *P-51*, F4F, F4U, F6F, B-17, B-24, B-25, B-26, or B-29 fought for the AAF/USN with .30cal MGs. Especially since the plane already had a 20mm cannon and twin .50cal MGs. Plenty of armament.
> 
> The Soviets configured the P-39 without the .30cal wing guns and they thought it was a really good aircraft. Their favorite.


I'm sorry, did I miss the memo on the early Mustangs _not_ having 4 .30's and 4 .50's?


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## pbehn (Jun 29, 2021)

Peter Gunn said:


> I'm sorry, did I miss the memo on the early Mustangs _not_ having 4 .30's and 4 .50's?


And later ones having 4 20mm cannon. Unlike Bell, North American just put in, or on or under what the client told them to. Camera sir, in the back sir? certainly sir, will look lovely! Or would sir like a tail warning radar?

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## Clayton Magnet (Jun 29, 2021)

wuzak said:


> The P-40B or C must, surely, have flown in combat, some of those being at Pearl Harbor when teh Japanese attacked. They had 2 0.50" hmgs in the cowl and 4 0.30"lmgs in the wings.
> 
> 
> 
> ...


Did the P-400 pre-date the belt fed Hispano?
I would agree with the resident expert, that 2 .50's and a central 20mm cannon was plenty of firepower, BUT, only assuming they could get a reasonable rate of fire out of the synchronized Brownings and a belt feed for the 20mm

Trying to supply three different ammunition types to the aircraft seems like it would be a logistical issue


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## 33k in the air (Jun 29, 2021)

Clayton Magnet said:


> BUT, only assuming they could get a reasonable rate of fire out of the synchronized Brownings and a belt feed for the 20mm



I think the ill-fated XP-75 wins there: four nose-mounted .50-cal guns firing through contra-rotating props. The rate of fire couldn't have been great. But at least is still had its six wing-mounted .50 cal MGs.


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## pbehn (Jun 29, 2021)

Clayton Magnet said:


> Did the P-400 pre-date the belt fed Hispano?
> I would agree with the resident expert, that 2 .50's and a central 20mm cannon was plenty of firepower, BUT, only assuming they could get a reasonable rate of fire out of the synchronized Brownings and a belt feed for the 20mm
> 
> Trying to supply three different ammunition types to the aircraft seems like it would be a logistical issue


He is actually talking about late 1942 for most things but projecting onto the first P-39s delivered to UK in August 1941, obviously the XP39 was tested in USA long before that (Aug 1940 I think) If a fully functioning 20mm cannon was available in 1940, the British would have been using it. If the 0.5" MG worked in 1940 as it did in 1943/44 the British may also have used that, but they didnt and werent.


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## Clayton Magnet (Jun 29, 2021)

If we are talking about an early drum fed Hispano, with 6 seconds of ammunition and liable to jam on the first shot, combined with early synchronized Browning M2's, firing at 450 rounds per minute and liable to jam under slight g-loading, then yes, the wing mounted 30 caliber (.303?) machine guns would probably be a welcome addition.

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## pbehn (Jun 29, 2021)

Clayton Magnet said:


> If we are talking about an early drum fed Hispano, with 6 seconds of ammunition and liable to jam on the first shot, combined with early synchronized Browning M2's, firing at 450 rounds per minute and liable to jam under slight g-loading, then yes, the wing mounted 30 caliber (.303?) machine guns would probably be a welcome addition.


This is why it is a groundhog thread, jumping endlessly though space and time.

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## 33k in the air (Jun 29, 2021)

pbehn said:


> This is why it is a groundhog thread, jumping endlessly though space and time.



Well, time travel is the best travel!


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## SaparotRob (Jun 29, 2021)

The British do indeed believe in traveling well.


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## pbehn (Jun 29, 2021)

SaparotRob said:


> The British do indeed believe in traveling well.


 With lots of rifle calibre guns and ammo.

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## P-39 Expert (Jun 29, 2021)

glennasher said:


> Apparently you're forgetting that the Brits had already fought BoB with Hurricanes and Spitfires armed with .30 caliber machine guns, and did "fairly well" with them. The US .30/06 is a bit better cartridge than the British .303, too. The Germans had 7.92 machine guns in their aircraft, which might as well be .30s (okay, they are .32s, not that it matters).
> 
> The Russians were fighting a different war than were the Brits, that cannot be emphasized enough, they were fighting a different war. You always seem to gloss over that, but the needs/wants were completely at odds with one another. The Russians weren't paying for P-39s and didn't give a crap about wearing out motors, either.
> Just because "the Russians liked them" doesn't mean, by any stretch whatsoever, that the aircraft was worth a tinker's damn anywhere but on the Eastern front. And it wasn't much count anywhere EXCEPT the Russian front, either, as many others here have shown you, many, many times.


Yes, the Brits fought the BoB with .30s but they upgraded to 20mm cannons as soon as they could. Many stories of Spitfires/Hurricanes emptying their magazines into German bombers just to see them fly on unimpeded.

The Soviets were certainly fighting about the same war as the BoB. Intercepting medium altitude bombers and higher altitude fighters. The Soviets with the P-39 fought the LW at all altitudes in all conditions.


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## FLYBOYJ (Jun 29, 2021)

P-39 Expert said:


> The Soviets were certainly fighting about the same war as the BoB. Intercepting medium altitude bombers and higher altitude fighters. The Soviets with the P-39 fought the LW at all altitudes in all conditions.


Except over the North Sea

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## pbehn (Jun 29, 2021)

P-39 Expert said:


> Yes, the Brits fought the BoB with .30s but they upgraded to 20mm cannons as soon as they could. Many stories of Spitfires/Hurricanes emptying their magazines into German bombers just to see them fly on unimpeded.
> 
> The Soviets were certainly fighting about the same war as the BoB. Intercepting medium altitude bombers and higher altitude fighters. The Soviets with the P-39 fought the LW at all altitudes in all conditions.


No they were not, how can you make and continue to make that assertion, it is beyond ridiculous.


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## 33k in the air (Jun 29, 2021)

P-39 Expert said:


> The Soviets were certainly fighting about the same war as the BoB. Intercepting medium altitude bombers and higher altitude fighters. The Soviets with the P-39 fought the LW at all altitudes in all conditions.



What are the actual altitude bands? What is low altitude, what is medium altitude, and what is high altitude? In feet or metres.


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## P-39 Expert (Jun 29, 2021)

Shortround6 said:


> Well, adding guns will certainly increase the weight of an unarmed prototype.
> Bell should have paid more attention to the air intake, P-40s with the -39 engine could hold 1150hp to over 14,000ft in level flight even if not in a climb.
> Was Allison promising 1150hp at 15,000ft with or without RAM?
> The failed Allison engines with the too narrow 9.60 gears didn't show up until around Dec of 1941. Two years after Allison was promising 1150hp at 15,000ft?
> ...


You are continuing with the circular argument here. We've discussed this many times before and you keep bringing it up.

The .30 wing guns were added to the P-400 in March 1940. France had not yet capitulated but who was running the P-400 contract at that time? France or Britain? The P-400 would weigh 7850lbs after the British got finished with it, as compared with a Spitfire V at 6600lbs. The British knew full well the weight penalty on performance involved. 

Either way, the P-39C was being produced Jan-March 1941 and was on the right track to be a very potent warplane for 1941. It grossed 7075lbs and would go 379mph and climb at 3720fpm, both better than a Spitfire V. The P-39-C did not have self sealing fuel tanks or pilot armor. Adding the self sealing tanks (240lbs), armor plate (120lbs as in the P-39N without the nose armor) and an additional 15 rounds of 37mm ammo (30lbs) should have been offset by removing the two .30s in the nose (100lbs) and the 50gal fuel not available after installation of the self sealing tanks (300lbs) for a net reduction of 10lbs.

The P-39D which began production in April 1941 could easily have weighed 7150lbs, only 75lbs more than the P-39C. Empty Weight 5523lbs, Pilot 160lbs, 37mm cannon and two .50calMGs with ammunition and gun sight 580lbs, Fuel (120gal) 720lbs, Oil 71lbs, armor plate and glass (as above) 120lbs, oxygen 8lbs. Total 7182lbs. Deduct 32lbs for the wing .30cal gun mounts, chargers, heaters and ammunition boxes and you have 7150lbs. Substitute the more reliable (at that time) 20mm cannon and deduct 130lbs for a new gross weight of 7020lbs. Both versions about the same performance as the 7075lb P-39C, 379mph and 3720fpm climb. A heavily armed and armored warplane available from April 1941.


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## P-39 Expert (Jun 29, 2021)

33k in the air said:


> What are the actual altitude bands? What is low altitude, what is medium altitude, and what is high altitude? In feet or metres.


I haven't seen actual numbers, but I always use 0-10000ft for low altitude, 10000-20000ft for medium altitude, and over 20000ft for high altitude.


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## P-39 Expert (Jun 29, 2021)

pbehn said:


> No they were not, how can you make and continue to make that assertion, it is beyond ridiculous.


Only difference between air combat in western Europe and eastern Europe was there were no high altitude bombers in Eastern Europe. And those weren't really a force in the west until mid '43. Soviets standard combat formation was the "Kuban Stairs" or "Flying Bookshelves" with a flight (4 planes) at 5000meters (16500ft), a flight at 6000meters (20000ft) and the top flight at 7000meters (23000ft). P-39s could match the LW fighters up to 8000meters (26400ft) with neither side willing to go much higher than that. 

Turbocharged B-17s and B-24s flew at 25000ft with their escorts a little higher. Not much difference.


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## Glider (Jun 29, 2021)

P-39 Expert said:


> You are continuing with the circular argument here. We've discussed this many times before and you keep bringing it up.
> 
> The .30 wing guns were added to the P-400 in March 1940. France had not yet capitulated but who was running the P-400 contract at that time? France or Britain? The P-400 would weigh 7850lbs after the British got finished with it, as compared with a Spitfire V at 6600lbs. The British knew full well the weight penalty on performance involved.
> 
> ...


And yet no one made these simple changes. Strange that isn't it.


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## pbehn (Jun 29, 2021)

P-39 Expert said:


> Only difference between air combat in western Europe and eastern Europe was there were no high altitude bombers in Eastern Europe. And those weren't really a force in the west until mid '43. Soviets standard combat formation was the "Kuban Stairs" or "Flying Bookshelves" with a flight (4 planes) at 5000meters (16500ft), a flight at 6000meters (20000ft) and the top flight at 7000meters (23000ft). P-39s could match the LW fighters up to 8000meters (26400ft) with neither side willing to go much higher than that.
> 
> Turbocharged B-17s and B-24s flew at 25000ft with their escorts a little higher. Not much difference.


You never clarified that you know the difference between UK and Russia, now could you clarify that you understand B-17 and B-24s were intercepted by GERMAN not allied fighters? The Battle of Britain took place at up to and slightly over 30,000ft. The normal altitude for UK offensive operations with bombers was 15,000 ft. The coast of France and Belgium was a picket line of flak, what are you going to use you P-39s for?


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## P-39 Expert (Jun 29, 2021)

Clayton Magnet said:


> Did the P-400 pre-date the belt fed Hispano?
> I would agree with the resident expert, that 2 .50's and a central 20mm cannon was plenty of firepower, BUT, only assuming they could get a reasonable rate of fire out of the synchronized Brownings and a belt feed for the 20mm
> 
> Trying to supply three different ammunition types to the aircraft seems like it would be a logistical issue


The P-400 was produced from July 1941. The Spitfire V had 120rds of belt fed ammunition by then, the P-38E had 150rds from October '41 and the P-51(no suffix) had four with 120rds from July '42 (AHT). First real combat for the P-39/400 was April '42.

Trying to supply three different ammo types was insane. Especially when the .30s had an effective range of only 200yds (AHT). And the AAF really had to supply FOUR different ammo types, since P-400s and P-39D-1s with 20mm cannons were often mixed in with the 37mm types. Double insane. Just standardize on the 20mm and 50cal like the P-38. Hindsight.


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## pbehn (Jun 29, 2021)

P-39 Expert said:


> The P-400 was produced from July 1941. The Spitfire V had 120rds of belt fed ammunition by then, the P-38E had 150rds from October '41 and the P-51(no suffix) had four with 120rds from July '42 (AHT). First real combat for the P-39/400 was April '42.
> 
> Trying to supply three different ammo types was insane. Especially when the .30s had an effective range of only 200yds (AHT). And the AAF really had to supply FOUR different ammo types, since P-400s and P-39D-1s with 20mm cannons were often mixed in with the 37mm types. Double insane. Just standardize on the 20mm and 50cal like the P-38. Hindsight.


But Bell hadnt supplied any aircraft by then had they? So no one had any chance to work on it had they? When they did get the aircraft they were too busy working on other things, werent they? The first real combat of the P-39 was as you say, and marginally before the first real combat of the Spitfire IX and the Mustang MkI. You cannot standardise on a weapon that doesnt work, just because it worked later.


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## Clayton Magnet (Jun 29, 2021)

P-39 Expert said:


> Just standardize on the 20mm and 50cal like the P-38. Hindsight.


If we are revising history with hindsight, then scrap the 50cal AND the P-39, and standardize on 20mm cannons and P-51's. Seems like a win-win.
Use Oerlikon FFL's until the Hispano is satisfactorily sorted out.

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## pbehn (Jun 29, 2021)

Clayton Magnet said:


> If we are revising history with hindsight, then scrap the 50cal AND the P-39, and standardize on 20mm cannons and P-51's. Seems like a win-win.
> Use Oerlikon FFL's until the Hispano is satisfactorily sorted out.


Everything that was available in 1942 is now available in 1939, a new game, lets go.


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## ThomasP (Jun 29, 2021)

Er . . . wait now . . . groundhogs can time travel?

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## P-39 Expert (Jun 29, 2021)

pbehn said:


> You never clarified that you know the difference between UK and Russia, now could you clarify that you understand B-17 and B-24s were intercepted by GERMAN not allied fighters? The Battle of Britain took place at up to and slightly over 30,000ft. The normal altitude for UK offensive operations with bombers was 15,000 ft. The coast of France and Belgium was a picket line of flak, what are you going to use you P-39s for?


BoB got nowhere near 30000ft. Spitfire and 109E combat ceilings (1000fpm climb) were a little above 25000'. 110s about 21000ft. He111 ABSOLUTE ceiling was 22000ft. Nobody going near 30000ft, much less over except possibly recon missions. I cringe when I hear 30000ft in WWII.

B-17 and B-24 were intercepted by German fighters which seldom got over 26000ft. I don't really get your point, except to imply that I don't know the difference between UK and Russia. The UK drinks whiskey and Russians drink vodka. Got it. Thanks.


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## SaparotRob (Jun 29, 2021)

ThomasP said:


> Er . . . wait now . . . groundhogs can time travel?


P-39 vs. Fokker D-7?


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## buffnut453 (Jun 29, 2021)

P-39 Expert said:


> BoB got nowhere near 30000ft. Spitfire and 109E combat ceilings (1000fpm climb) were a little above 25000'. 110s about 21000ft. He111 ABSOLUTE ceiling was 22000ft. Nobody going near 30000ft, much less over except possibly recon missions. I cringe when I hear 30000ft in WWII.



Then feel free to cringe away...unless you think Flt Lt Eric Thomas was lying in his combat report for 9 October 1940:

_I was leading the Squadron on patrol at 30,000 feet roughly over Chatham. I followed 41 Squadron down to 28,000 feet and then saw about 5 Me.109's directly above at 29,000 feet. I climbed up into them and they made for a layer of cirrus, through which I followed them. I increased revs. to 3000 and gradually outclimbed them and gave a 4 seconds burst into the belly of one enemy aircraft._

How on earth did he get his Spitfire to 30,000ft if the aircraft had a service ceiling of "a little above 25000'?

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## pbehn (Jun 29, 2021)

P-39 Expert said:


> BoB got nowhere near 30000ft. Spitfire and 109E combat ceilings (1000fpm climb) were a little above 25000'. 110s about 21000ft. He111 ABSOLUTE ceiling was 22000ft. Nobody going near 30000ft, much less over except possibly recon missions. I cringe when I hear 30000ft in WWII.
> 
> B-17 and B-24 were intercepted by German fighters which seldom got over 26000ft. I don't really get your point, except to imply that I don't know the difference between UK and Russia. The UK drinks whiskey and Russians drink vodka. Got it. Thanks.


Page 345 of Bungay's The Most Dangerous Enemy QUOTE "Intercepting the Jabos and their escorts which flew in at over 30,000ft was causing Park some problems", Lots of your posts make me cringe, now do you agree that the UK and Russia are not the same place, and that it was German planes not P-39s that would intercept B-17s and B24s, every baby step is progress.

By the time your favoured P-39 was introduced the RAF had intercepted a German recon plane carrying bombs at 42,000ft August 1942.

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## buffnut453 (Jun 29, 2021)

Or John Gillespie Magee, describing how he came up with that brilliant poem "High Flight": 

“I am enclosing a verse I wrote the other day. It started at 30,000 feet, and was finished soon after I landed. I thought it might interest you.”

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## pbehn (Jun 29, 2021)

buffnut453 said:


> Then feel free to cringe away...unless you think Flt Lt Eric Thomas was lying in his combat report for 9 October 1940:
> 
> _I was leading the Squadron on patrol at 30,000 feet roughly over Chatham. I followed 41 Squadron down to 28,000 feet and then saw about 5 Me.109's directly above at 29,000 feet. I climbed up into them and they made for a layer of cirrus, through which I followed them. I increased revs. to 3000 and gradually outclimbed them and gave a 4 seconds burst into the belly of one enemy aircraft._
> 
> How on earth did he get his Spitfire to 30,000ft if the aircraft had a service ceiling of "a little above 25000'?


There were two issues, Chain Home became increasingly unreliable at those altitudes, and it was impossible to tell if a Bf109 was a "jabo" or just a fighter unless you had a plane there. Spitfires could cruise at 27,000ft, Bf109s without bombs could and did go over 30,000ft so they increasingly just looked at each other, unless there was a Bf109 with a bomb. (same page as previous, I hope no one cringes).

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## pbehn (Jun 29, 2021)

buffnut453 said:


> Or John Gillespie Magee, describing how he came up with that brilliant poem "High Flight":
> 
> “I am enclosing a verse I wrote the other day. It started at 30,000 feet, and was finished soon after I landed. I thought it might interest you.”


That is definitely a winner.

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## Glider (Jun 29, 2021)

buffnut453 said:


> How on earth did he get his Spitfire to 30,000ft if the aircraft had a service ceiling of "a little above 25000'?


He lightened it and put in a bigger engine, simple really


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## pbehn (Jun 29, 2021)

Glider said:


> He lightened it and put in a bigger engine, simple really


Is there any info on gearbox armour?

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## Glider (Jun 29, 2021)

pbehn said:


> Is there any info on gearbox armour?


No but I think they took out the IFF and moved the radio

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## P-39 Expert (Jun 29, 2021)

pbehn said:


> Page 345 of Bungay's The Most Dangerous Enemy QUOTE "Intercepting the Jabos and their escorts which flew in at over 30,000ft was causing Park some problems", Lots of your posts make me cringe, now do you agree that the UK and Russia are not the same place, and that it was German planes not P-39s that would intercept B-17s and B24s, every baby step is progress.
> 
> By the time your favoured P-39 was introduced the RAF had intercepted a German recon plane carrying bombs at 42,000ft August 1942.


I just have a hard time believing those accounts. With the altitude statistics of the day. A FW190 of 1943 (three years after the BoB) had a combat ceiling (climb 1000fpm) of 8000meters (26400ft). And you're telling me Spitfire I and 109E in 1940 routinely got over 30000ft? The LW bombers came in well under 20000ft. Why in the world would anyone try to get to 30000ft? Like the famous Darwin Australia raids that reportedly came in at 30000ft, none of the aircraft involved had combat ceilings (or for the bombers even service ceilings) even close to that.

Now maybe once in a blue moon, but routinely why would any of the fighters fly higher than even 5000ft above the bombers? It was possible but highly improbable especially on a routine basis. These were personal accounts, amounting to heresay. Maybe they read their instruments incorrectly, or they were embellishing their story. I don't know. But the equipment involved just wouldn't do that. I cringe when I hear 30000ft in WWII, unless they were escorting B-17/24s and then they were still well under 30000ft. Just my opinion.


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## Milosh (Jun 29, 2021)

Yes Spitfire I's had a service ceiling of over 30000ft.

The Mitsubishi G3M2 Model 21 had a service of just over 30000ft.


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## buffnut453 (Jun 29, 2021)

Milosh said:


> Yes Spitfire I's had a service ceiling of over 30000ft.
> 
> The Mitsubishi G3M2 Model 21 had a service of just over 30000ft.


Now,now….let’s not have the truth getting in the way of an expressed opinion.

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## pbehn (Jun 29, 2021)

The Spitfire Mk VI


P-39 Expert said:


> I just have a hard time believing those accounts. With the altitude statistics of the day. A FW190 of 1943 (three years after the BoB) had a combat ceiling (climb 1000fpm) of 8000meters (26400ft). And you're telling me Spitfire I and 109E in 1940 routinely got over 30000ft? The LW bombers came in well under 20000ft. Why in the world would anyone try to get to 30000ft? Like the famous Darwin Australia raids that reportedly came in at 30000ft, none of the aircraft involved had combat ceilings (or for the bombers even service ceilings) even close to that.
> 
> Now maybe once in a blue moon, but routinely why would any of the fighters fly higher than even 5000ft above the bombers? It was possible but highly improbable especially on a routine basis. These were personal accounts, amounting to heresay. Maybe they read their instruments incorrectly, or they were embellishing their story. I don't know. But the equipment involved just wouldn't do that. I cringe when I hear 30000ft in WWII, unless they were escorting B-17/24s and then they were still well under 30000ft. Just my opinion.


Whatever your "combat ceiling" of 1,000ft/min or other was stated as, if you are sent to intercept something you dont radio back, "this is above my rated service ceiling", the two sides were testing each other out and at 30,000ft were hanging on their wings, that's why they frequently just looked at each other. I really dont care what you have a hard time with any more, it is stated in historical records, pilots accounts and respected books on the topic, you can cringe all you like, you are WRONG.


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## Shortround6 (Jun 29, 2021)

P-39 Expert said:


> Trying to supply three different ammo types was insane. Especially when the .30s had an effective range of only 200yds (AHT).


Yep, real insanity, considering that the .30 cal ammo was used by the ground army tripod mounted Browning machine guns, both air and water cooled, the BAR, the M1 Garand, the 1903 Springfield (and variations) and the 1917 Enfield. In 1941 the standard mix of ammo for the ground machine guns was 10%AP, 20% tracer and 70% ball ammo. Getting .30 cal ammo might have been a much smaller problem than getting either 20mm or 37mm ammo. Might not be the preferred types but getting something seems to be pretty easy. 

I would love to see a definition of "effective range" as used in AHT. The max range of a .30 cal Browning with M2 ammunition (150 grain flat based bullet) was about 3,500 yds and the max range using M1 ball (172 grain boat tail) of about 5,500 yds. effective range is certainly much shorter than max range.
However the US Army penetration tables show the M1 ball at 200yds going through an average of 7 in of gravel, 4 in of concrete, 13.8 inches of solid oak, 6.5in of dry sand. These are average penetrations, individual shots sometimes penetrated more. 
I doubt the duralumin skin of most single engine planes is going to stop the .30 bullet. 

A different table for the older 1906 load which was just about identical to the M2 ball ammo claims to would completely penetrate 1/4 low grade steel plate at 400yds. Low grade steel is not armor but then, depending on the angle of impact and deflection caused by the aircraft skin most aircraft structure and engine/cylinder blocks are not going to withstand that force of impact most of the time. 

All penetrations are pretty much sea level and would improve at higher altitudes. 

Not saying that the .30 cal (or .303) was anywhere near as effective as the .50 cal but the idea that the .30 cal bullets cannot inflict damage or are useless at anything beyond 200yds needs to go away and stay away.

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## Milosh (Jun 29, 2021)

buffnut453 said:


> Now,now….let’s not have the truth getting in the way of an expressed opinion.


I guess Expert doesn't know about the interception of HIGH flying German recon airplanes by Spitfires.


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## pbehn (Jun 29, 2021)

Milosh said:


> I guess Expert doesn't know about the interception of HIGH flying German recon airplanes by Spitfires.


Or the recon planes carrying bombs which would be called bombers to the people who had the bombs dropped on them. In fact there were also high and low altitude Jabo raids throughout the BoB but they weren't part of the main story and weren't decisive so get little attention, the fact is they happened and were an issue for Park to deal with, as they were supposed to be.

Even the potted history of Battle of Britain, 10 July-31 October 1940 says this.
*Phase 5 - 1-31 October*

The final stage of the Battle of Britain saw the Germans abandon large scale daylight raids. Instead they focused on small-scale low level raids by Ju 88s and high-level fighter bomber raids, using bomb-carrying Bf 109s supported by pure fighters.


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## Shortround6 (Jun 29, 2021)

P-39 Expert said:


> Why in the world would anyone try to get to 30000ft? Like the famous Darwin Australia raids that reportedly came in at 30000ft, none of the aircraft involved had combat ceilings (or for the bombers even service ceilings) even close to that.
> Now maybe once in a blue moon, but routinely why would any of the fighters fly higher than even 5000ft above the bombers? It was possible but highly improbable especially on a routine basis.



You are confusing combat ceiling and service ceiling, you are also leaving out operational ceiling (climb is 500fpm). It was not uncommon for the British and German fighters to fly at around 30,000ft in the BoB. Not uncommon does not mean common or standard practice, it just means not uncommon. 
The reason is at much over 20,000ft the fighters that had the altitude advantage had a major combat advantage. They did *NOT FIGHT at 30,000ft *but the planes with the altitude advantage could break contact/refuse combat easier. They could trade their altitude for speed (energy) by diving down on their opponents. They could keep going (boom and zoom) and since they were already flying faster in their dives (even if shallow) they were harder for the lower starting altitude fighters to follow. If the diving planes decided to turn they had more speed to burn in the turn before their airspeed fell too low. 
For the British, if you know that some of the German fighters are coming in at around 30,000ft (certainly not all) do you just say "Oh well, we will continue to fly at 24-26,000ft and let them bounce us on occasion" or do you try to get some (not all) of your fighters up to 30,000ft to equal the high flying Germans and/or bounce the Germans that come in at 25,000ft or so? 
A major part of the rational behind the Hurricane II with the Merlin XX engine (deliveries started in Sept 1940) was to improve it's altitude performance, They figured the Merlin XX engine would change the operational ceiling (500fpm climb) from 31,400ft to 34,900ft, They figured this would keep the Hurricane competitive with the 109. 

BTW, the bomber ceilings are often given at full load. For some of the early twin engine bombers burning off several thousand pounds of fuel can change their ceilings by a few thousand feet. You are the one who keeps telling us that just cutting a few hundred pounds out of the P-39 will add hundreds of fpm to it's climb rate and thousands of feet to it's ceiling.

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## Juha3 (Jun 29, 2021)

P-39 Expert said:


> Only difference between air combat in western Europe and eastern Europe was there were no high altitude bombers in Eastern Europe. And those weren't really a force in the west until mid '43. Soviets standard combat formation was the "Kuban Stairs" or "Flying Bookshelves" with a flight (4 planes) at 5000meters (16500ft), a flight at 6000meters (20000ft) and the top flight at 7000meters (23000ft). P-39s could match the LW fighters up to 8000meters (26400ft) with neither side willing to go much higher than that.
> 
> Turbocharged B-17s and B-24s flew at 25000ft with their escorts a little higher. Not much difference.


Where you got the idea that "_P-39s could match the LW fighters up to 8000meters (26400ft_)" maybe even up to 17500 ft but after that P-39 N /Q began to run out of steam.


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## Juha3 (Jun 29, 2021)

P-39 Expert said:


> ...The Soviets configured the P-39 without the .30cal wing guns and they thought it was a really good aircraft. Their favorite.


Soviet removed 7.62 mm mgs pat of their P-39s but not from all, see my message XP-39 II - The Groundhog Day Thread, in June 44 clearly part of the P-39s of the famous 16 GvIAP still had their 7.62 mm mgs installed and loaded. That message was written over ½ year ago but for no good, it seems.

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## buffnut453 (Jun 29, 2021)

P-39 Expert said:


> I just have a hard time believing those accounts. With the altitude statistics of the day. A FW190 of 1943 (three years after the BoB) had a combat ceiling (climb 1000fpm) of 8000meters (26400ft). And you're telling me Spitfire I and 109E in 1940 routinely got over 30000ft? The LW bombers came in well under 20000ft. Why in the world would anyone try to get to 30000ft? Like the famous Darwin Australia raids that reportedly came in at 30000ft, none of the aircraft involved had combat ceilings (or for the bombers even service ceilings) even close to that.
> 
> Now maybe once in a blue moon, but routinely why would any of the fighters fly higher than even 5000ft above the bombers? It was possible but highly improbable especially on a routine basis. These were personal accounts, amounting to heresay. Maybe they read their instruments incorrectly, or they were embellishing their story. I don't know. But the equipment involved just wouldn't do that. I cringe when I hear 30000ft in WWII, unless they were escorting B-17/24s and then they were still well under 30000ft. Just my opinion.



Well, since you've frequently quoted WW2aircraftperformance.org (Source: http://www.wwiiaircraftperformance.org/wade-ceiling.jpg), perhaps this table may help change your mind. It was originally published in _The Aeroplane _on 21 June 1946. Yes the Spitfire variants are much later than the MkI of BoB....but it would be a phenomenal increase to take an aircraft that, in 1940, couldn't best 25,000ft and then, just a few years later, attain 37,000ft (or thereabouts)...it's a big enough increase to go from 30K to 37K.







Can't you, for once, admit you are wrong about something? You're expressing an opinion and yet seem to be entirely unmoved by any evidence to the contrary. Again, you wonder why we call this the groundhog day thread.


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## 33k in the air (Jun 29, 2021)

Need I point out the P-39's small internal fuel load which limits its operational radius considerably? In the second half of 1943 the USAAF is rapidly realizing range is a vital component, and that's something the P-39 simply cannot supply.

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## buffnut453 (Jun 29, 2021)

P-39 Expert said:


> These were personal accounts, amounting to heresay. Maybe they read their instruments incorrectly, or they were embellishing their story. I don't know.



Sorry but these comments are just a bullshit excuse to avoid factual data that directly contradicts your "opinion." One of the quoted items was not a "personal account". It was an official post-mission report. Are you telling me that, straight after this sortie, Eric Thomas lied to say he was flying higher than he actually was? Are you also suggesting that his entire squadron, that he was leading on this mission, was in on the embellishment? Come on, that really is ridiculous. 

Are you also suggesting that Alfred Price is lying when he cites the service ceiling of the Spitfire MkI as being in excess of 34,000ft?

Please just admit you are mistaken and maybe, for once, we can move on.

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## wuzak (Jun 29, 2021)

Here is a report of a Spitfire I





Spitfire Mk I K.9787 Trials Report


Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.



www.spitfireperformance.com





In the climbing trials it estimates an absolute ceiling of 32,800ft, the service ceiling (climb 100ft/min) was 31,900ft and the maximum altitude reached on test was 32,400ft. 

Time to climb to 30,000ft was 22.4 minutes.

The maximum speed at 30,000ft was 315mph. 

Test was in January 1939. The engine fitted was a Merlin II, and the prop was wooden, fixed pitch.


With Merlin III and 2 pitch metal prop the estimated service ceiling was above 35,000ft. Time to climb to 30,000ft had gone up by a minute or so.





Spitfire Mk I L.1007 Trials Report


Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.



www.spitfireperformance.com





That was July 1939.


With Merlin III and constant speed prop, as tested in March 1940.





Spitfire Mk I N.3171 Trials Report


Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.



www.spitfireperformance.com





Speed at 30,000ft was up marginally to 319mph TAS, time to 30,000ft was down to 16.1 minutes. Service ceiling 35,800ft. Rate of climb was 660ft/minute.

This aircraft was 230lb heavier than the on in the first listed report.



With 2 20mm cannon and 4 0.303" mgs, weighing 300lb more than the previous example, this Spitfire I climbed to 30,000ft in 19.6 minutes, had an estimated service ceiling of 34,700ft and a climb of 570ft/min at 30,000ft.



http://www.spitfireperformance.com/Spitfire_IB_K4257_R6770_Summary_of_Trials.jpg



Report dated 19 February 1941.

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## buffnut453 (Jun 29, 2021)

wuzak said:


> Here is a report of a Spitfire I
> 
> 
> 
> ...



Brilliant stuff, Wuzak...I was hoping someone would have actual test figures for the Spit MkI. Thanks for posting these details. 

Just to add to the evidence pile, the service ceiling for the Bf109E-3 was 11,000m or 36,089ft. "Die Dienstgipfelhöhe beträgt bei voller Ausrüstung 11 000 m." (Source: Kurfürst - Baubeschreibung für das Flugzeugmuster Messerschmitt Me 109 mit DB 601.)

Also, the service ceiling for the Bf110C-4 was 10,000m or 32,808ft (Source: Lexikon der Wehrmacht - Messerschmitt Bf 110)

So...anyone found any contradictory sources that put the service ceiling for these types at around 25,000ft?


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## ThomasP (Jun 29, 2021)

To be fair, P-39 Expert said "Spitfire and 109E combat ceilings (1000fpm climb) were a little above 25000'. 110s about 21000ft." in his post#1,907 - not service ceiling.

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## wuzak (Jun 29, 2021)

He is referring to "combat ceiling", which he is saying is 1,000ft/min. I don't know if that is an official number or where he got that from.

For the P-39C that was slightly below 25,000ft. For the P-39D that was ~23,000ft.

For the Spitfire I of early 1940 that was ~27,000ft.






Spitfire Mk I N.3171 Trials Report


Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.



www.spitfireperformance.com





For the Spitfire V, with 2 x 20mm cannon, 4 x 0.303"mgs the 1,000ft/min climb was met at around 31,200ft.

The Spitfire V being more contemporary with the P-39C and D than the I.

The Spitfire tests were done by the A&AEE.

The early P39 tests look to have been done by the USAAC/F Materiel Command, but test of the later models start with "Report on flight tests of Bell P-39 airplane at the manufacturer's plant". Which begs the question, are those manufacturer's performance numbers, or performance tested by the air force?


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## buffnut453 (Jun 29, 2021)

ThomasP said:


> To be fair, P-39 Expert said "Spitfire and 109E combat ceilings (1000fpm climb) were a little above 25000'. 110s about 21000ft." in his post#1,907 - not service ceiling.



Yes, but it was in the context of his opinion that combat at 30,000ft being impossible in the BoB. Plenty of data has been provided to show that it was, indeed, possible and yet he refuses to accept it and ploughs forward with his "opinion".


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## ThomasP (Jun 29, 2021)

re Combat and Operational ceiling

"P-39C-D & 400"


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## Shortround6 (Jun 29, 2021)

Sorry guys, lost some of the text.


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## Shortround6 (Jun 29, 2021)

P-39 Expert said:


> a fuel powered cabin heater (when heating/cooling of the cabin was actually already very good)



You might be interested to know that the heating of the cabin of the P-39C and D was very good because they used a Stewart-Warner gasoline type heater.

This is stated in the pilots manuals. 

So, NO, the British did NOT load the plane down with useless stuff like a fuel powered heater, it was already there.

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## DerAdlerIstGelandet (Jun 30, 2021)

62 more posts and we hit 2000 posts! 3 more pages to 100!

Milestones of groundhogism.

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## GrauGeist (Jun 30, 2021)

Greg Boeser said:


> Re: .30 caliber MGs
> USAAF aircraft equipped with this weapon at the end of 1941
> P-26
> P35A
> ...


The P-43 was equipped with four .50MGs prior to 1941.


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## Greg Boeser (Jun 30, 2021)

That's why it didn't make the list. Plus, it didn't see action with the USAAF. Wait, AVG/ 23rd FG had a few.
P-26 shouldn't be included either. They were assigned to the Philippine Air Force.


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## pbehn (Jun 30, 2021)

Juha3 said:


> Soviet removed 7.62 mm mgs pat of their P-39s but not from all, see my message XP-39 II - The Groundhog Day Thread, in June 44 clearly part of the P-39s of the famous 16 GvIAP still had their 7.62 mm mgs installed and loaded. That message was written over ½ year ago but for no good, it seems.


This is a requirement of groundhogism. A point of view is never disproved by facts, after a few months rest it can be brought back again. It cannot be accepted that any combat took place in the BoB at 30,000ft because that would undermine the argument that the British rejected the P-39 (and P-40) for UK based operations because of performance not cost and spite.

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## P-39 Expert (Jun 30, 2021)

Some of you guys (not all) need to understand the difference between service ceiling and combat ceiling. WW2 fighters very seldom got anywhere near their service ceiling when the plane climbed at only 100fpm. Mainly theoretical, this figure wasn't normally reached even during official tests. It was projected based on climb tests at lower altitudes. In test conditions, not in combat. I believe the British started the term combat ceiling which is the altitude at which a plane will no longer climb at 1000fpm. That's about as high as a fighter will want to go in combat. Climb is at or near full power at around 150-175mph IAS. Crawling up to 30000ft at that speed is hazardous to one's health in combat. And hard on the engine to be at full power for that long.

I never said nobody ever got to 30000ft in the BoB, just that it was extremely uncommon. And like victory claims, probably not that accurate. Just my opinion.

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## P-39 Expert (Jun 30, 2021)

Shortround6 said:


> You might be interested to know that the heating of the cabin of the P-39C and D was very good because they used a Stewart-Warner gasoline type heater.
> 
> This is stated in the pilots manuals.
> 
> So, NO, the British did NOT load the plane down with useless stuff like a fuel powered heater, it was already there.


Would like to see those pilot manuals. All the information I have ever seen shows heated air ducted from the coolant radiator exhaust up to the cabin. Rated as very efficient cabin heat in Eglin Field tests. The P-400 used the fuel powered heater, I have seen that manual. That fuel powered heater may have been efficient but it caused radio static feedback, making either the heater or the radio unusable.


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## pbehn (Jun 30, 2021)

P-39 Expert said:


> Some of you guys (not all) need to understand the difference between service ceiling and combat ceiling. WW2 fighters very seldom got anywhere near their service ceiling when the plane climbed at only 100fpm. Mainly theoretical, this figure wasn't normally reached even during official tests. It was projected based on climb tests at lower altitudes. In test conditions, not in combat. I believe the British started the term combat ceiling which is the altitude at which a plane will no longer climb at 1000fpm. That's about as high as a fighter will want to go in combat. Climb is at or near full power at around 150-175mph IAS. Crawling up to 30000ft at that speed is hazardous to one's health in combat. And hard on the engine to be at full power for that long.
> 
> I never said nobody ever got to 30000ft in the BoB, just that it was extremely uncommon. And like victory claims, probably not that accurate. Just my opinion.


And you need to understand that it makes no difference what you call the ceiling. The LW sent recon planes over UK at extremely high altitude dropping bombs, eventually a modified Spitfire shot one down at 42,000 ft. One gun was jammed and every time the other fired the plane stalled and dropped. After several attempts it made one hit with a cannon shell, that was enough to stop that type of raid. That is what it was all about, it doesnt have to be "common" it would have persisted until a successful interception happened. This is what happened in the dog days of the BoB, what began as a free shot, dropping bombs randomly on Kent and London started to cost pilots and planes and so was stopped. Can you remind us what you said makes you cringe?

Here you are, my bold.
Quote "*BoB got nowhere near 30000ft*. Spitfire and 109E combat ceilings (1000fpm climb) were a little above 25000'. 110s about 21000ft. He111 ABSOLUTE ceiling was 22000ft. *Nobody going near 30000ft*, much less over except possibly recon missions. *I cringe when I hear 30000ft in WWII.*


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## buffnut453 (Jun 30, 2021)

P-39 Expert said:


> Some of you guys (not all) need to understand the difference between service ceiling and combat ceiling. WW2 fighters very seldom got anywhere near their service ceiling when the plane climbed at only 100fpm. Mainly theoretical, this figure wasn't normally reached even during official tests. It was projected based on climb tests at lower altitudes. In test conditions, not in combat. I believe the British started the term combat ceiling which is the altitude at which a plane will no longer climb at 1000fpm. That's about as high as a fighter will want to go in combat. Climb is at or near full power at around 150-175mph IAS. Crawling up to 30000ft at that speed is hazardous to one's health in combat. And hard on the engine to be at full power for that long.
> 
> I never said nobody ever got to 30000ft in the BoB, just that it was extremely uncommon. And like victory claims, probably not that accurate. Just my opinion.



We understand the difference. 

As to your last statement, you're now trying to duck out of your incorrect statement without admitting you were wrong. You explicitly stated "BoB got nowhere near 30000ft." That's a pretty definitive statement. "Nowhere near" is not the same as "extremely uncommon."

You've been presented with actual pilot manuals citing that the Spitfire MkI and the Messerschmitt Bf109E-3 could get above 30,000ft. You have a contemporary account of a Spitfire pilot leading his squadron at 30,000ft and engaging Bf109s. And yet you persist that these data points are somehow not accurate? 

Please provide data that you think is more accurate.

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## P-39 Expert (Jun 30, 2021)

buffnut453 said:


> Well, since you've frequently quoted WW2aircraftperformance.org (Source: http://www.wwiiaircraftperformance.org/wade-ceiling.jpg), perhaps this table may help change your mind. It was originally published in _The Aeroplane _on 21 June 1946. Yes the Spitfire variants are much later than the MkI of BoB....but it would be a phenomenal increase to take an aircraft that, in 1940, couldn't best 25,000ft and then, just a few years later, attain 37,000ft (or thereabouts)...it's a big enough increase to go from 30K to 37K.
> 
> View attachment 630448
> 
> ...


Depends on how the magazine defined operational ceiling. Was it service ceiling, combat ceiling, or something else. And all those planes came well after the BoB with ceilings well above the Spit I and 109E. And it was a magazine, not an official test.


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## buffnut453 (Jun 30, 2021)

P-39 Expert said:


> Depends on how the magazine defined operational ceiling. Was it service ceiling, combat ceiling, or something else. And all those planes came well after the BoB with ceilings well above the Spit I and 109E. And it was a magazine, not an official test.



So what about all the other data that's been presented related to Spitfire MkI and Bf109E-3. Are you going to ignore that as well?


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## Shortround6 (Jun 30, 2021)

P-39 Expert said:


> Some of you guys (not all) need to understand the difference between service ceiling and combat ceiling.


Some people need to understand that there was also a 3rd ceiling, operational ceiling which was 500fpm, this was considered the climb rate needed for a small group of planes to maintain formation. The 109, Hurricane I and Spitifire I with constant speed props all had operational ceilings of over 30,000ft. 
Source "The Merlin in Perspective-the combat years" 4th edition Rolls Royce Heritage trust. In Appendix V. 


P-39 Expert said:


> That's about as high as a fighter will want to go in combat.


There is also a difference between "combat" as in actual maneuver fighting and a combat patrol or flight in which the goal is to be above the enemy so they can use the advantage of height. The actual "combat" (firing of guns) may take place several thousand feet lower. Being the one's getting bounced from above was known not to be a good thing by about 1916  


P-39 Expert said:


> Would like to see those pilot manuals.


Try BELL P-39 AIRACOBRA - Flight Manuals

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## pbehn (Jun 30, 2021)

P-39 Expert said:


> Depends on how the magazine defined operational ceiling. Was it service ceiling, combat ceiling, or something else. And all those planes came well after the BoB with ceilings well above the Spit I and 109E. And it was a magazine, not an official test.


The important altitude is the altitude of the enemy aircraft coming into your space. Discussion of terms is just a distraction, as you know, that is why you are doing it.


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## P-39 Expert (Jun 30, 2021)

Juha3 said:


> Where you got the idea that "_P-39s could match the LW fighters up to 8000meters (26400ft_)" maybe even up to 17500 ft but after that P-39 N /Q began to run out of steam.


Conversations with N. Golodnikov, Part 3, P-39. Conversations with N.Golodnikov. Part Three. P-39 Airacobra and Yaks – Lend-Lease


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## P-39 Expert (Jun 30, 2021)

Shortround6 said:


> You are confusing combat ceiling and service ceiling, you are also leaving out operational ceiling (climb is 500fpm). It was not uncommon for the British and German fighters to fly at around 30,000ft in the BoB. Not uncommon does not mean common or standard practice, it just means not uncommon.
> The reason is at much over 20,000ft the fighters that had the altitude advantage had a major combat advantage. They did *NOT FIGHT at 30,000ft *but the planes with the altitude advantage could break contact/refuse combat easier. They could trade their altitude for speed (energy) by diving down on their opponents. They could keep going (boom and zoom) and since they were already flying faster in their dives (even if shallow) they were harder for the lower starting altitude fighters to follow. If the diving planes decided to turn they had more speed to burn in the turn before their airspeed fell too low.
> For the British, if you know that some of the German fighters are coming in at around 30,000ft (certainly not all) do you just say "Oh well, we will continue to fly at 24-26,000ft and let them bounce us on occasion" or do you try to get some (not all) of your fighters up to 30,000ft to equal the high flying Germans and/or bounce the Germans that come in at 25,000ft or so?
> A major part of the rational behind the Hurricane II with the Merlin XX engine (deliveries started in Sept 1940) was to improve it's altitude performance, They figured the Merlin XX engine would change the operational ceiling (500fpm climb) from 31,400ft to 34,900ft, They figured this would keep the Hurricane competitive with the 109.
> ...


Not uncommon? But they did *not fight at 30,000ft? *Okay, whatever you say. I just believe that in the BoB planes actually getting to 30000' is extremely rare, which I would define as a lot less than not uncommon. Extremely rare does not mean never. My opinion.

And I am not confusing combat ceiling with operational ceiling. I almost always reference combat ceiling as climb at 1000fpm.


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## wuzak (Jun 30, 2021)

P-39 Expert said:


> Some of you guys (not all) need to understand the difference between service ceiling and combat ceiling. WW2 fighters very seldom got anywhere near their service ceiling when the plane climbed at only 100fpm. Mainly theoretical, this figure wasn't normally reached even during official tests. It was projected based on climb tests at lower altitudes.



From Spitfire Mk I K.9787 Trials Report

`alt (ft) time (min) RoC (ft/min)
23,000 11.7 1135
26,000 14.8 790
28,000 17.8 555
30,000 22.4 325
32,000 32.9 95`

Estimated absolute ceiling: 32,800ft
Greatest height reached: 32,400ft

That was with a fixed pitch wooden propeller (2 blade?).

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## Shortround6 (Jun 30, 2021)

Both sides in 1940-41 were working to improve the ceilings (all of them by whatever name) of their aircraft because it takes months if not years to get to get a new airplane or engine into service (variations of existing equipment takes less time but not instant), You can't wait for your opponent to_ show _his improved capability. You have to be working on improving your own so you are ready when his improvement/s show up.
Reason for the Hurricane II was to improve the Hurricane so it was close to the Spitfire in capability so the total number of fighters being produced were altitude capable, making Spitfires with Merlin XX engines and continuing to make Hurricanes with Melrin IIIs or Melrin XIIs would have meant an overall less capable fighter force. 
A wrench in the works was that cockpit heating, gun heating and oxygen equipment did not progress as fast as the engines so the engine improvements were harder to take advantage of. 
The P-400/P-39 showed up at the wrong time. It showed up as the British were anticipating higher operational ceilings and the British were already getting low altitude P-40s and about to get low altitude Mustang Is. 
In Mid 1941 to spring of 1942 the Bell fighter simply doesn't bring much to the table as production versions are much slower than promised and they can't do anything that can't be done by a number of fighters already in British service except complicate the supply situation.


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## P-39 Expert (Jun 30, 2021)

Shortround6 said:


> Yep, real insanity, considering that the .30 cal ammo was used by the ground army tripod mounted Browning machine guns, both air and water cooled, the BAR, the M1 Garand, the 1903 Springfield (and variations) and the 1917 Enfield. In 1941 the standard mix of ammo for the ground machine guns was 10%AP, 20% tracer and 70% ball ammo. Getting .30 cal ammo might have been a much smaller problem than getting either 20mm or 37mm ammo. Might not be the preferred types but getting something seems to be pretty easy.
> 
> I would love to see a definition of "effective range" as used in AHT. The max range of a .30 cal Browning with M2 ammunition (150 grain flat based bullet) was about 3,500 yds and the max range using M1 ball (172 grain boat tail) of about 5,500 yds. effective range is certainly much shorter than max range.
> However the US Army penetration tables show the M1 ball at 200yds going through an average of 7 in of gravel, 4 in of concrete, 13.8 inches of solid oak, 6.5in of dry sand. These are average penetrations, individual shots sometimes penetrated more.
> ...


AHT lists the 30calMG to have an effective range of 200yds in their gun table and talks about it in the text. 

Yes there were lots of .30cal rounds available, since it was a standard round for the infantry. Are you advocating converting all seven guns in the P-39 to the .30cal? That makes about as much sense as your argument.

The .30cal MG was phased out of AAF/USN use before Pearl Harbor for all the American fighters except the P-39. I'm advocating it should have been phased out of the P-39 also.


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## wuzak (Jun 30, 2021)

P-39 Expert said:


> The .30cal MG was phased out of AAF/USN use before Pearl Harbor for all the American fighters except the P-39. I'm advocating it should have been phased out of the P-39 also.



Um, the P-40s at Pearl Harbor _were _fitted with the 0.30"mg.

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## Shortround6 (Jun 30, 2021)

P-39 Expert said:


> Yes there were lots of .30cal rounds available, since it was a standard round for the infantry. Are you advocating converting all seven guns in the P-39 to the .30cal? That makes about as much sense as your argument.


Never said that did I?

Just saying that keeping the .30 cal was not the logistics problem you are making it out to be. 

Now why don't you give the rest of the information in the tables and btw, the text includes NO definition of either "max effective practical range" or "max effective theoretical range"
For the .30 cal these ranges are the 200 yds you have said and 600yds, the 37mm cannon had ranges of 300yds and 600yds. The 50 cal has ranges of 300yds and 900 yds while the 20mm in the table has ranges of 1200 yds and 2400yds which is total nonsense. 

I would also note that the heavier weight given for the 30 cal bullets like 220 grains is total nonsense. The US stopped putting 220 grain projectiles into 30 cal rifle ammo in 1906 when they changed from the .30-03 round to the .30-06. The .30-03 won't even chamber in a .30-06 gun. 

AHT is very, very good. It is not infallible. 

Have to go to work now.

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## pbehn (Jun 30, 2021)

P-39 Expert said:


> Not uncommon? But they did *not fight at 30,000ft? *Okay, whatever you say. I just believe that in the BoB planes actually getting to 30000' is extremely rare, which I would define as a lot less than not uncommon. Extremely rare does not mean never. My opinion.
> 
> And I am not confusing combat ceiling with operational ceiling. I almost always reference combat ceiling as climb at 1000fpm.


Are you saying that a plane shot down at 30,000ft was not actually in combat because it was above the "combat" altitude? What do you call firing guns at each other, other than fight or combat? This is taking groundhogism to a new height, or dare I say a new altitude of semantics.


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## glennasher (Jun 30, 2021)

We might as well take a trip to Yosemite NP and try to educate El Capitan, it would be easier than trying to educate the "Expert".

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## buffnut453 (Jun 30, 2021)

P-39 Expert said:


> The .30cal MG was phased out of AAF/USN use before Pearl Harbor for all the American fighters except the P-39. I'm advocating it should have been phased out of the P-39 also.



As others have pointed out, the e0cal was still in use in P-40s at Pearl Harbor.

Also the 30cal was REPLACED with the 50 cal. So to match other US fighters, you'd have to do the same. How will that affect the weight of your P-39 wonder-weapon?


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## Peter Gunn (Jun 30, 2021)

Uhh... are you saying now that the P-39 was able to do the Mustang's job? And is it supposed to match the Mustang's performance at 26,400 feet? Which is basically RIGHT in the Mustang's wheelhouse.



P-39 Expert said:


> Only difference between air combat in western Europe and eastern Europe was there were no high altitude bombers in Eastern Europe. And those weren't really a force in the west until mid '43. Soviets standard combat formation was the "Kuban Stairs" or "Flying Bookshelves" with a flight (4 planes) at 5000meters (16500ft), a flight at 6000meters (20000ft) and the top flight at 7000meters (23000ft). *P-39s could match the LW fighters up to 8000meters (26400ft) with neither side willing to go much higher than that.
> 
> Turbocharged B-17s and B-24s flew at 25000ft with their escorts a little higher. Not much difference.*


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## wuzak (Jun 30, 2021)

P-39 Expert said:


> Turbocharged B-17s and B-24s flew at 25000ft with their escorts a little higher. Not much difference.


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## Juha3 (Jun 30, 2021)

P-39 Expert said:


> Conversations with N. Golodnikov, Part 3, P-39. Conversations with N.Golodnikov. Part Three. P-39 Airacobra and Yaks – Lend-Lease



I read the article soon after it was published, it is interesting but not error free, and he said that " 8,000 meters without problem, and neither we nor the Germans flew higher than that." not that P-39 _could match the LW fighters up to 8000meters. _His claim might be correct up north but as I wrote earlier, e.g. in Leningrad area, both P-39s and German recon planes flew at least at 9000 m, two P-39s and two La-5s ( giving the date probably La-5FNs but Soviets usually reported all La-5 versions simply as La-5) intercepted a Ju 88S at 9000 m on 8 March 1945. Ju 88S were easily capable to fly even higher than that. As I said, I saw the article interesting even if there was not very much new to me, Finns fought against P-39s of the Karelian Front and Leningrad PVO, I have even talked with at least a couple of the FiAF aces who had had combats with P-39s. We have been well aware over 75 years that VVS used their P-39s as air superiority fighters and interceptors.


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## P-39 Expert (Jun 30, 2021)

Shortround6 said:


> Never said that did I?
> 
> Just saying that keeping the .30 cal was not the logistics problem you are making it out to be.
> 
> ...


Where did you see the 600yds range for the .30cal? Edit: Oh, sorry, I see it now. AHT lists 200yds as the max practical range. Why would we want the max theoretical range?


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## P-39 Expert (Jun 30, 2021)

pbehn said:


> Are you saying that a plane shot down at 30,000ft was not actually in combat because it was above the "combat" altitude? What do you call firing guns at each other, other than fight or combat? This is taking groundhogism to a new height, or dare I say a new altitude of semantics.


You know full well that I was replying to Shortround's post where he said that altitudes of 30000' in the BoB were not uncommon but *they did not fight at 30000' (bold is his). *I never said that a plane shot down at 30000' was not in combat. 

I also never said that no planes got up to 30000' in the BoB. Shortround said it was not uncommon. I say it was very rare. If not almost never.


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## P-39 Expert (Jun 30, 2021)

Peter Gunn said:


> Uhh... are you saying now that the P-39 was able to do the Mustang's job? And is it supposed to match the Mustang's performance at 26,400 feet? Which is basically RIGHT in the Mustang's wheelhouse.


Stop putting words in my mouth. I have never said that the P-39 was able to do the Mustang's job. I have said that P-39s could have escorted B-17/24s in Europe, certainly not as far or as well.


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## pbehn (Jun 30, 2021)

P-39 Expert said:


> You know full well that I was replying to Shortround's post where he said that altitudes of 30000' in the BoB were not uncommon but *they did not fight at 30000' (bold is his). *I never said that a plane shot down at 30000' was not in combat.
> 
> I also never said that no planes got up to 30000' in the BoB. Shortround said it was not uncommon. I say it was very rare. If not almost never.


It was so common it became an issue that Park and the RAF had to address, can you read a book on it instead of just giving us your feelings?


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## P-39 Expert (Jun 30, 2021)

wuzak said:


> Um, the P-40s at Pearl Harbor _were _fitted with the 0.30"mg.


Okay, how many P-40s with .30calMGs served in the AAF after Pearl Harbor?


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## P-39 Expert (Jun 30, 2021)

Shortround6 said:


> Both sides in 1940-41 were working to improve the ceilings (all of them by whatever name) of their aircraft because it takes months if not years to get to get a new airplane or engine into service (variations of existing equipment takes less time but not instant), You can't wait for your opponent to_ show _his improved capability. You have to be working on improving your own so you are ready when his improvement/s show up.
> Reason for the Hurricane II was to improve the Hurricane so it was close to the Spitfire in capability so the total number of fighters being produced were altitude capable, making Spitfires with Merlin XX engines and continuing to make Hurricanes with Melrin IIIs or Melrin XIIs would have meant an overall less capable fighter force.
> A wrench in the works was that cockpit heating, gun heating and oxygen equipment did not progress as fast as the engines so the engine improvements were harder to take advantage of.
> The P-400/P-39 showed up at the wrong time. It showed up as the British were anticipating higher operational ceilings and the British were already getting low altitude P-40s and about to get low altitude Mustang Is.
> In Mid 1941 to spring of 1942 the Bell fighter simply doesn't bring much to the table as production versions are much slower than promised and they can't do anything that can't be done by a number of fighters already in British service except complicate the supply situation.


No 7850lb fighter with an 1150hp engine will bring much to the table. A 7100lb fighter will bring a lot to the table.


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## Glider (Jun 30, 2021)

P-39 Expert said:


> No 7850lb fighter with an 1150hp engine will bring much to the table. A 7100lb fighter will bring a lot to the table.


But not for very long before it becomes a statistic


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## P-39 Expert (Jun 30, 2021)

pbehn said:


> And you need to understand that it makes no difference what you call the ceiling. The LW sent recon planes over UK at extremely high altitude dropping bombs, eventually a modified Spitfire shot one down at 42,000 ft. One gun was jammed and every time the other fired the plane stalled and dropped. After several attempts it made one hit with a cannon shell, that was enough to stop that type of raid. That is what it was all about, it doesnt have to be "common" it would have persisted until a successful interception happened. This is what happened in the dog days of the BoB, what began as a free shot, dropping bombs randomly on Kent and London started to cost pilots and planes and so was stopped. Can you remind us what you said makes you cringe?
> 
> Here you are, my bold.
> Quote "*BoB got nowhere near 30000ft*. Spitfire and 109E combat ceilings (1000fpm climb) were a little above 25000'. 110s about 21000ft. He111 ABSOLUTE ceiling was 22000ft. *Nobody going near 30000ft*, much less over except possibly recon missions. *I cringe when I hear 30000ft in WWII.*


Every one of you guys are masters at taking a general statement and finding a very small number of exceptions and then stating that I'm wrong. It was a big war with lots of exceptions to every rule.

I'll stick with cringing whenever I hear 30000' in the BoB. I still don't believe it was even an everyday occurrence. Just because you found a very few examples of somebody claiming to get to 30000' does not mean it was common. You know it was not. To get to 30000' a Spitfire would be climbing at around 500fpm. That is a vertical speed of a little over 5mph, a little better than walking speed. 

Bombers in the Bob are certainly not getting to 30000', more like under 20000'. The goal of the British in the BoB was to shoot down bombers, not fighters. Why would they be drawn away from their main target (bombers) to go chase some 109Es? Sure, send an element, maybe a flight (4) up to harass them, but the main force of interceptors will be heading for the bombers.


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## pbehn (Jun 30, 2021)

P-39 Expert said:


> Every one of you guys are masters at taking a general statement and finding a very small number of exceptions and then stating that I'm wrong. It was a big war with lots of exceptions to every rule.
> 
> I'll stick with cringing whenever I hear 30000' in the BoB. I still don't believe it was even an everyday occurrence. Just because you found a very few examples of somebody claiming to get to 30000' does not mean it was common. You know it was not. To get to 30000' a Spitfire would be climbing at around 500fpm. That is a vertical speed of a little over 5mph, a little better than walking speed.
> 
> Bombers in the Bob are certainly not getting to 30000', more like under 20000'. The goal of the British in the BoB was to shoot down bombers, not fighters. Why would they be drawn away from their main target (bombers) to go chase some 109Es? Sure, send an element, maybe a flight (4) up to harass them, but the main force of interceptors will be heading for the bombers.


It was the issue that had to be solved in October 1940. If you read in detail the daily reports there were many others before that were ignored because there were bigger fish to fry. The LW would continue them until they were stopped, as they did later with low level tip and run raids, they continued until Typhoons started to chase them down. So just because I read it in a book and quote it, your feelings on the matter become paramount, no wonder this groundhog thread goes on for ever, it is based on your emotions.


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## P-39 Expert (Jun 30, 2021)

pbehn said:


> It was the issue that had to be solved in October 1940. If you read in detail the daily reports there were many others before that were ignored because there were bigger fish to fry. The LW would continue them until they were stopped, as they did later with low level tip and run raids, they continued until Typhoons started to chase them down. So just because I read it in a book and quote it, your feelings on the matter become paramount, no wonder this groundhog thread goes on for ever, it is based on your emotions.


That would hurt my feelings if I had any. I'm about as unemotional on this as can be. Thanks for thinking about me.


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## pbehn (Jun 30, 2021)

P-39 Expert said:


> That would hurt my feelings if I had any. I'm about as unemotional on this as can be. Thanks for thinking about me.


You said it NEVER happened, when shown that it did you opine on frequency and how many you think took place. 
From wiki 
The _Luftwaffe_ decided to expand its fighter bomber force and an additional group equipped with modified Bf 109s became operational in August. On 2 September Hermann Göring, the Commander-in-Chief of the _Luftwaffe_, directed that one squadron of each Bf 109 group was to be equipped with fighter-bombers and that these aircraft were to be used to attack the British aircraft industry and other industrial facilities.[6]​

Despite Göring's directive, only 19 fighter-bomber operations were conducted against the UK during September 1940. These operations involved 428 sorties, of which 264 were conducted against London. Four fighter-bombers were lost, one by fighters and the others to anti-aircraft guns.[7]​ On 26 September, a force of fifty fighter-bombers and medium bombers attacked the Supermarine aircraft factory at Woolston, Southampton; this raid stopped all production at the factory for a period and killed more than thirty people. The Royal Air Force (RAF) shot down three of the raiders but lost six fighters. The next day, ten Bf 110 fighter-bombers escorted by other fighters attempted to attack either RAF Filton or another target near Bristol. This force was intercepted by No. 504 Squadron RAF and the Bf 110s dropped their bombs on Bristol, causing little damage.[8]​

Later in autumn, the _Luftwaffe_ conducted a series of attacks on London using Bf 109 fighter-bombers.[8]​ These operations represented the majority of German attacks on Britain in October 1940, and the British defences had difficulty detecting and intercepting the high-flying and fast fighter-bomber formations. Due to their speed British radar stations usually provided less than 20 minutes warning before the aircraft arrived over London.[9]​ The _Luftwaffe_ conducted 140 attacks involving 2,633 fighter-bomber sorties against London during October. Losses were light, with 29 Bf 109s being destroyed.[10]​ October marked the peak of fighter-bomber operations in 1940 but attacks continued until late in the year. The rate of effort decreased during November and December as the Bf 109s needed to be used to counter RAF fighter sweeps over France and the onset of winter weather reduced flying opportunities.[11]​


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## P-39 Expert (Jun 30, 2021)

pbehn said:


> You said it NEVER happened, when shown that it did you opine on frequency and how many you think took place.
> From wiki
> The _Luftwaffe_ decided to expand its fighter bomber force and an additional group equipped with modified Bf 109s became operational in August. On 2 September Hermann Göring, the Commander-in-Chief of the _Luftwaffe_, directed that one squadron of each Bf 109 group was to be equipped with fighter-bombers and that these aircraft were to be used to attack the British aircraft industry and other industrial facilities.[6]​
> 
> ...


Your point being?


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## pbehn (Jun 30, 2021)

P-39 Expert said:


> Your point being?


2,600 sorties and 29 planes lost doing it in one month is not never and not few or hardly ever, is it? That is my point, what is yours, do you now accept that many sorties took place at high altitude in the BoB? My other point is the P-39 would be utterly useless in countering these raids.


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## P-39 Expert (Jun 30, 2021)

pbehn said:


> 2,600 sorties and 29 planes lost doing it in one month is not never and not few or hardly ever, is it? That is my point, what is yours, do you now accept that many sorties took place at high altitude in the BoB? My other point is the P-39 would be utterly useless in countering these raids.


I didn't see one altitude reference.


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## pbehn (Jun 30, 2021)

P-39 Expert said:


> I didn't see one altitude reference.


In my previous posts and posts by others, you are just trolling, you prove they werent at high altitude because you have been given ample references that say they were. The whole point is that fighters in UK had to reach 30,000ft to do their job, which means the P-39 would be utterly completely absolutely useless, no use at all, devoid of usefulness, do you get my point?


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## P-39 Expert (Jun 30, 2021)

You are totally confused. I have not made one reference to the P-39 in the BoB. P-39 production didn't even start until 1941. There were no P-30s available for the BoB.

You still haven't convinced me of any serious or consistent combat at 30000' in the BoB.

I am not trolling anyone. You are trolling me.


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## pbehn (Jun 30, 2021)

P-39 Expert said:


> You are totally confused. I have not made one reference to the P-39 in the BoB. P-39 production didn't even start until 1941. There were no P-30s available for the BoB.
> 
> You still haven't convinced me of any serious or consistent combat at 30000' in the BoB.
> 
> I am not trolling anyone. You are trolling me.


Where in my post did I mention the BoB, the BoB as an event was over, the RAF still had to defend its airspace which in 1942 meant interceptions at 42,000ft and low level tip and run raiders all along the south coast, again the P-39 would be useless at this, which is why the British sent the malfunctioning rubbish away. I no longer care what you are convinced of because nothing convinces you of anything. What is serious and consistent? Isnt 2,600 in a month serious and consistent? The link if you read it says "and the British defences had difficulty detecting and intercepting the *high-flying* and fast fighter-bomber formations. " 

High flying means high altitude, that is not low or medium but high. 10,000ft isnt high, 20,000ft isnt high 25-30000ft is high.


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## Pursuivant (Jun 30, 2021)

DKoor said:


> I may be 'pushing it' a bit if I say that if the game "IL-2 Sturmovik" is ANYTHING to go by, P-39 was truly fearsome weapon if piloted by a grizzled veteran.



This opens up an entirely different can of worms. I'm an "IL-2 Sturmovik" fan as well, and players have been squabbling about the flight and damage models of the P-39 series since the game was released. While the game developers never revealed the plane's exact game performance, there's good evidence that it was "overmodeled" when the game was released and only partially "nerfed" in later releases.

Even the best simulation can't model real life.

Complicating things is the fact that every plane was slightly different, with small differences in manufacturing standards, materials, condition, and maintenance affecting peak performance.


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## P-39 Expert (Jun 30, 2021)

pbehn said:


> You said it NEVER happened, when shown that it did you opine on frequency and how many you think took place.
> From wiki
> The _Luftwaffe_ decided to expand its fighter bomber force and an additional group equipped with modified Bf 109s became operational in August. On 2 September Hermann Göring, the Commander-in-Chief of the _Luftwaffe_, directed that one squadron of each Bf 109 group was to be equipped with fighter-bombers and that these aircraft were to be used to attack the British aircraft industry and other industrial facilities.[6]​
> 
> ...


This same wiki article said the 109E fighter bombers came in over 20000'. Carrying a 550lb bomb they couldn't have flown much over 20000'. A long way from 30000'. 

The LW switched to night attacks from September 15, were these flown at 30000'? I just don't see much at all about 30000' in the BoB.


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## P-39 Expert (Jun 30, 2021)

pbehn said:


> Where in my post did I mention the BoB, the BoB as an event was over, the RAF still had to defend its airspace which in 1942 meant interceptions at 42,000ft and low level tip and run raiders all along the south coast, again the P-39 would be useless at this, which is why the British sent the malfunctioning rubbish away. I no longer care what you are convinced of because nothing convinces you of anything. What is serious and consistent? Isnt 2,600 in a month serious and consistent? The link if you read it says "and the British defences had difficulty detecting and intercepting the *high-flying* and fast fighter-bomber formations. "
> 
> High flying means high altitude, that is not low or medium but high. 10,000ft isnt high, 20,000ft isnt high 25-30000ft is high.


Exactly how many interceptions at 42000' did the RAF achieve? One?

High flying and fast fighter bomber formations? Those 109Es were carrying 550lb bombs which severely limited any high altitude operations. Wiki said they cam in over 20000', not 30000'. And how did they bomb with any accuracy? In formation? As dive bombers?


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## pbehn (Jun 30, 2021)

P-39 Expert said:


> Exactly how many interceptions at 42000' did the RAF achieve? One?
> 
> High flying and fast fighter bomber formations? Those 109Es were carrying 550lb bombs which severely limited any high altitude operations. Wiki said they cam in over 20000', not 30000'. And how did they bomb with any accuracy? In formation? As dive bombers?


As per my previous post, Chain Home couldnt accurately tell altitude at those altitudes so they had to send up planes to look, the subject of discussion is whether an RAF interceptor in the BoB and later had to get up to 30,000ft and whether they did that, the answer to both is YES. If a Bf109E could get to 32,000 how do you know how much a 550lb bomb would affect it? You claim the P-39 could get close to that with half a ton of extra junk.

They only had to achieve one to stop the game, how many sorties were done before that one interception? Twelve, one of them dropped a 550LB bomb in a bus station killing 48 people and wounding 56, how may more would they have done? As many as they wanted until stopped.


P-39 Expert said:


> This same wiki article said the 109E fighter bombers came in over 20000'. Carrying a 550lb bomb they couldn't have flown much over 20000'. A long way from 30000'.
> 
> The LW switched to night attacks from September 15, were these flown at 30000'? I just don't see much at all about 30000' in the BoB.


You said it never happened, I pointed out the high altitude attacks in October which were fighter bombers and fighters, now you exclude fighters why? The subject is the altitudes planes met not the exact altitude a plane carrying a bomb flew. You also bring in frequency, why? It happened and the RAF needed planes to get there and that wasnt the P-39 so they were sent away. 

You are now side tracking into specific altitudes on specific dates and giving your thoughts on their significance, it didnt matter if they had a bomb on them, if they were there they had to be intercepted and the P-39 was useless at it, completely utterly useless especially since they only got 4 in squadron service in 1941.

Any more groundhoggery?

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## P-39 Expert (Jun 30, 2021)

Shortround6 said:


> You might be interested to know that the heating of the cabin of the P-39C and D was very good because they used a Stewart-Warner gasoline type heater.
> 
> This is stated in the pilots manuals.
> 
> So, NO, the British did NOT load the plane down with useless stuff like a fuel powered heater, it was already there.


The British specified the gas heater in the P-400.

The P-39D ducted warm air from the rear of the coolant radiator up under the pilot's seat for cabin heat. Standard arrangement from the D model onward. No gas heater for the P-39D onward.


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## pbehn (Jun 30, 2021)

P-39 Expert said:


> The British specified the gas heater in the P-400.
> 
> The P-39D ducted warm air from the rear of the coolant radiator up under the pilot's seat for cabin heat. Standard arrangement from the D model onward. No gas heater for the P-39D onward.


Did the British specify taking out a ducted air system and putting in an American suppliers gasoline heater for the cabin?


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## Milosh (Jun 30, 2021)

P-39 Expert said:


> Exactly how many interceptions at 42000' did the RAF achieve? One?


Enough that Ju86s were withdrawn from service by July '44

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## buffnut453 (Jun 30, 2021)

P-39 Expert said:


> The British specified the gas heater in the P-400.
> 
> The P-39D ducted warm air from the rear of the coolant radiator up under the pilot's seat for cabin heat. Standard arrangement from the D model onward. No gas heater for the P-39D onward.



And what about the P-39C? Did that use a gas heater? 
S
 Shortround6
stated it was both the P-39C and D that had the gas heater. You've made the claim that the D didn't have one...so what about the C? The P-39C was the Bell Model 13 while the P-400 was the model 14, hence the P-39C design came first. If the C had the gas heater, then it was "standard" for the type at that stage, which means the British didn't specify the gas heater as an exception.

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## Shortround6 (Jun 30, 2021)

From page 4 of the Flight Operating Instructions for the P-39D-1 and P-39D-2 aircraft, dated Nov 10th 1942. 

I. Heating and Ventilation. 
The Cockpit is heated by a Stewart-Warner gasoline type heater. The heater control toggle switch(fig 6-17) is located on the main control switch panel. A heater warning light
(fig 6-33), located on the right auxiliary instrument panel, will light if the heater is not getting sufficient fuel, if the exhaust line to the supercharger is leaking or if the heater system gets too hot.

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## SaparotRob (Jun 30, 2021)

Don't believe everything you read.

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## buffnut453 (Jun 30, 2021)

P-39 Expert said:


> Every one of you guys are masters at taking a general statement and finding a very small number of exceptions and then stating that I'm wrong. It was a big war with lots of exceptions to every rule.



And, in return, you either ignore responses and refuse to answer questions, or you ignore evidence that contradicts your general statements....or you continue to restate opinions that have been debunked. 

Here's two penn'orth of free advice for you:

1. Stop making general comments that aren't backed up by facts. For example, you said that no fighters got up to 30,000ft during the BoB. That's patently untrue and no amount of dissembling (e.g. making (again) unsupported claims about the number of sorties at that altitude) will change the fact that your statement was just plain wrong. 

2. Stop viewing every engagement on this forum as an argument that you have to win. This thread would be much more productive if you would demonstrate a willingness to learn new facts rather than clinging to old opinions. You criticize others for not accepting your arguments and yet any view contrary to yours is met with the responses listed above. Rather than simply dismissing the contributions of others, maybe occasionally you might try a different tack...for example, perhaps thanking them for making you aware of something that you didn't know.

Your knowledge about the P-39 is impressive and I've learned a lot from your posts. In particular, some variants did have better performance than I'd previously accepted. But (and it's a BIG BUT) those better-performing variants arrived after other designs were already in service with at least as good if not better performance.

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## buffnut453 (Jun 30, 2021)

Shortround6 said:


> From page 4 of the Flight Operating Instructions for the P-39D-1 and P-39D-2 aircraft, dated Nov 10th 1942.
> 
> I. Heating and Ventilation.
> The Cockpit is heated by a Stewart-Warner gasoline type heater. The heater control toggle switch(fig 6-17) is located on the main control switch panel. A heater warning light
> (fig 6-33), located on the right auxiliary instrument panel, will light if the heater is not getting sufficient fuel, if the exhaust line to the supercharger is leaking or if the heater system gets too hot.



Since the early P-39Ds started out as P-39Cs, I suspect the gas heater was a carry-over from the C-variant.


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## pbehn (Jun 30, 2021)

My guess is the client specified that the cabin should be heated and the gasoline heater was what Bell proposed until they had sorted out a ducted system. The resulting agreed specification doesnt mean that the British specified anything, clients specify requirements and accept or reject proposals. If the British had this requirement (like instruments or guns) it is a global requirement and it would have been the same for the P-40 and Mustang MkI + all British made fighters. Did any other military plane use these heaters? Or is this added to the many other myths about what the eccentric British got up to, trying to screw Bell up?


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## Shortround6 (Jun 30, 2021)

from the Operation and Flight Instructions for the YP-39 and P-39C pursuit airplanes, dated Feb 15th 1941. Page 6.

"d. heating and ventilating equipment. - A Stewart-Warner Cabin heater is provided. A ventilator is installed in the left side of the cabin enclosure. A shutter, installed in the ventilator, is operated by a control located at the pilot's left. "

This is pretty basic and does not say the Stewart-Warner is a combustion (fuel) heater. But why designate it by brand name unless it was well known? If it was a car type heater core and duct why use the Brand name of a combustion heater company? 
Stewart-Warner built combustion heaters for A-20s and other aircraft and also built ground heaters for warming up engines prior to starting.


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## nuuumannn (Jun 30, 2021)

P-39 Expert said:


> BoB got nowhere near 30000ft.



Umm, yes it did. Bf 109s carried out fighter sweeps from higher altitudes while escorting bomber formations. RAF fighters had difficulty intercepting them, but the German tactic was to dive down upon the attacking RAF aircraft then climb back to height. Dog fights, which is what usually broke out once the Bf 109s dived among the RAF fighters tended to descend with altitude, but yes, altitudes of over 30,000 ft were flown by the Bf 109s. And wot Pbehn said.


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## nuuumannn (Jun 30, 2021)

P-39 Expert said:


> I just have a hard time believing those accounts. With the altitude statistics of the day.



This is because you get all your information from charts and not from things like combat reports, historical accounts etc. Charts don't tell the whole story and are not always representative of real-world conditions. They are produced from test operations under controlled conditions for the purpose of recording standard performance data, but don't always represent every single aircraft, nor do they represent specific combat arenas, where conditions were frequently different on a daily basis.


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## Greg Boeser (Jun 30, 2021)

P-39 Expert said:


> Okay, how many P-40s with .30calMGs served in the AAF after Pearl Harbor?


In an active war zone? Or just in the AAF.
Those based in the PI were mostly wiped out on December 8.
The 23rd FG, the successor to the AVG, took over the aircraft of the AVG, predominantly H-81s, on July 4, 1942, and continued to fly them in combat during the later half of 1942
Other units in the US and the Canal Zone continued to operate them for defensive or training purposes, but did not see combat.
But you bring up an excellent point. By the end of 1941, the USAAF and USN were equipping with fighters that were armed with 4-6 wing mounted .50 caliber MGs. Fighters with nose mounted, synchronized MGs were considered obsolete. The P-39, still armed with synchronized MGs and wing mounted .30 caliber guns was therefore obsolete before it entered combat. Why didn't Bell put .50 cals in the wings? There wasn't room. In the Q they slung a single .50 under each wing. Still wasn't good enough

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## buffnut453 (Jun 30, 2021)

P-39 Expert said:


> Okay, how many P-40s with .30calMGs served in the AAF after Pearl Harbor?



Can't give you a number but here are some P-40Cs still in front line service defending the Panama Canal in 1943:

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## Shortround6 (Jun 30, 2021)

P-39 Expert said:


> Where did you see the 600yds range for the .30cal? Edit: Oh, sorry, I see it now. AHT lists 200yds as the max practical range. Why would we want the max theoretical range?



Without knowing the criteria or method of figuring out either the practical range or the theoretical range we are simply speculating. 

As I have said, AHT is a very good source but that table has a number of errors and inconstancies. 

One _might_ define practical range as the range that has some combination of probability of hitting plus the potential to do a certain amount of damage. It may have something to do with the amount of rounds fired to get a certain amount of damage. 
Max theoretical range may be the range at which a golden BB hit will still do something? but a hit from a 37mm doesn't need to be golden BB, it just needs to hit. 

Without having any idea of the criteria used it is impossible to critique. 


I would also note that both the practical range and theoretical range will change with altitude. Higher altitudes with thinner air mean less drag, shorter times of flight and more impact energy. 

Germans figured the MG 131 had an effective range of 400 meters against bombers but a max range of 700 meters at 3000 meters altitude and a max range of 1000 meters at 6000 meters altitude. The 15mm MG 151 is listed as having a 600 meter effective range, max range of 800 meters at 3000 m altitude and 1,100 meters amx range at 6000 meters altitude. 

However this is complicated by the fact that the 13mm MG 131 was a pretty crappy long range gun/cartridge. At sea level it lost 55% of it's velocity by the time it had gone 600 meters and the time of flight was 1.22 seconds. The much higher velocity MG 151 lost 39% of it's velocity and and a time of flight of just 0.816 seconds to the same distance. 
For a real head scratcher the AP round out of the MG 17 was rated as having an effective range of just 200 meters. But it lost57% of it's initial velocity in 600 meters but since it started faster than the MG 131 it's time of flight to 600 meters was 1.159 seconds, not really much better than the MG 131 but since it is going to arrive at pretty much the same time and have about the same drop why does it have such a short effective range? Granted it won't do as much damage but it's chances of hitting would seem to be as good.

BTW the .50 cal loses less velocity and has shorter times of flight to given distances than the 20mm Hispano which really calls into question the numbers in the AHT chart.

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## buffnut453 (Jun 30, 2021)

buffnut453 said:


> Can't give you a number but here are some P-40Cs still in front line service defending the Panama Canal in 1943:
> 
> View attachment 630621



FWIW the fighter ORBAT in Hawaii on 7 December 1941 comprised:

14 x P-26
39 x P-36A
87 x P-40B
12 x P-40C

So...none of the fighters present had 50cals in the wings. 

In addition to the above there were 71 x P-40Bs and 26 x P-35s in the Philippines on 7 December 1941. Some 20 x P-40Es had arrived shortly before the Japanese attacked.

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## nuuumannn (Jun 30, 2021)

P-39 Expert said:


> And you're telling me Spitfire I and 109E in 1940 routinely got over 30000ft?



According to trials done by the Aircraft and Armament Experimental Establishment (A&AEE) in *November 1939* with Spitfire Mk.I N3171 fitted with a Merlin III engine, its maximum altitude recorded was *34,700 ft.* To put that into perspective, the first Airacobra I tested by the A&AEE in _August 1941_ recorded a maximum altitude of 29,000 ft. 

The Airacobra's performance overall was poorer than that of the Spitfire VC AA873 with a Merlin 45, on which performance trials was carried out in October 1941, the Airacobra recording a maximum speed of 365 mph at 15,600 ft and a rate of climb of 1,845 ft/min to 12,500 ft, taking 12.4 minutes. The Spitfire VC recorded a maximum speed of 374 mph at an altitude of 19,000 ft and a rate of climb of 2,900 ft/min to 13,400 ft, taking 7.4 minutes.

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## nuuumannn (Jun 30, 2021)

buffnut453 said:


> Can't give you a number but here are some P-40Cs still in front line service defending the Panama Canal in 1943:



Cool photo, and a solitary Cessna Bobcat too...

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## special ed (Jun 30, 2021)

This has reminded me of three gentlemen who came to a Civil Air Patrol senior meeting sometime in the 1970s to show a 16mm B&W movie of P-40 long noses of the AVG in the 23rd used for ground attack. They carried rocket tubes bundled in three under each wing and were live fire training. I had never seen bundles of three tubes on the old p-40s the way I had on much newer fighters.


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## P-39 Expert (Jul 1, 2021)

Shortround6 said:


> Without knowing the criteria or method of figuring out either the practical range or the theoretical range we are simply speculating.
> 
> As I have said, AHT is a very good source but that table has a number of errors and inconstancies.
> 
> ...


Good information. You made a comment in a previous post about the projectile weight of the 30cal round. Were the actual rounds used lighter?

AHT also listed the 37mm as firing 90rounds per minute, when it actually fired 150. Big increase in weight of fire per second.

Quoted from the AHT Armament section: "The .30cal MG fell by the wayside as the war progressed...limitations in range and hitting power of this weapon were very evident...With half again the range and two and one half times the hitting power (based on delivered projectile weight per second) the advantages of the .50cal over the .30cal could not be ignored." That's all I know about the subject. Thanks for the information.


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## pbehn (Jul 1, 2021)

nuuumannn said:


> Umm, yes it did. Bf 109s carried out fighter sweeps from higher altitudes while escorting bomber formations. RAF fighters had difficulty intercepting them, but the German tactic was to dive down upon the attacking RAF aircraft then climb back to height. Dog fights, which is what usually broke out once the Bf 109s dived among the RAF fighters tended to descend with altitude, but yes, altitudes of over 30,000 ft were flown by the Bf 109s. And wot Pbehn said.


There was also a phenomenon that developed earlier in the battle. The RAF vectored an interception to a raid, and it was bounced. So squadrons started adding a few thousand to the vector height, and sometimes missed the interception completely, the LW sent squadrons higher looking to come out of the sun, so Park sent flights on patrol even higher looking to do the same.

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## P-39 Expert (Jul 1, 2021)

Greg Boeser said:


> In an active war zone? Or just in the AAF.
> Those based in the PI were mostly wiped out on December 8.
> The 23rd FG, the successor to the AVG, took over the aircraft of the AVG, predominantly H-81s, on July 4, 1942, and continued to fly them in combat during the later half of 1942
> Other units in the US and the Canal Zone continued to operate them for defensive or training purposes, but did not see combat.
> But you bring up an excellent point. By the end of 1941, the USAAF and USN were equipping with fighters that were armed with 4-6 wing mounted .50 caliber MGs. Fighters with nose mounted, synchronized MGs were considered obsolete. The P-39, still armed with synchronized MGs and wing mounted .30 caliber guns was therefore obsolete before it entered combat. Why didn't Bell put .50 cals in the wings? There wasn't room. In the Q they slung a single .50 under each wing. Still wasn't good enough


Agree with you about the .30s on the P-40. Of the hundred thousand fighters built in the US for WW2 only a handful of P-40B/C (and the P-39) actually used the .30s in combat. And .30s were used on the Mustang I but that plane was used by the British. The AAF/USN fought the war with .50s and 20mm cannon and a few 37mm cannon.

Disagree with you that the synchronized .50s made the P-39 obsolete. Over a hundred thousand German and Russian fighters used synchronized guns. And the nose cannon and synchronized .50s were sufficient armament in WW2. Just my opinion.


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## P-39 Expert (Jul 1, 2021)

Shortround6 said:


> from the Operation and Flight Instructions for the YP-39 and P-39C pursuit airplanes, dated Feb 15th 1941. Page 6.
> 
> "d. heating and ventilating equipment. - A Stewart-Warner Cabin heater is provided. A ventilator is installed in the left side of the cabin enclosure. A shutter, installed in the ventilator, is operated by a control located at the pilot's left. "
> 
> ...



"The Design Analysis of the Bell Airacobra" (Aviation Magazine) details the structural systems and weights for the P-39D.  It shows the normal cabin ventilation system of warm air ducted into the cabin (and nose gun bay) from the coolant radiator exhaust just like the subsequent P-39s. There were only 13 YPs and 20 P-39Cs manufactured before series production began with the D. I didn't realize the D-1 and D-2 used the Stewart-Warner cabin heater. They were the Bell model 14 like the P-400 and were often listed as "export" models. Production was relatively small with only 336 D-1 and 158 D-2 models built. The D/F model was the Bell model 15 with the normal ducted heat system as were the subsequent model 26 for the K/L/M/N/Q. Of the 9500+ P-39s built only 527 (13+20+336+158) had the gas heater and those models were completed by summer of '42.

Thanks for the information on the YP, C, D-1 and D-2. Your information is always appreciated.


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## pbehn (Jul 1, 2021)

So the British didnt specify the cabin heater, I am glad we cleared that up at least.


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## Shortround6 (Jul 1, 2021)

P-39 Expert said:


> Disagree with you that the synchronized .50s made the P-39 obsolete. Over a hundred thousand German and Russian fighters used synchronized guns. And the nose cannon and synchronized .50s were sufficient armament in WW2.


We have been over this before. The American Browning did not take to synchronization well. It lost a lot of rate of fire. 
The US .50 was powerful but it was heavy, The German guns had a good rate of fire, even when synchronized, they were light. 
The Russians used a 7.62 gun to start and rapidly went to the 12.7mm. Their 12.7mm was both light and had a high rate of fire. 

Gun................................weight...........................rate of fire 
MG 17............................12.6kg..........................1000-1100rpm S
MG 131..........................17 kg.............................about 800rpm S
ShKAS (7.62).................7.1kg...........................1800 rpm unsyc
Berezin (12.7)................25kg.............................800rpm S
US .30 cal........................10kg ...........................1200rpm unsyc
US .50 cal........................29kg.............................as low as 450rpm when synchronized, later ones may have been somewhat faster. perhaps 600rpm?

Russians are a poor example as they deliberately cut armament to avoid sacrificing performance due to the low power of the M-105 engine. 
Even the LA-5 and LA-7 had weight issues. When the 25kg B-20 20mm gun was introduced the LA fighters went to 3 guns instead of two 42kg ShVAK cannon. 
The MG 131 was deliberately designed to fit (mostly) into the space of the MG 17 and was the lowest power (individual cartridge) heavy machine gun used in WW II. 

The Russians also show how different reasons can affect armament selection. They changed from the ShKAS to the Berezin not only to get the larger more powerful 12.7mm round but because the high rate of fire and light ShKAS required a lot of skilled work to manufacture/assemble and the larger Berezin was actually cheaper/easier to make. 

Synchronized .50 cal Brownings may not have been "obsolete" but they didn't offer as much hitting power for their weight (bang for buck?) as some other set ups.


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## Shortround6 (Jul 1, 2021)

From the ""The Design Analysis of the Bell Airacobra" (Aviation Magazine)"
Air is exhausted from the cabin through ducts over the rudder pedal well. These ducts lead to the cannon and .50-cal machine guns. The air supply to the cabin is constant and only temperature may be regulated. Because of this, there is greater air pressure in the cabin than in the gun compartment, thus preventing fumes from the gun compartment entering the cabin.

Hmmmm, a fix for the gun fumes noted in the cockpit by the British after firing the guns? 
perhaps having nothing to do with the weight of the gasoline heater?
A number of American light planes (like Cessna's) used gasoline fueled cabin heaters. Granted they used air cooled engines.

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## Peter Gunn (Jul 1, 2021)

P-39 Expert said:


> Stop putting words in my mouth. I have never said that the P-39 was able to do the Mustang's job. I have said that P-39s could have escorted B-17/24s in Europe, certainly not as far or as well.


Well, you ARE the one that said a P-39 could escort B-17's and B-24's in the ETO, if that isn't the Mustangs job I don't know what is.

Also I've been pondering this "British adding weight to kill the P-39" issue. Didn't the "British" have dealings (aviation wise) with:

A). Lockheed
B). Boeing
C). Douglas
D). North American
E). Grumman
F). Chance-Vought

At what point did they try to "sabotage" the Mustang, or the Hudson or the Wildcat etc? I suppose you could make an argument for the P-38 but I've never seen any real evidence of them singling out Bell for this underhanded treachery.

Unless perhaps Dutch Kindleberger had pictures of one of the BPC screwing a goat or something.

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## pbehn (Jul 1, 2021)

Peter Gunn said:


> Also I've been pondering this "British adding weight to kill the P-39" issue. Didn't the "British" have dealings (aviation wise) with:
> 
> A). Lockheed
> B). Boeing
> ...


There were similar sentiments about the British use of the B-17, by the time the USA started using the B-17 everything the British said had been acted upon or was found out to be true.

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## 33k in the air (Jul 1, 2021)

P-39 Expert said:


> AHT also listed the 37mm as firing 90rounds per minute, when it actually fired 150. Big increase in weight of fire per second.



With only 30 rounds carried, I don't think the firing rate is going to make much of a difference.

It might be all right for going after bombers, but scoring hits on faster, smaller, and sharply maneuvering fighters is another matter entirely.


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## DerAdlerIstGelandet (Jul 1, 2021)

buffnut453 said:


> And, in return, you either ignore responses and refuse to answer questions, or you ignore evidence that contradicts your general statements....or you continue to restate opinions that have been debunked.
> 
> Here's two penn'orth of free advice for you:
> 
> ...


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## P-39 Expert (Jul 1, 2021)

Shortround6 said:


> From the ""The Design Analysis of the Bell Airacobra" (Aviation Magazine)"
> Air is exhausted from the cabin through ducts over the rudder pedal well. These ducts lead to the cannon and .50-cal machine guns. The air supply to the cabin is constant and only temperature may be regulated. Because of this, there is greater air pressure in the cabin than in the gun compartment, thus preventing fumes from the gun compartment entering the cabin.
> 
> Hmmmm, a fix for the gun fumes noted in the cockpit by the British after firing the guns?
> ...


Only the P-400, D-1 and D-2 had the gasoline heater. The rest had the heating system you described.


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## P-39 Expert (Jul 1, 2021)

33k in the air said:


> With only 30 rounds carried, I don't think the firing rate is going to make much of a difference.
> 
> It might be all right for going after bombers, but scoring hits on faster, smaller, and sharply maneuvering fighters is another matter entirely.


12 seconds of firing time. P-38 had 15 seconds for their 20mm, Spitfire had 12 seconds for theirs.


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## P-39 Expert (Jul 1, 2021)

Peter Gunn said:


> Well, you ARE the one that said a P-39 could escort B-17's and B-24's in the ETO, if that isn't the Mustangs job I don't know what is.
> 
> Also I've been pondering this "British adding weight to kill the P-39" issue. Didn't the "British" have dealings (aviation wise) with:
> 
> ...


They sure did refuse to pay for the P-38 Lightning equipped as they specified it.


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## 33k in the air (Jul 1, 2021)

P-39 Expert said:


> 12 seconds of firing time. P-38 had 15 seconds for their 20mm, Spitfire had 12 seconds for theirs.



The P-38 carried 150 rounds for its 20mm cannon.

More rounds carried means more opportunity to actually score a hit.


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## pbehn (Jul 1, 2021)

P-39 Expert said:


> They sure did refuse to pay for the P-38 Lightning equipped as they specified it.


I think we went through this before, was it one aircraft or four, how many of the planes the USA wouldnt send (because they themselves were now at war) did they refuse to take? This anti British BS of yours is getting personally insulting. Now, again, where did the British specify that Bell take off their wonderful ducted system and add a gasoline heater as you claimed.


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## P-39 Expert (Jul 1, 2021)

Shortround6 said:


> We have been over this before. The American Browning did not take to synchronization well. It lost a lot of rate of fire.
> The US .50 was powerful but it was heavy, The German guns had a good rate of fire, even when synchronized, they were light.
> The Russians used a 7.62 gun to start and rapidly went to the 12.7mm. Their 12.7mm was both light and had a high rate of fire.
> 
> ...


Not arguing with you at all. But the twin .50s did have some rate of fire and none of us can seem to find out exactly what it was. Whatever it was it worked out to be some percentage of one .50calMG. By my calculations I have always maintained that the rate of fire was 75% of normal. That means that both MGs put out the equivalent of 1.5 .50s. 

The Navy calculated that one 20mm cannon was worth three .50calMGs. 37mm cannon had just about the same weight of fire/sec (AHT). Coupled with the 1.5 equivalent .50calMGs then the P-39 had the equivalent of 4.5 .50calMGs. I think that was adequate as compared to the P-51A/B/C, FM2 Wildcat, and F8F Bearcat that were armed with 4 .50calMGs. Plus the P-39 had the benefit of centerline fire and the exploding shell.


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## P-39 Expert (Jul 1, 2021)

pbehn said:


> So the British didnt specify the cabin heater, I am glad we cleared that up at least.


Yes they did, see subsequent posts.


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## pbehn (Jul 1, 2021)

P-39 Expert said:


> Yes they did, see subsequent posts.


I havnt seen that the British specified it, all I have seen is that is all Bell had at the time, until they got their ducted system sorted out, the gasoline heater was modified as far as I can see following British comments that the cabin filled with smoke.


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## P-39 Expert (Jul 1, 2021)

nuuumannn said:


> This is because you get all your information from charts and not from things like combat reports, historical accounts etc. Charts don't tell the whole story and are not always representative of real-world conditions. They are produced from test operations under controlled conditions for the purpose of recording standard performance data, but don't always represent every single aircraft, nor do they represent specific combat arenas, where conditions were frequently different on a daily basis.


Yes I do get the vast majority (not all) my information from official AAF Wright Field tests (wwiiaircraftperformance.org). I tend to view combat reports and historical accounts as similar to victory claims, which often were exaggerated by 2 or 3 times. All those men telling the tales had agendas and personal biases and other differences from the truth, whether intentional or not. Chuck Yeager, yes I believe pretty much everything he says. Edwards Park, ditto. But Joe Pilot who thinks he got up to 30000' in a Spitfire 1 with a service ceiling of 35000' and a combat ceiling of 26000'? Not so much. Not calling Joe a liar, just saying that if what he said was true then it was one of the rarest of occurrences. Just my opinion.

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## pbehn (Jul 1, 2021)

P-39 Expert said:


> Yes I do get the vast majority (not all) my information from official AAF Wright Field tests (wwiiaircraftperformance.org). I tend to view combat reports and historical accounts as similar to victory claims, which often were exaggerated by 2 or 3 times. All those men telling the tales had agendas and personal biases and other differences from the truth, whether intentional or not. Chuck Yeager, yes I believe pretty much everything he says. Edwards Park, ditto. But Joe Pilot who thinks he got up to 30000' in a Spitfire 1 with a service ceiling of 35000' and a combat ceiling of 26000'? Not so much. Not calling Joe a liar, just saying that if what he said was true then it was one of the rarest of occurrences. Just my opinion.


You are beyond belief, a test pilot isnt Joe Pilot and any pilot deserves the same respect as Chuck Yaeger, who just happened to break the sound barrier in a Bell aircraft. Just as when the RAF leaned into France in 1941 escorts and attackers tried to outflank each other by climbing higher, that is a fact, your opinion doesnt matter because that is a fact, and there is no one telling tales with an agenda more than you.


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## SaparotRob (Jul 1, 2021)

No, there is another.


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## Milosh (Jul 1, 2021)

So that instrument on the panel called an altimeter was just a useless piece of equipment.

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## pbehn (Jul 1, 2021)

Milosh said:


> So that instrument on the panel called an altimeter was just a useless piece of equipment.


Only in British hands in 1939 to 45.

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## DerAdlerIstGelandet (Jul 1, 2021)

Milosh said:


> So that instrument on the panel called an altimeter was just a useless piece of equipment.



I took my plane to 11,000 ft before. I can’t be trusted to say that though, because I’m just a joe pilot.

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## Thumpalumpacus (Jul 1, 2021)

pbehn said:


> Any more groundhoggery?



I love this word you've invented. It's descriptive and useful


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## pbehn (Jul 1, 2021)

DerAdlerIstGelandet said:


> I took my plane to 11,000 ft before. I can’t be trusted to say that though, because I’m just a joe pilot.


You can, because you cant interfere with the narrative that the British had no reason to reject the P-39 but they did out of spite greed or incompetence, which is what this is all about. All sorts of interesting info has been accepted but nothing that interferes with that basic story.


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## Thumpalumpacus (Jul 1, 2021)

Peter Gunn said:


> Unless perhaps Dutch Kindleberger had pictures of one of the BPC screwing a goat or something.



Wait, I thought we all had that pic. You don't?

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## buffnut453 (Jul 1, 2021)

For a few posts we had a reasonable discussion but now we’re back to normal. The gas heater was standard equipment on the P-39C that immediately preceded the P-400, AND it was standard equipment on the P-39D1 and D2 which immediately followed the P-400. And yet it was those perfidious Brits who deliberately specified the gas heater to add unnecessary weight to the aircraft.

Then we have the incredibly dismissive attitude to an official combat report that was filed by the man leading an entire Spitfire squadron on operations at 30K feet. Apparently, that experienced combat veteran was over claiming his altitude….but, as usual, no rationale for such a ridiculous claim is made. He was just incompetent and couldn’t read an altimeter (but he could lead a fighter squadron into combat…and score kills).

This really is beyond the pale. If any Brit made such a claim about an American pilot, they’d be kicked off the forum. Apparently all Brits are liars, cheats and all round dishonest operators.


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## DerAdlerIstGelandet (Jul 1, 2021)

buffnut453 said:


> This really is beyond the pale. *If any Brit made such a claim about an American pilot, they’d be kicked off the forum.* Apparently all Brits are liars, cheats and all round dishonest operators.



No, they would just lose credibility as in the case now.

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## P-39 Expert (Jul 1, 2021)

buffnut453 said:


> And, in return, you either ignore responses and refuse to answer questions, or you ignore evidence that contradicts your general statements....or you continue to restate opinions that have been debunked.
> 
> Here's two penn'orth of free advice for you:
> 
> ...


Thanks for the advice. Now here's some advice for you.

Almost every comment I make is backed up by facts, either from wwiiaircraftperformance.org or other Govt/AAF source or AHT or Vees for Victory or some other original source reference like that. While I am sure that a very few Spitfires, Hurricanes and 109Es actually made it to 30000', I am also sure that was a very rare occurrence and certainly not something that happened daily, much less as a significant part of the day to day BoB. German bombers (He111, Ju88, Do217) operated between 16000' and 20000' and not much higher than that at all. That's what reference material on the BoB says and that is borne out by published performance figures on those planes. The LW fighters were instructed to stay as close as possible to the bombers and even the AAF escorts in 1944 were not to get more than 3000' above the bomber stream. 109E escorts had a combat ceiling (1000fpm) of about 27000' but were instructed to stay much closer to their bombers than 7000' to 13000' above. Whether they could even get to 30000' is questionable. And there is no way that a 109E with a 550lb bomb can get to 30000'. Maybe they could fly higher than the bombers, but they aren't getting to 30000' with the extra weight and drag of that bomb. No reference says they got to 30000', just that they flew higher than the bombers. Now maybe a special LW reconnaissance plane could get near 30000' and maybe a Spitfire I tried it's best to intercept, but that was not even a daily occurrence and was still very rare. Very few of my statements are just plain wrong and when they are I admit it.

I don't view every engagement as an argument that has to be won. I do quote a lot of published facts and try to stay away from personal accounts (heresay) and when people disagree with my statements I do try to reiterate the facts that I have posted and try to show them why I believe those facts are correct. I post very very few opinions and when I do I try to state that in my posts, "this is just my opinion". I am always courteous even when other posters are not and I have hardly ever criticized anyone on this board even when they are calling me every name in the book. I know some (most) (all) of my posts are unpopular but they are based on facts that disagree with long held and quoted views. There is newer factual information (wwiiaircraft) that has been made available recently (2012) that refutes a lot of what we have been told for the last 75 years. It's wrong and it needs to be updated.

Finally "but those better-performing (P-39) variants arrived after other designs were already in service" is the main myth that I am trying to expose. The P-39 was available at the beginning of the U.S. involvement in WWII. And the much improved models with uprated engines (N) were available from the fall of 1942 just as the P-38F/G was entering combat and well before the P-47, P-51B/C/D, F4U and Hellcat entered combat. Performance was on par with the 109G and FW190A and vastly superior to the A6M2, A6M5 and Ki-43. These are facts as borne out by Wright Field tests and results from the main users, the Soviets. It was one of the best planes around in 1943. That's all I'm saying. But every time I state some facts from test results or other references lots of people on here act like I have insulted their mother or called Uncle Sam a communist, just because it doesn't agree with what they have read or heard. Comparing airplanes has to be done by date, or you are just comparing a SPAD with an F-22. Rant over.


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## Milosh (Jul 1, 2021)

After the arrival of the initial aircraft in the UK in October 1941, the first Mustang Mk Is entered service in January 1942, the first unit being 26 Squadron RAF.

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## pbehn (Jul 1, 2021)

P-39 Expert said:


> Thanks for the advice. Now here's some advice for you.
> 
> Almost every comment I make is backed up by facts, either from wwiiaircraftperformance.org or other Govt/AAF source or AHT or Vees for Victory or some other original source reference like that. While I am sure that a very few Spitfires, Hurricanes and 109Es actually made it to 30000', I am also sure that was a very rare occurrence and certainly not something that happened daily, much less as a significant part of the day to day BoB. German bombers (He111, Ju88, Do217) operated between 16000' and 20000' and not much higher than that at all. That's what reference material on the BoB says and that is borne out by published performance figures on those planes. The LW fighters were instructed to stay as close as possible to the bombers and even the AAF escorts in 1944 were not to get more than 3000' above the bomber stream. 109E escorts had a combat ceiling (1000fpm) of about 27000' but were instructed to stay much closer to their bombers than 7000' to 13000' above. Whether they could even get to 30000' is questionable. And there is no way that a 109E with a 550lb bomb can get to 30000'. Maybe they could fly higher than the bombers, but they aren't getting to 30000' with the extra weight and drag of that bomb. No reference says they got to 30000', just that they flew higher than the bombers. Now maybe a special LW reconnaissance plane could get near 30000' and maybe a Spitfire I tried it's best to intercept, but that was not even a daily occurrence and was still very rare. Very few of my statements are just plain wrong and when they are I admit it.
> 
> ...


You dismiss facts with your opinion, you cringe at facts and have a hard time believing facts that dont fit your opinion. The latest is this nonsense about heaters, why would the British specify an American heater when they didnt on any other airplane anywhere ever? It is nonsense that you cling to because that is your narrative. The British did not specify that heater, Bell had nothing else, until they sorted their ducted system, until that time the USA had P-39s with the same heater, didnt they? So they must have specified them, didn't they? You have more than an agenda it is like a mission to convince the world that the P-39 could have done everything including bomber escort if it wasnt for the pesky British. Well if the P-39 of any model could have escorted US bombers why couldnt the Mustang MkI or the P-51A? Why were the Americans so stupid as to put a Merlin in a P-51 when they had the answer there already?

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## GrauGeist (Jul 1, 2021)

By the way, was that 30K AGL or ASL?

Asking for a friend.

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## pbehn (Jul 1, 2021)

GrauGeist said:


> By the way, was that 30K AGL or ASL?
> 
> Asking for a friend.


Is that the British sea level or other, the British are known to talk about tides which means the fools dont believe that the sea is level, they also use this sea-unlevelness to refuse to pay up for contracts, FACT!

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## buffnut453 (Jul 1, 2021)

P-39 Expert said:


> Thanks for the advice. Now here's some advice for you.
> 
> Almost every comment I make is backed up by facts, either from wwiiaircraftperformance.org or other Govt/AAF source or AHT or Vees for Victory or some other original source reference like that. While I am sure that a very few Spitfires, Hurricanes and 109Es actually made it to 30000', I am also sure that was a very rare occurrence and certainly not something that happened daily, much less as a significant part of the day to day BoB. German bombers (He111, Ju88, Do217) operated between 16000' and 20000' and not much higher than that at all. That's what reference material on the BoB says and that is borne out by published performance figures on those planes. The LW fighters were instructed to stay as close as possible to the bombers and even the AAF escorts in 1944 were not to get more than 3000' above the bomber stream. 109E escorts had a combat ceiling (1000fpm) of about 27000' but were instructed to stay much closer to their bombers than 7000' to 13000' above. Whether they could even get to 30000' is questionable. And there is no way that a 109E with a 550lb bomb can get to 30000'. Maybe they could fly higher than the bombers, but they aren't getting to 30000' with the extra weight and drag of that bomb. No reference says they got to 30000', just that they flew higher than the bombers. Now maybe a special LW reconnaissance plane could get near 30000' and maybe a Spitfire I tried it's best to intercept, but that was not even a daily occurrence and was still very rare. Very few of my statements are just plain wrong and when they are I admit it.
> 
> ...





P-39 Expert said:


> Thanks for the advice. Now here's some advice for you.
> 
> Almost every comment I make is backed up by facts, either from wwiiaircraftperformance.org or other Govt/AAF source or AHT or Vees for Victory or some other original source reference like that. While I am sure that a very few Spitfires, Hurricanes and 109Es actually made it to 30000', I am also sure that was a very rare occurrence and certainly not something that happened daily, much less as a significant part of the day to day BoB. German bombers (He111, Ju88, Do217) operated between 16000' and 20000' and not much higher than that at all. That's what reference material on the BoB says and that is borne out by published performance figures on those planes. The LW fighters were instructed to stay as close as possible to the bombers and even the AAF escorts in 1944 were not to get more than 3000' above the bomber stream. 109E escorts had a combat ceiling (1000fpm) of about 27000' but were instructed to stay much closer to their bombers than 7000' to 13000' above. Whether they could even get to 30000' is questionable. And there is no way that a 109E with a 550lb bomb can get to 30000'. Maybe they could fly higher than the bombers, but they aren't getting to 30000' with the extra weight and drag of that bomb. No reference says they got to 30000', just that they flew higher than the bombers. Now maybe a special LW reconnaissance plane could get near 30000' and maybe a Spitfire I tried it's best to intercept, but that was not even a daily occurrence and was still very rare. Very few of my statements are just plain wrong and when they are I admit it.
> 
> ...



The problem is your “facts” are often shown to be incorrect. 

You explicitly stated that the British specified a gas heater and that the P-39D didn’t have it. Those “facts” are both WRONG….and they’re specifically about the P-39, a topic about which you profess to be an expert. If you can’t get stuff like that right, what other pronouncements of yours are incorrect? The British didn’t specify the gas heater…it was standard equipment on the P-39 at the time of the British order.

You keep saying the Brits deliberately added a requirement for “useless” wing 30cals and yet the P-39D also had that armament. Again, your narrative about perfidious Brits has more holes in it than a piece of Swiss cheese.

You stated that the BoB never got near 30K ft and yet when shown multiple sources of evidence you dissemble and try to justify your position by saying that such things didn’t happen often. Bottom line is that BoB sorties at 30K ft DID happen, and again your “facts” were wrong.

This forum is not a popularity contest. We don’t care what points are made so long as they’re adequately justified. Your points are NOT adequately justified and you use your opinions to dismiss actual facts that others present. 

There is no vendetta here against the P-39. As I stated previously, I’ve reevaluated it’s performance based on some of your posts. However, your persistent spouting of conspiracy theories and your dismissive attitude to other perspectives is tiresome to say the least.


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## GrauGeist (Jul 1, 2021)

pbehn said:


> Is that the British sea level or other, the British are known to talk about tides which means the fools dont believe that the sea is level, they also use this sea-unlevelness to refuse to pay up for contracts, FACT!


Quite right - let me be more specific, then:
Was that 30k on a waning moon, and somewhere between afternoon tea and high tea?

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## Thumpalumpacus (Jul 1, 2021)

pbehn said:


> Why were the Americans so stupid as to put a Merlin in a P-51 when they had the answer there already?



This is really the crux of the matter. If us Americans already had the war-winning fighter in hand in Dec 1941, why did we bother with any other designs?

The answer is: the USAAF at the time, meaning its generals, its procurement staff, and its pilots, all believed that better aircraft could be had.

Why did the Brits reject it? They believed better aircraft were already on hand.

The folks who operated it replaced it when they could with better aircraft. That says more than any data sheet ever can about the plane's utility under operational conditions. Compare and contrast that to, say, the A-10, which has survived numerous attempts to replace it. The folks at the pointy end of the spear know a good thing when they see it. They also know a problem-child when they see it.

All the gainsaying from datasheets don't mean s**t from shinola when it comes to the warriors who fly, fight, or benefit from the plane in question. They are the only experts we can really regard, and their expert opinion was that the P-39 should be replaced where possible, and shipped off to the USSR.

They knew the airplane, then, flying and fighting it, better than any self-proclaimed "expert" online.

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## pbehn (Jul 1, 2021)

GrauGeist said:


> Quite right - let me be more specific, then:
> Was that 30k on a waning moon, and somewhere between afternoon tea and high tea?


I think they used a Tiffin correction factor, cross referenced to Wisden batting averages.

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## GrauGeist (Jul 1, 2021)

pbehn said:


> I think they used a Tiffin correction factor, cross referenced to Wisden batting averages.


Ahh...ok.
It's all making much more sense, now

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## wuzak (Jul 1, 2021)

P-39 Expert said:


> Finally "but those better-performing (P-39) variants arrived after other designs were already in service" is the main myth that I am trying to expose. The P-39 was available at the beginning of the U.S. involvement in WWII. And the much improved models with uprated engines (N) were available from the fall of 1942 just as the P-38F/G was entering combat and well before the P-47, P-51B/C/D, F4U and Hellcat entered combat. Performance was on par with the 109G and FW190A and vastly superior to the A6M2, A6M5 and Ki-43. *These are facts as borne out by Wright Field tests* and results from the main users, the Soviets.



Using WWII Aircraft Performance performance tests such as these?



> Report on flight tests of Bell P-39M-3 airplane at the manufacturer's plant.





http://www.wwiiaircraftperformance.org/P-39/P-39M-3_42-4706_FS-M-19-1511-A.pdf






> Report on flight tests of Bell P-39N-1 airplane at the manuacturer's plant.





http://www.wwiiaircraftperformance.org/P-39/P-39N_FS-M-19-1487-A.pdf






> Report on climb and take-off tests of Bell P-39N-1 airplane at the manuacturer's plant.





http://www.wwiiaircraftperformance.org/P-39/P-39N_FS-M-19-1510-A.pdf


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## nuuumannn (Jul 1, 2021)

buffnut453 said:


> Apparently all Brits are liars, cheats and all round dishonest operators.



Well, the Brits _always_ play the baddies in movies...

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## wuzak (Jul 1, 2021)

P-39 Expert said:


> They sure did refuse to pay for the P-38 Lightning equipped as they specified it.



They received 3 Lightning Is.

They tested the first Lightning I they received and found it to be shite. So they said "send no more of this specification".

They still had several hundred Lightning IIs on order.

They received 1, the rest being taken by the USAAF. This is because by the time the Lightning II was getting into production something had happened at Pearl Harbor.


Also, there seems to be some doubt whether turbo were allowed for export when the original French/British orders for the Lightning were placed. 

Also, Also, I imagine that the British paid for aircraft they received. 4 Lightnings in all.

You must remember that when the P-38 and P-39 were ordered by the British neither were anywhere near to production models. The performance promised was nothing more than estimates at that time. And no doubt the contracts had an out clause if the aircraft did not match the specified performance.

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## DerAdlerIstGelandet (Jul 1, 2021)

nuuumannn said:


> Well, the Brits _always_ play the baddies in movies...



I thought that was zee Germans.


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## pbehn (Jul 1, 2021)

wuzak said:


> They received 3 Lightning Is.
> 
> They tested the first Lightning I they received and found it to be shite. So they said "send no more of this specification".
> 
> ...


I just read yesterday that the materials that were needed for turbos were in short supply at the time, so allocation of "turbos" as such may not have been banned for export so much as banned for fighters. Its complicated. What isnt complicated is the discussion of 3 fighters cost. By the time the Lightning II arrived in UK it was part of a mutual agreement for testing and evaluation AFAK and of much more value to the USA than UK, what do you do with one aircraft? What happened to it?


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## pbehn (Jul 1, 2021)

DerAdlerIstGelandet said:


> I thought that was zee Germans.


Dont you watch US crime drama? The criminal is almost always a British actor from RADA (the acting school all rich people send their delinquent kids to). If it isnt a British actor wot dun it, its someone who smokes.

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## pbehn (Jul 1, 2021)

pbehn said:


> Dont you watch US crime drama? The criminal is almost always a British actor from RADA (the acting school all rich people send their delinquent kids to). If it isnt a British actor wot dun it, its someone who smokes.




 DerAdlerIstGelandet
believe it or believe it not, I only had two translators in China, both were self taught and both had noticed the same, they asked me why it was. As if I would know I dont work in the US TV movie industry and have only spent 2 hrs in USA (stop overs in Anchorage)


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## nuuumannn (Jul 1, 2021)

DerAdlerIstGelandet said:


> I thought that was zee Germans.



Only the Nazis, apparently they're as bad as the British! (That was a joke, by the way)

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## special ed (Jul 1, 2021)

Very Inteeeresting.


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## Shortround6 (Jul 1, 2021)

The timing of the P-39 contracts and the P-38 contracts don't work well for the British deliberately screwing things up to get out of the contract story.

As has been pointed out more than once the British took over the French order.

The French were in talks by Feb/March of 1940 if not before, the British were not, at least that I have seen accounts of.
There was a lot of to and fro about what was going to be allowed to be exported and what was not.

From Page 116 of "Cobra, Bell aircraft corporation by Birch Mathews.
" Harry Collins wired Larry Bell on 2 April 1940 confirming the fact that Bell Aircraft could " conduct preliminary conversations with the Anglo-French Purchasing Board concerning export of the* P-39 designed to War Department Specifications.*"
Bolding by me. I interpret this to mean that the items exported cannot deviate too far from the same item/ either purchased by or ordered by the War department.
The US had gotten badly burned in WW I when it declared war and most of it's factories capable of making weapons of war were tooled up for French and British equipment (and ammunition) which the US War Dept. did not want. They were not going to let it happen again. The US turned down all requests by the British to make British designed tanks in the US for instance. The US would sell tanks with a British designed turret but that was as far as they would go.
This is background, take it as you will.


The French sign orders on April 10th and Larry Bell gets a $2 million dollars check, saving Bell aircraft from near bankruptcy. The French and Bell had reached agreement on the detail model specifications in March. This included the wing guns. This is well before the P-39C is completed. The P-39Cs had been ordered in Aug of 1939 but actual construction would not start until the fall of 1940 and first completed plane didn't fly until Jan 1941.

Back to 1940, The Germans attack May 10th, one month after the French order 165 P-39/P-400s.

France signs the Surrender/Armistice papers June 25th.

Britain, as per agreements had taken over ALL outstanding French contracts. By July 10th 1940 a revised specification is agreed to by Bell and the British to include such things as British supplied guns and equipment instead of the French equipment. The revised specification includes 5 more aircraft, total of 170.

On Sept 14th the US Army revises it's contract with Bell for 80 P-39Cs, none which are even close to completion. The first 20 will be completed to the original specification (Aug 1939).
the remaining 60 will get self sealing fuel tanks and be called P-39Ds. This is one day AFTER the Army orders 394 P-39Ds with self sealing tanks, armor and four .30s in the wings.

The British and Bell agree to a new specification on Jan 3rd 1941, still for 170 planes. differences don't seem to be noted?

Next British specification is dated 20th of June 1941 and brings the order to 675 airframes, please note that this is almost 3 months after Lend Lease was signed into Law.
If the British didn't want to pay for 505 P-400s, then don't order them in June of 1941, they were only on the hook for 170 up until then.

The First P-400 flew in April of 1941. Serial number AH570, it was used for general handling trials, the performance trials would be carried out with AH571 which was the extensively modified plane. It first flew at the end of April 1941.

What is somewhat interesting is that three P-39Cs were sent to England, arriving at the beginning of July 1941 as part of lend lease. They were training/familiarization rather than combat. However from Joe Baugher's web site.
"The first of these P-39Cs actually arrived at RAF Colerne on July 3, 1941, followed by the other two the next day. It made its first test flight in England on July 6. However, during trials at Duxford, the performance proved disappointing. Although the test pilots praised the general ease of handling of the aircraft, the maximum speed was a shocking 33 mph lower than that anticipated. The fighter proved to be definitely inferior to the Hurricane and Spitfire in climb rate and ceiling, and the 750-yard takeoff run of the Airacobra excluded its operation from some smaller fighter airfields. There was universal shock and dismay among the RAF personnel. What had gone wrong?"
Remember that this was the P-39C with no armor, no self sealing fuel tanks, no wing guns (but two .30 cal guns in the cowl) No IFF. 

So when did the British specify all the "junk" to get out of the cash contract so they could get free airplanes?

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## Thumpalumpacus (Jul 1, 2021)

nuuumannn said:


> Well, the Brits _always_ play the baddies in movies...



Perfidious Albion!

Would someone smash that trope in the face with a piece of heavy machinery already? It's lazy thinking.


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## Thumpalumpacus (Jul 1, 2021)

wuzak said:


> Also, there seems to be some doubt whether turbo were allowed for export when the original French/British orders for the Lightning were placed.



My understanding is that all turbocharged engines were forbidden for export.

If I'm wrong, I will welcome solid correction.


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## pbehn (Jul 1, 2021)

Shortround6 said:


> What is somewhat interesting is that three P-39Cs were sent to England, arriving at the beginning of July 1941 as part of lend lease. They were training/familiarization rather than combat.


I think the P-39 story changed completely once the Germans invaded Russia on 22 June 1940. A team of Russian experts arrived in UK at sometime in UK to familiarise with the P-39 and although 601 squadron only did a few sorties with the P-39 they didnt officially give them up until the beginning of the next year. The lease lend training and familiarisation scheme being for Russian pilots and engineers for they latest P-39 type being made as far as I can see.


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## DerAdlerIstGelandet (Jul 1, 2021)

nuuumannn said:


> Only the Nazis, apparently they're as bad as the British! (That was a joke, by the way)



Let me see your Paperz.

Achso, you have no Paperz.


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## wuzak (Jul 1, 2021)

pbehn said:


> I think the P-39 story changed completely once the Germans invaded Russia on *22 June 1940*. A team of Russian experts arrived in UK at sometime in UK to familiarise with the P-39 and although 601 squadron only did a few sorties with the P-39 they didnt officially give them up until the beginning of the next year. The lease lend training and familiarisation scheme being for Russian pilots and engineers for they latest P-39 type being made as far as I can see.



You meant 1941?

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## wuzak (Jul 1, 2021)

Thumpalumpacus said:


> My understanding is that all turbocharged engines were forbidden for export.
> 
> If I'm wrong, I will welcome solid correction.



At some point that changed, since the bulk of British P-38 orders were to be the Lightning II, with the turbo. The change in the order from all Lightning Is to 2/3+ Lightning IIs occurred before the Lightning I made it to Britain. Maybe that was the point when turbos were allowed for export?

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## GregP (Jul 1, 2021)

This is WAY past an exercise in futility. It's almost as bad as a P-39!

Maybe I shouldn't have said that ... but, hey, call it what it is.


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## Thumpalumpacus (Jul 2, 2021)

wuzak said:


> At some point that changed, since the bulk of British P-38 orders were to be the Lightning II, with the turbo. The change in the order from all Lightning Is to 2/3+ Lightning IIs occurred before the Lightning I made it to Britain. Maybe that was the point when turbos were allowed for export?



I had no idea turbos were ever cleared for export. I have held the impression that their export was forbidden. If that's wrong, I'm all ears -- school me.

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## wuzak (Jul 2, 2021)

Thumpalumpacus said:


> I had no idea turbos were ever cleared for export. I have held the impression that their export was forbidden. If that's wrong, I'm all ears -- school me.



Well, the RAF received B-17Cs (Fortress I) with turbos in 1941 under Lend Lease.

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## ThomasP (Jul 2, 2021)

The RAF also eventually received over 800x P-47Ds, beginning in 1944.

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## wuzak (Jul 2, 2021)

And the bulk of the order for P-38s were for the turbocharged Lightning II.


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## P-39 Expert (Jul 2, 2021)

Shortround6 said:


> The timing of the P-39 contracts and the P-38 contracts don't work well for the British deliberately screwing things up to get out of the contract story.
> 
> As has been pointed out more than once the British took over the French order.
> 
> ...


The P-39C tested in the US had a top speed of 379mph and climb rate of 3720fpm at sea level, better than either the Spitfire V or Hurricane. It weighed 7075lbs and would have weighed 7150lbs with self sealing tanks, (reduced) armor plate and glass and 120gal internal fuel. Configured as the British wanted with a 20mm cannon it would weigh 7030lbs. The 3 P-39Cs sent to England in July of 1041 must have weighed more possibly equipped with self sealing tanks and armor specified by the British. P-39C production ended in March 1941 and those 3 were sent to England in July, plenty of time to update them. Joe Baugher doesn't list the weights for the 3 P-39Cs sent to England in July. 

The P-400 tested in the US had a top speed of 371mph. Certainly not 400mph but comparable to the Spitfire V.

As far as the "shock and dismay", the British knew that a 7850lb P-39 wouldn't make the performance guarantee, that's why they had them configured that way. They didn't need them after the BoB and didn't want to pay for them.


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## P-39 Expert (Jul 2, 2021)

buffnut453 said:


> For a few posts we had a reasonable discussion but now we’re back to normal. The gas heater was standard equipment on the P-39C that immediately preceded the P-400, AND it was standard equipment on the P-39D1 and D2 which immediately followed the P-400. And yet it was those perfidious Brits who deliberately specified the gas heater to add unnecessary weight to the aircraft.
> 
> Then we have the incredibly dismissive attitude to an official combat report that was filed by the man leading an entire Spitfire squadron on operations at 30K feet. Apparently, that experienced combat veteran was over claiming his altitude….but, as usual, no rationale for such a ridiculous claim is made. He was just incompetent and couldn’t read an altimeter (but he could lead a fighter squadron into combat…and score kills).
> 
> This really is beyond the pale. If any Brit made such a claim about an American pilot, they’d be kicked off the forum. Apparently all Brits are liars, cheats and all round dishonest operators.


Find a few more reports of BoB Spitfires or Hurricanes getting to 30000'. So far you only have the one. A very rare occurrence.


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## Peter Gunn (Jul 2, 2021)

nuuumannn said:


> Well, the Brits _always_ play the baddies in movies...


Or Romans.

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## pbehn (Jul 2, 2021)

P-39 Expert said:


> Find a few more reports of BoB Spitfires or Hurricanes getting to 30000'. So far you only have the one. A very rare occurrence.


How many do you need? Why are you the arbiter of "common occurrence"? You said never, so you detail all the operations and their altitudes, you dont have a group of minions here to jump about at your behest, you were wrong. Most of October 1940 daylight operations in the BoB were high level Jabo attacks with escorts and interceptors going up to and over 30,000 ft. It has already been explained before many times.


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## Peter Gunn (Jul 2, 2021)

pbehn said:


> How many do you need? Why are you the arbiter of "common occurrence"? You said never, so you detail all the operations and their altitudes, you dont have a group of minions here to jump about at your behest, you were wrong. Most of October 1940 daylight operations in the BoB were high level Jabo attacks with escorts and interceptors going up to and over 30,000 ft. * It has already been explained before many times.*


And the mystery swirling around my resorting to snark is finally solved.

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## pbehn (Jul 2, 2021)

Peter Gunn said:


> And the mystery swirling around my resorting to snark is finally solved.


When I posted there were 2,600 sorties he wanted all the specific altitudes. Test reports of Spitfires at 34,000ft are ignored. Pilots reports of encounters are dismissed as "it was Joe Pilot". We now have some pilot credibility scale that seems to say if Chuck Yeager didnt see it it didnt happen.

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## Juha3 (Jul 2, 2021)

P-39 Expert said:


> Find a few more reports of BoB Spitfires or Hurricanes getting to 30000'. So far you only have the one. A very rare occurrence.


A 2nd one, on 12 Oct 1940, Flt Lt Green from No 421 Flight while flying a Spit IIA at 30,000 ft was attacked by Bf 109Es from JG 52 and shot down. Not at 30,000 ft but not much lower, on 15 Oct 1940, Sgt Lee from No 421 Flight while patrolling in a Spit IIA at 27,000 ft, claimed a Bf 109E

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## pbehn (Jul 2, 2021)

From this very forum, the subject of Spitfires and Bf109s commonly being at 30,000ft is now closed.





This Day in the Battle of Britain


I'd say the second photo is the real one. You can see the shadows of the hurricanes on the ground wile in the first pic there are no shadows and something doesn't look quite right where the Hurricane on the left is in front of the buildings..



ww2aircraft.net




Post #269 3 Oct
Massed fighter-bomber formations began very early and, *climbing above 30,000 ft, *they attacked south-east London and Biggin Hill for most of the morning. Some smaller waves in the afternoon again penetrated as far as central London. *Bf109s operated at a high altitude over* south-east England with a mixture of fighter and fighter-bomber variants bombing London before the RAF could react.
Post #276 7 Oct
*Two attacks were flown at a high altitude and with the RAF unable to intercept, *flew unmolested to drop bombs on BBC House, the RAF’s Adastral House, the War Office and Charing Cross Station, along with residential areas in Bermondsey, Lewisham and West Ham. Tower Bridge was attacked at approximately 0900 hours and the hydraulic mains were damaged, and the bridge was out of action.
Post #280 10 Oct
*From 1100 hours raids of 20 to 30 aircraft crossed the Kent coast at high altitude* and reached southern areas of London. These raids were made throughout the day by bomb carrying Bf109s and proved difficult to intercept by fighter Command. Spitfires of RAF No. 92 Sqn had been scrambled from Biggin Hill to patrol at high altitudes in order to meet such raids and succeeded at about 1230 hours when they engaged Bf109s of JG 51 over Kent. Sgt E.T.G.Frith from RAF No. 92 Sqn was badly burned when he baled out of his Spitfire I (X4597) following combat with Bf 109s near Ashford, Kent at 1250 hours. He died from his injuries on the 17 October 1940. The East Ham Memorial Hospital was hit, involving some casualties, and some damage was done to communications and dock-side property.

Post# 281 11 Oct
At 1000 hours two raids of about 30 Bf109s crossed over Kent, of which one was intercepted by Spitfires of RAF No. 603 Squadron scrambled from Hornchurch. Maj. Adolf Galland of Stab/JG 26 claimed a Spitfire near Eastchurch for his 42nd victory. Hastings was attacked twice, at 0644 hours when 14 HE bombs fell in the residential area demolishing four houses, and at 1215 hours when further civil damage was done. Brighton, Eastbourne and Bexhill were also attacked, but only superficial damage resulted.
The last main attack of the day consisting of 65+ aircraft, crossed the Kent coast just after 1500 hours and headed for London. Hurricanes of RAF Nos. 73, 229, 249, 253, 257, 303 and 615 Squadrons along with Spitfires of RAF Nos. 41, 66, 72, 92 and 602 Squadrons were scrambled to intercept the raid. *Although both Hurricanes and Spitfires were dispatched, only the Spitfires were able to reach the altitude of the Messerschmitts and even then were are at a disadvantage with the German fighters still above them.* One formation of German bombers split into two sections with one heading to London and the other to the South-west. The second wave of over 80 came inland over Deal and Dover at 1525 hours. Few contacts were made, targets were not found and slight damage was reported. No 12 Group despatched three Squadrons to assist in meeting this attack.

Post#282 12 Oct *UNITED KINGDOM*:
Many of the raids made on this Friday consisted of bomb carrying Bf109s, which saw the first combat of the day involving Spitfires of RAF No: 72 Squadron, scrambled from Biggin Hill to protect a convoy, at about 0800 hours off Deal. Six bomb carrying Bf 109s crossed the Channel and caused little damage. *Fighters and fighter-bombers continued to use stream tactics, generally at 30,000 to 35,000 ft where they were difficult to counter.* Hptm. Heinz Bretnütz and Oblt. Gerhard Michalski from Stab II./JG 53 each claimed a Spitfire at 0855 hours.

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## buffnut453 (Jul 2, 2021)

P-39 Expert said:


> Find a few more reports of BoB Spitfires or Hurricanes getting to 30000'. So far you only have the one. A very rare occurrence.



I actually found 2 - you’re ignoring the Magee citation - and one of them was for an entire squadron. It took me about 5 mins of googling to find them. I don’t have all my references because I’ve been on a business trip for a week now…so maybe you can do some research yourself and stop trotting out an unsupported opinion? But that would involve trying to learn rather than simply cherry-picking from posts to persist an argument. 

I note you’ve assiduously ignored (again) my other comments so do you accept that the gas heater was a standard fit on the P-39 and wasn’t a special requirement by the Brits?

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## P-39 Expert (Jul 2, 2021)

pbehn said:


> From this very forum, the subject of Spitfires and Bf109s commonly being at 30,000ft is now closed.
> 
> 
> 
> ...


I only see 30000' mentioned once, the rest of the accounts mention high or higher altitude. High or higher means higher than the bombers which came in at 16000-20000'. And you are using this forum as your source?

I don't care what has been posted, a fighter-bomber (109E with a 550lb bomb) will not physically be able to get up to 30000'. Period. Not physically possible. And 35000'? Dreaming.

A large percentage of this battle, indeed most of the attacks after the first of October (the Blitz) were at night. Is the LW going to operate at 30000' at night? Doubtful.

Not saying it never happened, just saying if it did it was extremely rare. And a 109E with a 550lb bomb at 30000'? No way.


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## P-39 Expert (Jul 2, 2021)

buffnut453 said:


> I actually found 2 - you’re ignoring the Magee citation - and one of them was for an entire squadron. It took me about 5 mins of googling to find them. I don’t have all my references because I’ve been on a business trip for a week now…so maybe you can do some research yourself and stop trotting out an unsupported opinion? But that would involve trying to learn rather than simply cherry-picking from posts to persist an argument.
> 
> I note you’ve assiduously ignored (again) my other comments so do you accept that the gas heater was a standard fit on the P-39 and wasn’t a special requirement by the Brits?


No, the gas heater was specified by the British for the Bell model 14 P-400. Subsequent export model 14 (D-1 and D-2) apparently had the gas heater also according to Shortround. I have not seen that. Not saying it's not correct.

But the model 15 P-39D/F and the rest of P-39 production (Model 26-K/L/M/N/Q) had the ducted hot air from the coolant radiator.


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## pbehn (Jul 2, 2021)

P-39 Expert said:


> I only see 30000' mentioned once, the rest of the accounts mention high or higher altitude. High or higher means higher than the bombers which came in at 16000-20000'. And you are using this forum as your source?
> 
> I don't care what has been posted, a fighter-bomber (109E with a 550lb bomb) will not physically be able to get up to 30000'. Period. Not physically possible. And 35000'? Dreaming.
> 
> ...


Well read it again then, I will make it easy for you, the first line in bold and the second to last line in bold, and I have already posted, which is mentioned in the thread at the start, RDF couldnt tell altitude accurately, so if the planes werent actually intercepted (mentioned many times} then all that is known is that it was higher than the interceptors could get in the time they had, the P-39 would have made precisely no interceptions, none, zero, zilch. When will you give up this nonsense? Read it again from start to finish and learn to count above one. Then read the whole thread for the whole of October.

Who are you to say what is possible? Show me the quals? I am only posting about daylight activity, the twin engined bombers were by then mainly working at night, if you read the thread and some books instead of contemplating what you feel you may have some information on the subject not just feelings.

If you disagree with what is posted take it up with the Moderator who posted it 

 Njaco
,you are utterly pathetic.


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## P-39 Expert (Jul 2, 2021)

wuzak said:


> Using WWII Aircraft Performance performance tests such as these?
> 
> 
> 
> ...


Those N tests would be the ones.


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## P-39 Expert (Jul 2, 2021)

pbehn said:


> Well read it again then, I will make it easy for you, the first line in bold and the second to last line in bold, and I have already posted, which is mentioned in the thread at the start, RDF couldnt tell altitude accurately, so if the planes werent actually intercepted (mentioned many times} then all that is known is that it was higher than the interceptors could get in the time they had, the P-39 would have made precisely no interceptions, none, zero, zilch. When will you give up this nonsense? Read it again from start to finish and learn to count above one. Then read the whole thread for the whole of October.


The P-39 was not involved in the BoB. It hadn't even been produced yet. It was not available. Please don't mention the P-39 and the BoB in the same sentence again. Impossible.

The second to last line, as has been explained to you many times before, is a physical impossibility. A 109E with a 550lb bomb can't get to 30000'. Can't be done.

Look, you are never going to be able to prove your position. You've been searching for this for a while now, and have found two references that are pilot accounts. You yourself admit that radar back then couldn't reliably indicate altitude. Any BoB combat at 30000' was a very rare occurrence, if it occurred at all. 

I will never be able to prove that it didn't happen, even though LW bombers topped out at 20000' and the 109E escorts were instructed to stay close to the bombers. Half the battle was at night. there certainly weren't any flights at 30000' at night. And NO fighter bombers at 30000'.

Please continue believing that squadrons of planes fought it out over 30000' all the time. I'll remain very skeptical.


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## pbehn (Jul 2, 2021)

P-39 Expert said:


> The P-39 was not involved in the BoB. It hadn't even been produced yet. It was not available. Please don't mention the P-39 and the BoB in the same sentence again. Impossible.
> 
> The second to last line, as has been explained to you many times before, is a physical impossibility. A 109E with a 550lb bomb can't get to 30000'. Can't be done.
> 
> ...


What is your point, you said that none ever got above 30,000ft now it becomes an issue of whether they had a bomb or not. A Bf 109 with a bomb is a BOMBER. You saying something didnt happen because you dont believe it is not explaining anything. Who are you to explain anything to anyone? You cant count past one and cant be bothered to read a post let alone a book.


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## FLYBOYJ (Jul 2, 2021)

I don't have a dog in this fight, but this was from the book "Dogfight: The Battle of Britain;

P177






P178





P179

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## pbehn (Jul 2, 2021)

FLYBOYJ said:


> I don't have a dog in this fight, but this was from the book "Dogfight: The Battle of Britain;
> 
> P177
> View attachment 630844
> ...


I would normally give a winner emoji for this, but on this thread nothing wins, after all, they are just "joe pilot" recollections.

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## Thumpalumpacus (Jul 2, 2021)

FLYBOYJ said:


> I don't have a dog in this fight, but this was from the book "Dogfight: The Battle of Britain;
> 
> P177
> View attachment 630844
> ...



Oh, come on. You expect that reports from the guys who were there, actually flying the plane, trump an Internet Expert?

Get real.

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## GregP (Jul 2, 2021)

Reference post #2064. There is a flight test in WWIIaircraftperformance on a P-39C dated 22 Sept 1941. The P-39C weighed in at 7,303 lbs, not 7,030 lbs. It apparently made 406 mph at just over 18,000 feet. The power curves were not available on the test day and the data were not corrected to a standard day. Had standard day corrections been applied, then the altitude and the airspeeds would have been reduced. In the notes, it says the aircraft was fitted with smaller-than-standard elevators and rudder and a special fin and stab, so the results were atypical.

I also saw a test where the P-39C was only loaded to some 6,900 lbs, but that was a very short report (1/2 page) and centered on propeller rpm, not on performance testing. Flight tests at less than normal weight are generally not quoted for performance since most military flights WERE loaded to normal weights for a combat mission. If not, then the airplane had either less range, less ammunition / ordnance, or both. The only time you WOULD load to less than normal weight for combat would be for a very short mission, coincidentally just about how most Russian combat flights in P-39s were conducted.

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## P-39 Expert (Jul 2, 2021)

Thumpalumpacus said:


> This is really the crux of the matter. If us Americans already had the war-winning fighter in hand in Dec 1941, why did we bother with any other designs?
> 
> The answer is: the USAAF at the time, meaning its generals, its procurement staff, and its pilots, all believed that better aircraft could be had.
> 
> ...


Agree with the first three. Except the British believed better aircraft than a 7850lb P-400 were on hand. A lighter P-400 would have proven different.

The P-39 prime user, the Soviets, never replaced their P-39s throughout the war. They defeated the LW at all altitudes in all conditions.

The datasheets are the only quantitative way to evaluate airplanes. Expert opinions are just that, opinions. They were quite critical of P-38s, P-40s and P-47s also. And those planes certainly had their drawbacks. Was Chuck Yeager an expert? I would say so.

Planes obviously got better as the war progressed, as they should. More powerful engines, aerodynamic and structural advances. The best prop plane of the war, the Merlin P-51 Mustang didn't see combat until late 1943. What are you going to fight with until then? The P-40 that wouldn't climb above 20000'? The 1943 P-38F/G that was not maneuverable enough to dogfight and couldn't dive from high altitude? The 1943 P-47 that didn't have the range for either Europe or the Pacific? All very serious flaws. The 1943 P-39N could climb faster and was more maneuverable than all three and had about the same range as the P-40 and P-47. And was available in quantity. Ask the Soviet P-39 warrior experts.


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## FLYBOYJ (Jul 2, 2021)

pbehn said:


> I would normally give a winner emoji for this, but on this thread nothing wins, after all, they are just "joe pilot" recollections.


😅 All else aside, I believe that there's an interview Peter Townsend (Duel of Eagles) where he talks about combat over 30K. I think it's also mentioned in the noted book


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## pbehn (Jul 2, 2021)

P-39 Expert said:


> Agree with the first three. Except the British believed better aircraft than a 7850lb P-400 were on hand. A lighter P-400 would have proven different.


Stop dragging the British into your nonsense, the British knew they had a better aircraft in 1938, the also knew the P-400 was a pup as soon as they flew it, thats why they packed them all up and sent them away, under perfoming tripe sold by charlatans, everyone knows it. British aircraft didnt need a camp stove to keep the pilot warm.


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## P-39 Expert (Jul 2, 2021)

FLYBOYJ said:


> I don't have a dog in this fight, but this was from the book "Dogfight: The Battle of Britain;
> 
> P177
> View attachment 630844
> ...


Good work. But, these are still pilot accounts. Mostly 109s diving from reportedly 30000'. One Spitfire's windshield was frozen. Not only almost impossible to get to 30000' but if you did get there you had problems like this. Park's defenders were equally at ease at their optimum height of 27000'? That was the combat ceiling for a Spitfire I per wwiiaircraftperformance. And 27000' isn't 30000'.

What I don't understand is we all pretty much agree that the LW bombers came in at 16000'-20000', right? And the 109Es were required to provide close escort. Close escort is not 10000'-14000' higher than the bombers. All the night fighting, convoy and channel fighting, attacking the airfields, none of that could possibly have been at 30000'. 

We've found five possible instances, less than that for Spitfires, all pilot accounts comparable to victory claims, probably highly exaggerated. It can't be definitively proven that planes did operate at 30000' in the BoB, nor can it be definitively proven that they didn't. All I'm saying is if it did actually happen it was a very rare occurrence. The equipment just wouldn't do it.


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## pbehn (Jul 2, 2021)

FLYBOYJ said:


> 😅 All else aside, I believe that there's an interview Peter Townsend (Duel of Eagles) where he talks about combat over 30K. I think it's also mentioned in the noted book


There are many, I have posted them, you have posted them others have posted the. Njaco has a thread that describes a month of them. Nothing is accepted because only feelings matter, and our P-39 expert feels he cant accept any of it because that would mean the British were justified in not taking the P-39 in 1941. The real issue wasnt the combats that took place but the ones that didnt, because a Bf109 with a bomb and some escorts could take off and climb over British defences before any interceptor could get up could stop them, so standing patrols were started. Almost always if an attack was intercepted the Bf109s dropped their bomb and became a fighter. But when the bombs are dropped why fight? The RAF know that their opponent has only a few minutes over London before he needs to get home, the LW know that if they take any damage that could end their war for absolutely nothing, they certainly werent going to drop down 30,000ft and start straffing the locals. I have read countless accounts of this that said the pilots just looked at each other. As one pilot said "They werent doing any harm at all up there, they could stay as long as they wanted"

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## pbehn (Jul 2, 2021)

P-39 Expert said:


> Good work. But, these are still pilot accounts. Mostly 109s diving from reportedly 30000'. One Spitfire's windshield was frozen. Not only almost impossible to get to 30000' but if you did get there you had problems like this. Park's defenders were equally at ease at their optimum height of 27000'? That was the combat ceiling for a Spitfire I per wwiiaircraftperformance. And 27000' isn't 30000'.
> 
> What I don't understand is we all pretty much agree that the LW bombers came in at 16000'-20000', right? And the 109Es were required to provide close escort. Close escort is not 10000'-14000' higher than the bombers. All the night fighting, convoy and channel fighting, attacking the airfields, none of that could possibly have been at 30000'.
> 
> We've found five possible instances, less than that for Spitfires, all pilot accounts comparable to victory claims, probably highly exaggerated. It can't be definitively proven that planes did operate at 30000' in the BoB, nor can it be definitively proven that they didn't. All I'm saying is if it did actually happen it was a very rare occurrence. The equipment just wouldn't do it.


You agreed that with yourself from your feelings about twin engined bombers, the combat ceiling has a denoted rate of climb that defines it as the COMBAT ceiling, if you are vectored to intercept something higher, you use that rate of climb to get there, until you get there, if you can, because that is your job. In the BoB as stated in the link I posted, Hurricanes just got no where near the fight, Spitfires did sometimes, but on other occasions they were scrambled too late. How long did it take a P-400 to get to 30,000 ft? Being an expert you must know, or will you ignore a question again?


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## Thumpalumpacus (Jul 2, 2021)

P-39 Expert said:


> Expert opinions are just that, opinions.



Their opinions are more valuable than yours. Do you think they didn't read their handbooks or manuals?

Book-learning doesn't work for hunting, flying, or f**king. How many hours do you have in a -39, oh Expert?


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## Thumpalumpacus (Jul 2, 2021)

pbehn said:


> Stop dragging the British into your nonsense, the British knew they had a better aircraft in 1938, the also knew the P-400 was a pup as soon as they flew it, thats why they packed them all up and sent them away, under perfoming tripe sold by charlatans, everyone knows it. British aircraft didnt need a camp stove to keep the pilot warm.



To be fair to him, I was the one who pointed out the Brits knew they had better in the stables, and he was just replying to my point.

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## buffnut453 (Jul 2, 2021)

P-39 Expert said:


> No, the gas heater was specified by the British for the Bell model 14 P-400. Subsequent export model 14 (D-1 and D-2) apparently had the gas heater also according to Shortround. I have not seen that. Not saying it's not correct.
> 
> But the model 15 P-39D/F and the rest of P-39 production (Model 26-K/L/M/N/Q) had the ducted hot air from the coolant radiator.



And here’s a prime example of why this is the Groundhog Day thread. Again, you’re selectively quoting from threads and ignoring details that don’t fit your narrative.

At Post 1937 
S
 Shortround6
noted that the P-39C, D1 and D2 all had the gas heater. I reinforced the point at posts 1987 and 2031.

The P-39C was the model 13 which preceded the model 14 which was associated with both the P-400 and P-39D. The P-39C was NOT an export variant. It was specified by the USAAF. It had the same heater as the P-400.

Please explain how the British specified a useless heater when it was already standard fit for US-specified P-39Cs.

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## pbehn (Jul 2, 2021)

buffnut453 said:


> Please explain how the British specified a useless heater when it was already standard fit for US-specified P-39s.


Did anyone specify them ever? They may have been used but specified means that is a preference. What does a 20mm cannon shell do to a gasoline heater, as compared to a hot air duct?


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## GregP (Jul 2, 2021)

Reference post 2,086.

Hey P-39 Expert, seemingly, NOBODY except you thinks fighter combat at over 30,000 feet was the exclusive purview of bomber escorts. There WAS combat at 30,000 feet and higher during the BOB. Can you not admit this and move on? If you cannot, why should we consider your posts to be anything but rantings from someone who cannot admit facts when they slap you in the face? When you are wrong, admit it and move on. Don't try dissembling and asking everyone else to prove their point. Instead, prove YOUR point with FACTS supported by sources. After all, YOU are the one with a different opinion. So, make your case. I used to do what you are doing, defend regardless of replies. In case everyone missed it, I really don't DO that anymore. Take a tip and follow suit.

Fighters DID get above 30,000 feet every so often, and sometimes managed to get into combat there, whether or not you want to believe it. Arguing over the frequency of same is pointless; you are mistaken that it never happened, plain and simple.

The P-39 was unloved by everyone except the Russians. They loved them because they were getting them free and the P-39 had enough range and performance at low levels to do what they needed ... which was low-level support work including low-level air combat. Nobody else wanted them. Expert or not, you have hitched your username to an airplane that neither the USA nor the UK felt was very good. The USA did field it, but largely due to no alternative being available. Once an airplane (or car, motorcycle, tractor, etc.) has been branded as bad, an improved version has seldom helped rescued the reputation of the product family. Did the Yugo ever get widely accepted? Did the SmartCar? Did the Ford Edsel? Did the P-39?

If you can say "yes," then you are probably reading posts from the Yugo Expert, the SmartCar Expert, or the Edsel Expert and not from normal sources. The P-39 was not worthless, but it also didn't have GOOD performance and wasn't what was needed at ANY time during the war by anyone except the USSR's niche short-range, low-altitude use of it. It WAS a decent squadron hack, and could be used to cool off beer in underwing barrels in a pinch, but that use didn't justify the spare parts logistics required. When they could do so, most US commands got rid of the P-39s as quickly as they could, with no regret, regardless of whether they had 30-cals or 50-cals installed or which heater was being used.

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## SaparotRob (Jul 2, 2021)

There's an Edsel Expert?


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## pbehn (Jul 2, 2021)

Thumpalumpacus said:


> To be fair to him, I was the one who pointed out the Brits knew they had better in the stables, and he was just replying to my point.


This has been going on since P39 Expert first started posting about the P-39, the only points he wont concede are the points concerning the British screwing up the wonderful P-39 by not accepting it, it started long before you were a member here. There is a thread discussing wartime and pre war attitudes to other nations, we have a poster here with the same daft attitudes to people of the same race just born somewhere else, no argument or fact will change his feelings or beliefs.

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## Thumpalumpacus (Jul 2, 2021)

pbehn said:


> This has been going on since P39 Expert first started posting about the P-39, the only points he wont concede are the points concerning the British screwing up the wonderful P-39 by not accepting it, it started long before you were a member here. There is a thread discussing wartime and pre war attitudes to other nations, we have a poster here with the same daft attitudes to people of the same race just born somewhere else, no argument or fact will change his feelings or beliefs.


 I get that, I just thought it fair to point out my own role in this particular instance.

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## Juha3 (Jul 2, 2021)

P-39 Expert said:


> Good work. But, these are still pilot accounts. Mostly 109s diving from reportedly 30000'. One Spitfire's windshield was frozen. Not only almost impossible to get to 30000' but if you did get there you had problems like this. Park's defenders were equally at ease at their optimum height of 27000'? That was the combat ceiling for a Spitfire I per wwiiaircraftperformance. And 27000' isn't 30000'.
> 
> What I don't understand is we all pretty much agree that the LW bombers came in at 16000'-20000', right? And the 109Es were required to provide close escort. Close escort is not 10000'-14000' higher than the bombers. All the night fighting, convoy and channel fighting, attacking the airfields, none of that could possibly have been at 30000'.
> 
> We've found five possible instances, less than that for Spitfires, all pilot accounts comparable to victory claims, probably highly exaggerated. It can't be definitively proven that planes did operate at 30000' in the BoB, nor can it be definitively proven that they didn't. All I'm saying is if it did actually happen it was a very rare occurrence. The equipment just wouldn't do it.


Take another look Spitfire Mk IIA Performance Testing, roc at 30,000 ft 995 Ft/Min.
And read a couple good books on the BoB, some 109s could act as a close escort, some as top covers and some making sweep ahead the bomber formation. And later during the BoB when the LW began to utilize high flying fighter-bombers, they were escorted by other 109s which could fly higher and up-sun.

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## Juha3 (Jul 2, 2021)

And more combats around 30,000 ft, on 25 Oct 1940 No 41 Sqn was ordered to climb to 31,000 ft (it had just received 14 Spit IIAs) they bounced a formation of 30 Bf 109Es which were flying at 27,000 - 28,000 ft. Its B Flight then attacked another 12 109s, which also flew at 28,000 ft.

On 30 Oct the 41 Sqn was ordered to climb to 29,000 ft, the rear guard flew 500 ft above the rest of the sqn. A Flight attacked a German formation of 18 - 21 Bf 109s, which flew 1,500 ft lower. B Flight, ordered act as a top cover, soon joined the fight.

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## Shortround6 (Jul 2, 2021)

pbehn said:


> Did anyone specify them ever? They may have been used but specified means that is a preference. What does a 20mm cannon shell do to a gasoline heater, as compared to a hot air duct?


Gasoline heater is a hot air duct. It draws fuel from the aircraft fuel system. No separate tank. Some A-20s used them, perhaps other combat aircraft. 

My take (opinion) is that the gasoline heater was used on the early P-39s, perhaps the XP-39. perhaps not. At some point somebody in the US figures out that when the guns are fired the cockpit fills up with smoke/fumes from the guns. Somebody figures out that if they duct air from the radiator duct it will be under slight pressure and if they use two inlet ducts from the radiator ducts they can get both hot and cold air without having to use an external scoop(drag) and the slighter higher pressure will help keep the guns fumes out of the cockpit. This apparently is used on the P-39D in the spring of 1941 but for some reason the British don't get the memo and since* 2nd to the last *specification agreement they have with Bell is in Jan 1941 they stick with (or are stuck with) the gasoline heaters. Since they don't even get a P-39C in England until after the last specification agreement is signed they are really stuck with the Gasoline heaters (Bell was getting a commission?  )
Since the D-1 and D-2 are ex RAF machines or machines originally ordered by the British (The D-2 Used different model Allison with 1325hp for take off, it didn't exist as a production engine when the British placed their orders) the exact specifications for the D-2 might be hard to pin down. 

Please note that "exact specifications" may cover things like the size of the shelf the radio sits on or where the holes for the wires are in that shelf. When you are making (or trying to make) hundreds of aircraft per month _everything _is spelled out somewhere.

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## Shortround6 (Jul 2, 2021)

On the subject of the 109 not being able to fly at 30,000ft with a 550lb bomb. 

You have a test showing that?

British Spitfire VB (trop) lost less than 2,000ft of altitude while carrying a 90imp gallon drop tank. Granted it used the Merlin 45. The plane with the drop tank reached 33,500ft and had an estimated service ceiling of 34,500ft. 

However not all 109s in the BoB used the same engine and some were using the DB 601N engine using C3 fuel. Somewhat improved altitude performance compared to the older DB 601 engines.


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## buffnut453 (Jul 2, 2021)

Ok...going back to the "BoB never got close to 30,000ft" nonsense.

I took a quick look at a copy of 92 Sqn's Operations Record Book for the months of September and October. As one would expect, the details are somewhat patchy, and there are many events that have sparse details of the altitudes of the combatants. However, even this cursory glance revealed 13 missions where Sqn pilots reported flying operational sorties in excess of 25,000 ft or encountered enemy aircraft flying at those altitudes. For the record, they are listed below:

3 Sep – Patrol Cardiff 30K ft

9 Sep – Patrol Dungenness 26K ft engaged Me109s, patrol Canterbury 26K ft

11 Sep – Patrol base 28K ft

18 Sep – Southend 30K ft, Folkstone/Dover 27K ft

19 Sep – Patrol Base 30K ft, Patrol Manston 30K ft

20 Sep – Dungenness, 27K ft, attacked by Me109s

27 Sep – Sevenoaks, engagement 18K ft but Me109s layered an estimated 8K ft above

30 Sep – Brighton, 27K ft – sighted 30 x Me109s above, one Me109 claimed, and 15 bombers approx. 10K ft below

20 Oct – East of Tunbridge Wells, patrol 15K ft sighed EA at about 30K ft. Climbed squadron and completed successful engagement. Claimed 1x Me110 shot down

25 Oct – Sevenoaks, two squadrons of Spitfires engaged 70+ Me109s at 26K ft


Were such sorties a daily occurrence? Clearly not, and nobody in the thread has tried to claim that they were. However, I don't think 13 recorded events over a 2-month period is particularly rare. Also note that many of these reports weren't just one or two aircraft, they were whole squadrons or even larger formations. 

The entry for 20 Oct is particularly interesting because the engagement started at 15K ft but the Sqn climbed to 30K ft to effect a successful interception. 

This is just one Spitfire squadron in all of Fighter Command so performance may vary for other squadrons...however, it suggests (to me) that high-altitude intercepts were not uncommon.

I'm sure 

 P-39 Expert
will disagree and continue claiming that these were rare events, or that these records aren't accurate because they're just "ordinary joe" pilots. Of course "rare" is a relative term but, given the growing body of evidence, it suggests to me that his claim about the BoB getting "nowhere near 30,000ft" is entirely bogus.

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## GrauGeist (Jul 2, 2021)

P-39 Expert said:


> Good work. But, these are still pilot accounts. Mostly 109s diving from reportedly 30000'. One Spitfire's windshield was frozen. Not only almost impossible to get to 30000' but if you did get there you had problems like this. Park's defenders were equally at ease at their optimum height of 27000'? That was the combat ceiling for a Spitfire I per wwiiaircraftperformance. And 27000' isn't 30000'.
> 
> What I don't understand is we all pretty much agree that the LW bombers came in at 16000'-20000', right? And the 109Es were required to provide close escort. Close escort is not 10000'-14000' higher than the bombers. All the night fighting, convoy and channel fighting, attacking the airfields, none of that could possibly have been at 30000'.
> 
> We've found five possible instances, less than that for Spitfires, all pilot accounts comparable to victory claims, probably highly exaggerated. It can't be definitively proven that planes did operate at 30000' in the BoB, nor can it be definitively proven that they didn't. All I'm saying is if it did actually happen it was a very rare occurrence. The equipment just wouldn't do it.


God Almighty, will you freakin' stop?

You've been provided several solid accounts to verify the high altitude actions and you dismiss it as a few isolated cases.

At this point, you could be provided every single action report from combat over the UK and you'd still find a lame-ass excuse to weasel out of your flawed position.

Stop while you're ahead and move on to something else, FFS.

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## buffnut453 (Jul 2, 2021)

GrauGeist said:


> God Almighty, will you freakin' stop?
> 
> You've been provided several solid accounts to verify the high altitude actions and you dismiss it as a few isolated cases.
> 
> ...



I'm keen to see how he responds to my last couple of posts. I keep hoping that we can steer this thread back to a more profitable discussion...but I'm not holding my breath. 



 P-39 Expert
is trying to bust a perceived myth but, unfortunately, he's so focused on that goal that he won't listen to any other arguments. Anyone who offers a contrary view is "drinking the kool aid" using old, out-of-date information, and any solid evidence that justifies those contrary views is ignored or downplayed (e.g. intercepts at 30,000ft during the BoB). 

I'm afraid this has all the hallmarks of a conspiracy theory where an individual has "new information" that proves everyone else is wrong, and any contrary views are simply dismissed or ignored. It's a self-justifying echo-chamber with no interest in an actual educated, fact-based debate about the merits or otherwise of the case.

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## GrauGeist (Jul 2, 2021)

I am simply amazed at how hard data is so easily dismissed.

And not just one or two posts providing sound facts, but pages worth.

It's almost as if he's working in concert with that ljadw person, who seems to be a bit more persistent with their own version of history...

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## buffnut453 (Jul 2, 2021)

pbehn said:


> Did anyone specify them ever? They may have been used but specified means that is a preference.



I know...but this whole dive into the rabbit-hole of P-39 heaters derived from the comment 

 P-39 Expert
made that the use of a gas heater was evidence that the British tried to increase the weight of the P-400 unnecessarily, in this case because the P-39 already had sufficient heating capability and didn't need an additional gas heater. 

The whole thrust of my argument is that the gas heater wasn't an additional item specified by the British. It was part of the Bell P-39 design as evidenced by its inclusion in the P-39C, the U.S. variant that immediately preceded the P-400. Hence the British simply adopted an extant design. They didn't ask for anything different when it came to cockpit heating. 

I'm grateful to 
S
 Shortround6
for the details he's uncovered on this particular topic. Alas, I'm not convinced his efforts will put a nail in the coffin of the "great Bell heater conspiracy of 1940".

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## GregP (Jul 2, 2021)

Maybe this is the same guy who was insisting on a "thrust column" some 10 years ago or so ... I forget his username at this point.

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## buffnut453 (Jul 2, 2021)

P-39 Expert said:


> Good work. But, these are still pilot accounts. Mostly 109s diving from reportedly 30000'. One Spitfire's windshield was frozen. Not only almost impossible to get to 30000' but if you did get there you had problems like this. Park's defenders were equally at ease at their optimum height of 27000'? That was the combat ceiling for a Spitfire I per wwiiaircraftperformance. And 27000' isn't 30000'.
> 
> What I don't understand is we all pretty much agree that the LW bombers came in at 16000'-20000', right? And the 109Es were required to provide close escort. Close escort is not 10000'-14000' higher than the bombers. All the night fighting, convoy and channel fighting, attacking the airfields, none of that could possibly have been at 30000'.
> 
> We've found five possible instances, less than that for Spitfires, all pilot accounts comparable to victory claims, probably highly exaggerated. It can't be definitively proven that planes did operate at 30000' in the BoB, nor can it be definitively proven that they didn't. All I'm saying is if it did actually happen it was a very rare occurrence. The equipment just wouldn't do it.



Please see my post #2101 which provides yet more evidence of high-altitude interceptions and operations during the BoB. Also see 
J
 Juha3
posts 2097 and 2098 where ROC for the Spit MkII at 30,000ft was virtually 1000fpm, and provides more examples of high-altitude intercepts during the BoB.

Close escort means you stick around, typically at slower speeds, to protect the bombers. It doesn't necessarily mean you stay close to the altitude of the bombers. Doing so just makes you an additional target to be bounced from above. He who has the height has the battle because altitude (potential energy) can be rapidly turned into kinetic energy. If you're the target at a lower altitude, the only way you can gain kinetic energy is to dive away from the threat...which means the Me109s would abandon the bombers they were trying to protect.

I still take offence at your statement that the pilots reporting these actions were exaggerating their positions. It truly beggars belief that you think a qualified combat pilot can't read an altimeter. At the end of the day, it doesn't really matter if the engagement was at 25K, 28K, 30K or 32K....all were considerably higher than most engagements over the Russian front (per another of your posts where the "Kuban Stairs" top out at 23K), which is where this entire argument originated.


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## BiffF15 (Jul 2, 2021)

UFB.

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## GrauGeist (Jul 2, 2021)

buffnut453 said:


> I still take offence at your statement that the pilots reporting these actions were exaggerating their positions.


If you may recall, in another thread, he dismissed my Uncle's unkind sentiments about the P-39, *which he actually flew*.

So it boils down to ignoring and/or dismissing first-hand accounts if they run contrary to the narrative.

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## buffnut453 (Jul 2, 2021)

GrauGeist said:


> If you may recall, in another thread, he dismissed my Uncle's unkind sentiments about the P-39, *which he actually flew*.
> 
> So it boils down to ignoring and/or dismissing first-hand accounts if they run contrary to the narrative.



Like I said...all the hallmarks of a conspiracy theory.

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## FLYBOYJ (Jul 3, 2021)

P-39 Expert said:


> Good work. But, these are still pilot accounts. Mostly 109s diving from reportedly 30000'. One Spitfire's windshield was frozen. Not only almost impossible to get to 30000' but if you did get there you had problems like this. Park's defenders were equally at ease at their optimum height of 27000'? That was the combat ceiling for a Spitfire I per wwiiaircraftperformance. And 27000' isn't 30000'.
> 
> What I don't understand is we all pretty much agree that the LW bombers came in at 16000'-20000', right? And the 109Es were required to provide close escort. Close escort is not 10000'-14000' higher than the bombers. All the night fighting, convoy and channel fighting, attacking the airfields, none of that could possibly have been at 30000'.
> 
> We've found five possible instances, less than that for Spitfires, all pilot accounts comparable to victory claims, probably highly exaggerated. It can't be definitively proven that planes did operate at 30000' in the BoB, nor can it be definitively proven that they didn't. All I'm saying is if it did actually happen it was a very rare occurrence. The equipment just wouldn't do it.


Pete Townsend was a pretty well known Spitfire pilot during the BoB and I believe in the post war years. He was an ace and fought in many battles over England and the European continent. If you're skeptical of "pilot's accounts" then why believe your wwiiaircraftperformance bible, after all, the folks who flew those test flights were just "pilots" too - some never saw combat.

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## FLYBOYJ (Jul 3, 2021)

Well, I'm going back in the corner...(SMH)

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## FLYBOYJ (Jul 3, 2021)

Urggg... Why do I torture myself. 



https://www.raf.mod.uk/what-we-do/centre-for-air-and-space-power-studies/documents1/air-power-review-vol-18-no-2-battle-of-britain-75th-anniversary-special-edition/



Air Power Review, Battle of Britain Edition P 46 "No 11 Group Instructions to Controllers and Analysis"

There are several transcribed memos from Air Vice-Marshal Park. Interesting reading, here's one...

No 11 GROUP INSTRUCTIONS TO CONTROLLERS No 18
From: Air Officer Commanding, No 11 Group, Royal Air Force
To: Group Controllers and Sector Commanders, for Sector Controllers
Date: 11 September 1940
Engagement of Mass Attacks
During the air fighting of the last week, I have noticed the following deficiencies in our control
by Group and Sectors:
A) Individual Squadrons failing to rendezvous as detailed;
B) Individual Squadrons being detailed to big raids;
C) Pairs of Squadrons being placed on patrol too far forward, too low, resulting in their
being attacked by German high fighter screen;
D) Individual Squadrons being given a rendezvous so far forward as to become engaged
before meeting their paired Squadron;
E) Very high raids of between 100 and 150 fighters being allowed to draw up nearly all
the Group prematurely – the bomb raids then approaching about 45 minutes later
when a number of our Squadrons are on the ground refuelling;
F) A persistent tendency of Group Controllers to delay in detailing pairs of Squadrons that
have reached their height and rendezvous on to individual raids or on to a suitable
patrol line across the line of approach;
G) Failing to check Sectors when they report in error less pilots and aircraft effective than
are reported on the evening state of Squadrons.

FRESH INSTRUCTIONS
Very High Enemy Fighters:

*2. The Spitfire Squadrons of Hornchurch and Biggin Hill are, in clear weather, to be
detailed in pairs to attack the high fighter screen which is normally between 25,000 and
30,000 feet.*
Rendezvous:
3. When the sky is almost completely overcast, Squadrons should rendezvous over an
aerodrome below cloud base, otherwise they should rendezvous high over an aerodrome or
point well in advance of the enemy’s raids, in order not to be dived on while still climbing.
Patrol Lines:
4. Whenever it is not possible to get fairly reliable information about the strength, height
and composition of strong incoming raids, fighter Squadrons must be detailed to short patrol
lines, if necessary two Squadrons very high and two Squadrons between 15,000 and 20,000 ft.
Diversions by Enemy Fighters:
5. If it appears that the first wave of raids are high flying fighters, act as follows:
(i) Detail not less than several pairs of Spitfires to fighter screen;
(ii) Get ample Hurricane Squadrons rendezvoused in pairs in the region of
Sector aerodromes;
(iii) Get Northolt and Tangmere Squadrons to Readiness in despatch as wings of
three Squadrons to intercept the enemy’s second or third wave, which normally
contains bombers.
State of Preparedness:
6. During the coming months there will be a few days in which cloud conditions
are suitable for the enemy to assemble mass attacks covered by high fighter screen.
Whenever these conditions obtain, we must maintain a higher State of Preparedness,
and fresh instructions to this end have been issued.
(Sgd) K R Park
Air Vice-Marshal
Commanding No 11 Group
Royal Air Force

One more...

No 11 GROUP INSTRUCTIONS TO CONTROLLERS No 26
From: Air Officer Commanding, No 11 Group, Royal Air Force
To: Group Controllers and Sector Commanders, for Sector Controllers
Date: 8 October 1940
Height of Fighter Patrols
The following instruction is issued in amplification of para 3 of Instructions to Controllers
No 25.
2. When a Spitfire Squadron is ordered to Readiness Patrol on the Maidstone Line, its
function is to cover the area Biggin Hill-Maidstone-Gravesend, while the other Squadrons
are gaining their height, and protect them from the enemy high Fighter Screen. The form of
attack, which should be adopted on the high enemy fighters is to dive repeatedly on them
and climb up again each time to regain height.
3. The Squadron is not to be ordered to intercept a Raid during the early stages of the
engagement, but the Sector Controller must keep the Squadron Commander informed as
to the height and direction of approaching raids.
4. The object of ordering the Squadron to patrol at 15,000 feet while waiting on the
Patrol Line for Raids to come inland is to conserve oxygen, and to keep the pilots at a
comfortable height.* Pilots must watch this point most carefully, so that they have ample
in hand when they are subsequently ordered to 30,000 feet which is to be done immediately
enemy raids appear to be about to cross our coast.*

And finally on P97 from the chapter "‘Battle of Britain Despatch’ by Air Chief Marshal Hugh Dowding"

"Time-honoured methods of escort were at first employed. A strong Fighter
formation would fly a mile or so behind and above the Bombers. When the Germans found
that our Fighters could deliver a well-timed attack on the Bombers before the Fighters could
intervene, or when our Fighters attacked front ahead or below, each move was met by a
counter-move on the part of the Germans, so that, in September, *Fighter escorts were flying
inside the Bomber formation, others were below, and a series of Fighters stretched upwards
to 30,000 feet or more."*

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## wuzak (Jul 3, 2021)

buffnut453 said:


> I know...but this whole dive into the rabbit-hole of P-39 heaters derived from the comment
> 
> P-39 Expert
> made that the use of a gas heater was evidence that the British tried to increase the weight of the P-400 unnecessarily



About the increasing weight unnecessarily, what is the time line for that?

When did the British specify the extra items? Was it at the same time or after the original order?

What performance did Bell guarantee for the Airacobra I (was to be Caribou I) matching British requirements? Or did the performance guarantee ignore the British requirements and, if so, did Bell neglect to mention the state of the aircraft required to match the guarantee.

When did the British receive their first Airacoba and test it? Did the performance match the guarantee?

When did Lend-Lease com into effect? Was it before or after the "additional items" were added by the British?

Was the Airacobra I fitted with the "useless" wing mounted 0.30" lmgs, or were they fitted with the Browning 0.303", which was the primary weapon of the RAF in the BoB. I believe these are related, but not the same weapon? The Spitfire had 2 wing mounted cannon, which would be superior in firepower to the single 20mm and two synchronised 0.50" hmgs that the expert thinks was sufficient firepower. Why then did the Spitfire continue to carry 4 0.303" mgs as well until 1944 (except a few with 4 20mm cannon)?

Why would the British accept an aircraft that didn't have the equipment that their own fighters had? Items such as self-sealing fuel tanks, armour protection (the P-39's layout may have contributed to it requiring more armour) and IFF? I'm part way through drgondog's book on the P-51B. Reading the sections about the negotiations bewteen the AFPB/BPC and NAA it becomes clear that the same items are being requested for the NA-73.

PS: I am glad that the P-39N of late 1942 had superior performance to the Spitfire V of late 1940.

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## wuzak (Jul 3, 2021)

FLYBOYJ said:


> (Sgd) K R Park
> Air Vice-Marshal
> Commanding No 11 Group
> Royal Air Force



You're quoting Keith Park?

I mean, what would he know about fighters and the Battle Britain?

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## Greg Boeser (Jul 3, 2021)

FlyboyJ,
Park was an administrative hack who clearly neglected to heed the operational capabilities of his charges' equipment, therefore demanding unreasonable and impossible performance from them. No wonder the British lost the battle.

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## P-39 Expert (Jul 3, 2021)

Per Wiki: "From mid September daylight bombing was gradually taken over by Bf109E fighters adapted to take one 250kg (550lb) bomb. They flew at altitudes over 20000'. The raids were intended to carry out precision bombing on military and economic targets, but it was hard to achieve accuracy with the single bomb."

Jeffrey Quill wrote of his combat experience while flying with No. 65 Squadron during this period: "Nearly all of our engagements with 109s took place between 20000' and 25000'."

Most LW raids were at night. No 30000' altitudes there. I continue to maintain that a 109E loaded with a 550lb bomb can't get to 30000' and can't hit anything except the ground. Any combat at 30000' in the BoB was extremely rare. Extremely.


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## pbehn (Jul 3, 2021)

P-39 Expert said:


> You might want to read this: Battle of Britain - Wikipedia
> 
> Per Wiki: "From mid September daylight bombing was gradually taken over by Bf109E fighters adapted to take one 250kg (550lb) bomb. They flew at altitudes over 20000'. The raids were intended to carry out precision bombing on military and economic targets, but it was hard to achieve accuracy with the single bomb."
> 
> Most LW raids were at night. No 30000' altitudes there. I continue to maintain that a 109E loaded with a 550lb bomb can't get to 30000' and can't hit anything except the ground. Any combat at 30000' in the BoB was extremely rare. Extremely.


How does that change anything that is posted? If you are over London and you drop a bomb then the ground you hit is called London which was the whole point, you have also made everyone in London take to an air raid shelter.

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## pbehn (Jul 3, 2021)

FLYBOYJ said:


> Pete Townsend was a pretty well known Spitfire pilot during the BoB and I believe in the post war years. He was an ace and fought in many battles over England and the European continent. If you're skeptical of "pilot's accounts" then why believe your wwiiaircraftperformance bible, after all, the folks who flew those test flights were just "pilots" too - some never saw combat.


Townsend is one of very few Spitfire (or other) pilots who is more famous for doing something else, he was the Meghan Markle of his day, having an affair with the queens sister.

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## Juha3 (Jul 3, 2021)

P-39 Expert said:


> Per Wiki: "From mid September daylight bombing was gradually taken over by Bf109E fighters adapted to take one 250kg (550lb) bomb. They flew at altitudes over 20000'. The raids were intended to carry out precision bombing on military and economic targets, but it was hard to achieve accuracy with the single bomb."
> 
> Jeffrey Quill wrote of his combat experience while flying with No. 65 Squadron during this period: "Nearly all of our engagements with 109s took place between 20000' and 25000'."
> 
> Most LW raids were at night. No 30000' altitudes there. I continue to maintain that a 109E loaded with a 550lb bomb can't get to 30000' and can't hit anything except the ground. Any combat at 30000' in the BoB was extremely rare. Extremely.


If you have a slightest idea what No 11 Group was and where it operated and who Keith Park was, read Flyboyj's message #2,113 and Buffnut453's #2,101 and stop that nonsense.

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## pbehn (Jul 3, 2021)

Jeffrey Quill only spent 19 days as a combat pilot, so he wasnt aware of day to day operations. What he says is true from his experience, but things changed in October. It is also true that Spitfire pilots spent more time on patrols than in combat, even in 11 group.


Jeffrey Quill – Spitfire Test Pilot — Articles | 1940 | people | pre-war | Spitfire prototype



During the Second World War, Quill was in charge of development and production flying, a job that he took very seriously – so seriously that he felt he must obtain first-hand combat experience. He was temporarily released on 5 August 1940 to join No. 65 Squadron at RAF Hornchurch, privately hoping that it would be a permanent appointment. On 16 August he shot down a Messerschmitt Bf 109 and two days later he shared a victory over a Heinkel He 111. His combat days were short-lived because he was recalled after 19 days, but they made Quill all the more determined to make the Spitfire an even better fighting machine.​

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## Milosh (Jul 3, 2021)

It must have been miraculous that British a/c armed with puny .303"s managed to shoot down any Luftwaffe a/c during the BoB.


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## pbehn (Jul 3, 2021)

Milosh said:


> It must have been miraculous that British a/c armed with puny .303"s managed to shoot down any Luftwaffe a/c during the BoB.


A bigger wonder is that the LW retained the same calibre until the end of the war, no wonder they didnt have any aces worth a mention.

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## BiffF15 (Jul 3, 2021)

Gentlemen your patience is astounding. i think the longer this goes on more ”items” will be discovered that you will spend an extraordinary amount of effort on all to no avail.

Good luck.

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## Ascent (Jul 3, 2021)

Sorry, I've lost track. Are we listening to fighter pilots now or not?

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## pbehn (Jul 3, 2021)

BiffF15 said:


> Gentlemen your patience is astounding. i think the longer this goes on more ”items” will be discovered that you will spend an extraordinary amount of effort on all to no avail.
> 
> Good luck.


For myself I now realise why the Spitfire MkIX and Mk XIV were how they were, with rate of climb, service ceiling and top speed being much more important than range. Park and Dowdings eyes will have been more upon the many raids that werent intercepted rather than those that were.

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## buffnut453 (Jul 3, 2021)

P-39 Expert said:


> Per Wiki: "From mid September daylight bombing was gradually taken over by Bf109E fighters adapted to take one 250kg (550lb) bomb. They flew at altitudes over 20000'. The raids were intended to carry out precision bombing on military and economic targets, but it was hard to achieve accuracy with the single bomb."
> 
> Jeffrey Quill wrote of his combat experience while flying with No. 65 Squadron during this period: "Nearly all of our engagements with 109s took place between 20000' and 25000'."
> 
> Most LW raids were at night. No 30000' altitudes there. I continue to maintain that a 109E loaded with a 550lb bomb can't get to 30000' and can't hit anything except the ground. Any combat at 30000' in the BoB was extremely rare. Extremely.



And here you are dissembling again. First you state the BoB got "nowhere near 30,000ft".now you're focusing on combat at 30,000ft. Being charitable, I wonder if this is an artifact of your over-emphasis on test reports and test pilot testimonies, which means you entirely fail to comprehend operational and tactical matters.

Some points regarding your above post:

1. As others have noted, Quill was only in the front line for a short period of time. You criticized others for just having single examples of situations but now you quote just one person, with limited operational/combat experience and no general overview of how the battle was proceeding, and seem to think that's a valid rebuttal. News flash: it isn't.

2. In order for engagements to take place at 25,000ft one or both of the adversaries will typically be above that altitude, usually by a margin of several thousand feet. Per my Post #2107, height is everything in air combat. Neither the defending FC fighters nor any escorting Luftwaffe Me109s would be flying at combat speeds when the fight was initiated. You don't go into combat at cruising speed. The quickest way to gain speed is to dive. Hence a combat at 25,000ft could easily have been initiated at 30,000ft. There are numerous accounts of BoB combats starting at very high altitudes and ending right down on the deck.

3. You are continuing to make the claim that a Me109 with a 550lb bomb could not reach 30,000ft. You may be right...but some evidence would be nice. You keep demanding it of others, so how about stumping up some material yourself instead of continuing to spout opinions. Regardless, you're ignoring the fact that the "bomber" Me109s often had a fighter escort. As noted previously, those fighter escorts would be at a higher altitude, and often many thousands of feet higher, to prevent the escorts being bounced and to give them a tactical advantage in the initial engagement.

4. Regarding "Any combat at 30,000' in the BoB was extremely rare. Extremely." You've been offered evidence of dozens of missions and engagements that were at or about 30,000ft. You have FC senior leaders directing fighters to 30,000ft. You've now had it explained (twice) that altitude controls the battle and just because most combats happened at lower altitudes that does not mean the engagement did not commence very much higher. Again, you're continuing to trot out an opinion (which is funny for person who so prides himself on relying on facts) with not a shred of evidence.

Unconnected with the above post, I also note you are still ignoring my comments about the P-39C and the gas heater. Again, put up or shut up. If the British deliberately specified an unnecessary gas heater for the P-400 show us the evidence. You made the claim now back it up with facts. You say you're big on facts but you seem very reluctant to post many, or to accept facts presented by others.

My overall take-away from this is that you're just trolling. A number of people on this thread have taken the time to provide solid, contemporary evidence, and have tried to explain the flaws in your thinking. In response, you dismiss them with nothing more than your personal opinions and continue to return to the same old tired, debunked, mantras. That's the very epitome of a troll.

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## pbehn (Jul 3, 2021)

Ascent said:


> Sorry, I've lost track. Are we listening to fighter pilots now or not?


Only if the selected quote fits the narrative. What Quill said was true in September 1940, when twin engined bombers were still operational. They took advantage of the same defensive escort "screen" or pretended to be part of it, overtaking the bomber stream and coming out of the front of it, intended to be the first to arrive at London.

From Wiki article on Battle of Britain day 15 Sept 1940 Battle of Britain Day - Wikipedia

"They crossed the coast at Folkestone at 11:36. Fighters from II._Lehrgeschwader 2_ (Demonstration Wing 2) were also to form part of the escort. They flew in advance of the main force to drop 550 lb (250 kg) bombs and then resume their role as fighters."

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## FLYBOYJ (Jul 3, 2021)

Back to the corner...

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## GrauGeist (Jul 3, 2021)

Ascent said:


> Sorry, I've lost track. Are we listening to fighter pilots now or not?


Nope - it seems that their first-hand accounts are deemed "unreliable"...


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## MikeMeech (Jul 3, 2021)

buffnut453 said:


> And here you are dissembling again. First you state the BoB got "nowhere near 30,000ft".now you're focusing on combat at 30,000ft. Being charitable, I wonder if this is an artifact of your over-emphasis on test reports and test pilot testimonies, which means you entirely fail to comprehend operational and tactical matters.
> 
> Some points regarding your above post:
> 
> ...


Hi
The RAF wrote an internal Secret report narrative on the BoB, this was reprinted by CASS in 2000 as 'The Battle of Britain' by T C G James, the following pages may be of interest:












Mike

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## pbehn (Jul 3, 2021)

I dont know what the significance of saying it was a rare occurrence is. Use of upkeep bombs was very rare in fact only used on one night. Plutonium and enriched uranium bombs were rarer still, one of each used. Grand slam and tall boys were a little more common but still statistically as rare as hens teeth. When Park and Dowding got involved in an issue it meant it wasnt rare at all. The LW lost 29 Bf 109s in October but that is a fraction of the number sent because as the day by day record shows most werent intercepted, which is why Park and Dowding were involved.


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## MikeMeech (Jul 3, 2021)

Hi
'Air Power Review' of Summer 2015 (RAF BoB 75th Anniversary edition), had reprints of a number of 'No. 11 Group Instructions to Controllers' some of interest to this subject are below, first part of one dated 11 September 1940:























The RAF at the time certainly thought there was action at height.

Mike

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## Milosh (Jul 3, 2021)

No German a/c had 2 stage engines, just to be picky.

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## buffnut453 (Jul 3, 2021)

Many thanks 
M
 MikeMeech
for those posts. The weight of evidence makes it abundantly clear that Fighter Command was striving to operate in the 20,000-30,000ft range, with height of paramount importance to provide as much tactical advantage as possible. It beggars belief that 

 P-39 Expert
continues to insist that "It can't be definitively proven that planes did operate at 30000' in the BoB."

I feel a General Melchett moment coming on:

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## GregP (Jul 3, 2021)

What is really extremely rare is P-39 Expert learning anything from first-hand reports of combat pilots who were there and who were required to write about their missions as part of squadron procedures.


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## DerAdlerIstGelandet (Jul 3, 2021)

Do I understand this correctly? An internet armchair pilot thinks his opinions are more valuable than pilot reports?


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## buffnut453 (Jul 3, 2021)

DerAdlerIstGelandet said:


> Do I understand this correctly? An internet armchair pilot thinks his opinions are more valuable than pilot reports?



The general thrust of the argument seems to be that, because combat operations aren't suitable for precise, test-regime, measurement, nobody can prove that any aircraft during the BoB operated at 30,000ft. 

This is some serious dissembling given that the whole genesis of this discussion began with 

 P-39 Expert
stating that the air war over the Eastern Front was conducted at the same altitudes as during the Battle of Britain in 1940. The Soviet Kuban Stairs tactic was cited as an example of high-altitude engagements over the Eastern Front, despite the fact that the Kuban Stairs topped out at about 23,000ft. He then stated that aircraft in the BoB "got nowhere near 30,000ft" and, since then, has been repeating his opinion that, if (stressing the IF...he doesn't think aircraft in 1940 COULD get to 30K ft) aircraft got up to 30,000ft, then it was "extremely rare." Of course, that entire argument ignores the fact that there were all sorts of engagements at altitudes above the Kuban Stairs levels, which suggests that the BoB was a DIFFERENT OPERATIONAL ENVIRONMENT than the Eastern Front. However, all that gets ignored, as do any contemporaneous records of BoB operations at 30,000ft because (a) the pilots were exaggerating, and (b) such operations were "extremely rare."

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## pbehn (Jul 3, 2021)

DerAdlerIstGelandet said:


> Do I understand this correctly? An internet armchair pilot thinks his opinions are more valuable than pilot reports?


Not quite, Chuck Yeager's opinion of his trainer trumps any combat or test report by "joe pilot".

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## Glider (Jul 3, 2021)

I think were all missing the most important error. We keep forgetting that the real pilots who flew them, the real engineer's who worked on them and the real designers who did their best to make the most of the aircraft. Are almost as realistic as a flight sim.

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## pbehn (Jul 3, 2021)

Much has been made about patrol heights being much lower than 30,000ft. There were sound reasons for that. Firstly you use less fuel so can patrol longer, the most important issue is they were off the ground. Also being at high altitude isnt good for humans. The "dead zone" for mountaineers is around 26,000ft above this you will eventually die without Oxygen, but even with Oxygen the low air pressure causes problems that can be fatal. Reading Parks instructions you can see he has this in mind along with everything else. Pilots on both sides hated this era of the battle, not least because it made them feel ill. Effects of high altitude on humans - Wikipedia

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## GregP (Jul 3, 2021)

Of course Chuck Yeager liked the P-39.

It was likely the highest-performing aircraft he had flown when he first got into one. Before that, he flew Primary, Basic, and Advanced trainers and then, likely, the P-40. Compared with the above, the P-39 seemed supreme. Of course, his opinion might have changed had he flown a P-38 or a P-51 or a Spitfire before he flew the P-39.

But, that's a "what if" since we know he hadn't flown higher-performing types before he flew a P-39.

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## pbehn (Jul 3, 2021)

GregP said:


> Of course Chuck Yeager liked the P-39.
> 
> It was likely the highest-performing aircraft he had flown when he first got into one. Before that, he flew Primary, Basic, and Advanced trainers and then, likely, the P-40. Compared with the above, the P-39 seemed supreme. Of course, his opinion might have changed had he flown a P-38 or a P-51 or a Spitfire before he flew the P-39.
> 
> But, that's a "what if" since we know he hadn't flown higher=performing types before he flew a P-39.


From what I have seen, when the sound barrier was broken, journalists ran out of sensible questions about breaking the sound barrier an started asking stupid pointed questions about Bell who made the plane he broke the sound barrier in and the P-39 that he trained in.


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## GregP (Jul 3, 2021)

Maybe they SHOULD have asked why the Miles M-52 didn't break the sound barrier first and where the F-86 one-piece tailplane came from. The one-piece stab came from the Miles M-52 and it was 95% complete when the British suddenly ceased work on it and gave the research data to the USA. I'm sure it was all "politics," but I can't prove it.


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## buffnut453 (Jul 3, 2021)

GregP said:


> Maybe they SHOULD have asked why the Miles M-52 didn't break the sound barrier first and where the F-86 one-piece tailplane came from. The one-piece stab came from the Miles M-52 and it was 95% complete when the British suddenly ceased work on it and gave the research data to the USA. I'm sure it was all "politics," but I can't prove it.



Exactly...and since the most prominent Miles product in WW2 was the Master trainer, we wouldn't even be having these arguments. 

Anybody got a time machine I can borrow?


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## Shortround6 (Jul 3, 2021)

Posted back in post #1616. This are dates and weights of the P-400 project gaining weight from Bell records according to Birch Matthews.

date.............................Empty...................useful load...................Gross...........................notes
Feb 1940....................4,524.......................1,325...........................5,849............................1 cannon, two machine guns
March 1940..............4,715.......................1,285............................6,000............................2machine guns added in each wing
May 1940.................5,149........................1,841............................7,000............................wing gun caliber increased
July 1940...................5,383.......................1,974.............................7,350...........................Armour and self-sealing tanks added
Jan 1941....................5,406.......................2,006.............................7,466...........................Minor empty and useful load increases
June 1941.................5,548........................2,087.............................7,635.........................Engine and fixed equipment weight increases
July 1941...................5,550.......................2,087..............................7,637..........................actual weight of Serial number AH 621

Now to splice in some other dates.

date.............................Empty...................useful load...................Gross...........................notes
Feb 1940....................4,524.......................1,325...........................5,849............................1 cannon, two machine guns
March 1940..............4,715.......................1,285............................6,000............................2machine guns added in each wing
April, 1940, French order 165 planes after several weeks (months?) of talks.
May 1940.................5,149........................1,841............................7,000............................wing gun caliber increased
July 1940 work is completed on the British take over of the French order and add 5 planes, 
July 1940...................5,383.......................1,974.............................7,350...........................Armour and self-sealing tanks added
Sept 1940, The US orders the P-39D and changes the P-39C order form 80 planes to 20 Cs and 60 Ds. 
Sept 1940, the first YP-39 is completed
Jan 1941....................5,406.......................2,006.............................7,466...........................Minor empty and useful load increases
Jan 1941, First P-39C is completed
Jan 1941, The British and Bell agree on changes to the P-400 specification. 
March 1941The US passes the lend Lease act. 
*APRIL 1940, P-400 AH 571 flies, the modified one that just barely passes the speed test.*
June 1941.................5,548........................2,087.............................7,635.........................Engine and fixed equipment weight increases
July 1941...................5,550.......................2,087..............................7,637..........................actual weight of Serial number AH 621
July 1941The British and Bell agree to the last modification of the P-400 specification. and order 505 additional planes. 
July 1941, the 3 lend lease P-39Cs show up in England for familiarization before the the production P-400s show up. 
July 1941, end of July the first production P-400s show up in England. 

Now who knew what and when???????
British don't seem to have ordered the "heater" unless there is direct evidence they did so. the French order the four wing guns. 
The British just went along, or didn't have them taken out. 
By Sept 1940 the US is going along with the four wing guns and going along with the armor and self sealing tanks. 

So when did the British make the changes so they could get out of the contract and get the planes free with lend lease????
Jan is too soon as lend lease doesn't exist yet. July is too late as why bother to order 500 planes with specifications you are trying to screw up???

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## pbehn (Jul 3, 2021)

GregP said:


> Maybe they SHOULD have asked why the Miles M-52 didn't break the sound barrier first and where the F-86 one-piece tailplane came from. The one-piece stab came from the Miles M-52 and it was 95% complete when the British suddenly ceased work on it and gave the research data to the USA. I'm sure it was all "politics," but I can't prove it.


It was an agreement going back to the start of lend lease, if by "one piece tailplane" you mean where the rear wings dont have elevators but the whole thing moves, this was tried out on Spitfires, so the UK were bound by contract to share the information.


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## buffnut453 (Jul 3, 2021)

Shortround6 said:


> Posted back in post #1616. This are dates and weights of the P-400 project gaining weight from Bell records according to Birch Matthews.
> 
> date.............................Empty...................useful load...................Gross...........................notes
> Feb 1940....................4,524.......................1,325...........................5,849............................1 cannon, two machine guns
> ...



Thanks for posting these details SR6. I'm intrigued by the 1,000 lb addition between March and May 1940 due to "wing gun caliber increased." I wonder what the nature of that change might be....going from 30 cal to .303 perhaps? Regardless, it was a BIG increase in weight.


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## Glider (Jul 3, 2021)

pbehn said:


> It was an agreement going back to the start of lend lease, if by "one piece tailplane" you mean where the rear wings dont have elevators but the whole thing moves, this was tried out on Spitfires, so the UK were bound by contract to share the information.


I believe that the actual agreement was that both parties shared information but it was only one way in reality

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## pbehn (Jul 3, 2021)

buffnut453 said:


> Thanks for posting these details SR6. I'm intrigued by the 1,000 lb addition between March and May 1940 due to "wing gun caliber increased." I wonder what the nature of that change might be....going from 30 cal to .303 perhaps? Regardless, it was a BIG increase in weight.


I believe the British specified 900lbs of unsalted tea to be installed in the cockpit.

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## Glider (Jul 3, 2021)

pbehn said:


> I believe the British specified 900lbs of unsalted tea to be installed in the cockpit.


Much better for morale than a paraffin heater


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## pbehn (Jul 3, 2021)

Glider said:


> Much better for morale than a paraffin heater


And it weighs more so the contract can be cancelled, a real win-win.

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## Shortround6 (Jul 3, 2021)

The Manuals for the P-39C and P-38D-1 have some interesting details.


buffnut453 said:


> Thanks for posting these details SR6. I'm intrigued by the 1,000 lb addition between March and May 1940 due to "wing gun caliber increased." I wonder what the nature of that change might be....going from 30 cal to .303 perhaps? Regardless, it was a BIG increase in weight.


Well, the caliber increase was going from the French 7.5mm machine guns to the British 7.7mm machine guns. Obviously something else was going on.


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## buffnut453 (Jul 3, 2021)

Actually, adding 350lb for armour and self-sealing tanks doesn't seem like an exorbitant amount. It seems like the early Spits added about 250lb so, yes, the P-400, did have more weight added but I'm not sure 100lb would massively change performance. It's certainly not enough to cause the contract to be cancelled due to poor performance.


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## Thumpalumpacus (Jul 3, 2021)

DerAdlerIstGelandet said:


> Do I understand this correctly? An internet armchair pilot thinks his opinions are more valuable than pilot reports?



Doenitz is a moron too, apparently.

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## pbehn (Jul 3, 2021)

buffnut453 said:


> Actually, adding 350lb for armour and self-sealing tanks doesn't seem like an exorbitant amount. It seems like the early Spits added about 250lb so, yes, the P-400, did have more weight added but I'm not sure 100lb would massively change performance. It's certainly not enough to cause the contract to be cancelled due to poor performance.


In 1940 the British added a variable pitch prop then a constant speed prop plus they added armour and started using 100 octane fuel. The net result was improved performance. In terms of weight the different props were heavier and the added pilot armour helped adjust the CoG. The Spitfire doubled in weight in its service life, the only thing I have seen discussing weight being an issue on a Spitfire was with the use of 2 cannon + mgs as against 4 cannon, but that was to do with performance at extreme altitude. In all other cases like adding bombs or slipper tanks or whatever it was understood that the more stuff you carry the more you affect performance.


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## GrauGeist (Jul 3, 2021)

Thumpalumpacus said:


> Doenitz is a moron too, apparently.


Aparently, so was Von Rundstedt, Churchill and Guiderian.

So he's in good company.

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## Thumpalumpacus (Jul 3, 2021)

pbehn said:


> I believe the British specified 900lbs of unsalted tea to be installed in the cockpit.



That's a deal-breaker, fo sho.



GrauGeist said:


> Aparently, so was Von Rundstedt, Churchill and Guiderian.
> 
> So he's in good company.



It's wonderful how many experts one finds online.

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## pbehn (Jul 3, 2021)

GrauGeist said:


> Aparently, so was Von Rundstedt, Churchill and Guiderian.
> 
> So he's in good company.


The stuff Park and Dowding came out with would make any modern expert cringe, Spitfires at 30,000ft how ridiculous.


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## Thumpalumpacus (Jul 3, 2021)

pbehn said:


> The stuff Park and Dowding came out with would make any modern expert cringe, Spitfires at 30,000ft how ridiculous.



Yabut with how much tea aboard? The world wonders.

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## pbehn (Jul 3, 2021)

Thumpalumpacus said:


> Yabut with how much tea aboard? The world wonders.


Unsalted tea was freely available in UK, this is how the P-39 was hobbled from the start.

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## GrauGeist (Jul 3, 2021)

Thumpalumpacus said:


> Yabut with how much tea aboard? The world wonders.


Is it entirely possible that those Stewart-Warner heaters were in fact, tea warmers?

If Galland could have a cigar lighter in his cockpit, than why not?

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## buffnut453 (Jul 3, 2021)

GrauGeist said:


> Is it entirely possible that those Stewart-Warner heaters were in fact, tea warmers?
> 
> If Galland could have a cigar lighter in his cockpit, than why not?



Tea WARMER? Sacrilege…SACRILEGE I say!!! Her Majesty’s Royal Air Force has specified water boilers in all long-range aircraft since, I believe, the 1920s for the making of said life-saving beverage. Warming up tea is just plain WRONG on SO many levels!!!

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## Thumpalumpacus (Jul 3, 2021)

pbehn said:


> Unsalted tea was freely available in UK, this is how the P-39 was hobbled from the start.



I blame the East India Company!


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## Thumpalumpacus (Jul 3, 2021)

buffnut453 said:


> Tea WARMER? Sacrilege…SACRILEGE I say!!! Her Majesty’s Royal Air Force has specified water boilers in all long-range aircraft since, I believe, the 1920s for the making of said life-saving beverage. Warming up tea is just plain WRONG on SO many levels!!!



I'm guessing a microwave is not in the equation.


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## Shortround6 (Jul 3, 2021)

The Manuals for the P-39C and P-38D-1 have some interesting details.
From the weight data page of the P-39C Manual and the weight and balance chart of the P-39D-1 manual, they do not have the same format. 

Airplane......................................................................P-39C..........................................................P-39D-1 clean..........P-39D-1 with drop tank
weight empty.........................................................5016lbs*......................................................5599lbs.........................5599lbs
Tactical items
Guns
37mm..........................................................................205lbs........................................................-------................................
20mm..........................................................................-------.........................................................131lbs...............................
Two .50 cal.................................................................128lbs..........................................................139lbs.............................
two .30 cal..................................................................41.6lbs......................................................--------.............................
Four .30 cal.................................................................-------........................................................95lbs................................
Misc, equip, for guns..............................................74lbs.......................................................... 5lbs..................................

Photographic............................................................------..........................................................8lbs...................................
Oxygen.........................................................................20lbs..........................................................8lbs..................................
Pyrotechnics..............................................................------.........................................................10lbs.................................
Radio......................................................................included in empty weight..........................129lbs............................
Armor plate & Glass...............................................131lbs..........................................................248lbs..............................
Pilot...............................................................................160lbs..........................................................160lbs............................
oil.....................................................................................71lbs.............................................................88lbs............................

tactical weight empty................................................5667lbs.....................................................6618lbs...........................6618lbs

Fuel, internal............................................................624lbs (104 US gal).................................720lbs (120 US gal) 
Full internal fuel......................................................1020lbs.........................................................720lbs
fuel external........................................................................................................................................----......................................450lbs
tank weight........................................................................................................................................-----........................................71lbs
extra oil.........................................................................35lbs............................................................-----.......................................included above in tank weight
ammunition.................................................................215lbs..........................................................421lbs..................................

Ballast weights............................................................-----...................................................................88lbs...............................70lbs7857lbs

Gross weight. .............................................................6684.5lbs....................................................7857lbs...............................8368lbs

The Manual for the P-39C is dated Feb 15th 1941 and there are some later revisions. The revision for the weight page is dated 3-20-41. 

On page 21 of the manual paragraph, f.
Load factors, -- The design standards for all previous pursuit airplanes in the service have been for a design load (maximum expected load) of 8.0 positive and 4.0 negative load factors. This airplane is built for a design load of 7.5 positive and 3.75 negative load factors. 

The top speed is calculated as 391mph at 15000ft, _however_ there is an asterisk and the note below says that "temporary restrictions of engine operation prohibit the attainment of these values." 

On the P-39D-1s there is very little explaination of the ballast weights, There are five 17.5 lb weights listed with locations of "Each 2 forward, 2 cent, 1 aft", But doesn't say where any of those locations are (all in gun bay or spread throughout the plane?) when carrying the drop tank or bomb one weight is taken out but so far it doesn't say which one. 

It appears that a lot of the weight on the P-39C in the misc equip for guns catagory was either lumped in with guns themselves or put in another catagory. The guns did not get heavier in later aircraft.

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## FLYBOYJ (Jul 3, 2021)

As far as the unsubstantiated claim of the British wanting to get out of their P-39 contract by adding equipment and weight to the aircraft, I caught this tonight when browsing on the P-38 page on Wiki. I left the citation notes in.

_ By June 1941, the War Ministry had cause to reconsider their earlier aircraft specifications based on experience gathered in the Battle of Britain and The Blitz.[63]​ British displeasure with the Lockheed order came to the fore in July, and on 5 August 1941 they modified the contract such that 143 aircraft would be delivered as previously ordered, to be known as "Lightning (Mark) I," and 524 would be upgraded to US-standard P-38E specifications with a top speed of 415 mph (668 km/h) at 20,000 ft (6,100 m) guaranteed, to be called "Lightning II" for British service.[63]​ Later that summer an RAF test pilot reported back from Burbank with a poor assessment of the "tail flutter" situation, and the British cancelled all but three of the 143 Lightning Is.[63]​ *As a loss of approximately US$15M was involved, Lockheed reviewed their contracts and decided to hold the British to the original order. Negotiations grew bitter and stalled.[63]​ Everything changed after the 7 December 1941 attack on Pearl Harbor after which the United States government seized some 40 of the Model 322s for West Coast defense;[64]​ subsequently all British Lightnings were delivered to the USAAF starting in January 1942. The USAAF lent the RAF three of the aircraft, which were delivered by sea in March 1942[65]​ and were test flown no earlier than May[66]​ at Cunliffe-Owen Aircraft Swaythling, the Aeroplane and Armament Experimental Establishment and the Royal Aircraft Establishment.[63]​ The A&AEE example was unarmed, lacked turbochargers and restricted to 300 mph (480 km/h); though the undercarriage was praised and flight on one engine described as comfortable.[67]​ *These three were subsequently returned to the USAAF; one in December 1942 and the others in July 1943.[65]​ Of the remaining 140 Lightning Is, 19 were not modified and were designated by the USAAF as *RP-322-I* ('R' for 'Restricted', because non-counter-rotating propellers were considered more dangerous on takeoff), while 121 were converted to non-turbo-supercharged counter-rotating V-1710F-2 engines and designated *P-322-II*. All 121 were used as advanced trainers; a few were still serving that role in 1945.[66]​ A few RP-322s were later used as test modification platforms such as for smoke-laying canisters. The RP-322 was a fairly fast aircraft below 16,000 ft (4,900 m) and well-behaved as a trainer_

I think most of this came from Bodie's book _The Lockheed P-38 Lightning: The Definitive Story of Lockheed's P-38 Fighter_


I think if what our "expert" says was really true, Bell "would have" followed suit. Maybe Lockheed had better Lawyers?

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## P-39 Expert (Jul 4, 2021)

Shortround6 said:


> The Manuals for the P-39C and P-38D-1 have some interesting details.
> From the weight data page of the P-39C Manual and the weight and balance chart of the P-39D-1 manual, they do not have the same format.
> 
> Airplane......................................................................P-39C..........................................................P-39D-1 clean..........P-39D-1 with drop tank
> ...


Excellent work Short. So the P-39C had 131lbs of armor plate/glass. I knew it had the armor glass front and back from AHT, but didn't know it also had some armor plate. The 37mm cannon appears a little light, in the later P-39s it is listed at 238/240lbs. Extra weight is probably in "misc. equipment, for guns" 74lbs. Later models list that as "armament provisions", which I think means gun mounts, chargers, heaters and ammunition boxes.

The D-1 (for export) was a virtual copy of the P-400 with the 20mm cannon. 7850lbs gross weight was just too heavy to be a competitive fighter considering contemporary Spitfire V weighed 6600lbs and 109F weighed 6000lbs and both had more powerful engines. Delete the extra armor plate 117lbs, 30cals with ammo 355lbs and the radio 129lbs (I believe that was the IFF radio which wouldn't be needed in NG in 1942) and it weighs 7250lbs. I think it would have made a big difference in performance, especially in climb.


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## wuzak (Jul 4, 2021)

P-39 Expert said:


> The D-1 (for export) was a virtual copy of the P-400 with the 20mm cannon. 7850lbs gross weight was just too heavy to be a competitive fighter considering contemporary Spitfire V weighed 6600lbs and 109F weighed 6000lbs and both had more powerful engines. Delete the extra armor plate 117lbs, 30cals with ammo 355lbs and the radio 129lbs (I believe that was the IFF radio which wouldn't be needed in NG in 1942) and it weighs 7250lbs. I think it would have made a big difference in performance, especially in climb.



Why do you have the fascination with comparing the weight of the P-39 with two aircraft that were fundamentally lighter?

Why do you compare the P-39 to two, at that time, purely ETO fighters when you talk about its use in New Guinea for one moment in time?

Why do you think the IFF is a) not needed and b) weighs 130lbs? I thought the weight thing was dispelled a 100 pages ago. Also, what other US aircraft are in the region at that time, and did they have IFF?

Why do you think the extra 100-odd pounds of armour plate was not necessary? I know you have a bug up your arse about the nose armour and believing it unnecessary and that other aircraft didn't have that - mainly because other aircraft didn't have a remote gearbox and weren't nearly as tricky to prevent the CoG getting too far rearwards.

If you remove the wing guns will you have enough firepower and rate of fire to get hits on enemy aircraft? Considering that the enemy is more manoeuvrable and the P-39 hasn't much endurance.

The Spitfire had 6 guns - 2 x 20mm and 4 x 0.303".

The Bf 109 had 3 guns - 1 x 20mm (or 15mm) and 2 x 7.92mm. The F-4 could be fitted with an additional 2 x 20mm in under wing gondalas. The Bf 109 F1/2 with 3 guns was considered to have a light armament.

Yet, you propose a similar armament for the P-39 - albeit with heavier secondary weapons (the 0.5" mgs, considering that the aircraft was built around having a cannon firing through the hub, the cannon would surely be its primary weapon?).


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## Milosh (Jul 4, 2021)

Because Wuzak the more erroneous and useless info that can be spewed, the more confusing it becomes for those to comment on the nonsense spewed.


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## Glider (Jul 4, 2021)

Since when has logic had any place in the thread. Personally I like the idea of taking out the radio. I am so confident that this would have not gone down well in the combat units

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## pbehn (Jul 4, 2021)

Glider said:


> Since when has logic had any place in the thread. Personally I like the idea of taking out the radio. I am so confident that this would have not gone down well in the combat units


Take out any instrument or device that wasnt in the Wright flyer, obviously not needed.


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## Glider (Jul 4, 2021)

pbehn said:


> Take out any instrument or device that wasnt in the Wright flyer, obviously not needed.


Your so right and there plenty of room to drop in the merlin 61, no armour to remove, no IFF to worry about. By the logic of the thread I reckon your on to a winner.


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## P-39 Expert (Jul 4, 2021)

wuzak said:


> Why do you have the fascination with comparing the weight of the P-39 with two aircraft that were fundamentally lighter?
> 
> Why do you compare the P-39 to two, at that time, purely ETO fighters when you talk about its use in New Guinea for one moment in time?
> 
> ...


Why do you care? Why do you feel compelled to reply to my every post? ALL this has been posted on here lots of times, hence the groundhog theme.


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## GregP (Jul 4, 2021)

Why do you persist with the P-39 fixation? A large part of what you have claimed for the P-39 has been shown to be incorrect, and everyone is pretty sick of P-39s. If you magically went away (and I didn't suggest that), I doubt if anyone would mention P-39s for the next 5 years or more, just out of relief to be done with it.

Let it go, PLEASE. Nobody cares, but it is getting hard to ignore claims that aren't true. You ask why Wuzak, one of our long-time knowledgeable posters, retorts? He's trying his best to politically ask you to desist with the P-39 stuff. I'm not very political. There are 1,000 other WWII airplanes that are being neglected, and the P-39 doesn't deserve the attention it is getting.

This isn't personal against YOU; we're just sick of the P-39. Completely. Why don't you switch over to something like the Ha 139? It wasn't a fighter, but thankfully isn't a P-39, either, and would be a welcome diversion from continuous P-39 trivia, much of which is incorrect again and again and again and ... well, you get it, or you really SHOULD get it. We're on page 109 ... largely about the P-39. C'mon, enough is enough, isn't it?

Cheers.

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## SaparotRob (Jul 4, 2021)

With that said this was a highly educational thread for me. Especially the simple explanation of C.O.G. issues using paper airplanes.

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## P-39 Expert (Jul 4, 2021)

MikeMeech said:


> Hi
> The RAF wrote an internal Secret report narrative on the BoB, this was reprinted by CASS in 2000 as 'The Battle of Britain' by T C G James, the following pages may be of interest:
> View attachment 630921
> 
> ...


Hmmm. "Neither type (MkII Spitfires and Hurricanes) promised to be a satisfactory aircraft at over 25000'." And "the 109E with a 550lb bomb had a ceiling of 25000' at most." "Generally only squadrons that were already airborne had a chance to close with the enemy (at 30000')." "The function of these squadrons was not to intercept as soon as possible but to cover those squadrons from London who were still gaining height." Sounds to me like the British fighters had a very hard time over 25000' and the bomb carrying 109Es could not get over 25000'. Lots of talk about ordering the British fighters to 30000' but also very hard for them to get there. This was all only during the last month of the BoB (October). 

I will give you that the 109E apparently could cruise at 30000' but both British fighters had a very difficult time getting over 25000'.

And a bomb-laden 109E could not get over 25000'.

Why would the British even worry about 109Es at those heights? The 109E bombers couldn't hit anything with any accuracy from that altitude so they were doing minimal if any damage. The LW was just trying to lure the British up to those heights for combat. The goal of the British interceptors was to destroy enemy bombers, not chase after fighters.

I still don't see much fighting at 30000' and nothing over that height. And for absolutely sure no 109E bombers were at that height.


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## pbehn (Jul 4, 2021)

Who says the bomb carrying Bf109s only carried a 250Kg bomb? I have read on this thread that they also carried a 125Kg bomb, that wouldnt be because they had run out of the larger ones, but to get higher There were also Jabo Bf109s made to carry up to 4 x 110lb bombs. They dont have to hit anything accurately, they just need to make a lot of bangs all day to keep London in the air raid shelters, this has been said before and all the nonsense about planes not getting to 30,000ft has too. When Park and Dowding addressed the issue you can be sure it was an issue. There is plenty of stuff about planes over 30,000ft if you choose to ignore or refuse to read it that is your issue. It just looks like weird denial in the face of obvious facts to me.

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## pbehn (Jul 4, 2021)

SaparotRob said:


> With that said this was a highly educational thread for me. Especially the simple explanation of C.O.G. issues using paper airplanes.


Me too, I wasnt aware how many planes were coming in at 30,000ft until some recent posts, it was a real headache for Dowding Park and everyone in London.

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## FLYBOYJ (Jul 4, 2021)

P-39 Expert said:


> *Why would the British even worry about 109Es at those heights? The 109E bombers couldn't hit anything with any accuracy from that altitude so they were doing minimal if any damage. * The LW was just trying to lure the British up to those heights for combat. The goal of the British interceptors was to destroy enemy bombers, not chase after fighters.


Why? - BEACUSE IT THE ENEMY, LOL! And during that part of the war, aside from destroying the UK's ability to wage war, Hitler wanted to diminish the British people's determination to fight. Lobbing bombs over a large population area, especially at night was the perfect way to do this

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## pbehn (Jul 4, 2021)

FLYBOYJ said:


> Why? - BEACUSE IT THE ENEMY, LOL! And during that part of the war, aside from destroying the UK's ability to wage war, Hitler wanted to diminish the British people's determination to fight. Lobbing bombs over a large population area, especially at night was the perfect way to do this


Goering was also involved. Since the twin engined bombers were increasingly used at night, his thinking for fighter pilots was "since you couldnt protect the bombers, you can drop the bombs yourself".

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## buffnut453 (Jul 4, 2021)

P-39 Expert said:


> Hmmm. "Neither type (MkII Spitfires and Hurricanes) promised to be a satisfactory aircraft at over 25000'." And "the 109E with a 550lb bomb had a ceiling of 25000' at most." "Generally only squadrons that were already airborne had a chance to close with the enemy (at 30000')." "The function of these squadrons was not to intercept as soon as possible but to cover those squadrons from London who were still gaining height." Sounds to me like the British fighters had a very hard time over 25000' and the bomb carrying 109Es could not get over 25000'. Lots of talk about ordering the British fighters to 30000' but also very hard for them to get there. This was all only during the last month of the BoB (October).
> 
> I will give you that the 109E apparently could cruise at 30000' but both British fighters had a very difficult time getting over 25000'.
> 
> ...



Sheesh...you really are the master of cherry-picking information and twisting it to suit your agenda while ignoring anything that contradicts you. Some selected quotes from you:

_*Sounds to me like the British fighters had a very hard time over 25000'...both British fighters had a very difficult time getting over 25000'. *_ Please define "very hard time" or "very difficult time". You seem to imply that the Spitfire and Hurricane couldn't get up to those altitudes, despite the body of evidence that has been thrown at you, including official test reports, that show that they could. The statement said that the Spitfire and Hurricane of 1940 weren't satisfactory above 25,000ft. That does NOT mean they struggled to climb above that altitude. It simply means that they were lacking in capability to deal adequately with the threat, which is precisely why Spitfire development continued and the operational altitude progressively increased throughout its lifetime. However, as has been shown multiple times, the Spitfire in particular conducted many operations in the range 25-30,000ft during the BoB.

_*And a bomb-laden 109E could not get over 25000'.*_ Great, but what about the escorting Me109 fighters? Again, the full report talks about how the Luftwaffe sent large numbers of fighters, operating above the Me109 bombers as both close escorts and in advanced fighter sweeps to engage the RAF fighters. Remember that the Luftwaffe was trying to gain air superiority. The only way to do that was to destroy Fighter Command. The Me109 bombers were largely just a nuisance effort to get the RAF committed to the fight in hopes that more Hurricanes and Spitfires could be shot down.

_*Why would the British even worry about 109Es at those heights? The 109E bombers couldn't hit anything with any accuracy from that altitude so they were doing minimal if any damage.*_ Because role of Fighter Command was defence of UK airspace. Your laissez-faire attitude regarding "minimal damage" completely ignores the fact that any bomb dropped over a major British town or city would result in civilian casualties. Fighter Command was expressly charged with preventing such attacks to minimize civilian casualties.

_*The goal of the British interceptors was to destroy enemy bombers, not chase after fighters. *_ And this has been explained multiple times before. Yes, the RAF wanted to destroy the bombers. However, focusing exclusively on the bombers and ignoring the escorting Luftwaffe fighters would have resulted in unsustainable casualties. Again, if you let the adversary have the altitude in an air battle, you give him the advantage. If the RAF ignored the Luftwaffe escort, it would cede the tactical advantage and abrogate Fighter Command's responsibility to defend UK airspace.

*This was all only during the last month of the BoB (October). *Please see my post 2101. How many sorties above 25,000ft were in September and how many in October? Yet again you're making a sweeping statement that is inaccurate, ignoring all evidence that doesn't fit your narrative.

*I still don't see much fighting at 30000' and nothing over that height. And for absolutely sure no 109E bombers were at that height. *Because you're deliberately ignoring the evidence that's been presented. This whole part of the discussion grew out of yet another of your incorrect assertions where you stated there was no difference between air combat in Eastern Europe vs Western Europe prior to 1943 (your post 1899). Other contributors have provided abundant evidence that the BoB fight was very different from that over Russia, not least in terms of the altitude of operations. Since that information doesn't fit your preconceived notions, you are ignoring it and arguing the toss about nit-picking details. Bottom line: over Russia, the fight was typically below 23,000ft while in the BoB many of the engagements started above 25,000ft.

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## pbehn (Jul 4, 2021)

P-39 Expert said:


> Hmmm. "Neither type (MkII Spitfires and Hurricanes) promised to be a satisfactory aircraft at over 25000'." And "the 109E with a 550lb bomb had a ceiling of 25000' at most." "Generally only squadrons that were already airborne had a chance to close with the enemy (at 30000')." "The function of these squadrons was not to intercept as soon as possible but to cover those squadrons from London who were still gaining height." *Sounds to me like the British fighters had a very hard time over 25000' and the bomb carrying 109Es could not get over 25000'*. Lots of talk about ordering the British fighters to 30000' but also very hard for them to get there. This was all only during the last month of the BoB (October).
> 
> I will give you that the 109E apparently could cruise at 30000' but both British fighters had a very difficult time getting over 25000'.
> 
> ...


Do you realise you are nit picking and pettifogging with Dowding and Park, who I am sure would have loved your expertise but are sadly no longer with us. Regarding the bold part, you should add "in the time provided". As a man who loves his charts you can look at a chart of a Spitfire Mk I and Mk II and find the rate of climb above 15,000ft and 20,000ft and 25,000ft. When the rate of climb is 100ft min it takes 10 minutes to climb 1,000 ft, at 180MPH a plane has done 30miles in 10 minutes, it is 70 miles from Dover to the outskirts of London.

A Hurricane MkI could get to 30,000ft but it took 18 minutes and at 30,000ft its RoC was 570ft min. No where near good enough to stop these attacks. Hurricane Mk I Performance

Edit to take account of MikeMeech's post A squadron of Spitfires took 27 minutes to get to 30,000 ft, it doesnt take a Bf109 27 minutes to fly from Calais to London.

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## GregP (Jul 4, 2021)

I am at a complete loss as to why we are even talking about the ceiling of a fighter carrying a bomb. The whole intent of carrying a bomb is to drop it on something you want to damage. All else is unimportant unless the bomb-carrying fighter gets attacked by another fighter. Then, he drops the bomb and fights ... or he dies.

Fighter versus fighter combat didn't involve bomb-carrying airplanes. If the fighters were NOT carrying bombs, then even a Spitfire Mk IA had a service ceiling of 34,400 feet (10,485 m) and really didn't have any trouble getting to over 30,000 feet, regardless of P-39 Expert's claims. The Spitfire Mk I went into service in Aug 1938, so it was around when the war broke out. The Mk II went into service in Sep 1941.

So, the Spitfires COULD and DID get over 30,000 feet.

Carrying a bomb or not for the Bf 109 was irrelevant.

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## Snautzer01 (Jul 4, 2021)

GregP said:


> we're just sick of the P-39.


No i am not so, there is no "we" I do understand someone is a bit pig headed but it does draw as i said before people to the books. I do like the p-39 and it did do good service for all reasons discussed and it is not even remotely in the same league as Spitfires FW190 or at most airframes at the time. That said, i did learn a lot from it. Why and why not.
So please could you not use the "We" in this? Thanks.

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## Snautzer01 (Jul 4, 2021)

GregP said:


> The whole intent of carrying a bomb is to drop it on something you want to damage


It also is a good cheap way to keep the other guy not letting his assets being used for other things than defence. Even almost dead battle ships need a great deal of attention. Ask the RAF.

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## pbehn (Jul 4, 2021)

Snautzer01 said:


> It also is a good cheap way to keep the other guy not letting his assets being used for other things than defence. Even almost dead battle ships need a great deal of attention. Ask the RAF.


These Jabo raids stopped when the RAF started leaning into France, so instead of the LW losing pilots over UK the RAF started losing them over France.


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## Snautzer01 (Jul 4, 2021)

pbehn said:


> These Jabo raids stopped when the RAF started leaning into France, so instead of the LW losing pilots over UK the RAF started losing them over France.


Nuisance raids did continue i think well into 1944. And what is your time frame? RAF started leaning into France during and after BoB. Got shot down a lot but leaning anyway. Not countering these raids. They did shoot planes down but it also did keep a force down on Britain. And that is the point i make.


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## MikeMeech (Jul 4, 2021)

pbehn said:


> Do you realise you are nit picking and pettifogging with Dowding and Park, who I am sure would have loved your expertise but are sadly no longer with us. Regarding the bold part, you should add "in the time provided". As a man who loves his charts you can look at a chart of a Spitfire Mk I and Mk II and find the rate of climb above 15,000ft and 20,000ft and 25,000ft. When the rate of climb is 100ft min it takes 10 minutes to climb 1,000 ft, at 180MPH a plane has done 30miles in 10 minutes, it is 70 miles from Dover to the outskirts of London.
> 
> A Hurricane MkI could get to 30,000ft but it took 18 minutes and at 30,000ft its RoC was 570ft min. No where near good enough to stop these attacks. Hurricane Mk I Performance


Hi

For information, Park did concern himself on climb rates for squadrons, in Instruction No. 28 he has details of a single squadron plus the extra time taken by two or three squadrons in wings. He stresses the importance of getting a single squadron up to intercept and for the controllers not to wait to get the whole formation up to height.










Mike

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## pbehn (Jul 4, 2021)

MikeMeech said:


> Hi
> 
> For information, Park did concern himself on climb rates for squadrons, in Instruction No. 28 he has details of a single squadron plus the extra time taken by two or three squadrons in wings. He stresses the importance of getting a single squadron up to intercept and for the controllers not to wait to get the whole formation up to height.
> View attachment 631112
> ...


Excellent post, showing clearly how much research Park put into the issue. Its the first time I have seen the different rates of climb for individual planes, squadrons and pairs of squadrons and groups quantified. In fact he wasnt interested in the performance of an individual aeroplane, he knew about a Hurricane MkI because he had one as his own transport, he was interested in the "average performance of a good squadron".


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## pbehn (Jul 4, 2021)

Snautzer01 said:


> Nuisance raids did continue i think well into 1944. And what is your time frame? RAF started leaning into France during and after BoB. Got shot down a lot but leaning anyway. Not countering these raids. They did shoot planes down but it also did keep a force down on Britain. And that is the point i make.


By "These Jabo raids" I just meant the Bf109 high altitude raids in 1940. I was actually agreeing with your point about occupying assets.

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## Thumpalumpacus (Jul 4, 2021)

If one doesn't want to read the writing on the brick wall, don't open this thread; I think by now everyone knows what this involves -- a lot of cherry-picking stubbornness, accompanied by a wealth of information about why that might be wrong.

I open this thread because I am learning an awful lot of stuff. So long as I put 

 P-39 Expert
's comments into the context of his bias, I can learn something from even them. I hope he keeps working this thread so that I can learn stuff.

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## 33k in the air (Jul 4, 2021)

P-39 Expert said:


> Why would the British even worry about 109Es at those heights? The 109E bombers couldn't hit anything with any accuracy from that altitude so they were doing minimal if any damage.



For the same reason the Germans worried about British bombers in 1941.


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## pbehn (Jul 4, 2021)

Thumpalumpacus said:


> If one doesn't want to read the writing on the brick wall, don't open this thread; I think by now everyone knows what this involves -- a lot of cherry-picking stubbornness, accompanied by a wealth of information about why that might be wrong.
> 
> I open this thread because I am learning an awful lot of stuff. So long as I put
> 
> ...


This has been going on for years not months and not just in this thread, nothing new gets posted by our expert but he is prepared to dismiss anyone and everyone who doesnt agree with his opinion, he hasnt reached Churchill yet but is just a few steps below at Dowding and Park, most it is driven by a dislike of the British who he holds responsible for the P-39 not being seen as the best fighter of WW2.

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## GrauGeist (Jul 4, 2021)

P-39 Expert said:


> Why do you care? Why do you feel compelled to reply to my every post? ALL this has been posted on here lots of times, hence the groundhog theme.


Because you post bullshit and this site is about the exchange/discussion of historical points, not War Thunder fantasy trippin'.

That's why.

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## Thumpalumpacus (Jul 4, 2021)

pbehn said:


> This has been going on for years not months and not just in this thread, nothing new gets posted by our expert but he is prepared to dismiss anyone and everyone who doesnt agree with his opinion, he hasnt reached Churchill yet but is just a few steps below at Dowding and Park, most it is driven by a dislike of the British who he holds responsible for the P-39 not being seen as the best fighter of WW2.



I gathered that much. I did see that the staff recently asked him to focus his P-39 discussion into this thread, and I think that's fair, unless the Airacobra is a legitimate factor in another discussion, and he doesn't start rehashing his biases there as well as here.

That way, people know to don their hip-waders before opening this thread, and don't get taken by surprise in so many other useful ones.


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## pbehn (Jul 4, 2021)

Thumpalumpacus said:


> I gathered that much. I did see that the staff recently asked him to focus his P-39 discussion into this thread, and I think that's fair, unless the Airacobra is a legitimate factor in another discussion, and he doesn't start rehashing his biases there as well as here.
> 
> That way, people know to don their hip-waders before opening this thread, and don't get taken by surprise in so many other useful ones.


For those new to the forum it is hard to explain how much my back hurt putting those fuel tanks in then taking them out, taking the wing guns out and putting them in again. The worst part was fitting the extra external fuel tank and the bomb in the same place, it gave the range and firepower needed for a fighter bomber but was actually a complete impossibility. Our expert is much more of an expert now than he was when he first started posting, because he has been educated by people who actually know more than he does about the P-39 and I am not one of them.

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## wuzak (Jul 4, 2021)

GregP said:


> Fighter versus fighter combat didn't involve bomb-carrying airplanes. If the fighters were NOT carrying bombs, then even a Spitfire Mk IA had a service ceiling of 34,400 feet (10,485 m) and really didn't have any trouble getting to over 30,000 feet, regardless of P-39 Expert's claims. The Spitfire Mk I went into service in Aug 1938, so it was around when the war broke out. The Mk II went into service in Sep 1941.



The MK II was being deployed in 1940, certainly by September 1940. The Mk V was arriving in early 1941.




GregP said:


> So, the Spitfires COULD and DID get over 30,000 feet.



A Spitfire I with Merlin II and fixed pitch propeller using 87 octane fuel could get over 30,000ft in late 1938/early 1939.

Absolute ceiling estimated to be 32,800ft, height reached on test 32,400ft.






Spitfire Mk I K.9787 Trials Report


Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.



www.spitfireperformance.com






With a 2 pitch airscrew the absolute ceiling went up to 35,500ft. Greatest height reached on test, 32,700ft.





__





Spitfire Mk I K.9793 Trials Report


Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.



www.spitfireperformance.com






With 2 pitch airscrew and two 20mm cannon fitted a Spitfire I had an estimated service ceiling of 34,500ft 






Spitfire Mk I L.1007 Trials Report


Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.



www.spitfireperformance.com





Those last 2 were in July 1939.

Spitfire I with constant speed prop had roughly the same ceiling, but improved the rate of climb at 30,000ft from 470ft/min (Merlin III, 2 pitch prop) and 325 ft/min (Merlin II, fixed pitch prop) to 660ft/min.






Spitfire Mk I N.3171 Trials Report


Spitfire Performance Testing, wartime flight trials and reports of Spitfire aircraft. Spitfire Mk I data.



www.spitfireperformance.com

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## pbehn (Jul 4, 2021)

wuzak said:


> The MK II was being deployed in 1940, certainly by September 1940. The Mk V was arriving in early 1941.


AFAK the new factory at Castle Bromwich only produced MkIIs so its production marks the start of its introduction into the RAF starting as you say around August September 1940 depending on what is regarded as in service or in combat etc. Into the RAF doesnt mean it was delivered to Manston, generally squadrons away from the front line equipped with a new type and then were moved to the front line as a unit.


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## fubar57 (Jul 4, 2021)



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## pbehn (Jul 4, 2021)

fubar57 said:


> View attachment 631120​


I think he is nearly there, just need to discredit or dismiss FDR and Ike and the job is done.


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## Thumpalumpacus (Jul 4, 2021)

pbehn said:


> For those new to the forum it is hard to explain how much my back hurt putting those fuel tanks in then taking them out, taking the wing guns out and putting them in again. The worst part was fitting the extra external fuel tank and the bomb in the same place, it gave the range and firepower needed for a fighter bomber but was actually a complete impossibility. Our expert is much more of an expert now than he was when he first started posting, because he has been educated by people who actually know more than he does about the P-39 and I am not one of them.



That's not even mentioning the armor!

I know little about the airplane itself, so I appreciate the back-and-forth.


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## Thumpalumpacus (Jul 4, 2021)

pbehn said:


> I think he is nearly there, just need to discredit or dismiss FDR and Ike and the job is done.



I can't tell you how many times I've argued FDR was a craptastic president, or how I know that.

Mainly because I don't think I've ever argued that, and I don't have the experience to make that judgement.


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## Andrew Arthy (Jul 4, 2021)

P-39 Expert said:


> Hmmm. "Neither type (MkII Spitfires and Hurricanes) promised to be a satisfactory aircraft at over 25000'." And "the 109E with a 550lb bomb had a ceiling of 25000' at most." "Generally only squadrons that were already airborne had a chance to close with the enemy (at 30000')." "The function of these squadrons was not to intercept as soon as possible but to cover those squadrons from London who were still gaining height." Sounds to me like the British fighters had a very hard time over 25000' and the bomb carrying 109Es could not get over 25000'. Lots of talk about ordering the British fighters to 30000' but also very hard for them to get there. This was all only during the last month of the BoB (October).
> 
> I will give you that the 109E apparently could cruise at 30000' but both British fighters had a very difficult time getting over 25000'.
> 
> ...


Hi,

From a November 1940 report on three captured Bf 109 fighter-bomber pilots, based on interrogations and secret recordings of their conversations, describing their bombing missions over England:

"_The normal operational procedure of this Staffel is to fly at about 26,000 feet, and dive at a previously arranged angle between 40 and 60 degrees. They pull out at 16,000 feet. ... The escort flew at either side and to the rear of the bombers, two Staffeln flying at between 1,800 and 2,500 feet above, and two Staffeln between 600 and 1,000 feet below._" Source: NA AIR 40/3127, A.I.1.(k) Report no. 912/1940

Bf 109 fighter-bomber pilot Viktor Kraft, from a different unit and shot down on 11 December 1940, mentioned: "_our normal height of 7,000-8,000 metres_". Source: Goss, _Luftwaffe Fighter-Bombers Over Britain_, p.54

Cheers,
Andrew A.
Air War Publications - www.airwarpublications.com

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## GregP (Jul 5, 2021)

OK, I won't use the word "we." I'm sick of the P-39 and am out of here.

There hasn't been much new information that wasn't well-known by WWII aviation fans, but there HAS been a lot of fantasy claims that are ludicrous. Enough for me. You folks who haven't had enough of P-39s, please enjoy. Really.

I have no dog in this hunt and will never claim the P-39 to be anything but an interim solution to a poorly-recognized problem. I love to see one flying today, but that won't make it a good WWII fighter, just a WWII survivor that happens to be flyable. That alone makes it worth it to me to watch one fly without giving it much combat credit to it that it doesn't deserve.

Cheers to everyone.

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## P-39 Expert (Jul 5, 2021)

MikeMeech said:


> Hi
> 
> For information, Park did concern himself on climb rates for squadrons, in Instruction No. 28 he has details of a single squadron plus the extra time taken by two or three squadrons in wings. He stresses the importance of getting a single squadron up to intercept and for the controllers not to wait to get the whole formation up to height.
> View attachment 631112
> ...


17-20 minutes after radar detection for a 109E to bomb, and it takes a Spitfire squadron 27 minutes to get to 30000'? Why bother. Even patrolling at 20000' the Spitfire has only about 30-40min patrol time, 15-20min after the second climb from 20000' to 30000'. The 109E will have already bombed or is just about to bomb by the time the Spitfires get up to 30000'. Not that the 109s could hit anything from that altitude anyway. Bombers with bombardiers and bombsights still weren't very accurate from 20000'. 

The whole purpose of these 109E bomber raids was to draw the British into battle. As smart as the British were I doubt they took that bait very often. Their purpose was to destroy enemy bomber formations, not wasting valuable time and resources getting to 30000' to discourage some fighter-bombers who couldn't hit anything from high altitude anyway.


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## pbehn (Jul 5, 2021)

P-39 Expert said:


> 17-20 minutes after radar detection for a 109E to bomb, and it takes a Spitfire squadron 27 minutes to get to 30000'? *Why bother. * Even patrolling at 20000' the Spitfire has only about 30-40min patrol time, 15-20min after the second climb from 20000' to 30000'. The 109E will have already bombed or is just about to bomb by the time the Spitfires get up to 30000'. Not that the 109s could hit anything from that altitude anyway. Bombers with bombardiers and bombsights still weren't very accurate from 20000'.
> 
> The whole purpose of these 109E bomber raids was to draw the British into battle. As smart as the British were I doubt they took that bait very often. Their purpose was to destroy enemy bomber formations, not wasting valuable time and resources getting to 30000' to discourage some fighter-bombers who couldn't hit anything from high altitude anyway.


Is that a joke? What was fighter command for? You are not the person to decide what the RAF was for or how it should do its job, especially since your agenda is always something to do with the P-39. A few days ago you denied these raids did or could take place now you are the expert.

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## Juha3 (Jul 5, 2021)

P-39 Expert said:


> 17-20 minutes after radar detection for a 109E to bomb, and it takes a Spitfire squadron 27 minutes to get to 30000'? Why bother. Even patrolling at 20000' the Spitfire has only about 30-40min patrol time, 15-20min after the second climb from 20000' to 30000'. The 109E will have already bombed or is just about to bomb by the time the Spitfires get up to 30000'. Not that the 109s could hit anything from that altitude anyway. Bombers with bombardiers and bombsights still weren't very accurate from 20000'.
> 
> The whole purpose of these 109E bomber raids was to draw the British into battle. As smart as the British were I doubt they took that bait very often. Their purpose was to destroy enemy bomber formations, not wasting valuable time and resources getting to 30000' to discourage some fighter-bombers who couldn't hit anything from high altitude anyway.


Because of the gravity, bombs dropped always hit something, maybe a fuel storage tank or an empty field, whatever. But sometimes they explode amongst densely packed people. A couple examples, at first British ignored high flying (around 40,000 ft) Ju 86Rs, but on 28 August 1942 one of them dropped a bomb which hit in the centre of the Bristol killing 48 people and seriously wounding 26 and slightly injuring 30. Here in Helsinki in 1942 a single bomb dropped from high flying Pe-2 killed 42, mostly children. You might not know this but one of the main duties of air forces was and still is to protect the citizens of the country.

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## pbehn (Jul 5, 2021)

Juha3 said:


> Because of the gravity, bombs dropped always hit something, maybe a fuel storage tank or an empty field, whatever. But sometimes they explode amongst densely packed people. A couple examples, at first British ignored high flying (around 40,000 ft) Ju 86Rs, but on 28 August 1942 one of them dropped a bomb which hit in the centre of the Bristol killing 48 people and seriously wounding 26 and slightly injuring 30. Here in Helsinki in 1942 a single bomb dropped from high flying Pe-2 killed 42, mostly children. You might not know this but one of the main duties of air forces was and still is to protect the citizens of the country.


Ah, but if you dont bother about such attacks then the P-39 would be perfect for British use, so they had no reason to get out of the contract. Imagine if such an event took place in London and Dowding told Churchill "we cant be bothered, too much effort required".

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## FLYBOYJ (Jul 5, 2021)

P-39 Expert said:


> 17-20 minutes after radar detection for a 109E to bomb, and it takes a Spitfire squadron 27 minutes to get to 30000'? Why bother. Even patrolling at 20000' the Spitfire has only about 30-40min patrol time, 15-20min after the second climb from 20000' to 30000'. The 109E will have already bombed or is just about to bomb by the time the Spitfires get up to 30000'. Not that the 109s could hit anything from that altitude anyway. Bombers with bombardiers and bombsights still weren't very accurate from 20000'.
> 
> The whole purpose of these 109E bomber raids was to draw the British into battle. As smart as the British were I doubt they took that bait very often. * Their purpose was to destroy enemy bomber formations, not wasting valuable time and resources getting to 30000' to discourage some fighter-bombers who couldn't hit anything from high altitude anyway.*


So I guess those dispatches from Parks and Mallory were exaggerated? But wait, if I recall both Parks and Mallory were "just pilots" (Or at least they began their careers that way)

Even if one bomb landed on a laundromat in the middle of London, woke up a few hundred people, dispatched fireman and alerted air defenses, an objective was achieved. But wait, you read differently while sitting in your lounge chair

I would give this a rest. I'm trying not to get into this too much and have given up trying to educate you on things that I have actually done, (hell, you ignore our resident F-15 pilot) but you're really making a fool out of yourself.

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## pbehn (Jul 5, 2021)

A standard load for a Do17 was 4 x 250Kg bombs, for a He 111 it was 8 x 250Kg bombs. These are bombers. 8 Bf 109s carrying 8 x 250Kg bombs are not bombers and should be ignored?

Does anyone know how many fairies can dance on the head of a pin?

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## Shortround6 (Jul 5, 2021)

pbehn said:


> Does anyone know how many fairies can dance on the head of a pin?


1/2 the number of angels?

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## pbehn (Jul 5, 2021)

Shortround6 said:


> 1/2 the number of angels?


What do 3.5 fairies look like?


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## nuuumannn (Jul 5, 2021)

These threads always end up the same. Pointless circular arguments... Tiresome.

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## Airframes (Jul 5, 2021)

*But !*
Now that we have all of the information from our resident "expert", it would seem that, if the Luftwaffe had been equipped with the P-39, and nothing else, they would have achieved total victory during the BoB, and eventually won the war .............

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## buffnut453 (Jul 5, 2021)

P-39 Expert said:


> 17-20 minutes after radar detection for a 109E to bomb, and it takes a Spitfire squadron 27 minutes to get to 30000'? Why bother. Even patrolling at 20000' the Spitfire has only about 30-40min patrol time, 15-20min after the second climb from 20000' to 30000'. The 109E will have already bombed or is just about to bomb by the time the Spitfires get up to 30000'. Not that the 109s could hit anything from that altitude anyway. Bombers with bombardiers and bombsights still weren't very accurate from 20000'.
> 
> The whole purpose of these 109E bomber raids was to draw the British into battle. As smart as the British were I doubt they took that bait very often. Their purpose was to destroy enemy bomber formations, not wasting valuable time and resources getting to 30000' to discourage some fighter-bombers who couldn't hit anything from high altitude anyway.



Congratulations! I hereby dub thee the honorific title of Bert Huggins, King Amongst Trolls (you could also have Tom or William Huggins if you prefer).

Every one of these points has been made before and every single one of them is countered by information that you choose to ignore. You refuse to engage with any of the reasoned posts that others make, and are entirely dismissive of contemporary records (except those that suit your argument).

I keep hoping that the sun will come up and turn Bert Huggins to stone so at least we can get on with discussions that collaborate to build knowledge....alas, we remain in utter darkness.

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## 33k in the air (Jul 5, 2021)

pbehn said:


> Does anyone know how many fairies can dance on the head of a pin?



Wouldn't that be the number of P-39s that can outperform the head of a pin?

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## Shortround6 (Jul 5, 2021)

nuuumannn said:


> These threads always end up the same. Pointless circular arguments... Tiresome.




Sometimes it leads to extra digging. 

I _think_ I know were part of the P-39/P-400 weight escalation came from. Just a theory. 

The P-39C was rated at 7.5 positive Gs load factor and 3.75 negative and this was at 6662lbs (gross weight performance figures were calculated at) While the *standard* service load factor for US pursuit planes was supposed to be plus 8 and negative 4 (with plus 12 and negative 6(?) being the ultimate load factor). 
The P-39C needed self sealing tanks at the least plus a few other desired upgrades. 
At 7100lbs (full fuel and oil tanks and few minor items of equipment) a P-39C airframe would have been good for a ball park stress load of 7.04. 
Perhaps this was too low for the USAAC?
Move the .30 cal guns to the wings (and add two more) is really going to push things over the top. 

I have no idea how much structural bracing was needed to get the P-39D/P-400 up to the desired 8 G service load factor but I believe the change was made. 

A chart provided by Neal Stirling ; Structure weight data and drag analysis.

Lists the Aircobra as having an ultimate load factor of 12 at 7400lbs. Ultimate load of 12 was the result of multiplying the service load of 8 by a safety factor of 1.5.

Bell had tried to build a light weight fighter but even before the P-39C the weight had escalated beyond the original calculations. 
This was certainly not unheard of. 
The sales Brochure for the Curtiss Hawk 75 list two different load factors for the Cyclone powered and Twin Wasp powered versions with the heavier Twin Wasp powered model having the lower load factor. Brochure states the Twin Wasp powered model could be provided at the standard 12 G ultimate load factor at additional cost and _weight._

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## Thumpalumpacus (Jul 5, 2021)

buffnut453 said:


> Congratulations! I hereby dub thee the honorific title of Bert Huggins, King Amongst Trolls (you could also have Tom or William Huggins if you prefer).
> 
> Every one of these points has been made before and every single one of them is countered by information that you choose to ignore. You refuse to engage with any of the reasoned posts that others make, and are entirely dismissive of contemporary records (except those that suit your argument).
> 
> I keep hoping that the sun will come up and turn Bert Huggins to stone so at least we can get on with reasoned discussions....alas, we remain in utter darkness.



What the hell's a burrahobbit?!

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## nuuumannn (Jul 5, 2021)

Shortround6 said:


> Sometimes it leads to extra digging.



Oh, completely, the information that comes out is useful and appreciated, but it's the descent into pointless bickering and the constant going round in circles that is a trend of these threads.

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## pbehn (Jul 6, 2021)

P-39 Expert said:


> The whole purpose of these 109E bomber raids was to draw the British into battle. As smart as the British were I doubt they took that bait very often.


In your extensive reading of US military history, which USA military service do you most doubt would defend the USA border or capital from attack when ordered to do so? 

During October the RAF lost 53 pilots and claimed 212 destroyed. 115 probables 140 damaged The claims are obviously much higher than actual but it does seem that a lot "took the bait" quite often, so no more of your doubts eh?








October 1940 – Battle of Britain Day by Day







battleofbritain.wordpress.com

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## Milosh (Jul 6, 2021)

pbehn said:


> In your extensive reading of US military history, which USA military service do you most doubt would defend the USA border or capital from attack when ordered to do so?
> 
> During October the RAF lost 53 pilots and claimed 212 destroyed. 115 probables 140 damaged The claims are obviously much higher than actual but it does seem that a lot "took the bait" quite often, so no more of your doubts eh?
> 
> ...


I doubt very much that Expert actually read any BoB histories.

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## pbehn (Jul 6, 2021)

Milosh said:


> I doubt very much that Expert actually read any BoB histories.


Only a short time ago he was denying any high level raids took place or could take place, the very discussion made him cringe. His assertion that the only reason for the raids was to draw the RAF into battle is also the British into battle is also completely incorrect. If you read the link for October the LW were experimenting with many different methods and targets. Some individual Bf110 went at high level to the Midlands, two Do17s were shot down with RAF markings or trying to impersonate Blenheims (as it says). They used massed raids, small groups and streams. The objective was clearly to drop bombs, one individual bomb killed 13 people while two others hit hospitals so I take exception to the idea that stopping them was a "take the bait" option.


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## P-39 Expert (Jul 6, 2021)

pbehn said:


> Only a short time ago he was denying any high level raids took place or could take place, the very discussion made him cringe. His assertion that the only reason for the raids was to draw the RAF into battle is also the British into battle is also completely incorrect. If you read the link for October the LW were experimenting with many different methods and targets. Some individual Bf110 went at high level to the Midlands, two Do17s were shot down with RAF markings or trying to impersonate Blenheims (as it says). They used massed raids, small groups and streams. The objective was clearly to drop bombs, one individual bomb killed 13 people while two others hit hospitals so I take exception to the idea that stopping them was a "take the bait" option.


Keep this up. I still doubt much combat was at 30000'. Even if the 109E escort was at 30000' the first maneuver made would mean loss of altitude. At 30000' those BoB planes were just barely hanging on up there. And no bomb equipped 109E was near 30000'. 

And why do you keep bringing up the P-39 when the first production was not until spring of 1941? Keep trolling, I'll always take the bait.

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## FLYBOYJ (Jul 6, 2021)

P-39 Expert said:


> Keep this up. I still doubt much combat was at 30000'. Even if the 109E escort was at 30000' the first maneuver made would mean loss of altitude. At 30000' those BoB planes were just barely hanging on up there. And no bomb equipped 109E was near 30000'.
> 
> And why do you keep bringing up the P-39 when the first production was not until spring of 1941? Keep trolling, I'll always take the bait.


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## Snautzer01 (Jul 6, 2021)

FLYBOYJ said:


> View attachment 631354

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## pbehn (Jul 6, 2021)

P-39 Expert said:


> Keep this up. I still doubt much combat was at 30000'. Even if the 109E escort was at 30000' the first maneuver made would mean loss of altitude. At 30000' those BoB planes were just barely hanging on up there. And no bomb equipped 109E was near 30000'.
> 
> And why do you keep bringing up the P-39 when the first production was not until spring of 1941? Keep trolling, I'll always take the bait.


Why do you bring up anything, it is irrelevant what you think or doubt or even what you state as a fact because your facts are just your opinions. Actual facts you dismiss as "joe pilot's word". The discussion started when you claimed there was no difference in principle between operations on the east front and in Europe, which would mean a plane that was a success in the east could have been a success in the west if only those pesky British hadnt refused to pay. Which US service do you doubt would defend the USA when ordered? Do you only feel the need to air these doubts about the RAF?

You troll the forum, turning every thread into a P-39 thread and always with the same agenda, the valiant P-39 was screwed over by perfidious Albion. You have stated that the P-39N had adequate performance up to 30,000ft when it clearly doesnt. It wouldnt have had adequate performance on 1940 let alone 1941 and later when the Fw190 was introduced, as for your continual complaint that the British increased the weight of the P-39 you have just been put right on that one.

How long does it take a squadron of P-39s to get to 30,000 ft, you must know because you claim to know more than Park, how long for 2 squadrons together?

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## SaparotRob (Jul 6, 2021)

I gave you a like for "Perfidious Albion". Some 30 odd years ago a friend came up with a super villain named that.
Albion, the Perfidious.


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## pbehn (Jul 6, 2021)

SaparotRob said:


> I gave you a like for "Perfidious Albion". Some 30 odd years ago a friend came up with a super villain named that.
> Albion, the Perfidious.


Traditional name for the English in France 









Perfidious Albion - Wikipedia







en.wikipedia.org





The use of the adjective "perfidious" to describe England has a long history; instances have been found as far back as the 13th century.[1]​ A very similar phrase was used in a sermon by 17th-century French bishop and theologian Jacques-Bénigne Bossuet:[2]​


​_'L'Angleterre, ah, la perfide Angleterre,
que le rempart de ses mers rendoit inaccessible aux Romains,
la foi du Sauveur y est abordée._
England, oh perfidious England,
Shielded against the Romans by her ocean ramparts,
Now receives the true faith.
The coinage of the phrase in its current form, however, is conventionally attributed to Augustin Louis de Ximénès, a French-Spanish playwright who wrote it in a poem entitled _L'Ère des Français_, published in 1793


​_Attaquons dans ses eaux la perfide Albion._
Let us attack perfidious Albion in her waters.

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## SaparotRob (Jul 6, 2021)

Oh, I know about that. My friend took gleeful joy in explaining it. Repeatedly.

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## pbehn (Jul 6, 2021)

SaparotRob said:


> Oh, I know about that. My friend took gleeful joy in explaining it. Repeatedly.


When I worked in France we used to joke about it avec les grenouilles.

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## Peter Gunn (Jul 6, 2021)

SaparotRob said:


> There's an Edsel Expert?


I thought you were...


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## SaparotRob (Jul 6, 2021)

Well the 1959 Edsel Corsair was a distinct improvement over the 1958 Edsel Corsair. You'll notice that the grill of the 1959 is of a lighter, cleaner design. By removing the nose armour, the Edsel Corsair had become competitive with the Chevrolet Corvette and the Ford Thunderbird.

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## buffnut453 (Jul 6, 2021)

P-39 Expert said:


> Keep this up. I still doubt much combat was at 30000'. Even if the 109E escort was at 30000' the first maneuver made would mean loss of altitude. At 30000' those BoB planes were just barely hanging on up there. And no bomb equipped 109E was near 30000'.



How about you stop keeping this up and provide evidence for these statements for once? 

You previously accepted that the Me109 could.cruise at 30,000ft but now you're saying that any manoeuvre would result in loss of altitude. Cruising isn't usually in a straight line so which is correct?

How about actually engaging in a.conversation rather than simply restating your incorrect opinions?


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## Peter Gunn (Jul 6, 2021)

Thumpalumpacus said:


> Yabut with how much tea aboard? The world wonders.


Sadly, a fact lost to history.

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## Peter Gunn (Jul 6, 2021)

SaparotRob said:


> Well the 1959 Edsel Corsair was a distinct improvement over the 1958 Edsel Corsair. You'll notice that the grill of the 1959 is of a lighter, cleaner design. By removing the nose armour, the Edsel Corsair had become competitive with the Chevrolet Corvette and the Ford Thunderbird.


But the weight of the tailfins would have a negative effect on the C.o.G.... You'd get tailpipes dragging on the ground even at low throttle, let alone when you have the accelerator to the floor.

Steering wouldn't be too hot either, the front wheels are going to have minimal contact with the pavement, *what kind of tomfoolery are you trying to sell here?*

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## SaparotRob (Jul 6, 2021)

It's already been posted here that rearward c.o.g. doesn't affect performance.

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## XBe02Drvr (Jul 6, 2021)

SaparotRob said:


> It's already been posted here that rearward c.o.g. doesn't affect performance.


Along with numerous other patently false assertions. Tailpipe dragging definitely CAN prevent attaining escape velocity!
"Son, do you realize how fast you were going BEFORE you tried to get away from me? And with the mayor's daughter onboard, despite the protection order against you? You're in deep do-do, boy!"

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## GregP (Jul 6, 2021)

Hey, I think I KNOW that cop you're talking about above ...

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## SaparotRob (Jul 6, 2021)

I really got to hand it to a couple of our posters. I try to come up with patently ridiculous claims for an absurd position and I run out of steam. I don't know how they do it.

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## XBe02Drvr (Jul 6, 2021)

GregP said:


> Hey, I think I KNOW that cop you're talking about above ...


Never mind him. Tell us about the mayor's daughter!

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## XBe02Drvr (Jul 6, 2021)

SaparotRob said:


> I really got to hand it to a couple of our posters. I try to come up with patently ridiculous claims for an absurd position and I run out of steam. I don't know how they do it.


I heard it was all about stretching exercises to improve cheek elasticity. The more tongue you can get in, the better. Chipmunk DNA helps, too, they say.

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## Clayton Magnet (Jul 6, 2021)

P-39 Expert said:


> And why do you keep bringing up the P-39

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## Glider (Jul 6, 2021)

P-39 Expert said:


> And why do you keep bringing up the P-39 when the first production was not until spring of 1941? Keep trolling, I'll always take the bait.


Why do *WE* keep bringing up the P39!!

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## Airframes (Jul 6, 2021)

Probably something in last night's curry - nutsacks maybe ?


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## GrauGeist (Jul 6, 2021)

P-39 Expert said:


> And why do you keep bringing up the P-39 when the first production was not until spring of 1941?


We can discuss the P-39 in general discussion without becoming overly obsessed with it.

Also, I hate to point out the obvious, but the Luftwaffe continued to attack England after October 1940.
The last major bombing offensive was Operation Steinbock between January and May 1944.
The last bombing of England was on 17 March 1945.


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## SaparotRob (Jul 6, 2021)

I think he pranked us!


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## 33k in the air (Jul 6, 2021)

Thumpalumpacus said:


> The world wonders.



I remember that time when the world wondered where Task Force 34 was.

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## special ed (Jul 6, 2021)

Maybe the institution only allows computer access at certain times.

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## P-39 Expert (Jul 6, 2021)

Shortround6 said:


> Sometimes it leads to extra digging.
> 
> I _think_ I know were part of the P-39/P-400 weight escalation came from. Just a theory.
> 
> ...


Are you saying the additional weight came from structural strengthening sometime after production of the C model in time for the D model and P-400? According to your P-39C manual empty weight was 5016lbs. The P-400 weighed 5550lbs empty. That's a difference of 534lbs. 240lbs was the self sealing fuel tanks. The book "Cobra" shows "minor empty and useful load changes" in Jan '41 and "engine and fixed equipment weight increase" in June '41 with production beginning in July, but those changes only account for 165lbs. I don't know where the additional 129lbs came from. Maybe it WAS structural bracing.


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## pbehn (Jul 6, 2021)

P-39 Expert said:


> Are you saying the additional weight came from structural strengthening sometime after production of the C model in time for the D model and P-400? According to your P-39C manual empty weight was 5016lbs. The P-400 weighed 5550lbs empty. That's a difference of 534lbs. 240lbs was the self sealing fuel tanks. The book "Cobra" shows "minor empty and useful load changes" in Jan '41 and "engine and fixed equipment weight increase" in June '41 with production beginning in July, but those changes only account for 165lbs. I don't know where the additional 129lbs came from. Maybe it WAS structural bracing.


What were the 25 airframe modifications that grounded all P-39s delivered to UK and meant only 4 were ever in operational service?


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## P-39 Expert (Jul 6, 2021)

Double post


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## pbehn (Jul 6, 2021)

P-39 Expert said:


> Double post


Well thats closer than you normally get to an answer. Normally if you make a double post, you have to edit it to say "double post".


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## P-39 Expert (Jul 6, 2021)

FLYBOYJ said:


> So I guess those dispatches from Parks and Mallory were exaggerated? But wait, if I recall both Parks and Mallory were "just pilots" (Or at least they began their careers that way)
> 
> Even if one bomb landed on a laundromat in the middle of London, woke up a few hundred people, dispatched fireman and alerted air defenses, an objective was achieved. But wait, you read differently while sitting in your lounge chair
> 
> I would give this a rest. I'm trying not to get into this too much and have given up trying to educate you on things that I have actually done, (hell, you ignore our resident F-15 pilot) but you're really making a fool out of yourself.


Please give up on trying to educate me. I already have way more education than I can ever use. Thank you.

Your reply was to my post quoting Keith Park from post #2189. Do you honestly feel that a single seat fighter could bomb with any accuracy from those heights? Could they hit (or even come close to) a specific target?

And what is likely to happen to those Spitfires climbing from 20000' up to even 25000' where the fighter bombers were, not to mention the reported 30000' where their escort was? In the four minutes that they have to intercept don't you think that those planes or the escort above will see the Spitfires crawling up at less than 500fpm (vertical speed about 5.5mph, a little faster than walking). Aren't the escorts going to bounce the Spitfires from above? Seems like the ideal situation for the escorts, or even the FBs. 

That seems crazy to me and I don't think the British were crazy. Not much interception going on there in my opinion. They weren't about to waste finite resources chasing fighter bombers at altitudes where any bombing accuracy at all was pure luck. Not then there are bomber formations at 20000' and under.


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## FLYBOYJ (Jul 6, 2021)

P-39 Expert said:


> Please give up on trying to educate me. I already have way more education than I can ever use.


Yea - it shows


P-39 Expert said:


> Your reply was to my post quoting Keith Park from post #2189. Do you honestly feel that a single seat fighter could bomb with any accuracy from those heights? Could they hit (or even come close to) a specific target?


I'll repeat because you're sooooo educated the brain cells might have had a hic-up...

*"Even if one bomb landed on a laundromat in the middle of London, woke up a few hundred people, dispatched fireman and alerted air defenses, an objective was achieved."*


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## pbehn (Jul 6, 2021)

P-39 Expert said:


> Your reply was to my post quoting Keith Park from post #2189. Do you honestly feel that a single seat fighter could bomb with any accuracy from those heights? Could they hit (or even come close to) a specific target?
> 
> And what is likely to happen to those Spitfires climbing from 20000' up to even 25000' where the fighter bombers were, not to mention the reported 30000' where their escort was? In the four minutes that they have to intercept don't you think that those planes or the escort above will see the Spitfires crawling up at less than 500fpm (vertical speed about 5.5mph, a little faster than walking). Aren't the escorts going to bounce the Spitfires from above? Seems like the ideal situation for the escorts, or even the FBs.
> 
> That seems crazy to me and I don't think the British were crazy. Not much interception going on there in my opinion. They weren't about to waste finite resources chasing fighter bombers at altitudes where any bombing accuracy at all was pure luck. Not then there are bomber formations at 20000' and under.


Christ you really do talk some crap, if you drop bombs you hit things, I have already posted that two hospitals were hit and elsewhere 13 people were killed by a random bomb. Did you not read Parks instruction, the Spitfires on patrol were to shield the Hurricanes and Spitfires climbing behind. 

You are incapable of reading absorbing or assimilating anything, thats why you never have no answer to anything but bang on day and night about the weight of am IFF transponder. Your post shows you havnt a clue, they were not on a cliff face or a ladder, they were in 3 dimensions, so time and separation are part of the discussion.

Now how about some answers to questions, not any more of your daft ill informed and considered opinions and doubts?

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## DerAdlerIstGelandet (Jul 6, 2021)

P-39 Expert said:


> Please give up on trying to educate me. I already have way more education than I can ever use. Thank you.

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## Thumpalumpacus (Jul 6, 2021)

33k in the air said:


> I remember that time when the world wondered where Task Force 34 was.



That was indeed the reference, to the padding in that message.


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## P-39 Expert (Jul 6, 2021)

pbehn said:


> Christ you really do talk some crap, if you drop bombs you hit things, I have already posted that two hospitals were hit and elsewhere 13 people were killed by a random bomb. Did you not read Parks instruction, the Spitfires on patrol were to shield the Hurricanes and Spitfires climbing behind.
> 
> You are incapable of reading absorbing or assimilating anything, thats why you never have no answer to anything but bang on day and night about the weight of am IFF transponder. Your post shows you havnt a clue, they were not on a cliff face or a ladder, they were in 3 dimensions, so time and separation are part of the discussion.
> 
> Now how about some answers to questions, not any more of your daft ill informed and considered opinions and doubts?


That's the problem, most bombs dropped from only 20000' by bombardiers flying medium bombers in formation didn't hit anything. Farmland, a lake, absolutely nothing of importance. You're taking one example of a bomb that happened to randomly hit a hospital when you have no idea what the bomber was actually aiming at. Formations of bombers had woeful hit rates and you think one fighter at 25000' will come anywhere near his target? Seriously?

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## pbehn (Jul 6, 2021)

P-39 Expert said:


> That's the problem, most bombs dropped from only 20000' by bombardiers flying medium bombers in formation didn't hit anything. Farmland, a lake, absolutely nothing of importance. You're taking one example of a bomb that happened to randomly hit a hospital when you have no idea what the bomber was actually aiming at. Formations of bombers had woeful hit rates and you think one fighter at 25000' will come anywhere near his target? Seriously?


You have already been posted the normal attack procedure for Jabo pilots this was obtained from pilots shot down by the RAF who did "take the bait". You consider you already have too much education, so you dont read anything at all, that is why talking to you is like arguing with pound of mince.

If you took the trouble to read the link I posted and compared it to the previously posted link to Park and Dowdings instructions you would have seen after Park introduced a system the losses inflicted on the LW climbed dramatically and RAF losses declined.

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## Thumpalumpacus (Jul 6, 2021)

London was an absolutely huge target even in 1940. Ray Charles could have hit it without a bombsight too. If, as you say, the point was to draw the RAF up into the fight, how does accuracy matter at all?

From a logical standpoint, you are arguing against yourself.

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## buffnut453 (Jul 6, 2021)

P-39 Expert said:


> That's the problem, most bombs dropped from only 20000' by bombardiers flying medium bombers in formation didn't hit anything. Farmland, a lake, absolutely nothing of importance. You're taking one example of a bomb that happened to randomly hit a hospital when you have no idea what the bomber was actually aiming at. Formations of bombers had woeful hit rates and you think one fighter at 25000' will come anywhere near his target? Seriously?



Can we please have a source for the statement that most bombs dropped from 20,000ft "didn't hit anything. Farmland, a lake, absolutely nothing of importance"?

Can you please provide a source for the doctrine or directives of ANY air force, anywhere, anytime which states that they should only intercept those enemy aircraft that have a chance of bombing something important?

Yet again, you are failing to even read any of the posts that other members are providing. Per 
A
 Andrew Arthy
post 2104, the Me109 bombers didn't necessarily bomb from 25,000ft. The SOP for at least one Staffeln was to dive to 16,000ft and drop. 

Again, you're ENTIRELY MISSING THE POINT....Fighter Command's responsibility was to DEFEND UK AIRSPACE FROM ENEMY AIRCRAFT. PERIOD. It doesn't matter if they came over in high-powered washing machines, the job of the Hurricanes and Spitfires was to intercept them. That's the purpose of gaining/maintaining air superiority.

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## FLYBOYJ (Jul 6, 2021)

Luftwaffe Nuisance Bombing Causes Casualties In London


British Pathe, the world's leading multimedia resource with a history stretching back over a century. The finest and most comprehensive archive of fabulous footage and stunning stills.




www.britishpathe.com

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## pbehn (Jul 6, 2021)

buffnut453 said:


> Can we please have a source for the statement that most bombs dropped from 20,000ft "didn't hit anything. Farmland, a lake, absolutely nothing of importance"?
> 
> Can you please provide a source for ANY air force which states that they should only intercept those enemy aircraft that have a chance of bombing something important?
> 
> Again, you're ENTIRELY MISSING THE POINT....Fighter Command's responsibility was to DEFEND UK AIRSPACE FROM ENEMY AIRCRAFT. PERIOD. It doesn't matter if they came over in high-powered washing machines, the job of the Hurricanes and Spitfires was to intercept them. That's the purpose of gaining/maintaining air superiority.


The new argument from mince head is that a bomb may have hit a hospital and another may have killed 13 people but since they couldnt guarantee doing that, it can all be dismissed. I personally think it is a great bet that the Jabo raids on London hit London more often than Bomber command raids on Berlin hit Berlin in the same era.

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## Milosh (Jul 6, 2021)

I am reminded of another Texan who stated that the Germans could have easily have invaded GB. Their warships would easily crush the RN. The German fleet included pre WW1 warships that were no longer capable of battle. Nothing could persuade him otherwise.


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## XBe02Drvr (Jul 6, 2021)

Milosh said:


> I am reminded of another Texan who stated that the Germans could have easily have invaded GB. Their warships would easily crush the RN. The German fleet included pre WW1 warships that were no longer capable of battle. Nothing could persuade him otherwise.


Such folks are worth their weight in entertainment value.

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## Greg Boeser (Jul 6, 2021)

You never know. They were able to run a battle group up the channel in broad daylight, so why not an entire invasion fleet? What could go wrong?

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## Milosh (Jul 6, 2021)

Greg Boeser said:


> You never know. They were able to run a battle group up the channel in broad daylight, so why not an entire invasion fleet? What could go wrong?


The sun wasn't shinning.


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## XBe02Drvr (Jul 6, 2021)

Milosh said:


> The sun wasn't shinning.


Isn't that the default Channel weather condition?


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## buffnut453 (Jul 6, 2021)

P-39 Expert said:


> Please give up on trying to educate me. I already have way more education than I can ever use. Thank you.



And yet you insist on trying to "educate" people about the P-39. If you're not willing to learn, why are you here? Or are you just interested in trolling?

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## pbehn (Jul 6, 2021)

buffnut453 said:


> And yet you insist on trying to "educate" people about the P-39. If you're not willing to learn, why are you here? Or are you just interested in trolling?


Having seen his posts on the P-39, most of his knowledge and education comes from this forum, once we have the weight of the IFF transponder and the gas stove cum cockpit heater it will all be complete.

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## pbehn (Jul 6, 2021)

XBe02Drvr said:


> Isn't that the default Channel weather condition?


A lot of the time France Spain Belgium Germany Netherlands and Italy are completely isolated by fog.

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## Shortround6 (Jul 6, 2021)

P-39 Expert said:


> Are you saying the additional weight came from structural strengthening sometime after production of the C model in time for the D model and P-400? According to your P-39C manual empty weight was 5016lbs. The P-400 weighed 5550lbs empty. That's a difference of 534lbs. 240lbs was the self sealing fuel tanks. The book "Cobra" shows "minor empty and useful load changes" in Jan '41 and "engine and fixed equipment weight increase" in June '41 with production beginning in July, but those changes only account for 165lbs. I don't know where the additional 129lbs came from. Maybe it WAS structural bracing.



I _think_ some of the weight was from bracing and/or thicker components. 
The weight difference is greater than it seems. the P-39C empty weight included the radio, the empty weight of the P-39D-1 did not.
I found how much the radio in the P-39C weighed. 43.3 lbs 
It was a different radio than used in the P-39D-1 or other US P-39s. This is the communications radio and not the IFF gear. The IFF gear was included in the 129lbs listed for the P-39D-1 but one website says the IFF gear weighed 45lbs. 
The communications radio weighed 91lbs. Don't know if anything was shared. 
Weights are for a complete radio set including the switch boxes in the cockpit.
The radio in the P-39D-1 was much longer ranged than the one in the P-39C, range is give as 130 miles at 10,000ft. 
The one in the P-39C could receive ground transmissions at 30-45 miles, the ground station could hear the aircraft at 10-20 miles. 

Some of the weight _might_ have been in stronger landing gear and/or different tires. The P-39C went between 7100 and 7300lbs full load (nothing external) compared to the 8368lbs of a P-39D-1 with 75 gallon drop tank. The load factor was not at max gross weight but at a lower "combat weight", this is my term. Like P-36s were rated with 105 gallons of fuel in the tanks (tank behind pilot not filled). But the landing gear/tires still had to handle the heavier loads. 
There are a few things that need changing as the weight of the plane goes up.

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## 33k in the air (Jul 6, 2021)

Thumpalumpacus said:


> That was indeed the reference, to the padding in that message.



Woohoo! I got one right.

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## 33k in the air (Jul 6, 2021)

buffnut453 said:


> It doesn't matter if they came over in high-powered washing machines . . .



High-powered washing machine . . . hmmm . . . a Brewster Buffalo with a Pratt & Whitney R-2800 engine?

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## wuzak (Jul 6, 2021)

Shortround6 said:


> I _think_ some of the weight was from bracing and/or thicker components.
> The weight difference is greater than it seems. the P-39C empty weight included the radio, the empty weight of the P-39D-1 did not.



The radio is included in empty weight for the P-39C but not the P39D?
That would make the difference between empty weights, when to the same equipment level, even greater than it appears?


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## GrauGeist (Jul 6, 2021)

Not sure what gauge of wire was used for a typical USAAF transmitter, but they were high-powered output and should have required either 6 or 8-gauge stranded core supply wire from the battery to the transceiver assembly. When the radio transmitted, it would have had a booster motor that upped the transceiver's voltage/amps to transmit.
Just 20 feet of 8-gauge THHN wiring can weigh a few pounds and the motor assembly weighed about 12 pounds (at least the GE motors I worked with did) and the weight came from the iron core and copper windings in a cast aluminum housing.


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## Shortround6 (Jul 6, 2021)

wuzak said:


> The radio is included in empty weight for the P-39C but not the P39D?
> That would make the difference between empty weights, when to the same equipment level, even greater than it appears?


that is correct.


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## Shortround6 (Jul 6, 2021)

GrauGeist said:


> Not sure what gauge of wire was used for a typical USAAF transmitter, but they were high-powered output and should have required either 6 or 8-gauge stranded core supply wire from the battery to the transceiver assembly. When the radio transmitted, it would have had a booster motor that upped the transceiver's voltage/amps to transmit.
> Just 20 feet of 8-gauge THHN wiring can weigh a few pounds and the motor assembly weighed about 12 pounds (at least the GE motors I worked with did) and the weight came from the iron core and copper windings in a cast aluminum housing.


 weight for the radios includes most parts but not wiring. 
see.

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## FLYBOYJ (Jul 6, 2021)

Shortround6 said:


> weight for the radios includes most parts but not wiring.
> see.
> View attachment 631419


You beat me to the punch. I'm going to conservatively guess you're looking at between 35 - 50 pounds of wiring in a conduit.

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## buffnut453 (Jul 6, 2021)

33k in the air said:


> High-powered washing machine . . . hmmm . . . a Brewster Buffalo with a Pratt & Whitney R-2800 engine?



I understand it gave the whitest whites...and had a wicked spin cycle.

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## GrauGeist (Jul 6, 2021)

Wow...look at the weight of that dynamotor!
The ones I'm used to were half that weight.
But yes, wiring harnesses have considerable weight. The control cable between the TX/RX and the controlhead will be hefty because of the bundled wiring, RFI/ground shielding, the paper dividers and the outer cover, which back then, was rubberized. Plus the nickle (or silver) plated brass Amphenol plugs on either end.


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## ThomasP (Jul 6, 2021)

re the weights of the radios and IFF

"Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)"

Total fighter(bomber) installation weight of the SCR-522 set was ~105(125) lbs
Total fighter installation weight of the usual 2xtransmitter/3xreceiver SCR-274 set was ~100 lbs

Total fighter installation weight for IFF varied a bit, but they ranged from about 50 lbs for a SCR-535 IFF Mk II to about 60 lbs for the SCR-595 IFF Mk IIIG sets with additional transponder unit for G-band frequency.

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## Thumpalumpacus (Jul 7, 2021)

GrauGeist said:


> Not sure what gauge of wire was used for a typical USAAF transmitter, but they were high-powered output and should have required either 6 or 8-gauge stranded core supply wire from the battery to the transceiver assembly. When the radio transmitted, it would have had a booster motor that upped the transceiver's voltage/amps to transmit.
> Just 20 feet of 8-gauge THHN wiring can weigh a few pounds and the motor assembly weighed about 12 pounds (at least the GE motors I worked with did) and the weight came from the iron core and copper windings in a cast aluminum housing.



An increased range implies a larger power transformer for the amp as well, and that's already one of the heaviest pieces in the rig. And the weight rises disproportionate to the output in amps from this era.

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## Glider (Jul 7, 2021)

P-39 Expert said:


> Please give up on trying to educate me. I already have way more education than I can ever use. Thank you.


I don't suppose you would like to enlighten us with your qualifications and experience would you?

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## GrauGeist (Jul 7, 2021)

Thumpalumpacus said:


> An increased range implies a larger power transformer for the amp as well, and that's already one of the heaviest pieces in the rig. And the weight rises disproportionate to the output in amps from this era.


Early transmitters used lower frequencies with elevated wattage to be able to transmit over long distances.

Even today, the California Highway Patrol's TX/RX is in the 47MHz range with a TX output of about 150watts - that's enough power to cook a hotdog skewered on the antenna after a "ten count".

(don't ask me how I know, I'll disavow any knowledge of such things...)

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## XBe02Drvr (Jul 7, 2021)

GrauGeist said:


> When the radio transmitted, it would have had a booster motor that upped the transceiver's voltage/amps to transmit.


Not to mention the motor/generator style inverter to supply the 115V 400 Hz current some of the flight instruments and most of the radio gear required. The one in our club's T34 weighed 31 pounds bare and 35 with mounting bracket and wiring. The plane was built in the early 50s with all tube radios, but ours used "modern" Bendix 12VDC nav/coms. The only items that still used 115VAC/400Hz were the three gyros and their synchros.

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## P-39 Expert (Jul 7, 2021)

buffnut453 said:


> Can we please have a source for the statement that most bombs dropped from 20,000ft "didn't hit anything. Farmland, a lake, absolutely nothing of importance"?
> 
> Can you please provide a source for the doctrine or directives of ANY air force, anywhere, anytime which states that they should only intercept those enemy aircraft that have a chance of bombing something important?
> 
> ...


Throughout the war British area bombing and AAF pinpoint bombing never exceeded 50% of bombs landing within a THREE MILE radius of the target (Wiki). The BoB was before most of the British and AAF bombing.


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## pbehn (Jul 7, 2021)

P-39 Expert said:


> Throughout the war British area bombing and AAF pinpoint bombing never exceeded 50% of bombs landing within a THREE MILE radius of the target (Wiki). The BoB was before most of the British and AAF bombing.


Can you compare to daylight bombing? I believe the British destroyed many barges in ports along the French and Belian coast during the Battle of Britain while the USA managed to bomb the wrong country in 1945. Everyone can select their own factoids cant they? Irritating isnt it?

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## buffnut453 (Jul 7, 2021)

P-39 Expert said:


> Throughout the war British area bombing and AAF pinpoint bombing never exceeded 50% of bombs landing within a THREE MILE radius of the target (Wiki). The BoB was before most of the British and AAF bombing.



So you're taking an average across all daylight and night-time bombing efforts? Yeah, not the most relevant of statistics. However, let's use your 3-mile figure just for grins to show the irrelevance of your statement.

Per the Wiki page on the Blitz (The Blitz - Wikipedia), the size of London in 1940 was about 750 square miles (it held about one-fifth of the population of Britain). Treating that area as a circle, just to keep things simple, gives us a radius of about 15.4 miles from the centre of London to its edge. If the aim point for the Jabo raids is the centre of the city then, per your statistic, 50% of all the bombs would fall within 3 miles....but that still leaves 12.4 miles of London's radius for the remainder to fall in. Thus, for a large area target like London, the vast majority of the Jabo bombs would hit "something"...not farmland, not lakes, but people, property, industry, businesses, government etc. Again, why would Fighter Command ignore that threat? Still awaiting an answer on that.

But wait...there's more. The Jabo raids didn't only bomb from 20,000 ft. Per this site (Jabo over England I), high-altitude attacks were only used against large area targets like cities. Even then, the Me109 fighter-bombers would dive to improve weapon aiming, a tactic that was mentioned earlier in this thread. Attacks against point targets employed low-level bombing at 1000-1500ft were employed which would greatly increase the precision and accuracy of those attacks....but just because you bomb at low-level does NOT mean the entire sortie was flown at low level. Hi-lo-hi is a very common ground attack flight profile against which FC had to respond.

So...back at you again. Please explain why FC was wrong to intercept these raids.

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## Just Schmidt (Jul 7, 2021)

P-39 Expert said:


> Throughout the war British area bombing and AAF pinpoint bombing never exceeded 50% of bombs landing within a THREE MILE radius of the target (Wiki). The BoB was before most of the British and AAF bombing.


Honestly, this is getting increasingly silly, to use a good old British word including, if not synonymous with, groundhuggery.

Firstly, if the best source you can come up with is wiki, it can either means that somebody wrote something wrong or out of context on wiki, or that you are too lazy to find something better. It cannot be the final word. After weeks of debating this, you really ought to be able to come up with something more definite. Even as it stands ,half the bombs landing within three miles of an aiming point in the middle of London will worry civilians and authorities, and the purpose of bombing London was not only pin pricking munition factories and docks, but also to strike terror into the population.

Secondly and a pro pos words. Never is is a very big word, did wiki qualify what it meant? Over any three month period of bombing? The whole war as an average? On any single mission? Did it even specify from which height the bombing in its 'sample' took place? As it stands, by implication by 'British area bombing' we are not only talking about high level bombing any more, surely you don't wish to argue that no interception is worth the effort? So second and a halfly, this reference to wiki is neither here nor there.

Thirdly, did those in charge in the bob know what we know? Can we use our hindsight to trump what the decision makers at the time knew or thought they knew? They percieved a threat and wished to be able to counter it. And they could not know at what heights future combat would take place, but the trend seemed to be rising. Neither could they know for certain what numbers or what kind of planes Germany would produce in the years to come, if memory serves the Fw 190 came as a complete surprize. Hell, two weeks ago I didn't realize I needed a word like groundhuggery.

fourthly, the threat from high flying aircraft was not only bombing. Italy is the only major combatant of which I have no positive knowledge of any actual development of at least prototypes of high attitude fighters. The Ju- 86 may have had the ability to carry a few bombs, but the real significance of the plane was its ability to gather intelligence. a concept not to be dismissed. While we can only speculate it is fair to assume that could Germany have photographed the build up to Overlord, the operation may have proved far more costly. I know about those things called clouds, but before you quote some Englishman that it always rains over all of England (hint, you can find him on this very forum), I will only budge if presented with hard metereological data that this was in fact the case from some point in 1943 to mid 1944.

This has had us all cringing for quite a while now. I'm not advocating this thread be closed, nobody is forced to watch a train wreck. But I think we're learning something about human psychology as well, as we watch ourselves typing into this black hole. There is also a warning in the title, that said we may consider adding: "may contain nuts."

I know I'm not the one here who thinks least about the P-39, but I don't think that you're doing it any favours right now either. It becomes increasingly difficult to discern between the plane and its advocate. This is a strange fight to pick, though by no means all, some of your previous contributions have had far more value than this.

This is just ridiculous.

As you have yourself pointed out you're always respectful in the way you write your posts, though sometimes the repetition of certain them and failing to reply to certain posts implies disrespect. Even then you don't spell it out in the same way as some of your opponents here, though I must admit that sometimes I understand their exasperation. As humans we're all fallible and we all make mistakes from time to time, and we can all be affected by tunnel vision. I'm not saying that you are silly in general, but your recent posting in this thread surely has been.

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## Peter Gunn (Jul 7, 2021)

SaparotRob said:


> I really got to hand it to a couple of our posters. I try to come up with patently ridiculous claims for an absurd position and I run out of steam. I don't know how they do it.


It's a talent.

Also on that note, I hunker down for a hurricane, which turned out to be a tropical storm, lots of rain, not much wind and you guys have run out three more pages of posts. Now THAT'S talent.



GregP said:


> Hey, I think I KNOW that cop you're talking about above ...


I know right? My first Rat motored Chevelle but it was one of the County Sheriff's daughters...

Which sounds a lot more interesting/exciting than reality but it makes for a good cliff hanger to pique interest.

Our High Sheriff had three daughters, all of them lookers, it was the middle one that liked fast cars.

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## Peter Gunn (Jul 7, 2021)

SaparotRob said:


> It's already been posted here that rearward c.o.g. doesn't affect performance.


Well the unspoken issue would be the reduction of range, dragging your a... tailpipes will negatively effect fuel consumption. How can you not admit some of these simple cardynamic issues?

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## SaparotRob (Jul 7, 2021)

Peter Gunn said:


> Well the unspoken issue would be the reduction of range, dragging your a... tailpipes will negatively effect fuel consumption. How can you not admit some of these simple cardynamic issues?


Like I said, I don't know how they do it.

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## pbehn (Jul 7, 2021)

Just Schmidt said:


> Great post
> fourthly, the threat from high flying aircraft was not only bombing. Italy is the only major combatant of which I have no positive knowledge of any actual development of at least prototypes of high attitude fighters. The Ju- 86 may have had the ability to carry a few bombs, but the real significance of the plane was its ability to gather intelligence. a concept not to be dismissed. While we can only speculate it is fair to assume that could Germany have photographed the build up to Overlord, the operation may have proved far more costly. I know about those things called clouds, but before you quote some Englishman that it always rains over all of England (hint, you can find him on this very forum), I will only budge if presented with hard meteorological data that this was in fact the case from some point in 1943 to mid 1944.


In reading stuff for the other groundhog thread and stuff I remember from here and there the deception plan Fortitude for D-Day was interesting. It is impossible to guarantee that no recon planes would get over south England so they prepared for such a plane to find what was expected to be there. The fictitious army in Kent under Patton had inflatable tanks and aircraft out in the open. The real army to the west, all over the countryside north of Southampton and Portsmouth were heavily camouflaged/ disguised. Naval assets around Portsmouth and Southampton would be a logical holding place for action in the Pas de Calais. So the intention was that any recon that happened would confirm what was wanted to confirm, the Landing would be in Calais.

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## Milosh (Jul 7, 2021)

Old saying: You can lead a horse to water but you can`t make it drink.

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## FLYBOYJ (Jul 7, 2021)

Milosh said:


> Old saying: You can lead a horse to water but you can`t make it drink.


or "I give you books and you eat the covers"!

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## pbehn (Jul 7, 2021)

buffnut453 said:


> So you're taking an average across all daylight and night-time bombing efforts? Yeah, not the most relevant of statistics. However, let's use your 3-mile figure just for grins to show the irrelevance of your statement.
> 
> Per the Wiki page on the Blitz (The Blitz - Wikipedia), the size of London in 1940 was about 750 square miles (it held about one-fifth of the population of Britain). Treating that area as a circle, just to keep things simple, gives us a radius of about 15.4 miles from the centre of London to its edge. If the aim point for the Jabo raids is the centre of the city then, per your statistic, 50% of all the bombs would fall within 3 miles....but that still leaves 12.4 miles of London's radius for the remainder to fall in. Thus, for a large area target like London, the vast majority of the Jabo bombs would hit "something"...not farmland, not lakes, but people, property, industry, businesses, government etc. Again, why would Fighter Command ignore that threat? Still awaiting an answer on that.
> 
> ...


In two of the pictured Bf109s in the link they are carrying 4x 110Lb bombs, a third of Bf109 Jabos were this type so it isnt certain that they were only dropping one 550Lb bomb.

There was no "standard" raid procedure, each group had its own Jabo aircraft and what they did depended entirely on the weather.

Goering had over 500Bf 109s in the area, one third were made or converted into Jabos,, if the RAF made no attempt to intercept any Jabo raid they would all very quickly become Jabo aircraft.

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## SaparotRob (Jul 7, 2021)

Milosh said:


> Old saying: You can lead a horse to water but you can`t make it drink.


You can force me to school but you can't make me think.

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## FLYBOYJ (Jul 7, 2021)

The beat goes on...

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## GrauGeist (Jul 7, 2021)

"Teacher, leave those kids alone!"
_- P. Floyd, 1980_

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## pbehn (Jul 7, 2021)

SaparotRob said:


> You can force me to school but you can't make me think.


There is real comedy in referring to a British bombing survey to argue that people who were bombed in London should relax, because the bomb wasnt actually aimed at their house. Like telling someone attacked by a hippo that they are herbivores.

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## 33k in the air (Jul 7, 2021)

P-39 Expert said:


> Throughout the war British area bombing and AAF pinpoint bombing never exceeded 50% of bombs landing within a THREE MILE radius of the target (Wiki).



The general benchmark for accuracy for Bomber Command was percentage of bombs within three miles of the aiming point. The percentage achieved varied considerably during the war as it was dependent on many factors. The overall value improved as the war went on.

In 1942 and through April 1943, the six-month average was about 25%. The introduction of H2S, Oboe, and Master Bombers raised the figure to about 55% from June through the rest of 1943. Starting in June 1944, the figure showed a steady upward trend, with rate topping 90% in 1945.

See the graph "Accuracy of Night Bombing of German Cities (Excluding Berlin)" on page 659 of _The Crucible of War 1939-1945_ by Brereton Greenhous, Stephen J. Harris, William C. Johnston, and William G.P. Rawling.

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## buffnut453 (Jul 7, 2021)

GrauGeist said:


> "Teacher, leave those kids alone!"
> _- P. Floyd, 1980_



That's precisely why I wear a tinfoil hat...because we don't need no thought control!

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## pbehn (Jul 7, 2021)

33k in the air said:


> The general benchmark for accuracy for Bomber Command was percentage of bombs within three miles of the aiming point. The percentage achieved varied considerably during the war as it was dependent on many factors. The overall value improved as the war went on.
> 
> In 1942 and through April 1943, the six-month average was about 25%. The introduction of H2S, Oboe, and Master Bombers raised the figure to about 55% from June through the rest of 1943. Starting in June 1944, the figure showed a steady upward trend, with rate topping 90% in 1945.
> 
> See the graph "Accuracy of Night Bombing of German Cities (Excluding Berlin)" on page 659 of _The Crucible of War 1939-1945_ by Brereton Greenhous, Stephen J. Harris, William C. Johnston, and William G.P. Rawling.


Almost all the factors needed to increase bombing accuracy London had. It is close, near the coast, has a very distinctive river and by day many unique large buildings, it is an ideal target by day or night.


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## 33k in the air (Jul 7, 2021)

P-39 Expert said:


> Throughout the war British area bombing and AAF pinpoint bombing never exceeded 50% of bombs landing within a THREE MILE radius of the target (Wiki).



Additional point on accuracy from _The Crucible of War 1939-1945_ by Brereton Greenhous, Stephen J. Harris, William C. Johnston, and William G.P. Rawling, page 794.

_From April 1 [1944] on, however, although area raids would continue to be mounted, High Wycombe's effort would increasingly be in support of Operation Overlord. In this respect there could be little doubt that, with bombing errors generally running less than seven hundred yards, the nine March raids on French railway targets had been outstandingly successful --- demonstrating, at times, 'an accuracy and concentration . . . far exceeding that . . . achieved by the American heavies by day.'*

* After the war, the United States Strategic Bombing Survey estimated that, bombing visually by day in clear weather, the Eighth Air Force was able to get half its bombs within one-third of a mile of the aiming point; bombing non-visually by day, in heavy cloud, it got only one-half its bombs within 3.9 miles of the aiming point._

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## P-39 Expert (Jul 7, 2021)

buffnut453 said:


> So you're taking an average across all daylight and night-time bombing efforts? Yeah, not the most relevant of statistics. However, let's use your 3-mile figure just for grins to show the irrelevance of your statement.
> 
> Per the Wiki page on the Blitz (The Blitz - Wikipedia), the size of London in 1940 was about 750 square miles (it held about one-fifth of the population of Britain). Treating that area as a circle, just to keep things simple, gives us a radius of about 15.4 miles from the centre of London to its edge. If the aim point for the Jabo raids is the centre of the city then, per your statistic, 50% of all the bombs would fall within 3 miles....but that still leaves 12.4 miles of London's radius for the remainder to fall in. Thus, for a large area target like London, the vast majority of the Jabo bombs would hit "something"...not farmland, not lakes, but people, property, industry, businesses, government etc. Again, why would Fighter Command ignore that threat? Still awaiting an answer on that.
> 
> ...


Bombing doesn't target a city, it targets a specific factory, power plant, refinery, etc. 

If the jabos get any lower than 20000' they will be easy to intercept since they will be a lot slower due to the attached 550lb bomb.

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## fubar57 (Jul 7, 2021)

Hamburg....Coventry

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## SaparotRob (Jul 7, 2021)

So area bombing wasn't a thing?

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## buffnut453 (Jul 7, 2021)

P-39 Expert said:


> Bombing doesn't target a city, it targets a specific factory, power plant, refinery, etc.
> 
> If the jabos get any lower than 20000' they will be easy to intercept since they will be a lot slower due to the attached 550lb bomb.



*"Bombing doesn't target a city, it targets a specific factory, power plant, refinery, etc." *Really? So what do you make of the UK's "Area Bombing Directive" by which Bomber Command was tasked to attack cities rather than targeting specific facilities? The link I included about Jabos specifically differentiates between "area targets" and "point targets" where the area target is a city. Bombing and targeting are not synonyms. 

*"If the jabos get any lower than 20000' they will be easy to intercept since they will be a lot slower due to the attached 550lb bomb." * Really? So the Jabo dives, gaining speed, releases the bomb, and then continues to dive, at higher speed, to get away....that makes them MORE vulnerable? Certainly the fighter bomber will be less manoeuvrable while carrying the bomb but speed, particularly in a dive, won't be impacted that much. To say they would be "easy to intercept" also ignores the fact that the Jabos were escorted...you keep ignoring this fact.

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## P-39 Expert (Jul 7, 2021)

Just Schmidt said:


> Honestly, this is getting increasingly silly, to use a good old British word including, if not synonymous with, groundhuggery.
> 
> Firstly, if the best source you can come up with is wiki, it can either means that somebody wrote something wrong or out of context on wiki, or that you are too lazy to find something better. It cannot be the final word. After weeks of debating this, you really ought to be able to come up with something more definite. Even as it stands ,half the bombs landing within three miles of an aiming point in the middle of London will worry civilians and authorities, and the purpose of bombing London was not only pin pricking munition factories and docks, but also to strike terror into the population.
> 
> ...


Wiki's information is from the Strategic Bombing Survey.

BoB has nothing to do with the P-39. Most all the information I quote on here is from wwiiaircraftperformance.org.

All if have said is that 109E fighter bombers couldn't get above 25000' so by definition they couldn't have fought at 30000'.

And I don't think there was a significant amount of combat at 30000'. Just my opinion based on capabilities of the planes involved.


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## buffnut453 (Jul 7, 2021)

P-39 Expert said:


> Wiki's information is from the Strategic Bombing Survey.
> 
> BoB has nothing to do with the P-39. Most all the information I quote on here is from wwiiaircraftperformance.org.
> 
> ...



*All if have said is that 109E fighter bombers couldn't get above 25000' so by definition they couldn't have fought at 30000'. *But the escorting Bf109s could get to 30,000ft and did fight there.
*
BoB has nothing to do with the P-39. *But the whole reason we disappeared down this rabbit-hole is because you claimed that air combat over Western Europe was the same as air combat over Eastern Europe. You were then presented with plenty of evidence that the former took place at higher altitudes than the latter...but you keep ignoring the evidence and returning to your opinion-centric statements.

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## pbehn (Jul 7, 2021)

P-39 Expert
you have already been told what interviewed Jabo pilots procedure was so why are you changing it. How do you target a refinery? I have lived near many most of my life and worked on them in the middle east, they are bigger than some cities. Your ideas on bombing are your ideas and feelings to suit your agenda they are not facts. Please preface your ideas and feelings as what they are.


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## pbehn (Jul 7, 2021)

P-39 Expert said:


> Wiki's information is from the Strategic Bombing Survey.
> 
> BoB has nothing to do with the P-39. Most all the information I quote on here is from wwiiaircraftperformance.org.
> 
> ...


It is only you that made this your game winning argument, you originally claimed no BoB aircraft could get to that height, inn fact they all could, it was just a matter of time. What you think about levels of combat doesn't matter, bearing in mind what Dowding said. Why do you thing your feelings and thoughts are more important than facts?

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## FLYBOYJ (Jul 7, 2021)

P-39 Expert said:


> Bombing doesn't target a city, it targets a specific factory, power plant, refinery, etc.


Boy. for all the armchair aviation and military training you have, you seem to be unaware (or choose to ignore) that some *nuisance* *raids* were undertaken just to piss off the population, keep people up at night, expend emergency services, stretch defenses and finally diminish the will of the people to continue to fight (at least that's the ultimate goal). If you lob a few bombs over the CITY of London, you're going to achieve most of this objective, it doesn't matter what you hit. A poster quoted several pilots who flew these raids along with sources. Please, this is going from silliness to stupidity.

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## DerAdlerIstGelandet (Jul 7, 2021)

pbehn said:


> P-39 Expert
> you have already been told what interviewed Jabo pilots procedure was so why are you changing it. How do you target a refinery? I have lived near many most of my life and worked on them in the middle east, they are bigger than some cities. Your ideas on bombing are your ideas and feelings to suit your agenda they are not facts. Please preface your ideas and feelings as what they are.



But were any of those Jabo pilots by any chance Chuck Jaeger?

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## GrauGeist (Jul 7, 2021)

P-39 Expert said:


> Just my opinion


Which means squat in the face of actual facts that have been provided in multitude.

And by multitude, I means hundreds of posts...

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## pbehn (Jul 7, 2021)

SaparotRob said:


> So area bombing wasn't a thing?


If you look at this map which shows all the bomb hits in London, n places you can see 8 hits in a line. A Heinkel He111 releasing 8 bombs pointy end upwards was going to hit a long line not a point. Only special aircraft with special bombs and crews could target an individual point. Even dive bombers frequently missed, but by less than others. Bomb Sight - Mapping the London Blitz

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## pbehn (Jul 7, 2021)

DerAdlerIstGelandet said:


> But were any of those Jabo pilots by any chance Chuck Jaeger?


Obviously not, London as we know it would not exist, all its landmarks would have been flattened.

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## DerAdlerIstGelandet (Jul 7, 2021)

DerAdlerIstGelandet said:


> But were any of those Jabo pilots by any chance Chuck Jaeger?



In case anyone is wondering, the misspelling was on purpose.

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## pbehn (Jul 7, 2021)

FLYBOYJ said:


> Boy. for all the armchair aviation and military training you have, you seem to be unaware (or choose to ignore) that some *nuisance* *raids* were undertaken just to piss off the population, keep people up at night, expend emergency services, stretch defenses and finally diminish the will of the people to continue to fight (at least that's the ultimate goal). If you lob a few bombs over the CITY of London, you're going to achieve most of this objective, it doesn't matter what you hit. A poster quoted several pilots who flew these raids along with sources. Please, this is going from silliness to stupidity.


By only discussing daylight raids, sight is lost of it being a combined offensive on London. From 7 September London was bombed 57 consecutive nights, daytime Jabo raids started shortly after. The daytime raids discussed in October are in the middle of that period, after a night of bombing it is much more than a nuisance to make everyone take to the air raid shelters for most of the day, in fact it is impossible, people were trapped in buildings and water and gas mains were damaged etc. The idea that the LW would be given a free hit to continue this indefinitely (there was no effective night time defence) is beyond preposterous.

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## SaparotRob (Jul 7, 2021)

I was afraid to say anything.


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## fubar57 (Jul 7, 2021)

Was there ever a study about how accurate Luftwaffe bombing was, not counting Ju 87s and other diving bombers?


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## GrauGeist (Jul 7, 2021)

fubar57 said:


> Was there ever a study about how accurate Luftwaffe bombing was, not counting Ju 87s and other diving bombers?


Do flaming He111s and Do17s count?

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## pbehn (Jul 7, 2021)

fubar57 said:


> Was there ever a study about how accurate Luftwaffe bombing was, not counting Ju 87s and other diving bombers?


During the BoB era they were very good, many of the targets were easy to find and things like Knickebein were effective at the start of the battle of the beams. By the time of the Baby Blitz almost all experienced crews had been lost and night time defences had improved to the point that it was a sad waste of men and machines.

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## pbehn (Jul 7, 2021)

SaparotRob said:


> I was afraid to say anything.


Just give us your feelings, only feelings matter.


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## pbehn (Jul 7, 2021)

DerAdlerIstGelandet said:


> In case anyone is wondering, the misspelling was on purpose.


I did wonder.


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## DerAdlerIstGelandet (Jul 7, 2021)

pbehn said:


> I did wonder.



Jabo...

Jagd...

Yaeger...

Jaeger.

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## XBe02Drvr (Jul 7, 2021)

DerAdlerIstGelandet said:


> In case anyone is wondering, the misspelling was on purpose.


I saw what you did.

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## pbehn (Jul 7, 2021)

DerAdlerIstGelandet said:


> Jabo...
> 
> Jagd...
> 
> ...


My only other use of the name Jaeger which was very often was in reference to colour charts for eye tests.


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## XBe02Drvr (Jul 7, 2021)

DerAdlerIstGelandet said:


> Jabo...
> 
> Jagd...
> 
> ...


They forgot how to spell in WV. Betcha his ancestors spelled it your way.

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## 33k in the air (Jul 7, 2021)

DerAdlerIstGelandet said:


> But were any of those Jabo pilots by any chance Chuck Jaeger?



He should have been the star of _Pacific Rim_.


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## Thumpalumpacus (Jul 7, 2021)

Peter Gunn said:


> It's a talent.
> 
> Also on that note, I hunker down for a hurricane, which turned out to be a tropical storm, lots of rain, not much wind and you guys have run out three more pages of posts. Now THAT'S talent.



Stay safe, PG!



Just Schmidt said:


> I know I'm not the one here who thinks least about the P-39, but I don't think that you're doing it any favours right now either. It becomes increasingly difficult to discern between the plane and its advocate.



This is very apt. When tunnel-vision obscures facts, and results in regarding one's own opinions as more regnant than, say, the folks who fought the battle, that's a clear sign that there's some bias in play.

A true expert acknowledges other views in his field of expertise, not only to dismiss them, but as well to regard them and perhaps add facts into his portfolio. Writing anything like " I need no more education" is usually a sign that certitude has overtaken learning.

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## Thumpalumpacus (Jul 7, 2021)

Milosh said:


> Old saying: You can lead a horse to water but you can`t make it drink think.



My own take on this adage, after years on the 'Net.

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## buffnut453 (Jul 7, 2021)

GrauGeist said:


> Do flaming He111s and Do17s count?



He111s and Do17s are bombers which, by definition, CANNOT be flaming because it's always the fighters that are flaming while bombers are bloody (to whit the words of the immortal Michael Caine, "Leave the flaming fighters it's the bloody bombers we want!").

You are SUCH an AMATEUR!!!!

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## buffnut453 (Jul 7, 2021)

Thumpalumpacus said:


> Stay safe, PG!
> 
> 
> 
> ...



Bacon awarded for the first use of "regnant" that I've seen on this forum. Bravo, sir!!!

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## nuuumannn (Jul 7, 2021)

DerAdlerIstGelandet said:


> In case anyone is wondering, the misspelling was on purpose.



Surely it's Karl Elwald von Jaeger...


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## SaparotRob (Jul 7, 2021)

pbehn said:


> Just give us your feelings, only feelings matter.


I felt he misspelled Yayger.

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## Thumpalumpacus (Jul 7, 2021)

buffnut453 said:


> Bacon awarded for the first use of "regnant" that I've seen on this forum. Bravo, sir!!!



Thank you, sir!

I've been told I'm a cunning linguist, your support heartens me.

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## GrauGeist (Jul 7, 2021)

buffnut453 said:


> He111s and Do17s are bombers which, by definition, CANNOT be flaming because it's always the fighters that are flaming while bombers are bloody (to whit the words of the immortal Michael Caine, "Leave the flaming fighters it's the bloody bombers we want!").
> 
> You are SUCH an AMATEUR!!!!


How about flaming bloody bombers, then?

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## Greg Boeser (Jul 7, 2021)

buffnut453 said:


> That's precisely why I wear a tinfoil hat...because we don't need no thought control!


Actually, chicken wire of sufficient gauge will do the trick.

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## buffnut453 (Jul 7, 2021)

GrauGeist said:


> How about flaming bloody bombers, then?



I guess you could use that to describe the Jabos!

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## buffnut453 (Jul 7, 2021)

Greg Boeser said:


> Actually, chicken wire of sufficient gauge will do the trick.



Yes, but it's so much easier to shape tinfoil into stylish designs:

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## pbehn (Jul 7, 2021)

SaparotRob said:


> I felt he misspelled Yayger.


I knew he deliberately misspelled the name out of respect for who he was, simply because Adler is a German speaker. I dont appreciate combat aces being dragged into this when they are not here to comment, especially when other combat aces are dismissed as "joe pilot". Chuck was a famous aviator, also famous for not really liking the British, however that doesnt mean he would think using a P-39 to intercept Jabo formations at 30,000ft is a good idea in any year of the war.

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## pbehn (Jul 7, 2021)

Greg Boeser said:


> Actually, chicken wire of sufficient gauge will do the trick.


How much does chicken wire weigh? Would it be useful on a P-39 radio as far as dry weight is concerned?


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## nuuumannn (Jul 7, 2021)

fubar57 said:


> Was there ever a study about how accurate Luftwaffe bombing was, not counting Ju 87s and other diving bombers?



Probably somewhere. When RV Jones was researching his theory about German use of radio signals to guide the bombers, which he was spot-on about, after a raid on a factory in Birmingham the pattern of the impact of the bombs demonstrated very good accuracy for the time, although accuracy was highly subjective and was, compared to later in the war not as good. There is an illustration of the bomb plots in his book Most Secret War. From the bomb plots they were able to ascertain where the X Gerat cross beams timed when bomb release took place based on where they fell, pretty much in a straight line directly over the target, although there were two lines of bombs some distance either side of the target, which Jones after the war queried German scientists on that they had no idea why there were shadow signals that led to three lines of bombs being dropped.

Nevertheless, when attacking pinpoint targets the system worked very well, but the Germans concentrated on bombing city centres, like Coventry and London, when they had a very accurate means of attacking pinpoint targets, which in hindsight, they could have done more of. This is why I have said in the past in other threads that I believe the Kampfgeschwader to be the most accurate and best bombing force at the beginning of WW2. No other air force could match the level of accuracy nor ratio of aircraft and thus bombs over the target area as the Luftwaffe. It took the RAF and USAAF a couple of years to get to the same degree of accuracy as what the Luftwaffe had in its hands in 1939/1940.

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## nuuumannn (Jul 7, 2021)

Thumpalumpacus said:


> Stay safe, PG!



Agree, man, keep your head down and your loved ones close.

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## SaparotRob (Jul 7, 2021)

Thumpalumpacus said:


> Thank you, sir!
> 
> I've ben told I'm a cunning linguist, your support heartens me.


I see what you did there.

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## pbehn (Jul 7, 2021)

nuuumannn said:


> Probably somewhere. When RV Jones was researching his theory about German use of radio signals to guide the bombers, which he was spot-on about, after a raid on a factory in Birmingham the pattern of the impact of the bombs demonstrated very good accuracy for the time, although accuracy was highly subjective and was, compared to later in the war not as good. There is an illustration of the bomb plots in his book Most Secret War. From the bomb plots they were able to ascertain where the X Gerat cross beams timed when bomb release took place based on where they fell, pretty much in a straight line directly over the target, although there were two lines of bombs some distance either side of the target, which Jones after the war queried German scientists on that they had no idea why there were shadow signals that led to three lines of bombs being dropped.
> 
> Nevertheless, when attacking pinpoint targets the system worked very well, but the Germans concentrated on bombing city centres, like Coventry and London, when they had a very accurate means of attacking pinpoint targets, which in hindsight, they could have done more of. This is why I have said in the past in other threads that I believe the Kampfgeschwader to be the most accurate and best bombing force at the beginning of WW2. No other air force could match the level of accuracy nor ratio of aircraft and thus bombs over the target area as the Luftwaffe. It took the RAF and USAAF a couple of years to get to the same degree of accuracy as what the Luftwaffe had in its hands in 1939/1940.


Taking an average makes no sense. The raid on Coventry showed how devastating a raid could be with guidance like Knickebein, but once the beams were bent they were equally not devastating at all. At the start of the BoB there was no defence other than pilots going up and hoping to get lucky. Efforts were made with using fighters around searchlights but the BoB was over before effective aircraft carrying RADAR came into use. Wiki isnt a great source but in this link table sorties flown shows between October 1940 and May 1941 night sorties went from 5,900 with 23 lost to 3,800 with 55 lost. So a 30% reduction in operations and more than double the losses.


The Blitz: estimated _Luftwaffe_ bomber sorties.[119]​


Month/yearDay sorties (losses)Night sorties (losses)_Luftflotte_ 2 sorties_Luftflotte_ 3 sortiesMajor attacksHeavy attacksOctober 19402,300 (79)5,900 (23)2,4003,500254November 1940925 (65)6,125 (48)1,6004,525232December 1940650 (24)3,450 (44)7002,750115January 1941675 (7)2,050 (22)4501,60076February 1941500 (9)1,450 (18)475975–2March 1941800 (8)4,275 (46)1,6252,650123April 1941800 (9)5,250 (58)1,5003,750165May 1941200 (3)3,800 (55)1,3002,500113
​

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## buffnut453 (Jul 7, 2021)

SaparotRob said:


> I see what you did there.



I didn't...can you explain it to me, please?

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## nuuumannn (Jul 7, 2021)

pbehn said:


> Taking an average makes no sense. The raid on Coventry showed how devastating a raid could be with guidance like Knickebein, but once the beams were bent they were equally not devastating at all.



It depends, remembering that at the time Jones and his scientists were producing that information they still had not concluded that this was what the Germans were doing, so they needed as much raw data as they could get.

As for the effectiveness of the beams after they had been 'bent', that's irrelevant to how effective they were in practise _before_ they were bent. It's worth noting that the theory of using ground-mounted radio signals for navigation and guidance was similar in Gee and Oboe, so these were the logical successors to the German systems. That they were defeated was a matter of time, but that in no way discounts how effective they were.

Also, the Germans didn't just stop using the systems because the British developed countermeasures, the German raids against Britain failed due to a number of reasons, not least the quality of night fighters improving, but that's a different story.


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## pbehn (Jul 7, 2021)

nuuumannn said:


> It depends, remembering that at the time Jones and his scientists were producing that information they still had not concluded that this was what the Germans were doing, so they needed as much raw data as they could get.
> 
> As for the effectiveness of the beams after they had been 'bent', that's irrelevant to how effective they were in practise _before_ they were bent. It's worth noting that the theory of using ground-mounted radio signals for navigation and guidance was similar in Gee and Oboe, so these were the logical successors to the German systems. That they were defeated was a matter of time, but that in no way discounts how effective they were.
> 
> Also, the Germans didn't just stop using the systems because the British developed countermeasures, the German raids against Britain failed due to a number of reasons, not least the quality of night fighters improving, but that's a different story.


Sorry, maybe badly worded on my part. I meant taking an average across the whole war makes no sense for any force. Like the survey that said only half of British bombers got within 3 miles etc. A bombing survey will just tell you the bombs dropped where they were aimed. Hull became the most bombed place in UK by nights bombed not tonnage, it was the easiest place to find as a secondary target being on a headland north of the Humber. It was bombed so much there was no military value in bombing it anymore but as a secondary target it got hit time and again.


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## nuuumannn (Jul 7, 2021)

pbehn said:


> Sorry, maybe badly worded on my part. I meant taking an average across the whole war makes no sense for any force. Like the survey that said only half of British bombers got within 3 miles etc. A bombing survey will just tell you the bombs dropped where they were aimed. Hull became the most bombed place in UK by nights bombed not tonnage, it was the easiest place to find as a secondary target being on a headland north of the Humber. It was bombed so much there was no military value in bombing it anymore but as a secondary target it got hit time and again.



Quite possibly not, but surveys serve a purpose. The Butt Report (wot you referred to) confirmed what a few people already knew about how ineffective Bomber Command was; Ludlow-Hewitt had been going on about it in multiple memos prior to the war regarding how poor the RAF's navigation was but no one listened. It's a part of understanding how techniques in vogue are doing and if you can't review what you are doing, how can you expect to do better? This is why the Luftwaffe did so badly during the Battle of Britain, it had no way of accurately determining whether or not it was doing what it believed it was doing.

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## XBe02Drvr (Jul 7, 2021)

Thumpalumpacus said:


> " I need no more education" is usually a sign that certitude has overtaken learning.


I was taught that learning is a lifelong thing.
Stop learning = start dying.

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## pbehn (Jul 7, 2021)

XBe02Drvr said:


> I was taught that learning is a lifelong thing.
> Stop learning = start dying.


He needs someone to tell him what the 25 airframe mods were that grounded P-39s in UK in 1941 and also needs to know how much these mods weighed, once this is combined with the weight of an IFF transponder, his education will be complete, as a P-39 expert.

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## Shortround6 (Jul 7, 2021)

A connection can be drawn between the BoB and the P-39/P-400 in that the P-39 was no longer wanted by the British not because the the BoB was already over ( and Russian being invaded when they showed up) but because the P-39 no longer met the tactical requirements of the British. 

Operational altitudes had gone from 15,000-20,000 ft in the Battle of France to 25,000-30,000ft in the BoB in just 6 months. 
The British had introduced the Hurricane II with the Merlin XX and the Spitfire V with the Merlin 45 many months before the P-400 showed up. 

From Wiki " During a meeting held at the RAE at Farnborough on *17 February 1941* the Air Ministry asked "that a Spitfire should be provided with a pressure cabin capable of maintaining a pressure differential of 1 pound per square inch (69 hectopascals; 0.068 standard atmospheres) at 40,000 feet (12,000 m)."
Bolding is by me, this is 4 1/2 months before even the P-39C shows up in England. It is also about 2 1/2 months before Bell gets that tricked out 2nd production P-400 to barely make the qualifying speed for the contract. 
The British were afraid that operational altitudes would continue to climb. It turns out that they didn't or at least not as fast as the British thought they would. Making aircraft work at 35-40,000 ft was somewhat harder than adding a very weak pressure cabin and small compressor. Germans found out the same thing. 

But in the summer and fall of 1941 the threat of higher altitude combat was thought to be real and the P-400 wasn't going to work. The British also had more than enough lower altitude fighters. The P-400 wasn't even performing as promised.

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## Greg Boeser (Jul 8, 2021)

Now just think what mayhem those P-400s could have caused if they had been sent to Malaya to augment the Buffalos already there.
They've got to be better than tropicalized Hurricane Mk IIBs.

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## P-39 Expert (Jul 8, 2021)

Shortround6 said:


> A connection can be drawn between the BoB and the P-39/P-400 in that the P-39 was no longer wanted by the British not because the the BoB was already over ( and Russian being invaded when they showed up) but because the P-39 no longer met the tactical requirements of the British.
> 
> Operational altitudes had gone from 15,000-20,000 ft in the Battle of France to 25,000-30,000ft in the BoB in just 6 months.
> The British had introduced the Hurricane II with the Merlin XX and the Spitfire V with the Merlin 45 many months before the P-400 showed up.
> ...


Certainly not at 7850lbs. At 7100lbs that's a different story.


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## pbehn (Jul 8, 2021)

P-39 Expert said:


> Certainly not at 7850lbs. At 7100lbs that's a different story.


Why, you keep saying this but why? Can we have some facts about thrust, lift drag etc, not just your feelings.

Both the Spitfire and Hurricane had more wing span and wing area than the P-39


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## Peter Gunn (Jul 8, 2021)

nuuumannn said:


> Agree, man, keep your head down and your loved ones close.


I appreciate the thoughts you guys, but thankfully it was kind of a big let down, not that I'm complaining mind you. I don't think the wind hit 35MPH but the vegetation got quite a dousing.

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## Shortround6 (Jul 8, 2021)

The 7100lbs is quite a trick.
Take a P-30D-1 and take out the wing guns (95lbs) and 115lbs of armor (leaving you with the armor & BP glass of a P-39C) and you get just over 6400lbs of tactical empty aircraft.

Now we can add fuel and ammo.

120 gallons of fuel is 720lbs OOPS, we are over 7100lbs.
118 gallons of fuel? OOPS we have no ammo. 
160lbs worth of ammo (no .30 cal), we are down to 91 gallons of fuel 

Oh yeah, forgot about about the 88lbs worth of ballast weights.
No problem, just don't put in any ammo for one of the .50 cal guns and leave out another 4 1/2 gallons of fuel. 
well we can take out one 50cal since we don't have ammo for it. 
and put back in about 12 gallons of fuel.

May I present you with the
_*Superfighter P-400*_
one 20mm with 60 rounds and one .50 cal with 200 rounds.
about a gallon less fuel than a Spitfire.

Yeah, I can see the British jumping all over that one. 

Edit: If you take out one .50 cal and 200rounds of .50 cal ammo how much ballast do you have to put back in?

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## Shortround6 (Jul 8, 2021)

Peter Gunn said:


> I appreciate the thoughts you guys, but thankfully it was kind of a big let down, not that I'm complaining mind you. I don't think the wind hit 35MPH but the vegetation got quite a dousing.


Good news! you won't have to run the sprinklers for a few days.

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## wuzak (Jul 8, 2021)

Shortround6 said:


> May I present you with the
> _*Superfighter P-400*_
> one 20mm with 60 rounds and one .50 cal with 200 rounds.
> about a gallon less fuel than a Spitfire.



With IFF?

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## Shortround6 (Jul 8, 2021)

wuzak said:


> With IFF?


Yes, 
Unless some people believe that the British would have operated a fighter without IFF in the ETO in 1941/42 without IFF. 
we could lighten the plane up a bit by going back to a radio like the P-39C used, barely able to communicate from Calais to Dover on a good day. 

Those wimpy British sure ruined a good airplane, wanting cabin heat for flights over 20,000ft. A radio with more range than 10-20 miles, not wanting to get shot down by their own AA guns.

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## Just Schmidt (Jul 8, 2021)

P-39 Expert said:


> Wiki's information is from the Strategic Bombing Survey.
> 
> BoB has nothing to do with the P-39. Most all the information I quote on here is from wwiiaircraftperformance.org.
> 
> ...


I suppose you mean 
THE UNITED STATES STRATEGIC BOMBING SURVEY
Summary Report
(European War)
September 30, 1945?

at 









United States Strategic Bombing Survey: Summary Report (European War)


United States Strategic Bombing Survey: Summary Report (European War)



www.anesi.com





You didn't specify which page and section, while such blanket references are common within some disciplines, at least most historians still insist on greater precision. I did not find the numbers you referred to, however i found this:

"Conventionally the air forces designated as "the target area" a circle having a radius of 1000 feet around the aiming point of attack. While accuracy improved during the war, Survey studies show that, in the over-all, only about 20% of the bombs aimed at precision targets fell within this target area. A peak accuracy of 70% was reached for the month of February 1945." Page 5.

You will notice the expression _target area. _As for the question what was targeted, consider this:

"In the latter half of 1944, aided by new navigational techniques, the RAF *returned* with *part* of its force to an attack on *industrial targets*
. These attacks were notably successful but it is with the attacks on urban areas that the RAF is most prominently identified." Page 3, my bold. And:

"As a rule the industrial plants were located around the perimeter of German cities and characteristically these were relatively undamaged." Page 4.

I know this is not the bob, but you were the one to introduce the word never and bring the fight down to RAF night bomber levels. As to fighter bombers not fighting above 25000 feet, that is possibly correct in a restricted sense of the word. They were only being bounced by planes flying higher. Originally it was not a question of fighting at 30000 feet, it was all about making you cringe. Anyway, in your restricted meaning of fighting, the great majority of Lancasters over Germany in 1943 were not fighting, they were merely motoring quietly around and burning out the harts of Germany's cities. Even when attacked, they often preferred to decline a fight with a cork screw manouvre. By the way a hint to what was targeted when RAF shifted from their admittedly abysmal early war 'precision' night bombing to area bombing is the introduction of the term 'de-housing'.

As others have explained, die Luftwaffe in 1940 possessed excellent navigational aids, more than enough to bomb a target the size of London during night. They did not there encounter the problems that RAF did over Germany with the restricted range of such aids on account of the earths curvature. In this face of the war the poor chaps indeed struggled to find the right city or, occasionally, even country. This is one important factor in bringing averages over the entire war down.

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## buffnut453 (Jul 8, 2021)

Shortround6 said:


> The 7100lbs is quite a trick.
> Take a P-30D-1 and take out the wing guns (95lbs) and 115lbs of armor (leaving you with the armor & BP glass of a P-39C) and you get just over 6400lbs of tactical empty aircraft.
> 
> Now we can add fuel and ammo.
> ...



And we go back to the fundamental question that has yet to be answered (despite being asked many, MANY times). If simply removing the wing guns and a few other bits and bobs resulted in a significant performance improvement, why wasn't that practice implemented more commonly across the US P-39/P-400 units? There is evidence that the wing guns were removed from a limited number of aircraft. However, the reaction wasn't "Wow! Removing those guns turned a pig's ear into a silk purse!"....it was more "Meh...it improved the old dog a little bit."

Despite removing the wing guns on some P-39s, the USAF still got rid of the P-39 from combat units as quickly as they possibly could. Why would they do that if the P-39 was such a competitive aircraft in 1942?

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## Shortround6 (Jul 8, 2021)

buffnut453 said:


> Despite removing the wing guns on some P-39s, the USAF still got rid of the P-39 from combat units as quickly as they possibly could. Why would they do that if the P-39 was such a competitive aircraft in 1942?


there are several reasons (in my opinion) 
1. It wasn't competitive for much of 1942. 
The P-39M and N don't start rolling out of the factory doors until late fall/early winter of 1942. Getting them to combat theaters takes several more months. Some units were still using P-39Ds (of different varieties ) in early 1943. The P-39K & L fall somewhat in between. FIRST delivery was in July of 1942, only 460 built of both models?
There were about 1760 (?) P-39Ds, P-400s and P-39Fs (D with a different prop) built.

2. P-39s used 3 different engines (or power ratings with several different "models" having the same rating) after the P-39C. 

A. the 1150hp take off engine with the 8.80 gears. 
B. the 1325hp take off engine with the 8.80 gears. Performance above around 12,000ft is pretty much the same. late Ds, and the K & L. 
C. the 1200hp take off engine with the 9.60 gears, shows up in the M has performance improved by about 3-4000ft. 

3. The US does not _officially_ approve WEP ratings at low altitude until late 1942/ early 1943 in _any_ engine. Despite what units might do at the local level. 

testing a P-39M/N in late 1942 using WEP settings doesn't tell you what the planes in the Field were doing with their older engines and with throttle settings anywhere from standard limits to pressure readings having factory service reps 'cringing'. 

BTW most of the later Weight charts have the P-39s carrying 300rpg for the wing guns instead of 1000rpg. this would save about 180lbs by itself. or just over 1/2 the weight of the four guns and 1000rpg. If the combat units have already taking out just about 180lbs then taking out another 170-180lbs might not show that big a difference???

Basically the vast majority of the P-39s in combat service in 1942 are the planes using the 1150hp engine with somewhat scattered unofficial "boosting" And it is this performance level that established the P-39s reputation for good or bad.

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## pbehn (Jul 8, 2021)

Shortround6 said:


> A connection can be drawn between the BoB and the P-39/P-400 in that the P-39 was no longer wanted by the British not because the the BoB was already over ( and Russian being invaded when they showed up) but because the P-39 no longer met the tactical requirements of the British.
> 
> Operational altitudes had gone from 15,000-20,000 ft in the Battle of France to 25,000-30,000ft in the BoB in just 6 months.
> The British had introduced the Hurricane II with the Merlin XX and the Spitfire V with the Merlin 45 many months before the P-400 showed up.
> ...


The high altitude Wellington which led to the Merlin 60 series came from Operational Requirement OR 94 which was placed in 1940. The prototype Spitfire Mk IX first flew in Sept 1941, so it was known well before that that planes would be going to higher altitudes. However without any change in altitude the RAF were having problems with pilots blacking out at circa 30,000ft even with oxygen supplies working. Even today no one can be examined to see if they will suffer from altitude sickness and it isnt all to do with low oxygen, but also the low pressure.

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## XBe02Drvr (Jul 8, 2021)

Greg Boeser said:


> Now just think what mayhem those P-400s could have caused if they had been sent to Malaya to augment the Buffalos already there.
> They've got to be better than tropicalized Hurricane Mk IIBs.


Hayabusa fodder.

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## buffnut453 (Jul 8, 2021)

Shortround6 said:


> there are several reasons (in my opinion)
> 1. It wasn't competitive for much of 1942.
> The P-39M and N don't start rolling out of the factory doors until late fall/early winter of 1942. Getting them to combat theaters takes several more months. Some units were still using P-39Ds (of different varieties ) in early 1943. The P-39K & L fall somewhat in between. FIRST delivery was in July of 1942, only 460 built of both models?
> There were about 1760 (?) P-39Ds, P-400s and P-39Fs (D with a different prop) built.
> ...



Agreed...the first really large-scale production variants (M or N) don't appear until quite late in the game, by which time there are better options available. Funnily enough we've been saying this for dozens of pages now but it still doesn't seem to register in certain quarters.

The other interesting thing about the P-39 are ongoing changes, throught its life, to strengthen the design. These changes were sometimes in areas that hadn't really seen an increase in load. Such beefing up of the airframe would increase empty weight but, more importantly, it perhaps suggests that there were some pervasive flaws--more charitably suboptimal compromises--in the design. Examples include:

*P-39Q-15 *Reinforced inclined deck to prevent .50 in (13 mm) machine gun mounting cracking, bulkhead reinforcements to prevent rudder pedal wall cracking, a reinforced reduction gearbox bulkhead to prevent cowling former cracking.

*P-39Q-25 *Reinforced aft-fuselage and horizontal stabilizer structure.


On top of that, we also see constant flip-flopping on the amount of armour protection (this doesn't include photo recce birds which had additional armour for the oil tanks and increased belly armour protection) and reconfiguration to maintain a safe CofG:

*P-39D-BE* Production variant based on the P-39C with 245 lb (111 kg) of additional armor, self-sealing fuel tanks

*P-39N-1 *Internal changes to adjust center of gravity when nose guns were fired.

*P-59N-5 *Reduced armour to from 231lb to 193lb.

*P-39Q-1 *Armour was increased to 231 lb.

*P-39Q-5 *Reduced armour to 193lb.

*P-39Q-10 *Variant with increased armor (228 lb).


To me, this all smacks of tinkering to eke out performance from an airframe that had no growth potential. When you compare it against the Spitfire, which doubled its max all-up weight, the P-39 simply struggled to perform throughout its life in comparison to other contemporary fighters.

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## XBe02Drvr (Jul 8, 2021)

buffnut453 said:


> The other interesting thing about the P-39 are ongoing changes, throught its life, to strengthen the design. These changes were sometimes in areas that hadn't really seen an increase in load. Such beefing up of the airframe would increase empty weight but, more importantly, it perhaps suggests that there were some pervasive flaws--more charitably suboptimal compromises--in the design. Examples include:


Wasn't Bell supposedly the "expert" in lightweight fighter design? The antithesis of Grumman, as it were.

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## Shortround6 (Jul 8, 2021)

well, 





It didn't work quite as well as promised either.

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## Milosh (Jul 8, 2021)

Bell XP-77 - Wikipedia







en.wikipedia.org


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## Thumpalumpacus (Jul 8, 2021)

Shortround6 said:


> BTW most of the later Weight charts have the P-39s carrying 300rpg for the wing guns instead of 1000rpg. this would save about 180lbs by itself. or just over 1/2 the weight of the four guns and 1000rpg. If the combat units have already taking out just about 180lbs then taking out another 170-180lbs might not show that big a difference???



Maybe I'm ignorant or naive, but it seems to me that removing 70% of one's ammunition in a fighter plane is 1) a tacit admission that the plane cannot do the job as designed and 2) requires much better gunnery from the pilot in order to approach the hit-ratio of a full ammo load-out.

Is there something in the equation I'm missing here?


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## FLYBOYJ (Jul 8, 2021)

Shortround6 said:


> well,
> View attachment 631643
> 
> It didn't work quite as well as promised either.


Beat me to the punch on this as well. What I think is funny how it resembled a concept design that led to the P-39

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## GrauGeist (Jul 8, 2021)

FLYBOYJ said:


> Beat me to the punch on this as well. What I think is funny how it resembled a concept design that led to the P-39
> 
> View attachment 631646


Several of the Army's "lightweight fighter" submissions looked similar.
The Douglas XP-48 was along those lines, too (paper only, never built).

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## Shortround6 (Jul 8, 2021)

Thumpalumpacus said:


> Maybe I'm ignorant or naive, but it seems to me that removing 70% of one's ammunition in a fighter plane is 1) a tacit admission that the plane cannot do the job as designed and 2) requires much better gunnery from the pilot in order to approach the hit-ratio of a full ammo load-out.
> 
> Is there something in the equation I'm missing here?


My opinion, somebody over speced the ammunition load. At full cycle rate they had 50 (five zero) seconds of firing time for the .30 cal guns. 300 rounds gives 15 seconds. The 20mm gun had 6 seconds. The 37mm with 30 rounds had 12 seconds. The .50 cals had around 20 seconds depending on actual rate of fire. Perhaps 300 rounds may not be enough, but anything over 500 rounds was probably too much.


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## pbehn (Jul 8, 2021)

Shortround6 said:


> My opinion, somebody over speced the ammunition load. At full cycle rate they had 50 (five zero) seconds of firing time for the .30 cal guns. 300 rounds gives 15 seconds. The 20mm gun had 6 seconds. The 37mm with 30 rounds had 12 seconds. The .50 cals had around 20 seconds depending on actual rate of fire. Perhaps 300 rounds may not be enough, but anything over 500 rounds was probably too much.


Did anyone in USA do studies of what happened in the BoB? It was recommended to only fire 303s in two second bursts. 50 seconds of firing in 2 second bursts is what happens in video games.


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## GrauGeist (Jul 8, 2021)

pbehn said:


> Did anyone in USA do studies of what happened in the BoB?


It's possible - the P-47 did get eight .50MGs, which seems to me that they were pretty serious about perforating anything on the receiving end...

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## pbehn (Jul 8, 2021)

GrauGeist said:


> It's possible - the P-47 did get eight .50MGs, which seems to me that they were pretty serious about perforating anything on the receiving end...


Well the British increased from 4 to 8 mgs before the war based on how many bullets it needed to take down a bomber in the time you could expect a plane to have it in its gunsight. The P-47 has the same number but obviously more hitting power, and about the same as a Spitfire with 2 x 20mm canon and 4 x 0.303 mgs. My point was/is they didnt put 4 x 0.5" guns and more than twice the ammunition, just as when the P-51B/C changed to P-51D they didnt put more than 50% additional ammunition they put an extra gun with a similar amount of ammunition. You can always say a plane can be taken down with one bullet, but the more bullets hit the more likely you are to have success, if the time on target is short, you have to hit with more bullets. If you need to fire at things for 50 seconds, the things you are firing dont work.


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## P-39 Expert (Jul 8, 2021)

Shortround6 said:


> The 7100lbs is quite a trick.
> Take a P-30D-1 and take out the wing guns (95lbs) and 115lbs of armor (leaving you with the armor & BP glass of a P-39C) and you get just over 6400lbs of tactical empty aircraft.
> 
> Now we can add fuel and ammo.
> ...


Not much of a trick really. Figures from AHT. Would do columns, but I can't seem to make columns work.

P-400 empty 5550, 2x50cals 139, ammo 200rds/gun 129, 20mm 127, ammo 32, armor plate/glass (as P-39N w/o nose armor) 122, oxygen and gunsight 11, pilot/chute 160, fuel (120gal) 720, oil 71, total 7061. Deduct 50 from armament provisions (205 in empty weight since you don't have the 30cal wing guns) and total weight is 7011. This plane would have worked well in NG since radar wouldn't be there until fall '42 and by then newer models would be available. For service in GB add the 110lb IFF set for a total of 7121. Personally I would like a total of 120rds of 20mm ammo Like the Spitfire) so add another 32lbs. 

Go here to see what a 7075lb P-39 will do. http://www.wwiiaircraftperformance.org/P-39/P-39C_40-2988.pdf Climb would have been 3720fpm up to 12400' (critical alt. for -35 engine as in the P-39D/D-1/F/K/L). 

Noe before I get jumped for the circular argument please note that I am just responding to Shortround's post.


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## pbehn (Jul 8, 2021)

P-39 Expert said:


> Not much of a trick really. Figures from AHT. Would do columns, but I can't seem to make columns work.
> 
> P-400 empty 5550, 2x50cals 139, ammo 200rds/gun 129, 20mm 127, ammo 32, armor plate/glass (as P-39N w/o nose armor) 122, oxygen and gunsight 11, pilot/chute 160, fuel (120gal) 720, oil 71, total 7061. Deduct 50 from armament provisions (205 in empty weight since you don't have the 30cal wing guns) and total weight is 7011. This plane would have worked well in NG since radar wouldn't be there until fall '42 and by then newer models would be available. For service in GB add the 110lb IFF set for a total of 7121. Personally I would like a total of 120rds of 20mm ammo Like the Spitfire) so add another 32lbs.
> 
> ...


Do you believe that test? From sea level to rated altitude the rate of climb was the same, a completely linear plot? And at 25,000ft the RoC was almost 1,000ft min?

The time to climb to 25,000ft is exactly the same as a Spitfire I with Merlin MkIII and Rotol prop, but 1.4 mins less than a Spitfire II with Merlin XII Spitfire Mk IIA Performance Testing

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## Thumpalumpacus (Jul 8, 2021)

Shortround6 said:


> My opinion, somebody over speced the ammunition load. At full cycle rate they had 50 (five zero) seconds of firing time for the .30 cal guns. 300 rounds gives 15 seconds. The 20mm gun had 6 seconds. The 37mm with 30 rounds had 12 seconds. The .50 cals had around 20 seconds depending on actual rate of fire. Perhaps 300 rounds may not be enough, but anything over 500 rounds was probably too much.




The whole thing shows the balance between ammo carriage, gunnery, and hitting-power. Is fifteen seconds of thirty-cal sufficient for more than one target? Six seconds of 20-mm seems to make a big demand on gunnery training, too.

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## P-39 Expert (Jul 8, 2021)

pbehn said:


> Do you believe that test? From sea level to rated altitude the rate of climb was the same, a completely linear plot? And at 25,000ft the RoC was almost 1,000ft min?
> 
> The time to climb to 25,000ft is exactly the same as a Spitfire I with Merlin MkIII and Rotol prop, but 1.4 mins less than a Spitfire II with Merlin XII Spitfire Mk IIA Performance Testing


Yes, actually better than that.


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## pbehn (Jul 8, 2021)

P-39 Expert said:


> Yes, actually better than that.


But actually not, that was the issue, the P-39 as delivered was nowhere near its obviously fake test reports. If it was as good as you claim it wouldnt have had such a negative reception, and wouldnt have had you arguing for years about taking weight off. Look at the link I posted, climb is not linear, they put an average in the test report for the P-39, the same average as the Spitfire, complete horse crap, like the 400MPH top speed.


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## P-39 Expert (Jul 8, 2021)

pbehn said:


> But actually not, that was the issue, the P-39 as delivered was nowhere near its obviously fake test reports. If it was as good as you claim it wouldnt have had such a negative reception, and wouldnt have had you arguing for years about taking weight off. Look at the link I posted, climb is not linear, they put an average in the test report for the P-39, the same average as the Spitfire, complete horse crap, like the 400MPH top speed.


Fake test report? That's a Wright Field official test. Just like most of the other tests on wwiiaircraftperformance.org. That's what Wright Field did, they ran official performance tests for the AAF. Seriously?


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## buffnut453 (Jul 8, 2021)

P-39 Expert said:


> Fake test report? That's a Wright Field official test. Just like most of the other tests on wwiiaircraftperformance.org. That's what Wright Field did, they ran official performance tests for the AAF. Seriously?



You've ignored a whole host of real-world data that didn't match your world view. It's pretty rich of you to criticize anyone else for behaving in exactly the same way.


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## GrauGeist (Jul 8, 2021)

There's a reason why the Army guys in the PTO nicknamed the P-400 a "P-40 with a Zero on it's tail"...

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## FLYBOYJ (Jul 8, 2021)

P-39 Expert said:


> Noe before I get jumped for the circular argument please note that I am just responding to Shortround's post.


And note that because of some of your outrageous claims, you're an open target providing it stays somewhat civil and I commend our replying membership for showing some restraint.

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## FLYBOYJ (Jul 8, 2021)

P-39 Expert said:


> Fake test report? That's a Wright Field official test. Just like most of the other tests on wwiiaircraftperformance.org. That's what Wright Field did, they ran official performance tests for the AAF. Seriously?


But it was flown by "Joe Pilot"

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## wuzak (Jul 8, 2021)

P-39 Expert said:


> Fake test report? That's a Wright Field official test. Just like most of the other tests on wwiiaircraftperformance.org. That's what Wright Field did, they ran official performance tests for the AAF. Seriously?



Was it an actual production line example, or one specially prepared for the test?

And maybe not in the configuration that was ordered.

A few of the test reports on wwiiaircraftperformance.org start with " Report on flight tests of Bell P-39X airplane at the manufacturer's plant.". Does this mean that it was tested by the company and the report relayed to the USAAF via Wright Field? Or did Wright Field test the plane, but since it was at the manufacturer's plant it may have been souped up?


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## Shortround6 (Jul 8, 2021)

P-39 Expert said:


> Not much of a trick really. Figures from AHT. Would do columns, but I can't seem to make columns work.
> 
> P-400 empty 5550, 2x50cals 139, ammo 200rds/gun 129, 20mm 127, ammo 32, armor plate/glass (as P-39N w/o nose armor) 122, oxygen and gunsight 11, pilot/chute 160, fuel (120gal) 720, oil 71, total 7061. _Deduct 50 from armament provisions (205 in empty weight since you don't have the 30cal wing guns)_ *and total weight is 7011*. This plane would have worked well in NG since radar wouldn't be there until fall '42 and by then newer models would be available. For service in GB add the 110lb IFF set for a total of 7121. Personally I would like a total of 120rds of 20mm ammo Like the Spitfire) so add another 32lbs.
> 
> ...


You know, even in New Guinea the US pilots might have like to have a radio. Just maybe they would like to talk to the other plane or to their base? Wing waggling as a form of communication is rather over rated. 
This was the radio the US used in some of it's P-39s. 




__





File:SCR-522 Data.png - RadioNerds







radionerds.com




About 90lbs 

The weight charts in the P-39D-1/D-2 manual specify the radios by model number. 

This has been gone over in some of the previous posts. 
The IFF weighed around 45lbs How much is the actual unit and how much is in "electrical" and how much is in "furnishings" I don't know. 

I Have no idea why but in AHT the P-400 has 205lbs of "armament provisions" but a P-39D-2 with the same 20mm cannon, the same two .50 cal machine guns and the same four .30 cal wing guns has 147lbs of "armament provisions". How you came up with 50lbs of it for the wing guns I don't know. 
There are a few other spots where you seem to pick and choose your weights. 

BTW your 7011lb P-39 won't get far because you forgot to put 2 gallons of oil (15lbs) into the reduction gear box behind the prop. No, it is not included in the empty weight but it is included in the tactical empty weight in the pilots manual. 

As far a seeing what a* 7075lb* P-39 would do..........ROFLMAO.

It is a *6689lb* P-39 and it won't even make level speed without failing to meet both coolant and oil temperature requirements. 
level speed is usually much easier to cool than climbing because you have a lot more air going through the cooling system per minute. 
No surprise it fails to meet cooling requirements when climbing. This is for both oil and coolant. 
Perhaps the "D"s got better cooling? or a more positive method of controlling the exit flap/s? 

This is one reason the argument goes circular. You ignore contradictory information (like the radios) and come up with your own, most favorable numbers. The only way to come up with 11lbs for gun sight and oxygen in your example is to use the gun sight from the P-400 and the oxygen weight number from the P-39D-2. The numbers for the D-2 are only 13lbs so it makes no practical difference. But why juggle the numbers to begin with?

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## Glider (Jul 8, 2021)

I often like to stand back and take a simplistic view of things and I keep having the same thought.

If any aircraft designer, of any aircraft, military or civil, of any nation, ever, could save even 150lb in weight and improve performance. They would be doing cartwheels around the hanger, paying for all the drinks in the bar that night and no doubt get a promotion.

Yet here we have tens of thousands of engineers in the field and hundreds more in Bell who couldn't see these simple, easy, obvious changes, that would save vastly more 150lb. There's a reason for that.

Also Russia used it in the main as a low / medium level fighters where its performance was good, but not exceptional, at least when compared to a Typhoon which no one would say is the best fighter of the war.

The next observation is that everyone gets sucked into debating _X_ mph or _Y_ climb rate and everyone tends to forget the rather nasty handling problems that the P39 had.

Finally, Russia was offered what they were offered and these tended to be what was left over after the requirements of the USAAF and RAF had been met. I wouldn't mind betting that if they had been offered the P47 in the same numbers, instead of the P39 they would have dropped the P39 like a hot potato.

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## GrauGeist (Jul 8, 2021)

Glider said:


> I often like to stand back and take a simplistic view of things and I keep having the same thought.
> 
> If any aircraft designer, of any aircraft, military or civil, of any nation, ever, could save even 150lb in weight and improve performance. They would be doing cartwheels around the hanger, paying for all the drinks in the bar that night and no doubt get a promotion.
> 
> ...


While I agree with all stated here, I do have to mention that the Soviets were given 200 P-47s and they were unimpressed.
The P-47's strength lay with it's performance at medium to high altitudes where little combat took place.
They need maneuverable aircraft at low to moderate altitudes and the P-47 was not able to meet those needs.
So the ones they had were mostly used for long range recon or defense of specific areas.


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## Glider (Jul 9, 2021)

I stand corrected

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## Snautzer01 (Jul 9, 2021)

GrauGeist said:


> They need maneuverable aircraft at low to moderate altitudes and the P-47 was not able to meet those needs.


For low/middle they should have used it as a fighter bomber. Think the usaaf P-47 fighter bombers guys did all right by all accounts


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## pbehn (Jul 9, 2021)

P-39 Expert said:


> Fake test report? That's a Wright Field official test. Just like most of the other tests on wwiiaircraftperformance.org. That's what Wright Field did, they ran official performance tests for the AAF. Seriously?


Yes, the rate of climb is the same at 3 consecutive readings, so they have taken one time to climb value and put the average before that. It was probably done by a "joe pilot". Wright field is above sea level but the quote a rate of climb at sea level.


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## Juha3 (Jul 9, 2021)

P-39 Expert said:


> Not much of a trick really. Figures from AHT. Would do columns, but I can't seem to make columns work.
> 
> P-400 empty 5550, 2x50cals 139, ammo 200rds/gun 129, 20mm 127, ammo 32, armor plate/glass (as P-39N w/o nose armor) 122, oxygen and gunsight 11, pilot/chute 160, fuel (120gal) 720, oil 71, total 7061. Deduct 50 from armament provisions (205 in empty weight since you don't have the 30cal wing guns) and total weight is 7011. This plane would have worked well in NG since radar wouldn't be there until fall '42 and by then newer models would be available. For service in GB add the 110lb IFF set for a total of 7121. Personally I would like a total of 120rds of 20mm ammo Like the Spitfire) so add another 32lbs.
> 
> ...


Heh, Bell clearly thought, that the USAAF only used small, slim pilots, who did not want to wear parachute, that was late corrected in -39Q table, pilot 200 lbs incl 20 lbs for the chute, P-400, gunsight 2.3 lbs, oxygen equip. 30.0, for P-39D 4.4 and 8.2 lbs. There is also for P-400 109.9 lb for radio.

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## P-39 Expert (Jul 9, 2021)

wuzak said:


> Was it an actual production line example, or one specially prepared for the test?
> 
> And maybe not in the configuration that was ordered.
> 
> A few of the test reports on wwiiaircraftperformance.org start with " Report on flight tests of Bell P-39X airplane at the manufacturer's plant.". Does this mean that it was tested by the company and the report relayed to the USAAF via Wright Field? Or did Wright Field test the plane, but since it was at the manufacturer's plant it may have been souped up?


Production line example.

There were only 20 -C models produced.

Wright Field test personnel, tested at the manufacturer's plant to facilitate service/repair.


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## Milosh (Jul 9, 2021)

http://www.wwiiaircraftperformance.org/P-39/P-39C_Chart-Bell_Aircraft-1400.jpg


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## pbehn (Jul 9, 2021)

The issue with the P-400 is that it didnt go anywhere near 400 so questioning test data on this aircraft has been done from the start. If it could climb to 25,000ft in exactly the same time as a Spitfire Mk I it wouldnt have been the disappointment that it actually was.


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## Milosh (Jul 9, 2021)

Yes it is from Wiki.

For the P-400

British expectations had been set by performance figures established by the unarmed and unarmored XP-39 prototype. The British production contract stated that a maximum speed of 394 mph (634 km/h) +/- 4% was required at rated altitude.[41]​ In acceptance testing, actual production aircraft were found to be capable of only 371 mph (597 km/h) at 14,090 ft (4,290 m). To enable the aircraft to make the guarantee speed, a variety of drag-reduction modifications were developed by Bell. The areas of the elevator and rudder were reduced by 14.2% and 25.2% respectively. Modified fillets were installed in the tail area. The canopy glass was faired to its frame with putty. The gun access doors on the wing had been seen to bulge in flight, so they were replaced with thicker aluminum sheet. Similarly, the landing gear doors deflected open by as much as two inches at maximum speed, so a stronger linkage was installed to hold them flush. The cooling air exit from the oil and coolant radiators was reduced in area to match the exit velocity to the local flow. New engine exhaust stacks, deflected to match the local flow and with nozzles to increase thrust augmentation, were installed. The machine gun ports were faired over, the antenna mast was removed, a single-piece engine cowling was installed and an exhaust stack fairing was added.

The airframe was painted with 20 coats of primer, with extensive sanding between coats. Standard camouflage was applied and sanded to remove the edges between the colors. Additionally, about 200 lb (91 kg) of weight was removed, making it lighter than normal (7,466 lb (3,387 kg) gross).[42]​ After these modifications, the second production aircraft (serial _AH 571_) reached a speed of 391 mph (629 km/h) at 14,400 ft (4,400 m) in flight test. As this speed was within 1% of the guarantee, the aircraft was declared to have satisfied contractual obligations.[41]​ Despite the success of these modifications, none were applied to other production P-39s. Later testing of a standard production P-400 by the British Aeroplane and Armament Experimental Establishment (A&AEE) revealed a top speed of only 359 mph (578 km/h).









Bell P-39 Airacobra - Wikipedia







en.wikipedia.org

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## P-39 Expert (Jul 9, 2021)

Shortround6 said:


> You know, even in New Guinea the US pilots might have like to have a radio. Just maybe they would like to talk to the other plane or to their base? Wing waggling as a form of communication is rather over rated.
> This was the radio the US used in some of it's P-39s.
> 
> 
> ...


Yes, all this has been discussed many times. But this is the P-39 thread where we're allowed to discuss the P-39, right?

Radio (voice) included in empty weight. 35lbs.

IFF listed in AHT as 110lbs for the P-400. If it only weighed 45lbs then the P-400 would be lighter by 65lbs, right?

"Armament Provisions" weights are different for different models. I take this to mean gun mounts, chargers, heaters, ammunition boxes etc. 50lbs is my estimate based on percentage weight of the 30cals to total weight of the guns. 

Reduction gear oil is included in total weight of oil 71lbs.

As we have discussed many times before, the 6689lb weight is the average weight of this plane during a flight due to fuel burn. Most all of the Wright Field tests for all the WW2 AAF fighters listed a weight that was less than the published gross weight from the Weight and balance Chart in the pilot's manual. British used 95% of gross weight as test weight. 6689lbs + 64gal = 7075lbs. 6689lbs divided by 95% = 7041lbs, within 34lbs of published gross weight.

Regarding engine cooling, most of the early AAF models (P-38F/G, P-47D, P-51A/B) didn't meet cooling requirements as noted in the Wright Field tests either, just like the P-39. This was common until development of automatic cooling flaps in 1944. P-39 never got these.

Yes I used the oxygen weight from the D model which saved 22lbs. P-400s at Guadalcanal had oxygen system not compatible to Marine system, so I used the AAF system. All other weights are for the P-400.

This 7100lb P-400 (or P-39) was an armored warplane with self sealing fuel tanks and cannon/heavy machine gun centerline armament.

Climb and ceiling from the tests would have been further improved in mid-42 when the 5 minute limit (3000rpm combat power) was increased to 15min. Engine power was reduced to 2600rpm (normal power) after 5min at 16750'. I estimate climb would have improved to approximately 2600fpm at 20000' and ceiling to approximately 37000' at full 3000rpm. Compare this to the 1942 A6M2 which climbed at 1800fpm at 20000' or the not yet available F4U, F6F, P-38F, or P-47D which climbed at around 2000fpm at 20000'. The 1943 FW190 also climbed at about 2000fpm at 20000'. Remember this test was in mid 1941 with the early 1150hp -35 engine. By fall of 1942 the uprated -85 engine was available for the M/N/Q models and no weight reduction was needed, although deleting the 30cal wing guns would have been nice. 

I've posted all this many times before and it is all based on factual information. The 1942 P-39s were grossly overweight for their engine power. Eliminating the 30cal wing guns and a piece of redundant armor plate would have improved performance tremendously and could have been done at forward bases.


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## buffnut453 (Jul 9, 2021)

P-39 Expert said:


> Eliminating the 30cal wing guns and a piece of redundant armor plate would have improved performance tremendously and could have been done at forward bases.



And the guns were removed for some airframes but the performance increase wasn't "tremendous". If the performance improvement had been "tremendous" then surely it would have been implemented on all P-39s in combat theatres, with requirements passed to the manufacturer to stop building airframes with wing guns?

Also, if a "tremendous" performance increase was so readily available, why did the AAF get rid of the P-39 as quickly as it did?


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## Milosh (Jul 9, 2021)

Note the use of steel.


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## pbehn (Jul 9, 2021)

P-39 Expert said:


> Yes, all this has been discussed many times. But this is the P-39 thread where we're allowed to discuss the P-39, right?
> 
> Radio (voice) included in empty weight. 35lbs.
> 
> ...


You have posted this many times as you have posted it all many times, and many times you have been told you are wrong. Was the Mustang MkI and P-51A lighter than a P-39? 50% of a P51A fuel load is almost the same as 100% of a P-39s. Did the British take Mgs off the Mustang Mk I or swap them for 4 cannon? When the P-51B was being designed they added even more fuel added more oil and probably added oxygen, plus later gyro stabilised gunsights etc etc etc. 

The 1942 P-39 was just obsolete for use in the ETO, the Mustang MkI wasnt, using the same engine and it almost always carried a camera and obviously had IFF.

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## buffnut453 (Jul 9, 2021)

Milosh said:


> http://www.wwiiaircraftperformance.org/P-39/P-39C_Chart-Bell_Aircraft-1400.jpg



That's an interesting graph...but I have huge questions over its accuracy. It claims that the P-39C had a ceiling of approx 37,500 ft and can reach 30,000ft in less than 12 minutes. However, the tabular data on this page (P-39 Performance Tests) lists the absolute ceiling for the P-39C as 34,150ft and time to 30K in 18.4 mins. These figures seem much more realistic than the chart MIlosh posted...but why the discrepancy since both were apparently created by Wright Field test pilots? 

The performance characteristics for the P-39D-1 listed in this table:



http://www.wwiiaircraftperformance.org/P-39/P-39_Aircraft_Performance_Characteristics.jpg



The P-39D-1 can't reach 31,000ft as a service ceiling and takes 25.7 minutes to get there. Even the later N and Q models take more than 25 mins to reach service ceiling.


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## wuzak (Jul 9, 2021)

P-39 Expert said:


> IFF listed in AHT as 110lbs for the P-400.



Pretty sure AHT does not list the IFF, specifically, at 110 pounds. Rather some communication systems.

Unfortunately my copy is not available to me at this time.


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## Milosh (Jul 9, 2021)

Can't answer but the graph is from the test,

WAR DEPARTMENT

AIR CORPS, MATERIEL DIVISION

Wright Field, Dayton, Ohio

_July 17, 1941_

MEMORANDUM REPORT ON
Pursuit Single Engine P-39C, A.C. No. 40-2988


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## Peter Gunn (Jul 9, 2021)

So...

Earlier, SR6 mentioned that the P-39 originally had 1,000 rpg for the .30 cals giving fifty (50) seconds of firing time.

Which got me thinking, if facing down the light, rather flammable IJA/IJN fighters and bombers, what if you ditched the entire nose armament and kept only the 4 .30's in the wings with a hefty amount of incendiary/tracers laced into those 1,000 rounds per gun?

Granted the .30 wasn't a giant killer but against the right targets that tended to flame easily and with almost a minute of firing time perhaps worth a try? If I'm full of it let me know, it just seems like a mod that would work in a specific area (SWPA) vs. a specific enemy (IJA & IJN).

Of course as I write this I realize the removal of all that weight in the nose is going to be problematic at best. Replace with ballast? And if so, you've gained nothing in weight reduction so maybe I just killed a lot of electrons for nothing with this post.

Be easy on me with critique, I'm very sensitive...


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## Peter Gunn (Jul 9, 2021)

buffnut453 said:


> That's an interesting graph...*but I have huge questions over its accuracy*. It claims that the P-39C had a ceiling of approx 37,500 ft and can reach 30,000ft in less than 12 minutes. However, the tabular data on this page (P-39 Performance Tests) lists the absolute ceiling for the P-39C as 34,150ft and time to 30K in 18.4 mins. These figures seem much more realistic than the chart MIlosh posted...but why the discrepancy since both were apparently created by Wright Field test pilots?
> 
> The performance characteristics for the P-39D-1 listed in this table:
> 
> ...


Bolded by me.

In response to the bold text, I see this at the top of the chart:






So was that a USAAF test or a Bell corporate test?


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## Shortround6 (Jul 9, 2021)

P-39 Expert said:


> Radio (voice) included in empty weight. 35lbs.
> 
> IFF listed in AHT as 110lbs for the P-400. If it only weighed 45lbs then the P-400 would be lighter by 65lbs, right?


AHT says in the table.
"Misc. equip (radio)"
If it says IFF somewhere else please point it out.
The radio was included in the empty weight of the P-39C as per the Manual. 
It was NOT included in the empty weight of the P-39D-1 and P-39D-2 as per the manual. 
By the time you get to the P-39N the radio*s* (included is the IFF) are back to being in the empty weight. They are the same radios as used in the P-39Ds. They are listed by type/model number. This probably one of the reasons the P-39N was about 100lbs heavier empty than the P-39D? 

Make sure you are comparing like to like. 


P-39 Expert said:


> "Armament Provisions" weights are different for different models. I take this to mean gun mounts, chargers, heaters, ammunition boxes etc. 50lbs is my estimate based on percentage weight of the 30cals to total weight of the guns.


So you used a WAG to come up with your number. 
You could have just used the armament provision number for the P-39D-2


P-39 Expert said:


> As we have discussed many times before, the 6689lb weight is the average weight of this plane during a flight due to fuel burn. Most all of the Wright Field tests for all the WW2 AAF fighters listed a weight that was less than the published gross weight from the Weight and balance Chart in the pilot's manual. British used 95% of gross weight as test weight. 6689lbs + 64gal = 7075lbs. 6689lbs divided by 95% = 7041lbs, within 34lbs of published gross weight.


Funny thing about that. 
In the Manual for the P-39C the performance number page (page 22) says the level speeds were with a design gross weight of 662lbs. an obvious typo.
The climb data (IAS as various altitudes, no climb rate given) was for a design gross weight of 6662lbs. 
The landing and take-off distances are given for a design weight of 6662lbs.
the weight chart comes up with a weight of 6684lbs with 104 gallons of fuel. There are no self sealing tank liners or tanks. full fuel is 170 gallons. 
Things change with time. This was common practice in the late 30s or 1940 (?)
The P-36 and early P-40 performance specifications also use a limited fuel load. The performance numbers are done with 105 gallons in the case of the P-36 with a 57 gallon overload tank available 
see http://www.wwiiaircraftperformance.org/P-36/P-36_Operation_and_Flight_Instruction.pdf
The P-40 numbers are really strange. 
see; http://www.wwiiaircraftperformance.org/P-40/P-40_Official_Summary_of_Characteristics.pdf
normal fuel is 120 gallons, max is 181 gallons. 
Performance numbers are for 120 gallons. at a design weight of 6787lbs

So, in this case the P-39C was tested at about 27lbs over it's "design" gross weight. Which is close enough, maybe they couldn't find a test pilot that weighed 160lbs in flight suit and with parachute. 


P-39 Expert said:


> Reduction gear oil is included in total weight of oil 71lbs.


If it is you are going to run out of oil before you run out of gas. P-39N carried 62lbs of oil including the gear box oil for it's 87 gallons of fuel. The P-39Ds carried 88lbs of oil including the gear box oil, Both could and did carry more oil when the drop tank was fitted. The P-39C carried 7.4 gallons in the main tank/engine (55lbs) with 15lbs for the gear box on a separate line. The tank could hold 12.1 gallons. Again the "normal" fuel load for the P-39C was 104 gallons. 
Perhaps planes in combat zones carried an extra gallon or two just for "insurance"?  
I know I would try to, especially if the engine was somewhat worn. 



P-39 Expert said:


> Regarding engine cooling, most of the early AAF models (P-38F/G, P-47D, P-51A/B) didn't meet cooling requirements as noted in the Wright Field tests either, just like the P-39. This was common until development of automatic cooling flaps in 1944. P-39 never got these.


Apparently the P-39C had semi automatic cooling flaps. At high speed the airflow pushed them shut. 
There is also a difference between a plane that has trouble cooling in a long hard climb and one that overheats in high speed level flight.

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## buffnut453 (Jul 9, 2021)

Peter Gunn said:


> Bolded by me.
> 
> In response to the bold text, I see this at the top of the chart:
> 
> ...



Great question...and I know where I'd wager my money.

The climb rate data in that graph are also hugely optimistic. Again, for comparison purposes (altitude: graph climb rate (normal power)/tabular climb rate)

Sea Level: 4200/3720
5000': 4100/3720
10,000': 3975/3720
13,050': 3850/3040
16,750': 3550/2360
20,000': 2200/1350
25,000': 1600/975
30,000': 1050/440

If we look at the military power climb rates above 20,000' then the figures are even higher in the graph:

25,000': 2200 fpm
30,000': 1550 fpm

The graph even claims a climb rate of 400fpm (normal)/750fpm (military) at 35,000'. 

These figures are simply fantastical. There is no way any P-39 ever reached these levels of performance. The must be from estimated data or must include some other factor that wasn't present in production airframes.

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## buffnut453 (Jul 9, 2021)

Peter Gunn said:


> Bolded by me.
> 
> In response to the bold text, I see this at the top of the chart:
> 
> ...



Also check out the date - created 10/29/39 and checked 2/7/40. The P-39C first flew in January 1941. The graph is entirely estimated data and of no relevance to the real airframe as delivered.

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## Shortround6 (Jul 9, 2021)

Peter Gunn said:


> Bolded by me.
> 
> In response to the bold text, I see this at the top of the chart:
> 
> ...


Look at the dates in upper left corner. 
10/29/39
and checked 2/10/40
The first YP_39 didn't fly until 9/13/40 
7 months after the chart was "checked"
the first P-39C didn't fly until Jan 1941. 11 months after the chart was "checked" 

The whole thing is calculated estimates. 

Buffnut beat me to it.

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## buffnut453 (Jul 9, 2021)

Shortround6 said:


> Buffnut beat me to it.



That's unusual!

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## Shortround6 (Jul 9, 2021)

This is what Bell was selling to the French and British. 

Note that this was page 31 of a report. 

_Maybe _the French (and later the British) thought that they could add some weight and still have a good performing plane??? 

Also please note the engine in the chart was supposed to give 1150hp from sea level to 15,000ft. 
A fantasy engine for the Aircobra until late 1942.

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## SaparotRob (Jul 9, 2021)

My Lord, he's turned you all into P-39 experts.

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## Shortround6 (Jul 9, 2021)

Expert 
/ˈekˌspərt/

noun
Person from out of town with a brief case

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## Peter Gunn (Jul 9, 2021)

SaparotRob said:


> My Lord, he's turned you all into P-39 experts.


Well, everyone has a talent for SOMETHING.

The exception is we're realistic "experts" who rely on pesky things like "data" and "facts".

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## buffnut453 (Jul 9, 2021)

Shortround6 said:


> Expert
> /ˈekˌspərt/
> 
> noun
> Person from out of town with a brief case



Ex-spurt....Ex as in has-been, spurt as in drip under pressure


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## buffnut453 (Jul 9, 2021)

So we have the lightweight, non-combat capable P-39C that, in early 1941, can reach 30,000ft in 18.4 mins and has an absolute ceiling of 34,150ft.

For comparison, here's a Spitfire MkI trial from 19 March 1940 showing performance with a constant speed Rotol propellor (source: Spitfire Mk I Performance Testing)



Height
ft.​T.A.S.
m.p.h.​Time
From
Start
Min.​Rate
of
Climb
Ft./Min.​2,000​​.7​2,820​5,000​​1.8​2,850​10,000​320​3.5​2,895​11,000​​3.9​2,905​15,000​339​5.4​2,430​18,900​354​​​20,000​353.5​7.7​1,840​25,000​345​11.0​1,250​30,000​319​16.4​660​

Service ceiling = 34,700 ft.

And we're supposed to believe that taking some guns and 100lb out of the P-400 or P-39D is going to "improve performance tremendously" when the lightweight P-39C was bested by an aircraft that was operational a year before it? 


And, just for grins, here's the same table for the Spit MkII (Source: Spitfire Mk IIA Performance Testing):


Height
Feet​Top
Speed
M.P.H.​Time
To
Climb
Mins.​Rate
of
Climb
Ft./Min.​S.L.​290​-​.​2,000​294​0.7​2925​5,000​306​1.7​2955​10,000​326​3.4​2995​15,000​345​5.0​2770​20,000​351​7.0​2175​25,000​338​9.6​1600​30,000​321​13.7​995​
Service Ceiling: 37,000ft

The MkII entered service in June 1940 and was considered operational in August of that year.

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## pbehn (Jul 9, 2021)

buffnut453 said:


> That's unusual!


I just called it a faked test report and someone got upset. 3 consecutive figures of 3,720 for rate of climb exactly the same mean thrust, lift drag remained almost the same from SL to 10,000ft the difference exactly compensated for the loss of fuel and oil burned. Or it was faked. estimated or averaged out.


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## pbehn (Jul 9, 2021)

buffnut453 said:


> So we have the lightweight, non-combat capable P-39C that, in early 1941, can reach 30,000ft in 18.4 mins and has an absolute ceiling of 34,150ft.
> 
> For comparison, here's a Spitfire MkI trial from 19 March 1940 showing performance with a constant speed Rotol propellor (source: Spitfire Mk I Performance Testing)
> 
> ...


The Spitfire I has exactly the same time to climb as that stated for the P-39C to 25,000ft, despite the Spit. being considerably lighter, with more wing span and wing area. It isnt impossible but needs special aerodynamics to produce more lift with less drag.


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## FLYBOYJ (Jul 9, 2021)

Milosh said:


> Note the use of steel.
> View attachment 631725


I think you'll find that steel was used in many high stressed areas on several combat aircraft of the period. In later years 7075 forgings or titanium would be used in these applications but you still might find steel depending on the type of aircraft and manufacturer.

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## pbehn (Jul 9, 2021)

FLYBOYJ said:


> I think you'll find that steel was used in many high stressed areas on several combat aircraft of the period. In later years 7075 forgings or titanium would be used in these applications but you still might find steel depending on the type of aircraft and manufacturer.


The Spitfire always had steel wing spars and was always a light design, the Blenheim used steel box work in its structure and was always a deceptively heavy light bomber. Ingenuity counted for a lot at the time.

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## GrauGeist (Jul 9, 2021)

The Me262 used steel skin instead of aluminum due to a shortage of the latter.


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## P-39 Expert (Jul 9, 2021)

buffnut453 said:


> That's an interesting graph...but I have huge questions over its accuracy. It claims that the P-39C had a ceiling of approx 37,500 ft and can reach 30,000ft in less than 12 minutes. However, the tabular data on this page (P-39 Performance Tests) lists the absolute ceiling for the P-39C as 34,150ft and time to 30K in 18.4 mins. These figures seem much more realistic than the chart MIlosh posted...but why the discrepancy since both were apparently created by Wright Field test pilots?
> 
> The performance characteristics for the P-39D-1 listed in this table:
> 
> ...


This graph is a projection, not actual. Dates on graph predate production. I'm referring to the July 1941 P-39C Wright Field test.


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## P-39 Expert (Jul 9, 2021)

Shortround6 said:


> AHT says in the table.
> "Misc. equip (radio)"
> If it says IFF somewhere else please point it out.
> The radio was included in the empty weight of the P-39C as per the Manual.
> ...


Radio: AHT listed the voice radio in empty weight, IFF radio as part of load. What else would it be?

Yes WAG for 30cal portion of "Armament Provisions". Please provide a more accurate WAG.

Average American man in the Army in WWII was 5'8" and weighed 140lbs. Fast food hadn't been invented yet.

What is your point about the amount of oil? 

No auto cooling flaps. Spring loaded, airstream pushed them back partly closed. 

Are you saying that the P-400 weights I furnished are not correct?


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## pbehn (Jul 9, 2021)

P-39 Expert said:


> Radio: AHT listed the voice radio in empty weight, IFF radio as part of load. What else would it be?
> 
> Yes WAG for 30cal portion of "Armament Provisions". Please provide a more accurate WAG.
> 
> ...


What is your point about all this? Arguing about the weight of every component, presenting and representing discredited tests. It has been going round and around for years.


Even the name P-400 is a laugh, why not the P-350? You cannot make a case for the P-39 being a good aircraft ever.

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## 33k in the air (Jul 9, 2021)

pbehn said:


> What is your point about all this?



That the P-39 was the F-22 of its day? Something like that, it seems.


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## FLYBOYJ (Jul 9, 2021)

P-39 Expert said:


> Average American man in the Army in WWII was 5'8" and weighed 140lbs. Fast food hadn't been invented yet.


With clothing and gear W&B in the Form 1 was calculated at either 180 or 200 pounds

















drgondog Any comments?

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## pbehn (Jul 9, 2021)

33k in the air said:


> That the P-39 was the F-22 of its day? Something like that, it seems.


It would have been if gravity and the British hadnt got involved in an unholy conspiracy. 

Even the stuff about radios I dont get, the British had been using radios in planes since around 1930, I cant believe the USA was any different because pictures of the Boeing P-26 have aerials on and the Gloster Gladiator had them. At the time a better radio wouldnt be lighter, it would be about the same as others but with more range and channels. I really dont get the point at all. This is a good read into the radio side of aviation warfare SpitfireSpares.com - warbird Instruments

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## Shortround6 (Jul 9, 2021)

P-39 Expert said:


> Radio: AHT listed the voice radio in empty weight, IFF radio as part of load. What else would it be?


Where in AHT does it say that? 

The manuals for the later P-39s have the radios in the empty weight. But the manual for the D-1 and D-2 definitely have them in the basic load section. 
Weight and balance chart may list things differently than a construction specification chart. 
P-39K has a 


P-39 Expert said:


> Average American man in the Army in WWII was 5'8" and weighed 140lbs. Fast food hadn't been invented yet.


Great, naked pilot with 20lb parachute. 
By the P-39K & L manuals the pilot & parachute allowance was 200lbs. 
I guess fast food was not only invented but widely distributed on/near AAC bases by the end of 1942? 


P-39 Expert said:


> What is your point in British about the amount of oil?


Point is you have to use the right weight for the mission, not the weight that looks the best. 
P-39K & L used 71lbs total but then they are listed as using 104 gallons fuel as normal load with 16 gallons as internal overload. 

You may need another 8lbs of oil if you fill the fuel tanks to 120 gallons. 

You are the one saying the P-39 could have been used for escort missions, not without more oil and weight. 

You may want to find some other aircraft that changed weights by 300-500lbs and see what kind of difference it made.
P-40 Kittyhawk in British test showed a 110fpm loss in climb with the 52 US gallon drop tank fitted. Granted the Kitty hawk was not very good climbing to begin with but a change of 360lbs didn't do much either for or against the plane. 
Spitfire V with four 20mm cannon and a nearly 400lb weight gain over a standard Vb lost 350fpm in climb and took an extra 1 minute even (0 seconds) to reach 20,000ft. It was actually 3mph faster.

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## pbehn (Jul 9, 2021)

FLYBOYJ said:


> With clothing and gear W&B in the Form 1 was calculated at either 180 or 200 pounds
> 
> View attachment 631745
> 
> ...


Couldn't ball turret gunners be re trained to fly P-39s? I am trying to think outside the box.

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## Thumpalumpacus (Jul 9, 2021)

Radios? Who needs radios?

IFF? Who needs that?

Guns? Who needs more than three?

Range? I've got a range in my kitchen, dammit. I don't need another range.

Gotta like 

 P-39 Expert
, he'll break out a Ditchwitch digging a hole in defense of his favorite airplane. Shame he can't really put things into perspective, but hey, there's a lot like him: far too invested emotionally to think rationally at all.

It's only a matter of time before he figures out how to hang a Genie on a 'Cobra and be shooting down Tu-95s well into the 60s.

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## buffnut453 (Jul 9, 2021)

pbehn said:


> Even the stuff about radios I dont get, the British had been using radios in planes since around 1930.



Actually since 1918. There was operational use of radios for air-to-ground communication in 1918 by 11 Sqn RAF.

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## pbehn (Jul 9, 2021)

buffnut453 said:


> Actually since 1918. There was operational use of radios for air-to-ground communication in 1918 by 11 Sqn RAF.


I didnt know when they switched from Morse to voice.


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## Shortround6 (Jul 9, 2021)

They tried carrier pigeons but they kept getting hit by the tail surfaces when released.


My coat is nearby.

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## pbehn (Jul 9, 2021)

Shortround6 said:


> They tried carrier pigeons but they kept getting hit by the tail surfaces when released.
> 
> 
> My coat is nearby.


You jest? Bomber command aircraft carried pigeons throughout most of the war (until 1943) Carrier Pigeons in the Bomber War

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## SaparotRob (Jul 9, 2021)

Could shifting the IFF into the pilot's seat correct the balance issues?


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## pbehn (Jul 9, 2021)

SaparotRob said:


> Could shifting the IFF into the pilot's seat correct the balance issues?


Why not take the wings off and mount the P-39 behind the pilot of a P-47? We need novel solutions to this impasse?

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## SaparotRob (Jul 9, 2021)

pbehn said:


> Why not take the wings off and mount the P-39 behind the pilot of a P-47? We need novel solutions to this impasse?


Brilliant!


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## pbehn (Jul 9, 2021)

SaparotRob said:


> Brilliant!


We need to get a solution, this has been going on almost as long as the USA was at war. By 1942 the P-47 was being introduced, whether it had 8 x 0,5mgs 12 of the same or non at all would make very little difference to its tested performance. All fighters got heavier for all sorts of reasons. The Spitfire doubled in weight during the war but was still light compared to a P-51 or P-47, yet still we are discussing the weight of a pilot and an IFFing radio on the P-39. Everything is a trade off and weight didnt matter if it could be coped with and justified. The British used two planes with the Allison engine the P-40 and P-51(as Mustangs and P-51s), both were heavier than the P-39, which they didnt use, because it was rubbish. Much of the discussion is trending to a Reno race with a stipulation that the pilot has a Colt 45 to qualify in the "military" category. An aeroplane with no radio, no armour, and no guns with a crap engine isnt a military machine.

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## Greg Boeser (Jul 9, 2021)

Well, on paper, the P-39 is faster, has a better climb rate, and a heavier offensive battery than a P-40. 
But, the P-40 rolled better, held a turn better, and could take more punishment. Plus it could carry more external armament. And had better range. And was easier to service. There is a reason that P-39 equipped units in the field clamored for better aircraft. By the time better P-39s became available, P38s, P-47s, and P-51s were being produced in quantity. As to the USSR, the P-39 was the best on hand when it was introduced there. It was faster and more maneuverable, and had better pilot visibility, radios, etc., than the early LaGGs, MiGs, and even Yaks, and head and shoulders above the I-153s and I-16s the Russian pilots had been flying.

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## GrauGeist (Jul 9, 2021)

P-39 Expert said:


> Average American man in the Army in WWII was 5'8" and weighed 140lbs. Fast food hadn't been invented yet.


The average American GI was much heavier than that.

Also, remember the cartoons where the some poor bastard was peeling a pile of potatoes?
Yeah...that was real.

C-Rations contained:
Meat stew with vegetables
Meat stew with beans
Meat stew with vegetables hash
Spaghetti in meat sauce
Pork and beans
Chopped ham, eggs and potatoes
Franks and beans
Meat and noodles
Pork and rice
Chicken and vegetables
Ham and Lima beans

Plus the K and D rations were aimed toward high calorie intake.

And these were just field issue, the mess menu was also geared for high caloric intake.

If a GI weighed 140 pounds, he was either suffering from dysentary or was a POW.

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## ThomasP (Jul 10, 2021)

re height and weight of US soldiers in WWII, skivies only

The average height/weight of the US soldier in 1918 was 5' 7.5" / 154 lbs
The average height/weight of the US recruit in 1943 was 5' 8.1" / 152 lbs


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## GrauGeist (Jul 10, 2021)

ThomasP said:


> re height and weight of US soldiers in WWII, skivies only
> 
> The average height/weight of the average US soldier in 1918 was 6'7.5"/154 lbs
> The average height/weight of the average US recruit in 1943 was 6'8.1"/152 lbs


The US was still locked in a depression and the majority of recruits were going to eat better than they did in civilian life.

Many of the recruits were depression orphans seeking a way out, too.


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## Greg Boeser (Jul 10, 2021)

Umm. Did you mean to express those heights in inches, because it looks like you threw in an apostrophe, which makes the average height taller than current professional basketball rosters.


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## ThomasP (Jul 10, 2021)

Oops!
Thanks Greg Boeser. You are correct, I meant to change the inches to feet (') and inches ("). I have corrected my post.

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## wuzak (Jul 10, 2021)

P-39 Expert said:


> Regarding engine cooling, most of the early AAF models (P-38F/G, P-47D, P-51A/B) didn't meet cooling requirements as noted in the Wright Field tests either, just like the P-39. This was common until development of automatic cooling flaps in 1944. P-39 never got these.





Shortround6 said:


> Apparently the P-39C had semi automatic cooling flaps. At high speed the airflow pushed them shut.
> There is also a difference between a plane that has trouble cooling in a long hard climb and one that overheats in high speed level flight.





P-39 Expert said:


> No auto cooling flaps. Spring loaded, airstream pushed them back partly closed.



Whose fault was it that the P-39 didn't get automatic cooling flaps?

And are you certain that the automatic cooling flaps weren't incorporated until 1944? Surely they were in use before then, particularly in aircraft with air cooled engines?


btw, the Spitfire had 2 position cooling flaps for much, if not all, of its service life. The Spitfire III was to have a much improved radiator system, but that was never adopted for production aircraft, due to production being given priority.


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## pbehn (Jul 10, 2021)

Greg Boeser said:


> Well, on paper, the P-39 is faster, has a better climb rate, and a heavier offensive battery than a P-40.
> But, the P-40 rolled better, held a turn better, and could take more punishment. Plus it could carry more external armament. And had better range. And was easier to service. There is a reason that P-39 equipped units in the field clamored for better aircraft. By the time better P-39s became available, P38s, P-47s, and P-51s were being produced in quantity. As to the USSR, the P-39 was the best on hand when it was introduced there. It was faster and more maneuverable, and had better pilot visibility, radios, etc., than the early LaGGs, MiGs, and even Yaks, and head and shoulders above the I-153s and I-16s the Russian pilots had been flying.


Most important, the P-40 was already in service with few problems with the RAF in N Africa before a P-39 was unpacked in UK, by the time the P-39 was sorted the P-40 was also sorted and being used increasingly as a fighter bomber.


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## Just Schmidt (Jul 10, 2021)

ThomasP said:


> re height and weight of US soldiers in WWII, skivies only
> 
> The average height/weight of the US soldier in 1918 was 5' 7.5" / 154 lbs
> The average height/weight of the US recruit in 1943 was 5' 8.1" / 152 lbs


As one who stands about two turds and a half above ground fully stretched, I strongly protest against this recent fixation on height, first disguised as ceiling of aircraft but now blatantly heightist and clearly demeaning of us who are vertically challenged.

Anybody sharing in my experience of being relegated a status as below average, is recommended to join us in the movement for equal heights.

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## pbehn (Jul 10, 2021)

Just Schmidt said:


> As one who stands about two turds and a half above ground fully stretched, I strongly protest against this recent fixation on height, first disguised as ceiling of aircraft but now blatantly heightist and clearly demeaning of us who are vertically challenged.
> 
> Anybody sharing in my experience of being relegated a status as below average, is recommended to join us in the movement for equal heights.


In my working life there were more jobs that required small people than tall ones. Eric Brown thought that he survived the Dh 108 going into rapid oscillation because he was small, it broke Geoffrey de Havilland's neck doing the same.

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## rochie (Jul 10, 2021)

Just Schmidt said:


> As one who stands about two turds and a half above ground fully stretched, I strongly protest against this recent fixation on height, first disguised as ceiling of aircraft but now blatantly heightist and clearly demeaning of us who are vertically challenged.
> 
> Anybody sharing in my experience of being relegated a status as below average, is recommended to join us in the movement for equal heights.


here, here !

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## special ed (Jul 10, 2021)

June 1959 I entered the USAF weighing 145 pounds and standing 5 feet 11 inches. I'm now 218 Pounds and 5 feet 9 1/2 inches. My, how I've grown. My long time best friend and fellow aviation nut, last weighed close to 250 pounds and stood 5 feet 6 or 7 inches and was once not hired for a freight flying job because the manager said they could haul more freight with a lighter pilot. I told him he should have said to consider him as 6 foot 3.

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## P-39 Expert (Jul 10, 2021)

pbehn said:


> We need to get a solution, this has been going on almost as long as the USA was at war. By 1942 the P-47 was being introduced, whether it had 8 x 0,5mgs 12 of the same or non at all would make very little difference to its tested performance. All fighters got heavier for all sorts of reasons. The Spitfire doubled in weight during the war but was still light compared to a P-51 or P-47, yet still we are discussing the weight of a pilot and an IFFing radio on the P-39. Everything is a trade off and weight didnt matter if it could be coped with and justified. The British used two planes with the Allison engine the P-40 and P-51(as Mustangs and P-51s), both were heavier than the P-39, which they didnt use, because it was rubbish. Much of the discussion is trending to a Reno race with a stipulation that the pilot has a Colt 45 to qualify in the "military" category. An aeroplane with no radio, no armour, and no guns with a crap engine isnt a military machine.


P-47 didn't see combat until April 1943. I doubt the Spitfire doubled in weight but horsepower roughly doubled also. Weight did matter when the engine only developed 1150hp. Tell the Soviets that the P-39 was rubbish. And it had a radio, and armor plate/glass, and large caliber guns, and the engine wasn't crap. It was definitely a military machine. As long as you keep saying obviously false statements like this I will keep disagreeing with you.

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## pbehn (Jul 10, 2021)

P-39 Expert said:


> P-47 didn't see combat until April 1943. I doubt the Spitfire doubled in weight but horsepower roughly doubled also. Weight did matter when the engine only developed 1150hp. Tell the Soviets that the P-39 was rubbish. And it had a radio, and armor plate/glass, and large caliber guns, and the engine wasn't crap. It was definitely a military machine. As long as you keep saying obviously false statements like this I will keep disagreeing with you.


Instead of pondering and doubting why not look something up. Everything you say the P-39 had you want to take off, armour guns radios the lot. Thats why I havnt a clue what your point is.


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## SaparotRob (Jul 10, 2021)

I commend P-39 Expert. No joke. Regardless of position or argument, he has always been civil and polite no matter how heated or derisive comments got. 
I hope I can do as well if I’m involved in a controversial discussion.

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## buffnut453 (Jul 10, 2021)

P-39 Expert said:


> I doubt the Spitfire doubled in weight but horsepower roughly doubled also.



You can doubt that the Spitfire doubled in weight but why don't you get off your backside and check it for yourself instead of simply questioning other people's statements and refusing to back down? 

Jeffrey Quill's book on the Spitfire definitely made the point that the Spitfire doubled in weight during its lifetime. Oh, and Jeffrey Quill was a test pilot...so maybe you'll trust his statements? Or, since he was British, does that automatically remove him as a trustworthy source?


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## pbehn (Jul 10, 2021)

buffnut453 said:


> You can doubt that the Spitfire doubled in weight but why don't you get off your backside and check it for yourself instead of simply questioning other people's statements and refusing to back down?
> 
> Jeffrey Quill's book on the Spitfire definitely made the point that the Spitfire doubled in weight during its lifetime. Oh, and Jeffrey Quill was a test pilot...so maybe you'll trust his statements? Or, since he was British, does that automatically remove him as a trustworthy source?


Dont bring another "joe pilot" into it! 

 P-39 Expert
The first Spitfires had a two blade wooden prop, look at the last 5 blade and six blade props how much heavier are they? Then there is swapping 8 mgs for 4 cannon. Installing a hydraulic system, armour plate and glass, self sealing tanks, beefed up undercarriage, thicker gauge duralumin on the wings, more and bigger radiators full of water/glycol. Oh the Griffon engine was obviously bigger and needed stronger supports then there was more fuel and oil and blah blah blah, and dont forget the IFF and oxygen.

Edit I forgot the ballast in the tail which from memory was about 140Lb of lead.


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## pbehn (Jul 10, 2021)

SaparotRob said:


> I commend P-39 Expert. No joke. Regardless of position or argument, he has always been civil and polite no matter how heated or derisive comments got.
> I hope I can do as well if I’m involved in a controversial discussion.


He does, he just counters any fact with his opinion that the fact isnt true, or rarely true or demands another fact to score in his newly moved goal.


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## buffnut453 (Jul 10, 2021)

SaparotRob said:


> I commend P-39 Expert. No joke. Regardless of position or argument, he has always been civil and polite no matter how heated or derisive comments got.
> I hope I can do as well if I’m involved in a controversial discussion.



Yes, but he also brings a lot of passive aggressive nonsense to the table by refusing to respond to questions and constant deflecting or citing opinions rather than engaging with the facts that others bring to the table. Passive aggression is not being polite. It's disrespectful and prevents an actual debate about the facts of the case.

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## P-39 Expert (Jul 10, 2021)

Greg Boeser said:


> Well, on paper, the P-39 is faster, has a better climb rate, and a heavier offensive battery than a P-40.
> But, the P-40 rolled better, held a turn better, and could take more punishment. Plus it could carry more external armament. And had better range. And was easier to service. There is a reason that P-39 equipped units in the field clamored for better aircraft. By the time better P-39s became available, P38s, P-47s, and P-51s were being produced in quantity. As to the USSR, the P-39 was the best on hand when it was introduced there. It was faster and more maneuverable, and had better pilot visibility, radios, etc., than the early LaGGs, MiGs, and even Yaks, and head and shoulders above the I-153s and I-16s the Russian pilots had been flying.


That's the whole thing, the timing. The P-39 was available when the war started for the US, along with the P-40 and the F4F. That's what we had to go to war with in 1942. P-38s, P-47s and P-51s were in production but they didn't get into the fight until late '42 (P-38), spring '43 (P-47) and late '43 (Merlin P-51). And by the time the P-47s were getting into combat the best P-39 model (N) was already out of production. Hard to compare later planes with earlier planes.

Seems to me that the AAF should have improved 1942 P-39 performance asap, especially since it was so easy to just remove some redundant/unnecessary items at forward combat bases. The improved climb and ceiling would have been of great use at NG and Guadalcanal. Weight was finally reduced by 650lbs at Guadalcanal in October '42, but by then AAF units knew they would shortly get P-38s. 

With reduced weight it could have been used very effectively as high cover for P-40s. The P-40 was a very effective combat plane with good maneuverability, heavy firepower and rugged construction when it had top cover. Without top cover it was at a severe disadvantage. The Soviets used the P-39 and P-40 this way before they had acquired enough P-39s to form their own separate groups. 

Clean P-39s and P-40s had about the same range, 600 and 650mi respectively per AHT and the calculations from the pilot's manuals made earlier in this thread. And both carried an external tank. The P-40 held 30gal more internal fuel but that was offset by the P-39's higher cruising speed and smaller allowance for takeoff and climb. The P-40 was regarded by AAF pilots as being slightly more maneuverable but rate of turn figures gave the P-39 a slight edge, so I would regard maneuverability as about the same. Faster, a good bit better climb and ceiling, and about the same range and maneuverability. Remember this is 1942 and the other planes are not yet available.


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## pbehn (Jul 10, 2021)

Mustang Mk Is were in production and the USA took the the ones not shipped for their own use, the time they took to see service is how long it takes to get a plane in service. Why was the P-39N taken out of production and replaced with something not so good?


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## Milosh (Jul 10, 2021)

After the arrival of the initial aircraft in the UK in October 1941, the first Mustang Mk Is entered service in *January 1942*, the first unit being 26 Squadron RAF.

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## SaparotRob (Jul 10, 2021)

That was a great link. 26 Squadron flew a bunch of airplanes I've never knew of. De Haviland Hyena. Some other great names too. I forgot I was looking up the Mustang Mk I !


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## pbehn (Jul 10, 2021)

SaparotRob said:


> That was a great link. 26 Squadron flew a bunch of airplanes I've never knew of. De Haviland Hyena. Some other great names too. I forgot I was looking up the Mustang Mk I !


I think they ran out of names, who would admit to flying a Dormouse?

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## Shortround6 (Jul 10, 2021)

P-39 Expert said:


> The P-40 was a very effective combat plane with good maneuverability, heavy firepower and rugged construction when it had top cover. Without top cover it was at a severe disadvantage.


Top cover= P-40F. 

They tried taking weight out of the P-40, See how that went.



http://www.wwiiaircraftperformance.org/P-40/P-40N_Operational_Suitability.pdf

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## BiffF15 (Jul 10, 2021)

P-39 Expert said:


> P-47 didn't see combat until April 1943. I doubt the Spitfire doubled in weight but horsepower roughly doubled also. Weight did matter when the engine only developed 1150hp. Tell the Soviets that the P-39 was rubbish. And it had a radio, and armor plate/glass, and large caliber guns, and the engine wasn't crap. It was definitely a military machine. As long as you keep saying obviously false statements like this I will keep disagreeing with you.


P-39 Expert,

Context can be everything. The Russians didn’t have a product that was as good as the ‘39, plus it was free, and the motor took pretty good abuse above the book numbers, and it was available in quantity, and it was free, and they fought to it’s strengths (low altitude, short range). OF COURSE THEY LIKED IT. In the context of the battle plan they liked to operate in (low altitude, close to the front, over your own country) it was perfect. Did I mention it was free, and available? The rest of the Allies had availability of other “better” aircraft. So you have your choice of a good product (A) which is better than product (B). Which do you keep and which do you give away? It’s a rhetorical question, you give away B. Which is exactly what the Brit’s did. And the US. We were probably happy that the Russians liked an aircraft we didn’t so there was no arguing over what we kept vice gave away via lend lease.

And since you are so hung up on test pilots, don’t you think the Brits used theirs while evaluating the P39? Also, look at it in the context of the Brits. They had been flying combat before the P39 arrived, and they came to the conclusion that it was inferior to what they already had, or would soon have, and got rid of it.

Here we are 124 pages into ANOTHER thread on the P39, all because literally hundreds of guys couldn’t figure out in WW2 what you have figured out 70+ years later. How could they have been so far off?

Cheers,
Biff

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## pbehn (Jul 10, 2021)

BiffF15 said:


> P-39 Expert,
> 
> Context can be everything. The Russians didn’t have a product that was as good as the ‘39, plus it was free, and the motor took pretty good abuse above the book numbers, and it was available in quantity, and it was free, and they fought to it’s strengths (low altitude, short range). OF COURSE THEY LIKED IT. In the context of the battle plan they liked to operate in (low altitude, close to the front, over your own country) it was perfect. Did I mention it was free, and available? *The rest of the Allies had availability of other “better” aircraft. So you have your choice of a good product (A) which is better than product (B). Which do you keep and which do you give away? It’s a rhetorical question, you give away B. Which is exactly what the Brit’s did. * And the US. We were probably happy that the Russians liked an aircraft we didn’t so there was no arguing over what we kept vice gave away via lend lease.
> 
> ...


Great post but as far as the part in bold it wasnt in the UKs "gift" to give anything away. The UK had ordered it but it was nowhere near what they ordered and by 1941 it would be supplied on Lend Lease. There was no argument for the UK having it. It couldnt be used from the UK itself and in N Africa it added nothing to what was already there. In Russia anything was useful for something, like Gloster Gladiators on Malta. The Po-2 had a military use in Russia and it had a maximum speed on par with a front line fighters stall speed, such things can happen on a front thousands of miles long. The P-39 was used in UK to familiarise Russian pilots and engineers on its future use in the Soviet Union, just as pilots and ground crew went to Russia to familiarise Russians with the Hurricane in exactly the same period.

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## nuuumannn (Jul 10, 2021)

Shortround6 said:


> Great, naked pilot with 20lb parachute.



 

Imagine the surprise of the Japanese pilots watching butt-nekkid P-39 pilots descending past them under their parachutes...



GrauGeist said:


> If a GI weighed 140 pounds, he was either suffering from dysentary or was a POW.



And naked...



Just Schmidt said:


> Anybody sharing in my experience of being relegated a status as below average, is recommended to join us in the movement for equal heights.



Well, I'm 6' 2" and weigh over 100 kgs and I definitely struggle to fit in most WW2 fighters. In a Spitfire I have to sit with my head bowed forward with the canopy closed. In a Buchon (Bf 109) I can't close the canopy. There's room for my bulky frame and fat head in a P-51D though...

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## Thumpalumpacus (Jul 10, 2021)

BiffF15 said:


> P-39 Expert,
> The Russians didn’t have a product that was as good as the ‘39, plus it was free, and the motor took pretty good abuse above the book numbers, and it was available in quantity, and it was free, and they fought to it’s strengths (low altitude, short range). OF COURSE THEY LIKED IT. In the context of the battle plan they liked to operate in (low altitude, close to the front, over your own country) it was perfect. [...]
> 
> Cheers,
> Biff



Doctrine does actually matter. The -39 didn't provide anything the USAAC could use it didn't already have from a more-trusted company, and could not provide any capability that other planes couldn't.

The Russians could use the -39 well because, in part, their doctrine accepted and used short-range, high-speed, limited altitude sorties.

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## Greg Boeser (Jul 10, 2021)

And we sent the 100 octane avgas that fueled them.

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## FLYBOYJ (Jul 11, 2021)

P-39 Expert said:


> Tell the Soviets that the P-39 was rubbish. And it had a radio, and armor plate/glass, and large caliber guns, and the engine wasn't crap.



And it also had armor around the prop gearbox that they were smart enough not to remove. 




P-39 Expert said:


> That's the whole thing, the timing. The P-39 was available when the war started for the US, along with the P-40 and the F4F. That's what we had to go to war with in 1942. P-38s, P-47s and P-51s were in production but they didn't get into the fight until late '42 (P-38), spring '43 (P-47) and late '43 (Merlin P-51). And by the time the P-47s were getting into combat the best P-39 model (N) was already out of production. Hard to compare later planes with earlier planes.
> 
> Seems to me that the AAF should have improved 1942 P-39 performance asap, especially since it was so easy to just remove some redundant/unnecessary items at forward combat bases. The improved climb and ceiling would have been of great use at NG and Guadalcanal. Weight was finally reduced by 650lbs at Guadalcanal in October '42, but by then AAF units knew they would shortly get P-38s.
> 
> ...


Would have, could have, should have - actually what you say actually happened to a point when you look at the performance of V fighter command P-39 squadrons through the summer of 42 and some of the operations they were flying, they were definitely holding the line to a point. Holding the line however wasn't good enough. In the spirit of Groundhog day, I'll repeat, everything changed when the P-38 arrived.

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## GrauGeist (Jul 11, 2021)

It was the P-40, however, that was able to counter the Japanese and forced the Japanese to fight on their terms, once they figured out that the A6M and KI-43 were not energy fighters.
Of all the PTO/CBI pilot accounts I've read from the early days of the war, where tactics evolved and solutions against the IJA and IJN fighters were taken into account, none included any accounts from P-39 pilots.

None.

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## pbehn (Jul 11, 2021)

FLYBOYJ said:


> In the spirit of Groundhog day, I'll repeat, everything changed when the P-38 arrived.


Only because the Americans wriggled out of the contract with the British, or was it the other way around.

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## P-39 Expert (Jul 11, 2021)

buffnut453 said:


> You can doubt that the Spitfire doubled in weight but why don't you get off your backside and check it for yourself instead of simply questioning other people's statements and refusing to back down?
> 
> Jeffrey Quill's book on the Spitfire definitely made the point that the Spitfire doubled in weight during its lifetime. Oh, and Jeffrey Quill was a test pilot...so maybe you'll trust his statements? Or, since he was British, does that automatically remove him as a trustworthy source?


Spitfire I weighed 5819lbs. Spitfire XIV weighed 8500lbs. Hardly double. Late war Spitfires did have 2000hp engines though.


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## XBe02Drvr (Jul 11, 2021)

pbehn said:


> Only because the Americans wriggled out of the contract with the British, or was it the other way around.


As I understand it (possibly wrong), didn't the British, in an attempt to maintain engine commonality and avoid turbocharger complexity, wind up spec-ing a Lightning that couldn't be competitive in the ETO? IIRC, the British-speced machines were used stateside as trainers, as they were deemed unsuitable for combat.


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## pbehn (Jul 11, 2021)

P-39 Expert said:


> Spitfire I weighed 5819lbs. Spitfire XIV weighed 8500lbs. Hardly double. Late war Spitfires did have 2000hp engines though.


Do you read anything? Why do you quote one of the heaviest versions of the Mk I? The prototype, ballasted for guns weighed 5,322Lbs, why dont you quote the last versions of the Spitfire/Seafire which were up to 12,000Lb loaded weight. And no, I am not going to get into dates and uses and name definitions. The first Spitfires only had circa 660BHP of thrust available at take off so the growth was bigger than at first sight.


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## pbehn (Jul 11, 2021)

XBe02Drvr said:


> As I understand it (possibly wrong), didn't the British, in an attempt to maintain engine commonality and avoid turbocharger complexity, wind up spec-ing a Lightning that couldn't be competitive in the ETO? IIRC, the British-speced machines were used stateside as trainers, as they were deemed unsuitable for combat.


Post 2167 by Flyboy

_By June 1941, the War Ministry had cause to reconsider their earlier aircraft specifications based on experience gathered in the Battle of Britain and The Blitz.[63]​ British displeasure with the Lockheed order came to the fore in July, and on 5 August 1941 they modified the contract such that 143 aircraft would be delivered as previously ordered, to be known as "Lightning (Mark) I," and 524 would be upgraded to US-standard P-38E specifications with a top speed of 415 mph (668 km/h) at 20,000 ft (6,100 m) guaranteed, to be called "Lightning II" for British service.[63]​ Later that summer an RAF test pilot reported back from Burbank with a poor assessment of the "tail flutter" situation, and the British cancelled all but three of the 143 Lightning Is.[63]​ *As a loss of approximately US$15M was involved, Lockheed reviewed their contracts and decided to hold the British to the original order. Negotiations grew bitter and stalled.[63]​ Everything changed after the 7 December 1941 attack on Pearl Harbor after which the United States government seized some 40 of the Model 322s for West Coast defense;[64]​ subsequently all British Lightnings were delivered to the USAAF starting in January 1942. The USAAF lent the RAF three of the aircraft, which were delivered by sea in March 1942[65]​ and were test flown no earlier than May[66]​ at Cunliffe-Owen Aircraft Swaythling, the Aeroplane and Armament Experimental Establishment and the Royal Aircraft Establishment.[63]​ The A&AEE example was unarmed, lacked turbochargers and restricted to 300 mph (480 km/h); though the undercarriage was praised and flight on one engine described as comfortable.[67]​ *These three were subsequently returned to the USAAF; one in December 1942 and the others in July 1943.[65]​ Of the remaining 140 Lightning Is, 19 were not modified and were designated by the USAAF as *RP-322-I* ('R' for 'Restricted', because non-counter-rotating propellers were considered more dangerous on takeoff), while 121 were converted to non-turbo-supercharged counter-rotating V-1710F-2 engines and designated *P-322-II*. All 121 were used as advanced trainers; a few were still serving that role in 1945.[66]​ A few RP-322s were later used as test modification platforms such as for smoke-laying canisters. The RP-322 was a fairly fast aircraft below 16,000 ft (4,900 m) and well-behaved as a trainer_

I think most of this came from Bodie's book _The Lockheed P-38 Lightning: The Definitive Story of Lockheed's P-38 Fighter_


I think if what our "expert" says was really true, Bell "would have" followed suit. Maybe Lockheed had better Lawyers?

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## buffnut453 (Jul 11, 2021)

P-39 Expert said:


> Spitfire I weighed 5819lbs. Spitfire XIV weighed 8500lbs. Hardly double. Late war Spitfires did have 2000hp engines though.



Why are you picking out the MkXIV? The Spitfire design had considerable further development beyond that mark.

For example, the Spitfire Mk.24 had a max weight at take-off of 12,150 lbs (Source: Pilot's Notes - https://ww2aircraft.net/forum/attachments/pilots-notes-for-spitfire-22-24-pdf.613338/). There's also the Seafire FR Mk 47 had a max weight of 12,900 lbs (Source: "Supermarine Seafire F.XV, F.VXII, F.45, F/FR.46, F/FR.47 and Seafang" by Kevin Darling, p.44).

So, YES, the later versions of the Spitfire (and Seafire) had more than double the all-up weight of the MkI. Jeffrey Quill was correct in his statement. 

Please, stop the cherry-picking nonsense and start learning.

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## SaparotRob (Jul 11, 2021)

XBe02Drvr said:


> As I understand it (possibly wrong), didn't the British, in an attempt to maintain engine commonality and avoid turbocharger complexity, wind up spec-ing a Lightning that couldn't be competitive in the ETO? IIRC, the British-speced machines were used stateside as trainers, as they were deemed unsuitable for combat.


I thought superchargers weren't allowed to be shipped to foreign powers so the "castrated Lightning" came to be.


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## P-39 Expert (Jul 11, 2021)

pbehn said:


> Do you read anything? Why do you quote one of the heaviest versions of the Mk I? The prototype, ballasted for guns weighed 5,322Lbs, why dont you quote the last versions of the Spitfire/Seafire which were up to 12,000Lb loaded weight. And no, I am not going to get into dates and uses and name definitions. The first Spitfires only had circa 660BHP of thrust available at take off so the growth was bigger than at first sight.


Prototypes don't fly combat missions, and I looked all over but couldn't find a 12000lb Spitfire.


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## buffnut453 (Jul 11, 2021)

P-39 Expert said:


> Prototypes don't fly combat missions, and I looked all over but couldn't find a 12000lb Spitfire.



Then how about the Mk22/24 Pilot's Notes that I referenced? Click on the link and it'll take you to the original document.

EDIT: The weight figures are on p.31 of the Pilot's Notes.


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## P-39 Expert (Jul 11, 2021)

buffnut453 said:


> Why are you picking out the MkXIV? The Spitfire design had considerable further development beyond that mark.
> 
> For example, the Spitfire Mk.24 had a max weight at take-off of 12,150 lbs (Source: Pilot's Notes - https://ww2aircraft.net/forum/attachments/pilots-notes-for-spitfire-22-24-pdf.613338/). There's also the Seafire FR Mk 47 had a max weight of 12,900 lbs (Source: "Supermarine Seafire F.XV, F.VXII, F.45, F/FR.46, F/FR.47 and Seafang" by Kevin Darling, p.44).
> 
> ...


Congratulations, you found one mark that weighed over 12000lbs with full external fuel that first flew a full year AFTER the end of WW2. WW2 Spitfires weighed around 8500lbs max with no external tanks. Who's cherry picking now?


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## buffnut453 (Jul 11, 2021)

P-39 Expert said:


> Congratulations, you found one mark that weighed over 12000lbs with full external fuel that first flew a full year AFTER the end of WW2. WW2 Spitfires weighed around 8500lbs max with no external tanks. Who's cherry picking now?



You're the one who's adding the caveat of the end of the WW2. My statement was that the Spitfire doubled it's max all-up weight during the lifetime of the design. My statement is correct. Now (yet again) you're trying to duck out of being proven wrong.

As for WW2 Spitfires, how about the PR Mk XIX with an all-up weight of 10,450lb? Or even the Mk 22 which flew before the end of the war with a max weight of 11,350lb? Both considerably more than 8,500 lbs!

For once can you just admit you were wrong?


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## pbehn (Jul 11, 2021)

P-39 Expert said:


> Prototypes don't fly combat missions, and I looked all over but couldn't find a 12000lb Spitfire.


I knew you would start this, you have been given weights of the Spitfire range, the weight you quoted was of a Spitfire with armour gun heating CS props etc etc etc all imposed by the client after the initial contract. The issue is that the client was always demanding more stuff which added weight. The prototype P-39 was used for combat data and you have whinged whined muled and puked about everything the British asked to be put on the P-39, which was put on the Spitfire. The P-39 was also tried out for carrier operations by the British and the USA both didnt proceed with it.


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## pbehn (Jul 11, 2021)

buffnut453 said:


> You're the one who's adding the caveat of the end of the WW2. My statement was that the Spitfire doubled it's max all-up weight during the lifetime of the design. My statement is correct. Now (yet again) you're trying to duck out of being proven wrong.
> 
> As for WW2 Spitfires, how about the PR Mk XIX with an all-up weight of 10,450lb? Or even the Mk 22 which flew before the end of the war with a max weight of 11,350lb? Both considerably more than 8,500 lbs!
> 
> For once can you just admit you were wrong?


I think we have been here before. I doubt it happened, it didnt happen very often, it didnt happen in a certain time frame. Complete pettyfoggery and groundhoggery.


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## buffnut453 (Jul 11, 2021)

pbehn said:


> I think we have been here before. I doubt it happened, it didnt happen very often, it didnt happen in a certain time frame. Complete pettyfoggery and groundhoggery.



Yeah...I know. He was proven wrong about the British demanding an "unnecessary" "additional" cockpit heater. He was proven wrong about the requirement for nose armour for the gearbox. He was proven wrong about the "useless" 30cals (which the USAAF didn't remove from many operational fighters in a combat zone). He was proven wrong about BoB fighters being hardly able to reach 30,000ft. He was proven wrong on his statement that Britain unnecessarily increased the weight of the P-400 to weasel out of the contract (Britain accepted the type despite a specially prepared airframe still failing to reach the minimum performance figures). 

He refused to accept defeat on any of those topics so it's entirely unsurprising that he lacks the grace to admit he was wrong about the Spitfire's incredible (unprecedented) growth during it's lifetime.

Bear in mind that the Spit Mk 24 could reach 30,000 ft in about 8 mins despite that increase in weight compared to the earlier marks.

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## pbehn (Jul 11, 2021)

buffnut453 said:


> Bear in mind that the Spit Mk 24 could reach 30,000 ft in about 8 mins despite that increase in weight compared to the earlier marks.


Which proves all this BS about weight and rate of climb is BS. How much did a EE Lightning or Saturn V rocket weigh? It isnt a question of just weight, it is thrust lift drag etc.


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## GregP (Jul 11, 2021)

There are formulas for estimating rate of climb for an aircraft that has been tested and has a weight, horsepower, and rate of climb and you want to change one of them. But, changing more than one usually requires a new test for an accurate answer. still, if HP goes up by 150 and weight only changes by maybe a few %, the estimate will be close to real.

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## pbehn (Jul 11, 2021)

GregP said:


> There are formulas for estimating rate of climb for an aircraft that has been tested and has a weight, horsepower, and rate of climb and you want to change one of them. But, changing more than one usually requires a new test for an accurate answer. still, if HP goes up by 150 and weight only changes by maybe a few %, the estimate will be close to real.


If you can keep the engine cool enough to keep working and be ok to do it again and again until the next service.


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## pbehn (Jul 11, 2021)

P-39 Expert said:


> Congratulations, you found one mark that weighed over 12000lbs with full external fuel that first flew a full year AFTER the end of WW2. WW2 Spitfires weighed around 8500lbs max with no external tanks. Who's cherry picking now?


Actually it was two marks, why do you say it is one? Why is internal and external weight a criteria, it is weight, isnt it? You have used external stores when advocating the qualities of the P-39. So, to your question about who is cherry picking, you are, it is all you ever do. It doesnt matter if it is one Marque or even one aeroplane had a loaded weight of over 12,000Lbs it is a FACT, so your doubts were once again WRONG. In fact the weight of the Spitfire all up weight more than doubled from prototype to final versions and the prototype was ballasted for 8 Mgs not some piddling, play-at-it, P-39 style of armament and that was from 1937.

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## Thumpalumpacus (Jul 11, 2021)

buffnut453 said:


> Yeah...I know. He was proven wrong about the British demanding an "unnecessary" "additional" cockpit heater. He was proven wrong about the requirement for nose armour for the gearbox. He was proven wrong about the "useless" 30cals (which the USAAF didn't remove from many operational fighters in a combat zone). He was proven wrong about BoB fighters being hardly able to reach 30,000ft. He was proven wrong on his statement that Britain unnecessarily increased the weight of the P-400 to weasel out of the contract (Britain accepted the type despite a specially prepared airframe still failing to reach the minimum performance figures).
> 
> He refused to accept defeat on any of those topics so it's entirely unsurprising that he lacks the grace to admit he was wrong about the Spitfire's incredible (unprecedented) growth during it's lifetime.
> 
> Bear in mind that the Spit Mk 24 could reach 30,000 ft in about 8 mins despite that increase in weight compared to the earlier marks.



In a phrase, the difference between a -39 and a Spit: _growth potential_.

I believe that is why the P-39 was cast aside. Granted, the P-39 grew into the P-63, but I think it's more than fair to point out that over its lifetime, the Spit grew even further beyond what was already the superior design.

The Spitfire's design allowed for more useful upgrading, keeping the fighter relevant through the end of the war.

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## Snautzer01 (Jul 12, 2021)

Found this. I think it is a russia report on the corkscrewing behaviour of the p-39. Perhaps to some use in this endless tall tail.


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## Snautzer01 (Jul 12, 2021)




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## Snautzer01 (Jul 12, 2021)



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## Snautzer01 (Jul 12, 2021)

to lazy to go through this thread , but have we seen this??

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## Juha3 (Jul 12, 2021)

P-39 Expert said:


> Spitfire I weighed 5819lbs. Spitfire XIV weighed 8500lbs. Hardly double. Late war Spitfires did have 2000hp engines though.


Yes, the first production Spit I weighted full loaded 5,819 lbs. Did you notice that British used 200 lbs for pilot and parachute? According to you that is too much, or do you believe British were better fed than US citizens in 1939 - 41? BTW, what is your source for your claim "_Average American man in the Army in WWII was 5'8" and weighed 140lbs" _in your message #2,429? The last Spit Mk which saw service during the WWII was F Mk 21, Typical service weight (without external load) 9,420 lbs, max with 90 gal blister tank, 10,202 lbs.

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## Peter Gunn (Jul 12, 2021)

At 6' 2.5" I'd like to know how's the weather down there?



Just Schmidt said:


> As one who stands about two turds and a half above ground fully stretched, I strongly protest against this recent fixation on height, first disguised as ceiling of aircraft but now blatantly heightist and clearly demeaning of us who are vertically challenged.
> 
> Anybody sharing in my experience of being relegated a status as below average, is recommended to join us in the movement for equal heights.

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## XBe02Drvr (Jul 12, 2021)

Just Schmidt said:


> As one who stands about two turds and a half above ground fully stretched, I strongly protest against this recent fixation on height, first disguised as ceiling of aircraft but now blatantly heightist and clearly demeaning of us who are vertically challenged.
> Anybody sharing in my experience of being relegated a status as below average, is recommended to join us in the movement for equal heights.


Consider yourself fortunate you're not banging your head on door frames and bending your knees backward to get in and out of MGBs, Triumph Spitfires, and J3 Cubs!
Get yourself a pair of these:





And quityerbellyachin!

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## pbehn (Jul 12, 2021)

Juha3 said:


> Yes, the first production Spit I weighted full loaded 5,819 lbs. Did you notice that British used 200 lbs for pilot and parachute? According to you that is too much, or do you believe British were better fed than US citizens in 1939 - 41? BTW, what is your source for your claim "_Average American man in the Army in WWII was 5'8" and weighed 140lbs" _in your message #2,429? The last Spit Mk which saw service during the WWII was F Mk 21, Typical service weight (without external load) 9,420 lbs, max with 90 gal blister tank, 10,202 lbs.


The first production Spitfires changed weight as they were being produced and after. The gun heating system was introduced during production. They then replaced the wooden prop with variable pitch and then CS props. They fitted armour initially to the bulkhead and then behind the pilot. It is all completely academic though. The exhaust heating system from fish tail exhausts increased thrust and so top speed. The variable pitch and VP and CS props + 100 octane fuel completely transformed performance giving a much higher ceiling, top speed plus rate of climb with 30% less distance needed for take off run.


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## GrauGeist (Jul 12, 2021)

Wonder what the weight difference was between the original two-bladed prop and it's replacement?


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## pbehn (Jul 12, 2021)

GrauGeist said:


> Wonder what the weight difference was between the original two-bladed prop and it's replacement?


From Wiki The early Mk Is were powered by the 1,030 hp (768 kW) Merlin Mk II engine driving an Aero-Products "Watts" 10 ft 8 in (3.3 m) diameter two-blade wooden fixed-pitch propeller, weighing 83 lb (38 kg). From the 78th production airframe, the Aero Products propeller was replaced by a 350 lb (183 kg) de Havilland 9 ft 8 in (2.97 m) diameter, three-bladed, two-position, metal propeller, which greatly improved take-off performance, maximum speed and the service ceiling.

I make that +267Lb

Then "In June 1940 de Havilland began manufacturing a kit to convert their two pitch propeller unit to a constant speed propeller. Although this propeller was a great deal heavier than the earlier types (500 lb (227 kg) compared with 350 lb (183 kg)) it provided another substantial improvement in take-off distance and climb rate. "

I make that +417 Lb compared to the Watts two blade prop.

Also "Starting in September 1940, IFF equipment was installed. This weighed about 40 lb (18 kg) and could be identified by wire aerials strung between the tailplane tips and rear fuselage. "

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## GrauGeist (Jul 12, 2021)

So that's a considerable jump in weight, especially at the front of the airframe - I wonder what adjustments were made to preserve CoG.


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## Juha3 (Jul 12, 2021)

pbehn said:


> The first production Spitfires changed weight as they were being produced and after. The gun heating system was introduced during production. They then replaced the wooden prop with variable pitch and then CS props. They fitted armour initially to the bulkhead and then behind the pilot. It is all completely academic though. The exhaust heating system from fish tail exhausts increased thrust and so top speed. The variable pitch and VP and CS props + 100 octane fuel completely transformed performance giving a much higher ceiling, top speed plus rate of climb with 30% less distance needed for take off run.


5,819 lbs was the fully loaded weight of K 9787, the first production Spitfire, in August 1938. Source _Price, The Spitfire Story_ (1995) p.81


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## pbehn (Jul 12, 2021)

GrauGeist said:


> So that's a considerable jump in weight, especially at the front of the airframe - I wonder what adjustments were made to preserve CoG.


From what Ive read here the CoG moving forward is less serious than moving back, and they were putting stuff like IFF and radios etc behind the CoL. 

I read in a book years ago that the boffins were concerned about putting armour behind the pilots in Hurricanes, the pilots in France werent, they made and put in their own.

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## pbehn (Jul 12, 2021)

Juha3 said:


> 5,819 lbs was the fully loaded weight of K 9787, the first production Spitfire, in August 1938. Source _Price, The Spitfire Story_ (1995) p.81


I am not disagreeing, but as per my other post if it remained in service it will have been fitted with other stuff like props and armour IFF etc. The gun heating system was installed on the 61st Spitfire. They are all called Mk Is even when they started fitting cannon to them a cannon armed Mk I became a Mk IB and all those with 8 Mgs retrospectively were MkIAs.


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## MikeMeech (Jul 12, 2021)

pbehn said:


> From what Ive read here the CoG moving forward is less serious than moving back, and they were putting stuff like IFF and radios etc behind the CoL.
> 
> I read in a book years ago that the boffins were concerned about putting armour behind the pilots in Hurricanes, the pilots in France werent, they made and put in their own.


Hi
The book 'Knights of the Skies - Armour protection for the British fighting aeroplanes' by Michael C Fox, appears to differ in opinion to your statement, pages 218-220 has the following for example:













Mike

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## pbehn (Jul 12, 2021)

MikeMeech said:


> Hi
> The book 'Knights of the Skies - Armour protection for the British fighting aeroplanes' by Michael C Fox, appears to differ in opinion to your statement, pages 218-220 has the following for example:
> View attachment 632000
> 
> ...


Thanks, it was something to do with the admin or certification of what is described being flight tested. It may have been the plan to switch all Hurricanes to Rotol props before going to France but things didnt go to plan in this is a picture of Cobber Kain in France with his Hurricane carrying a Watts two blade prop. 'Cobber' Kain - first RAF Hurricane Ace, first RAF air ace of the WWII, and first to receive the Distinguished Flying Cross - The Aviation Geek Club.

My point was about people being much more concerned about the CoG going aft than fore

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## SaparotRob (Jul 12, 2021)

MikeMeech said:


> Hi
> The book 'Knights of the Skies - Armour protection for the British fighting aeroplanes' by Michael C Fox, appears to differ in opinion to your statement, pages 218-220 has the following for example:
> View attachment 632000
> 
> ...


Thanks for that link. I enjoyed reading it.


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## Glider (Jul 12, 2021)

GrauGeist said:


> So that's a considerable jump in weight, especially at the front of the airframe - I wonder what adjustments were made to preserve CoG.


I only know a little on this but the weight gain did have to be carefully managed. The very first Spitfires with the initial two bladed prop were actually tail heavy and weights were added in the nose.
As has been mentioned this very quickly changed and they ended up with weights in the tail.

I said it had to be carefully managed in particular the Spit V. These were in service for a long time and a lot of extra kit was installed during this period. I read one book where the writer was promoted and transferred to a different station still on Spit V and the planes handling was dreadful. He looked into it finding that extra equipment had been installed but not as the instructions and this had played havoc with the Cog and handling.
He grounded the unit until it had all been removed and reinstalled correctly and the problem went away.

If anyone thinks this couldn't happen in more modern times I was talking to an ex Canadian engineer and he described an CF-5 which came in for a major update before being transferred. They found to their horror that over time equipment had been upgraded and replaced but not all the old cabling had been removed. They took approx 150Ib of cabling out that wasn't attached to anything.

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## buffnut453 (Jul 12, 2021)

Glider said:


> I only know a little on this but the weight gain did have to be carefully managed. The very first Spitfires with the initial two bladed prop were actually tail heavy and weights were added in the nose.
> As has been mentioned this very quickly changed and they ended up with weights in the tail.
> 
> I said it had to be carefully managed in particular the Spit V. These were in service for a long time and a lot of extra kit was installed during this period. I read one book where the writer was promoted and transferred to a different station still on Spit V and the planes handling was dreadful. He looked into it finding that extra equipment had been installed but not as the instructions and this had played havoc with the Cog and handling.
> ...



But surely all they needed to do was move the radio and IFF to fix things, right? Simples!

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## pbehn (Jul 12, 2021)

Glider said:


> The very first Spitfires with the initial two bladed prop were actually tail heavy and weights were added in the nose.
> As has been mentioned this very quickly changed and they ended up with weights in the tail.


It must have been well understood that a heavier prop was coming, that was the reason ROTOL was formed in 1937, and the Merlin III with a drive shaft that could take both ROTOL and de Havilland props started to be delivered from 1 July 1938.


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## FLYBOYJ (Jul 12, 2021)

Glider said:


> I only know a little on this but the weight gain did have to be carefully managed. The very first Spitfires with the initial two bladed prop were actually tail heavy and weights were added in the nose.
> As has been mentioned this very quickly changed and they ended up with weights in the tail.
> 
> I said it had to be carefully managed in particular the Spit V. These were in service for a long time and a lot of extra kit was installed during this period. I read one book where the writer was promoted and transferred to a different station still on Spit V and the planes handling was dreadful. He looked into it finding that extra equipment had been installed but not as the instructions and this had played havoc with the Cog and handling.
> ...


This happens all the time in the military and civilian world and I'd bet dollars to donuts it occurred during WW2


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## GrauGeist (Jul 12, 2021)

While not a weight issue, in the past, while working on older fire engines in extended service, I encountered considerable amounts of cabling left behind during equipment upgrades.
In some cases, still live.
It was frustrating, especially when trying to trouble-shoot problems.


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## nuuumannn (Jul 12, 2021)

buffnut453 said:


> For once can you just admit you were wrong?



"Never!" 

Attributed to Winston Churchill in 1940 and P-39 Expert in 2021...

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## nuuumannn (Jul 12, 2021)

Let's put it this way, if I were a mod I'd shut this down. It's pointless. You guys are tying yourselves in knots to prove this guy wrong and _he's not listening_.


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## GrauGeist (Jul 12, 2021)

nuuumannn said:


> Let's put it this way, if I were a mod I'd shut this down. It's pointless. You guys are tying yourselves in knots to prove this guy wrong and _he's not listening_.


It would be like a game of "whack-a-mole", though, because one P-39 thread gets closed and then another P-39 thread gets revived and hijacked.

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## 33k in the air (Jul 12, 2021)

nuuumannn said:


> Let's put it this way, if I were a mod I'd shut this down. It's pointless. You guys are tying yourselves in knots to prove this guy wrong and _he's not listening_.



Look, this can all end amicably if everyone simply admits the P-39 was the F-22 of its day.

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## wuzak (Jul 12, 2021)

33k in the air said:


> Look, this can all end amicably if everyone simply admits the P-39 was the F-22 of its day.



Surely it is the F-23? Better than the F-22 but nobody wanted it....

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## GrauGeist (Jul 12, 2021)

wuzak said:


> Surely it is the F-23? Better than the F-22 but nobody wanted it....


Nose armor issues, I bet.

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## WARSPITER (Jul 12, 2021)

GrauGeist said:


> So that's a considerable jump in weight, especially at the front of the airframe - I wonder what adjustments were made to preserve CoG.


Perhaps the best answer would have been to reposition the engine further back - behind the pilot maybe so it would give a nice cog in the centre of the aircraft.
Would have been a far superior plane then - I wonder if anyone.... ever.... did.... that.... {slinks off quietly into the sunset...}

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## GrauGeist (Jul 12, 2021)

WARSPITER said:


> Perhaps the best answer would have been to reposition the engine further back - behind the pilot maybe so it would give a nice cog in the centre of the aircraft.
> Would have been a far superior plane then - I wonder if anyone.... ever.... did.... that.... {slinks off quietly into the sunset...}


Of course, you must be referring to the Piaggio P.119, right?

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## SaparotRob (Jul 12, 2021)

You guys like this thread more than you'd admit. Methinks Thou doth protest too loudly.

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## WARSPITER (Jul 12, 2021)

GrauGeist said:


> Of course, you must be referring to the Piaggio P.119, right?


Yeah that must be it... I knew there was a P at the start ......

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## GrauGeist (Jul 12, 2021)

SaparotRob said:


> You guys like this thread more than you'd admit. Methinks Thou doth protest too loudly.


Now seriously, where else would you learn what the weight of the P-39's radio control cable is?

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## SaparotRob (Jul 12, 2021)

Which is why I like this thread. You guys may be pointing out the obvious to each other but a lot of it was new to me.

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## nuuumannn (Jul 13, 2021)

SaparotRob said:


> You guys like this thread more than you'd admit. Methinks Thou doth protest too loudly.



You jest, my Lord, but methinks you are right in your deduction...

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## 33k in the air (Jul 13, 2021)

SaparotRob said:


> You guys like this thread more than you'd admit. Methinks Thou doth protest too loudly.



Cry 'Havoc!' and let slip the Iron Dogs of war.

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## buffnut453 (Jul 13, 2021)

33k in the air said:


> Cry 'Havoc!' and let slip the Iron Dogs of war.



Or the groundhogs!

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## DerAdlerIstGelandet (Jul 13, 2021)

nuuumannn said:


> Let's put it this way, *if I were a mod I'd shut this down.*It's pointless. You guys are tying yourselves in knots to prove this guy wrong and _he's not listening_.



Then we just have every other thread spammed with the same P-39 stuff.

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## Just Schmidt (Jul 13, 2021)

XBe02Drvr said:


> Consider yourself fortunate you're not banging your head on door frames and bending your knees backward to get in and out of MGBs, Triumph Spitfires, and J3 Cubs!
> Get yourself a pair of these:
> View attachment 631990
> 
> And quityerbellyachin!


Your concern is appreciated, but using a pair of those will just add extra weight and introduce stability issues that will surely send me tumbling, making me sorely regret the time I removed my nose armour.

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## P-39 Expert (Jul 13, 2021)

buffnut453 said:


> Yeah...I know. He was proven wrong about the British demanding an "unnecessary" "additional" cockpit heater. He was proven wrong about the requirement for nose armour for the gearbox. He was proven wrong about the "useless" 30cals (which the USAAF didn't remove from many operational fighters in a combat zone). He was proven wrong about BoB fighters being hardly able to reach 30,000ft. He was proven wrong on his statement that Britain unnecessarily increased the weight of the P-400 to weasel out of the contract (Britain accepted the type despite a specially prepared airframe still failing to reach the minimum performance figures).
> 
> He refused to accept defeat on any of those topics so it's entirely unsurprising that he lacks the grace to admit he was wrong about the Spitfire's incredible (unprecedented) growth during it's lifetime.
> 
> Bear in mind that the Spit Mk 24 could reach 30,000 ft in about 8 mins despite that increase in weight compared to the earlier marks.


Not proven wrong about any of those. Not wasting time proving them again.

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## P-39 Expert (Jul 13, 2021)

pbehn said:


> Which proves all this BS about weight and rate of climb is BS. How much did a EE Lightning or Saturn V rocket weigh? It isnt a question of just weight, it is thrust lift drag etc.


Weight and rate of climb are directly related when engine power remains constant.

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## XBe02Drvr (Jul 13, 2021)

Just Schmidt said:


> Your concern is appreciated, but using a pair of those will just add extra weight and introduce stability issues that will surely send me tumbling, making me sorely regret the time I removed my nose armour.


Maybe a gyro stabilizer? Those stilts will seriously lower your CoG.

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## nuuumannn (Jul 13, 2021)

DerAdlerIstGelandet said:


> Then we just have every other thread spammed with the same P-39 stuff.



Well, that's up to you guys as mods to control.


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## pbehn (Jul 13, 2021)

P-39 Expert said:


> Weight and rate of climb are directly related when engine power remains constant.


You simply REFUSE to read dont you? The introduction of variable speed props and then constant speed props completely changed rate of climb on the Spitfire, DESPITE increasing weight by over 400Lbs. It changed again with a different prop on the MkII. What is the point in a discussion where you refuse to read or accept anything? This is not controversial or special knowledge only understood by experts it is common knowledge which can be found anywhere on the net.

When first tested the Spitfire was slower than expected, so they took off the "climbing" prop and put on one optimised for speed. On the ground with a two blade wooden prop only around 660BHP was available because at max revs the prop was stalled so the power produced little thrust.

It isnt only the Spitfire, what did paddle blade props do for many A/C especially the P-47?

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## Snautzer01 (Jul 13, 2021)

DerAdlerIstGelandet said:


> Then we just have every other thread spammed with the same P-39 stuff.


And in what thread should we post pictures of groundhogs then?

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## XBe02Drvr (Jul 13, 2021)

P-39 Expert said:


> Weight and rate of climb are directly related when engine power remains constant.





pbehn said:


> It isnt a question of just weight, it is thrust lift drag etc.


One Ex to another: t'aint that simple, lad. pbehn's pesky variables all add into the equation. Two engines of the same horsepower don't necessarily produce the same thrust unless they have identical props and superchargers rigged identically. Different marks of the same airframe almost certainly will not have identical drag coefficients due to different armament, antenna, and various other details. I could go on and on, but it's like conversing with a brick wall.

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## pbehn (Jul 13, 2021)

XBe02Drvr said:


> One Ex to another: t'aint that simple, lad. pbehn's pesky variables all add into the equation. Two engines of the same horsepower don't necessarily produce the same thrust unless they have identical props and superchargers rigged identically. Different marks of the same airframe almost certainly will not have identical drag coefficients due to different armament, antenna, and various other details. I could go on and on, but it's like conversing with a brick wall.



It is a complete waste of time, to improve the performance of the P-39 to get it to do 400MPH one mod was to change the exhausts to be in the direction of airflow, the Spitfires fish tail exhausts increased speed by about 10MPH with a slight increase in climb rate, so an increase in performance with no increase in power, all this has been posted here on this thread.

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## XBe02Drvr (Jul 13, 2021)

DerAdlerIstGelandet said:


> Then we just have every other thread spammed with the same P-39 stuff.


What was that cold war strategy? Containment?

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## Snautzer01 (Jul 13, 2021)

XBe02Drvr said:


> What was that cold war strategy? Containment?


No Mad. Kinda appropriate here i think.

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## pbehn (Jul 13, 2021)

P-39 Expert said:


> Weight and rate of climb are directly related when engine power remains constant.


With regard to Thumpalumpacus post below, engine power did not remain constant. The problem with the Allisson engine was it ran out of lungs at lower altitudes than others, but its power was changed by use of different fuels and gear ratios, you often quote this in your arguments. The power of the Merlin changed with use of different fuels which didnt increase weight, as well as different superchargers which did. The Merlin increased from circa 1,000BHP to circa 2,000BHP in 5 years, so 200BHP per year and airframes had to adjust to it and make use of it. The Hurricane MkII was 7 inches longer than a MkI. What do you do about an engine 7 inches longer in a P-39? Every small change in the engine requires almost a completely new airframe to be designed. Without these changes the P-51 would never have been an escort fighter with a Merlin engine, how would it perform with 1000BHP max?





Thumpalumpacus said:


> In a phrase, the difference between a -39 and a Spit: _growth potential_.
> 
> I believe that is why the P-39 was cast aside. Granted, the P-39 grew into the P-63, but I think it's more than fair to point out that over its lifetime, the Spit grew even further beyond what was already the superior design.
> 
> The Spitfire's design allowed for more useful upgrading, keeping the fighter relevant through the end of the war.

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## Shortround6 (Jul 13, 2021)

P-39 Expert said:


> Not proven wrong about any of those. Not wasting time proving them again.


You haven't proven many or indeed any of them.

_Saying_ they are wrong is not _proving_ they are wrong. 

WHEN did the British specify the "extra" stuff to get out of the contract? 
Which date/s or contract talks?
Why didn't Bell negotiate a lower performance standard if the British added weight? 
Instead Bell spent weeks modifying the 2nd production airframe to a point where it could make the lower margin of the speed band specified in the contract. 
Bell *KNEW *the P-400 didn't have a hope of meeting the contract specs weeks before the test flights. And yet it is the fault of the British?????
Bell had sold the French a plane that wouldn't meet the specs and the British got stuck with the contract. They had 3 opportunities, yet the original performance specs stood. 

You have said the stuff the British added was useless. 
As proof you trot out that the IFF wasn't needed in NG in 1942. Without a time machine what has that got to do with what the British needed in 1940-41 when fighting in British air space or over the Channel? 
Cockpit heater is useless????
Two are redundant, were the British ever offered the system using the hot air from the radiator duct? 
Self sealing fuel tanks are useless? 

You have one quote from a page in AHT saying the .30 cal guns had an effective range 200yds and turn that into the .30 cal guns were useless. I do like AHT but it is not infallible and I have shown there are several mistakes on that page. I would also note that the British did NOT rip the .30 cal guns out of the early P-40s and depend on the two cowl .50s. 

A bit more proof that A, .30 cal guns were useless in general and B, that the British could have known this in 1940 and early 1941,
At the time of the 2nd specification talks with Bell (Jan 1941) the British had gotten done with the BoB where over 99% of the fighting was done with .30/.303 guns. At that time the British were still arming the vast majority of their fighters with .303 guns including planning to fit 12 into the Hurricane II and the Typhoon. 
But somehow the British are "tricking" Bell by keeping the four wing guns that Bell agreed to put in for the French? 

Repeating wrong information many times does not make it true. 

You are the one claiming much of what we know about the P-39 is wrong and yet you offer little more than conjecture or unproven claims.

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## pbehn (Jul 13, 2021)

I just read recently that the requirement for IFF was a direct result of the "Battle of Barking Creek" 6 Sept 1939









Battle of Barking Creek - Wikipedia







en.wikipedia.org





In 2003, Patrick Bishop wrote that the incident exposed the inadequacies of RAF radar and identification procedures, leading to their being greatly improved by the time of the Battle of Britain, a view echoed in a 2012 publication by Philip Kaplan.[11]​[5]​

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## Peter Gunn (Jul 13, 2021)

Since no one took my .30 armed Airacobra idea seriously... *sniff*



1). No matter what anyone else says, I agree with 

 SaparotRob
I'm learning a lot and enjoying it fully.

2). 

 P-39 Expert
is a master troll. I've been around message boards too many years (read decades) not to recognize the traits of one. He may claim he's not, but if it walks like a duck...

I'm not saying that's a bad thing mind you, see number one (1) above.

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## SaparotRob (Jul 13, 2021)

I think it's time Expert 'fessed up. Admit this thread is a public service to educate those of us here who are aeronautically ignorant without us having to ask "obvious" or "silly" questions.

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## FLYBOYJ (Jul 13, 2021)



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## buffnut453 (Jul 13, 2021)

P-39 Expert said:


> Not proven wrong about any of those. Not wasting time proving them again.



They have ALL been proven wrong. You have made incorrect statements again and again and, when called on it, you deflect or change the entire argument. Just because you refuse to read or accept evidence does not mean that the evidence is invalid or that the proof is insufficient. You keep trotting out your own "proof" but most is centred in opinion not in fact. You've been asked for facts and to confirm information...and every time you have refused to answer. 

In the spirit of the Oscars, for excellence in film making, I hereby award you a Bert for supreme trollery.






Like any good troll, Bert is stumbling forward, constantly reaching out to clutch at any straws that perpetuate his world view regardless of the facts. His left eye is closed, connoting an inability to see everything that is in front of him, and a focus solely on a partial view of the world.

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## fubar57 (Jul 13, 2021)

DerAdlerIstGelandet said:


> Then we just have every other thread spammed with the same P-39 stuff.


He was already here this week, just a heads up and duck....https://ww2aircraft.net/forum/threads/the-p-39-a-zero-killer.40531/

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## fubar57 (Jul 13, 2021)

This may already be here, I dunno. I ain't lookin' back

​

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## SaparotRob (Jul 13, 2021)

I've watched it a few times already. I wonder if there was a LW equivalent of the Groundhog.


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## pbehn (Jul 13, 2021)

SaparotRob said:


> I've watched it a few times already. I wonder if there was a LW equivalent of the Groundhog.


I am sure they do but it will be three times as long, Charpy test in German is Kerbschlagbeigeversuch.

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## SaparotRob (Jul 13, 2021)

Gesundheit.

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## pbehn (Jul 13, 2021)

SaparotRob said:


> Gesundheit.


Heutevergleichmitgesternschwein?

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## SaparotRob (Jul 13, 2021)

Okay. I've stripped out the padding from both ends of the code. Now to 'figger out the middle. It's gonna' take some time. I got the "mit" part though.


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## Just Schmidt (Jul 13, 2021)

pbehn said:


> Heutevergleichmitgesternschwein?


Das immerwiedernocheinmahl?

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## GrauGeist (Jul 13, 2021)

SaparotRob said:


> I've watched it a few times already. I wonder if there was a LW equivalent of the Groundhog.


I'd say the Me210 would qualify for that title.
It was crap, yet the Hungarians were able to make it perform.

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## SaparotRob (Jul 13, 2021)

I took German in high school. My Yiddish just isn't working well enough right now. Dad told me he was the company translator during the war. Don't know how he did it.


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## pbehn (Jul 13, 2021)

SaparotRob said:


> Okay. I've stripped out the padding from both ends of the code. Now to 'figger out the middle. It's gonna' take some time. I got the "mit" part though.


Today is the as (with) yesterday. Kerbschlagbeigeversuch is a description prism, hit, bend, test. In Germany it is made one word in English it is the name of the French man who developed the test and in French it is essai de resiliance. I once had to discuss Charpy tests in French and sometimes English with a French man called Mr Charpy. Funny as hell.


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## SaparotRob (Jul 13, 2021)

I knew the "heute" part. Partial credit?

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## wuzak (Jul 13, 2021)

SaparotRob said:


> I knew the "heute" part. Partial credit?



I knew the "schwein" part.

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## pbehn (Jul 13, 2021)

SaparotRob said:


> I knew the "heute" part. Partial credit?


English is a Germanic language if you bear that in mind and consider letters were changed with time, "gestern" could be anything but if you know heute is "today" a wild guess could lead you to "yestern" the letters g and y are often substituted. Schwein of course is German but many Germans are unaware that swine is also used in English, and means the same.

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## Milosh (Jul 13, 2021)

English is a Heinz 57 language.

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## Glider (Jul 13, 2021)

Milosh said:


> English is a Heinz 57 language.


I admit to never having heard that description but its spot on


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## pbehn (Jul 13, 2021)

Glider said:


> I admit to never having heard that description but its spot on


It is officially a Germanic language but has easily more than 57 other languages used in it, bearing in mind there are at least 4 different types of French, and Latin words come from all sorts of routes.


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## Milosh (Jul 13, 2021)

Glider said:


> I admit to never having heard that description but its spot on


Usually applied to dogs for those not familiar with the expression.


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## soulezoo (Jul 13, 2021)

Milosh said:


> Usually applied to dogs for those not familiar with the expression.


or sometimes used on (hot) dogs.


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## swampyankee (Jul 13, 2021)

pbehn said:


> It is officially a Germanic language but has easily more than 57 other languages used in it, bearing in mind there are at least 4 different types of French, and Latin words come from all sorts of routes.


All languages borrow. English doesn't so much "borrow" as ambush and rob. (from James Davis Nicoll)

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## pbehn (Jul 13, 2021)

swampyankee said:


> All languages borrow. English doesn't so much "borrow" as ambush and rob. (from James Davis Nicoll)


The game is afoot, on the morrow I will sally forth to Helmsley Castle to confront my liege lord, Baron de Roos on this issue.

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## pbehn (Jul 13, 2021)

With regard to a topic a while ago, combat at high altitude I found this on the wiki page for the Ju 87

Testing revealed that at high altitude, even 2 g could cause death in an unpressurised cabin and without appropriate clothing. This new technology, along with special clothing and oxygen masks, was researched and tested. When the United States Army occupied the Junkers factory at Dessau on 21 April 1945, they were both impressed at and interested in the medical flight tests with the Ju 87.[31]​

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## 33k in the air (Jul 13, 2021)

pbehn said:


> . . . I will sally forth . . .



Don't call me Sally!

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## nuuumannn (Jul 13, 2021)

SaparotRob said:


> I wonder if there was a LW equivalent of the Groundhog.



Fw 187

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## SaparotRob (Jul 13, 2021)

Can you hijack threads with it or should we go with the Me-210?


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## GrauGeist (Jul 13, 2021)

Me210 was actually produced and hapless geschwaders got stuck with it and the pilots hated it.
It got passed off on the Hungarians, who actually liked it and did remarkably well with it.
Sound familiar?

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## pbehn (Jul 13, 2021)

GrauGeist said:


> Me210 was actually produced and hapless geschwaders got stuck with it and the pilots hated it.
> It got passed off on the Hungarians, who actually liked it and did remarkably well with it.
> Sound familiar?


Would moving a small piece of electrical equipment have helped at all?

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## SaparotRob (Jul 13, 2021)

Thanks pbehn!


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## GrauGeist (Jul 13, 2021)

pbehn said:


> Would moving a small piece of electrical equipment have helped at all?


I beleive it's entirely possible.
Perhaps the nose armor was an issue as well.

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## Vincenzo (Jul 13, 2021)

GrauGeist said:


> Me210 was actually produced and hapless geschwaders got stuck with it and the pilots hated it.
> It got passed off on the Hungarians, who actually liked it and did remarkably well with it.
> Sound familiar?


the hungarian Me 210 was not the same of the 210 originally put in service in the luftwaffe


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## pbehn (Jul 13, 2021)

GrauGeist said:


> I beleive it's entirely possible.
> Perhaps the nose armor was an issue as well.


Thankyou, it is now obvious that the Me210 could and would have won the BoB if only those fools could have seen it.

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## GrauGeist (Jul 13, 2021)

pbehn said:


> Thankyou, it is now obvious that the Me210 could and would have won the BoB if only those fools could have seen it.


Exactly!
It's shortcomings were so glaringly obvious, that even random people on an internet site could spot the issues 75 years later!

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## pbehn (Jul 13, 2021)

GrauGeist said:


> Exactly!
> It's shortcomings were so glaringly obvious, that even random people on an internet site could spot the issues 75 years later!


Pity those guys weren't as clued up as like wot we is.


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## nuuumannn (Jul 13, 2021)

pbehn said:


> Thankyou, it is now obvious that the Me210 could and would have won the BoB if only those fools could have seen it.



Ah, but let's not forget that if the RLM had chosen the Fw 187 instead of the Bf 110, the RAF would have been swept from the sky in 1940, AND the Luftwaffe would have had a MOSSIE KILLER! Nose armour? Who needs it! Heater? There's not even enough room in the cockpit for all its instruments!

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## pbehn (Jul 13, 2021)

nuuumannn said:


> Ah, but let's not forget that if the RLM had chosen the Fw 187 instead of the Bf 110, the RAF would have been swept from the sky in 1940, AND the Luftwaffe would have had a MOSSIE KILLER! Nose armour? Who needs it! Heater? There's not even enough room in the cockpit for all its instruments!


I think I can see some handy thread convergence here, great shout.

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## nuuumannn (Jul 13, 2021)

GrauGeist said:


> It's shortcomings were so glaringly obvious, that even random people on an internet site could spot the issues 75 years later!



The weird thing is, why the RLM and Messerschmitt couldn't work through the Me 210's (or the He 177's in fact) issues when, given our collective internet hive we could figure it out across the breadth of one Groundhog Thread!

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## GregP (Jul 13, 2021)

The Hungarian Me-210 had a Daschund in the nose that could run fore and aft when a change of CG was necessary. Only Black and Brown Daschunds could be used, however. It was an Austrian requirements forced on Messerschmitt, much as the pesky British ruined the otherwise flawless P-39, turning it into an urchin-snouted codpiece. 

As a result, the production of Me-210s was held up while more Black and Brown Daschunds were bred and raised to be center-of-gravity dogs. Otherwise, we'd have lost the war.

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## pbehn (Jul 13, 2021)

GregP said:


> The Hungarian Me-210 had a Daschund in the nose that could run fore and aft when a change of CG was necessary. Only Black and Brown Daschunds could be used, however. It was an Austrian requirements forced on Messerschmitt, much as the pesky British ruined the otherwise flawless P-39, turning it into an urchin-snouted codpiece.
> 
> As a result, the production of Me-210s was held up while more Black and Brown Daschunds were bred and raised to be center-of-gravity dogs. Otherwise, we'd have lost the war.


As a precaution the British developed the Blackburn Badger, it was as crap as all the other Blackburns but painted with a black and white nose to cause dachshund CoG issues and the infamous dachskrankheit in air crews.


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## nuuumannn (Jul 13, 2021)

GregP said:


> The Hungarian Me-210 had a Daschund in the nose that could run fore and aft when a change of CG was necessary.



The problem was, the Daschunds suffered from acute luxating patellas from all the running back and forth, an issue that affects the breed to this day. It shortened the combat utilization of the Me 210 and an interim had to be sought...


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## buffnut453 (Jul 13, 2021)

GregP said:


> The Hungarian Me-210 had a Daschund in the nose that could run fore and aft when a change of CG was necessary. Only Black and Brown Daschunds could be used, however. It was an Austrian requirements forced on Messerschmitt, much as the pesky British ruined the otherwise flawless P-39, turning it into an urchin-snouted codpiece.
> 
> As a result, the production of Me-210s was held up while more Black and Brown Daschunds were bred and raised to be center-of-gravity dogs. Otherwise, we'd have lost the war.



Gave you a bacon just for "urchin-snouted codpiece." Brilliant!

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## fubar57 (Jul 13, 2021)

Didn’t the RAF trial the Me210, made some unrealistic mods and then rudely cancel the order?

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## DerAdlerIstGelandet (Jul 13, 2021)

GregP said:


> The Hungarian Me-210 had a Daschund in the nose that could run fore and aft when a change of CG was necessary. Only Black and Brown Daschunds could be used, however. It was an Austrian requirements forced on Messerschmitt, much as the pesky British ruined the otherwise flawless P-39, turning it into an urchin-snouted codpiece.
> 
> As a result, the production of Me-210s was held up while more Black and Brown Daschunds were bred and raised to be center-of-gravity dogs. Otherwise, we'd have lost the war.



Best post ever.

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## pbehn (Jul 13, 2021)

fubar57 said:


> Didn’t the RAF trial the Me210, made some unrealistic mods and then rudely cancel the order?


I think they wanted it on lend lease, the sort of thing they did do. Mainly so they could write books about it later.


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## swampyankee (Jul 13, 2021)

pbehn said:


> Would moving a small piece of electrical equipment have helped at all?



Would throwing a toaster into the chief designer's bath count as "moving a small piece of electrical equipment?""

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## 33k in the air (Jul 13, 2021)

When, oh when, will we get a Brewster Buffalo Expert?

What is being done for the army P-39 needs to be done for the navy's F2A!

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## Greg Boeser (Jul 13, 2021)

Well, now that you mention it, I nominate Buffnut453!

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## buffnut453 (Jul 13, 2021)

Sorry to disappoint, fellas, but I'm far too pragmatic and level-headed to suggest that the poor old Buffalo was a good aircraft. It certainly doesn't deserve the reputation it has as a death trap that was shot down in droves. The fates conspired against it in British and US service to put it at a distinct operational and tactical disadvantage when thrown into combat...but as a fighter aircraft it was mediocre at best. 

You may now return to your regularly-scheduled programming which, rather like the TV, seems mostly to consist of rather tedious repeats.

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## 33k in the air (Jul 13, 2021)

buffnut453 said:


> Sorry to disappoint, fellas, but I'm far too pragmatic and level-headed to suggest that the poor old Buffalo was a good aircraft. It certainly doesn't deserve the reputation it has as a death trap that was shot down in droves. The fates conspired against it in British and US service to put it at a distinct operational and tactical disadvantage when thrown into combat...but as a fighter aircraft it was mediocre at best.



Sometimes I almost feel sorry for the Buffalo. You're right in that it is not as terrible as often made out. But unfortunately it's a rather tubby, unattractive aircraft; it if looked cooler it'd probably be rated at least a little higher.

The Finns got some good use out of it at any rate.

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## SaparotRob (Jul 14, 2021)

The Buffalo looks better with yellow wings.


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## buffnut453 (Jul 14, 2021)

33k in the air said:


> Sometimes I almost feel sorry for the Buffalo. You're right in that it is not as terrible as often made out. But unfortunately it's a rather tubby, unattractive aircraft; it if looked cooler it'd probably be rated at least a little higher.
> 
> The Finns got some good use out of it at any rate.



Well, actually, despite its poor performance in theatres other than Finland, the poor old Buffalo still achieved an overall kill-to-loss ratio of 26:1 (ok...claim to loss, but you get my drift). Therefore, statistically speaking, we should have scrapped all the Hurricanes, Spitfires, P-47s, and P-51s and just pumped out as many Buffalos as possible. 

There....does that mean I can now be admitted to the Worshipful Company of Groundhogs?

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## SaparotRob (Jul 14, 2021)

You might just be the Grand Marmota Monax Maximus.

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## XBe02Drvr (Jul 14, 2021)

buffnut453 said:


> There....does that mean I can now be admitted to the Worshipful Company of Groundhogs?


Weren't you born into it?

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## Peter Gunn (Jul 14, 2021)

33k in the air said:


> *SNIP*





33k in the air said:


> But unfortunately it's a rather tubby, unattractive aircraft; it if looked cooler it'd probably be rated at least a little higher.
> 
> *SNIP*


Whoa whoa whoa here... just whoa...

Them's fightin' words sonny...

Eye of the beholder remember.  

*EDIT*

Just remember, you're talking to a guy that thinks French pre-dreadnoughts are cool.

Why yes, I do see a therapist once a week, why do you ask?

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## SaparotRob (Jul 14, 2021)

I asked about any P-39 v. Buffalo encounters during the Continuation War. The response I got was that the Finnish did score against the P-39. To quote an old Ken-L-Ration dog food commercial: My dog's better than your dog!

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## SaparotRob (Jul 14, 2021)

French pre-dreadnoughts ARE cool. Check out Drachinel's video on French Pre-dreadnoughts; When Hotels Go To War.

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## buffnut453 (Jul 14, 2021)

SaparotRob said:


> You might just be the Grand Marmota Monax Maximus.



I think I'll add that to my business cards. Sounds awesome. 

Next question...can I wear the fez?

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## Milosh (Jul 14, 2021)

SaparotRob said:


> French pre-dreadnoughts ARE cool. Check out Drachinel's video on French Pre-dreadnoughts; When Hotels Go To War.


A good site for BBs photos is Vintage photographs of battleships, battlecruisers and cruisers.

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## SaparotRob (Jul 14, 2021)

Great link!

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## SaparotRob (Jul 14, 2021)

buffnut453 said:


> I think I'll add that to my business cards. Sounds awesome.
> 
> Next question...can I wear the fez?
> 
> View attachment 632195


I think I still have one in my car! I was toying with wearing it because I had a friend who wore a beret. I can be as pompous as the next guy.


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## Peter Gunn (Jul 14, 2021)

Milosh said:


> A good site for BBs photos is Vintage photographs of battleships, battlecruisers and cruisers.





SaparotRob said:


> French pre-dreadnoughts ARE cool. Check out Drachinel's video on French Pre-dreadnoughts; When Hotels Go To War.


Waaaaaaaaaay ahead of both of you BUT, thanks for posting those anyway.

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## Milosh (Jul 14, 2021)

Peter Gunn said:


> Waaaaaaaaaay ahead of both of you BUT, thanks for posting those anyway.


But many others might not be.

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## Peter Gunn (Jul 14, 2021)

Milosh said:


> But many others might not be.


Hence the latter half of my post.

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## GrauGeist (Jul 14, 2021)

buffnut453 said:


> I think I'll add that to my business cards. Sounds awesome.
> 
> Next question...can I wear the fez?
> 
> View attachment 632195


Why not wear a Teddy Roosevelt slouch hat and round-rimmed glasses?
That way you can go around saying "bully! bully!" to everything.

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## SaparotRob (Jul 14, 2021)

I tried it but the neighbors complained.

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## 33k in the air (Jul 14, 2021)

SaparotRob said:


> French pre-dreadnoughts ARE cool. Check out Drachinel's video on French Pre-dreadnoughts; When Hotels Go To War.



First thing I thought of when French pre-dreadnoughts were mentioned!

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## P-39 Expert (Jul 14, 2021)

Shortround6 said:


> You haven't proven many or indeed any of them.
> 
> _Saying_ they are wrong is not _proving_ they are wrong.
> 
> ...


First, nobody can prove British intent. I can't prove that the British intended to make the P-400 too heavy to make the performance guarantee. You can't prove that they didn't. But they certainly knew that a 7850lb P-400 with a 1150hp engine couldn't go 400mph, especially when their contemporary 6600lb Spitfire V would only go 371mph with a more powerful engine. And Bell knew that the P-400 couldn't make the guarantee, certainly not at 7850lbs. Who's fooling who? A P-400 tested in the US did go 371mph albeit at a lower altitude. 

The IFF was useless in 1942 NG because there was no accurate radar until fall. The British DID order it but once the P-400s were diverted to NG the IFF would have been removed. To save the weight.

The gas cockpit heater WAS useless. Specified on the Bell Model 14 (P-400 and P-39D-1/2 EXPORT models) it caused radio static when in use and had an indicator on the instrument panel for when it overheated. Very effective ducted air system used on all the other P-39 models (D/F/K/L/M/N/Q) didn't cause radio static and didn't overheat. 

The British rushed their 20mm cannon into production because even eight 30calMGs were proven ineffective in the BoB. No AAF or USN fighters used 30s in WWII except the P-39. They were redundant on a plane with cannon and heavy MG centerline armament. And it's effective range was only 200yds. Sure there are mistakes in AHT, as with any reference. But you haven't proven that the EFFECTIVE range was any farther.


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## pbehn (Jul 14, 2021)

P-39 Expert said:


> First, nobody can prove British intent. I can't prove that the British intended to make the P-400 too heavy to make the performance guarantee. You can't prove that they didn't.


To prove any "intent" the British would have to impose conditions on Bell that they didn't impose on anyone else either British or American. That is easily settled, all needed self sealing tanks, armour and IFF. Before any P-39 came to UK the British were fitting all of that to Hurricanes, as well as 12 x 0.303mgs or 4 x 20mm. They were also fitting cannon to Spitfires in 1940, how many times can this be gone over? The Bf 109 and Fw 190 retained rifle calibre guns until the end of the war BTW.


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## P-39 Expert (Jul 14, 2021)

pbehn said:


> To prove any "intent" the British would have to impose conditions on Bell that they didn't impose on anyone else either British or American. That is easily settled, all needed self sealing tanks, armour and IFF. Before any P-39 came to UK the British were fitting all of that to Hurricanes, as well as 12 x 0.303mgs or 4 x 20mm. They were also fitting cannon to Spitfires in 1940, how many times can this be gone over? The Bf 109 and Fw 190 retained rifle calibre guns until the end of the war BTW.


How many times are you going to twist this around? It's not that they needed armor, it's HOW MUCH ARMOR. Yes the British were still using 30calMGs after the BoB, but the AAF WAS NOT. Except for the P-39. The British were using a few 20mm cannon in the BoB, but VERY VERY FEW on an experimental basis. They were unreliable and didn't hold enough ammunition at that stage of their development. The British did need IFF but the AAF DID NOT in NG in '42.

You are the one that continues to troll. If you don't like it, stop trolling.


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## pbehn (Jul 14, 2021)

P-39 Expert said:


> How many times are you going to twist this around? It's not that they needed armor, it's HOW MUCH ARMOR. Yes the British were still using 30calMGs, but the


How much armour is a pretty puzzle, as much as the Russians used, I should wager.


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## pbehn (Jul 14, 2021)

P-39 Expert said:


> How many times are you going to twist this around? It's not that they needed armor, it's HOW MUCH ARMOR. Yes the British were still using 30calMGs after the BoB, but the AAF WAS NOT. Except for the P-39. The British were using a few 20mm cannon in the BoB, but VERY VERY FEW on an experimental basis. They were unreliable and didn't hold enough ammunition at that stage of their development. The British did need IFF but the AAF DID NOT in NG in '42.
> 
> You are the one that continues to troll. If you don't like it, stop trolling.


Yes the British were experimenting in the BoB with cannon, that was a year before the P-39 arrived in UK. You have repeatedly quoted the performance of your 1942 super light P-39 as being useful in Europe, even suggesting it could be used as a bomber escort.


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## GrauGeist (Jul 14, 2021)

P-39 Expert said:


> The IFF was useless in 1942 NG because there was no accurate radar until fall. The British DID order it but once the P-400s were diverted to NG the IFF would have been removed. To save the weight.


There was an SCR-268 station on Guadalcanal by summer of '42.


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## Glider (Jul 14, 2021)

P-39 Expert said:


> How many times are you going to twist this around? It's not that they needed armor, it's HOW MUCH ARMOR. Yes the British were still using 30calMGs after the BoB, but the AAF WAS NOT. Except for the P-39. The British were using a few 20mm cannon in the BoB, but VERY VERY FEW on an experimental basis. They were unreliable and didn't hold enough ammunition at that stage of their development. The British did need IFF but the AAF DID NOT in NG in '42.
> 
> You are the one that continues to troll. If you don't like it, stop trolling.


I think you are mixing a little bit of truth but then extrapolating it to prove a point using a falsehood

Let me explain
_Yes the British were still using 30calMGs after the BoB, but the AAF WAS NOT. Except for the P-39. The British were using a few 20mm cannon in the BoB, but VERY VERY FEW on an experimental basis. They were unreliable and didn't hold enough ammunition at that stage of their development _

This is of course absolutely true but irrelevant in the P39 saga. When the British first equipped a squadron with the P39 in Mid 1941 the Spitfire IIb and Vb had been in service for some months with a reliable 20mm and the Vc was entering production and service which had both a reliable 20mm and more ammunition. Something I don't think you have ever acknowledged. The Hurricane IIc was also entering production and service with 4 x 20mm

_First, nobody can prove British intent. I can't prove that the British intended to make the P-400 too heavy to make the performance guarantee_. 
Actually its almost impossible to prove that something that didn't happen. But its what isn't there that proves that the British never intended to ruin the P39 so it could fail the performance guarantee. Bell had a huge amount riding on the P39 and if they had even suspected that things were being done to effectively sabotage its performance, they would have been screaming from the rooftops. The papers would have been full of it and politicians who love this kind of thing would have been causing merry hell. 

So when you say _I can't prove that the British intended to make the P-400 too heavy to make the performance guarantee_. Your wrong, you can, we are just asking you to do it instead of stating a statement without any evidence.

The steps are simple for an expert such as yourself 
a) Find any demand that the UK made that wasn't already being installed on their own aircraft
b) Find any complaint from Bell that demands were excessive and designed to ruin the aircrafts performance
c) Find any legal proceedings along these lines
d) Find any paper or politician sounding off about this scandal 

We await your response with interest

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## Shortround6 (Jul 14, 2021)

Supposed to be wrecks of P-40s destroyed at Pearl Harbor which I believe was Dec 7th 1941.
P-40s with nose guns used .30 machine guns in the wings.
The BoB was over 1 year earlier.

"Y_es the British were still using 30calMGs after the BoB, but the *AAF WAS NOT*. Except for the P-39."_

Obviously false.
The AAF may not have been installing .30 cal guns in new fighters but they were certainly using them well after the BoB.
BTW the last P-40C was delivered to the AAF, complete with four .30 cal wing guns, In April of 1941.

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## pbehn (Jul 14, 2021)

My point was very simple, dates and details actually obscure the point. All sides were trying to increase armament in all sorts of ways, you cant make a case for any request about armament being a conspiracy against the P-39 by the British and you cant make a case for rifle calibre ammunition being so useless it shouldnt have been fitted. Fitting of cannon to British aircraft reduced top speed, the cannon were fitted and the top speed reduced because cannon were more important than absolute top speed. If the thing had done 400 MPH at the start it wouldnt have mattered.


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## wuzak (Jul 14, 2021)

P-39 Expert said:


> No AAF or USN fighters used 30s in WWII except the P-39. They were redundant on a plane with cannon and heavy MG



As pointed out by others, the P-40 did.

Also note that the Mustang I supplied to the RAF had 4 x 0.50" and 4 x 0.30" machine guns.

It shows that the 3 gun armament was deemed insufficient by the Western Allies. Even the 4 gun P-51A and P-51B were considered under-gunned, hence the 6 gun P-51D.

The P-39 couldn't fit the 0.50" inside the wing, from what I understand. So the only option was 0.30" mgs (until they stuck on the gondolas).


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## pbehn (Jul 14, 2021)

According to this the first P-40s to arrive in UK had two x 0.5" synchronised guns. The Pesky British seeing another chance to have no planes in Africa asked for 4 x 303s to be put in a redesigned wing. Mr Curtis said "you aint getting outta this contract" and produced them, Uncle Sam said "thats a mighty fine pair of wings I see there, can I have some", so that became the P-40G, Uncle Sam kept some and sent some to his friend Joe. 4 x 0.5" wing guns became the standard armament.


cant copy from the link, 5th paragraph down 





Curtiss P-40 Tomahawk


Page details technical specifications, development, and operational history of the Curtiss P-40 Tomahawk including pictures.



www.militaryfactory.com

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## Greg Boeser (Jul 14, 2021)

This nonsense about the AAF not using fighters with .30s, it has to stop. P-40Bs were deployed to Hawaii, the Philippines, and the Canal Zone pre war. In the Philippines were also P-35As. Also stationed in Hawaii were P-36As and P-26s. P-36s were also stationed in Alaska. This does not include the multitude of other fighters based in CONUS. The 23rd Fighter Group, in July 1942, absorbed the remaining H-81A-3s originally equipping the AVG. (OK, you can argue that the ex-AVG planes were armed with .303s and 7.92mm, but the point is they continued to serve as combat aircraft well into 1943.) It is true that Curtiss was already responding to armament upgrades prior to Pearl Harbor, and the USAAF did not order any more fighter aircraft with .30s except the P-39, but remember, two P-39 equipped fighter groups destined for North Africa were re-equipped with Spitfire VBs in late 1942. Does using .303s exempt them from the charge that the USAAF never used .30s except in the P-39? These groups would eventually receive Spitfire IXs as replacements before converting to P-51Bs in 1944. So rifle caliber weapons continued to serve in USAAF fighters other than the P-39 until fairly late in the war. P-39s were a stop gap. Nobody wanted them (except the Russians.) They continued to serve honorably until they could be replaced by more capable fighters as these became available.

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## pbehn (Jul 14, 2021)

Greg Boeser said:


> This nonsense about the AAF not using fighters with .30s, it has to stop.


If there was a way to stop repeated nonsense it wouldnt be a groundhog thread.

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## Greg Boeser (Jul 14, 2021)

Dang, I forgot about the venerable 4th Fighter Group (ex-Eagle Squadrons) in England that transferred wholesale from the RAF to the USAAF and brought their Spitfires with them.

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## pbehn (Jul 14, 2021)

Greg Boeser said:


> Dang, I forgot about the venerable 4th Fighter Group (ex-Eagle Squadrons) in England that transferred wholesale from the RAF to the USAAF and brought their Spitfires with them.


It is a typical groundhog argument. The USA wasnt in the war until 13 months after the BoB ended so what is "using". Had every US aircraft been switched to 0.5s? Obviously not. Was a plane shipped new and used after Oct 1940 with 0.3mgs? Yes. But many or most were changing to 0.5" which proves Uncle Sam was trying to get out of contracts more than the Brits, or maybe Uncle Sam like everyone else just wanted more firepower and no other supplier had an issue.


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## Greg Boeser (Jul 14, 2021)

I'm not sure what he's trying to get at. He seems to be trying to say that the P-39 was unfairly saddled with inadequate armament. But the RAF continued to use rifle caliber guns on their fighters throughout the war. Not _all _fighters, but a substantial portion of them. And if we look at 1941, when the P-39 is introduced, nearly all operational fighters in the RAF rely on a mix of cannon and rifle caliber mgs or large batteries of .303 caliber mgs. His argument that the RAF tanked the performance of the P-39 by demanding that it have similar firepower to its existing stable of fighters is absurd.

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## pbehn (Jul 14, 2021)

Greg Boeser said:


> I'm not sure what he's trying to get at. He seems to be trying to say that the P-39 was unfairly saddled with inadequate armament. But the RAF continued to use rifle caliber guns on their fighters throughout the war. Not _all _fighters, but a substantial portion of them. And if we look at 1941, when the P-39 is introduced, nearly all operational fighters in the RAF rely on a mix of cannon and rifle caliber mgs or large batteries of .303 caliber mgs. His argument that the RAF tanked the performance of the P-39 by demanding that it have similar firepower to its existing stable of fighters is absurd.


There are two arguments. 
1 that the P-39N when lightened could be useful in the far east, others have answered that in detail.
2 Once argument 1 is accepted the requests of the British are said to be unreasonable and the P-39 could have been useful in Europe in 1941-42 and the British should have kept it.

The British wanted 4 cannon on all fighters like the Mustang, Hurricane II Typhoon Tempest.
The Spitfire was the exception because it was always the high altitude fighter, the weight of 4 cannon affected performance at high altitude and it was difficult to keep them warm. They kept the extra 4 x 303 because they were better than nothing, capable of taking down an enemy fighter just not as capable as others. In firepower the two cannon were about the same as 6 x 0.5" so it was a bonus not desperation. When the UK became awash with 0.5" ammunition the Spitfire got 2 x 0.5" which gave a trajectory closer to that of the cannon.

Armour was fitted to the Spitfire first in front of the pilot, then behind, until the possibility of France falling came into peoples minds it hadnt been thought needed because only bombers would be coming to UK.

There was a war on, without all this stuff you would just be killing your own pilots, which are more valuable than the plane itself. If you sell weapons to someone you cant start telling him what sort of fight to use it in, or what he needs, when he has been in the fight for 2 years.

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## Shortround6 (Jul 14, 2021)

In reverse order. 



P-39 Expert said:


> The British rushed their 20mm cannon into production because even eight 30calMGs were proven ineffective in the BoB. No AAF or USN fighters used 30s in WWII except the P-39. They were redundant on a plane with cannon and heavy MG centerline armament. And it's effective range was only 200yds. Sure there are mistakes in AHT, as with any reference. But you haven't proven that the EFFECTIVE range was any farther.


Oh, boy. 
The British had been rushing the 20mm Hispano gun into production since 1938, if not earlier. 
The British MARC company deed of partnership was registered on Jan 11th 1938. 
The title deeds for the for the plots of land for the buildings were recorded in June of 1938 and the first prototype guns were being built and tested started in Jan 1939. 
At the official opening of the factory in Jan 1939 the Duke of Gloucester fired the first British HS-404 cannon. 
British were planning on putting 20mm cannon into existing designs and not wait for new designs in the Spring of 1940, well before the BoB. 
Yes it took a while to get the numbers desired/needed. 

Hundreds of German aircraft destroyed during the BoB might show a different result than "proven ineffective" this has been gone over many times. Likes the "ineffectiveness" of The Japanese 7.7mm (.303) guns. 
As for the "effective range of the .30 cal or .303. How about you park you car out in field and let me shoot 40-60 rounds at it with a 30-06 or .303 rifle at 400yds (double the distance at which the .30 cal become ineffective) and then tell me how ineffective they are. 



Switching the goal post on the heater???
Did the British ask for it or take what was offered? You claim the British asked for it. Was the new heat system offered to the French? Did the British change it back? 


P-39 Expert said:


> The IFF was useless in 1942 NG because there was no accurate radar until fall. The British DID order it but once the P-400s were diverted to NG the IFF would have been removed. To save the weight.


Another switcheroo. You claimed the British added unneeded weight to get out of the contract. IFF was needed in 1940-41 and 42 over Britain and in the contested space over the channel. 


P-39 Expert said:


> First, nobody can prove British intent. I can't prove that the British intended to make the P-400 too heavy to make the performance guarantee. You can't prove that they didn't. But they certainly knew that a 7850lb P-400 with a 1150hp engine couldn't go 400mph, especially when their contemporary 6600lb Spitfire V would only go 371mph with a more powerful engine. And Bell knew that the P-400 couldn't make the guarantee, certainly not at 7850lbs. Who's fooling who? A P-400 tested in the US did go 371mph albeit at a lower altitude.


 changing your tune? You claimed the British made the P-400 too heavy so as to get out of the contract, Now you are saying you can't *prove it*. But you still want us to believe it. 

As for the British KNOWING that the 7850lb P-400 with 1150hp engine couldn't go 400mph? 
If they knew that they should have told North American to quit fooling around with the NA 73 and just build P-40s. 
British tested an 8600lb Mustang I at 370mph with an 1150 hp (?)engine. 
Aircobra tested in England was 800lb lighter, used the same engine and was 15mph slower. 

Power vs drag determines speed, not power vs weight. 
Expecting a smaller, more streamline plane, even if heavier, to make a higher top speed than a larger/older/higher drag airplane was not unreasonable. Difficult but not impossible. 
Bell flubbed it, big time.

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## nuuumannn (Jul 14, 2021)

It's worth noting that one of the main reasons why the RAF rejected the Airacobra was compass deviation when its guns were fired, at rates as high as 160 degrees, which rendered it completely useless. This was clearly unacceptable to the British, but eventually, a fix was found, although by that time the decision had been made to replace the Airacobras in service with Spitfire Vs, which had better performance at any rate. Did the US forces ever record this as an issue with the P-39?

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## Shortround6 (Jul 14, 2021)

For the Americans and British the BoB didn't "*prove*" much of anything.
The P-40D with four wing mounted .50s was officially ordered in Sept of 1940.
The idea of sticking the -39 engine in the P-40 airframe instead of building the P-46 was several months earlier.

As far as the "unreasonable" armament requirement goes. The Original Mustang Is carried.
Two fuselage .50 cal guns..................................128lbs
Two wing .50 cal guns..........................................128lbs
four .303 wing guns ................................................86lbs
400 rounds for the
fuselage .50s..............................................................100lbs
612 rounds for the
Wing .50s....................................................................152lbs
3492 rounds for
the wing .303............................................................227lbs.

total, guns and ammo..........................................821lbs

Just think of the speed and climb of the Mustang I if the useless wing guns had been deleted 

Edit, BTW the Mustang I used as Stewart-Warner (where have we heard that name before  )fuel heater to warm the wing gun bays.

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## Shortround6 (Jul 14, 2021)

nuuumannn said:


> It's worth noting that one of the main reasons why the RAF rejected the Airacobra was compass deviation when its guns were fired, at rates as high as 160 degrees, which rendered it completely useless. This was clearly unacceptable to the British, but eventually, a fix was found, although by that time the decision had been made to replace the Airacobras in service with Spitfire Vs, which had better performance at any rate. Did the US forces ever record this as an issue with the P-39?


Don't know.
Larry Bell's solution to the low performance of the P-39/P-400 was to get rid of such frippery as the compass. Likewise all blind flying instruments.

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## nuuumannn (Jul 14, 2021)

Shortround6 said:


> Likewise all blind flying instruments.



Curtiss did in an attempt to make the P-40 quicker to manufacture the firm deleted the vacuum pump, which meant vacuum-driven instrumentation was removed.


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## Shortround6 (Jul 14, 2021)

The early P-40Ns were stripped of quite a bit of stuff, as I am sure you know, in an attempt to significantly lighten the airplane.
Most of the stuff was put back in by the service squadrons.
The extra performance wasn't worth the loss in operational capability.

The "stripper" P-39 was pretty much down to an airspeed indicator, an altimeter and few engine gauges (to keep from cooking the the engine) also the oxygen system was removed. Pretty much anything that wasn't needed to fly at 5,000ft.

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## nuuumannn (Jul 14, 2021)

Shortround6 said:


> The extra performance wasn't worth the loss in operational capability.



From what I've read about the P-40s the modifications did little to improve performance in the 'N model. Some non-structural parts were replaced with 'plastic' parts, such as the map case, etc, to save weight.

I can vaguely remember hearing about an incident where P-40s escorting B-24s in either Papua or the Solomons, flew into a mountain when they got lost in fog because they had no instrument flying capability.

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## nuuumannn (Jul 14, 2021)

Shortround6 said:


> The "stripper" P-39 was pretty much down to an airspeed indicator, an altimeter and few engine gauges (to keep from cooking the the engine) also the oxygen system.



Did it improve the type's performance at all?


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## Shortround6 (Jul 14, 2021)

Yes, The list is upthread somewhere but here it is again.

This was serial number 41-38291, a P-39D-1. first in standard configuration and then modified.
Removal of the four wing guns and supporting accessories, all of the gear box armor plate, the oxygen system, all radio equipment, all instruments except the altimeter, the airspeed indicator, engine manifold pressure gage, tachometer, temperature and pressure gauges; all tools and fixed equipment not essential for flight at 5,000ft, all ballast and four of the eight self-sealing fuel cells. This saved 1287lbs. On page 159 of "Cobra!" by Birch Mathews. 
The only performance figures given are for time to 5,000ft, radius of turn and stalling speed. Time to climb 5,000ft dropped from 2 min 34 sec to 1 min 54 sec.

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## nuuumannn (Jul 14, 2021)

Shortround6 said:


> Yes, The list is upthread somewhere but here it is again.



Thanks for that (I don't wanna go searching through the entire thread). So, what was learned from it? Did these changes lead to improvements that were applied to the type on the production line and in service?


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## buffnut453 (Jul 14, 2021)

Glider said:


> We await your response with interest



Methinks it'll be a long wait. Direct questions haven't been answered with anything other than opinion....and even then, they're ignored more than answered.

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## buffnut453 (Jul 14, 2021)

P-39 Expert said:


> The gas cockpit heater WAS useless. Specified on the Bell Model 14 (P-400 and P-39D-1/2 EXPORT models) it caused radio static when in use and had an indicator on the instrument panel for when it overheated. Very effective ducted air system used on all the other P-39 models (D/F/K/L/M/N/Q) didn't cause radio static and didn't overheat.



And it was also specified in the Bell Model 13, P-39C which suggests the British did NOT specify the gas heater. This has been raised several times but you keep ignoring this fact.

If the gas heater was useless, then it's down to Bell who included it as standard equipment in the Model 13. The British would simply have ensured cockpit heating was provided...it was down to Bell to ensure the heating system worked correctly.


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## Glider (Jul 15, 2021)

buffnut453 said:


> Methinks it'll be a long wait. Direct questions haven't been answered with anything other than opinion....and even then, they're ignored more than answered.


I should have ended it ' We await your response with interest, but not much anticipation

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## GrauGeist (Jul 15, 2021)

Glider said:


> I should have ended it ' We await your response with interest, but not much anticipation


It was a great post, but I would have concluded with:
"I don't expect an informed reply."

But then again, I'm not known for my diplomacy...

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## Juha3 (Jul 15, 2021)

P-39 Expert said:


> .... The IFF was useless in 1942 NG because there was no accurate radar until fall. The British DID order it but once the P-400s were diverted to NG the IFF would have been removed. To save the weight...


There was an operational radar since late March 1942 at Port Moresby. It performed poorly, mainly because inadequate training of its staff, but the fact that there was an operational radar meant that a/c operating in the area needed IFF. More info in this message by late Parsifal SHOULD the P39 have been able to handle the Zero? Was it training or performance?

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## P-39 Expert (Jul 15, 2021)

Shortround6 said:


> Yes, The list is upthread somewhere but here it is again.
> 
> This was serial number 41-38291, a P-39D-1. first in standard configuration and then modified.
> Removal of the four wing guns and supporting accessories, all of the gear box armor plate, the oxygen system, all radio equipment, all instruments except the altimeter, the airspeed indicator, engine manifold pressure gage, tachometer, temperature and pressure gauges; all tools and fixed equipment not essential for flight at 5,000ft, all ballast and four of the eight self-sealing fuel cells. This saved 1287lbs. On page 159 of "Cobra!" by Birch Mathews.
> The only performance figures given are for time to 5,000ft, radius of turn and stalling speed. Time to climb 5,000ft dropped from 2 min 34 sec to 1 min 54 sec.


This was a one-off example. I have shown numerous times how a properly equipped 1942 P-39 would have weighed 7150 lbs. 

Bell did show how P-39 weight could be reduced by 1000lbs in May 1943. Details were not provided in the book.


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## P-39 Expert (Jul 15, 2021)

One last time, no 30calMGs were used on any AAF/USN P-38E/F/G/H/J/L, P-40D/E/FK/L/M/N, P-47, P-51A/B/C/D, F4F3/4, F4U1/4, F6F, F7F, F8F. None. 100,000 planes, how many used 30cals? None. Except the P-39. 

Exactly how many P-40B/Cs actually saw combat with the AAF? How many P-35s? A very insignificant amount.


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## pbehn (Jul 15, 2021)

P-39 Expert said:


> One last time, no 30calMGs were used on any AAF/USN P-38E/F/G/H/J/L, P-40D/E/FK/L/M/N, P-47, P-51A/B/C/D, F4F3/4, F4U1/4, F6F, F7F, F8F. None. 100,000 planes, how many used 30cals? None. Except the P-39.
> 
> Exactly how many P-40B/Cs actually saw combat with the AAF? How many P-35s? A very insignificant amount.


So they used something heavier? So what is your point? How can you claim the British wanting things that increased weight was perfidy when the US was doing exactly the same. BTW you are doing that thing again where your "never" becomes not "often". Of those 100,000 the P-39s used by the USA as a weapon was also an insignificant amount.


P-39 Expert said:


> This was a one-off example. I have shown numerous times how a properly equipped 1942 P-39 would have weighed 7150 lbs.


And how does that look against a P-38, P-47, Mustang I, Spitfire IX, Typhoon? Would you cross the Channel to take on an Fw 190 with it?

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## pbehn (Jul 15, 2021)

Shortround6 said:


> As for the British KNOWING that the 7850lb P-400 with 1150hp engine couldn't go 400mph?
> If they knew that they should have told North American to quit fooling around with the NA 73 and just build P-40s.
> British tested an 8600lb Mustang I at 370mph with an 1150 hp (?)engine.
> Aircobra tested in England was 800lb lighter, used the same engine and was 15mph slower.
> ...


I would say it would be perfectly reasonable. The Mustang I defied what was known when the Spitfire and Hurricane were designed and ordered. 
The UK had ordered its first jet in 1939 and started testing it in April 1941, it flew in May 1941 doing 350MPH on its first flight which completely defied what was known by most. With advances in aerodynamics, a revolutionary mid engine design, much lighter than a Mustang I could easily be believed to be faster and close to 400MPH.


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## Juha3 (Jul 15, 2021)

P-39 Expert said:


> One last time, no 30calMGs were used on any AAF/USN P-38E/F/G/H/J/L, P-40D/E/FK/L/M/N, P-47, P-51A/B/C/D, F4F3/4, F4U1/4, F6F, F7F, F8F. None. 100,000 planes, how many used 30cals? None. Except the P-39.
> 
> Exactly how many P-40B/Cs actually saw combat with the AAF? How many P-35s? A very insignificant amount.


Your original claim was "_Yes the British were still using 30calMGs after the BoB, but the AAF WAS NOT_." Again, when shown that you were wrong, your changed your claim, as you always do. 1/5 of USAAC fighters in Philippines on 7 Dec 1941 were P-40Bs (18) and 1/5 P-35s (18), and there were definitely P-40Bs on Oahu.

And most of the great aces of the WWII acknowledged that surest way to make a kill was open fire at close range, 200 yds was a good range to make a kill in early 40s. And on effectiveness of the .303, on 6 Jan 1940 Sarvanto shot down six Soviet DB-3Fs, these had armour and self-sealing fuel tanks, in five minutes while flying in Fokker D.XXI, 4 7.7 mm Brownings. And those six were not only claims, all six wrecks were found and nowadays we know from Russian documents that only one of 8 DB-3Fs of that formation returned and 7 were shot down the 7th by Sovelius. Sarvanto was exceptionally good shot and as Finns were trained opened fire at close range and probably all or three of his mgs were loaded with Italian APIs, the 4th might have been loaded with trackers. The downside of the close range tactic was that Sarvanto's plane was hit 23 times during the engagemant.

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## Shortround6 (Jul 15, 2021)

Strangely enough the British wound up using a convergence distance of 250 yds for their .303s, 50 yds beyond the effective range?
Earlier they had set up the guns to converge at 350yds 

The American .30-06 was one of the two most powerful rifle caliber machine gun cartridges used in WW II. It was around 18% more powerful than the British .303 or the Japanese 7.7mm.
It had about 10% more velocity for shorter time of flight.
Not a lot but to say that the US .30 was useless when other countries achieved so much with weaker cartridges and slower firing/rate of fire guns (Japanese) seems to fly in the face of common sense.
There was also a supply issue, in 1940-41-42 there weren't enough .50 cal guns for everybody that wanted them. Remember that supply allocations were often made months if not over a year before actual construction/deployment. 
A number of US bombers went into service in 1940-41 and 42 using at least a few .30 cal guns. 

The US may very well have been specifying too many guns or too heavy a weight of guns/ammo for good performing aircraft. The P-40D & E were a classic example.
However in 1940 NOBODY had much experience with the US .50 cal in combat.
First combat Victory by a U.S. built fighter in the ETO was by a Martlet on Christmas day 1940, well after the daylight portion of the BoB was over. 
Any and all advantages of the .50 cal gun and ammo were purely theoretical up to that point, except, _perhaps _for a few .50 cal guns that might have made it to China?

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## Peter Gunn (Jul 15, 2021)

P-39 Expert said:


> One last time, no 30calMGs were used on any AAF/USN P-38E/F/G/H/J/L, P-40D/E/FK/L/M/N, P-47, P-51A/B/C/D, F4F3/4, F4U1/4, F6F, F7F, F8F. None. 100,000 planes, how many used 30cals? None. Except the P-39.
> 
> Exactly how many P-40B/Cs actually saw combat with the AAF? How many P-35s? A very insignificant amount.


Uh... what?

I see you cherry pick around the P-40 and P-51 marques that were armed with .30's which surprises me not in the least.

Not to mention that the original F4U design used .30's as did the F2A.

As for the Airacobra, keep the wing guns, ditch the dumb cannon and replace it and the two nose guns with .30's and you'd have a 7 gun fighter with all the same caliber weapons (read same trajectory/ballistics) and a sh!t load of ammunition and turn it loose against the IJN/IJA.

And on another note, to say that IFF isn't needed is down.right.stupid.

I'm pretty sure Bifff (with 3 'f's) has already given you the reason you don't want to delete the IFF, but hey, why listen to an experienced fighter pilot amiright? Ah yes, he didn't fly P-39's and he's just Joe Pilot anyway so we can discount his opine on that.

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## Shortround6 (Jul 15, 2021)

P-39 Expert said:


> This was a one-off example. I have shown numerous times how a properly equipped 1942 P-39 would have weighed 7150 lbs.


Lets try again.
P-39K at 6663lbs tactical empty from the weight chart in the manual.
Take out 100lbs worth of .30 cal guns or even add another 20lbs for "extras" 
take out 100lbs of armor. leaving you with what the P-39C had. 
take out 45lbs for IFF, that seems to be the highest figure. 
you are down to just under 6400lbs
now add 720lbs of fuel. 
*OOPS*, 7120lbs with *NO AMMO*. 
That is a 1942 P-39. 
No P-39M or N made it into combat in 1942. 
You want to argue about P-40B&Cs and _when they were used_? 
You have to take it on the other end. 



P-39 Expert said:


> Bell did show how P-39 weight could be reduced by 1000lbs in May 1943. Details were not provided in the book.


I wonder why? 
Again, look at the P-40N-1 to see what they did. And they used aluminum radiators/oil coolers and magnesium wheels in addition to restricting armament and ammo.

That ONE OFF saved 1287lbs. There simply isn't enough stuff to take back out of the plane to save 1000lbs without severely compromising operational use. 
All but a few hundred pounds went back into the P-40N-1s once they got to the operational squadrons. Stupid squadron commanders?


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## BiffF15 (Jul 15, 2021)

Gents,

FYI this round and round regarding the P39 by the Expert has been going on since March, 2018. That’s 3 years, 4 months. If this was a war front, I would describe it as a WW1 trench front, concertina wire tacked to fence posts, blown apart in places, trees with no leaves, brick remains of buildings, destroyed in the melee with scattered remains of soldiers killed during gas attacks. And there is absolutely nothing to show for the efforts. Distance gained, zero. 

Personally I have learned a ton about the P39 I didn’t know, and some of you have done exquisite work in unraveling the Experts “information” either by timeline or context. It’s much appreciated by myself, and I believe others.

Good luck.

Biff

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## Thumpalumpacus (Jul 15, 2021)

33k in the air said:


> When, oh when, will we get a Brewster Buffalo Expert?
> 
> What is being done for the army P-39 needs to be done for the navy's F2A!



This sounds like a job for 

 SaparotRob
!

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## SaparotRob (Jul 15, 2021)

Thanks! I know just how to do it. Hello buffnut453. Calling buffnut453!

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## eagledad (Jul 15, 2021)

Biff

Well put and I heartly agree. Enjoy your bacon for breakfast!

Eagledad

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## SaparotRob (Jul 15, 2021)

Inspired by the "Most overrated fighter of WW 2", I had just spent about 40 minutes trying to figure out the range of a mid 1943 P-47 to compare it to a mid 1943 P-39. It's tougher than I thought and I think I can't trust the Wiki numbers. I'm guessing it's some average or a cherry picked distance of a specific model I can't link to. I'm thinking that with the right date or models I could see for myself if the P-47 had a better combat radius than the Airacobra. Clean airframes, no tanks. 
Am I the only one who has to scroll up to see just what thread I'm posting to as they all seem to be the Groundhog thread?


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## SaparotRob (Jul 15, 2021)

Gee willikers, He's got me looking up technical info!

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## Shortround6 (Jul 15, 2021)

SaparotRob said:


> Gee willikers, He's got me looking up technical info!


You have to use numbers in the range charts in the flight manuals. 
Many of which are on this web site. 


Other Mechanical Systems Tech.



And you have to use a bit of common sense. 
For example the P-47 at 14,000lbs could use around 100 gallons of fuel just warming up, taking off and climbing to 25,000ft. The initial warm up and take-off are done on internal fuel. 

Operational radius is always much less then than even 1/2 the range.

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## buffnut453 (Jul 15, 2021)

P-39 Expert said:


> This was a one-off example. I have shown numerous times how a properly equipped 1942 P-39 would have weighed 7150 lbs.
> 
> Bell did show how P-39 weight could be reduced by 1000lbs in May 1943. Details were not provided in the book.



That's absolutely priceless. You criticize me for finding one whole mark of Spitfire that exceeded 12,000lb AUW (let's ignore for the moment that I actually identified 2 different marks, plus another 2 that exceeded 10,000lb) and yet you're staking your claims for a high-performance P-39 on a single airframe? You should go on the stage....you'd have them rolling in the aisles.

The bottom line is that Bell was on entirely the wrong track with the P-39. Every customer was asking for higher altitudes, higher speeds, longer range and heavier weapons. Putting the engine in the middle of the fuselage imposed a lot of additional structural weight and limited growth potential for bigger engines. For aircraft like the Spitfire, changing from the Merlin to the much more powerful Griffon was relatively straightforward because most of the structure aft of the firewall remained unchanged (yes, the tailplane and rudder were enlarged on later versions...but those are relatively minor changes). Trying to shoehorn a larger engine into the P-39 essentially involves a redesign of the entire airframe; it's not airframe growth, it's a completely new design.

While other manufacturers were incorporating more powerful engines, Bell's only response was to tinker within the limits of the P-39 design. For example, we have the continual flip-flopping on the weight of armour installed in different versions. That wasn't happening because of changing operational requirements. It was simply an example of Bell trying to eke out performance from an airframe that lacked growth potential.

Look at this from the customer perspective. You have every manufacturer out there bolting on new, more powerful, engines to improve performance and cope with increased weights. Then you have Bell tweaking round the edges to reduce weight. Given that procurement is trying to plan months in advance, where would you put your money if you were responsible for buying aircraft? Would you invest in designs that were demonstrating growth potential to meet operational needs or place orders with a company that's futzing with the same basic design with only modest performance improvements (and at the cost of operational equipment/weapons/fuel)?

It's interesting to consider Bell's postwar work which, from a high-performance fighter perspective, focused on one-off or limited-run experimental types. That work aligns pretty well with the behaviours exhibited by the company during WW2, tweaking one-off airframes to maximize performance.

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## pbehn (Jul 15, 2021)

SaparotRob said:


> Gee willikers, He's got me looking up technical info!


The range given for an aircraft is under certain conditions. Escorts operated under escort conditions. The P-39 if tasked to escort a US bomber formation would be getting close to where maximum speed and stall speed are the same and so cruising speed is maximum speed also. The range of a fighter is the start point for the operational planners who have to build in all the things that use fuel up and then build in contingencies for screw ups. If you draw a line from Norwich in the middle of East Anglia where many bombers were to Berlin you go across almost all the heavily defended industrial areas of NW Germany and the Netherlands so you cant take a straight line.

On August 17 1943 the Schweinfurt Regensburg raid saw RAF Spitfires escorting to Antwerp with P-47s taking over as far as Eupen, 82 miles further.

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## Shortround6 (Jul 15, 2021)

You have four companies that used Allison engines.
The P-39 and P-40 are the most contemporary.
The Mustang was a bit late and unloved by the USAAC 
The P-38 was a twin and used turbos. 

The P-40 was a 1934/35 design with a new engine tacked on. Curtiss did rather well with it as it was the right plane at the right time. It's time had gone past by 1943/44 though. 
Bell P-39 was later in design and Bell mucked things up by trying to be too clever. Too much "stuff" in too small an airframe. No idea on how to design cooling ducts or place radiators/oil coolers and so on. 
Instead of taking the bull by the horns and building a slightly larger airframe they seemed to want to take stuff out (like fuel) and blame the customer for not seeing the brilliance of the design. 
The fact that the plane couldn't reach the enemy with less fuel and was therefore useless seemed to go over their head  

US didn't need point interceptor bomber destroyers in 1942-43. 
The Idea behind the 37mm cannon (which Bell and the USAAC held onto for far too long) was to destroy very large bombers like the US bomber Mafia was dreaming about (see B-15 and B-19). Turns out the 37mm wasn't really needed, yes it could kill smaller aircraft rather well given a hit but it was hard to hit with. 
USAAC hung onto the 37mm for quite some time in other prototypes. 
.


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## GregP (Jul 15, 2021)

DerAdlerIstGelandet said:


> Best post ever.


Regarding the "Urchin-Snouted Codiece" comment, I offer this spreadsheet I created some years ago to generate Monty Python insults. Simply follow the instructions.

I am in Las Vegas right now with VERY SLOW internet. I'll post the Shakspearian Insult file when I get home tomorrow.


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## SaparotRob (Jul 15, 2021)

pbehn said:


> The range given for an aircraft is under certain conditions. Escorts operated under escort conditions. The P-39 if tasked to escort a US bomber formation would be getting close to where maximum speed and stall speed are the same and so cruising speed is maximum speed also. The range of a fighter is the start point for the operational planners who have to build in all the things that use fuel up and then build in contingencies for screw ups. If you draw a line from Norwich in the middle of East Anglia where many bombers were to Berlin you go across almost all the heavily defended industrial areas of NW Germany and the Netherlands so you cant take a straight line.
> 
> On August 17 1943 the Schweinfurt Regensburg raid saw RAF Spitfires escorting to Antwerp with P-47s taking over as far as Eupen, 82 miles further.


I wanted to see if the P-47 variant that was operational on say, Bastille Day 1943, was competitive in range to the Airacobra variant OPERATIONAL on that same day. I came up with P-47D -25RE (?) and the P-39D. I looked at the range charts for the P-47, no external fuel, on that section's second page. After some eye strain, I went out for errands. I think it was statute 760 miles, not nautical miles. So divide in half, 380 miles. Now eliminate the fooling around time, whatever percentage that is which would leave us with 275 miles. 
I then started looking up the range charts of the P-39 and as the Lord is my witness, I didn't want to read anything more about the P-39.

I wanted to just briefly respond to your post. It's too late for that.
I understand that the distance to the target is not a straight line. Someone brought up the woefulness of the P-47's range in this, the P-39 thread. So I started to look for myself. I think the P-39's range was less than that. I have not yet completed my research. Nor will I ever.

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## SaparotRob (Jul 15, 2021)

Of course, your mileage may vary.

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## GrauGeist (Jul 15, 2021)

Shortround6 said:


> USAAC hung onto the 37mm for quite some time in other prototypes.


It's almost comical how some air forces were obsessed with certain things.
With the USAAC/USAAF, the 37mm seemed to be their holy grail of combat.
Aside from the P-39/P-63, they fooled with the P-38, XP-58, XP-67 (which was planned to be armed with six!), XA-41 (planned to be armed with four), XP-72 (two or four) and XP-54 (two).

I'm sure I'm forgetting some, too...


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## pbehn (Jul 15, 2021)

SaparotRob said:


> Of course, your mileage may vary.


Pilots and mission planners generally didnt deal in miles, it was all relative to fuel. A late poster here said that for him a long mission was 11 hours in a B-17. A long mission in a P-51 was six hours, and that is close to what humans can do regularly on such missions. A Merlin burns fuel at about 50 gallons per hour when running economically and 3 times that on full power. With 200gals ext fuel and 265 int fuel it has enough for over 9 hrs economical running which shows how much everything eats into its economy. For all these planes the absolute maximum for consideration is how far it can go on internal fuel having dropped its tanks and had 15-20 minutes combat. There was a 170 gal slipper tank for a Spitfire which could get you to a place you just cant get back from

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## 33k in the air (Jul 15, 2021)

SaparotRob said:


> I wanted to see if the P-47 variant that was operational on say, Bastille Day 1943, was competitive in range to the Airacobra variant OPERATIONAL on that same day.



The general rule-of-thumb is to take the range and divide by three. That will get you a reasonable approximation of the combat radius. (The actual fraction, of course, varies with the details.)

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## 33k in the air (Jul 15, 2021)

Shortround6 said:


> You have to use numbers in the range charts in the flight manuals.
> Many of which are on this web site.
> 
> 
> ...



And radius can be extended by such things as including the distance covered in climbing to combat altitude, or by changing the amount of reserve fuel allotted.


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## Peter Gunn (Jul 15, 2021)

SaparotRob said:


> Of course, your mileage may vary.


I see what you did there...

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## Peter Gunn (Jul 15, 2021)

Thumpalumpacus said:


> This sounds like a job for
> 
> SaparotRob
> !


See my post #2,232, he's too busy becoming the Edsel expert...

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## P-39 Expert (Jul 15, 2021)

pbehn said:


> So they used something heavier? So what is your point? How can you claim the British wanting things that increased weight was perfidy when the US was doing exactly the same. BTW you are doing that thing again where your "never" becomes not "often". Of those 100,000 the P-39s used by the USA as a weapon was also an insignificant amount.
> 
> And how does that look against a P-38, P-47, Mustang I, Spitfire IX, Typhoon? Would you cross the Channel to take on an Fw 190 with it?


My point is: British were specifying 30cals on P-400s when shortly the AAF/USN would move on to 50cals and cannon.

A 1942 P-39/400 at 7150lbs looks pretty good against P-38s since they weren't in combat until late 1942. P-47 was not in combat until spring 1943. Would outclimb a Mustang I and go about the same top speed. Spitfire IX started in mid '42 but production didn't get rolling until :ate '42. Would outclimb a Typhoon and about as fast. As far as a FW190A5 it would be outclimbed by a 7150lb P-39/400.


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## P-39 Expert (Jul 15, 2021)

buffnut453 said:


> And it was also specified in the Bell Model 13, P-39C which suggests the British did NOT specify the gas heater. This has been raised several times but you keep ignoring this fact.
> 
> If the gas heater was useless, then it's down to Bell who included it as standard equipment in the Model 13. The British would simply have ensured cockpit heating was provided...it was down to Bell to ensure the heating system worked correctly.


See my post #2617.


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## P-39 Expert (Jul 15, 2021)

pbehn said:


> Yes the British were experimenting in the BoB with cannon, that was a year before the P-39 arrived in UK. You have repeatedly quoted the performance of your 1942 super light P-39 as being useful in Europe, even suggesting it could be used as a bomber escort.


Never suggested a 1942 P-39 could be used as a bomber escort. Escort by AAF P-47 didn't begin until Spring '43.


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## P-39 Expert (Jul 15, 2021)

nuuumannn said:


> It's worth noting that one of the main reasons why the RAF rejected the Airacobra was compass deviation when its guns were fired, at rates as high as 160 degrees, which rendered it completely useless. This was clearly unacceptable to the British, but eventually, a fix was found, although by that time the decision had been made to replace the Airacobras in service with Spitfire Vs, which had better performance at any rate. Did the US forces ever record this as an issue with the P-39?


No.


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## P-39 Expert (Jul 15, 2021)

nuuumannn said:


> Did it improve the type's performance at all?


One example. One. Improved climb to 5000' by 25%.


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## P-39 Expert (Jul 15, 2021)

Shortround6 said:


> Yes, The list is upthread somewhere but here it is again.
> 
> This was serial number 41-38291, a P-39D-1. first in standard configuration and then modified.
> Removal of the four wing guns and supporting accessories, all of the gear box armor plate, the oxygen system, all radio equipment, all instruments except the altimeter, the airspeed indicator, engine manifold pressure gage, tachometer, temperature and pressure gauges; all tools and fixed equipment not essential for flight at 5,000ft, all ballast and four of the eight self-sealing fuel cells. This saved 1287lbs. On page 159 of "Cobra!" by Birch Mathews.
> The only performance figures given are for time to 5,000ft, radius of turn and stalling speed. Time to climb 5,000ft dropped from 2 min 34 sec to 1 min 54 sec.


One test example. One. Never intended as an operational airplane.


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## P-39 Expert (Jul 15, 2021)

Juha3 said:


> Your original claim was "_Yes the British were still using 30calMGs after the BoB, but the AAF WAS NOT_." Again, when shown that you were wrong, your changed your claim, as you always do. 1/5 of USAAC fighters in Philippines on 7 Dec 1941 were P-40Bs (18) and 1/5 P-35s (18), and there were definitely P-40Bs on Oahu.
> 
> And most of the great aces of the WWII acknowledged that surest way to make a kill was open fire at close range, 200 yds was a good range to make a kill in early 40s. And on effectiveness of the .303, on 6 Jan 1940 Sarvanto shot down six Soviet DB-3Fs, these had armour and self-sealing fuel tanks, in five minutes while flying in Fokker D.XXI, 4 7.7 mm Brownings. And those six were not only claims, all six wrecks were found and nowadays we know from Russian documents that only one of 8 DB-3Fs of that formation returned and 7 were shot down the 7th by Sovelius. Sarvanto was exceptionally good shot and as Finns were trained opened fire at close range and probably all or three of his mgs were loaded with Italian APIs, the 4th might have been loaded with trackers. The downside of the close range tactic was that Sarvanto's plane was hit 23 times during the engagemant.


If I'm reading your post correctly there were 36 operational P-40s and P-35s with 30calMGs? Out of 100000 AAF and USN fighters with 50cals and or cannons? That's .00036%. 

200yds was way too short ranged. One had to get within 200yds of a fighter to have a good chance at a victory? Or within 200yds of a bomber that was returning fire? The 30s didn't have enough hitting power or range. That's why the AAF/USN used 50calMGs and the British progressed to the 20mm cannon.


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## pbehn (Jul 15, 2021)

P-39 Expert said:


> My point is: British were specifying 30cals on P-400s when shortly the AAF/USN would move on to 50cals and cannon.
> 
> A 1942 P-39/400 at 7150lbs looks pretty good against P-38s since they weren't in combat until late 1942. P-47 was not in combat until spring 1943. Would outclimb a Mustang I and go about the same top speed. Spitfire IX started in mid '42 but production didn't get rolling until :ate '42. Would outclimb a Typhoon and about as fast. As far as a FW190A5 it would be outclimbed by a 7150lb P-39/400.


Shortly the British would be specifying cannon so if you dont like .303s put in the cannon. There were 6 squadrons of Mk IX Spitfires at Dieppe along with six squadrons of Mustang Is. Shortly after a Spitfire IX intercepted a Ju 86 at 42,000ft Where does your P-39 fit in here?
It didnt go "about the same top speed" as a Mustang I it was slower and the Mustang I could go prodigious distances carrying cameras, guns, cod pieces and false legs. There is no virtue in outclimbing a Typhoon or Mustang, you are climbing into your adversary's strong suite.


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## P-39 Expert (Jul 15, 2021)

Peter Gunn said:


> Uh... what?
> 
> I see you cherry pick around the P-40 and P-51 marques that were armed with .30's which surprises me not in the least.
> 
> ...


How many P-40s with 30calMGs actually got into combat with the AAF/USN? The Mustang I with the 30s was an export model for the British. 

Original F4F with 30s was a prototype. No operational F4Us had 30s. Did the F2A actually see combat with the USN?

An Airacobra with 7 30calMGs is absolutely the lamest idea ever. 

If you don't have radar at your base then USING IFF is down.right.stupid. Your words, not mine.


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## Milosh (Jul 15, 2021)

P-39 Expert said:


> Out of 100000 AAF and USN fighters with 50cals and or cannons?


The USAAF and USN had 100,000 fighters in 1941?


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## Milosh (Jul 15, 2021)

P-39 Expert said:


> Never suggested a 1942 P-39 could be used as a bomber escort.


Sure you have.

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## pbehn (Jul 15, 2021)

P-39 Expert said:


> If I'm reading your post correctly there were 36 operational P-40s and P-35s with 30calMGs? Out of 100000 AAF and USN fighters with 50cals and or cannons? That's .00036%.
> 
> 200yds was way too short ranged. One had to get within 200yds of a fighter to have a good chance at a victory? Or within 200yds of a bomber that was returning fire? That's why the AAF/USN was using 50calMGs and the British progressed to the 20mm cannon.


To validate your claim you need to find all the aircraft in US service in Nov 1940 with 0.5" and 0.3"

It was obviously the other way around, the USA themselves werent "using" anything in anger until Dec 1941, by that time all the new British fighter were or could be fitted with cannon.


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## Milosh (Jul 15, 2021)

P-39 Expert said:


> Did the F2A actually see combat with the USN?


Yes.

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## Just Schmidt (Jul 15, 2021)

P-39 Expert said:


> If I'm reading your post correctly there were 36 operational P-40s and P-35s with 30calMGs? Out of 100000 AAF and USN fighters with 50cals and or cannons? That's .00036%.


Are you 100% percent sure you double-checked your math on this one?

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## P-39 Expert (Jul 15, 2021)

Shortround6 said:


> Lets try again.
> P-39K at 6663lbs tactical empty from the weight chart in the manual.
> Take out 100lbs worth of .30 cal guns or even add another 20lbs for "extras"
> take out 100lbs of armor. leaving you with what the P-39C had.
> ...


Now let's finalize this weight discussion:
P-39K empty weight 5658lbs including voice and IFF radios, oxygen.
2x50calMGs + ammo 275lbs.
37mm cannon + ammo 300lbs
Gun sight 4 lbs
Armor plate & Glass 122lbs (as in N model without nose armor)
Pilot 200lbs
Oil 71lbs including the 2gal reduction gear box
Full internal fuel 720lbs
Gross weight 7350lbs
Deduct 50lbs for "misc. eq. for 30cal guns" from the P-39C pilot's manual. Shows 25lbs for 2x30s, K model has 4x30s. Without 30s you don't need their "misc. eq.".
Deduct 110lbs for IFF per AHT for 1942 NG
Deduct pilot 40lbs as earlier models used 160lbs incl. parachute
Gross weight 7150lbs-what I've been telling you all along.
Substitute 20mm cannon with 120rds ammo 200lbs. 20mm was more reliable in 1942, include 37mm cannon in M/N/Q models that didn't need any weight reduction.
Gross weight 7050lbs.

Straight from the Pilot's Manual. An armored warplane with self sealing fuel tanks and cannon/heavy machine gun armament. Optimal configuration for 1942.


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## pbehn (Jul 15, 2021)

P-39 Expert said:


> Now let's finalize this weight discussion:
> P-39K empty weight 5658lbs including voice and IFF radios, oxygen.
> 2x50calMGs + ammo 275lbs.
> 37mm cannon + ammo 300lbs
> ...


To do what?


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## P-39 Expert (Jul 15, 2021)

Milosh said:


> Yes.


Well, when and where?


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## pbehn (Jul 15, 2021)

duplicate


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## pbehn (Jul 15, 2021)

P-39 Expert said:


> Well, when and where?


Post # 1965 
"Stop putting words in my mouth. I have never said that the P-39 was able to do the Mustang's job. I have said that P-39s could have escorted B-17/24s in Europe, certainly not as far or as well."

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## Shortround6 (Jul 15, 2021)

P-39 Expert said:


> Now let's finalize this weight discussion:
> P-39K empty weight 5658lbs including voice and IFF radios, oxygen.
> 2x50calMGs + ammo 275lbs.
> 37mm cannon + ammo 300lbs
> ...


Wrong weights.
The IFF was 40 to 45 lbs,not 110.
140lb pilots in shoes and flight suits/ equipment are going to be scarce. And strangely, American P-39s with 20mm guns carried 70-88 lbs of ballast in addition to the gear box armor.
71lbs of oil is not enough for 120 gallons of fuel.

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## Milosh (Jul 15, 2021)

P-39 Expert said:


> Well, when and where?


Use your I-net search skills.


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## pbehn (Jul 15, 2021)

Milosh said:


> Use your I-net search skills.


Forum search key word "escort" by poster P-39 Expert. It not only shows he said it but he also says he has said it before, I really dont know where this is going, its just trollery.

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## Milosh (Jul 15, 2021)

He was asking about the F2A.

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## P-39 Expert (Jul 15, 2021)

SaparotRob said:


> I wanted to see if the P-47 variant that was operational on say, Bastille Day 1943, was competitive in range to the Airacobra variant OPERATIONAL on that same day. I came up with P-47D -25RE (?) and the P-39D. I looked at the range charts for the P-47, no external fuel, on that section's second page. After some eye strain, I went out for errands. I think it was statute 760 miles, not nautical miles. So divide in half, 380 miles. Now eliminate the fooling around time, whatever percentage that is which would leave us with 275 miles.
> I then started looking up the range charts of the P-39 and as the Lord is my witness, I didn't want to read anything more about the P-39.
> 
> I wanted to just briefly respond to your post. It's too late for that.
> I understand that the distance to the target is not a straight line. Someone brought up the woefulness of the P-47's range in this, the P-39 thread. So I started to look for myself. I think the P-39's range was less than that. I have not yet completed my research. Nor will I ever.


P-47D-25 didn't get to combat until mid-'44. P-39D was operational mid-'42. That's two full years. 

To get combat radius go to the Flight Operation Instruction Chart in the P-47 pilot's manual. Take total fuel including 110gal drop tank 415gal. Then compute the "fooling around time" as you put it by deducting the takeoff and climb allowance 45gal, 20 minute combat reserve 90gal, and 20 minute reserve for landing 25gal. The net fuel 255gal can be used for cruising is divided by 105 gallons per hour at 25000' yielding 2.4hours cruising time. Multiply by 285mph TAS cruising speed (190 IAS) for a total of 684mi. Divide by 2 for 342mi combat radius. 

Put that into perspective with Berlin being 520mi from England. P-47 came up a little (a lot) short. This computation uses the most economical setting (105gph) for the P-47 at 25000'. Most charts give the P-47 with drop tank a combat radius of 375mi but that is still way short of Berlin.

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## Juha3 (Jul 15, 2021)

P-39 Expert said:


> If I'm reading your post correctly there were 36 operational P-40s and P-35s with 30calMGs? Out of 100000 AAF and USN fighters with 50cals and or cannons? That's .00036%.
> 
> 200yds was way too short ranged. One had to get within 200yds of a fighter to have a good chance at a victory? Or within 200yds of a bomber that was returning fire? The 30s didn't have enough hitting power or range. That's why the AAF/USN used 50calMGs and the British progressed to the 20mm cannon.


Lol, no it means that on 7 Dec 1941 40% of the USAAC first-line fighters in Philippines were armed with .300 mgs, Wiki says that most of USAAC fighters on Oahu were P-40Bs, I had exact numbers in my attic, but because you do not mind facts, why bother, you like to use wiki, so be it. Now that means that when the Pacific War began, most of the USAAC fighters there were armed with .300s (plus also with two 0.5s). That was over a year after the end of the BoB. You can read from the AHT that the USAAC got some 350 P-40s with .300 wing guns.

Maybe this thread gives to you some idea on air combat RAF Fighter Gunnery Analysis the main point to understand air gunnery and air combat is that to achieve a kill in 99.9% of the cases you must first hit the enemy a/c.


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## Just Schmidt (Jul 15, 2021)

P-39 Expert said:


> Well, when and where?


There's this incident known as the battle of Midway.

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## DerAdlerIstGelandet (Jul 15, 2021)

P-39 Expert said:


> If I'm reading your post correctly there were 36 operational P-40s and P-35s with 30calMGs? Out of 100000 AAF and USN fighters with 50cals and or cannons? That's .00036%.
> 
> 200yds was way too short ranged. One had to get within 200yds of a fighter to have a good chance at a victory? Or within 200yds of a bomber that was returning fire? The 30s didn't have enough hitting power or range. That's why the AAF/USN used 50calMGs and the British progressed to the 20mm cannon.



Uh, when did the US have 100,000 fighters operational at one time?

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## gordonm1 (Jul 15, 2021)

I have been watching History Channel Battlezone on the net about early war and they said the USA took P400's from a Brittish order after Pearl Harbor for fighting at Guadacanal. They were delivered without oxygen and I presume no pessurization so their ceiling was 12,000 ft. The other planes they had were Navy/Marine Wildcats which could go higher so the island hopping begins with the Americans having reasons to avoid it's use in the Pacific. The Wildcats were said to use them as bait and it helped the Wildcat pilots get experience diving and zooming and booming I bet the P40's also had a higher ceiling (WIKI 29,000 ft for p40E) even if they were not at Guadacanal until the marines moved on. This bad start for the type would explain to me why we had so many to give to the Russians where they fought at lower altitude(and probably loved the big gun).

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## Glider (Jul 15, 2021)

P-39 Expert said:


> My point is: British were specifying 30cals on P-400s when shortly the AAF/USN would move on to 50cals and cannon.
> 
> A 1942 P-39/400 at 7150lbs looks pretty good against P-38s since they weren't in combat until late 1942. P-47 was not in combat until spring 1943. Would outclimb a Mustang I and go about the same top speed. Spitfire IX started in mid '42 but production didn't get rolling until :ate '42. Would outclimb a Typhoon and about as fast. As far as a FW190A5 it would be outclimbed by a 7150lb P-39/400.


The problem of course being that there was no 7150lbs P39. 
The Typhoon was faster, climbed faster, had more firepower, had better armour protection, carried considerably more payload, had a better range and didn't have the nasty handling habits. Something we debated in some detail earlier on and you seem to have forgotten.

PS Still waiting for your observations of the British deliberately sabotaging the P39's performance.


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## pbehn (Jul 15, 2021)

P-39 Expert said:


> Put that into perspective with Berlin being 520mi from England. P-47 came up a little (a lot) short. This computation uses the most economical setting (105gph) for the P-47 at 25000'. Most charts give the P-47 with drop tank a combat radius of 375mi but that is still way short of Berlin.


No it didnt, the only thing that comes up short is your ability to read, comprehend and remember. On a heavy long range daylight bombing raid no bomber or escort fighter took off and headed for the target, once you understand that you are making progress.


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## SaparotRob (Jul 15, 2021)

P-39 Expert said:


> P-47D-25 didn't get to combat until mid-'44. P-39D was operational mid-'42. That's two full years.
> 
> To get combat radius go to the Flight Operation Instruction Chart in the P-47 pilot's manual. Take total fuel including 110gal drop tank 415gal. Then compute the "fooling around time" as you put it by deducting the takeoff and climb allowance 45gal, 20 minute combat reserve 90gal, and 20 minute reserve for landing 25gal. The net fuel 255gal can be used for cruising is divided by 105 gallons per hour at 25000' yielding 2.4hours cruising time. Multiply by 285mph TAS cruising speed (190 IAS) for a total of 684mi. Divide by 2 for 342mi combat radius.
> 
> Put that into perspective with Berlin being 520mi from England. P-47 came up a little (a lot) short. This computation uses the most economical setting (105gph) for the P-47 at 25000'. Most charts give the P-47 with drop tank a combat radius of 375mi but that is still way short of Berlin.


Are those figures for my "Bastille Day 'Bolt" or my wrong choice, the P-47D-25 RE?


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## pbehn (Jul 15, 2021)

DerAdlerIstGelandet said:


> Uh, when did the US have 100,000 fighters operational at one time?


1942, and 500% were P-39s, we have run into real number, time and type problems here, the decimal point is like an IFF set, you can put it anywhere.

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## FLYBOYJ (Jul 15, 2021)

P-39 Expert said:


> P-47D-25 didn't get to combat until mid-'44. P-39D was operational mid-'42. That's two full years.
> 
> To get combat radius go to the Flight Operation Instruction Chart in the P-47 pilot's manual. Take total fuel including 110gal drop tank 415gal. Then compute the "fooling around time" as you put it by deducting the takeoff and climb allowance 45gal, 20 minute *combat reserve *90gal, and 20 minute *reserve for landing* 25gal. The net fuel 255gal can be used for cruising is divided by 105 gallons per hour at 25000' yielding 2.4hours cruising time. Multiply by 285mph TAS cruising speed (190 IAS) for a total of 684mi. Divide by 2 for 342mi combat radius.
> 
> Put that into perspective with Berlin being 520mi from England. P-47 came up a little (a lot) short. This computation uses the most economical setting (105gph) for the P-47 at 25000'. Most charts give the P-47 with drop tank a combat radius of 375mi but that is still way short of Berlin.


I stopped debating flight manual charts with you because you don't now how to use them properly and refuse to listen to people on here who are actual pilots and flown real airplanes, and I don't want to continually bang my head against the wall. There is no "combat reserve" or "landing reserve," that is calculated within your flight planning. A 30 or 45 minute reserve is what is normally planned into a mission should something happen and you have to extend. It's quite obvious that many missions were flown well into the reserve calculation.

*I'm not going to debate this with you!!!!*

To the other members partaking in these discussions, any "calculations" our friend here comes up with regards to flight planning and using flight manual charts, I would really double check if you have access to the data/ flight manual.

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## pbehn (Jul 15, 2021)

FLYBOYJ said:


> I stopped debating flight manual charts with you because you don't now how to use them properly and refuse to listen to people on here who are actual pilots and flown real airplanes, and I don't want to continually bang my head against the wall. There is no "combat reserve" or "landing reserve," that is calculated within your flight planning. A 30 or 45 minute reserve is what is normally planned into a mission should something happen and you have to extend. It's quite obvious that many missions were flown well into the reserve calculation.
> 
> *I'm not going to debate this with you!!!!*
> 
> To the other members partaking in these discussions, any "calculations" our friend here comes up with regards to flight planning and using flight manual charts, I would really double check if you have access to the data/ flight manual.


P-39 is fighting his own war in his own plane making his own calculations about how he will attack Berlin, I guess the bombers will just have to hunker on in behind. When you read Parks instructions to controllers saying two good squadrons climbing together to 30,000ft take 15% longer than one squadron then its clear things arent as simple as an individual planes performance. Drgondogs recent post on another thread shows how complex things were and what the room to manoeuvre for the escorts was.

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## P-39 Expert (Jul 15, 2021)

Juha3 said:


> Lol, no it means that on 7 Dec 1941 40% of the USAAC first-line fighters in Philippines were armed with .300 mgs, Wiki says that most of USAAC fighters on Oahu were P-40Bs, I had exact numbers in my attic, but because you do not mind facts, why bother, you like to use wiki, so be it. Now that means that when the Pacific War began, most of the USAAC fighters there were armed with .300s (plus also with two 0.5s). That was over a year after the end of the BoB.
> 
> Maybe this thread gives to you some idea on air combat RAF Fighter Gunnery Analysis the main point to understand air gunnery and air combat is that to achieve a kill in 99.9% of the cases you must first hit the enemy a/c.


Joe Baugher says 131 P-40Bs and 193 P-40Cs were produced for the AAF for a grand total of 324 produced. And maybe 60 P-35As. These early P-40s and P-35s represent .4% (that's 4 tenths of one percent) of the 100000 fighters produced by America for the AAF/USN. Totally insignificant by any measure. The rest had 50calMGs/cannon. Except for the P-39.

One could say that all the AAF/USN fighters in combat were armed with 50calMGs and/or cannon, but he would only be 99.96% correct. Except for P-39s.


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## pbehn (Jul 15, 2021)

P-39 Expert said:


> Joe Baugher says 131 P-40Bs and 193 P-40Cs were produced for the AAF for a grand total of 324 produced. And maybe 60 P-35As. These early P-40s and P-35s represent .4% (that's 4 tenths of one percent) of the 100000 fighters produced by America for the AAF/USN. Totally insignificant by any measure. The rest had 50calMGs/cannon. Except for the P-39.
> 
> One could say that all the AAF/USN fighters in combat were armed with 50calMGs and/or cannon, but he would only be 99.96% correct. Except for P-39s.


The discussion is about planes in service at the end of October 1940, not the end of the war, you have just done that goalpost thing again.


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## P-39 Expert (Jul 15, 2021)

pbehn said:


> The discussion is about planes in service at the end of October 1940, not the end of the war, you have just done that goalpost thing again.


The discussion is about how many AAF/USN fighters had 30calMGs in WWII. We weren't even at war in October 1940, not for another year.

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## pbehn (Jul 15, 2021)

P-39 Expert said:


> The discussion is about how many AAF/USN fighters had 30calMGs in WWII. We weren't even at war in October 1940, not for another year.


But that isnt how the discussion started, it was about the cheating British wanting heavy armament in the P-39 when they didnt have them in their own. I said that they were using cannon in 1940 Spitfires and you made your statement about US airplanes. So the discussion is about the end of the BoB. It doesnt matter to me that the USA wasnt at war, the UK was.


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## SaparotRob (Jul 15, 2021)

Okay, here's what I'm trying to figure out. Remember the map of Europe posted once, having concentric circles indicating fighter escort ranges? Had it been there, how far would the semi circle go for the the P-39? Say mid 1943.


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## pbehn (Jul 15, 2021)

SaparotRob said:


> Okay, here's what I'm trying to figure out. Remember the map of Europe posted once having concentric circles indicating fighter escort ranges? Had it been there, how far would the semi circle go for the the P-39? Say mid 1943.


Inside the Spitfire.

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## SaparotRob (Jul 15, 2021)

Appreciate it, Brother.


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## pbehn (Jul 15, 2021)

SaparotRob said:


> Appreciate it, Brother.


How far you can go depends on altitude and rated altitude and a lot of other things, the Spitfire MkIX and Mk VIII were short ranged but could cruise at 25,000ft the P-39 couldnt cruise at that altitude it could just stay there for a short while.

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## SaparotRob (Jul 15, 2021)

As I have read so many times before from so many of our fellow posters.


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## GrauGeist (Jul 15, 2021)

P-39 Expert said:


> If I'm reading your post correctly there were 36 operational P-40s and P-35s with 30calMGs? Out of 100000 AAF and USN fighters with 50cals and or cannons? That's .00036%.
> 
> 200yds was way too short ranged. One had to get within 200yds of a fighter to have a good chance at a victory? Or within 200yds of a bomber that was returning fire? The 30s didn't have enough hitting power or range. That's why the AAF/USN used 50calMGs and the British progressed to the 20mm cannon.


First of all, 200 yards is 600 feet or roughly an eighth of a mile - this is a distance where many fighters engaged.
They didn't stand off and shoot laser beams at five miles.
As for the piddly .30 caliber, the Axis types claimed thousands of Allied air craft with their piddly 7mm MGs.
The British held the Luftwaffe at bay with their piddly .303s during the Battle of Britain.
So why was that?
Did it possess a mystical P-39ish power that defies physics?
Or was it simply because a .30/7mm round will pass through wood, aluminum skin, glass and human bodies at ranges over 3,000 feet.

And entire world war was being fought with .30/7mm weapons before the US entered. They just didn't sit around for four years (in the Orient) and two years (in Europe) wondering what they could use to shoot down an enemy aircraft - the .50 delivered a harder punch, doing more damage for each round delivered, yes, but just because an aircraft was armed with them, didn't mean it had invincibility.
A KI-43 could shoot down a P-40 armed with .50MGs just as easy as it xould shoot down a P-40 armed with .30MGs.

Regarding the .30 armed P-40, there were several hundred manufactured (not including exports) before the D model.
They saw action at Pearl Harbor, the Philippines and other areas of the Pacific.

The SBD was one of the first US aircraft to be designed and built with the .50MG as it's armament (two in the cowl). Up to that point, it was common for fighters to have a mix of one .30 and one .50 OR being being solely armed by .30s, which, prior to WWII, was a world standard.

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## buffnut453 (Jul 15, 2021)

P-39 Expert said:


> See my post #2617.



I did see your post #2617 (I actually read the stuff you write and respond to it) and it makes no mention of the P-39C (Model 13).

On one of the many threads you've turned into a P-39 Groundhog Day, you made the following statement in the context of additional "useless" items specified by the British for the P-400 (Source: SHOULD the P39 have been able to handle the Zero? Was it training or performance?):

“…_and other such items as a cockpit heater that was fueled by kerosene when the P-39 already had probably the best cockpit climate control system of any American fighter that simply ducted hot air from the radiator_”

I'll summarize the Bell Model numbers again in case you missed it the first 3 times I posted it:

*Model 13 (P-39C) *- Equipped with the gas-fuelled heater just as per the P-400 (Source: Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained))

*Model 14 (P-400)* - Had the same gas-fuelled heater as the P-39C. Per the above quote, you are claiming that the British specified the "useless" gas heater when the P-39 already had "probably the best cockpit climate control system" using ducted air from the radiator. The problem is the ducted air solution doesn't appear until after the Model 14A-1 below.

*Model 14A (P-39D-1)* - Same gas-fuelled heater as the P-39C (Source: Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained))

*Model 14A-1 (P-39D-2) *- Same gas-fuelled heater as the P-39C (Source: Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)).


It seems that the ducted-air heating solution wasn't present in the P-39 until after the P-39D-2. I need you to explain how it is that the P-400 had a ducted air cockpit heating that seemingly didn't appear until a much later Bell Model number? None of this is covered in your Post #2617 so please, share your expertise and explain how I'm wrong (again).

One final point. In Post #2617 you state that the gas-fuelled heater was useless because of its impact on the radio. As pointed out in my previous post, that's the fault of Bell for not integrating the heater effectively with the other aircraft systems. That is NOT the fault of the British. However, take out the gas-fuelled heater from the P-39C/D-1/D-2 and P-400 and you're left with a fighter that has no cockpit heating. How good will the aircraft's high-altitude performance be if the pilot is frozen?

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## pbehn (Jul 15, 2021)

SaparotRob said:


> As I have read so many times before from so many of our fellow posters.


Do you really think that was for you to read?

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## SaparotRob (Jul 15, 2021)

Nope.


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## ThomasP (Jul 16, 2021)

I don't look at this thread for 1 day and you guys manage almost 4 full pages.

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## Juha3 (Jul 16, 2021)

P-39 Expert said:


> Joe Baugher says 131 P-40Bs and 193 P-40Cs were produced for the AAF for a grand total of 324 produced. And maybe 60 P-35As. These early P-40s and P-35s represent .4% (that's 4 tenths of one percent) of the 100000 fighters produced by America for the AAF/USN. Totally insignificant by any measure. The rest had 50calMGs/cannon. Except for the P-39.
> 
> One could say that all the AAF/USN fighters in combat were armed with 50calMGs and/or cannon, but he would only be 99.96% correct. Except for P-39s.


So you looked at Baugher pages and missed P-40G and that even the plain P-40s had "_Provisions were made for the mounting of one 0.30-inch machine gun in each wing_" I do not have a slightest idea, did the USAAC ever utilize this provision. And have you ever wondered why it took so long for Bell to produce a P-39 model with .50 wing armament? After all after the P-400 order the USAAC/USAAF was for a while the main and only customer of Bell before the SU began to receive them in increasing numbers and began demand even more.


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## pbehn (Jul 16, 2021)

Juha3 said:


> So you looked at Baugher pages and missed P-40G


From what I read that is what a P-40G is. The British asked for 4 x 0.303 wing guns, the US asked for 20 wings and put them on their own P-40s which were called P-40Gs. It said some went to Russia some were retained but didnt give details, didnt even say if "20 wings" were individual or pairs.


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## Peter Gunn (Jul 16, 2021)

P-39 Expert said:


> How many P-40s with 30calMGs actually got into combat with the AAF/USN? The Mustang I with the 30s was an export model for the British.



*Re P-40s:* Virtually all of them in the Phillipines, Pearl Harbor, Dutch Harbor... *Re Mustang:* No sh!t Sherlock, you're the one claiming it never had .30's in it.



P-39 Expert said:


> Original F4F with 30s was a prototype. No operational F4Us had 30s. Did the F2A actually see combat with the USN?


*Re F4F and F4U:* No sh!t Sherlock, you're the one claiming they never had .30's not me. *Re F2A:* Yes.



P-39 Expert said:


> An Airacobra with 7 30calMGs is absolutely the lamest idea ever.


No lamer then trying to remove nose armor and IFF and a host of other equipment to make the plane even more out of balance, at least here the CoG wouldn't be as effed up and 7 .30's with liberal application of tracer would pretty much shred any Japanese aircraft. According to your logic it would be knocking Zeke's down from Henderson to 7 Mile with ease.
(See, I can make hasty generalizations and pontificate them as facts as well)



P-39 Expert said:


> If you don't have radar at your base then USING IFF is down.right.stupid. Your words, not mine.


Name an operational area where the P-39 was flying in that didn't have radar, I'll wait.

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## Peter Gunn (Jul 16, 2021)

pbehn said:


> Post # 1965
> "Stop putting words in my mouth. I have never said that the P-39 was able to do the Mustang's job. I have said that P-39s could have escorted B-17/24s in Europe, certainly not as far or as well."


No to mention...


P-39 Expert said:


> Only difference between air combat in western Europe and eastern Europe was there were no high altitude bombers in Eastern Europe. And those weren't really a force in the west until mid '43. Soviets standard combat formation was the "Kuban Stairs" or "Flying Bookshelves" with a flight (4 planes) at 5000meters (16500ft), a flight at 6000meters (20000ft) and the top flight at 7000meters (23000ft). * P-39s could match the LW fighters up to 8000meters (26400ft) with neither side willing to go much higher than that.
> 
> Turbocharged B-17s and B-24s flew at 25000ft with their escorts a little higher. Not much difference.*

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## Shortround6 (Jul 16, 2021)

According the the Curtiss Fighter book 






The only P-40 without wing guns was XP-40.
The 200 P-40s had a single gun in each wing. 
It is not clear if the French, who ordered 230 Hawk 81A aircraft in on Oct, 9th 1940 were the start of the 4 gun (two each side) wings on the P-40 but it seems very likely. 
The book does say that after the British took over the French order the early aircraft (first one flown June 6th, 1940) the planes were armed with either two Colt .50 cal cowl guns and four British Browning .303 wing guns or two Colt .50s cowl guns and four Colt .30 wing guns. 
However it appears that some of the early Tomahawks may have been delivered with only one gun in each wing. 
A report by a Lt. Hubert Zemke (  ) dated July 28th 1941 on the British experience with the P-40/Tomahawk up till then lists the most serious short coming as a lack of fire power as the British were have endless troubles with cowl .50 cal guns leaving the planes with only two or four rifle caliber guns. 
The US got/built/modified at least 46 aircraft into P-40Gs. At least 21 went to England and some were sent from there to Russia. 
records are a mess as at least 17 aircraft got new serial numbers and in the range used (originally for P-40Ls that got canceled) 5 serial numbers appear to be unused. 

The P-40B was a rationalization of a combat worthy P-40 and H81A-2 (Tomahawk IIA) with the least amount of minor equipment variation for more efficient production. 
All P-40Bs got 4 guns in the wings. 

This four gun wing was not that great a trick as In Sept of 1939 two P-36As were modified to carry more guns, the XP_36D had four guns in the wings (two each side) and two .50 cal in cowl and the XP-36E had eight .30 cal guns in wings (four each side) with a single .50 in cowl (not operational for the tests). 

The French in their 2nd order for Hawk 75s (an option on the first order) dates from March 8th 1939 and added two 7.5mm F.N. guns (Brownings) to the existing two guns in the wing and two in the cowl. Deliveries of the A-2 version with 6 guns (or provision for 6 guns, not sure where/when Belgian built guns were installed) started in May of 1939 and 97 had been delivered by the end of Sept, 1939. This is the start of the 6 gun export Hawk 75s. 

Interest in planes with many guns/lots of firepower sure seems high in the early days of the war.

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## buffnut453 (Jul 16, 2021)

Juha3 said:


> Lol, no it means that on 7 Dec 1941 40% of the USAAC first-line fighters in Philippines were armed with .300 mgs, Wiki says that most of USAAC fighters on Oahu were P-40Bs, I had exact numbers in my attic, but because you do not mind facts, why bother, you like to use wiki, so be it. Now that means that when the Pacific War began, most of the USAAC fighters there were armed with .300s (plus also with two 0.5s). That was over a year after the end of the BoB. You can read from the AHT that the USAAC got some 350 P-40s with .300 wing guns.
> 
> Maybe this thread gives to you some idea on air combat RAF Fighter Gunnery Analysis the main point to understand air gunnery and air combat is that to achieve a kill in 99.9% of the cases you must first hit the enemy a/c.



Don't forget the P-36s still in front-line service with the USAAF, some 39 of which were at Pearl Harbor, which also had 30 cal armament.

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## Juha3 (Jul 16, 2021)

pbehn said:


> From what I read that is what a P-40G is. The British asked for 4 x 0.303 wing guns, the US asked for 20 wings and put them on their own P-40s which were called P-40Gs. It said some went to Russia some were retained but didnt give details, didnt even say if "20 wings" were individual or pairs.


Both AHT and Baugher say 44 P-40Gs of which 16 were sent to the SU.


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## Juha3 (Jul 16, 2021)

buffnut453 said:


> Don't forget the P-36s still in front-line service with the USAAF, some 39 of which were at Pearl Harbor, which also had 30 cal armament.


Thanks, how I could forget that?

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## SaparotRob (Jul 16, 2021)

Juha3 said:


> Thanks, how I could forget that?


Groundhog Fatigue?


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## buffnut453 (Jul 16, 2021)

SaparotRob said:


> Groundhog Fatigue?

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## BiffF15 (Jul 16, 2021)

buffnut453 said:


> View attachment 632411



Roadkill…. How appropriate.

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## Snautzer01 (Jul 16, 2021)

BiffF15 said:


> Roadkill…. How appropriate.


No just pining for the fjords

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## Greg Boeser (Jul 16, 2021)

Peter Gunn said:


> *Re P-40s:* Virtually all of them in the Phillipines, Pearl Harbor, Dutch Harbor... *Re Mustang:* No sh!t Sherlock, you're the one claiming it never had .30's in it.
> 
> 
> *Re F4F and F4U:* No sh!t Sherlock, you're the one claiming they never had .30's not me. *Re F2A:* Yes.
> ...


No .30 cal armed P-40s at Dutch Harbor. P-40s at Otter Point were P-40Es. These replaced the P-36s initially stationed in Alaska at the start of the war.
I can only find one combat action involving USN F2As, a strafe of a Japanese submarine in late 1941 or early 1942. It's in _The First Team._
Midway based Marines used them to shoot down a H8K1 in March 1942, and then got slaughtered on June 4th.

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## pbehn (Jul 16, 2021)

Peter Gunn said:


> No to mention...


Can you stop posting this, I cringe when I see posts about B-17s at 25,000ft it didnt happen, or it was rare, or it was in a different era, anyway removing a compass saved 2 Lbs, so that is this argument sorted.

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## GregP (Jul 16, 2021)

OK, back from a week in Las Vegas. Boy, was it hot!

From a couple of days back, I posted something that got some good reactions because I used a Monty Python Shakspearian type insult for the P-39. Now, as promised, you, too, can insult people and airplanes with aplomb.

I offer this spreadsheet. either pick one choice from each of three columns or follow the instruction to generate a random insult. This is not password protected, but insult away at your own risk. I assume no liability for your musings using this handy insult reference.

Enjoy, you loggerheaded clay-brained malt-worm! That insult was from inputting 24, 7, 33 into the inputs after you enable editing.

I have another spreadsheet for coming up with proposal buzzwords. 

For instance, if I input a 3-digit number, say ... 257 ... into the buzzword spreadsheet, I get "systematized logistical projection." It is a phrase that can be dropped into virtually any report with that ring of decisive knowledgeable authority. No one will have the remotest idea of what you are talking about, but the important thing is THEY ARE NOT ABOUT TO ADMIT IT.

I attached it, too. Enjoy, and don't get fired using this crap. It's all for fun only.

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## 33k in the air (Jul 17, 2021)

Who can forget this classic:

"Your mother was a hamster, and your father smelt of elderberries!"

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## P-39 Expert (Jul 17, 2021)

buffnut453 said:


> I did see your post #2617 (I actually read the stuff you write and respond to it) and it makes no mention of the P-39C (Model 13).
> 
> On one of the many threads you've turned into a P-39 Groundhog Day, you made the following statement in the context of additional "useless" items specified by the British for the P-400 (Source: SHOULD the P39 have been able to handle the Zero? Was it training or performance?):
> 
> ...


Ducted air heating system was present on the P-39D.

Regarding your last paragraph, the ducted air heat system on the domestic models was much superior to the gas fueled system on the export models so it was discontinued. For impact on frozen pilots, see the P-38.


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## P-39 Expert (Jul 17, 2021)

GrauGeist said:


> First of all, 200 yards is 600 feet or roughly an eighth of a mile - this is a distance where many fighters engaged.
> They didn't stand off and shoot laser beams at five miles.
> As for the piddly .30 caliber, the Axis types claimed thousands of Allied air craft with their piddly 7mm MGs.
> The British held the Luftwaffe at bay with their piddly .303s during the Battle of Britain.
> ...


Most AAF/USN fighters had their wing 50cals harmonized at 300-350 yards.


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## P-39 Expert (Jul 17, 2021)

GregP said:


> OK, back from a week in Las Vegas. Boy, was it hot!
> 
> From a couple of days back, I posted something that got some good reactions because I used a Monty Python Shakspearian type insult for the P-39. Now, as promised, you, too, can insult people and airplanes with aplomb.
> 
> ...


Your weight and balance spreadsheet was much more useful.

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## pbehn (Jul 17, 2021)

P-39 Expert said:


> Ducted air heating system was present on the P-39D.
> 
> Regarding your last paragraph, the ducted air heat system on the domestic models was much superior to the gas fueled system on the export models so it was discontinued. For impact on frozen pilots, see the P-38.


I thought the heating system was for the guns as well as the pilot?


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## P-39 Expert (Jul 17, 2021)

FLYBOYJ said:


> I stopped debating flight manual charts with you because you don't now how to use them properly and refuse to listen to people on here who are actual pilots and flown real airplanes, and I don't want to continually bang my head against the wall. There is no "combat reserve" or "landing reserve," that is calculated within your flight planning. A 30 or 45 minute reserve is what is normally planned into a mission should something happen and you have to extend. It's quite obvious that many missions were flown well into the reserve calculation.
> 
> *I'm not going to debate this with you!!!!*
> 
> To the other members partaking in these discussions, any "calculations" our friend here comes up with regards to flight planning and using flight manual charts, I would really double check if you have access to the data/ flight manual.


I'm simply using the Flight Operation Instruction Chart according to the directions provided. "If the original flight plan calls for a mission with changes in power or speed the flight should be broken down into a series of individual short flights and then added together to make up the total flight and it's requirements." 20 minutes of combat would be at a higher power setting and 20 minute reserve for landing would be at a lower power setting. 

I really don't understand what there is to debate.


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## GrauGeist (Jul 17, 2021)

P-39 Expert said:


> Most AAF/USN fighters had their wing 50cals harmonized at 300-350 yards.


The convergence points varied greatly, depending on type, mission, weapon arrangement, theater and time period.

Some pilots even had their own formulas, like Lt. Drew's P-51D, which was up for three points of convergence:
200 yards, 250 yards and 300 yards.

Maj. Chick had his P-47D set up for 100 yards.

And on the other side of the fence, Erich Hartmann had his Bf109 set up for 53 yards.

The further the distance to target, the higher the need for deflection aiming. The closer to target, the higher the probability of saturating the target.


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## buffnut453 (Jul 17, 2021)

P-39 Expert said:


> Ducted air heating system was present on the P-39D…the ducted air heat system on the domestic models was much superior to the gas fueled system on the export models so it was discontinued.



But the P-39C was a domestic model and it had the gas heater. 
S
 Shortround6
also provided pilot manuals for the D-1 and D-2 which also showed they had the gas heater.

Please provide a source for your assertion that the D had ducted air heating.


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## P-39 Expert (Jul 17, 2021)

SaparotRob said:


> Okay, here's what I'm trying to figure out. Remember the map of Europe posted once, having concentric circles indicating fighter escort ranges? Had it been there, how far would the semi circle go for the the P-39? Say mid 1943.


Using a P-39N with 120gal internal and 110gal drop tank (230gal) deduct 20gal for takeoff and climb, 25gal for 20min combat at 25000' and 10gal for 20min landing reserve at 5000'. The remaining 175gal (cruise) is divided by 62gallons per hour giving a flight time of 2.8hrs multiplied by 276mphTAS = 772mi. Half that is the combat radius 385mi. Be conservative and say 370mi. For perspective Berlin was 520mi.

This is carrying the drop tank the whole mission. If the tank is dropped then cruising speed increases to 350mph at the same power (62gph) and range increases accordingly.


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## Vincenzo (Jul 17, 2021)

P-39 Expert said:


> Using a P-39N with 120gal internal and 110gal drop tank (230gal) deduct 20gal for takeoff and climb, 25gal for 20min combat at 25000' and 10gal for 20min landing reserve at 5000'. The remaining 175gal (cruise) is divided by 62gallons per hour giving a flight time of 2.8hrs multiplied by 276mphTAS = 772mi. Half that is the combat radius 385mi. Be conservative and say 370mi. For perspective Berlin was 520mi.
> 
> This is carrying the drop tank the whole mission. If the tank is dropped then cruising speed increases to 350mph at the same power (62gph) and range increases accordingly.


your calculation is fault, you can not choice when drop the tank, at best it's just before of fight, so 120-55=65 so your radius is around 1 hour, if you are not attacked before

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## FLYBOYJ (Jul 17, 2021)

P-39 Expert said:


> I'm simply using the Flight Operation Instruction Chart according to the directions provided. "If the original flight plan calls for a mission with changes in power or speed the flight should be broken down into a series of individual short flights and then added together to make up the total flight and it's requirements." 20 minutes of combat would be at a higher power setting and 20 minute reserve for landing would be at a lower power setting.
> 
> I really don't understand what there is to debate.


*There is NO "RESERVE" for landing* - that part of the flight is factored into the entire flight plan unless you intend to fly at military power over the field for 20 minutes (or whatever your emergency reserve is, usually 30 to 45 minutes). Pilot 101, or in your case "Joe Pilot".

"reserve" "tail cone" "in balance" "Joe pilot" Groundhog jargon.

You're right, there is nothing to debate


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## P-39 Expert (Jul 17, 2021)

pbehn said:


> I thought the heating system was for the guns as well as the pilot?


It was, heated cockpit air was ducted from the rudder pedal wells up to blow directly on the cannon and twin 50calMGs and then exhausted through the small exit ducts near the nose. Very efficient system.


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## pbehn (Jul 17, 2021)

P-39 Expert said:


> Using a P-39N with 120gal internal and 110gal drop tank (230gal) deduct 20gal for takeoff and climb, 25gal for 20min combat at 25000' and 10gal for 20min landing reserve at 5000'. The remaining 175gal (cruise) is divided by 62gallons per hour giving a flight time of 2.8hrs multiplied by 276mphTAS = 772mi. Half that is the combat radius 385mi. Be conservative and say 370mi. For perspective Berlin was 520mi.
> 
> This is carrying the drop tank the whole mission. If the tank is dropped then cruising speed increases to 350mph at the same power (62gph) and range increases accordingly.


I hope you forward this to your opponent as your terms of engagement. What are your cruising figures at 25,000ft and how long does it take to get there? P-39 Performance Tests

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## P-39 Expert (Jul 17, 2021)

FLYBOYJ said:


> *There is NO "RESERVE" for landing* - that part of the flight is factored into the entire flight plan unless you intend to fly at military power over the field for 20 minutes (or whatever your emergency reserve is, usually 30 to 45 minutes). Pilot 101, or in your case "Joe Pilot".
> 
> "reserve" "tail cone" "in balance" "Joe pilot" Groundhog jargon.
> 
> You're right, there is nothing to debate


There is a reserve for landing in case the base is closed by weather or the pilot becomes lost. And 10 gallons of fuel certainly won't let the pilot cruise at low altitude at military power for 20 minutes. How is landing the plane factored into the entire flight plan without creating a reserve for that section of the flight? 

I thought we weren't going to debate this anymore.


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## P-39 Expert (Jul 17, 2021)

Vincenzo said:


> your calculation is fault, you can not choice when drop the tank, at best it's just before of fight, so 120-55=65 so your radius is around 1 hour, if you are not attacked before


Certainly ANY fighter with external tanks must return early if forced to drop the tanks before their fuel is exhausted.


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## FLYBOYJ (Jul 17, 2021)

P-39 Expert said:


> There is a reserve for landing in case the base is closed by weather or the pilot becomes lost. And 10 gallons of fuel certainly won't let the pilot cruise at low altitude at military power for 20 minutes. How is landing the plane factored into the entire flight plan without creating a reserve for that section of the flight?
> 
> *I thought we weren't going to debate this anymore.*


I wasn't debating I was pointing out that your armchair flight training is once again wrong.

Yes there is no debate. You can believe what you want - if pilots (joe Pilots and test pilots included) did their flight plans the way you have described in some of your post, parachute companies would have made a lot more money. I want the rest of the membership to see your errors and it seems they already have.

No debate - just facts...


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## pbehn (Jul 17, 2021)

If a 110 gallon external tank has so little effect on performance why would they ever get dropped? What was the cruise speed power setting at 25,000ft with a 110gal tank?


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## Vincenzo (Jul 17, 2021)

P-39 Expert said:


> Certainly ANY fighter with external tanks must return early if forced to drop the tanks before their fuel is exhausted.


but in your example the tank is too large for the internal fuel available, the tank is usable only for the cruise in, a tanker larger of 70 gal for the P-39 with 120 gals, if your info on the consume are right, is useless, is a waste of fuel

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## GregP (Jul 17, 2021)

Regarding Post 2747, if you drop the tank, yes, the speed increases, but you also lose all the fuel remining in the drop tank.

Figure it will be dropped on the way into the target since the enemy KNOWS you need the drop tank or you wouldn't have one in the first place. If I were the enemy, I'd send in fighter to hit as soon as possible so their ranges would be greatly reduced.

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## Shortround6 (Jul 17, 2021)

Basic combat radius. 

120 gallons internal. 
Minus 10-15 gal for take-off. Some fuel will be slowly returned in cruise.
Minus your 10-14 gallon "landing reserve".
Minus your combat allowance.
That is the fuel you have to get home after dropping the tank/s.

If you are only burning 25 gallons in 20 minutes you aren't making enough power to win in combat.

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## pbehn (Jul 17, 2021)

P-39 Expert said:


> This is carrying the drop tank the whole mission. If the tank is dropped then cruising speed increases to 350mph at the same power (62gph) and range increases accordingly.


I dont think there can be any doubt now that you are just trolling. The maximum speed of the P-39N was about 375MPH, its cruising speed at 15,000ft cruising altitude was 250MPH, Your consumption in cruise at 62gph is only marginally less than your combat 25 gals in 20 mins that is 75gph. most engines used circa 3 times the fuel on max power that they used in cruise.

BTW the idea of escorting bombers flying at 25K while you are at 15K is just funny, not only does it take 6 minutes to get up there, you would have many missions flying in cloud and hopelessly lost.

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## 33k in the air (Jul 17, 2021)

P-39 Expert said:


> Using a P-39N with 120gal internal and 110gal drop tank (230gal) deduct 20gal for takeoff and climb, 25gal for 20min combat at 25000' and 10gal for 20min landing reserve at 5000'. The remaining 175gal (cruise) is divided by 62gallons per hour giving a flight time of 2.8hrs multiplied by 276mphTAS = 772mi. Half that is the combat radius 385mi. Be conservative and say 370mi. For perspective Berlin was 520mi.
> 
> This is carrying the drop tank the whole mission. If the tank is dropped then cruising speed increases to 350mph at the same power (62gph) and range increases accordingly.



Your calculations are incorrect.

(1) The P-39N-0/1 consumed 147 gallons per hour at full military power. The usual rule for combat fuel allowance was 15 minutes at full military power and 5 minutes at war emergency power. The latter isn't listed on the charts, so let's just go with 15 minutes of full military power.

147 / 60 * 15 = 36.75 gallons

The combat fuel allowance is closer to 37 gallons, not the 25 gallons you stated.

(2) At a take-off weight of 8,000 lbs, the P-39N-0/1 consumed a total of 39.7 gallons of fuel to climb to 25,000 according to the climb data section of the Take-off, Climb, and Landing chart.

The fuel consumed in climbing to 25,000 feet is closer to 40 gallons, not the 20 gallons you stated.

(3) Reserve fuel allowance normally used in radius calculations is thirty minutes, not twenty. Using Column V (max. range) for 7,500 to 7,100 lbs weight, fuel consumption per hour is about 35 gallons per hour. Call it 17 gallons for half an hour.

The fuel reserve is 17 gallons, not the 10 gallons you stated.

(4) The combat radius is determined by how far the aircraft can fly back on internal fuel after deducting allowances for warm-up, initial take-off, combat, and reserve (assuming the cruise out can be done mostly on external fuel in drop tanks).

At 120 gallons full internal: 120 - 37 - 17 = 66 gallons left to cruise back to base.

(Note that the internal fuel remaining would actually be slightly less than 66 gallons, since warm-up, take-off, and initial climb are done on internal fuel before switching over to external fuel. But let's use 66 to be generous.)

Using your own figures of 62 gallons per hour at a TAS of 276 MPH for the cruise back yields the following:
66 / 62 * 276 = 293.8 miles


See the relevant charts on pages 26-28 of the PDF found here:
Pilot's Flight Operating Instructions -- P-39N-0 and P-39N-1 Airplanes

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## 33k in the air (Jul 17, 2021)

pbehn said:


> I dont think there can be any doubt now that you are just trolling. The maximum speed of the P-39N was about 375MPH, its cruising speed at 15,000ft cruising altitude was 250MPH, Your consumption in cruise at 62gph is only marginally less than your combat 25 gals in 20 mins that is 75gph. most engines used circa 3 times the fuel on max power that they used in cruise.



Fuel usage for military power and war emergency power usage is listed in the upper left corner of the charts in the Flight Operating Instruction Manuals.

I don't know how the P-39 Expert missed that, but evidently he did.

For the P-39N-0/1, military power consumed 147 gallons per hour. (It doesn't list a value for war emergency power fuel consumption.) Allotting 15 minutes for military power equals 36.75 gallons consumed.

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## FLYBOYJ (Jul 17, 2021)

33k in the air said:


> Your calculations are incorrect.
> 
> (1) The P-39N-0/1 consumed 147 gallons per hour at full military power. The usual rule for combat fuel allowance was 15 minutes at full military power and 5 minutes at war emergency power. The latter isn't listed on the charts, so let's just go with 15 minutes of full military power.
> 
> ...


I've come up with similar before. Our friend is confusing allowances for reserves and seems to use parts of the charts that will give the aircraft the most range, ignoring the 30 minutes reserve for emergency. Great post!


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## 33k in the air (Jul 17, 2021)

FLYBOYJ said:


> I've come up with similar before. Our friend is confusing allowances for reserves and seems to use parts of the charts that will give the aircraft the most range, ignoring the 30 minutes reserve for emergency. Great post!



He put in the reserve allowance, but underestimated it by using 20 minutes instead of 30 minutes. He also apparently has the aircraft carrying the drop tank out and back, which is odd.

The P-39 manual I referenced only has IAS figures for the cruising values, so there's the question of what exactly those convert to in TAS. Later USAAF manuals included a TAS column.

It also doesn't say anything about a 110-gallon drop tank; the only size explicitly mentioned is 75 gallons. From the manuals of other aircraft, the drag caused by a 75-gallon drop tank was evidently the same as for a 500-lb bomb.


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## Shortround6 (Jul 17, 2021)

The reason the P-39 burned so little fuel at 25,000 ft is because it made so little power.
It isn't going to come close to making even military power. Figure roughly a 2.5 percent loss of power for every 1,000 ft higher than 15,000ft. Adjust for exact FTH. 
The plane didn't have much reserve power above max cruise. It's ability to actually fight ( manuever ) at those altitudes and not just fly straight and level was limited.
If the fight descends lower the P-39 gets more power but the fuel burn goes way up.

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## FLYBOYJ (Jul 17, 2021)

33k in the air said:


> He put in the reserve allowance, but underestimated it by using 20 minutes instead of 30 minutes. He also apparently has the aircraft carrying the drop tank out and back, which is odd.
> 
> *The P-39 manual I referenced only has IAS figures for the cruising values, so there's the question of what exactly those convert to in TAS. Later USAAF manuals included a TAS column.*


I found that depending on the manual there is a IAS to TAS chart based on a what I believe is a lapse rate calculation (true airspeed is an additional roughly 2% higher than indicated airspeed for each 1,000 feet above sea level) which is the most inaccurate way to calculate this.


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## pbehn (Jul 17, 2021)

According to Parks instructions. a good squadron takes up to 4 minutes longer than a test pilot to reach 25,000ft. two squadrons take 10-12% longer than that and three squadrons 15-18% longer. There maybe good reasons why escort squadrons did not have the same experience but I doubt it is hugely different. 

When in contact with a bomber formation, the speed is the ground speed of the bombers, escorts can cruise at a speed to conserve fuel or to be fast enough not to be bounced, fuel used is how much is consumed between RV points. Using an individual aircraft performance to compare operational combat radii doesnt work.

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## GrauGeist (Jul 17, 2021)

P-39 Expert said:


> I really don't understand what there is to debate.


Perhaps if you paid attention to the mountains of information being provided (often given in intricate detail), you would better understand the Bell product that's the subject of "debate".
In regards to a "debate", there really isn't one - rather it's a case of you stating flawed data and others providing correct data.
Then you completely ignore the accurate data and regurgitate the same flawed data or alter it to back an altered claim, which is once again corrected by accurate data (often times from military sources).
Then you proceed to ignore the peer reviewed, manufacturer's, military's and actual pilot's information and proceed to post flawed, skewed, cherry-picked or imaginary information/data over and over and over and over and over and over and over and over and over and over and over...

It's not even close to a debate, it's called an endless loop.

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## Milosh (Jul 17, 2021)

pbehn said:


> According to Parks instructions. a good squadron takes up to 4 minutes longer than a test pilot to reach 25,000ft. two squadrons take 10-12% longer than that and three squadrons 15-18% longer.


Wasn't that the problem with Bader's Big Wing during the BoB?

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## Thumpalumpacus (Jul 17, 2021)

pbehn said:


> According to Parks instructions. a good squadron takes up to 4 minutes longer than a test pilot to reach 25,000ft. two squadrons take 10-12% longer than that and three squadrons 15-18% longer. *There maybe good reasons why escort squadrons did not have the same experience but I doubt it is hugely different.*
> 
> When in contact with a bomber formation, the speed is the ground speed of the bombers, escorts can cruise at a speed to conserve fuel or to be fast enough not to be bounced, fuel used is how much is consumed between RV points. *Using an individual aircraft performance to compare operational combat radii doesnt work.*




[Emphasis added -- Thump]

Forming up takes both time and fuel. I don't understand why our friend here doesn't seem to take that into account.


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## Milosh (Jul 17, 2021)

Formation flying also consumes more fuel as the throttle is always being moved.

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## 33k in the air (Jul 17, 2021)

33k in the air said:


> At 120 gallons full internal: 120 - 37 - 17 = 66 gallons left to cruise back to base.
> 
> (Note that the internal fuel remaining would actually be slightly less than 66 gallons, since warm-up, take-off, and initial climb are done on internal fuel before switching over to external fuel. But let's use 66 to be generous.)
> 
> ...



Based on the P-39N-0/1 original internal fuel load of 87 gallons:

87 - 37 - 17 = 33 gallons left for the cruise back to base.

Using the same 62 gallons per hour at a TAS of 276 MPH that P-39 Expert gave:
33 / 62 * 276 = 146.9 miles.

So increasing the internal fuel from 87 to 120 gallons (+33 gallons, which is 198 lbs of weight) results in the radius being doubled.

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## pbehn (Jul 17, 2021)

Milosh said:


> Wasn't that the problem with Bader's Big Wing during the BoB?


Exactly although the situation is different, his big wing weren't all at the same airfield and took an age to form up. To turn the big wing and keep formation meant very, very slow turns or those on the inside had to almost stall while those on the outside couldn't keep up.

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## pbehn (Jul 17, 2021)

33k in the air said:


> Based on the P-39N-0/1 original internal fuel load of 87 gallons:
> 
> 87 - 37 - 17 = 33 gallons left for the cruise back to base.
> 
> ...


Groundhoggery is almost as difficult to fathom as Turingery and Banburismus.

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## pbehn (Jul 17, 2021)

Milosh said:


> Formation flying also consumes more fuel as the throttle is always being moved.


And you have to make a decision if people cant keep up. Oh and you only find out if your plane isnt performing as per the manual when your engine starts sputtering.


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## Thumpalumpacus (Jul 17, 2021)

Milosh said:


> Formation flying also consumes more fuel as the throttle is always being moved.



That's my non-piloting understanding as well; it's the same reason my truck gets better mileage using cruise-control than it does when I'm throttling through traffic, right? And in my truck, cruise control is near-useless in traffic because I must consistently adjust throttle to "fly" with traffic. It's great on open highway when everyone is doing the same speed. It follows that I get better mileage driving an empty road than stop-and-go through a freeway jam.

How much more-so it must be when working in three dimensions rather than two. Now I have to throttle up or back for altitude as well as flight-speed. And we've yet to talk about the time it takes to formate and fly out, which is another drain on fuel.

It's why you'll never see mpg-performance (measured on an isolation track here in America) matched by real-world conditions.

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## Milosh (Jul 17, 2021)

Book learning (theory) is useless without the practical experience to go with it.

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## FLYBOYJ (Jul 17, 2021)

Thumpalumpacus said:


> That's my non-piloting understanding as well; it's the same reason my truck gets better mileage using cruise-control than it does when I'm throttling through traffic, right?


Exactly! I've flown formation in GA aircraft, a T-34 with a Bonanza and Debonair and in an L29 with 3 other aircraft. I found the jet to be the hardest as it took a few moments for the jet to spool up and when once you got momentum it was tricky to slow down (speed brakes). To throw some gasoline into the fire, we haven't even brought up this fact during our range/ fuel calculations, let alone not flying in a straight formation, constantly making shallow turns within the flight while not only making yourself a harder target but scanning for enemy aircraft. Sorry chaps, I've might have added another week to Groundhog Day!

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## GrauGeist (Jul 17, 2021)

I know I've mentioned this before, but a friend of ours was a B-24 pilot and he spoke of the complexities of large bomber formation missions.
It was not as simple as just taking off and heading to the target.
A typical mission start would be to take off and climb to a certain altitude where his group would form up on their Judas Goat.
Meanwhile hundreds of other B-24s were doing this at the same time, circling for a considerable amount of time waiting for everyone to break out of the overcast, get their bearings and assemble.
The climb to altitude and the assembly loiter consumed quite a bit of fuel before they even got underway.

The.escort groups would be going through similar motions: take off, climb to altitude and loiter for assembly - this burns up alot of fuel before the mission even gets underway.

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## GregP (Jul 17, 2021)

From the Manual for P-39N-1-BE. Gross weight at startup: 7,967 lbs. So, use the figures for 8,000 lbs.

1. Total Fuel on Board with 75 gal drop tank: 167 gal.

2. Combat climb to 15,.000 feet: Book says 35.2 gal. used and it takes 6.9 minutes. That leaves 126.8 gal. Books says climb speed is 150 mph. Assume about a 15° climb. So, Y = 15,000 feet and angle = 15°. So, the horizontal distance is about 10.6 miles travelled during the 6.9 minutes of climb.

3. Assume we allow for 10 minutes of combat. Combat would be at 44.5 MAP and 147 gal per hour per 8,000 pound chart, top left. 10 minutes at 147 gph burns 24.5 gallons, leaving 102.3 gallons of fuel. I can’t say if the combat takes you closer to home or farther away from home. Assume it does neither.

4. So, I have 102.3 US gallons of fuel. Assume I decide to cruise at 15,000 feet at 2,400 rpm and 208 mph. I burn 70 gph of fuel, so I can only cruise for 102.3/70 = 1.46 hours. 1.46 hours at 208 mph = 303.97 miles. Call it 304 miles. OK, I went 10.6 miles during climb and I can cruise for 304 miles before I am a glider pilot.

5. Then: 304 miles + 10.6 miles = 314.6 miles. Assume I can turn around instantly, so my range is 314.6/2 = 157.3 miles before I run out of fuel.

That doesn’t allow for much use attacking a target even 200 miles away in the Pacific Ocean. Or, suppose you only have 5 minutes of combat. That extends the range from 157.3 miles to 175 miles. Not overly useful from a tactical point of view. A range increase from 157 miles to 175 miles offers very little gain for a fighter mission. You could increase your range at 15,000 feet all the way to 193.6 miles, but then you have no fuel for combat if you want to get home. Not too useful if YOU are flying.

Of course, if you are a suicide pilot, you COULD ram something 387 miles away just as you turned into a glider pilot, assuming no combat time at all until you hit what you are ramming.

All of the above assumes I don't have to drop the 75-gallon tank because the combat happens before I used up all the drop tank fuel. If I DO have to drop it, the range decreases proportionately for fuel unavailable above.

I was likely being kind when I called the P-39N a loggerheaded, swag-bellied, hedge pig ... uuhhh ... groundhog.

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## Vincenzo (Jul 17, 2021)

GregP also your calculation are fault, when you stay at 102.3 gals, 75 are in the drop tank but you don't fight with the drop tank in, so you actually radius is with 27.3 gals so counting the 10 miles of climb a bit more of 90 miles total

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## pbehn (Jul 17, 2021)

Thumpalumpacus said:


> [Emphasis added -- Thump]
> 
> Forming up takes both time and fuel. I don't understand why our friend here doesn't seem to take that into account.


Unusually for me I was trying to be fair. Parks instructions were for pilots and squadrons and wings that had to climb to high altitude above their airfields, not to some RV point over the N Sea, that may be done more economically, I dont know. But the general point is the same, you cant do the same with a lot of anything that you can with one or two. Ask a school teacher about going on a walk with 30 children or their own 2 sons/daughters. To me the significant thing in Parks instructions was reference to a "good squadron", he was no longer a pilot he was a commander, in statistics he would refer to a good squadron and in his other work try to turn a bad squadron into a good one, thereby upping the average, in this case by decreasing time taken.

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## Thumpalumpacus (Jul 17, 2021)

pbehn said:


> To me the significant thing in Parks instructions was reference to a *"good squadron"*, he was no longer a pilot he was a commander, in statistics he would refer to a good squadron and in his other work try to turn a bad squadron into a good one, thereby upping the average, in this case by decreasing time taken.



[Emboldening added -- Thump]

You're right that that is an unusual qualifier. It's not a word a commander puts into a report without drawing significance to that modifier.


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## FLYBOYJ (Jul 17, 2021)

GregP said:


> From the Manual for P-39N-1-BE. Gross weight at startup: 7,967 lbs. So, use the figures for 8,000 lbs.
> 
> *I was likely being kind when I called the P-39N a loggerheaded, swag-bellied, hedge pig ... uuhhh ... groundhog.*


Try the same calculations at 20 or 25,000 feet! We beat this horse to death several dozen pages ago of course to no avail.

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## pbehn (Jul 17, 2021)

FLYBOYJ said:


> Try the same calculations at 20 or 25,000 feet! We beat this horse to death several dozen pages ago of course to no avail.


After "proving" that the P-39N could have been one of the periods best interceptors, we are now seeing the proof that it could also have been the second best long range escort fighter, if only the fools could have seen it at the time.

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## Thumpalumpacus (Jul 17, 2021)

FLYBOYJ said:


> [...] To throw some gasoline into the fire, we haven't even brought up this fact during our range/ fuel calculations, let alone not flying in a straight formation, constantly making shallow turns within the flight while not only making yourself a harder target but scanning for enemy aircraft.



And now the planes on either outlier of the formation are having to horse the throttles around even more as the formation turns to and fro' doing the escort weave. This in a plane that might not get me to the bathroom without a refueling stop.

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## FLYBOYJ (Jul 17, 2021)

Thumpalumpacus said:


> And now the planes on either outlier of the formation are having to horse the throttles around even more as the formation turns to and fro' doing the escort weave. This in a plane that might not get me to the bathroom without a refueling stop.


If you maintain a V or finger 4. The Germans had a good technique (I think developed by Molders) where the wingman would move up while the lead tightened his turn, this was done simultaneously within a 4 plane formation.

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## 33k in the air (Jul 17, 2021)

Thumpalumpacus said:


> And now the planes on either outlier of the formation are having to horse the throttles around even more as the formation turns to and fro' doing the escort weave. This in a plane that might not get me to the bathroom without a refueling stop.



Hence why the relay escort method came into use. Rather than staying with the bombers all the way, greatly reducing escort range, now the fighters flew at their own cruising speed to the rendezvous point, met up with bombers, escorted them for about 100 miles or half an hour, at which point they were relieved by the next escort fighter group.

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## Shortround6 (Jul 17, 2021)

GregP said:


> . Assume we allow for 10 minutes of combat. Combat would be at 44.5 MAP and 147 gal per hour per 8,000 pound chart, top left. 10 minutes at 147 gph burns 24.5 gallons, leaving 102.3 gallons of fuel.


This only applies if combat was at around 15,000ft.

At 25,000ft the Allison is making about 770hp while in flat out level speed or about 740hp when climbing (less RAM). 

Of course even a fuel burn of 94 gallons a hour means 31-32 gallons for a combat allowance for 20 minutes and not 25 gallons. 

If the plane descends to 20,000ft the power goes to about 900 hp (higher in level flight, lower in climb) but the fuel burn goes from about 1.5 gallons per minute to about 1.9 gal per minute. 

Power figures from the P-39Q test. 

The "expert" seems to think that the P-39, which is starving for air and thus can't burn any more fuel, is going to get both good gas consumption and good performance.

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## nuuumannn (Jul 17, 2021)

Milosh said:


> Wasn't that the problem with Bader's Big Wing during the BoB?



Pretty much, a wee snippet from my well-thumbed copy of Bungay's The Most Dangerous Enemy:

"Assuming it climbed at its optimal speed [I'm assuming he means Best Rate Climb here], a Spitfire would take about 23 minutes to cover the 70 miles from Duxford to Canterbury. It could take off about five minutes after the first radar warning of a build-up over Calais. A bomber travelling at 180 mph would reach Canterbury in 14 minutes. Even without adding in time for forming up, and assuming the Wing used Spitfires rather than the slower Hurricanes, which would take longer, a German bomber formation would be over Canterbury in half the time it would take a single fighter from Duxford to get there. The whole thing was absurd."

PO Tom Neil of 249 Sqn had this to say about the Big Wings, "All too frequently, when returning to North Weald in a semi-exhausted condition, all we saw of 12 Group's contribution to the engagement, was a vast formation of Hurricanes in neat vics of three, steaming comfortably over our heads in pursuit of an enemy who had long since disappeared in the direction of France. Our reactions on such occasions, though mostly of resigned amusement at first, grew to be more harshly critical later on."

There were pilots who were critical of the practice who took part in it, Flt Lt Douglas Blackwood of 310 Sqn stated that it was often chaos at the back of the formation with people being left behind, but Bader up front never saw that side of it. Another pilot, 19 Sqn's Frank Brinsden recalled that the Big Wings were a disaster that achieved nothing because they broke up during combat at any rate.




Thumpalumpacus said:


> And in my truck, cruise control is near-useless in traffic because I must consistently adjust throttle to "fly" with traffic. It's great on open highway when everyone is doing the same speed. It follows that I get better mileage driving an empty road than stop-and-go through a freeway jam.



Same in my V8 Commodore, smooth fuel consumption on the open road when I reach the engine's sweet spot, but in traffic around town it's a whore of a thing.

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## Thumpalumpacus (Jul 17, 2021)

FLYBOYJ said:


> If you maintain a V or finger 4. The Germans had a good technique (I think developed by Molders) where the wingman would move up while the lead tightened his turn, this was done simultaneously within a 4 plane formation.
> 
> View attachment 632579



I had larger escort formations in mind when I wrote that, and I should have made that plain. My apologies for not being as clear as I should have. And if I'm not understanding escort protocols right, that's on me. I'm thinking 24 fighters or so weaving above a formation of bombers. Am I missing something? Did sections stay in specific sectors over the bombers?


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## FLYBOYJ (Jul 17, 2021)

Thumpalumpacus said:


> I had larger escort formations in mind when I wrote that, and I should have made that plain. My apologies for not being as clear as I should have. And if I'm not understanding escort protocols right, that's on me. I'm thinking 24 fighters or so weaving above a formation of bombers. Am I missing something? Did sections stay in specific sectors over the bombers?


What I showed was just a basic maneuver for fighters, no apologies required. You got it right.

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## nuuumannn (Jul 17, 2021)

FLYBOYJ said:


> If you maintain a V or finger 4. The Germans had a good technique (I think developed by Molders) where the wingman would move up while the lead tightened his turn, this was done simultaneously within a 4 plane formation.



A _Kette_, which was based around the _Rotte_, which was a fighter and his wingman, two _Rotten_ made a _Kette_, [and two Ketten made a Litter ] which was eminently more flexible than, say the British Vic, which was cumbersome and required the guys inside to be throttling back while the guys on the outside would be powering up to maintain formation with the leader. I believe the British later adopted the Finger Four too. The Vic was adopted as the standard formation because a Vic of three made up a Section, of which two Sections made up a Flight and two Flights made up a Squadron.


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## Thumpalumpacus (Jul 17, 2021)

nuuumannn said:


> A _Kette_, which was based around the _Rotte_, which was a fighter and his wingman, two _Rotten_ made a _Kette_, [...]


 I got that from Caldwell's book on JG26, yeah.

I always loved the term _rottenfuhrer_ -- god knows I've had enough of those!

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## Shortround6 (Jul 17, 2021)

Thumpalumpacus said:


> I had larger escort formations in mind when I wrote that, and I should have made that plain. My apologies for not being as clear as I should have. And if I'm not understanding escort protocols right, that's on me. I'm thinking 24 fighters or so weaving above a formation of bombers. Am I missing something? Did sections stay in specific sectors over the bombers?


Drgondog would be the expert but my understanding is that the fighter formations did a series of S turns over the bombers to keep their airspeed up while remaining over or near the bombers. Trying to accelerate form bomber cruise speed to combat speed for fighters could take 2 or more minutes, at which time the attackers have come and gone.

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## nuuumannn (Jul 17, 2021)

Thumpalumpacus said:


> rottenfuhrer



"Herr Oberst, the Rottenfuhrer"

"Yes, I believe he is..."

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## Thumpalumpacus (Jul 17, 2021)

Shortround6 said:


> Drgondog would be the expert but my understanding is that the fighter formations did a series of S turns over the bombers to keep their airspeed up while remaining over or near the bombers. Trying to accelerate form bomber cruise speed to combat speed for fighters could take 2 or more minutes, at which time the attackers have come and gone.



Thanks for that. I think where my thinking might be faulty is whether all the fighters did a weave over the bomber formation, or whether fighter sections performed individual weaves over an assigned sector of the formation?


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## Milosh (Jul 17, 2021)

Iirc there was close escort and extended escort. The extend (not sure this is the correct word) flew some distance out in front of the bomber formation. The close escort, one group on each side and one trailing the bombers.

edit: this might have come one of the Mighty Eighth books

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## 33k in the air (Jul 17, 2021)

Thumpalumpacus said:


> Thanks for that. I think where my thinking might be faulty is whether all the fighters did a weave over the bomber formation, or whether fighter sections performed individual weaves over an assigned sector of the formation?



The document Development of the Long-Range Escort Fighter on pages 70, 93, and 119 has illustrations showing the way the escorts were positioned and flew.


ETA: There is also this from _Target Berlin_ regarding the 6 March 1944 mission (p.14):

_When fully assembled, the bomber stream for a large attack could be more than 90 miles long. Because they cruised somewhat faster than bombers and had to zig-zag to maintain station on them, individual fighter groups could not cover bombers for much more than 30 minutes at a time before fuel began to run low and they had to break away. As a result only a small proportion of the available escort fighters would be in position to cover bombers at any one time. On 6 March only rarely would there be more than 150 escorts in position; if these were distributed evenly along the length of the bomber stream there would be an average of only three fighters for every two miles of airspace. Such a split force would obviously have been ineffectual and easily overwhelmed by the enemy; so it was usual to position about a third of the fighters near the head of the bomber stream --- that part most vulnerable to head-on attack --- and distribute the remaining fighters in 8-aircraft units along the length of the stream. It was inevitable, therefore, that from time to time some combat wings would have no fighters covering them._

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## GregP (Jul 17, 2021)

I was assuming the drop tank got used up before engaging in combat, but it actually could happen any time. Good call.


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## pbehn (Jul 18, 2021)

nuuumannn said:


> A bomber travelling at 180 mph would reach Canterbury in 14 minutes. Even without adding in time for forming up, and assuming the Wing used Spitfires rather than the slower Hurricanes, which would take longer, a German bomber formation would be over Canterbury in half the time it would take a single fighter from Duxford to get there. The whole thing was absurd."


And on the other side of the coin, when Goering tried his first massed raids on London headwinds dropped the bombers speed down to around 110MPH which screwed up all calculations about escorting them. These headwinds gave the big wing time to form up and put in a spectacular late show.

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## drgondog (Jul 18, 2021)

33k in the air said:


> The document Development of the Long-Range Escort Fighter on pages 70, 93, and 119 has illustrations showing the way the escorts were positioned and flew.
> 
> 
> ETA: There is also this from _Target Berlin_ regarding the 6 March 1944 mission (p.14):
> ...


USAF Study 136 is probably the best source for Development and Tactics for evolving Fighter Escort as well as rich insight to the politics of AAC/AAF development of airpower in the 30's and early 40's.

As to Target Berlin narrative, Jeff glossed over the existing tactics as well as the issues confronted by the 8th AF Mission Planners. Consider that the March 6 Berlin attack was perhaps the simplest, namely 3 intact Bomb Divisions flying in-trail, relatively easy for individual fighter groups to find and escort their assigned boxes (within BD section of the long trail). You also get the impression that the LR escort FGs split into autonomous sections to more evenly distribute along the bomber stream. Nope - a squadron tasked to cover say, a box of 50 bombers would split into two sections to cover each other wile 'essing'. Only in very rare situations would sections be dispersed. The 56th FG Zemke Fan actually broke into flights and damn near lost Gp CO Zemke as a result.


NOTE: Summer 1943 brought distinctive Tail Markings (i.e "Triangle A" for 91st BG, "Square D for 100th Bomb Group) to make it easier (possible) to identify a specific Bomb Group - both for bomber crews and fighter squadrons searching for their flock.

There was no 'even distribution - ever. Particularly in January through April, the number of LR escort fighter groups (P-38J/P-51B) were combined (3Jan, 4 into Big Week, 7 for March 6-8 Berlin missions, 8 through mid April)

The 'math' was One FG per BD for Target escort until end of Big Week, Two FG through late April. If only one to three target areas were attacked. If the strike as complex with up to five task forces striking dispersed target areas, the available FG escort per Task Force was back to One.

Each BD was comprised of Multiple Combat Wings - each CBW with multiple BG, each with prominent Tail ID.

The lowest common denominators was the 'Box' usually several per BD and composed with two BG - one complete and one partial (i.e. The partial BG was usually one squadron from another group attached to the complete 4 squadron BG to get the box up to ~ 50 bombers. The reason was to ensure maximum compactness to shorten the length of the Task Force to get better concentration of bombs and make it easier to b 'found' and escorted.

Squadrons broke into sections for weave, in order to cover each other and to disperse to each side of the formation. Early in LR escort experience cycle, the squadrons took position and High Front, Center and Rear. Later High Center, sweep front and 'roving' side escort along the shoulder of the bomber formation believed most vulnerable to large scale attacks. 

What is the point? For Berlin, the task was relatively simple - Six total LR escort covered 90 miles of airspace, with one of the six (4th) splitting into one and two squadrons to sweep in front as well as provide high cover over the leading three boxes of the 1st BD/1st TF. The 354th provided three squadron coverage to 3rd BD/2nd TF. The three P-38 FGs provided rear box coverage to 2nd TF and Front/Rear coverage to 2nd BD/3rd TF.

LW put up 460 day fighters, Approximately 60% engaged from east of Frankfort - all along the bomber stream but most against the 1st and 2nd TF. 

Several of the 11 P-47 FGs providing Penetration escort were key to the 36-7-12 VC total. Of the LR escort the 3 P-38 FGs scored 3-0-1 while the 3 Mustang Groups scored 43-1-20

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## SaparotRob (Jul 18, 2021)

There are so many jewels buried in this thread. Thanks drgondog.

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## Glider (Jul 18, 2021)

I admit that I missed the bit where the P39 was considered. All sorts of options were in the paper including the 'fighter' B17 but no mention of the P39. Wonder Why?

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## SaparotRob (Jul 18, 2021)

Glider said:


> I admit that I missed the bit where the P39 was considered. All sorts of options were in the paper including the 'fighter' B17 but no mention of the P39. Wonder Why?


The YB-40 was a better fighter?

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## GrauGeist (Jul 18, 2021)

SaparotRob said:


> The YB-40 was a better fighter?


Yeah, it didn't have nose armor...

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## 33k in the air (Jul 18, 2021)

drgondog said:


> USAF Study 136 is probably the best source for Development and Tactics for evolving Fighter Escort as well as rich insight to the politics of AAC/AAF development of airpower in the 30's and early 40's.



Is that available online?



drgondog said:


> As to Target Berlin narrative, Jeff glossed over the existing tactics as well as the issues confronted by the 8th AF Mission Planners. Consider that the March 6 Berlin attack was perhaps the simplest, namely 3 intact Bomb Divisions flying in-trail, relatively easy for individual fighter groups to find and escort their assigned boxes (within BD section of the long trail).



To be fair though the book isn't about escort tactics. I wouldn't expect the kind of detail on the subject such as you related.


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## drgondog (Jul 18, 2021)

33k in the air said:


> Is that available online?


Lol - yes you posted the link above.


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## SaparotRob (Jul 18, 2021)

drgondog said:


> Lol - yes you posted the link above.


I think we’re all seeing double from this thread by now.

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## Thumpalumpacus (Jul 18, 2021)

33k in the air said:


> The document Development of the Long-Range Escort Fighter on pages 70, 93, and 119 has illustrations showing the way the escorts were positioned and flew.
> 
> 
> ETA: There is also this from _Target Berlin_ regarding the 6 March 1944 mission (p.14):
> ...



Thank you for the link and the excerpt. I've got family here now, so will fully read your link in the next day or two [ETA: I just saw it runs 333 pages. It might be more than a couple of days!]. 

But this is what I love about this forum, it's such a wealth of information. Much appreciated, brotha.



Milosh said:


> Iirc there was close escort and extended escort. The extend (not sure this is the correct word) flew some distance out in front of the bomber formation. The close escort, one group on each side and one trailing the bombers.
> 
> edit: this might have come one of the Mighty Eighth books



I remember reading something about it in Gerald Astor's oral history, _The Mighty Eighth_, but that was about three centuries ago, lol. It got confuzzled in my head.

Thank you both for the answers!

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## pbehn (Jul 18, 2021)

The conflict constantly evolved as most do, I found this on the Quora web site posted by Steven Rusling.

First, head on attacks. These were very difficult for anything but an experienced pilot. There was certainly no five second firing opportunity or use of rockets or aerial mortars (which were ‘stand off’ weapons to be fired from outside the range of the bombers’ defences).

Here’s an account of the problems associated with head on attacks from a man who flew them in real life, rather than on a computer game, and an explanation of why the tactic was attempted at all.

Fw. Fritz Ungar flew with JG 54 and JG 26, from August 1943 until the end of the war, and was credited with three bombers destroyed.

_“During an attack from behind, we were under defensive fire from the bombers too long, and at least three machine gun positions fired at us from each aircraft. In addition, the escorting fighters had the task of keeping us away from the bombers. We had no option but to attack from head on. Everything went very quick in this tactic. Every second brought us 220m closer together. Of course we didn’t want to collide, but pull away over the bomber. For this pulling up and over the bomber, one needed almost the whole last two seconds (=400m). Our guns were adjusted for 400m. Therefore we had two options: to fire too early, already at a distance of 600m or 500m, or to pull up half a second later. A very dangerous business. We didn’t have one second to fire our guns. It is incredible when one thinks of all the efforts we had to make for just one second. One thing was absolutely necessary: aim very precisely for this short moment.”_

The fighters did not go at the bombers as fast as possible either. They would manoeuvre for position, following initially their controller’s commentary and then the orders of the various commanders in the air. They would seek an opportunity to attack the bombers whilst evading the escorts. Later in the war, Luftwaffe ‘Jagdflieger’ became very wary of escort fighters and were sometimes reluctant to attack well escorted formations. The bombers’ defensive fire was certainly a factor, but there was never any hesitation about attacking unescorted bombers, it was the escort fighters that were the real problem.

Here is another Luftwaffe pilot, Oblt. Otto Stammberger, a Staffelkapitan with 4./JG 26 describing the defensive fire from the bombers.

_“Even under these relatively favourable circumstances_ [When an unescorted formation was intercepted]_ it was sheer murder to attack the American combat boxes from the rear, which we sometimes did in an effort to get more time to fire. This left us exposed to the defensive fire of the bombers for a longer time too. At a distance of some 1500m the US Viermots opened fire from all barrels. A bomber formation usually consisted of 20 machines, which flew in rows of four planes and were sideways echeloned, and in which these rows of four bombers were stacked on top of each other with row four and five flying in the middle. We normally opened fire at a distance of 300m and tried to close in to 30m or 40m. During all this time our fighters were subjected to the defensive fire of at least eight machine guns per bomber, which, with a group of 20 bombers, meant the concentrated fire of 160 machine guns…Opening fire from behind, at 300m distance, and taking us 5 or 6 seconds to overtake the bombers, these attacks were indescribable in their sheer physical and mental stress…We therefore changed tactics and started attacking from head on, which called for incredible dexterity, a good aim and nerves of steel until the last second.”_

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## nuuumannn (Jul 18, 2021)

Glider said:


> admit that I missed the bit where the P39 was considered. All sorts of options were in the paper including the 'fighter' B17 but no mention of the P39. Wonder Why?


What was this thread about again? 😁

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## nuuumannn (Jul 18, 2021)

SaparotRob said:


> The YB-40 was a better fighter?


Did the Russians love it?

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## drgondog (Jul 18, 2021)

pbehn said:


> The fighters did not go at the bombers as fast as possible either. They would manoeuvre for position, following initially their controller’s commentary and then the orders of the various commanders in the air. They would seek an opportunity to attack the bombers whilst evading the escorts. Later in the war, Luftwaffe ‘Jagdflieger’ became very wary of escort fighters and were sometimes reluctant to attack well escorted formations. The bombers’ defensive fire was certainly a factor, but there was never any hesitation about attacking unescorted bombers, it was the escort fighters that were the real problem.
> 
> Here is another Luftwaffe pilot, Oblt. Otto Stammberger, a Staffelkapitan with 4./JG 26 describing the defensive fire from the bombers.
> 
> _“Even under these relatively favourable circumstances_ [When an unescorted formation was intercepted]_ it was sheer murder to attack the American combat boxes from the rear, which we sometimes did in an effort to get more time to fire. This left us exposed to the defensive fire of the bombers for a longer time too. At a distance of some 1500m the US Viermots opened fire from all barrels. A bomber formation usually consisted of 20 machines, which flew in rows of four planes and were sideways echeloned, and in which these rows of four bombers were stacked on top of each other with row four and five flying in the middle. We normally opened fire at a distance of 300m and tried to close in to 30m or 40m. During all this time our fighters were subjected to the defensive fire of at least eight machine guns per bomber, which, with a group of 20 bombers, meant the concentrated fire of 160 machine guns…Opening fire from behind, at 300m distance, and taking us 5 or 6 seconds to overtake the bombers, these attacks were indescribable in their sheer physical and mental stress…We therefore changed tactics and started attacking from head on, which called for incredible dexterity, a good aim and nerves of steel until the last second.”_


Egon Meyer was generally credited with developing and leading the first 'head on attack' in November 1942. Adolph Galland improved on it by instructing the attacking Fw 190 pilots to Not Split Ess - but to pass through the formation to recover, turn, pace and regain Rotte/Stafel size force to repeat. His comments (valid) were to the effect that the dive away required too much fuel and time to rejoin the B-17 formations. 

While successful, the tactic required great skill by the leader as well as the entire force to hold steady for makeable shots to the frontal area of the target bomber.

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## Just Schmidt (Jul 18, 2021)

GrauGeist said:


> Then you proceed to ignore the peer reviewed, manufacturer's, military's and actual pilot's information and proceed to post flawed, skewed, cherry-picked or imaginary information/data over and over and over and over and over and over and over and over and over and over and over...


Thank you for making me realize how long it was since last I listened to this:



Groundhog threads do have many uses...

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## pbehn (Jul 18, 2021)

drgondog said:


> Egon Meyer was generally credited with developing and leading the first 'head on attack' in November 1942. Adolph Galland improved on it by instructing the attacking Fw 190 pilots to Not Split Ess - but to pass through the formation to recover, turn, pace and regain Rotte/Stafel size force to repeat. His comments (valid) were to the effect that the dive away required too much fuel and time to rejoin the B-17 formations.
> 
> While successful, the tactic required great skill by the leader as well as the entire force to hold steady for makeable shots to the frontal area of the target bomber.


Agreed Bill, it wasnt my post I found it somewhere else, I thought it interesting because it discusses how tactics changed from the people involved.

Some pilots and squadrons favoured head on attacks in the BoB. Some have equated the RAF "Big Wing" idea to the massed "company front" attacks of the LW. They had the same basic idea to deliver a massive blow with a combined simultaneous attack, and the solution for US air forces was what Galland wanted to do in the BoB, to sweep ahead of the bombers to catch LW fighters climbing, forming up and attacking.


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## 33k in the air (Jul 18, 2021)

drgondog said:


> Lol - yes you posted the link above.



LOL sorry, I misread your post and thought you were referring to a different document. D'Oh!

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## P-39 Expert (Jul 18, 2021)

My bomber escort calculations are correct.

Read the directions in the pilot's manual and use the Flight information Instruction Chart, everything you need is in that chart. You don't need any other reference. There were four segments to an escort mission, takeoff and climb (20gal per the chart), combat for 20min, landing reserve 20min, with the rest of the fuel used for cruising.

Reserve for combat isn't based on 147gph, combat would take place at 25000' or so. Fuel burn at 25000' was 62gph at 2600rpm (normal power). Combat power was 3000rpm, I'm estimating 72gph so 20min would be 24gal. Plane would still climb at almost 2000fpm at 25000', phenomenal performance when compared to other fighter planes in 1943. 

Early N models had the normal 120gal internal fuel, kits were available to convert 87 gallon models back to 120gal. 110gal drop tanks were common on 8th AF fighter bases during that period. 110gal tanks were also used extensively by P-39s in the Pacific.

20 minute reserve for landing is what I have always heard. If you want to use 30gal reserve fine, use that. Navy used a 60 minute reserve, but their pilots had to find an aircraft carrier to land on. In any case a landing reserve was needed in case the base was closed by weather or the pilot was lost.

Escort pilots were strongly encouraged to bring the drop tank back, they cost money like everything else. There were 110gal paper tanks also, but they were only good for one mission. If combat came before the fuel was exhausted in the drop tank, they the mission was abbreviated, just like any fighter that carried a drop tank.


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## GregP (Jul 18, 2021)

The 20 gallons you are using is takeoff and climb to 5,000 feet, Expert. Read the chart, for crying out loud. Also, that test was NOT a stock P-39N. It was flown at 7,274 pounds. The pilot's manual for a P-39N, with the ammunition on board and no extra drop tank comes in at 7,517 pounds (again, with ammunition and without drop tank). Without the drop tank, the range is utterly useless.

A stock P-39N has a 1,200 hp engine with takeoff at 50.5 " MAP and 1,125 hp WER at 44.5" MAP. The report is a test using 59.8" MAP and 1,420 hp that was not released for squadron use. So, you are again cherry picking at an advanced level.

Say you were actually flying a stock P-39N, and you take off and climb to 5,000 feet with your 20 gallons of fuel and you allow for 10 minutes combat at 135 gallons per hour. That leaves you just 44.5. minutes of cruising at 255 mph at 6,000 feet (I let you magically climb 1,000 feet with no fuel burn). Counting the distance traveled in climb and the 44.5 minutes at 255 mph, your range is just under 100 miles ... not really of much use. At 7,500 pounds and 25,000 feet, a stock P-39N can climb at about 1,250 feet per minute assuming it is at Emergency Power. It could climb at 1,100 fpm if at normal power.

For comparison, a Spitfire Mk V in 1941, a year earlier than your high horsepower P-39 test you are looking at just in case you aren't looking at dates, was climbing at 1,940 fpm at 23,000 feet. And it didn't have any issues with C of G, nose armor, or car doors that needed to be opened to bail out. Plus it was in widespread use by the British, something the P-39N wasn't.

But, I'm sure you would KNOW this if you read the test report and also looked at the manual for the service airplanes with an unbiased eye.

You certainly do like the airplane. Perhaps not without some justification. It wasn't a BAD fighter until it ran across an enemy fighter at an altitude above 12,000 feet or so that was closer to home than about 170 miles. Then it was less than wonderful. Of course, you really wouldn't be running into an enemy fighter farther away from home than about 170 miles anyway or you'd run out of fuel getting home. A Spitfire Mk Vb was considered a short ranged and it could travel over 1,100 miles, making for a combat range of half that, or about 550 miles. You'd need more than twice the P-39's range just to be considered a "short range fighter!" But, hey, you could intercept low-altitude enemies over London as long as you kept a close eye on the fuel gauge. A great point-defense or short-range attack, low-altitude fighter, and that is a niche that the Russian exploited.

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## Shortround6 (Jul 18, 2021)

P-39 Expert said:


> Using a P-39N with 120gal internal and 110gal drop tank (230gal) deduct 20gal for takeoff and climb,


That gets you to 5000ft, switch to drop tank is probably a bit earlier.


P-39 Expert said:


> 25gal for 20min combat at 25000' and


actually about 40 gallons would be a better estimate.


P-39 Expert said:


> 10gal for 20min landing reserve at 5000'.


Going to loose a lot planes looking for airfields, an extra 5 gallons might be to your advantage.


P-39 Expert said:


> The remaining 175gal (cruise) is divided by 62gallons per hour giving a flight time of 2.8hrs multiplied by 276mphTAS = 772mi.


Doesn't work that way unless you want an lot of planes running out of gas.
Drop tank does* not* count for combat (especially a 110 gallon tank) and does not count for return flight.
You have 60 gallons or less internal fuel for the trip back.
Every other escort fighter was figured as internal fuel minus take-off allowance, minus reserve for "landing/finding field" and combat allowance.
only reason the P-39 looks good for fuel consumption is because it isn't making enough power.



P-39 Expert said:


> Reserve for combat isn't based on 147gph, combat would take place at 25000' or so. Fuel burn at 25000' was 62gph at 2600rpm (normal power). Combat power was 3000rpm, *I'm estimating 72gph so 20min would be 24gal. *Plane would still climb at almost 2000fpm at 25000', phenomenal performance when compared to other fighter planes in 1943.



You estimate wrong. You have been told this before. 

going from 2600rpm to 3000rpm is a about a 15% increase in RPM. Since internal friction goes up with the square of the speed (RPM) that is a 33% increase in power lost to internal friction. Guess what? the power to turn the supercharger impeller goes up with the square of the speed, another 33% increase in power required just to turn 3000rpm.
Where does this power come from?
Pixie dust?
Unicorn Poop? 
Satanic rituals? 
Groundhog mystical incantations? 

Try more fuel burned in the cylinders to get the power at the Propshaft measured in lbs/hp/hr. 

A much closer estimate would be the amount of fuel needed at 15,500ft for military power divided by the fuel burned for that power,(1125hp divided by 138 gallons equals 8.15 hp per hour per gallon). then find the power at 25,000ft and divide by 8.15. (770 hp divided by 8.15 equals 94.47 gallons and hour) or 31.17 gallons for 20 minutes. 
However that is *ONLY *if the P-39 can remain at 25,000ft. If it is forced to trade altitude for speed at any point and descends to 20,000ft the with the engine still doing 3000rpm and the throttle still wide open it will make about 910 hp and the fuel burn will go to 111.65 gallons per hour (or 1.86 gallons per minute.) 

The phenomenal performance actually looks pretty crappy compared to P-38G or a Spitfire VIII or even a Spitfire IX. 

Or even a MK IX Spit with a 30 imp gallon tank still attached. 

Sorry, 370mph or so at 25,000ft just isn't good enough.

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## 33k in the air (Jul 19, 2021)

P-39 Expert said:


> Read the directions in the pilot's manual and use the Flight information Instruction Chart, everything you need is in that chart. You don't need any other reference. There were four segments to an escort mission, takeoff and climb (20gal per the chart), combat for 20min, landing reserve 20min, with the rest of the fuel used for cruising.



Read the *Take-Off, Climb, and Landing Chart* on page 26.

*Climb Data*
8,000 lbs (combat): sea level to 25,000 feet: 13.9 minutes; 39.7 gallons fuel consumed from sea level
7,500 lbs (combat): sea level to 25,000 feet: 10.8 minutes; 35.3 gallons fuel consumed from sea level
7,100 lbs (combat): sea level to 25,000 feet: 9.9 minutes, 34.0 gallons fuel consumed from sea level

Note that the above fuel consumption figures include warm-up and take-off allowance.



P-39 Expert said:


> Escort pilots were strongly encouraged to bring the drop tank back, they cost money like everything else. There were 110gal paper tanks also, but they were only good for one mission. If combat came before the fuel was exhausted in the drop tank, they the mission was abbreviated, just like any fighter that carried a drop tank.



If you get into a fight, the drop tanks are immediately released. Carrying them into combat means extra drag (and weight) on the aircraft, reducing performance. There's also the danger of fire if the drop tank is not self-sealing. 

The 108-gallon paper tank was widely used in the ETO because these were cheap to manufacture and used material which was of no benefit to the enemy if dropped over enemy territory. They were also quite a bit lighter than metal tanks. The metal 110-gallon tank was far less common. (There were actually two 110-gallon metal drop tanks: one cylindrical and one tear-drop shaped which came into use later. It had better aerodynamics than the cylindrical version.)

I have seen a photo of a P-39 sporting the 150-gallon 'flat' drop tank created for the P-47. I don't know if the P-39 ever carried that particular type of tank into combat.

Again, the combat radius is determined by how far the aircraft can go on internal fuel after deducting the fuel set aside for combat, reserve fuel, warm-up, take-off, and initial climb.

120 gallons won't take you far after the appropriate deductions are made.

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## FLYBOYJ (Jul 19, 2021)



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## 33k in the air (Jul 19, 2021)

Shortround6 said:


> That gets you to 5000ft, switch to drop tank is probably a bit earlier.



The switch was made at about 1,000 feet --- at least that's what I remember reading for P-51s.


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## buffnut453 (Jul 19, 2021)

I wonder if this book has any useful performance figures?

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## FLYBOYJ (Jul 19, 2021)

"landing reserve" I did a quick word search in the manual and several flight training handbooks, I cannot find that term. Can anyone else point me in the direction where I can find a definition of that term?


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## FLYBOYJ (Jul 19, 2021)

Shortround6 said:


> Where does this power come from?
> Pixie dust?
> Unicorn Poop?
> Satanic rituals?
> *Groundhog mystical incantations?*

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## fubar57 (Jul 19, 2021)

FLYBOYJ said:


> "landing reserve" I did a quick word search in the manual and several flight training handbooks, I cannot find that term. Can anyone else point me in the direction where I can find a definition of that term?


In my copy its under the third groundhog on the right

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## GrauGeist (Jul 19, 2021)

FLYBOYJ said:


> "landing reserve" I did a quick word search in the manual and several flight training handbooks, I cannot find that term. Can anyone else point me in the direction where I can find a definition of that term?


All the information you need can be found in "Never Never land".

nev·er-nev·er land

_noun_
noun: *never-never land*

an imaginary utopian place or situation.

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## wuzak (Jul 19, 2021)

FLYBOYJ said:


> "landing reserve" I did a quick word search in the manual and several flight training handbooks, I cannot find that term. Can anyone else point me in the direction where I can find a definition of that term?



I think he means the reserve fuel which is, of course, not just for landing.

I would have thought that the actual landing would not use a lot of fuel, since gravity is helping that process!

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## FLYBOYJ (Jul 19, 2021)

wuzak said:


> I think he means the reserve fuel which is, of course, not just for landing.
> 
> I would have thought that the actual landing would not use a lot of fuel, since gravity is helping that process!


Yep! Gravity does save fuel! LOL!

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## pbehn (Jul 19, 2021)

P-39 Expert said:


> Read the directions in the pilot's manual and use the Flight information Instruction Chart, everything you need is in that chart. You don't need any other reference. There were four segments to an escort mission, takeoff and climb (20gal per the chart), combat for 20min, landing reserve 20min, with the rest of the fuel used for cruising.
> 
> Reserve for combat isn't based on 147gph, combat would take place at 25000' or so. Fuel burn at 25000' was 62gph at 2600rpm (normal power). Combat power was 3000rpm, I'm estimating 72gph so 20min would be 24gal. * Plane would still climb at almost 2000fpm at 25000', phenomenal performance when compared to other fighter planes in 1943. *


The Spitfire Mk IX entered service in 1942 rate of climb with 66 Merlin at 30,000ft 2,125ft/min with Merlin 70 2,600ft/min

Test in Oct 1942 Spitfire Mk IX Performance Trials

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## fubar57 (Jul 19, 2021)

Quit bringing up facts, they ruin the thread

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## pbehn (Jul 19, 2021)

fubar57 said:


> Quit bringing up facts, they ruin the thread


I am looking for the word above "phenomenal".


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## fubar57 (Jul 19, 2021)

I myself just looked up the word "parsimonious" for no other reason than it was used prodigiously in a National Lampoon story back in 1973 and I finally got around to finding out what it means

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## GregP (Jul 19, 2021)

A landing reserve is a large plot of ground where airplanes can take off and land.

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## XBe02Drvr (Jul 19, 2021)

wuzak said:


> I would have thought that the actual landing would not use a lot of fuel, since gravity is helping that process!


Gotta have enough for a bolter or three.

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## pbehn (Jul 19, 2021)

Did anyone consider using the engine from a P-39N in a P-51B? Phenomenal performance and only a third of the fuel consumption in combat.

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## XBe02Drvr (Jul 19, 2021)

GrauGeist said:


> _noun_
> noun: *never-never land*
> 
> an imaginary utopian place or situation.


2. indigenous name for the albatross, which according to legend is capable of soaring perpetually, thus never needing to come down to earth.

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## Shortround6 (Jul 19, 2021)

pbehn said:


> Did anyone consider using the engine from a P-39N in a P-51B? Phenomenal performance and only a third of the fuel consumption in combat.








OK, they didn't stick it in a "B" airframe


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## pbehn (Jul 19, 2021)

Shortround6 said:


> View attachment 632790
> 
> 
> OK, they didn't stick it in a "B" airframe


Wow, what was it called?

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## Peter Gunn (Jul 19, 2021)

FLYBOYJ said:


> "landing reserve" I did a quick word search in the manual and several flight training handbooks, I cannot find that term. Can anyone else point me in the direction where I can find a definition of that term?


I think this guy might be able to help you:

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## gordonm1 (Jul 19, 2021)

Too many pages to keep up...

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## Peter Gunn (Jul 19, 2021)

Shortround6 said:


> Drgondog would be the expert but my understanding is that the fighter formations did a series of S turns over the bombers to keep their airspeed up while remaining over or near the bombers. Trying to accelerate form bomber cruise speed to combat speed for fighters could take 2 or more minutes, at which time the attackers have come and gone.


I believe you are correct, also 

 drgondog
once told me that every 40-50 minutes the Mustangs would rev up to even higher RPM's for several minutes to keep the plugs from fouling.

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## WARSPITER (Jul 20, 2021)

fubar57 said:


> Quit bringing up facts, they ruin the thread



Yeah - I prefer the fluffy pictures of the P39 in winter camo......

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## MikeMeech (Jul 20, 2021)

Peter Gunn said:


> I believe you are correct, also
> 
> drgondog
> once told me that every 40-50 minutes the Mustangs would rev up to even higher RPM's for several minutes to keep the plugs from fouling.


Hi
The plugs were one of several problems that arose with the introduction of the P-51B, it appears to have been 'solved' by using British RC5/5 plugs instead of the original ones. There is a good summary of the various problems, and 'solutions', in 'The Mighty Eighth War Manual' by Freeman, pages 195-196, extracts below:














Mike

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## P-39 Expert (Jul 20, 2021)

GregP said:


> The 20 gallons you are using is takeoff and climb to 5,000 feet, Expert. Read the chart, for crying out loud. Also, that test was NOT a stock P-39N. It was flown at 7,274 pounds. The pilot's manual for a P-39N, with the ammunition on board and no extra drop tank comes in at 7,517 pounds (again, with ammunition and without drop tank). Without the drop tank, the range is utterly useless.
> 
> A stock P-39N has a 1,200 hp engine with takeoff at 50.5 " MAP and 1,125 hp WER at 44.5" MAP. The report is a test using 59.8" MAP and 1,420 hp that was not released for squadron use. So, you are again cherry picking at an advanced level.
> 
> ...


Not a "stock" P-39N for the Wright Field test? Of course it was, it was taken straight from the production line. We've been over the test weights many times before, the quoted figure represents the average weight of the plane during a flight accounting for fuel burn. Virtually all the Wright Field tests used this method to compute weights for tests for all AAF fighter types. Their test weights were lower than published gross weights.

You're comparing takeoff power at SL and WEP at 9500' and it certainly was available for squadron use. 

In comparison with a Spitfire V the normal P-39 held 20% more internal fuel. There is no way on this earth that a Spitfire V had a combat radius of 550mi. Escort fighter bases in England were only 520mi from Berlin. Most escort range charts credit the Spitfire V with a combat radius of 175mi. Barely across the English Channel. 

Somebody certainly is "cherry picking" and it's not me.


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## pbehn (Jul 20, 2021)

P-39 Expert said:


> Not a "stock" P-39N for the Wright Field test? Of course it was, it was taken straight from the production line. We've been over the test weights many times before, the quoted figure represents the average weight of the plane during a flight accounting for fuel burn. Virtually all the Wright Field tests used this method to compute weights for tests for all AAF fighter types. Their test weights were lower than published gross weights.
> 
> You're comparing takeoff power at SL and WEP at 9500' and it certainly was available for squadron use.
> 
> ...


Where do you get your fuel consumption figures from for cruising at 25,000ft with a 110 gal tank? A 75 gal tank knocks 40 MPH off all cruising figures as per the tests. Could a P-39 actually get to and cruise at 25,000ft with all the fuel you want on it?

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## drgondog (Jul 20, 2021)

MikeMeech said:


> Hi
> The plugs were one of several problems that arose with the introduction of the P-51B, it appears to have been 'solved' by using British RC5/5 plugs instead of the original ones. There is a good summary of the various problems, and 'solutions', in 'The Mighty Eighth War Manual' by Freeman, pages 195-196, extracts below:
> View attachment 632888
> 
> ...


Roger Freeman did well on the narrative regarding the P-51B in general, but incorrect on several points:
1. Malcolm Hoods were being installed on Mustang III (P-51B-15-NA 'FZ100') which arrived in October but transferred to 9th and 8th AF in December in a Reverse Lend Lease from RAF. Substantial part of kits for Malcolm Hood model for P-51B went to BAD2 Warton, and when more kits were available, were released to Service Groups located around the fighter bases. Priority was to squadron/group leaders but many had filtered to the 'general pool' by May 1944.
2. The 358th FG was Assigned to and began operations with the 8th AF December/January but swapped for 357th FG.
3. Arnold prioritized P-51B/C for 8th AF in August 1943, but Leigh-Mallory leading TAC which included 9th AF took 'exception' to 354th (and succeeding 357th and 363rd and 339th) being assigned in 'any role' not under his command. Took Spaatz/Arnold/Portal to sort out the TDY assignments of 354 and 363 to 8th AF until Invasion preparation at end of May. Also to effect the trade of the P-7D equipped 358FG for the P-51B equipped 357FG ad re-assign the 339FG in return for the P-38 equipped 367FG.
4. The 0.50 cal four gun mount scheme/design for P-51B/C was Exactly the same as the A-36/P-51A.. The jamming problems and solution were as described by Freeman.
5. The engine mount bolt failure was due solely to QA from subcontractor - failure to properly heat treat the finished bolt to high tensile (90,000+ psi) strength. The Brits quickly secured a supply meeting NAA specs, NAA solved the problem and shipped to ETO a backload reserve as the production line was inspected and bolts replaced at the factor. The grounding order was lifted i three days.
6. The notion that a 'few' P-51Bs were sent to 20th and 55th (also 364th) P-38 FGs for conversion in July implies that a 'flood' of P-51Ds were available and that the P-38FGs ere getting 'hand me downs'. No, by Mid July only 300+ P-51D-5-NA had been delivered to ETO, compared to 1200+ operational P-51B/C in ETO. Brand new P-51Bs and Cs were still arriving in August-September 1944. His comment regarding 'small portion' being installed on P-1B/C was technically correct for the number of B/Cs produced - but all Malcolm kits went to ETO based Mustangs - zero for MTO/CBI/CONUS.

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## P-39 Expert (Jul 20, 2021)

Shortround6 said:


> That gets you to 5000ft, switch to drop tank is probably a bit earlier.
> 
> actually about 40 gallons would be a better estimate.
> 
> ...


Switch to drop tank is a lot earlier, right after gear and flaps up and climb speed has been established. Most of the fuel used on the ground and during takeoff will drain back into the main internal tanks. Most of the 20gal takeoff/climb allowance is used climbing toward the target and is therefore used in the range calculations.

Of course drop tank does not count for combat, the reserve for combat has already been deducted from the fuel total. Calculation is based on using the drop tank during climb and the outbound leg of the mission. The range calculation assumes that the tank remains in place on the return leg while internal fuel is being burned since cruising speed was not increased when the tank was dropped. Pilots were encouraged to bring the tank back if possible if no combat had been encountered. Otherwise pilots would have simply dropped the tank when the fuel was exhausted and the tank could not have been reused. Naturally if combat is encountered before the fuel was exhausted in the drop tank then the tank would be jettisoned and combat radius would be decreased. This is true of any plane carrying drop tanks, not just the P-39. Remember the P-39N cruising speed at 25000' without the drop tank was 350mph at the same power setting (2600rpm normal power) instead of 276mph with the tank. If combat is encountered the drop tank is dropped and the combat reserve (24gal) and the landing reserve (10gal) would be deducted from the 120gal internal fuel leaving 86gal to get home. 86gal divided by 62gph = 1.4hr x 350mph = 485mi, well over the combat radius quoted in the calculation. 

Regarding my estimate for fuel burn at combat power vs normal power, you are correct that going from 2600rpm to 3000rpm is about a 15% increase. That's the increase in fuel burn that I used for my estimate. Throttle setting was the same (full), mixture setting was the same (auto rich), plane was well above critical altitude. Only difference was rpm. You are entitled to your estimate, but that doesn't make it correct. Let's say that your estimate is correct at 31gal. vs my estimate of 24gal. Those 7 gallons represent 7 minutes less flying time (7 divided by 62gph) and 31mi at cruising speed (7 min x 276mph). That reduced combat radius by 16 whole miles. Hardly relevant at all. 

Compared to a P-38G the P-39N climbed a good bit better up to 25000' and was about the same speed up to 20000'. P-39N was well matched with contemporary 109s and 190s they would have encountered in early 1943. And nothing climbed with a Spitfire IX. Nothing.

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## Shortround6 (Jul 20, 2021)

pbehn said:


> Where do you get your fuel consumption figures from for cruising at 25,000ft with a 110 gal tank? A 75 gal tank knocks 40 MPH off all cruising figures as per the tests. Could a P-39 actually get to and cruise at 25,000ft with all the fuel you want on it?


 Nope, 

At least at a speed that would be considered useful. 

The escort fighters cruised at whatever speed, (within reason) that would get the job done. 
about 315mph true was what the nominal (chart) radius figures was based on. Does not include the S turns/weaving. 
Some missions they may have cruised slower.
However the escorts did have to cruise at a high enough speed so they could quickly respond to the German attackers. 
Cruise too slow and the escorts took too long to get up to a speed useful for combat. 

Here is where the P-39 is really going to suck. 

There are a couple of charts at the back of AHT that compare the acceleration (calculated) of the 8 major American fighters. The calculations are for 250mph starting speed and for sea level. One chart/table is for early versions using military power and the other is for late versions using combat power. The P-39 is in 4th place on both tables and in the early table is not behind the leaders by very much, only about 10% behind the champ (P-38F) of the early planes. 
However that is comparing a P-38F with two 1150 hp engines to a P-39D with one 1150 hp engine.
At 25,000ft the P-38 still has at least 1000hp per engine while the P-39 is done near 700HP? 

The later chart show things much wider apart. 
While the P-38L is now about 15% better than the 1420hp P-39Q-1 it's two 1600hp engines let it accelerate about 80% faster than earlier P-38F. 

_this is at sea level._

At 25,000ft the P-38L still has two 1600hp engines. The P-39 has an under 800hp engine, in fact nearer to 750hp. What is it's acceleration now? 
The P-47s have 1900 hp engines at 25,000ft in 1943, they get better later. 
The Merlins in the P-51Bs have 1410hp available in the mid 20,000ft range. Granted they are not available in in 1943. 

The P-39N could _eventually _get up to a useful speed but by then the attackers would be gone. 
It is not fast enough even at top speed (at 25,000ft) and once it does anything except fly straight and level either speed falls off or the plane looses altitude. 

The expert has made much of the P-39s climb rate. However max climb rate is done at 216mph at 25,000ft. 
Test of a P-47D in Aug 1943 show 1900hp available for climb at 25,000ft. Best climb speed is 246mph. 
Once both planes stop climbing the P-47 is flying about 30mph faster and despite it's weight and drag (which is not double that of the P-39) it's 2 1/2 times greater power is going to allow it better acceleration. The P-47 is about 30-40mph faster at top speed. 
IF both planes are doing 370mph at 25,000ft the P-39 is pretty much maxed out (assuming the test results reflect real world conditions) while the P-47 has the extra power needed to go 30-40mph faster in reserve to help it climb slowly or to compensate for a slight bank/gentile turn.

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## Shortround6 (Jul 20, 2021)

P-39 Expert said:


> Most of the 20gal takeoff/climb allowance is used climbing toward the target and is therefore used in the range calculations.


This works ONLY if your escort fighters arrive over the bomber stream and in enemy territory strung out in a line in the order they took off. If you actually want to form up into flights or squadrons it does not work. The AAC planners did not count the climb for range calculations, you have been told this many times. 


P-39 Expert said:


> Naturally if combat is encountered before the fuel was exhausted in the drop tank then the tank would be jettisoned and combat radius would be decreased.


Which really sucks if you are the fighter pilot/s you just had their radius decreased in mid flight. That translates into POW. 


P-39 Expert said:


> That's the increase in fuel burn that I used for my estimate.


It's wrong unless you can repeal the laws of physics.

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## pbehn (Jul 20, 2021)

Shortround6 said:


> It's wrong unless you can repeal the laws of physics.


As you pile on internal and external fuel and go higher, this mythical beast becomes more economical and faster, even my dear old grandmother would raise an eye brow at the proposition, it sounds like perpetual motion.

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## pbehn (Jul 20, 2021)

P-39 Expert said:


> Regarding my estimate for fuel burn at combat power vs normal power,


At 25,000ft there is no difference between the different types of power, because the engine could not develop enough power to trouble the bearings or any other component. This can be seen in the tests.

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## FLYBOYJ (Jul 20, 2021)

Hmmm - "*combat power* vs normal power"

Word search no such thing...

"Military Power/ Takeoff Power" found in manual.


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## drgondog (Jul 20, 2021)

P-39 Expert said:


> Not a "stock" P-39N for the Wright Field test? Of course it was, it was taken straight from the production line. We've been over the test weights many times before, the quoted figure represents the average weight of the plane during a flight accounting for fuel burn. Virtually all the Wright Field tests used this method to compute weights for tests for all AAF fighter types. Their test weights were lower than published gross weights.


No. Test weights stated are Always GW before takeoff. 

Conditions including taped gun ports, removal of sway braces, external tank/no tank. The Test weights Were mostly conducted Under combat weights - and as such Optimistic'. Major Price was the Wright Field Bell project officer and notorious for producing 'optimistic' reports. I draw your attention to comparisons of RAF test results to Wright and Bell tests.

P-39 Performance Tests

Looking at Op manual for P-39Q and 75 gal external tank, a couple of entries stand out, beginning on pg 24:

GW for stated FERRY combat load (full internal load of fuel plus 75 gal tank but ZERO 50 cal ammo) = 8,100 (of which the wt of tank/fuel & sway brace =800). Not stated but with full ammo, 330 pounds (1000 rnd), The P-39Q could only take off with 75gal external if 55 less gallons of fuel (or ammo) carried - in which case - leave the 75 gal tank at home. 
All Ranges stated are Ferry type profiles, with Maximum range =1000 miles for P-39Q-1 at 8100 GW.
Data above 15000 feet are left 'blank', save Condition II -->20K cruise settings of 30"MP, 2600rpm and IAS of 179mph/TAS and 76 gpm for Cruise.
The Optimal Cruise for distance is at 14,000 feet at 32"MP, 2280RPM and 74mpg (Clean)

There are no service ceilings published for 75 gal tank, nor is any data provided above 20K. Any proof that escort of any type was possible at 25K??

Note also that the fuel allowance for warm up, takeoff and climb to 20K consumes 42 gal.

In the escort role, there is no provision for forming up, nor consideration that when the P-39 actually reached 20K, that the TAS per the tables with 75 gal tank is 179IAS/270mph TAS was adequate to support US Heavies at 20K. - Well above FTH and Extremely sluggish to throttle up airspeed to deflect attacks. About the same speed as a fully loaded B-24 at 20,000 feet (cruise =170 to 180mph IAS).

The worst part of this ad-nauseum rendition of the 'super escort' P-39 (any production version) is that you never think to compare Wright Field/Bell test data with RAF test data - folks that REALLY needed a suitable fighter

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## FLYBOYJ (Jul 20, 2021)

For the sake of discussion here are the charts. Colors were added by me.
















*LET THE GROUNDHOGGERY BEGIN!*

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## FLYBOYJ (Jul 20, 2021)

Here are the charts for the P-39Q

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## Peter Gunn (Jul 20, 2021)

FLYBOYJ said:


> *SNIP*
> 
> *LET THE GROUNDHOGGERY BEGIN!*


Are you sure it isn't GROUNDH*U*GGERY? We are talking P-39 here...

Don't give me a P-39
The one with the engine behind

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## Peter Gunn (Jul 20, 2021)

drgondog said:


> *SNIP*
> 
> The worst part of this ad-nauseum rendition of the 'super escort' P-39 (any production version) is that you never think to compare Wright Field/Bell test data with RAF test data - folks that REALLY needed a suitable fighter


There are a few problems with this statement. First of all, we _*KNOW*_ that the evil Brits were conspiring to kill the P-39 what with their demands to add weight to it for no apparent reason (just for starters), so data from RAF not trustworthy.

Second, it's doubtful that the evil Brit RAF were using anything other than just "Joe Pilots" to run their P-39 program to heighten the sabotage of the Bell super plane, so again, data not trustworthy.

My God man, have you learned NOTHING in this thread?

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## Peter Gunn (Jul 20, 2021)

P-39 Expert said:


> Switch to drop tank is a lot earlier, right after gear and flaps up and climb speed has been established. Most of the fuel used on the ground and during takeoff will drain back into the main internal tanks. Most of the 20gal takeoff/climb allowance is used climbing toward the target and is therefore used in the range calculations.
> 
> Of course drop tank does not count for combat, the reserve for combat has already been deducted from the fuel total. Calculation is based on using the drop tank during climb and the outbound leg of the mission. The range calculation assumes that the tank remains in place on the return leg while internal fuel is being burned since cruising speed was not increased when the tank was dropped. Pilots were encouraged to bring the tank back if possible if no combat had been encountered. Otherwise pilots would have simply dropped the tank when the fuel was exhausted and the tank could not have been reused. Naturally if combat is encountered before the fuel was exhausted in the drop tank then the tank would be jettisoned and combat radius would be decreased. This is true of any plane carrying drop tanks, not just the P-39. Remember the P-39N cruising speed at 25000' without the drop tank was 350mph at the same power setting (2600rpm normal power) instead of 276mph with the tank. If combat is encountered the drop tank is dropped and the combat reserve (24gal) and the landing reserve (10gal) would be deducted from the 120gal internal fuel leaving 86gal to get home. 86gal divided by 62gph = 1.4hr x 350mph = 485mi, well over the combat radius quoted in the calculation.
> 
> ...


Yeeeaaaaah...

I still don't think you get the whole "range" and "mission planning" thing let alone the mission profile for deep penetration escort.

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## pbehn (Jul 20, 2021)

FLYBOYJ said:


> Hmmm - "*combat power* vs normal power"
> 
> Word search no such thing...
> 
> ...


In flight test reports here P-39 Performance Tests there is Normal rated power, Military power and War emergency power and the critical altitudes these were at, for level speeds and climb, this sort of stuff isnt my "bag" which is why I was asking where he got his info. I am pleased to see from other posts the laws of physics also apply to the P-39.

I would also say I have noticed in that test, they are very specific about the propeller used, and in the list of variants (below) there seems to have been many different ones, different numbers, different diameters even a 4 blade type. Bell P-39 Airacobra - U.S.A.A.F. Resource Center - A Warbirds Resource Group Site In the tests mentioned they quote different design numbers, diameter and even the blade angle range in one case. There is absolutely no way a test pilot knows what the implication of this is unless he is told by someone who does.






Bell P-39 Airacobra - U.S.A.A.F. Resource Center - A Warbirds Resource Group Site


This page deals with various technical aspects of the Bell P-39 Airacobra.




warbirdsresourcegroup.org


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## FLYBOYJ (Jul 20, 2021)

pbehn said:


> In flight test reports here P-39 Performance Tests there is Normal rated power, Military power and War emergency power and the critical altitudes these were at, for level speeds and climb, this sort of stuff isnt my "bag" which is why I was asking where he got his info. I am pleased to see from other posts the laws of physics also apply to the P-39.


In my years in aviation you usually weed out the BS'ers when they get basic terms and definitions wrong. I'm always willing to educate and at the same time learn but all hope is lost when one is shown they are wrong but are not willing to accept their errors. "Legends in their own minds."

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## GregP (Jul 20, 2021)

Thank you Bill Marshall for post 2,854. I'm pretty sure we have beaten the P-39 to death and our P-39 Enthusiast (maybe not quite Expert) still won't see the light of day.

One often-quoted definition of insanity is doing the same thing over and over and expecting a different result. I believe we're have arrived there. We have met the enemy and he is now us. At least most of us know how to use a pilot's operating handbook and the charts therein, so it hasn't been all for naught.

The P-63 was a pretty decent airplane, but also wasn't going to be used for escort work. The P-39 got better with time, but wasn't what was needed and never was a high-altitude airplane, but it wasn't too bad if you stayed under 12,000 feet and kept pretty close to home. Outside of that narrow mission, it was out of its element.

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## wuzak (Jul 20, 2021)

P-39 Expert said:


> Switch to drop tank is a lot earlier, right after gear and flaps up and climb speed has been established. Most of the fuel used on the ground and during takeoff will drain back into the main internal tanks. Most of the 20gal takeoff/climb allowance is used climbing toward the target and is therefore used in the range calculations.



Did the fuel pumps run at constant flow?

If so, wouldn't the take-off/climb allowance be the fuel actually used, not the fuel flowing from the tank? Bearing in mind that take-off is performed at near maximum power and fuel flow rate.


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## Shortround6 (Jul 20, 2021)

The engine in the P-39 used 109 gallons an hour to make 1000hp at 2600 rpm. Or 9.17 hp/hr/ gal

At military power of 1125hp/3000rpm it used 138 gallons an hour or 8.15 hp/hr/ gal. 

You don't get to use the lower fuel consumption of max continuous when figuring military power.

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## XBe02Drvr (Jul 20, 2021)

Peter Gunn said:


> Yeeeaaaaah...
> 
> I still don't think you get the whole "range" and "mission planning" thing let alone the mission profile for deep penetration escort.


Like trying to teach a tortoise to fly.

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## P-39 Expert (Jul 20, 2021)

Shortround6 said:


> The engine in the P-39 used 109 gallons an hour to make 1000hp at 2600 rpm. Or 9.17 hp/hr/ gal
> 
> At military power of 1125hp/3000rpm it used 138 gallons an hour or 8.15 hp/hr/ gal.
> 
> You don't get to use the lower fuel consumption of max continuous when figuring military power.


You need to use the fuel consumption at 25000' or 62gph at normal power (2600rpm). You must estimate military power consumption at that height, it is not quoted anywhere in the manual.

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## GrauGeist (Jul 20, 2021)

I looked at all the charts and simply could not find the figures for "Ludicrous Speed".
Shouldn't it be found by the "Combat Speed" portion of the chart?

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## pbehn (Jul 20, 2021)

I also doubt and air force would routinely switch fuel source as its pilots lifted off and raised undercarriage, eventually there will be a problem with a valve or an air lock and a pilot will die.


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## XBe02Drvr (Jul 20, 2021)

pbehn said:


> In the tests mentioned they quote different design numbers, diameter and even the blade angle range in one case. *There is absolutely no way a test pilot knows what the implication of this is unless he is told by someone who does.*


Actually, a trained test pilot knows a lot more of this stuff than you give him credit for. Many, if not most of them are engineers by training and very few are your stereotypical "Joe Pilot" who just happened to fly a test hop.
A member of our flying club was a Navy Test Pilot School graduate, had a masters in aero engineering from Purdue, combat experience in Korea, had worked in engineering test at Edwards, instructed at the NTPS at Pax River, and would be the first to tell you that the young ones coming up were way better educated than he was.

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## pbehn (Jul 20, 2021)

P-39 Expert said:


> You need to use the fuel consumption at 25000' or 62gph at normal power (2600rpm). You must estimate military power consumption at that height, it is not quoted anywhere in the manual.


I have asked you 3 times where you get this from. WHERE DO YOU GET IT FROM?

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## buffnut453 (Jul 20, 2021)

I wish you chaps would stop groundhogging this thread with all this boring talk about aircraft performance. I'm still waiting for an answer to my post #2746 about the gas heater. Now there's a KEY question that needs answering!!!

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## buffnut453 (Jul 20, 2021)

FLYBOYJ said:


> *LET THE GROUNDHOGGERY BEGIN!*



Dude, the groundhoggery has been going on for over a year. I really, REALLY don't want it to start all over again!

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## buffnut453 (Jul 20, 2021)

Peter Gunn said:


> My God man, have you learned NOTHING in this thread?



If so, he's not the only one!

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## P-39 Expert (Jul 20, 2021)

drgondog said:


> No. Test weights stated are Always GW before takeoff.
> 
> Conditions including taped gun ports, removal of sway braces, external tank/no tank. The Test weights Were mostly conducted Under combat weights - and as such Optimistic'. Major Price was the Wright Field Bell project officer and notorious for producing 'optimistic' reports. I draw your attention to comparisons of RAF test results to Wright and Bell tests.
> 
> ...


Test weights were average weight for that flight, starting with full fuel and landing with a small reserve. British used 95% of published gross weight as the noted weight in their tests. None of the official Wright Field tests were noted at the published gross weight of the plane. None in wwiiaircraftperformance.org anyway.

So the test was bad because of a Major Price? A Wright Field performance test?

Weight of a 75gal drop tank with fuel is only 500lbs (450lbs fuel and 50lbs tank), not 800.

You are on the wrong chart if you are figuring range. Everything you need for range is on the Flight Operation Instruction Chart, nothing on the Takeoff, Climb and Landing Chart will help you with range or radius. Don't use the "Fuel From S.L" figures for range, that's all factored in on the Flight Operation Instruction Chart.

Please, I have never said that a P-39 was a "Super Escort". The question was could it escort bombers in Europe. I have proven that many times by using information from the pilot's manual.

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## pbehn (Jul 20, 2021)

XBe02Drvr said:


> Actually, a trained test pilot knows a lot more of this stuff than you give him credit for. Many, if not most of them are engineers by training and very few are your stereotypical "Joe Pilot" who just happened to fly a test hop.
> A member of our flying club was a Navy Test Pilot School graduate, had a masters in aero engineering from Purdue, combat experience in Korea, had worked in engineering test at Edwards, instructed at the NTPS at Pax River, and would be the first to tell you that the young ones coming up were way better educated than he was.


I have no doubt about that at all, even in WW2 pilots had instruction on how planes worked, but when it comes to the actual prop in front of him, without starting to measure diameter chord and profile then check all the workings of the pitch mechanism he can just note the manufacturer's product number. 

In the test reports I linked one stated the blade angle range and the other didnt, I presume that is because he was asked to, because it had become significant.


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## pbehn (Jul 20, 2021)

buffnut453 said:


> I wish you chaps would stop groundhogging this thread with all this boring talk about aircraft performance. I'm still waiting for an answer to my post #2746 about the gas heater. Now there's a KEY question that needs answering!!!


Have you noticed how we have leapt from proving a Bf 109 couldnt get a bomb to 25,000ft onto proving that a P-39 could haul a 110gallon tank to the same height and cruise effortlessly, economically and with eternal grace?

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## Clayton Magnet (Jul 20, 2021)

Forgive my ignorance, but how could a single stage Allison haul a 110 gallon tank to 25000 feet, when it started gasping for air about 10000 feet lower?

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## GrauGeist (Jul 20, 2021)

P-39 Expert said:


> I have proven that many times by using information from the pilot's manual.


Then why didn't they?

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## XBe02Drvr (Jul 20, 2021)

P-39 Expert said:


> Test weights were average weight for that flight, starting with full fuel and landing with a small reserve. British used 95% of published gross weight as the noted weight in their tests. None of the official Wright Field tests were noted at the published gross weight of the plane. None in wwiiaircraftperformance.org anyway.
> 
> So the test was bad because of a Major Price? A Wright Field performance test?
> 
> ...


UN-EFFING-BELIEVABLE!! A tortoise lecturing an eagle on flight performance! I can die now, content that I've seen everything. Thank god for the 1st amendment. Everybody is entitled to express their opinion, and the entertainment value is priceless!

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## DerAdlerIstGelandet (Jul 20, 2021)

drgondog said:


> No. Test weights stated are Always GW before takeoff.
> 
> Conditions including taped gun ports, removal of sway braces, external tank/no tank. The Test weights Were mostly conducted Under combat weights - and as such Optimistic'. Major Price was the Wright Field Bell project officer and notorious for producing 'optimistic' reports. I draw your attention to comparisons of RAF test results to Wright and Bell tests.
> 
> ...

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## Peter Gunn (Jul 20, 2021)

P-39 Expert said:


> Test weights were average weight for that flight, starting with full fuel and landing with a small reserve. British used 95% of published gross weight as the noted weight in their tests. None of the official Wright Field tests were noted at the published gross weight of the plane. None in wwiiaircraftperformance.org anyway.
> 
> So the test was bad because of a Major Price? A Wright Field performance test?
> 
> ...


Dude, there is no doubt to me you are trolling now, if I had any previous doubts you've removed them with this response to 

 drgondog

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## pbehn (Jul 20, 2021)

P-39 Expert said:


> Please, I have never said that a P-39 was a "Super Escort". The question was could it escort bombers in Europe. I have proven that many times by using information from the pilot's manual.


The Mustang Mk II/ P-51A if fitted with a rear internal tank would have more internal fuel than your P-39 has in total, it could also carry external tanks. It did 410MPH at 10,000ft and was, at the time, one of if not the fastest at that altitude. 1,500 were made 50 went to the British/RCAF, it our performed the P-39 in every way but was not considered for long range escort, why cant you consider you just got it wrong.


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## P-39 Expert (Jul 20, 2021)

Peter Gunn said:


> Dude, there is no doubt to me you are trolling now, if I had any previous doubts you've removed them with this response to
> 
> drgondog


I guess I don't know what trolling means. Can you enlighten me?


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## P-39 Expert (Jul 20, 2021)

pbehn said:


> The Mustang Mk II/ P-51A if fitted with a rear internal tank would have more internal fuel than your P-39 has in total, it could also carry external tanks. It did 410MPH at 10,000ft and was, at the time, one of if not the fastest at that altitude. 1,500 were made 50 went to the British/RCAF, it our performed the P-39 in every way but was not considered for long range escort, why cant you consider you just got it wrong.


Did not outperform the P-39N in climb, ceiling or turning radius. Speed was about 10-15mph difference.


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## XBe02Drvr (Jul 20, 2021)

buffnut453 said:


> I'm still waiting for an answer to my post #2746 about the gas heater. Now there's a KEY question that needs answering!!!


My frozen toes concur!

Had one fail at 12,000 feet over Presque Isle ME headed for Manchester NH with an OAT of -25°F two days before Christmas. Not fun!

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## pbehn (Jul 20, 2021)

P-39 Expert said:


> Did not outperform the P-39N in climb, ceiling or turning radius. Speed was about 10-15mph difference.


You need to remember your P-39 has a 110gal tank on, and when it drops it it still has the shackles, the difference in performance is in the tests I posted but which you havnt read. This was mentioned in Drgondogs post but you didnt read that either.

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## XBe02Drvr (Jul 20, 2021)

P-39 Expert said:


> I guess I don't know what trolling means. Can you enlighten me?


It's when you drag your nether bits through the water to see what will bite.

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## pbehn (Jul 20, 2021)

XBe02Drvr said:


> It's when you drag your nether parts through the water to see what will bite.


Without the protection of an urchin shaped codpiece.

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## buffnut453 (Jul 20, 2021)

P-39 Expert said:


> I guess I don't know what trolling means. Can you enlighten me?



Internet troll - a person who intentionally tries to instigate conflict, hostility, or arguments in an online social community.

Common characteristics include:
- Continuing with a line of argument even after it's been thoroughly debunked.
- Ignoring posts that contradict the argument being made.
- Changing the scope of the argument when contradictory evidence has been provided.
- Making statements without providing evidence to support the assertion.

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## P-39 Expert (Jul 20, 2021)

FLYBOYJ said:


> For the sake of discussion here are the charts. Colors were added by me.
> 
> View attachment 632925
> 
> ...


While you are at it, get your red pen and circle "At 12000 Ft Only" at the top of column 1 of the Flight Operation Instruction Chart (range chart).

We're still figuring range and combat radius, right? On the Specific Engine Flight Chart you have the Fuel Flow column circled in yellow. Those numbers are for 14000'-15500'. What does that have to do with cruise or combat fuel flow at 25000'? Absolutely nothing.

Then on the Takeoff, Climb and Landing Chart you have Time From SL and Fuel Flow From SL circled in red. What does that have to do with range? Absolutely nothing. In the 8000lb row (drop tank) the 25000' column shows 29.9 minutes and 31.2gal from SL. The 31.2gal figure is a misprint when compared with the other figures in that column. Probably meant 42gal or so like the P-39N chart. Anyway, how far is this plane traveling in the 29.9 minutes that it takes to climb to 25000'? Since the plane climbs at about 170mph IAS then the average TAS is about 220mph. In that 29.9 minutes the plane has traveled 110mi. Unless of course the plane is climbing AWAY from the target, or somehow helicoptered up to 25000' without moving toward the target. These figures are worthless when figuring range.

Go to the Flight Operation Instruction Chart. This is the range chart. Go to any column. Divide the gallons available by the U.S GPH (gallons per hour) to get flight time. Multiply that by the IAS then convert that to TAS. As an example use column III at 15000'. 145gal divided by 70gph = 2.07hrs. 2.07 hrs x IAS 206mph = 426mi. Convert to TAS = 554mi. Now go up the column to the Range In Air Miles at 145gal. It says 499mi, not 554mi. The very smart AAF officers who put together this chart have already factored in the total fuel used and the miles gained while climbing to 25000'. They did this so the pilot can simply deduct the 20gal for warmup and climb to 5000' from total fuel and the range values work for any altitude and power setting. The pilot doesn't need to worry about the actual fuel used or the miles gained while climbing. It's already figured in the chart. 

Don't use figures from the Takeoff, Climb and Landing Chart or the Specific Engine Flight Chart. They are not for figuring range. Use the Flight Operation Instruction Chart. Deduct the 20gal Takeoff and Climb allowance from total fuel. The rest is done for you.


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## DerAdlerIstGelandet (Jul 20, 2021)

I love it when armchair pilots with zero hours tell real pilots how to read and compute charts.

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## buffnut453 (Jul 20, 2021)

P-39 Expert said:


> The very smart AAF officers who put together this chart have already factored in the total fuel used and the miles gained while climbing to 25000'. They did this so the pilot can simply deduct the 20gal for warmup and climb to 5000' from total fuel and the range values work for any altitude and power setting. The pilot doesn't need to worry about the actual fuel used or the miles gained while climbing. It's already figured in the chart.



This is absolute bollocks. Every mission...repeat EVERY mission involving long-range escort would factor in weather, particularly winds, to ensure that the required range could achieved. Apply any headwind and your range will be reduced because you have to use more fuel to overcome the additional drag...oh, and winds change during a long mission so it's entirely possible to have headwinds in both directions, or to have tailwinds in both directions. All of that has to be planned into the mission. Pilots didn't just read off a chart, climb into their jalopy and commit aviation. 

As has been pointed out many times (but you keep ignoring it) the range for a single aircraft is not the same as the range for a squadron of aircraft. You can't take off an entire squadron all at once, which means some amount of time will be spent forming up in the air. This was typically done by flying circuits around the home airfield until all the aircraft were in formation, and only then setting course for the target. All that time circling will use up fuel that can't be used on the mission. Then you have aircraft within the formation offering differing performance or being unable to maintain a constant throttle setting due to formation keeping. All of that will burn more fuel per aircraft than the case for a single aircraft.

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## pbehn (Jul 20, 2021)

I think the 600 bomber formation of B-17s formed up behind the P-39 which led them to Berlin, if the mission was planned correctly, of course.

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## FLYBOYJ (Jul 20, 2021)

I posted the charts for the P-39 N and Q and both sets of flight operation instruction chart contain this statement, varying with configuration:







So that chart tells me that there is a 20 gallon allowance for warm up and climb to 5000'.

BUT on the climb data chart we have this:






it also says this on the bottom of the same chart;






If you look at the climb chart and flight operation instruction chart. they are in conflict with each other as the climb to 5000' is more than 20 gallons (depending on weight)







So let me put this out there to my fellow pilots, especially Wes, Bill and Biff (if you wish to partake in this groundhoggery) who are all ATPs and have way more time in the air than this Commercially Rated CFII who only flies SEL aircraft - how would you interpret this?

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## SaparotRob (Jul 20, 2021)

Clayton Magnet said:


> Forgive my ignorance, but how could a single stage Allison haul a 110 gallon tank to 25000 feet, when it started gasping for air about 10000 feet lower?


I don’t think you are getting in the spirit of the thread.

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## FLYBOYJ (Jul 20, 2021)

DerAdlerIstGelandet said:


> I love it when armchair pilots with zero hours tell real pilots how to read and compute charts.


Chris - when you were taking your flight training did your instructor ever tell you to ignore the climb charts and just calculate your cross country based on range? I know you fly Pipers, love those slide chart!


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## Glider (Jul 20, 2021)

P-39 Expert said:


> Did not outperform the P-39N in climb, ceiling or turning radius. Speed was about 10-15mph difference.


You have never answered this question which has been put a number of times.

If the P39N (the one you always quote) was so good, why did they produce thousands of the P39Q?

I mention this :-
a) Because I would like to know
b) Every other combat aircraft I can think of improved with the exception of the P39, why was that?

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## Marcel (Jul 20, 2021)

My conclusion is that there must be some masochistic tendencies amongst the members of this forum. It’s the only way I can explain that this discussion is still raging.

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## pbehn (Jul 20, 2021)

SaparotRob said:


> I don’t think you are getting in the spirit of the thread.


He loses me as soon as he mentions heading straight to a target, they took off, formed up as a group then formed up with others and headed straight to a rendezvous at a certain time an place, then did what they had to do until someone else did it at another RDV. Even PR pilots flying alone didnt head straight to anywhere, they avoided flack and fighter bases and changed course regularly to avoid being intercepted. If you always head straight to where you want to go you give your opponents hours to prepare an attack. Oh and if you head straight to Berlin from most US bases in South East England you fly over all the heavily defended areas of Netherlands the Ruhr and Hanover. Duisburg, Mulheim, Essen, Dortmund, Hanover and Berlin are aligned pointing to England like the stones in Stonehenge.

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## SaparotRob (Jul 20, 2021)

pbehn said:


> He loses me as soon as he mentions heading straight to a target, they took off, formed up as a group then formed up with others and headed straight to a rendezvous at a certain time an place, then did what they had to do until someone else did it at another RDV. Even PR pilots flying alone didnt head straight to anywhere, they avoided flack and fighter bases and changed course regularly to avoid being intercepted. If you always head straight to where you want to go you give your opponents hours to prepare an attack. Oh and if you head straight to Berlin from most US bases in South East England you fly over all the heavily defended areas of Netherlands the Ruhr and Hanover. Duisburg, Mulheim, Essen, Dortmund, Hanover and Berlin are aligned pointing to England like the stones in Stonehenge.


The P-39 just flies higher than the flak. D’uh.

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## XBe02Drvr (Jul 20, 2021)

FLYBOYJ said:


> So let me put this out there to my fellow pilots, especially Wes, Bill and Biff (if you wish to partake in this groundhoggery) who are all ATPs and have way more time in the air than this Commercially Rated CFII who only flies SEL aircraft - how would you interpret this?


I haven't got time to dig into the charts right now, but rule of thumb if you don't want your pilots to take an unscheduled swim: ALWAYS take the LEAST optimistic figure, then start deducting for contrary circumstances from there. Tail End Charlie will be flying the most beat up least efficient plane in the squadron, will burn the most fuel throttle jockeying at the whiplash end of the formation, and be the one whose loss you'll have to explain to the CO and whose parents you'll have to write THE LETTER to after everybody else returns safe.

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## Dash119 (Jul 20, 2021)

SaparotRob said:


> The P-39 just flies higher than the flak. D’uh.


Just one of the many reasons to remove the nose armor...

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## pbehn (Jul 20, 2021)

SaparotRob said:


> The P-39 just flies higher than the flak. D’uh.


Another thing they didnt think of, just fly at 25,000ft and nothing can get you.


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## P-39 Expert (Jul 20, 2021)

FLYBOYJ said:


> I posted the charts for the P-39 N and Q and both sets of flight operation instruction chart contain this statement, varying with configuration:
> 
> View attachment 632942
> 
> ...


If there is a 20gal allowance for takeoff and climb to 5000', then why are other altitudes listed on the chart? And why aren't there specific allowances for every altitude? Because the 20gal allowance works for all the altitudes and power settings for the chart. Fuel used during climb and the cruising range during that climb are already factored in. To make it easier for the pilot to use the chart.

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## XBe02Drvr (Jul 20, 2021)

P-39 Expert said:


> Because the 20gal allowance works for all the altitudes and power settings for the chart. Fuel used during climb and the cruising range during that climb are already factored in. To make it easier for the pilot to use the chart.


No way, Jose! There are no "one size fits all"s in aircraft performance. Any competent pilot, when presented with one, had better adopt a "show me" attitude and verify its accuracy if surviving to old age is important to them. Your armchair won't dump you in the drink; your P39 will.

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## XBe02Drvr (Jul 20, 2021)

Marcel said:


> My conclusion is that there must be some masochistic tendencies amongst the members of this forum. It’s the only way I can explain that this discussion is still raging.


It's a manifestation of our sense of brotherhood and charity that we will put in all this effort to help our wayward member see the light, despite his mental attributes apparently resembling those of a creature whose contribution to the breakfast table we worship here, and whose feral cousin totes a 30MM firehose and hunts diesel armadillos for a living. Don't you find that honorable?

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## 33k in the air (Jul 20, 2021)

P-39 Expert said:


> If there is a 20gal allowance for takeoff and climb to 5000', then why are other altitudes listed on the chart? And why aren't there specific allowances for every altitude?



There are. It's right there on the *Take-Off, Climb, and Landing* charts page. An image of it has been provided in this post.

At 8,000 lbs take-off weight:

24.5 gallons used to 5,000 feet
29.2 gallons used to 10,000 feet
35.3 gallons used to 15,000 feet
39.7 gallons used to 25,000 feet

The higher you go the more fuel is going to be used because more energy must be expended to get higher up. Basic physics.

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## FLYBOYJ (Jul 20, 2021)

P-39 Expert said:


> If there is a 20gal allowance for takeoff and climb to 5000', then why are other altitudes listed on the chart? And why aren't there specific allowances for every altitude? Because the 20gal allowance works for all the altitudes and power settings for the chart. Fuel used during climb and the cruising range during that climb are already factored in. To make it easier for the pilot to use the chart.


There's also a relief tube to make it easier on the pilot.

Wes said it - *it isn't "one size fits all."* You are so wrong in so many fronts and now you're going to try to dispute this was an ATP. Incredible! This is why I stopped addressing this many posts back. You don't know how to use the charts, that simple, the same way you didn't know how to do weight and balance so you can continue with your narcissist belief that you know what you're doing, there are some of us who have actually used similar charts for actual flights. So tell us, how many cross country flight hours have you flown calculating flight data?

BTW - I will say that there are errors on those charts and missing data so I will give you that. Aside from that all is good if you plan to take off and fly at 5000' all day!


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## pbehn (Jul 20, 2021)

XBe02Drvr said:


> No way, Jose! There are no "one size fits all"s in aircraft performance. Any competent pilot, when presented with one, had better adopt a "show me" attitude and verify its accuracy if surviving to old age is important to them. Your armchair won't dump you in the drink; your P39 will.


From the little I have read compared to others who post, the mission planners had the power to inflict more losses on their own than the opposition. Imagine the bombers not being escorted because of a screw up in timing, not being able to land because of weather and the escorts ditching, running out of fuel trying to find them.

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## XBe02Drvr (Jul 20, 2021)

pbehn said:


> Imagine the bombers not being escorted because of a screw up in timing, not being able to land because of weather and the escorts ditching, running out of fuel trying to find them.


You don't have to imagine that scenario. It happened. More than once.

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## pbehn (Jul 20, 2021)

XBe02Drvr said:


> You don't have to imagine that scenario. It happened. More than once.


I know I mean not losing a few but half of the mission.


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## pbehn (Jul 20, 2021)

Glider said:


> You have never answered this question which has been put a number of times.
> 
> If the P39N (the one you always quote) was so good, why did they produce thousands of the P39Q?
> b) Every other combat aircraft I can think of improved with the exception of the P39, why was that?


As a military plane the P-39 improved the way that a Typhoon improved, according to what the client wanted, it was reinforced and had armour added to make it more useful, not faster or better climbing. The Q had a lot of mods that the Russians asked for, who seemed to have similar ideas to the British.


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## buffnut453 (Jul 20, 2021)

Aaanndd...another 2 pages have been filled and I'm still waiting a response to my post #2746.

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## FLYBOYJ (Jul 20, 2021)

buffnut453 said:


> Aaanndd...another 2 pages have been filled and I'm still waiting a response to my post #2746.


It's like waiting at the DMV to get your driver's license!

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## buffnut453 (Jul 20, 2021)

FLYBOYJ said:


> It's like waiting at the DMV to get your driver's license!


 
Or waiting for USPS to deliver paperwork to the DMV that I posted on 9 July and which was only delivered today...and the distance from where I posted it to where it was delivered is about a 2-hour drive! Sorry...DMV is a sore topic today!!!

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## Shortround6 (Jul 20, 2021)

FLYBOYJ said:


> Hmmm - "*combat power* vs normal power"
> 
> Word search no such thing...
> 
> "Military Power/ Takeoff Power" found in manual.


I would take a pass on this one. You may not find "combat power" In US manuals. 
You might find it in British manuals?
Unfortunately some rather well known authors have used it, rightly or wrongly, Like Francis Dean in AHT. 
For instance he used in the acceleration tables I referenced above. This does tend to scramble things. 
AS long as every body KNOWS that "combat Power" refers to WEP or WER or some other power level _above _"military power" I personally don't have a problem with it. 
Unfortunately some people don't know the difference. 
In the case of the P-39 the difference is mute as the plane can't make anything higher than military power above about 15,500ft.

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## pbehn (Jul 20, 2021)

I just had a thought (dont be alarmed). The P-39 was used a lot as a trainer, are some of these documents applicable to pilot training not operations?

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## fubar57 (Jul 20, 2021)

FLYBOYJ said:


> It's like waiting at the DMV to get your driver's license!


I've always heard that about attaining American drivers licenses and renewals. Where I am now and back in my home town of 20K+, I was in and out in less than 20 minutes tops


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## buffnut453 (Jul 20, 2021)

Shortround6 said:


> I would take a pass on this one. You may not find "combat power" In US manuals.
> You might find it in British manuals?
> Unfortunately some rather well known authors have used it, rightly or wrongly, Like Francis Dean in AHT.
> For instance he used in the acceleration tables I referenced above. This does tend to scramble things.
> ...



AAARRGGGHHHH....one of my pet peeves of the English language: mute = silent, speechless; moot = debatable, doubtful. Methinks you mean the latter.

I'm clearly too grumpy to continue posting to this thread. I'm off to bed.

P.S. Apols SR6...just couldn't resist!

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## GrauGeist (Jul 20, 2021)

fubar57 said:


> I've always heard that about attaining American drivers licenses and renewals. Where I am now and back in my home town of 20K+, I was in and out in less than 20 minutes tops


Each state has it's own Department of Motor Vehicles, but oddly enough, the people that staff them all seem to have the same disposition regardless of geographical location.
In all the years of dealing with civil servants, I have rarely had a pleasant (or timely) experience.


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## FLYBOYJ (Jul 20, 2021)

Shortround6 said:


> I would take a pass on this one. You may not find "combat power" In US manuals.
> You might find it in British manuals?
> Unfortunately some rather well known authors have used it, rightly or wrongly, Like Francis Dean in AHT.
> For instance he used in the acceleration tables I referenced above. This does tend to scramble things.
> ...


I actually looked in a British glossary and couldn’t find it there either.

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## Milosh (Jul 20, 2021)

fubar57 said:


> I've always heard that about attaining American drivers licenses and renewals. Where I am now and back in my home town of 20K+, I was in and out in less than 20 minutes tops


Can't use the mail or on-line? Only time I go is if a photo has to be taken.


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## FLYBOYJ (Jul 20, 2021)

pbehn said:


> I just had a thought (dont be alarmed). The P-39 was used a lot as a trainer, are some of these documents applicable to pilot training not operations?


I’ve seen some separate training manuals written for combat aircraft, never saw one for the P-39


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## pbehn (Jul 20, 2021)

FLYBOYJ said:


> I’ve seen some separate training manuals written for combat aircraft, never saw one for the P-39


In a training aircraft you may well want the pilot to think for himself for his flight, what he learns doing that is then put into the demands of a mission in service as Bill has described a few times. they are related but different skills

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## special ed (Jul 20, 2021)

Having experienced the normal several hour in person DMV in Louisiana, and particular the New Orleans area, I expected similar in Bay St. Louis, Mississippi. I had bought an old pickup to keep on my in laws' property and went to the local office to register and license it. I arrived at opening time expecting a long wait but found the office empty. Suspecting they had left the door unlocked by accident, I was about to turn when I heard a chorus of young women say, "Over here sir." They had been sitting down behind the counter, so I walked to the nearest one, presented my paperwork, was told to sign a computer generated form, was handed a license plate, a temp title and was told I would receive the actual title in two weeks. I walked to the door in amazement looking at what I had and hesitated a moment when the lady called out, "Is something wrong, sir?" I explained I was used to dealing with Louisiana DMV and was surprised by their efficiency.

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## drgondog (Jul 20, 2021)

Expert - please use the 34 gal per the Op Manual to get to 15K but use no less than 20 gal from your internal tank. Construct a mission scenario from say London to Hamburg ~ 280 miles. Pick R/V near Bremen at 25,000 feet with B-17s moving 150IAS/215 TAS... about 15 minutes short of Hamburg.

You have a group of 48 P-39Q's with whatever load out you choose - but deduct 40mph TAS for 75 gal steel unpressurized tank - and stop using belly tank at 17-18K because you have unpressurized fuel system for those tanks. IIRC P-39 Never had the Mod but P-47C didn't start using the 205 al bathtub Ferry tank until end of July 1943. 

Set the boundary conditions as all internal fuel until sometime after take off and formation assembly and initial climb at Take Off and Climb. !2 minutes at MP for Takeoff and MC for orbit to form up at 5K (approx 27 gal internal fuel)

Note from Allison data in Ops Manual that *Military Power up to 14,000 is 138gph* and Max Continuous is 109gph and Max cruise is 74 up to 14,000. You will climb at Max Continuous Power from Formation assembly over London to Point A (18000 feet) on a straight line. How much external tank fuel will you be able to use before dropping at Point A? Where is Point A.

Tell us when you decide to climb to cruise altitude of 25 K and how far you will go in he climb before you have to switch to internal fuel.

From that point (distance and time to reach 18000 feet) you may use only internal fuel to cruise from 18K to 25 K to RV, cruise to target, essing over the B-17s (if you can, turns are hell with only 750 hp available at 25K). 

This will be your key leg. Point A from switch to internal from 75 gal tank at 18K, climb to Point B @25K. Cruise at Max Cruise (2280RPM/31.7 MP - max) to Point C (RV) Ess over B-17s from Point C to Target at D (Maximum Combat Radius). Burn 46 gallons more internal fuel at 20 minutes Military Power over Point D.

Assume 20minutes reserve mandatory for weather, etc. 

Questions - How far will you go from base to Point A. Where is that on a straight line to Bremen. How far to climb and cruise on internal fuel to Bremen after you drop tank. (best case for you). What is time for essing to cover Bremen to Hamburg (at 62 gph). How much fuel remains?

Recall that 27K for swith over to 75 gal external. - Remain over base during form up. Climb straight line to Point A on External. 

Committed internal fuel with zero cruise fuel available =27 TO/Form, 46 for combat, 20 for reserve -----------> more than 87 gallons. How far can you cruise from A to Hamburg and Hamburg to London? on 120 gallon internal tank.?

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## FLYBOYJ (Jul 20, 2021)

Bill, you rock! 😎

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## Thumpalumpacus (Jul 20, 2021)

FLYBOYJ said:


> Bill, you rock! 😎



Why are you calling him a "rock"? He seems like a smart SoB to me.

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## 33k in the air (Jul 20, 2021)

GrauGeist said:


> Each state has it's own Department of Motor Vehicles, but oddly enough, the people that staff them all seem to have the same disposition regardless of geographical location.
> In all the years of dealing with civil servants, I have rarely had a pleasant (or timely) experience.



So, uncivil servants?

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## GrauGeist (Jul 20, 2021)

33k in the air said:


> So, uncivil servants?


Pretty much...

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## SaparotRob (Jul 20, 2021)

There was a television comedy in which Satan comes to Earth to meet his mortal son (deal gone bad). The son has been compelled to bring escaped souls to the portal of Hell. The portal to Hell is at the DMV. 
This is pretty much how we view the DMV here in the U.S.

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## Thumpalumpacus (Jul 20, 2021)

SaparotRob said:


> There was a television comedy in which Satan comes to Earth to meet his mortal son (deal gone bad). The son has been compelled to bring escaped souls to the portal of Hell. The portal to Hell is at the DMV.
> This is pretty much how we view the DMV here in the U.S.

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## pbehn (Jul 20, 2021)

FLYBOYJ said:


> Bill, you rock! 😎


I dont see what is so difficult to understand but I used to drive between all these places and it is exactly the same for a car if you substitute altitude for passengers. Try booling along at 100mph with three passengers and 4 suitcases with a two litre car, you use almost exactly three times the fuel that you use driving alone at 80-90MPH but with petrol stops and screw ups on the motorway, it takes the same amount of time.

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## Thumpalumpacus (Jul 20, 2021)

pbehn said:


> I dont see what is so difficult to understand but I used to drive between all these places and it is exactly the same for a car if you substitute altitude for passengers. Try booling along at 100mph with three passengers and 4 suitcases with a two litre car, you use almost exactly three times the fuel that you use driving alone at 80-90MPH but with petrol stops and screw ups on the motorway, it takes the same amount of time.



Or where I live, in the aptly-named Hill Country of Texas, with regular climbs and valleys of up to 600 foot or so, at up to 20% gradients. If you want to maintain speed in the climb, you downshift, increasing revs and manifold pressure, which fuel loss you don't regain on the backside of the hill because you must 1) still be in gear (meaning you're then [finally!] at efficient cruise, for a few moments), and 2) still make adjustments for traffic flow and safe spacing between vehicles, which requires fuel as well as braking.

I have no doubt your experience driving in the mountains, not hills, of Europe, underlines this point even further.


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## SaparotRob (Jul 20, 2021)

RE post # 2926:
The more knowledgeable among us may find this thread infuriating. I think it’s perhaps the most informative source I’ve read about the actual nuts and bolts of flying. My real favorite airplane is the B-17. What drgondog just posted is the part of air war that didn't make it to the movies. 
There have been explanations for:
how planes perform (other than the P-39)
flight planning
aerodynamics
armaments

AND the best running joke ever!
Great thread.

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## pbehn (Jul 20, 2021)

Thumpalumpacus said:


> Or where I live, in the aptly-named Hill Country of Texas, with regular climbs and valleys of up to 600 foot or so, at up to 20% gradients. If you want to maintain speed in the climb, you downshift, increasing revs and manifold pressure, which fuel loss you don't regain on the backside of the hill because you must still 1) be in gear (meaning you're then [finally!] at efficient cruise, for a few moments), and 2) still make adjustments for traffic flow and safe spacing between vehicles, which requires fuel as well as braking.
> 
> I have no doubt your experience driving in the mountains, not hills, of Europe, underlines this point even further.


Well there are no mountains in that area it is almost completely flat, but from the German Border you climb up and before Hanover you descend (on average even on an autobahn it is up and down). On a car with instantaneous and average consumption on the "computer" it was 4 MPG more east to west than west to east. Driving in and around the Alps is a whole new ball game, especially if a tunnel gets shut.

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## Thumpalumpacus (Jul 20, 2021)

pbehn said:


> Well there are no mountains in that area it is almost completely flat, but from the German Border you climb up and before Hanover you descend (on average even on an autobahn it is up and down). On a car with instantaneous and average consumption on the "computer" it was 4 MPG more east to west than west to east. Driving in and around the Alps is a whole new ball game, especially if a tunnel gets shut.



Wait just a gosh-darn minute! Are you saying driving conditions affect mileage?

Why yes, yes, you are!

How much moreso it must be for a vehicle that doesn't have the ground in place supporting it ...

I've driven through some good mountain ranges, and my experience is that the more elevation and directional changes I drive through, the more fuel my crate uses. Engines like simplicity, which is a word no combat-pilot would use to describe forming up and setting out on a 500-mile round-trip.

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## wuzak (Jul 20, 2021)

drgondog said:


> Committed internal fuel with zero cruise fuel available =27 TO/Form, 46 for combat, 20 for reserve -----------> more than 87 gallons. How far can you cruise from A to Hamburg and Hamburg to London? on 120 gallon internal tank.?



Assuming, of course, that your P-39 is fitted with the 120 gallons worth of fuel tanks.

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## FLYBOYJ (Jul 20, 2021)

Loving this guys! I mention the DMV and we add on 2 more pages! LOL!

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## wuzak (Jul 20, 2021)

P-39 Expert said:


> Test weights were average weight for that flight, starting with full fuel and landing with a small reserve. British used 95% of published gross weight as the noted weight in their tests. None of the official Wright Field tests were noted at the published gross weight of the plane. None in wwiiaircraftperformance.org anyway.



I believe the British corrected performance to 95% of gross weight. Not tested at 95% gross weight, since the weight varied during a test flight.

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## wuzak (Jul 20, 2021)

FLYBOYJ said:


> Loving this guys! I mention the DMV and we add on 2 more pages! LOL!



I went away for less than half a day and 4 pages were added.

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## Thumpalumpacus (Jul 20, 2021)

SaparotRob said:


> RE post # 2926:
> The more knowledgeable among us may find this thread infuriating. I think it’s perhaps the most informative source I’ve read about the actual nuts and bolts of flying. My real favorite airplane is the B-17. What drgondog just posted is the part of air war that did’nt make it to the movies.
> There have been explanations for:
> how planes perform (other than the P-39)
> ...



Most probably haven't noticed, but I think most of the likey-type things I've offered here have been the "informative" check-marks, because I'm learning so much about the capabilities not only of specific airplanes, but of the thinking in general that lays behind planning a flight, or -- gasp! -- a mission.


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## Shortround6 (Jul 20, 2021)

P-39 Expert said:


> You need to use the fuel consumption at 25000' or 62gph at normal power (2600rpm). You must estimate military power consumption at that height, it is not quoted anywhere in the manual.



No, you can't do it that way.

It doesn't take into account the different internal friction and supercharger drive requirements.

Please look at the manual again. 


Power level.............................HP .......................rpm.......................altitude....................fuel per hour.......................HP/hr/gal
MIlitary...................................1125......................3000.......................15,500.......................138...........................................8.15
Max continuous.................1000........................2600.......................14,000.......................109..........................................9.19
Economical max..................750.......................2280.......................14,000..........................74..........................................10.13
Minimum cruising (R).......600.......................2190........................14,000..........................52.........................................11.53
Minimum cruising (L).......600.......................2190........................14,000..........................48..........................................12.5



P-39 Expert said:


> Regarding my estimate for fuel burn at combat power vs normal power, you are correct that going from 2600rpm to 3000rpm is about a 15% increase. That's the increase in fuel burn that I used for my estimate. Throttle setting was the same (full), mixture setting was the same (auto rich), plane was well above critical altitude. Only difference was rpm.


Please note that in above examples from the manual that in all but the Minimum cruise (L) the mixture was set to rich. All but the Military rating were at the same altitude. 

Now when the engine goes from 600hp at 2190rpm to 1000hp at 2600rpm we have a 19% increase in rpm, a 60 % increase in power to the prop and a 209%increase in fuel per hour burned or about a 25% increase in fuel burned per HP hour. 



P-39 Expert said:


> You are entitled to your estimate, but that doesn't make it correct



I will throw it back at you.

Explain where the energy needed to over come the changes in internal friction and energy needed to drive the supercharger at the higher speeds come from, please. 
Until you can then you are the one who is incorrect.

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## FLYBOYJ (Jul 20, 2021)

I'm actually enjoying looking into performance data charts, brings back a lot of memories.

When I was working on my PPL I had an epic cross country experience. Darted thunderstorms, barely cleared the Tejon pass in SoCal, bucked 30 MPH headwinds, all in a C152 that survived a mid air, didn't fly straight because the eccentric wing bolts were installed wrong, and wanted to spin when stalled. Flew about 400 airmiles but the 3rd leg of the 300 mile requirement fell short at 298 miles. Because I was learning at a military 141 school (EDW Aero Club) one of my instructors reached out to a DPE and the FAA and I was given a "pass" on my cross country. The rest is History.

Fast forward several years later, I'm in Colorado working on my Commercial. Training at a 141 school and using the VA to finance my flight training, the chief instructor wanted me to re-do my cross country so "their records are clean". Rather then fight this, I decided to go along with it (at the recommendation of my father in law who was my instructor)

The quickest plane I was able to rent for this was a 180 HP C172 with a constant speed prop, all STC installed. It was a good flying bird and I felt comfortable flying it as I took it up several times locally. My plan was to do a short leg by my home airport and then go out 300+ miles into Kansas. Got the POH supplement, did all my calculations, good to go! More to come on that!!!!

All went well after take off but the plane was flying faster and using more fuel than what I calculated. After landing at Hays KS (it was a Sunday) it seemed like the whole town shut down including the airport FBO! After some quick flight planning, I pressed on to my alternate, Norton KS which was 90 miles to the north. I calculated that I would have about an hour of *RESERVE* fuel left. A bit frazzled about the situation, I took off out of Hays and while paying more attention to my charts rather to where I was going, I almost hit the town's church steeple right when services were letting out! I'm sure I got on someone's prayer list that day! 

Arrived at Norton, no issues, but it looked like the FBO there was closed too! Right when I was starting to plan to sleep in the plane that night a pick up truck drove up and the airport manager saved me. I still noticed faster speeds and higher fuel burn.

Got on my way back to KBJC and continued to arrive at my check points 10 to 15 minutes early, WTF!!! Still not to worry, I had plenty of fuel to make it back home and I did.

What I discovered later was the flight manual supplement (for the 180 HP STC) was forged, someone took the amended performance pages and replaced them with copies of the stock pages so all my calculations were about 20% off. People been flying the plane like this for who knew how long! Least to say there was some ass chewing by the people who ran the FBO, the owner pleaded to me not to tell FSDO about this!

Love performance charts!!!!

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## DerAdlerIstGelandet (Jul 20, 2021)

FLYBOYJ said:


> Chris - when you were taking your flight training did your instructor ever tell you to ignore the climb charts and just calculate your cross country based on range? I know you fly Pipers, love those slide chart!



Charts? What are those? I don’t calculate anything. I just hop in and go. I’m an expert.

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## FLYBOYJ (Jul 20, 2021)

DerAdlerIstGelandet said:


> Charts? What are those? I don’t calculate anything. I just hop in and go. I’m an expert.

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## DerAdlerIstGelandet (Jul 20, 2021)

Besides, my instructor did not teach me anything. I taught him by golly.

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## GrauGeist (Jul 20, 2021)

SaparotRob said:


> RE post # 2926:
> The more knowledgeable among us may find this thread infuriating. I think it’s perhaps the most informative source I’ve read about the actual nuts and bolts of flying. My real favorite airplane is the B-17. What drgondog just posted is the part of air war that did’nt make it to the movies.
> There have been explanations for:
> how planes perform (other than the P-39)
> ...


The other factor that has to be taken into account, is that with large bomber formations, there is turbulence created by the lead bombers, so the ones further back are getting buffeted, causing constant flight attitude correction.

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## GregP (Jul 20, 2021)

Hey pben.

He gets it from the P-39Q manual, page 25, chart for 8100 to 7200 pounds ,with 75 gal external tank. First set of columns, there is an entry for 25,000 feet. It says 2600 rpm, 267 mph T.A.S., Full Throttle, 62 U.S. gallons per hour (max continuous power). The climb data from the same manual says it will climb at 750 fpm at 135 mph in a combat climb and 650 fpm at 140 mph in a ferry climb at 25,000 feet. Combat missions were at 3000 rpm and 44..5 " MAP. Ferry mission were at 2300 rpm, 31" MAP (page 23).

When he gets to 25,000 feet, the pilot has to reduce to max continuous (2600 rpm, F.T.), level off, and accelerate to 267 mph. He'd better be quick about it because the range is not much, so he has to turn around rather quickly.

Range is unknown because the range tables are at S.L. and 12,000 feet. Ain't much performance at 25,000 feet. An old Spitfire from 1941 could climb at 3 times the rate, was faster, and had better range.

Let's look at it for the P-39Q. Assume for the sake of argument we are on the drop tank from engine startup, to save arguments and get the best possible result.

87 gallons internal, 75 gallons aux tank. Total = 162 gals.

Climb to 25,000 feet at combat settings takes 13.1 minutes and eats up 39 gallons, leaving 123 gallons, per the manual. Assume we average about 140 mph (goes from 160 mph to 135 mph along the climb for best rate). That moves us forward about 29.5 mile. Let's call it 30 miles.

Assume we cruise at 25,000 feet at max continuous (2600 rpm, F.T., 62 gph burn). We have 36 gallons of aux tank fuel left. That's enough to go for a while 34.8 minutes at 267 mph T.A.S., if we instantly accelerate from the 135 mph climb speed to cruise speed. 34.8 minutes at 267 mph gets us 155 miles farther from home. We are now 155 + 30 = 185 miles from home and we drop the aux tank because it is EMPTY.

Sine we now have no external stores, we use the no external stores chart. Here's where it REALLY gets interesting. We don't change power because we are at full throttle, but our 267 mph T.A.S. with the external tank now magically jumps to 330 mph I.A.S. (if you believe the P-39Q manual). On a standard day, 330 mph I.A.S. becomes 498 mph! So dropping the 75-gallon tank somehow magically makes us accelerate from 267 mph T.A.S. to 498 mph T.A.S. , according to the P-39Q manual.

I think some marijuana was somehow involved in writing this manual. I'll make the assumption that they MEANT to say T.A.S. in both places. So, we now accelerate from 267 mph to 330 mph. Again, pretty doubtful, to me. But, let's run with it.

OK, we now run into our 10 minutes of combat at 25,000 feet and 62 gph and somehow, we manage to engage in this combat at 25,000 feet without losing any height and without getting any close or farther from home. Doubtful, but what the heck, let's ty it. The 10 minutes will eat up 10.33 gallons, leaving us 76.67 gallons of fuel, still at 25,000 feet and 330 mph T.A.S., which takes us 408 miles before we are a glider pilot.

But, suppose I want my half hour of reserve so I'm NOT a glider pilot. That means we only can use 45.6 gallons of the 76.67 gallons we have remaining, still at 25,000 feet and 62 gph, still at full throttle. That means we can only go 243 miles instead of 408 miles.

So, we went 185 miles, had combat for 10 minutes, and we now have 243 miles of range left. Our total distance we can travel will be 185 + 243 = 428 miles, so our combat radius range is now 214 miles and we end up over home base at 25,000 feet with 31 gallons of fuel remaining. Great.

We went from less than 190 miles range from my earlier post all the way to 214 miles range. We gained 24 miles * 2, or 48 miles. Nice.

But, to do that, we needed to be on aux fuel from takeoff (likely against procedures), needed instant acceleration from climb to cruise and instant acceleration from cruise with tank to cruise without tank, needed an instant turnaround at 214 miles, and we needed to have combat joined sometime AFTER we used up the entire aux tank, and also needed the combat to stay at 25,000 feet and get no closer or farther from home.

Offhand, I'd say we needed an absolutely ideal P-39Q mission to get a whole 214 miles from home. Definitely a niche airplane. And my earlier post with 170 - 185 miles of radius would be about right. And I don't think a P-39Q will cruise at 330 mph at 25,000 feet unless there really IS a flying pig somewhere in regular passenger service. At least you don't have to clear the plugs because you're already at full power.

This is futile, but was a bit fun, considering the 498 mph T.A.S. thing. A 498 mph P-39Q? Naahhhhhhhhh ....

Cheers.

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## SaparotRob (Jul 20, 2021)

GrauGeist said:


> The other factor that has to be taken into account, is that with large bomber formations, there is turbulence created by the lead bombers, so the ones further back are getting buffeted, causing constant flight attitude correction.


A topic brought up earlier this thread. I just mentally scaled up the fleets of fighters to fleets of bombers. Great thread.

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## FLYBOYJ (Jul 20, 2021)

GregP said:


> Hey pben.
> 
> He gets it from the P-39Q manual, page 25, chart for 8100 to 7200 pounds ,with 75 gal external tank. First set of columns, there is an entry for 25,000 feet. It says 2600 rpm, 267 mph T.A.S., Full Throttle, 62 U.S. gallons per hour (max continuous power). The climb data from the same manual says it will climb at 750 fpm at 135 mph in a combat climb and 650 fpm at 140 mph in a ferry climb at 25,000 feet. Combat missions were at 3000 rpm and 44..5 " MAP. Ferry mission were at 2300 rpm, 31" MAP (page 23).
> 
> ...



Great post Greg!!!! It's funny, I came up with somewhat similar on a post about 70 pages ago!

I came up with a 140/ 150 mile range with out the drop tank. Amazing!

Great minds think alike! 

Yep - Hempage was rampant during the development of this manual. I think a P-39 might make 498 MPH true while spinning to earth! 






Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)


I felt like doing some math... So this is what I come up with, using those 2 charts posted and I used very conservative numbers except for take off weight, I used the fully loaded 8000 pounds, no wind condition to assume IAS will equal ground speed (for simplicity). Start with 120 gallons (per...



ww2aircraft.net

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## wuzak (Jul 20, 2021)

FLYBOYJ said:


> Yep - Hempage was rampant during the development of this manual. I think a P-39 might make 498 MPH true while spinning to earth!



I was going to say that there were P-39s that could do 498mph TAS. They were known as Augers.

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## SaparotRob (Jul 20, 2021)

GregP said:


> Hey pben.
> 
> He gets it from the P-39Q manual, page 25, chart for 8100 to 7200 pounds ,with 75 gal external tank. First set of columns, there is an entry for 25,000 feet. It says 2600 rpm, 267 mph T.A.S., Full Throttle, 62 U.S. gallons per hour (max continuous power). The climb data from the same manual says it will climb at 750 fpm at 135 mph in a combat climb and 650 fpm at 140 mph in a ferry climb at 25,000 feet. Combat missions were at 3000 rpm and 44..5 " MAP. Ferry mission were at 2300 rpm, 31" MAP (page 23).
> 
> ...


I do believe I understand it now. This post wasn't a bunch guys spitting numbers back and forth. Thanks GregP for explaining one side of the argument so I that I could understand the whole picture. 
I haven't paid attention to the less dramatic aspects of aviation. I gave up on the jet fighter pilot fantasy when I got my first pair of glasses 60 years ago. That was after my dream of being a Coast Watcher. Studying flight plan prep was at the same level of reading tax codes. No reason to bother with it. 
I started following this thread skipping past the numbers. The repartee is gold. That's how I got dragged into The Great Varmint's Burrow of Futility. I couldn't read the official reports posted. What was reprinted was too difficult for my eyes to focus on. So I started paying attention. I started learning (GASP). 
Marcel, I am happy these guys keep coming back here. 
FTL is right around the corner.

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## pbehn (Jul 20, 2021)

GregP said:


> Hey pben.
> 
> He gets it from the P-39Q manual, page 25, chart for 8100 to 7200 pounds ,with 75 gal external tank. First set of columns, there is an entry for 25,000 feet. It says 2600 rpm, 267 mph T.A.S., Full Throttle, 62 U.S. gallons per hour (max continuous power). The climb data from the same manual says it will climb at 750 fpm at 135 mph in a combat climb and 650 fpm at 140 mph in a ferry climb at 25,000 feet. Combat missions were at 3000 rpm and 44..5 " MAP. Ferry mission were at 2300 rpm, 31" MAP (page 23).
> 
> ...


It seems almost all of the discussion is around miss prints and falsified tests. I couldnt understand how getting to 25,000ft was like getting into orbit for one particular aircraft, once there you can cruise at close to maximum speed using just a fraction of the fuel consumption used for climb or flat out runs.

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## buffnut453 (Jul 21, 2021)

FLYBOYJ said:


> Loving this guys! I mention the DMV and we add on 2 more pages! LOL!



And I still don't have an answer to my post #2746...and another page has been added since.

Mebbe I'll get an answer one day....but definitely not holding my breath.


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## FLYBOYJ (Jul 21, 2021)

buffnut453 said:


> And I still don't have an answer to my post #2746...and another page has been added since.
> 
> Mebbe I'll get an answer one day....but definitely not holding my breath.


I think there's a few of you in the same boat here! LOL!


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## buffnut453 (Jul 21, 2021)

SaparotRob said:


> I do believe I understand it now. This post wasn't a bunch guys spitting numbers back and forth. Thanks GregP for explaining one side of the argument so I that I could understand the whole picture.
> I haven't paid attention to the less dramatic aspects of aviation. I gave up on the jet fighter pilot fantasy when I got my first pair of glasses 60 years ago. That was after my dream of being a Coast Watcher. Studying flight plan prep was at the same level of reading tax codes. No reason to bother with it.
> I started following this thread skipping past the numbers. The repartee is gold. That's how I got dragged into The Great Varmint's Burrow of Futility. I couldn't read the official reports posted. What was reprinted was too difficult for my eyes to focus on. So I started paying attention. I started learning (GASP).
> Marcel, I am happy these guys keep coming back here.
> FTL is right around the corner.



See? We suck you in with platitudes and then get you addicted on actual information. Come to the dark side...we have cookies!!! 

At least that's how it's SUPPOSED to work but some people seem immune!

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## GrauGeist (Jul 21, 2021)

buffnut453 said:


> And I still don't have an answer to my post #2746...and another page has been added since.
> 
> Mebbe I'll get an answer one day....but definitely not holding my breath.


I've asked some honest questions during this protracted "conversation" that have gone unanswered, too.

It's aparent that the "authority" of Bell Products chooses to avoid engaging in a direct discussion that runs contrary to his beliefs for fear of having to acknowledge the short-comings of his diety.

So in short, yeah, don't hold your breath for a honest/truthful reply from the guy who would be the world's greatest used car salesman...


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## buffnut453 (Jul 21, 2021)

GrauGeist said:


> I've asked some honest questions during this protracted "conversation" that have gone unanswered, too.
> 
> It's aparent that the "authority" of Bell Products chooses to avoid engaging in a direct discussion that runs contrary to his beliefs for fear of having to acknowledge the short-comings of his diety.
> 
> So in short, yeah, don't hold your breath for a honest/truthful reply from the guy who would be the world's greatest used car salesman...



Sorry but I never buy anything from anyone who can't/won't answer basic questions about the item...and I would never deal with any salesperson who'd displayed such passive aggression.

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## GrauGeist (Jul 21, 2021)

And like you, there's about a dozen others here who aren't buying his shi...err...sales pitch, either.
But on the interwebs, there's quite a few sites where the uninformed would gobble his nonsense up as gospel (in essence, buying that low-mileage 1978 Gremlin that was only owned by a little old lady) and they wouldn't be the wiser.


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## wuzak (Jul 21, 2021)

buffnut453 said:


> But the P-39C was a domestic model and it had the gas heater. @Shortround6 also provided pilot manuals for the D-1 and D-2 which also showed they had the gas heater.
> 
> Please provide a source for your assertion that the D had ducted air heating.



I would like to know how much this gas heater weighed.

It must have been in the hundreds of pounds, otherwise the British would not have specified it.

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## XBe02Drvr (Jul 21, 2021)

GrauGeist said:


> the uninformed would gobble his nonsense up as gospel (in essence, buying that low-mileage 1978 Gremlin that was only owned by* a little old lady*


*from Pasadena?*

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## SaparotRob (Jul 21, 2021)

buffnut453 said:


> See? We suck you in with platitudes and then get you addicted on actual information. Come to the dark side...we have cookies!!!
> 
> At least that's how it's SUPPOSED to work but some people seem immune!


I loved that tee-shirt!


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## SaparotRob (Jul 21, 2021)

GrauGeist said:


> And like you, there's about a dozen others here who aren't buying his shi...err...sales pitch, either.
> But on the interwebs, there's quite a few sites where the uninformed would gobble his nonsense up as gospel (in essence, buying that low-mileage 1978 Gremlin that was only owned by a little old lady) and they wouldn't be the wiser.


What color is the Gremlin?


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## Peter Gunn (Jul 21, 2021)

XBe02Drvr said:


> It's a manifestation of our sense of brotherhood and charity that we will put in all this effort to help our wayward member see the light, despite his mental attributes apparently resembling those of a creature whose contribution to the breakfast table we worship here, and whose feral cousin totes a 30MM firehose and hunts diesel armadillos for a living. Don't you find that honorable?


Uh... the... well... um...

Normally I grok the essence of your posts in their fullness but...

Huh?

As an aside, the DMV in Florida is A number 1. They get you in and out right quick, all modern with, and I know it's hard to believe, _helpful_ civil servant types behind the counter.

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## tyrodtom (Jul 21, 2021)

SaparotRob said:


> What color is the Gremlin?


They quit making Gremlins in 77, after that the cars that looked like Gremlins were called Spirit Kammbacks, or if 4x4, Eagle Kammback.
I've had a 77 Gremlin.

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## SaparotRob (Jul 21, 2021)

So this Gremlin must be Super Rare. The heck with the color.

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## Peter Gunn (Jul 21, 2021)

SaparotRob said:


> What color is the Gremlin?


Purple... it was purple.

100 years ago when I was a dumb teenager (is there any other kind), one of my buddies decided to drop a 327 Chevy in I think a 1974 purple Gremlin.

Nope. It could be done but I think it was determined he'd have to remove the front seats, and sit in back, change about everything yadda yadda yadda, long story short, you could make a bitchin' drag car out of it, but nothing street legal, at least now without a wheelbarrow full of money.

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## SaparotRob (Jul 21, 2021)

Peter Gunn said:


> Purple... it was purple.
> 
> 100 years ago when I was a dumb teenager (is there any other kind), one of my buddies decided to drop a 327 Chevy in I think a 1974 purple Gremlin.
> 
> Nope. It could be done but I think it was determined he'd have to remove the front seats, and sit in back, change about everything yadda yadda yadda, long story short, you could make a bitchin' drag car out of it, but nothing street legal, at least now without a wheelbarrow full of money.


True story. After a wonderful day, I'm driving my girlfriend home in my '91 Escort GT. She asked me what was I thinking about. I answered "what would it take to shoe horn a Ford 302 into this car". 
It stopped being a wonderful day.

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## tyrodtom (Jul 21, 2021)

Peter Gunn said:


> Purple... it was purple.
> 
> 100 years ago when I was a dumb teenager (is there any other kind), one of my buddies decided to drop a 327 Chevy in I think a 1974 purple Gremlin.
> 
> Nope. It could be done but I think it was determined he'd have to remove the front seats, and sit in back, change about everything yadda yadda yadda, long story short, you could make a bitchin' drag car out of it, but nothing street legal, at least now without a wheelbarrow full of money.


I guess I've got to eat a little crow.
1978 was the last year for the Gremlin name, after that that chassis was know as a Spirit.
And I thought I was a AMC expert.

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## SaparotRob (Jul 21, 2021)

Being wrong is part of being an Expert. Have you not been following this thread?

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## tyrodtom (Jul 21, 2021)

Oh yes I've been following it.
I think I've made some comments earlier in it, just didn't see the sense in saying anything lately.
Until someone mentioned a AMC product.
We've all got our priorities.

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## pbehn (Jul 21, 2021)

Is this the only thread on the forum where thread drift is encouraged and enjoyed?

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## SaparotRob (Jul 21, 2021)

Peter Gunn said:


> Uh... the... well... um...
> 
> Normally I grok the essence of your posts in their fullness but...
> 
> ...


I am only an egg.


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## wuzak (Jul 21, 2021)

Only 5 more posts to 150 pages?


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## SaparotRob (Jul 21, 2021)

I think we can...


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## SaparotRob (Jul 21, 2021)

.....get...


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## SaparotRob (Jul 21, 2021)

...close..


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## SaparotRob (Jul 21, 2021)

..to..


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## SaparotRob (Jul 21, 2021)

....150..


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## SaparotRob (Jul 21, 2021)

..pages.


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## SaparotRob (Jul 21, 2021)

pbehn said:


> Is this the only thread on the forum where thread drift is encouraged and enjoyed?


..especially if I reply to pbehn's post.

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## SaparotRob (Jul 21, 2021)

pbehn said:


> Is this the only thread on the forum where thread drift is encouraged and enjoyed?


Not the only thread. This one though, is definitely the front runner.


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## SaparotRob (Jul 21, 2021)

How many licks does it take to get to the center of a Tootsie Roll pop?

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## special ed (Jul 21, 2021)

The green Gremlin reminded me of a sort of friend who needed a car. I had a neighbor who bought a used 1975 AMC Pacer for his three sons to learn about cars. This was in the late 1990s. I called John to tell him I found a running car for $100 if he wanted it. His response, "What color is it?" I told him green and he said, "I guess I can paint it."

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## buffnut453 (Jul 21, 2021)

Hey fellas...this is the Groundhog thread. If all y'all want to establish a Gremlin thread, then go ahead. But let's stop this ridiculous thread drift, please!!!!

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## Bernhart (Jul 21, 2021)

and what's wrong with a green pacer? That was my first car

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## buffnut453 (Jul 21, 2021)

buffnut453 said:


> Hey fellas...this is the Groundhog thread. If all y'all want to establish a Gremlin thread, then go ahead. But let's stop this ridiculous thread drift, please!!!!



And please note my ability to speak Texan..."all y'all" being the plural of "y'all".

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## GregP (Jul 21, 2021)

It wasn't Olive Drab green, was it? 

If it had been, then it would have been camouflaged and you would not have seen it. Hey, nobody saw MOST Gremlins. They avoided them subconsciously.

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## GrauGeist (Jul 21, 2021)

Gremlins came in all different colors!

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## special ed (Jul 21, 2021)

The AMC Spirit was a gremlin with a rear end. My wife bought a 1980 with 232 six and with the distributer advanced, on premium gas, performed quite well. She didn't like my adjustment because it chirped the tires when she did a sudden acceleration so it had to go back stock.

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## buffnut453 (Jul 21, 2021)

GrauGeist said:


> Gremlins came in all different colors!
> 
> View attachment 633168



Those are not representative images of gremlins. You have to go to the original source material, written by Roald Dahl, to get it right:


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## SaparotRob (Jul 21, 2021)

GrauGeist said:


> Gremlins came in all different colors!
> 
> View attachment 633168


Are those Gremlins from the Kremlin?


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## 33k in the air (Jul 21, 2021)

SaparotRob said:


> What color is the Gremlin?



The most important rules about the Gremlin:

(1) Don't take it out during the day.
(2) Don't wash it or drive it when it's raining.
(3) Don't fill it up with gasoline after midnight.

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## GrauGeist (Jul 21, 2021)

SaparotRob said:


> Are those Gremlins from the Kremlin?


From Warner Brothers studios - so I'd say they're "Burbank Gremlins"

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## SaparotRob (Jul 21, 2021)

I believe it's entitled "Gremlins from the Kremlin". You might also want to see the aviation documentary "Falling Hare", Warner Brothers 1942(?) for more information on Gremlins.

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## GrauGeist (Jul 21, 2021)

"Russian Rhapsody", 1944

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## tyrodtom (Jul 21, 2021)

I think I've seen both of those when I was a kid. 
They were very alike except for the ending.
In one the aircraft falls in a screaming dive, stops about 5 feet up from the ground, Bugs Bunny jumps out, and says " out of gas "

The next one same screaming dive, again stops about 5 feet up. This time Bugs jumps out and tells us, " air brakes "

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## SaparotRob (Jul 21, 2021)

GrauGeist said:


> "Russian Rhapsody", 1944


You are right. They were singing "We're Gremlins from the Kremlin".


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## GrauGeist (Jul 21, 2021)

Russian Rhapsody was the one where the Gremlins were harassing Hitler, too.

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## SaparotRob (Jul 21, 2021)

Is this the one where, when Daffy is being pursued by Hitler and Mussolini, puts a Stalin mask and terrifies the two?


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## GrauGeist (Jul 21, 2021)

SaparotRob said:


> Is this the one where, when Daffy is being pursued by Hitler and Mussolini, puts a Stalin mask and terrifies the two?


I think that's the one where he's a commando and first confronts a raven who's a German officer wearing a monocle.


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## SaparotRob (Jul 21, 2021)

No that's a different one. Commando Daffey? There was a smaller bird named Schultz who was always getting clobbered by the officer. It's been a long time since I've seen those. I think I'm going to look them up.


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## buffnut453 (Jul 21, 2021)

And another 3 pages have been added with no answer to my post #2746.

Sorry for such boring posts but I keep hoping to get an answer.

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## SaparotRob (Jul 21, 2021)

It keeps us grounded.

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## SaparotRob (Jul 21, 2021)

GrauGeist said:


> I think that's the one where he's a commando and first confronts a raven who's a German officer wearing a monocle.


I just looked it up. That's Daffey the Commando. His foil is Uberkomt von Vultur. 
In Russian Rhapsody, it's 3 gremlins who put on the Stalin mask. 
Best. Research. Ever.

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## GregP (Jul 21, 2021)

Hey Buffnut, if he doesn't answer questions that put a bad light on either the P-39 or himself for being wrong, what makes you think he'll ever answer your request for a sources on the gas heater in a P-39D?

Doesn't really need an answer. I think we understand the lack of enthusiasm for a reply since perhaps there IS no source. On the other hand, perhaps he'll surprise us all and chime in with one. Still, it won't turn a sow's ear P-39 into silk purse fighter. All it can do is kill the pilot with carbon monoxide poisoning, and do it while being very heavy and sapping otherwise potential war winning performance, nose armor aside ... maybe even 498 mph .... nnaaahhhhhhh. It's a P-39, for crying out loud.

Maybe this will help:







I'm starting to like it better than the P-39. At least it's an honest airplane that won't tumble and roll and dig a big hole.

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## buffnut453 (Jul 21, 2021)

GregP said:


> Hey Buffnut, if he doesn't answer questions that put a bad light on either the P-39 or himself for being wrong, what makes you think he'll ever answer your request for a sources on the gas heater in a P-39D?
> 
> Doesn't really need an answer. I think we understand the lack of enthusiasm for a reply since perhaps there IS no source. On the other hand, perhaps he'll surprise us all and chime in with one. Still, it won't turn a sow's ear P-39 into silk purse fighter. All it can do is kill the pilot with carbon monoxide poisoning, and do it while being very heavy and sapping otherwise potential war winning performance, nose armor aside ... maybe even 498 mph .... nnaaahhhhhhh. It's a P-39, for crying out loud.
> 
> ...



Welcome to the dark side. Here...have a cookie!

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## P-39 Expert (Jul 21, 2021)

wuzak said:


> I believe the British corrected performance to 95% of gross weight. Not tested at 95% gross weight, since the weight varied during a test flight.


Exactly what I have been saying, tested at gross weight but test weight listed as 95% of gross to approximate average fuel during the flight.

Thank you.


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## P-39 Expert (Jul 21, 2021)

GregP said:


> Hey Buffnut, if he doesn't answer questions that put a bad light on either the P-39 or himself for being wrong, what makes you think he'll ever answer your request for a sources on the gas heater in a P-39D?
> 
> Doesn't really need an answer. I think we understand the lack of enthusiasm for a reply since perhaps there IS no source. On the other hand, perhaps he'll surprise us all and chime in with one. Still, it won't turn a sow's ear P-39 into silk purse fighter. All it can do is kill the pilot with carbon monoxide poisoning, and do it while being very heavy and sapping otherwise potential war winning performance, nose armor aside ... maybe even 498 mph .... nnaaahhhhhhh. It's a P-39, for crying out loud.
> 
> ...


What sources do you need? The pilot's manuals say the gas heater was in the export models (P-400, P-39D1 and D2) and the rest (D/F/K/L/M/N/Q) had the ducted air system.


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## buffnut453 (Jul 21, 2021)

P-39 Expert said:


> What sources do you need? The pilot's manuals say the gas heater was in the export models (P-400, P-39D1 and D2) and the rest (D/F/K/L/M/N/Q) had the ducted air system.



And what about the P-39C? Pilot's Manual says that had the gas heater and it wasn't an export version.


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## P-39 Expert (Jul 21, 2021)

Shortround6 said:


> No, you can't do it that way.
> 
> It doesn't take into account the different internal friction and supercharger drive requirements.
> 
> ...


Because the only difference in fuel consumption at 25000' is RPM. Throttle set at full, mixture at auto rich. No other changes except going from 2600rpm to 3000rpm. Your figures at 14000'-15000' have no relevance to fuel consumption at 25000'.

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## Thumpalumpacus (Jul 21, 2021)

buffnut453 said:


> And another 3 pages have been added with no answer to my post #2746.
> 
> Sorry for such boring posts but I keep hoping to get an answer.



As I wrote in a song long ago, "Silence says so much."

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## Thumpalumpacus (Jul 21, 2021)

SaparotRob said:


> It keeps us grounded.



Quit hogging all the puns, man!

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## pbehn (Jul 21, 2021)

P-39 Expert said:


> Exactly what I have been saying, tested at gross weight but test weight listed as 95% of gross to approximate average fuel during the flight.
> 
> Thank you.


The P-51 D ended up with 465 gallons of fuel 6 MGs with ammunition, enough oil for an 8 hr mission at least, tail warning radar etc, the D was slightly heavier and slower than the B/C but thats exactly what the client wanted, why do you keep quibbling about small weight differences?

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## GrauGeist (Jul 21, 2021)

P-39 Expert said:


> Because the only difference in fuel consumption at 25000' is RPM. Throttle set at full, mixture at auto rich. No other changes except going from 2600rpm to 3000rpm. Your figures at 14000'-15000' have no relevance to fuel consumption at 25000'.


Are these the settings you used when you flew it?

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## buffnut453 (Jul 21, 2021)

GrauGeist said:


> Are these the settings you used when you flew it?



Not in formation, that's for damn sure.

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## Shortround6 (Jul 21, 2021)

P-39 Expert said:


> Because the only difference in fuel consumption at 25000' is RPM. Throttle set at full, mixture at auto rich. No other changes except going from 2600rpm to 3000rpm. Your figures at 14000'-15000' have no relevance to fuel consumption at 25000'.



Hmmm, the figures at 14000-15,000ft were ALL at full throttle, mixture set at auto rich. They do show a pattern. So will every other aircraft engine. 

Don't tell me I am wrong, show me I am wrong. Tell me where the power to overcome the increased internal friction and the increased power to turn the supercharger comes from? 

The figures from the mid teens show a 26.6 % increase in fuel consumption going from 2600rpm to 3000rpm for a 12.5% increase in power.

power at 25,000ft for an Allison with 9.60 supercharger gears and no RAM at 2600rpm was about 670hp. You want a10.4% to 15% increase in power for a 15% increase in fuel consumption. NO other aircraft engine I know of could do that.

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## FLYBOYJ (Jul 21, 2021)

P-39 Expert said:


> Because the only difference in fuel consumption at 25000' is RPM. Throttle set at full, mixture at auto rich. No other changes except going from 2600rpm to 3000rpm. Your figures at 14000'-15000' have no relevance to fuel consumption at 25000'.


 Pixie Dust, unicorn poop or Groundhog mystical incantations


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## SaparotRob (Jul 21, 2021)

Power is out from a lightning strike. No desktop. Glad I charged the phone.

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## SaparotRob (Jul 21, 2021)

Thumpalumpacus said:


> Quit hogging all the puns, man!


You weren’t around!


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## SaparotRob (Jul 21, 2021)

Power is back! My wife has internet again. I might live another day!

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## pbehn (Jul 21, 2021)

P-39 Expert said:


> Because the only difference in fuel consumption at 25000' is RPM. Throttle set at full, mixture at auto rich. No other changes except going from 2600rpm to 3000rpm. Your figures at 14000'-15000' have no relevance to fuel consumption at 25000'.


Do you realise how funny that is, you may think changing RPM is a small thing, it changes everything. If a supercharger, engine and propeller are past optimum altitude, increasing RPM just makes the problems worse not better, like flooring the throttle when your wheels start spinning on snow.

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## Thumpalumpacus (Jul 21, 2021)

Shortround6 said:


> Hmmm, the figures at 14000-15,000ft were ALL at full throttle, mixture set at auto rich. They do show a pattern. So will every other aircraft engine.
> 
> Don't tell me I am wrong, show me I am wrong. Tell me where the power to overcome the increased internal friction and the increased power to turn the supercharger comes from?
> 
> ...



It would appear that someone hasn't heard of the Second Law of Thermodynamics.


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## Thumpalumpacus (Jul 21, 2021)

SaparotRob said:


> Power is out from a lightning strike. No desktop. Glad I charged the phone.



No worries, you're not the only one phoning it in, in this thread, clearly.

I'm up 2-1 in punnery!

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## P-39 Expert (Jul 21, 2021)

GregP said:


> Hey pben.
> 
> He gets it from the P-39Q manual, page 25, chart for 8100 to 7200 pounds ,with 75 gal external tank. First set of columns, there is an entry for 25,000 feet. It says 2600 rpm, 267 mph T.A.S., Full Throttle, 62 U.S. gallons per hour (max continuous power). The climb data from the same manual says it will climb at 750 fpm at 135 mph in a combat climb and 650 fpm at 140 mph in a ferry climb at 25,000 feet. Combat missions were at 3000 rpm and 44..5 " MAP. Ferry mission were at 2300 rpm, 31" MAP (page 23).
> 
> ...


You went to a whole lot of trouble to quote combat radius on 87gal internal and a 75gal drop tank. All P-39s would hold 120gal internal and carry a 110gal drop tank, same as what was at the fighter bases in east England. 

And don't climb to 25000' at combat setting (careful, Flyboy doesn't know what that means, he can't find it quoted anywhere), use the ferry setting so that it takes you 31min and you don't burn up your engine. And you will have traveled 110mi (170IAS average = 220mphTAS). But don't figure that into your range because you may not be heading to your target.

Learn how to use the Flight Operation Instruction Chart (range chart). It doesn't include any figures from the Takeoff, Climb and Landing chart. Total fuel 230gal, less takeoff and climb reserve 20gal, 20min combat at 25000' 25gal, and 20min landing reserve 10gal leaving 175gal. Divide that by 62GPH = 2.8hrs flying time x 267mphTAS = 748mi. Divide by 2 for radius 374mi. Warmup and takeoff on internal, switch to drop tank as soon as gear/flaps are up and climb speed is reached. Simple form up as lead pair take a wide turn to target vector and the 7 following pairs make progressively narrower turns to form up the 16 plane squadron and vector to target. Cruise starts even before the 20gal T/O/Climb allowance has gotten you to 5000' as your climb to 25000' is on target heading. Drop tank fuel 90gal (110gal less 20gal T/O reserve) gets 387mi (90 divided by 62gph = 1.45hrs x 267mph). When the drop tank runs dry switch to internal and start home. If combat occurs and the drop tank is dropped before it is empty then combat radius will be shorter, just like any fighter carrying a drop tank. If combat occurs just as the drop tank runs dry then deduct combat allowance 25gal and landing reserve 10gal from the 120gal internal fuel (85gal left) and come home at 330TAS (85 divided by 62GPH = 1.4HR x 330mphTAS = 452mi).

Learn how to use the correct chart, it's much easier to use and more accurate.

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## SaparotRob (Jul 21, 2021)

I think I just read the funniest post. I can’t top that.

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## pbehn (Jul 21, 2021)

P-39 Expert said:


> You went to a whole lot of trouble to quote combat radius on 87gal internal and a 75gal drop tank. All P-39s would hold 120gal internal and carry a 110gal drop tank, same as what was at the fighter bases in east England.
> 
> And don't climb to 25000' at combat setting (careful, Flyboy doesn't know what that means, he can't find it quoted anywhere), use the ferry setting so that it takes you 31min and you don't burn up your engine. And you will have traveled 110mi (170IAS average = 220mphTAS). But don't figure that into your range because you may not be heading to your target.
> 
> ...


After combat, can you land and put the tank back on, to keep your combat radius? I am thinking outside of the box here.

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## GrauGeist (Jul 21, 2021)

P-39 Expert said:


> careful, Flyboy doesn't know what that means, he can't find it quoted


*Show us* where that phrase is used in any manufacturer's or military publication.

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## pbehn (Jul 21, 2021)

SaparotRob said:


> I think I just read the funniest post. I can’t top that.


It is descending into "Blackadder" humour. "When your external tank runs dry go home, if you experience combat before external tanks run dry, have a little combat then go home"

Er what about those 600 bombers with a crew of 10 or more that you ust left alone over Germany?

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## Glider (Jul 21, 2021)

P-39 Expert said:


> You went to a whole lot of trouble to quote combat radius on 87gal internal and a 75gal drop tank. *All P-39s would hold 120gal internal* and carry a 110gal drop tank, same as what was at the fighter bases in east England.


My understanding was that the P39N (the one you always seem to quote) normally carried approx 80 gallons internally instead of the 120 gallons to reduce weight and improve performance.

So make up your mind. Either :-
a) Use the smaller tank when discussing range or
b) Use the lower performance when discussing performance
c) Try and respond to some of the many questions people have asked you

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## FLYBOYJ (Jul 21, 2021)

P-39 Expert said:


> And don't climb to 25000' at combat setting (careful, Flyboy doesn't know what that means, he can't find it quoted anywhere)


Yep - because it's a BS term made up by you "(in balance", "tail cone", etc.) Show us in the Flight Manual where that term is?!?!?!?


P-39 Expert said:


> Learn how to use the correct chart, it's much easier to use and more accurate.


I think you've been shown by at least 4 people on here that it's YOU who doesn't know how to use the chart and I'm still waiting to hear about a cross country flight you planned and flew using similar charts!!!

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## 33k in the air (Jul 21, 2021)

pbehn said:


> Er what about those 600 bombers with a crew of 10 or more that you ust left alone over Germany?



They'll be fine! After all, they've got lots of guns with which to defend themselves.

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## FLYBOYJ (Jul 21, 2021)

P-39 Expert said:


> You went to a whole lot of trouble to quote combat radius on 87gal internal and a 75gal drop tank. All P-39s would hold 120gal internal and carry a 110gal drop tank, same as what was at the fighter bases in east England.
> 
> And don't climb to 25000' at combat setting (careful, Flyboy doesn't know what that means, he can't find it quoted anywhere), use the ferry setting so that it takes you 31min and you don't burn up your engine. And you will have traveled 110mi (170IAS average = 220mphTAS). But don't figure that into your range because you may not be heading to your target.
> 
> ...

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## pbehn (Jul 21, 2021)

33k in the air said:


> They'll be fine! After all, they've got lots of guns with which to defend themselves.


I'm so glad it is just an academic discussion.

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## GrauGeist (Jul 21, 2021)

WOW...ok, I did a bit of searching on the interwebs for this mysterious throttle setting called "Combat Power" and lo and behold, I found it!

In a wargaming forum for IL-2 Sturmovik.

About the 20th post down, the guy is roasting the P-39 for poor performance (gasp) and this quote is from their post:


> Dogfighting on *combat power* is equally frustrating, and I constantly find opponents slipping away in situations where I would certainly have caught them in a Yak or MiG.


_(See the full conversation here: Thoughts on the P39...)_

So now it seems rather clear how "someone" got their credentials with the Bell Product.

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## SaparotRob (Jul 21, 2021)

That deserves another bacon.


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## FLYBOYJ (Jul 21, 2021)

GrauGeist said:


> WOW...ok, I did a bit of searching on the interwebs for this mysterious throttle setting called "Combat Power" and lo and behold, I found it!
> 
> In a wargaming forum for IL-2 Sturmovik.
> 
> ...


Amazing! I bet you can also find "Flux Capacitor" in there as well!

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## pbehn (Jul 21, 2021)

As long as the dilithium crystals hold we can bypass the flux capacitors and maintain warp drive... ... captain.

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## GrauGeist (Jul 21, 2021)

FLYBOYJ said:


> Amazing! I bet you can also find "Flux Capacitor" in there as well!


Or find the missing cockpit heater

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## 33k in the air (Jul 21, 2021)

pbehn said:


> I'm so glad it is just an academic discussion.



Indeed! Now let's get back to more weighty matters, such as Gremlins!




FLYBOYJ said:


> Amazing! I bet you can also find "Flux Capacitor" in there as well!



Just don't fly at 88 MPH or else . . . things happen. Lt. McFly can tell you more.

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## FLYBOYJ (Jul 21, 2021)

33k in the air said:


> Just don't fly at 88 MPH or else . . . things happen. Lt. McFly can tell you more.


Maybe we can get to 25,000' on 20 gallons!


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## pbehn (Jul 21, 2021)

FLYBOYJ said:


> Maybe we can get to 25,000' on 20 gallons!


The contents of an urchin shaped cod piece gets me to 25,000ft.

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## 33k in the air (Jul 21, 2021)

FLYBOYJ said:


> Maybe we can get to 25,000' on 20 gallons!



No, to the Moon!

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## Thumpalumpacus (Jul 21, 2021)

pbehn said:


> After combat, can you land and put the tank back on, to keep your combat radius? I am thinking outside of the box here.



You could always link up with a KB-50 and top off to get home. I mean, if we can time-machine P-39 models, certainly we can time-machine aerial refuellers. Maybe remove the cannon in the spinner and replace it with plumbing to get the groundhog home?

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## FLYBOYJ (Jul 21, 2021)

Thumpalumpacus said:


> You could always link up with a KB-50 and top off to get home. I mean, if we can time-machine P-39 models, certainly we can time-machine aerial refuellers. Maybe remove the cannon in the spinner and replace it with plumbing to get the groundhog home?


Just don't removed the gearbox armor

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## Thumpalumpacus (Jul 21, 2021)

FLYBOYJ said:


> Just don't removed the gearbox armor



What else will protect the plumbing?!

Get real, brotha!

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## nuuumannn (Jul 21, 2021)

P-39 Expert said:


> The question was could it escort bombers in Europe. I have proven that many times by using information from the pilot's manual.



As another contributor asked way back, I wanna know why it wasn't used as such. What could you have possibly found that the 8th AF didn't in 1943?

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## FLYBOYJ (Jul 21, 2021)

Thumpalumpacus said:


> *What else will protect the plumbing?!*
> 
> Get real, brotha!


 Groundhog mystical incantations

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## Thumpalumpacus (Jul 21, 2021)

nuuumannn said:


> As another contributor asked way back, I wanna know why it wasn't used as such. What could you have possibly found that the 8th AF didn't in 1943?



For one thing, those dumbasses didn't have the Interwebz.

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## nuuumannn (Jul 21, 2021)

Thumpalumpacus said:


> For one thing, those dumbasses didn't have the Interwebz.



Or the IL-2 video game, apparently...

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## GrauGeist (Jul 21, 2021)

Thumpalumpacus said:


> You could always link up with a KB-50 and top off to get home. I mean, if we can time-machine P-39 models, certainly we can time-machine aerial refuellers. Maybe remove the cannon in the spinner and replace it with plumbing to get the groundhog home?


Problem is, the KB-50 cruises at about 245 miles an hour.
The illustrious P-39 would have to step up their game to get in behind the tanker (while being slapped bat-sh!t silly by the wake) and make a connection.


Of course, there's obviously only one person who could pull it off and we're blessed to have him in our midst...

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## Shortround6 (Jul 21, 2021)

The "expert" doesn't seem to grasp that the drop tank is immaterial. 
Hang a 110 gallon tank on the P-39 and you might wind up in place you can't get home from.

You are down 10-15 gallons of internal fuel after warm up, take off and climb to safe height to switch tanks. 

Now what is critical is how much fuel is remaining in the the internal tanks after 15-20 minutes of combat and allowing for a* 30 minute reserve*. 

That is the fuel available for egress from the combat area. 

what was in the drop tank is smoke and mirrors. 

Give him the 120 gallon fuel capacity, he is down to 105-110 when the tank (of whatever size ) is punched off. The P-39 with a tank attached is just a target for the Luftwaffe fighters. 
30 minute reserve to get home is around 15 gallons. Down to 90-95 gallons. 

Now the much debated combat allowance. 
If the P-39s can defend the bombers by flying straight and level for 20 minutes they just might squeak out just over 30 gallons of fuel used in "combat". 

If they have to do anything else, like turn, then the bets are off and the P-39s will not be able to stay at 25,000ft. The lower it goes the more fuel per minute it burns. 

Unfortunately some of the P-39 charts are sheer nonsense. Both the take-off an climb charts and the range charts. 

However the P-39 and other aircraft "fight operation instruction chart/s" do have a phrase/sentence that the "expert" has completely over looked.

In the box near the top that says "instructions for using chart" when you get to the notes, note "A" says...

"AVOID CONTINOUS CRUISING IN COLUMN 1 EXCEPT IN EMERGENCY"

The "expert's" entire flight plan except for landing is based around continuous cruise in Column 1 conditions.

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## Thumpalumpacus (Jul 21, 2021)

Shortround6 said:


> The "expert" doesn't seem to grasp that the drop tank is immaterial.
> Hang a 110 gallon tank on the P-39 and you might wind up in place you can't get home from.
> 
> You are down 10-15 gallons of internal fuel after warm up, take off and climb to safe height to switch tanks.
> ...



On the other hand, the Groundhog can tunnel home and bombers be damned.

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## Shortround6 (Jul 21, 2021)

FLYBOYJ said:


> Maybe we can get to 25,000' on 20 gallons!


Why not????
we have a P-39N chart that "says" it can go from 5,000ft to 25,000ft at 8,000lbs in 24.9 minutes using 2300rpm and 32 in MAP while only using 4.4 gallons of fuel

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## wuzak (Jul 21, 2021)

P-39 Expert said:


> You went to a whole lot of trouble to quote combat radius on 87gal internal and a 75gal drop tank. All P-39s would hold 120gal internal and carry a 110gal drop tank, same as what was at the fighter bases in east England.
> 
> And don't climb to 25000' at combat setting (careful, Flyboy doesn't know what that means, he can't find it quoted anywhere), use the ferry setting so that it takes you 31min and you don't burn up your engine. And you will have traveled 110mi (170IAS average = 220mphTAS). But don't figure that into your range because you may not be heading to your target.
> 
> ...



I think it is best for you to show your workings graphically.

That is, post pictures of the chart your using and highlight the sections where you source your numbers.

PS you assume that the P-39 has 120 USG of internal fuel, when most of later models had only 87 from the factory. There were kits to bring them back up to 120 USG, but how many were made and installed. But how did that effect weight and performance?

Sure, if they were going to be used for escort they would likely get the extra tankage.

I think there was on squadron sent to Britain as part of the 8th FC, but they quickly swapped them for Spitfire Vs. What were they thinking?


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## FLYBOYJ (Jul 21, 2021)

Shortround6 said:


> The "expert's" entire flight plan except for landing is based around continuous cruise in Column 1 conditions.


And in most cases not flying over 5000'


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## FLYBOYJ (Jul 21, 2021)

Shortround6 said:


> Why not????
> we have a P-39N chart that "says" it can go from 5,000ft to 25,000ft at 8,000lbs in 24.9 minutes using 2300rpm and 32 in MAP while only using *4.4 gallons of fuel *


That's better than the 160 HP C172 with an O-320 that I fly!

Pixie Dust, Unicorn Poop, Groundhog mystical incantations


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## Shortround6 (Jul 21, 2021)

FLYBOYJ said:


> And in most cases not flying over 5000'



I think he very much plans to fly at 25,000ft, he just doesn't explain how his planes get there  

His whole premise seems to be built around the speed in the chart the P-39 (without drop tank) can fly while the engine gasps for air at 25,000ft.
If he drops to 20,000ft the plane is slower and burns more fuel per hour and at 15,000ft the plane is slower yet while burning 66% more fuel per hour than 25,000ft.

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## FLYBOYJ (Jul 21, 2021)

Shortround6 said:


> I think he very much plans to fly at 25,000ft, he just doesn't explain how his planes get there


Exactly! 


Shortround6 said:


> His whole premise seems to be built around the speed in the chart the P-39 (without drop tank) can fly while the engine gasps for air at 25,000ft.
> If he drops to 20,000ft the plane is slower and burns more fuel per hour and at 15,000ft the plane is slower yet while burning 66% more fuel per hour than 25,000ft.


I think we both know by now that there are errors in those charts, this was mentioned several times during this ordeal but there is some data that is somewhat useable. What is interesting to compare some of the chart information against the performance tests at P-39 Performance Tests, but I think you have mentioned this pages ago.

But I think our friend will only bring that up if it enforces his arguments!

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## Shortround6 (Jul 21, 2021)

FLYBOYJ said:


> That's better than the 160 HP C172 with an O-320 that I fly!
> 
> Pixie Dust, Unicorn Poop, Groundhog mystical incantations


Lots of misprints and typos. It should have been 14.4 gallons which is still rather astonishing. Under 0.6 gallon per minute while flying around 200mph and climbing 20,000ft in 24.9 minutes.

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## wuzak (Jul 21, 2021)

919 posts to get to page 200.

Another 3 1/2 pages appeared when I was sleeping. Mostly about Gremlins, it seems, until the topic drifted into talking about a P-39 airplane.

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## XBe02Drvr (Jul 22, 2021)

nuuumannn said:


> As another contributor asked way back, I wanna know why it wasn't used as such. What could you have possibly found that the 8th AF didn't in 1943?


They listened to the RAF, who had it in for Larry Bell, didn't you know?


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## XBe02Drvr (Jul 22, 2021)

Thumpalumpacus said:


> On the other hand, the Grounhog can tunnel home and bombers be damned...


...unless they're toting Tallboys, then all bets are off.

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## XBe02Drvr (Jul 22, 2021)

Thumpalumpacus said:


> Maybe remove the cannon in the spinner and replace it with plumbing to get the groundhog home?


Oh goody! I love fireworks displays!

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## GregP (Jul 22, 2021)

P-39 Expert said:


> You went to a whole lot of trouble to quote combat radius on 87gal internal and a 75gal drop tank. All P-39s would hold 120gal internal and carry a 110gal drop tank, same as what was at the fighter bases in east England.
> 
> And don't climb to 25000' at combat setting (careful, Flyboy doesn't know what that means, he can't find it quoted anywhere), use the ferry setting so that it takes you 31min and you don't burn up your engine. And you will have traveled 110mi (170IAS average = 220mphTAS). But don't figure that into your range because you may not be heading to your target.
> 
> ...


Hi P-39 Expert.

My P-39Q POH manual says 87 gallons. It's a pdf available online. Here is the address:

https://airandspace.si.edu/webimages/collections/full/Pilot's%20flight%20manual%20for%20P-39%20Airacobra.pdf

Look on page 21. 87 gallons for the P-39Q. That's why I used 87 gallons. I just picked a manual, I didn't deliberately cherry-pick one with less fuel.

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## SaparotRob (Jul 22, 2021)

To quote Packard; "Ask the man who owns one".

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## Peter Gunn (Jul 22, 2021)

33k in the air said:


> No, to the Moon!


So says the Chairman of the Board:

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## Peter Gunn (Jul 22, 2021)

SaparotRob said:


> Power is back! *My wife has internet again. I might live another day!*


As long as you don't compare her to a Ford V8 that is...

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## SaparotRob (Jul 22, 2021)

Peter Gunn said:


> As long as you don't compare her to a Ford V8 that is...


I learned that lesson.

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## Milosh (Jul 22, 2021)

Peter Gunn said:


> As long as you don't compare her to a Ford V8 that is...


yes, FixOrRepairDaily doesn't go over well.

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## pbehn (Jul 22, 2021)

OMG I just used this thread as a source.

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## Peter Gunn (Jul 22, 2021)

pbehn said:


> OMG I just used this thread as a source.


I hate to say this but I think you need to see a doctor.

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## GrauGeist (Jul 22, 2021)

pbehn said:


> OMG I just used this thread as a source.


What part, the Gremlins?

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## GregP (Jul 22, 2021)

I checked my P-39N-0 and N-1 manual. It says 87 gallons internal, too. Then I checked my P-39K manual. It says 104 gallons internal + 16 gallons internal overload, for 120 gallons.

Let's see. They built 9,558 to 10,092 P-39 Airacobras. The P-39N accounted for 2,095 of them. The P-39Q accounted for 4,905 of them. That's 7,000 P-39s in the Q and N models alone, or 73% of them if you use the 9,558 build total.

They built 210 P-39K models. That's 2.2%. Not exactly the "mass-production model," is it?

The vast majority of P-39s that got sent anywhere had 87 gallons of internal fuel and about 2% of them held 120 gallons internal fuel if you look only at the K models. I decline to look any farther into the other 25% of P-39's. Feel free. But, and here's the thing to notice, the 87-gallon models were built AFTER the P-39K's were built.

Maybe they found out that the 120 gallons of internal fuel were just too much for the airplane to fighter well with? Whatever the reason, the later P-39s did not hold 120 gallons.

Methinks you are cherry-picking again, trying desperately to use the absolute lightest P-39 you can find, with the highest internal fuel tankage you can find, and then use the highest speed and climb numbers you can find along with the longest range you can find.

The things is, these things above did not happen on the same model P-39. You need to choose a single model, accept the weight, accept the fuel specified, and accept the numbers that aren't in column 1 of the cruise charts. You also need to accept that the P-39 didn't fight very much at 25,000 feet. It was in its element at 12,000 feet and below. Maybe 15,000 at the highest. It was mainly seen within 175 miles from the departure point.

But, I'm pretty sure you will ignore this and continue to claim 120 gallons of internal fuel. After all, it's in the simulator, right?

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## buffnut453 (Jul 22, 2021)

Well, having received an answer (not a particularly good one since, again, it missed a key part of the question) for my post #2746, I'm now counting pages since my last question at post #3011....three have gone past so far. 

I'm reminded of the great quote by the author Douglas Adams "I love deadlines. I love the whooshing noise they make as they go by." Can we implement a whooshing noise as each new page is added to a thread we're watching?

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## 33k in the air (Jul 22, 2021)

Peter Gunn said:


> So says the Chairman of the Board:



Originally it was to be sung as "Fly me to the moon on 20 gallons of gas" but he had the good sense to change that part of the lyrics.

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## FLYBOYJ (Jul 22, 2021)

GregP said:


> Methinks you are cherry-picking again, trying desperately to use the absolute lightest P-39 you can find, with the highest internal fuel tankage you can find, and then use the highest speed and climb numbers you can find along with the longest range you can find.
> 
> But, I'm pretty sure you will ignore this and continue to claim 120 gallons of internal fuel. After all, it's in the simulator, right?


BINGO!!!!

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## Shortround6 (Jul 22, 2021)

The "D"s all had 120 gallons, the K & L & M all had 120 gallons.

The Q-1 had 87 gallons.
The Q -5 had 110 gallons (?)
The Q-10/-15/-20/-30 all had 120 gallons. 

120 gallons was quite doable. (leave out the wing guns for weight compensation  )

However the whole thing is based off the "N" and one extraordinarily good test and a one or two strange numbers in the flight charts. 

A P-39 with a drop tank, no matter what model, is not fast enough at altitude to do escort work. The P-38 and P-47 could cruise at over 300mph at 25,000ft with drop tank/s attached and not use column 1 on the charts. 
A P-39 without drop tank, no matter what model, is 20-40mph slower than the P-38s and P-47s of mid 1943 and slower than the 109s. at the altitude the bombers are flying at. 
A P-39, no matter what model, at 20,000ft and above has the worst power to weight ratio of the available allied fighters and of the defending fighters. 

the P-39 is a low drag airplane and can reach a pretty good speed if given enough time. But it can't bleed off speed in maneuvers and get it back quick. 
P-39 as a bomber escort for B-17s would be of less use than the Bf 110 was to the Germans in 1940.

Heck, stick a 25imp gallon tank in the back of a Spitfire IX and a 90 gallon tank under it and you would have a better escort fighter than a P-39. 

They did wind up sticking a 41 gallon and a 33 gallon tank in the back of Spitfire IX so it was _possible. Maybe not a good idea but possible. _

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## pbehn (Jul 22, 2021)

Shortround6 said:


> A P-39 with a drop tank, no matter what model, is not fast enough at altitude to do escort work. The P-38 and P-47 could cruise at over 300mph at 25,000ft with drop tank/s attached and not use column 1 on the charts.
> 
> 
> They did wind up sticking a 41 gallon and a 33 gallon tank in the back of Spitfire IX so it was _possible. Maybe not a good idea but possible. _


A P-39 that just dropped it's tank was 10mph slower at all engine settings than a P-39 that never had one fitted, stated in the frequently quoted tests)

The main tanks of a Spitfire were increased from 85 to 95 gallons with the two speed supercharger. They could and did also put 25 gallons in the wings (12.5 in each) plus as you say a rear tank which was fitted in some especially the MkXIV. So 120 gallons plus is easily possible in the Spitfire. BUT any reading even on wiki explains that the extra 10 gallons in the Spitfire main tanks didnt increase range or endurance, it just did everything more quickly. Only the P-39 gets the free lunch where it cruises at 95% of its top speed and uses 1/3 of its maximum power/fuel consumption even with a huge tank strapped underneath.

Are any of the performance figures at 25,000ft with 100gallons of fuel on board, as in external tank just dropped?

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## Shortround6 (Jul 22, 2021)

A P-40F at 25,000ft had almost 10% more power when climbing than the P-39N and that is the P-40F running at 2850rpm and the P39N using 3000rpm.

Nobody was suggesting using the the P-40F as an escort fighter. 

See this report for P-40 numbers. 


http://www.wwiiaircraftperformance.org/P-40/P-40F_41-13635_FS-M-19-1578-A.pdf

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## FLYBOYJ (Jul 22, 2021)

pbehn said:


> A P-39 that just dropped it's tank was 10mph slower at all engine settings than a P-39 that never had one fitted, stated in the frequently quoted tests)


And that probably due to the installation of the braces to hold the tank


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## pbehn (Jul 22, 2021)

FLYBOYJ said:


> And that probably due to the installation of the braces to hold the tank


It is specifically tested, without shackles, with shackles and with shackles and tank full (tank is 75gal type) 10MPH is a ball park figure but all figures are around that, and probably within experimental error. Tests at 13,000ft.









  Belly Tank
Brackets &
Shackles
Removed MPH​Belly Tank
Removed
Shackles &
Brackets
in Place MPH​Belly Tank (Full)
Shackles & Brackets
in Place MPH​RPM​Chart
BHP​Throttle
Position​Mixture setting​  358​-​-​3000​1170​W.O.​A.R.​ 336.5​328​-​2600​974​W.O.​A.R.​ -​349​-​3000​1165​W.O.​A.R.​ -​-​311.5​3000​1145​W.O.​A.R.​ -​-​294.5​2600​967​W.O.​A.R.​ 321.5​312.5​282​2280​850​Part​A.L.​ 301​292​264​2200​700​Part​A.L.​ 276​267​241​2100​550​Part​A.L.​ 257​247​221​1900​450​Part​A.L.​ 222​212​184​1700​330​Part​A.L.​

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## GrauGeist (Jul 22, 2021)

Even the Allison powered Mustang was at a disadvantage at higher altitudes (also why it wasn't used as escort) much like the Fw190, who like the Merlin powered Mustangs, required an entirely different engine in order to be effective at typical altitudes used by bombers.

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## FLYBOYJ (Jul 22, 2021)

Some observations:

I've been going through the P-39N and Q manuals and been finding some "hokey" things in both (Imagine that). In the performance charts I can easily see how someone with little or no flight or aviation experience can be misled with some of the data, especially if you have conflicting information.

First, flight planning 101 -* you use BOTH climb and cruise charts, end of story!* The comment on the Flight Operation Instruction Sheet about using 20 gallons for fuel for taxi, warm-up and climb to 5000' is actually wrong and should be removed as if conflicts with the climb data sheet on P 26. Now if you look at the flight tests on www.wwiiaircraftperformance.org it is showing similar climb times that is shown in the flight manual at combat setting, the big difference is during the flight test very aggressive Vx speeds were used. Again the climb times to 5000' in the flight manual are very similar to the flight tests, but using 20 gallons as a "one size fits all" does not really work although it is noted in the Flight Operation Instruction Sheet that "20 USG not available for flight." *That fuel got you to 5000' and in some cases that "20 gallons" could be as high as 26.8 depending on climb and weight.*

From 5000' to what ever altitude you intend to cruise at you have to chose a climb setting and speed (Vx or Vy) and *you are going to burn fuel getting there unless you have some Pixie Dust, Unicorn Poop, Groundhog mystical incantations!* *That has to be deducted once you get to your cruise altitude*. After that you can start allocating for higher power settings that will be used in combat (columns II to V of the Flight Operation Instruction Sheet). I don't think you can ever accurately predict what going to happen in combat so this is the most difficult thing to allocate for. In another thread Bill described a mission that his dad participated in and how the flight plan continually changed. So you get out a pencil (when you can) and start some in flight planning!








After this you can probably chose an economical altitude and speed to return home but note in our infamous Flight Operation Instruction Sheet it states clearly "NO RESERVE FUEL ALLOWANCE" so you're going to have to calculate at least 30 minutes (I would put 45 in there if I was flying over water returning to a land base).

Again - it was clearly pointed out by several others some of the errors in these flight manuals but it's funny how through-out this long and tedious ordeal GregP , ShortRound and I have come up with similar calculations. I would guess that our combined aviation experience is well over 100 years!!!!!

OK I'm done





GregP, ShortRound and myself paying respects

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## pbehn (Jul 22, 2021)

GregP said:


> Methinks you are cherry-picking again, trying desperately to use the absolute lightest P-39 you can find, with the highest internal fuel tankage you can find, and then use the *highest speed and climb numbers *you can find along with the longest range you can find.


I think those speed and climb numbers were obtained by using the same plane but with different props.

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## 33k in the air (Jul 22, 2021)

FLYBOYJ said:


> The comment on the Flight Operation Instruction Sheet about using 20 gallons for fuel for taxi, warm-up and climb to 5000' is actually wrong and should be removed as if conflicts with the climb data sheet on P 26.



I've seen other manuals for other aircraft make the same sort of understatement. It isn't limited to the P-39. I presume the lower value is just a rough figure used to ease the math for simple missions.


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## FLYBOYJ (Jul 22, 2021)

33k in the air said:


> I've seen other manuals for other aircraft make the same sort of understatement. It isn't limited to the P-39. I presume the lower value is just a rough figure used to ease the math for simple missions.


Exactly! But in the case of our iron bird could mean the difference of making it home or becoming part of the jungle.


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## FLYBOYJ (Jul 22, 2021)

33k in the air said:


> I've seen other manuals for other aircraft make the same sort of understatement. It isn't limited to the P-39. I presume the lower value is just a rough figure used to ease the math for simple missions.


Just looked in my P-38 manual, it allocates 60 gallons for this.


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## P-39 Expert (Jul 22, 2021)

Shortround6 said:


> The "expert" doesn't seem to grasp that the drop tank is immaterial.





Shortround6 said:


> Hang a 110 gallon tank on the P-39 and you might wind up in place you can't get home from.





Shortround6 said:


> You are down 10-15 gallons of internal fuel after warm up, take off and climb to safe height to switch tanks.





Shortround6 said:


> Now what is critical is how much fuel is remaining in the the internal tanks after 15-20 minutes of combat and allowing for a* 30 minute reserve*.
> 
> That is the fuel available for egress from the combat area.
> 
> ...





Shortround6 said:


> The "expert's" entire flight plan except for landing is based around continuous cruise in Column 1 conditions.


Okay, let's use your numbers. I don't agree with them but let's use them. 110gal internal when drop tank is jettisoned. Less your combat reserve 35gal and your 30 minute landing reserve 15gal leaves 60gallons to get home. Burning 62gph = .97hrs x 350mphTAS = 340mi. From the P-39N manual. 

Now if things get tight climb to 30000' and cruise at 305mphTAS burning 48gph. Same 60gal divided by 48gph = 1.25hr x 305mphTAS = 381mi. These are your numbers straight from the P-39N manual. 

And regarding cruising at 2600rpm (normal or max. continuous power) the engine chart says "UNLIMITED".


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## P-39 Expert (Jul 22, 2021)

GregP said:


> I checked my P-39N-0 and N-1 manual. It says 87 gallons internal, too. Then I checked my P-39K manual. It says 104 gallons internal + 16 gallons internal overload, for 120 gallons.
> 
> Let's see. They built 9,558 to 10,092 P-39 Airacobras. The P-39N accounted for 2,095 of them. The P-39Q accounted for 4,905 of them. That's 7,000 P-39s in the Q and N models alone, or 73% of them if you use the 9,558 build total.
> 
> ...


See Shortround's post #3079. If the AAF HAD decided to use the P-39 for escort work then they would have certainly used all available internal tankage. And probably 30gal fuel for the wing guns.


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## P-39 Expert (Jul 22, 2021)

Shortround6 said:


> A P-40F at 25,000ft had almost 10% more power when climbing than the P-39N and that is the P-40F running at 2850rpm and the P39N using 3000rpm.
> 
> Nobody was suggesting using the the P-40F as an escort fighter.
> 
> ...


Yes and a top speed of only 369.5mph and climb of only 2185fom at only 18000'. Escort was at 25000'+.


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## P-39 Expert (Jul 22, 2021)

pbehn said:


> It is specifically tested, without shackles, with shackles and with shackles and tank full (tank is 75gal type) 10MPH is a ball park figure but all figures are around that, and probably within experimental error. Tests at 13,000ft.
> 
> 
> 
> ...


This is for a 1941 P-39D loaded to 7800lbs. Escort would have been in 1943 with a P-39N.


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## 33k in the air (Jul 22, 2021)

FLYBOYJ said:


> Just looked in my P-38 manual, it allocates 60 gallons for this.



Yes, but what fuel consumption is given in the Climb, Take-Off, and Landing chart for a climb to the same altitude at that weight as to the allowance stated on the cruise/range charts? As I recall the allowance listed there is always less than what the climb chart shows.


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## pbehn (Jul 22, 2021)

P-39 Expert said:


> This is for a 1941 P-39D loaded to 7800lbs. Escort would have been in 1943 with a P-39N.


Did shackles stop creating drag around 1942? Your P-39 with full tanks and external shackles cruises at 25,000 ft just a few miles an hour slower than its absolute top speed and using only 62 g/hr. It is utter nonsense, as is the idea of climbing higher to save fuel.

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## Peter Gunn (Jul 22, 2021)

Pick any of the four (4) responses by 

 P-39 Expert
above and:

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## Glider (Jul 22, 2021)

Shortround6 said:


> The "D"s all had 120 gallons, the K & L & M all had 120 gallons.
> 
> The Q-1 had 87 gallons.
> The Q -5 had 110 gallons (?)
> ...


The attached may be of interest. It includes the long range of the Spit IX when fitted with internal extra tanks and the drop tanks. Its also noting at the bottom that these are still air figures but as a rule of thumb an average of 75% of the still air range is considered to be the operational range.

No one is pretending that the Spit was equal to the P51, the modified versions had quite a respectable range and the Tempest were pretty good. Both of these I believe comfortably exceed the P39.

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## FLYBOYJ (Jul 22, 2021)

33k in the air said:


> Yes, but what fuel consumption is given in the Climb, Take-Off, and Landing chart for a climb to the same altitude at that weight as to the allowance stated on the cruise/range charts? As I recall the allowance listed there is always less than what the climb chart shows.


On the climb chart for a P-38H Tank Supports Only "Allow 50 (60 for 2 165 gallon tanks) gallons for warm up, take off and an initial climb plus allowance for winds, reserve & combat as required."

The climb data chart starts fuel consumption at 10,000' Depending on weight and Vx/ Vy my manual shows between 60 and 70 gallons


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## P-39 Expert (Jul 22, 2021)

FLYBOYJ said:


> Some observations:
> 
> I've been going through the P-39N and Q manuals and been finding some "hokey" things in both (Imagine that). In the performance charts I can easily see how someone with little or no flight or aviation experience can be misled with some of the data, especially if you have conflicting information.
> 
> First, flight planning 101 - you use BOTH climb and cruise charts, end of story! The comment on the Flight Operation Instruction Sheet about using 20 gallons for fuel for taxi, warm-up and climb to 5000' is actually wrong and should be removed as if conflicts with the climb data sheet on P 26. Now if you look at the flight tests on www.wwiiaircraftperformance.org it is showing similar climb times that is shown in the flight manual at combat setting, the big difference is during the flight test very aggressive Vx speeds were used. Again the climb times to 5000' in the flight manual are very similar to the flight tests, but using 20 gallons as a "one size fits all" does not really work although it is noted in the Flight Operation Instruction Sheet that "20 USG not available for flight." *That fuel got you to 5000' and in some cases that "20 gallons" could be as high as 26.8 depending on climb and weight.*


The 20gal on the Flight Operations Instruction Chart is correct. It is an allowance. And it assumes climb to higher altitude starts at 5000' having traveled zero miles. This is being conservative since at least as soon as gear/flaps are up and climb speed is attained after form up the pilot will vector toward target. Then another 4.5min climbing to 5000' toward the target means an extra 13mi not included in calculations. 


FLYBOYJ said:


> From 5000' to what ever altitude you intend to cruise at you have to chose a climb setting and speed (Vx or Vy) and *you are going to burn fuel getting there unless you have some Pixie Dust, Unicorn Poop, Groundhog mystical incantations!* *That has to be deducted once you get to your cruise altitude*. After that you can start allocating for higher power settings that will be used in combat (columns II to V of the flight manual). I don't think you can ever accurately predict what going to happen in combat so this is the most difficult thing to allocate for. In another thread Bill described a mission that his dad participated in and how the flight plan continually changed. So you get out a pencil (when you can) and start some in flight planning!


Yes fuel will be burned climbing from 5000' to 25000' but 73mi range will be gained by climbing at 170mphIAS (220mphTAS average) for 20minutes in the direction of the target. One more time, this has all been factored into the range calculations for every altitude and every power setting. Take any amount of fuel available at any altitude at any power setting (RPM/manifold pressure) and do the math. Available fuel divided by gallons per hour x TAS is always more than the range figure quoted. The very smart AAF officers who put together these charts accounted for the fuel burned/miles gained by climbing from 5000' to whatever altitude is chosen. They did this to lessen pilot workload and get all the range information on one chart. You don't need the Takeoff, Climb and Landing Chart for any range calculations. 


FLYBOYJ said:


> View attachment 633243
> 
> 
> 
> After this you can probably chose an economical altitude and speed to return home but note in our infamous Flight Operation Instruction Sheet it states clearly "NO RESERVE FUEL ALLOWANCE" so you're going to have to calculate at least 30 minutes (I would put 45 in there if I was flying over water returning to a land base).


But I thought that previously you couldn't find any mention of any reserve for landing anywhere. Now we need 30minutes (you would use 45) to find our home field. That hasn't moved. I have always heard that the AAF used 20min. 


FLYBOYJ said:


> Again - it was clearly pointed out by several others some of the errors in these flight manuals but it's funny how through-out this long and tedious ordeal GregP , ShortRound and I have come up with similar calculations. I would guess that our combined aviation experience is well over 100 years!!!!!
> 
> OK I'm done


Or maybe you have been in your pixie dust, unicorn poop or mystical incantations again. I just use the appropriate flight manual.


FLYBOYJ said:


> View attachment 633242
> 
> GregP, ShortRound and myself paying respects

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## P-39 Expert (Jul 22, 2021)

FLYBOYJ said:


> On the climb chart for a P-38H Tank Supports Only "Allow 50 (60 for 2 165 gallon tanks) gallons for warm up, take off and an initial climb plus allowance for winds, reserve & combat as required."
> 
> The climb data chart starts fuel consumption at 10,000' Depending on weight and Vx/ Vy my manual shows between 60 and 70 gallons


Yes, the P-38 was a twin meaning that two engines must be started (separately) and two sets of propeller and mag checks must be undertaken (separately).


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## FLYBOYJ (Jul 22, 2021)

P-39 Expert said:


> The 20gal on the Flight Operations Instruction Chart is correct. It is an allowance. And it assumes climb to higher altitude starts at 5000' having traveled zero miles. This is being conservative since at least as soon as gear/flaps are up and climb speed is attained after form up the pilot will vector toward target. Then another 4.5min climbing to 5000' toward the target means an extra 13mi not included in calculations.


And it conflicts with part of the flight manual - Depending on how you fly its off by 6 gallons. This is about climb, not miles flown. Do you know what Vx and Vy is???


P-39 Expert said:


> Yes fuel will be burned climbing from 5000' to 25000' but 73mi range will be gained by climbing at 170mphIAS (220mphTAS average) for 20minutes in the direction of the target. One more time, this has all been factored into the range calculations for every altitude and every power setting. Take any amount of fuel available at any altitude at any power setting (RPM/manifold pressure) and do the math. Available fuel divided by gallons per hour x TAS is always more than the range figure quoted. The very smart AAF officers who put together these charts accounted for the fuel burned/miles gained by climbing from 5000' to whatever altitude is chosen. They did this to lessen pilot workload and get all the range information on one chart. You don't need the Takeoff, Climb and Landing Chart for any range calculations.


Again at what rate of climb?? What RPM??? VX or VY???? Those AAF offices were smart for the most part but got a lot wrong that has been clearly pointed out


P-39 Expert said:


> But I thought that previously you couldn't find any mention of any reserve for landing anywhere. Now we need 30minutes (you would use 45) to find our home field. That hasn't moved. I have always heard that the AAF used 20min.


You hear WRONG. 30 minutes is normal, 45 for IFR, the navy used 60. Did yo hear that from a gaming site?


P-39 Expert said:


> Or maybe you have been in your pixie dust, unicorn poop or mystical incantations again. I just use the appropriate flight manual.


I'm not the one who has made outrageous claims on here and been proven wrong by a host of people on this forum with years of aviation experience.

When are you going to do Bill's flight plan? When are you going to show us actually flight planning you have done? When are you going to show up your aviation resume? When are you going to answer poor Buffnut!

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## FLYBOYJ (Jul 22, 2021)

P-39 Expert said:


> Yes, the P-38 was a twin meaning that two engines must be started (separately) and two sets of propeller and mag checks must be undertaken (separately).


No kidding! I never knew that! How many mag checks have you done????


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## pbehn (Jul 22, 2021)

P-39 Expert said:


> Take any amount of fuel available at any altitude at any power setting (RPM/manifold pressure) and do the math.


Why dont you show us some math! On ram pressure, superchargers, compression and combustion, flame fronts mean effective pressure, propeller efficiency, lift drag. You could also try to explain how a plane becomes more economical as it gets closer to dropping out of the sky?

All you do is take numbers from a manual that are guidelines or wrong and multiply or divide them.

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## pbehn (Jul 22, 2021)

P-39 Expert said:


> Yes, the P-38 was a twin meaning that two engines must be started (separately) and two sets of propeller and mag checks must be undertaken (separately).


Thats worth 400 miles of fuel in a P-39. No wonder the P-38 wasnt produced much.

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## DerAdlerIstGelandet (Jul 22, 2021)

P-39 Expert said:


> You don't need the Takeoff, Climb and Landing Chart for any range calculations.





Now I am convinced we are being trolled.



P-39 Expert said:


> Or maybe you have been in your pixie dust, unicorn poop or mystical incantations again. I just use the appropriate flight manual.



Am I reading this right? Did you really just say this?

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## P-39 Expert (Jul 22, 2021)

FLYBOYJ said:


> And it conflicts with part of the flight manual - Depending on how you fly its off my 6 gallons. This is about climb, not miles flown. Do you know what Vx and Vy is???


No conflict, the 20gal is an allowance on the range chart. It ties into the rest of the numbers on the chart. The 26gal is a measurement on the takeoff, climb and landing chart. It has nothing to do with computing range. Everything you need for computing range is on the range chart. 


FLYBOYJ said:


> Again at what rate of climb?? What RMP??? VX or VY???? Those AAF offices were smart for the most part but got a lot wrong that has been clearly pointed out


I clearly pointed out that climb speed for the P-39N was 170mphIAS. The average altitude between 5000' and 25000' is 15000'. 170mphIAS at 15000' is 220mphTAS. I said all of that.


FLYBOYJ said:


> You hear WRONG. 30 minutes is normal, 45 for IFR, the navy used 60. Did yo hear that from a gaming site?


I was wrong? A few pages ago you had never heard of a landing reserve and couldn't find it quoted anywhere. I was the one that told you the USN used a 60min reserve to find an aircraft carrier maneuvering in the open ocean. Now you are the expert on landing reserve?


FLYBOYJ said:


> I'm not the one who has made outrageous claims on here and been proven wrong by a host of people on this forum with years of aviation experience.


There's a host if items that I have been proven correct. You have not proven me wrong on this range chart subject yet and I suspect that you won't.


FLYBOYJ said:


> When are you going to do Bill's flight plan? When are you going to show us actually flight planning you have done? When are you going to show up your aviation resume? When are you going to answer poor Buffnut!


I'm not a pilot but I have read the pilot manuals. If you have to be correct on every subject just because you are a pilot then the rest of us should just give up? Bill can compute his own crazy flight plan. I have computed numerous flight plans on here for the P-39 and the P-47 and the information comes straight from the manuals. Poor Buffnut. He's so concerned about the type of cabin heat on the P-39C when only 20 examples were completed and none saw combat. 20 examples. And I have explained on more than one occasion which models had the gas heater and which models had ducted air heat.


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## P-39 Expert (Jul 22, 2021)

pbehn said:


> Why dont you show us some math! On ram pressure, superchargers, compression and combustion, flame fronts mean effective pressure, propeller efficiency, lift drag. You could also try to explain how a plane becomes more economical as it gets closer to dropping out of the sky?
> 
> All you do is take numbers from a manual that are guidelines or wrong and multiply or divide them.


I have shown you the math on every single example. The available fuel, altitude, gallons per hour and IAS/TAS are straight from the manuals.


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## buffnut453 (Jul 22, 2021)

P-39 Expert said:


> Poor Buffnut. He's so concerned about the type of cabin heat on the P-39C when only 20 examples were completed and none saw combat. 20 examples. And I have explained on more than one occasion which models had the gas heater and which models had ducted air heat.



No you haven't explained. You keep stating that the export models had the gas heater while D variants onwards had ducted air. The number of P-39Cs produced is entirely irrelevant. It's simply a fact that it was a production airframe. I suspect that you keep equivocating on the topic because you clearly understand the thrust of my argument. You keep asserting that the dastardly Brits specified the unnecessary gas heater in a deliberate attempt to increase the weight of the P-400. The key flaw in this entire ridiculous argument is the timing of these events.

The British ordered the P-400 in late-1940. That was before the P-39C's first flight. Since the C variant also had the gas heater, it makes perfect sense that the same installation would be offered to the British as standard equipment for the type.

Furthermore, in order for the British to specify an extra and superfluous gas heater in late 1940 to deliberately make the P-400 overweight, it would mean they were attempting to sabotage the entire programme before any production P-39 variant had flown. Aside from requiring some real crystal ball gazing, why didn't they just not order the damn things and be done with it? Why go through the pain of deliberately ordering too much equipment on an aircraft that they'd already decided was useless before it was flown? That makes absolutely ZERO sense.

I really couldn't give two hoots about the various heaters in the P-39 variants. I do object when people trot out complete bullshit and refuse to acknowledge any evidence that contradicts it.

Looking forward to hearing how you try and dodge out of this latest information that flies in the face of your conspiracy theory.

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## pbehn (Jul 22, 2021)

P-39 Expert said:


> I have shown you the math on every single example. The available fuel, altitude, gallons per hour and IAS/TAS are straight from the manuals.


So you maintain that fuel economy increases with speed and altitude? Regardless of how many thousand feet you are above rated altitude and that the most economical altitude is where max speed, stall speed and cruise are the same? Have you any figures let alone a manual number for a P-39 at 30,000ft after dropping a 110gal tank at 25,000ft and climbing there? It is a fantasy nonsense scenario that defies physics, flight tests, everything I have ever read about flight and my whole life experience working with engines from mopeds through racing bikes to 5 litre V8s going across Saudi Arabia.

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## buffnut453 (Jul 22, 2021)

P-39 Expert said:


> P-39 Expert said:
> 
> 
> > I have shown you the math on every single example. The available fuel, altitude, gallons per hour and IAS/TAS are straight from the manuals.



Just because you can add numbers doesn't mean you're using the right equations. You have qualified, experienced pilots here telling you that your math is incorrect. You're just refusing to listen. I suggest you go back to flight sim or other fanboy forums 'cos your nonsense is getting really old.


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## GrauGeist (Jul 22, 2021)

P-39 Expert said:


> I'm not a pilot but I have read the pilot manuals


This is pure gold...

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## Thumpalumpacus (Jul 22, 2021)

GrauGeist said:


> This is pure gold...



"I'm not a doctor, but I play one on TV ..."

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## Thumpalumpacus (Jul 22, 2021)

FLYBOYJ said:


> When are you going to do Bill's flight plan? When are you going to show us actually flight planning you have done? When are you going to show up your aviation resume? When are you going to answer poor Buffnut!



As we say in the pool-halls down here: _quit talkin' and start chalkin'_.

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## P-39 Expert (Jul 22, 2021)

buffnut453 said:


> No you haven't explained. You keep stating that the export models had the gas heater while D variants onwards had ducted air. The number of P-39Cs produced is entirely irrelevant. It's simply a fact that it was a production airframe. I suspect that you keep equivocating on the topic because you clearly understand the thrust of my argument. You keep asserting that the dastardly Brits specified the unnecessary gas heater in a deliberate attempt to increase the weight of the P-400. The key flaw in this entire ridiculous argument is the timing of these events.
> 
> The British ordered the P-400 in late-1940. That was before the P-39C's first flight. Since the C variant also had the gas heater, it makes perfect sense that the same installation would be offered to the British as standard equipment for the type.
> 
> ...


Did the gas heater have weight? Yes. Was it necessary? No. Did the British order it on the P-400? Yes. Was it on any P-39 model not produced for export? No. Except the P-39C of which only 20 examples were produced. Gas heater on export models P-400, P-39D1 and P-39D2. No gas heater for domestic models P-39D/F/K/L/M/N/Q. Is this clear enough? Am I dodging your question in any way? This is about the 4th time I have explained this to you.


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## pbehn (Jul 22, 2021)

P-39 Expert said:


> Did the gas heater have weight? Yes. Was it necessary? No. Did the British order it on the P-400? Yes. Was it on any P-39 model not produced for export? No. Except the P-39C of which only 20 examples were produced. Gas heater on export models P-400, P-39D1 and P-39D2. No gas heater for domestic models P-39D/F/K/L/M/N/Q. Is this clear enough? Am I dodging your question in any way? This is about the 4th time I have explained this to you.


Bell told the British that this BS aeroplane had a ceiling of 36,000ft so it needs a heater for the pilot and the guns, as you have been told NAA put the same heater in the Mustang I without protest for the same reason. BTW the USA wasnt at war at the time, was it?

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## buffnut453 (Jul 22, 2021)

P-39 Expert said:


> Did the gas heater have weight? Yes. Was it necessary? No. Did the British order it on the P-400? Yes. Was it on any P-39 model not produced for export? No. Except the P-39C of which only 20 examples were produced. Gas heater on export models P-400, P-39D1 and P-39D2. No gas heater for domestic models P-39D/F/K/L/M/N/Q. Is this clear enough? Am I dodging your question in any way? This is about the 4th time I have explained this to you.



Why was the heater unnecessary? If the P-39C didn't have the ducted air heating then removing the gas heater means you're producing an aircraft without any form of cockpit heating. Even by 1941 standards, that would be poor. And that ignores the glaringly obvious fact that the USAAF and Bell both thought the gas heater was necessary for the P-39C.

Take a look at the timeline and please explain how and why the Brits would deliberately put too much weight into an aircraft that hadn't yet flown and then continue with the order? It would be much easier to just cancel the order before any metal was cut. They had the time to do exactly that...but they didn't. Why?

Stop your senseless criticism of the Brits which has ZERO basis in fact, in timeline, or in any records so far put forward. Indeed, the Brits accepted the P-400 AFTER a specially cleaned up airframe came within 1% of the minimum performance requirements. In other words, they still went ahead and paid Bell even though the P-400 FAILED TO MEET ITS PERFORMANCE SPECS.

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## buffnut453 (Jul 22, 2021)

pbehn said:


> Bell told the British that this BS aeroplane had a ceiling of 36,000ft so it needs a heater for the pilot and the guns, as you have been told NAA put the same heater in the Mustang I without protest for the same reason. BTW the USA wasnt at war at the time, was it?



I think your first point there is the crux of the matter. The Brits ordered the P-400 before any operational variant P-39 had flown. We have no idea what performance claims were made by Bell, although the chart provided earlier in this thread gives some indication that the pre-1941 performance estimates were ridiculously optimistic. Rather than the Brits deliberately besmirching the good name of Bell, it seems far more likely that Bell sold the Brits a bill of goods....and then failed to deliver on it.

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## pbehn (Jul 22, 2021)

buffnut453 said:


> I think your first point there is the crux of the matter. The Brits ordered the P-400 before any operational variant P-39 had flown. We have no idea what performance claims were made by Bell, although the chart provided earlier in this thread gives some indication that the pre-1941 performance estimates were ridiculously optimistic. Rather than the Brits deliberately besmirching the good name of Bell, it seems far more likely that Bell sold the Brits a bill of goods....and then failed to deliver on it.


Bell didnt do anything to tell the RAF that their estimates were way off. Supermarine almost lost the contract for Spitfires because of low levels of production between 1936 and 38, a part of this was the difficulty of producing wings, but within that as soon as the first models were tested the wings had to be changed to incorporate ducted heating. If the guns dont work the aeroplane is FFFing useless, a danger to its pilot and everyone that depends on it up to Churchill himself. I cant accept this being treated as a petty issue by the expert, it wasnt, and no requirement was placed on Bell that wasnt placed on everyone else. In fact I would go as far as saying gun heating on USA aircraft was something learned by the USA from British or others specifications, Bell were just behind the curve as usual.

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## Shortround6 (Jul 22, 2021)

I do like the way the P-39 "escorts" clear the airfield fence, get the gear up, switch to the drop tank and head for Germany.  

at some point in 1943 the P-47 groups changed number of aircraft per squadron to 25 aircraft. Or 75 planes for a 3 squadron group. even if not all planes are flying let's call it 50 planes operational on a given day. At 15 seconds between planes that is 12.5 minutes, at 20 seconds between planes that 16.7 minutes. 

Using the "experts" flight plan the lead plane/s are at about 15,000ft and 50 miles from the airfield when the last plane/s take off. 
This is actually brilliant planning as we don't have to worry about the fuel used in formation flying. There is NO formation. Just a bunch of planes in ones (mostly) and twos (occasionally) strung out over 50 miles winging their way into enemy airspace. 

I also like the way he picks which parts of the manuals (or which sentences ) he is going to use and which he is going to ignore.

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## FLYBOYJ (Jul 22, 2021)

P-39 Expert said:


> No conflict, the 20gal is an allowance on the range chart. It ties into the rest of the numbers on the chart. The 26gal is a measurement on the takeoff, climb and landing chart. It has nothing to do with computing range. Everything you need for computing range is on the range chart.


*YES IT IS A CONFLICT! 

And* *if you had any kind of aviation or flight training besides what you read while relaxing in your lounge chair you would recognize this! *

The only thing the climb chart and landing and take off charts have in common is they are printed on the same page, again, something that a novice wouldn't understand!


P-39 Expert said:


> I clearly pointed out that climb speed for the P-39N was 170mphIAS. The average altitude between 5000' and 25000' is 15000'. 170mphIAS at 15000' is 220mphTAS. I said all of that.


OK ... and???


P-39 Expert said:


> I was wrong? A few pages ago you had never heard of a landing reserve and couldn't find it quoted anywhere. I was the one that told you the USN used a 60min reserve to find an aircraft carrier maneuvering in the open ocean. *Now you are the expert on landing reserve?*


The reserve you are attempting to explain is an extended flight reserve just in case you get lost or have to deviate. It is there to make it to your destination. Again, your terminology as a novice further shows your lack of understanding. And yes *I AM AN EXPERT ON FLYING WITH A FUEL RESERVE! I'VE DONE IT! HAVE YOU????*


P-39 Expert said:


> There's a host if items that I have been proven correct. You have not proven me wrong on this range chart subject yet and I suspect that you won't.


I have but you're too much of a narcissist to admit when you're wrong, not only to me but to many other members on this forum!


P-39 Expert said:


> *I'm not a pilot *but I have read the pilot manuals.


We can definitely see that! I guess I can read manuals about brain surgery too!



P-39 Expert said:


> If you have to be correct on every subject just because you are a pilot then the rest of us should just give up?


*Rest of "us"?? No, but maybe YOU should!* * I think it's "YOU" vs. "the rest of us!"* There have been many well versed members on this forum who have proven me wrong many times (some of them "non-pilots") and when I see the evidence in front of me I take it as a learning experience, something that I've made a point to do when I first started in aviation over 40 years ago, but I think it's almost comical when you have 5 or 6 members coming up with the same conclusions who actually flown aircraft or worked in the industry attempting to show you the errors in your ways and you refuse to listen! But then again, *you're NOT a pilot but read the manuals! *



P-39 Expert said:


> Bill can compute his own crazy flight plan. I have computed numerous flight plans on here for the P-39 and the P-47 and the information comes straight from the manuals.


And probably half of what you're computed is in error because despite "reading the manuals" you don't have the training or background to fully grasp what you're looking at!


P-39 Expert said:


> Poor Buffnut. He's so concerned about the type of cabin heat on the P-39C when only 20 examples were completed and none saw combat. 20 examples. And I have explained on more than one occasion which models had the gas heater and which models had ducted air heat.


First time I'm hearing it!






*"I'm not a pilot but I have read the pilot manuals."*


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## FLYBOYJ (Jul 22, 2021)

Shortround6 said:


> I also like the way he picks which parts of the manuals (or which sentences ) he is going to use and which he is going to ignore.


But remember - *He's not a pilot but have read the pilot manuals.*


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## tyrodtom (Jul 22, 2021)

A lot of humor in this thread.
I think I got my biggest laugh when P-39 expert ask for the definition of a troll.

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## GrauGeist (Jul 22, 2021)

tyrodtom said:


> A lot of humor in this thread.
> I think I got my biggest laugh when P-39 expert ask for the definition of a troll.


I *almost* said "have a look in the mirror", but held back.

Well...now it's out there, isn't it?

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## 33k in the air (Jul 23, 2021)

If only it had been accepted at the time, the war surely would have been shortened.

"P-39, Cadillac of the skies!" is what Jim should have been yelling in _Empire of the Sun_.

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## DerAdlerIstGelandet (Jul 23, 2021)

Shortround6 said:


> I do like the way the P-39 "escorts" clear the airfield fence, get the gear up, switch to the drop tank and head for Germany.
> 
> at some point in 1943 the P-47 groups changed number of aircraft per squadron to 25 aircraft. Or 75 planes for a 3 squadron group. even if not all planes are flying let's call it 50 planes operational on a given day. At 15 seconds between planes that is 12.5 minutes, at 20 seconds between planes that 16.7 minutes.
> 
> ...



Post of the day.

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## GregP (Jul 23, 2021)

Sorry I missed the 120-gal models, but the manuals (early models of each letter) I have do not state 120 or 110 gallons. Since I'm not a great P-39 fan, I only have about five or six P-39 manuals, and depended upon them for data.

Mea culpa!

OK, use 110 - 120 gal internal. Gets you another half hour of running or so. Add 15 minutes in each direction.

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## GrauGeist (Jul 23, 2021)

Well, for God sakes, why all this fiddling around?
Stuff a 330 gallon drop tank on that Cobra - according to the authority, the more fuel it has, the faster and higher it can fly.
All that work and money spent on the A-12 Archangel when the obvious solution was right there the whole time...

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## buffnut453 (Jul 23, 2021)

FLYBOYJ said:


> *He's not a pilot but have read the pilot manuals.*



I can read a treatise on quantum physics but that doesn't mean I understand it. 

This seems to be a "dog watching tennis" situation. The dog likes to watch the yellow ball going back and forth but he has no idea of why it's happening or the rules of the game.

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## ThomasP (Jul 23, 2021)

I do not know if the following has been posted in this thread before, but for what it is worth:











Have fun.

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## pbehn (Jul 23, 2021)

Shortround6 said:


> I do like the way the P-39 "escorts" clear the airfield fence, get the gear up, switch to the drop tank and head for Germany.
> 
> at some point in 1943 the P-47 groups changed number of aircraft per squadron to 25 aircraft. Or 75 planes for a 3 squadron group. even if not all planes are flying let's call it 50 planes operational on a given day. At 15 seconds between planes that is 12.5 minutes, at 20 seconds between planes that 16.7 minutes.


Why not paint them bright colours with bands, stripes and circles any bomber box wandering aimlessly in the North Sea could form up and act as top cover.

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## Peter Gunn (Jul 23, 2021)

P-39 Expert said:


> Yes, the P-38 was a twin meaning that two engines must be started (separately) and two sets of propeller and mag checks must be undertaken (separately).


What the barreling f**K?!?! The P-38 has TWO engines? Why didn't anybody tell me this earlier?

All these years you all knew this and didn't let me in on it... *Sniffle* and here I thought we were friends...

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## Peter Gunn (Jul 23, 2021)

P-39 Expert said:


> *SNIP*
> 
> Bill can compute his own crazy flight plan. I have computed numerous flight plans on here for the P-39 and the P-47 and the information comes straight from the manuals. *SNIP*


Yeaaah, see here's the thing, Bill can, probably off the top of his head, give you a rough estimate for a mission profile and be more accurate than someone reading a pilots manual and running figures for hours. If he actually devoted time to it, you could bet the house it'd be correct.

I've read pilots manuals too, the first time I did a mission profile for a Mustang it didn't come near what the AAF planners accomplished because they were, well, you know, dare I say "Experts"?

Once I started flying the scales fell from my eyes so to speak. Granted, I haven't touched an airplane since 1981 or so, so my knowledge like most of my sanity is out the window, but my opinion is you should listen to the people here that are actually in aviation.

BTW, I don't think Bill is capable of computing a "crazy" flight plan, unless it involves distilled brown liquid and burned cow.

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## Shortround6 (Jul 23, 2021)

buffnut453 said:


> I think your first point there is the crux of the matter. The Brits ordered the P-400 before any operational variant P-39 had flown. We have no idea what performance claims were made by Bell, although the chart provided earlier in this thread gives some indication that the pre-1941 performance estimates were ridiculously optimistic. Rather than the Brits deliberately besmirching the good name of Bell, it seems far more likely that Bell sold the Brits a bill of goods....and then failed to deliver on it.


The big failing in the British "conspiracy theory" is that the British didn't order the P-400 in the First place. 
*The French did* and Britain took over the order when France fell. Britain also took over just about ALL French orders for defense goods when France fell. 
Major revisions to the French specification in the summer of 1940 was pretty much to get the plane flyable to British standards, like change the direction of throttle operation, substitute non metric instruments, make sure British and American guns could be used and not French supplied guns, shelves/brackets for British radios and so on. 
This was done BEFORE the Americans ordered any P-39Ds or changed the last of the P-39Cs to Ds. It kind of locks the British into a certain configuration. 

The "expert" seems to think you can just change things at a whim. It may take dozens of drawings to made to change the heating system. You need drawings of even such things as a knob and control cable to open a door in a duct. Let alone drawings of the duct. The more changes you make the longer it takes to get your finished airplanes. 

There were two more specification revisions, one several months before Lend lease was passed and one several months after. 

Bell had several opportunities to revise the performance specifications, they didn't. 

Were the British even offered the new heating system? 

Unless there are documents showing the British turned down the new heating system and keeping the gas fired heaters then this portion of the debate should be put to rest.

Coincidence is not proof.

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## FLYBOYJ (Jul 23, 2021)

ThomasP said:


> I do not know if the following has been posted in this thread before, but for what it is worth:
> 
> View attachment 633283
> 
> ...


Never been posted but the same instructions are indicated on the Flight Operation Instruction *Charts *and I bolded *"CHARTS" *to indicate more than one. The instructions are quite clear but mentions nothing about fuel consumed during climbs, so I guess we have to omit that consideration! Thanks for posting!


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## FLYBOYJ (Jul 23, 2021)

DerAdlerIstGelandet said:


> Post of the day.


Comment of the year;

"I'm not a pilot but I have read the pilot manuals."

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## SaparotRob (Jul 23, 2021)

Does anyone remember what this thread was originally about? What was being discussed about the P-39 that the thread was to answer?


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## GrauGeist (Jul 23, 2021)

SaparotRob said:


> Does anyone remember what this thread was originally about? What was being discussed about the P-39 that the thread was to answer?


It was something about the 1949 Studebaker's goofy back window.

I think...

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## SaparotRob (Jul 23, 2021)

I think you're right!


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## buffnut453 (Jul 23, 2021)

Shortround6 said:


> The big failing in the British "conspiracy theory" is that the British didn't order the P-400 in the First place.
> *The French did* and Britain took over the order when France fell. Britain also took over just about ALL French orders for defense goods when France fell.
> Major revisions to the French specification in the summer of 1940 was pretty much to get the plane flyable to British standards, like change the direction of throttle operation, substitute non metric instruments, make sure British and American guns could be used and not French supplied guns, shelves/brackets for British radios and so on.
> This was done BEFORE the Americans ordered any P-39Ds or changed the last of the P-39Cs to Ds. It kind of locks the British into a certain configuration.
> ...



Agree with all. What's even more infuriating is the continual statement that the British specified the gas heater. They'd have done no such thing. They probably would have specified that the cockpit should be heated but the specifics of how would be left to the aircraft manufacturer. 

The whole theory that the Brits deliberately added a gas heater to help increase the P-400's weight so they could get out of the contract is so ridiculous. Anyone who's worked in procurement, or any person with a ha'pen'orth of common sense who looks at the timeline of actual events, would recognize that it's nonsense...and yet here we are with the same conspiracy theory still being trotted out.

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## pbehn (Jul 23, 2021)

Shortround6 said:


> The big failing in the British "conspiracy theory" is that the British didn't order the P-400 in the First place.
> *The French did* and Britain took over the order when France fell. Britain also took over just about ALL French orders for defense goods when France fell.
> Major revisions to the French specification in the summer of 1940 was pretty much to get the plane flyable to British standards, like change the direction of throttle operation, substitute non metric instruments, make sure British and American guns could be used and not French supplied guns, shelves/brackets for British radios and so on.
> This was done BEFORE the Americans ordered any P-39Ds or changed the last of the P-39Cs to Ds. It kind of locks the British into a certain configuration.
> ...


I have asked for this several times before, there is a massive difference between specifying that the cabin and guns should be heated, and accepting a manufacturers proposal to do the same, to "saying use this heater in your plane". The Hurricane and Spitfire used ducted air systems, why would the British reject one?

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## special ed (Jul 23, 2021)

"Expert" reminds me of the German entry in the movie "The magnificent men in their flying machines." In case no one saw or remembers, "There is nothing a German officer can't do. All he needs is the manual."

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## GrauGeist (Jul 23, 2021)

Waiting for the point where the British are blamed for the engine being mounted mid-ship.
Because it's obvious that the Bell product would have been far superior with the engine mounted in the nose (without nose armor, of course).

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## SaparotRob (Jul 23, 2021)

That whole line of reason is ridiculous. Britain was at war. I’m sure Britain wanted competent aircraft, not legal gyrations to get out of a contract it didn’t sign. They “inherited“ these planes from the French. If the P-39 or P-400 worked the RAF would have been delighted.

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## FLYBOYJ (Jul 23, 2021)

buffnut453 said:


> The whole theory that the Brits deliberately added a gas heater to help increase the P-400's weight so they could get out of the contract is so ridiculous. Anyone who's worked in procurement, or any person with a ha'pen'orth of common sense who looks at the timeline of actual events, would recognize that it's nonsense...and yet here we are with the same conspiracy theory still being trotted out.


And it was well documented that Lockheed had conflict with the British over the castrated P-38s, Lockheed took the issue to legal arbitration, if this was remotely true I'm sure Bell "could have" taken the same path.

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## GregP (Jul 23, 2021)

I am reminded of a classic quote, "When you're up to your ass in alligators, its tough to remember that your initial objective was to drain the swamp."

I'm trying to remember that it ain't the P-39's fault that we've been through this ordeal.

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## SaparotRob (Jul 23, 2021)

It really is a beautiful airplane. Too bad it wasn’t better. As I learned from this thread, there was no room in the airframe for improvements.

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## buffnut453 (Jul 23, 2021)

I actually like the P-39...have done ever since I was a wee one and saw an article by Ray Rimell about building the Monogram 1/48 kit. I just HAD to get hold of that kit. It was so cool, with the ability to leave panels off to display the engine and gun bay, and leave the cockpit door open. 

That said, there are a great many aircraft that I really, REALLY like but which weren't great performers: Buffalo, Skua, Whirlwind, Vildebeest, Wellesley, Lysander, A-17, Defiant, Blenheim, P-66, P-35, P-36, Fokker D-XXI, CW-21 etc etc. I'm just objective about their relative strengths and weaknesses. For me, the more interesting part is the courage of the crews who flew them.

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## SaparotRob (Jul 23, 2021)

Just as an aside, could there have been an engine, post war, that could have been mounted in the P-39 airframe that would give it claimed performance? Not talking Reno Racers. 
I was even thinking of the jet engine that the Bee-Dee 5 had.


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## FLYBOYJ (Jul 23, 2021)

buffnut453 said:


> I actually like the P-39...have done ever since I was a wee one and saw an article by Ray Rimell about building the Monogram 1/48 kit. I just HAD to get hold of that kit. It was so cool, with the ability to leave panels off to display the engine and gun bay, and leave the cockpit door open.
> 
> That said, there are a great many aircraft that I really, REALLY like but which weren't great performers: Buffalo, Skua, Whirlwind, Vildebeest, Wellesley, Lysander, A-17, Defiant, Blenheim, P-66, P-35, P-36, Fokker D-XXI, CW-21 etc etc. I'm just objective about their relative strengths and weaknesses. For me, the more interesting part is the courage of the crews who flew them.


Same feelings - always thought it was a great looking airplane despite it's limitations. I will say I've learned a lot about this aircraft during these discussions, even our "Expert" brought up things I didn't know about production configurations and aircraft assembly.

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## FLYBOYJ (Jul 23, 2021)

special ed said:


> "Expert" reminds me of the German entry in the movie "The magnificent men in their flying machines." In case no one saw or remembers, "There is nothing a German officer can't do. *All he needs is the manual."*


I find this to be the most dangerous thing when you find folks with limited or no flight training reading flight manuals and trying to interpret items that require introductory training to fully understand. Maintenance and assembly manuals are easier unless you're doing things like weight and balance, magneto timing, or computing bend allowance or rivet spacing during repairs. It has to be noted that some of these WW2 flight manuals lack some information, have typo errors and even have aircraft specific information omitted.

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## buffnut453 (Jul 23, 2021)

FLYBOYJ said:


> Same feelings - always thought it was a great looking airplane despite it's limitations. I will say I've learned a lot about this aircraft during these discussions, even our "Expert" brought up things I didn't know about production configurations and aircraft assembly.



Agree, although I learned more from the likes of SR6 and others who actually provided data to back up their claims. I have learned a lot more about the P-39, though. The most striking thing for me was the sheer number of variants for a relatively modest production run, and how frequently fuel and armour requirements seemed to flip-flop between variants.

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## pbehn (Jul 23, 2021)

I learned a lot about heaters.

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## pbehn (Jul 23, 2021)

SaparotRob said:


> Just as an aside, could there have been an engine, post war, that could have been mounted in the P-39 airframe that would give it claimed performance? Not talking Reno Racers.
> I was even thinking of the jet engine that the Bee-Dee 5 had.


Well the Kingcobra did late in the war, if the P-39 was designed around a two stage Merlin it would have done what was claimed, but that was its problem. The P-51A/ Mustang MkII did what was claimed but werent called the P-410.

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## buffnut453 (Jul 23, 2021)

pbehn said:


> I learned a lot about heaters.



Me too! Glad to be of assistance.

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## swampyankee (Jul 23, 2021)

FLYBOYJ said:


> I find this to be the most dangerous thing when you find folks with limited or no flight training reading flight manuals and trying to interpret items that require introductory training to fully understand. Maintenance and assembly manuals are easier unless you're doing things like weight and balance, magneto timing, or computing bend allowance or rivet spacing during repairs. It has to be noted that some of these WW2 flight manuals lack some information and even have aircraft specific information omitted.


I loved the duel over the septic pond.

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## 33k in the air (Jul 23, 2021)

FLYBOYJ said:


> Comment of the year;
> 
> "I'm not a pilot but I have read the pilot manuals."



But he did stay at a Holiday Inn Express last night.

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## FLYBOYJ (Jul 23, 2021)

33k in the air said:


> But he did stay at a Holiday Inn Express last night.


If I could I would give you bacon as well!

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## pbehn (Jul 23, 2021)

FLYBOYJ said:


> I find this to be the most dangerous thing when you find folks with limited or no flight training reading flight manuals and trying to interpret items that require introductory training to fully understand. Maintenance and assembly manuals are easier unless you're doing things like weight and balance, magneto timing, or computing bend allowance or rivet spacing during repairs. It has to be noted that some of these WW2 flight manuals lack some information, have typo errors and even have aircraft specific information omitted.


I found the whole wording of the manual very odd, it is written as if speaking to a P-39 owner, not a trainee pilot or a pilot in a military force. Every pilot who is actually approved to fly the thing will have had to pass tests in all the basic theory that it states. 

Then the conspiracy theorist in me gets to work and I wonder if mistakes and anomalies in the manual were put there to make trainee pilots really think about what they were doing.

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## Thumpalumpacus (Jul 23, 2021)

P-39 Expert said:


> [...] If you have to be correct on every subject just because you are a pilot then the rest of us should just give up? Bill can compute his own crazy flight plan. I have computed numerous flight plans on here for the P-39 and the P-47 and the information comes straight from the manuals.



I think the difference is that when real pilots here produce real flight plans and said real flight plan doesn't work, their ass is in the plane's seat and not a computer-desk chair.



SaparotRob said:


> It really is a beautiful airplane. Too bad it wasn’t better. As I learned from this thread, there was no room in the airframe for improvements.



I had no idea exactly how cramped that airframe was before reading this thread. Only after learning that did I see how the engine's placement was precisely the factor that prevented it from being suitable to modifications to extend its usefulness.

Soviet (and to a lesser extent, American) pilots made good use of the airplane -- but that was in spite of its flaws, not because of its superiorities.

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## FLYBOYJ (Jul 23, 2021)

pbehn said:


> I found the whole wording of the manual very odd, it is written as if speaking to a P-39 owner, not a trainee pilot or a pilot in a military force. Every pilot who is actually approved to fly the thing will have had to pass tests in all the basic theory that it states.
> 
> *Then the conspiracy theorist in me gets to work and I wonder if mistakes and anomalies in the manual were put there to make trainee pilots really think about what they were doing.*


To a point!

I have found that many WW2 manuals are written in this manner, perhaps to accommodate those who had zero aviation experience when they first enlisted or were drafted. After WW2 the whole format changed (and as you probably know) were given a document number followed by a -1, so in today's world the flight manuals is known as the "dash one" (-1). 

When I was training to fly the L29 we used a flight manual from the Nigerian AF that was written in -1 format. It made things pretty simple when compared to the original Czech manuals, obviously the translation was much better

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## Clayton Magnet (Jul 23, 2021)

Years ago, we had a couple Hawker Hunters visit the hanger, which were being used as adversarial trainers for the RCAF. The aircraft were ex-Swiss airforce, and being operated by a Quebec based company (now defunct). So the manuals were originally in English, translated to Swiss, then changed to French. They were an absolute mess

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## FLYBOYJ (Jul 23, 2021)

Clayton Magnet said:


> Years ago, we had a couple Hawker Hunters visit the hanger, which were being used as adversarial trainers for the RCAF. The aircraft were ex-Swiss airforce, and now being operated by a Quebec based company (now defect). So the manuals were originally in English, translated to Swiss, then changed to French. They were an absolute mess


Swiss = French, German or Italian from what I understand


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## Marcel (Jul 23, 2021)

But I am a bit tired of the way this 'discussion' is going on and on and on. It's a bit like the herd against the individual. One has to admire the stubborness of mr. Expert. If anyone would reacted to me the way you guys do to him, I would have quit long ago. I must admit he's asking a bit for it by relentlesly returning to this topic with his own ideas while he knows he will not convert anyone to his point of view and will only get flak for doing so. One is wondering what the purpose of that is, seems to me like a waste of time. I'm also wondering why you guys keep on reacting. Don't you get tired of that? You know that ignoring a thread is well doable? I stay at my optinion, that here on the forum, there is some tendensy to masochism. Everybody in this thread seems keen to be annoyed.

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## pbehn (Jul 23, 2021)

Clayton Magnet said:


> Years ago, we had a couple Hawker Hunters visit the hanger, which were being used as adversarial trainers for the RCAF. The aircraft were ex-Swiss airforce, and being operated by a Quebec based company (now defunct). So the manuals were originally in English, translated to Swiss, then changed to French. They were an absolute mess


When I worked on a pipeline in Russia, the specification was the American API 5L. The Russians obviously translated it to Russian for their use. When BP became involved and had UK inspectors on site, instead of giving us the APL 5L spec. they gave us an incomprehensible translation of the Russian spec. back to English. Meetings with the Russian management were "fun".

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## 33k in the air (Jul 23, 2021)

FLYBOYJ said:


> If I could I would give you bacon as well!



As long as it's not Bell brand bacon. I hear it doesn't live up to its reputation.

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## Thumpalumpacus (Jul 23, 2021)

Marcel said:


> But I am a bit tired of the way this 'discussion' is going on and on and on. It's a bit like the herd against the individual. One has to admire the stubborness of mr. Expert. If anyone would reacted to me the way you guys do to him, I would have quit long ago. I must admit he's asking a bit for it by relentlesly returning to this topic with his own ideas while he knows he will not convert anyone to his point of view and will only get flak for doing so. One is wondering what the purpose of that is, seems to me like a waste of time. I'm also wondering why you guys keep on reacting. Don't you get tired of that? You know that ignoring a thread is well doable? I stay at my optinion, that here on the forum, there is some tendensy to masochism. Everybody in this thread seems keen to be annoyed.



I visit this thread because I learn more about the airplane and flight in general, both from 

 P-39 Expert
's posts, and the replies those posts generate.

If this thread is a tennis-match of back-and-forth, I'm a spectator, simply enjoying the match.

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## GrauGeist (Jul 23, 2021)

Marcel said:


> But I am a bit tired of the way this 'discussion' is going on and on and on. It's a bit like the herd against the individual. One has to admire the stubborness of mr. Expert. If anyone would reacted to me the way you guys do to him, I would have quit long ago. I must admit he's asking a bit for it by relentlesly returning to this topic with his own ideas while he knows he will not convert anyone to his point of view and will only get flak for doing so. One is wondering what the purpose of that is, seems to me like a waste of time. I'm also wondering why you guys keep on reacting. Don't you get tired of that? You know that ignoring a thread is well doable? I stay at my optinion, that here on the forum, there is some tendensy to masochism. Everybody in this thread seems keen to be annoyed.


On the otherhand, this forum strives for accuracy and when an individual tries to propagate blatant falsehoods, the outcome is inevitable.

There's been plenty of exchanges similar to this over the years, although they didn't seem to last as long because the preponderance of fact outweighed the falsehoods.

The one consolation of this protracted thread, is that a newcomer will come away with a substantial amount of information about the P-39 (and variants) and will most certainly be able to spot misinformation if/when posted elsewhere on the web.

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## Marcel (Jul 23, 2021)

GrauGeist
true, but only if they have the stammina to plough through all these posts. I don't see any purpose anymore, but don't worry, I'm not going to close the thread.

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## FLYBOYJ (Jul 23, 2021)

Marcel said:


> But I am a bit tired of the way this 'discussion' is going on and on and on. It's a bit like the herd against the individual. One has to admire the stubborness of mr. Expert. If anyone would reacted to me the way you guys do to him, I would have quit long ago. I must admit he's asking a bit for it by relentlesly returning to this topic with his own ideas while he knows he will not convert anyone to his point of view and will only get flak for doing so. One is wondering what the purpose of that is, seems to me like a waste of time. I'm also wondering why you guys keep on reacting. Don't you get tired of that? You know that ignoring a thread is well doable? I stay at my optinion, that here on the forum, there is some tendensy to masochism. Everybody in this thread seems keen to be annoyed.


Marcel, I agree for the most part but what bothers me is when some of us (to include myself) try to educate this individual and we are met with a narcissistic response, most disturbing when several of us have worked in this industry for many years and have hands on knowledge of some of these topics. It isn't a matter of masochism, it's a matter of an individual putting out blatantly wrong information

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## buffnut453 (Jul 23, 2021)

Marcel said:


> GrauGeist
> true, but only if they have the stammina to plough through all these posts. I don't see any purpose anymore, but don't worry, I'm not going to close the thread.



If you did, it'd be a fair bet that another "P-39 is a forgotten war-winner" thread would open very shortly thereafter....or we'd end up with another series of P-39 comments spamming other threads.

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## FLYBOYJ (Jul 23, 2021)

GrauGeist said:


> this forum strives for accuracy and when an individual tries to propagate blatant falsehoods, the outcome is inevitable.


Amen

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## Marcel (Jul 23, 2021)

FLYBOYJ said:


> Marcel, I agree for the most part but what bothers me is when some of us (to include myself) try to educate this individual and we are met with a narcissistic response, most disturbing when several of us have worked in this industry for many years and have hands on knowledge of some of these topics. It isn't a matter of masochism, it's a matter of an individual putting out blatantly wrong information


Yeah agree, but if you're not getting through, at what point is it enough? Or will everybody keep running circles forever? BTW, very glad you are in this thread, because I could not stand moderating this.


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## Marcel (Jul 23, 2021)

buffnut453 said:


> If you did, it'd be a fair bet that another "P-39 is a forgotten war-winner" thread would open very shortly thereafter....or we'd end up with another series of P-39 comments spamming other threads.


Very true.


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## Clayton Magnet (Jul 23, 2021)

My take from this thread so far, which I do find quite enjoyable, can be summed up as "...*IF ONLY* Bell had built the aircraft with _these_ modifications, and used _this_ engine instead, and _ignored_ British meddling, and perhaps most importantly, delivered this masterpiece a _year or two_ earlier, it would have been a war-winner..." All the while taking liberties with the flight manual numbers, to stretch out the perceived performance.
If nothing else, its interesting from a "what-if" scenario

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## Marcel (Jul 23, 2021)

Clayton Magnet said:


> My take from this thread so far, which I do find quite enjoyable, can be summed up as "...*IF ONLY* Bell had built the aircraft with _these_ modifications, and used _this_ engine instead, and _ignored_ British meddling, and perhaps most importantly, delivered this masterpiece a _year or two_ earlier, it would have been a war-winner..." All the while taking liberties with the flight manual numbers, to stretch out the perceived performance.
> If nothing else, its interesting from a "what-if" scenario


Then we should move it to the special 'what if' section. Hmmm, that's an idea....

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## FLYBOYJ (Jul 23, 2021)

Marcel said:


> Yeah agree, but if you're not getting through, at what point is it enough? Or will everybody keep running circles forever?


Thus the reason for this thread.

Personally I have stepped back several times and let the banter fly but after a while jumped into the fray when I see incredibly wrong and inaccurate things said. Again as GrauGeist put it "this forum strives for accuracy and when an individual tries to propagate blatant falsehoods, the outcome is inevitable." I think we have strived to ensure that honest and accurate information has been discussed here and challenge those who do otherwise, for what ever reason


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## Marcel (Jul 23, 2021)

Okay, fair enough. I do hope that this all can be done with respect on both sides, though.

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## Shortround6 (Jul 23, 2021)

I am not sure why all the fuss about the heater.

A similar device was used in thousands if not tens of thousands of Beechcraft, Cessna, Piper and other private/small business/air taxi aircraft.

A 20,000BTU unit for a Cessna 310 went 20.5 lbs. It was made by a subsidiary of the original company that made the heaters for the P-400s and all. 

If 20-30lbs was make or break for the P-39 then It had other problems. 

Some of our members who are pilots or worked on aircraft may be familiar with this type of heater.

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## FLYBOYJ (Jul 23, 2021)

Shortround6 said:


> I am not sure why all the fuss about the heater.
> 
> A similar device was used in thousands if not tens of thousands of Beechcraft, Cessna, Piper and other private/small business/air taxi aircraft.
> 
> ...

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## SaparotRob (Jul 23, 2021)

FLYBOYJ said:


> Marcel, I agree for the most part but what bothers me is when some of us (to include myself) try to educate this individual...


You guys have educated a bunch of individuals, though. The more an error has tried to have been explained, the better my understanding of why its wrong becomes. I was the slow kid in class.

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## SaparotRob (Jul 23, 2021)

Yet another epiphany. I now have a vague idea of what NOT to do when considering an aircraft design.

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## Clayton Magnet (Jul 23, 2021)

FLYBOYJ said:


> View attachment 633300


Hate those Janitrols!

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## XBe02Drvr (Jul 23, 2021)

Shortround6 said:


> Some of our members who are pilots or worked on aircraft may be familiar with this type of heater.


Roger that! Concur. Nearly froze to death when one crapped out 10,000 feet over northern Maine one winters night with an OAT < -20° F. Why the Be99 relied on a Janitrol when all that bleed air was available is beyond me.

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## pbehn (Jul 23, 2021)

Shortround6 said:


> I am not sure why all the fuss about the heater.
> 
> A similar device was used in thousands if not tens of thousands of Beechcraft, Cessna, Piper and other private/small business/air taxi aircraft.
> 
> ...


I agree that 20Lbs of weight isnt anything to make a fuss over, the heater certainly was though. Most fighters had the engine in front of the pilot, so a lot of heat came backwards from the engine and also many hot pipes for gun heaters, water and oil radiators went around the cockpit. How the guns and pilot were kept hot enough to work is a completely legitimate question to be asked. ( I know you know, it seems a mystery to others).






hawker hurricane engine bulkhead - Bing


Find high-quality images, photos, and animated GIFS with Bing Images




www.bing.com

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## XBe02Drvr (Jul 23, 2021)

Jees, only forty more pages to the big two double oh! Think we can make it?


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## XBe02Drvr (Jul 23, 2021)

special ed said:


> "There is nothing a German officer can't do. All he needs is the manual."





FLYBOYJ said:


> I find this to be the most dangerous thing when you find folks with limited or no flight training reading flight manuals and trying to interpret items that require introductory training to fully understand.





Thumpalumpacus said:


> I think the difference is that when real pilots here produce real flight plans and said real flight plan doesn't work, their ass is in the plane's seat and not a computer-desk chair.


No Airplane Flight Manual is meant to be a "Piloting for Dummies" course on learning to fly. It assumes a level of airmanship appropriate to the airplane in question, something the untrained "armchair pilot" is woefully unprepared for. What said imaginary aviator lacks is the context to functionally interpret the information presented. He doesn't know how much he doesn't know and thinks he knows all he needs to know.
In my flight instructing days I encountered the occasional such individual, and after a couple of attempts to salvage their dreams, I would send them packing. People like that are a danger to everyone who shares an airplane or even shares a sky with them.
The thing that gets me is that our X-spurt friend calculates everything to the last second of time and the last drop of fuel in a desperate attempt to make a marginal plane into a viable performer, no provision for the fudge factors that abound in an operation as complex as an escorted bombing raid. What if the bombers are 20 minutes late to the rendezvous? What if the Abbeville boys force you to drop tanks as you go "feet dry" on the French coast? What if all southern England is "socked in" on your return? Gotta have plan bravo, and plan charlie, and plan delta, and an airplane that has the capacity to handle those contingencies. Which is NOT the P39.

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## Snautzer01 (Jul 23, 2021)

XBe02Drvr said:


> Jees, only forty more pages to the big two double oh! Think we can make it?


Does loosing the nose armour shift Cog?


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## buffnut453 (Jul 23, 2021)

Snautzer01 said:


> Does loosing the nose armour shift Cog?



Stop that! Stop that!!! We'll have none o' that here!!!!




"Folk said I was daft to remove the nose armour from my P-39...but I did it anyway."

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## Snautzer01 (Jul 23, 2021)

I agree, i rather sing. But there you have it. Tell me this What is the airspeed velocity of an unladen P-39 ? The European one. Not the African one.

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## FLYBOYJ (Jul 23, 2021)

XBe02Drvr said:


> In my flight instructing days I encountered the occasional such individual, and after a couple of attempts to salvage their dreams, I would send them packing. People like that are a danger to everyone who shares an airplane or even shares a sky with them.


100% Wes!

Maybe that's why I have gotten irritated a few times over this. As a young kid I would love to get my hands on a flight manual and just drool all over it in hopes of becoming an expert on said airplane. There were many terms and references in these manuals that I glossed over and it wasn't until years later when I first took ground school how some of this data came together in my brain. I'm sure I would have held the same "I'm not a pilot but read the manual" attitude had I had similar discussions with my peers back then.

V speeds, density altitude, basic weight and balance, engine performance charts are some things most people will not firmly grasp by reading flight manuals for high performance aircraft, be that from WW2 or today without some kind of basic education on said subject matter. It's been a few years since I've worked with primary students and even then I have found myself making errors in using performance charts, sometimes my students would point out my errors which I humbly accepted as a learning experience.


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## Thumpalumpacus (Jul 23, 2021)

XBe02Drvr said:


> Jees, only forty more pages to the big two double oh! Think we can make it?



This thread might have more pages than the -39 had kills.

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## Snautzer01 (Jul 23, 2021)

Thumpalumpacus said:


> This thread might have more pages than the -39 had kills.



The European one had some. Not the African one. That shifted CoG to much after the coconots were installed.

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## FLYBOYJ (Jul 23, 2021)

Thumpalumpacus said:


> This thread might have more pages than the -39 had kills.


In the USAAF - 

I've been trying to find out what the kill/ loss ratio the VVS had against the Luftwaffe with the P-39.


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## XBe02Drvr (Jul 23, 2021)

FLYBOYJ said:


> As a young kid I would love to get my hands on a flight manual and just drool all over it in hopes of becoming an expert on said airplane. There were many terms and references in these manuals that I glossed over and it wasn't until years later when I first took ground school how some of this data came together in my brain.


As a teenager I was the ultimate nerdy, irritating, PITA and drove those truly in the know totally bonkers with my Martin Caidin level of informational certainty. I see a fellow traveler in our X-spurt friend here. It wasn't til I actually started flying and those crusty old Chief Petty Officers who instructed in the flying club took me down a peg, that I began to see the light.

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## pbehn (Jul 23, 2021)

FLYBOYJ said:


> V speeds, density altitude, basic weight and balance, engine performance charts are some things most people will not firmly grasp by reading flight manuals for high performance aircraft, be that from WW2 or today without some kind of basic education on said subject matter. It's been a few years since I've worked with primary students and even then I have found myself making errors in using performance charts, sometimes my students would point out my errors which I humbly accepted as a learning experience.


From what I gathered from reading "stuff" that was the start of things with operational combat pilots. Most pilots could state how much fuel they had when they landed because that was part of operations, to constantly update how the theory compared to the practice.

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## Thumpalumpacus (Jul 23, 2021)

XBe02Drvr said:


> No Airplane Flight Manual is meant to be a "Piloting for Dummies" course on learning to fly. It assumes a level of airmanship appropriate to the airplane in question, something the untrained "armchair pilot" is woefully unprepared for. What said imaginary aviator lacks is the context to functionally interpret the information presented. He doesn't know how much he doesn't know and thinks he knows all he needs to know.



I had actually considered putting, into that post of mine you quoted, Cheney's reminder that "there's what we know, there's what we know we don't know, and there's what we do not know we don't know." It ties back to the Eastwood "a man's got to know his limitations" clip I posted earlier.

If you haven't been on stage -- in a cockpit, concert-stage, or whatever -- critique is easy. But when you're the one who has to crash and burn, a healthy dollop of humility is useful.

It's a pity 

 P-39 Expert
doesn't keep that in mind. Mile in your moccasins, and all that.

Thankfully, f**king up a gig doesn't give me a burning hole in the ground, with my dumb ass sitting in the middle of it. Folks should keep that in mind when they wish to lecture others.

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## Thumpalumpacus (Jul 23, 2021)

Snautzer01 said:


> The European one had some. Not the African one. That shifted CoG to much after the coconots were installed.



If you spelled it "cocon*u*ts", you'd lose about three pounds of ballast and perhaps it could fly!

That over-top "O" messes with CoG, bro.

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## XBe02Drvr (Jul 23, 2021)

pbehn said:


> Most pilots could state how much fuel they had when they landed because that was part of operations, to constantly update how the theory compared to the practice.


I hope our friend is a good swimmer. I get the feeling he may need that skill if he were to go flying in his P39.

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## Thumpalumpacus (Jul 23, 2021)

FLYBOYJ said:


> In the USAAF -
> 
> I've been trying to find out what the kill/ loss ratio the VVS had against the Luftwaffe with the P-39.



It's a mystery to me. I've read that the P-39 was the most successful American fighter (flown by any nation) of them all. I find that hard to believe, considering especially F6F had so many in 44-45. Another thing is that I don't really trust Soviet records myself, but who else do we ask, right?

Quite frankly, I'd trust LW records more than VVS from this era.

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## buffnut453 (Jul 23, 2021)

Thumpalumpacus said:


> It's a mystery to me. I've read that the P-39 was the most successful American fighter (flown by any nation) of them all. I find that hard to believe, considering especially F6F had so many in 44-45. Another thing is that I don't really trust Soviet records myself, but who else do we ask, right?
> 
> Quite frankly, I'd trust LW records more than VVS from this era.



Surely the poor old Buffalo has to be up there in terms of success rates. Even including all operational users, it still attained a 26:1 kill:loss ratio....largely due to the Finns, of course (and I should note those are claims rather than indisputable kills).

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## SaparotRob (Jul 23, 2021)

XBe02Drvr said:


> I hope our friend is a good swimmer. I get the feeling he may need that skill if he were to go flying in his P39.


That's only if the basement floods.

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## Glider (Jul 23, 2021)

XBe02Drvr said:


> Jees, only forty more pages to the big two double oh! Think we can make it?


Does anyone doubt it?


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## Snautzer01 (Jul 23, 2021)

Thumpalumpacus said:


> Quite frankly, I'd trust LW records more than VVS from this era.


That would be a mistake.

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## Thumpalumpacus (Jul 23, 2021)

buffnut453 said:


> Surely the poor old Buffalo has to be up there in terms of success rates. Even including all operational users, it still attained a 26:1 kill:loss ratio....largely due to the Finns, of course (and I should note those are claims rather than indisputable kills).



Brotha, I don't have the info to say anything contrary, but I won't lie, I'm skeptical of that.

Truth be told, it'd be cool if you twisted this thread into a discussion about the Buff, because everything here feels a little tired. So what've you got? Where am I selling you and 

 SaparotRob
short?

Anything's better than this groundhogging, and I'll take the blame for going off-topic.

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## Thumpalumpacus (Jul 23, 2021)

Snautzer01 said:


> That would be a mistake.



I welcome any correction you or others might have; and it would make this thread even more productive.

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## pbehn (Jul 23, 2021)

Thumpalumpacus said:


> It's a mystery to me. I've read that the P-39 was the most successful American fighter (flown by any nation) of them all. I find that hard to believe, considering especially F6F had so many in 44-45. Another thing is that I don't really trust Soviet records myself, but who else do we ask, right?
> 
> Quite frankly, I'd trust LW records more than VVS from this era.


It may well be the most successful US fighter flown by other nations than the USA, but there were a lot of them. Then there is the thorny issue of "success", the Mustang MkI, IA and Mk II would still have been a complete success if it never shot an enemy plane down.

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## buffnut453 (Jul 23, 2021)

Thumpalumpacus said:


> Brotha, I don't have the info to say anything contrary, but I won't lie, I'm skeptical of that.
> 
> Truth be told, it'd be cool if you twisted this thread into a discussion about the Buff, because everything here feels a little tired. So what've you got? Where am I selling you and
> 
> ...



The Finns alone managed a 32:1 kill/loss tally, claiming 459 shot down for only 15 air combat losses (Source: Finnish Air Force - Wikipedia). Yes, I know it's Wiki but the numbers tally pretty well with the Keskinen and Stenman 2-volume work on the Brewster in Finnish service (they claim 33:1), which is the most comprehensive history of the type in Finland. I trust the authors' research.

The Commonwealth squadrons in Malaya and Singapore claimed 67 kills (with a further 34 claimed as Probables) for 28 air combat losses (Source: "Buffaloes Over Singapore", Cull et al). Somewhere I have numbers for 67 Sqn that was in Burma but I can't locate the details right now.

So...yes, I think the 26:1 kill:loss ratio is pretty solid for the poor old Buffalo.

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## GregP (Jul 23, 2021)

FLYBOYJ said:


> In the USAAF -
> 
> I've been trying to find out what the kill/ loss ratio the VVS had against the Luftwaffe with the P-39.


Hi FlyboyJ. I have a Soviet Ace list, but it doesn't say what aircraft the pilot was flying. It DOES list the unit, but I don't have a list of what units flew what aircraft. More importantly, I don't have a timeline of each victory claim, so even if I DID have a list of which unit flew which aircraft at what time, it could not be matched up by the victory list.

In fact, the world Ace list I have is attached. Enjoy. The file isn't exactly finished since there are 2 or 3 countries absent, but working on things like this over time is slow. So, anyone who can add some data ... please DO SO! Oh, and, please reattach it in here or in a new thread.

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## Thumpalumpacus (Jul 23, 2021)

buffnut453 said:


> The Finns alone managed a 32:1 kill/loss tally, claiming 459 shot down for only 15 air combat losses (Source: Finnish Air Force - Wikipedia). Yes, I know it's Wiki but the numbers tally pretty well with the Keskinen and Stenman 2-volume work on the Brewster in Finnish service (they claim 33:1), which is the most comprehensive history of the type in Finland. I trust the authors' research.
> 
> The Commonwealth squadrons in Malaya and Singapore claimed 67 kills (with a further 34 claimed as Probables) for 28 air combat losses (Source: "Buffaloes Over Singapore", Cull et al). Somewhere I have numbers for 67 Sqn that was in Burma but I can't locate the details right now.
> 
> So...yes, I think the 26:1 kill:loss ratio is pretty solid for the poor old Buffalo.



What do you think made those numbers work? I'm ignorant, so forgive my dumb questions; I'm used to hearing about them being shot down in droves at Midway. What were we Americans missing that the Finns, or even RAF, got somewhat right?

This is an honest question, please don't take it otherwise.

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## buffnut453 (Jul 23, 2021)

Thumpalumpacus said:


> What do you think made those numbers work? I'm ignorant, so forgive my dumb questions; I'm used to hearing about them being shot down in droves at Midway. What were we Americans missing that the Finns, or even RAF, got somewhat right?
> 
> This is an honest question, pleas don't take it otherwise.



Not entirely sure I understand the question. Are you asking why did the Finns do so supremely well, and the Commonwealth didn't do too terribly?


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## Thumpalumpacus (Jul 23, 2021)

buffnut453 said:


> Not entirely sure I understand the question. Are you asking why did the Finns do so supremely well, and the Commonwealth didn't do too terribly?



... or why Americans did so poorly? Or why I might think that?


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## GregP (Jul 23, 2021)

The Finns used copious quantities of pixie dust  combined with Soviet aircrews that had little or outdated training and were not encouraged to do individual thinking. Many Soviet pilots, at first, were competent to fly the airplanes, but had never engaged is dissimilar air combat training of any sort, and were mostly low-time fliers. Many were also flying VERY outdated equipment until the production facilities were moved eastward and the Yak-3s and La-5s started coming off the lines.

Realistic training and FLIGHT TIME so the pilots were very familiar with their airplanes were a BIG factors. Maybe the Allies should have contracted with the Finns to fight the Germans!

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## pbehn (Jul 23, 2021)

Thumpalumpacus said:


> What do you think made those numbers work? I'm ignorant, so forgive my dumb questions; I'm used to hearing about them being shot down in droves at Midway. What were we Americans missing that the Finns, or even RAF, got somewhat right?
> 
> This is an honest question, please don't take it otherwise.


Its a case of what against what. Look at the figures the LW achieved in the early days of Barbarossa. Prior to WW2 starting the Soviet Union had more aircraft than the rest of the world combined.


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## buffnut453 (Jul 23, 2021)

Thumpalumpacus said:


> ... or why Americans did so poorly? Or why I might think that?



For the Finns, agree that training was key. They were very experienced and knew how to wring the most out of every aircraft that they operated. Interestingly, the Finnish Air Force had similar numbers of Brewsters and P-36s but the former returned better combat stats (the P-36 still wasn't shabby...just not quite as good as the Brewster). 

At Midway, VMF-221 lost 15 aircraft of 21 engaged. I think there are a number of reasons, including poor tactics (VMF-221 was still using Division tactics rather than the more tactically flexible pair and Thach Weave tactics that were emerging in the USN). The Squadron engaged in 5 Divisions, of differing sizes and at least one comprising a mix of F2A-3s and F4Fs, and the Divisions didn't all engage at once, but arrived in a rather piecemeal fashion. They were attacking a formation of 108 Japanese aircraft, including 36 A6Ms.

Also, around half of VMF-221 had only recently arrived at Midway. Not all of the new arrivals were green pilots just out of training but such a substantial change will affect unit cohesion in combat (the reason for such a large influx of new pilots was that VMF-221 was split in half to form a second squadron as the USMC desperately sought to expand its front-line strength). 

According to most accounts, the Japanese lost 11 aircraft in the Midway attack, with a further 14 heavily damaged and 29 slightly damaged. Traditional thinking is that most of the Japanese losses were due to AAA fire from Midway Island. However, it's entirely possible that some of the VMF-221 pilots who were killed managed to inflict some damage/losses on the Japanese formation. 

I'm afraid a lot of received wisdom about the Buffalo is derived from books that were released in the 1970s and simply trotted out the rather lazy assessment that they were shot down in droves. Martin Caiden in his Ragged, Rugged Warriors even quotes an Australian pilot who stated that his squadron was entirely wiped out...which never happened. Such epithets don't stack up when compared against contemporary operational records (I have done that research, including communicating with almost every surviving Buffalo pilot in the 1990s...including Bill Brooks, the last survivor from Midway, who was rather fond of the Buffalo).

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## FLYBOYJ (Jul 23, 2021)

GregP said:


> Hi FlyboyJ. I have a Soviet Ace list, but it doesn't say what aircraft the pilot was flying. It DOES list the unit, but I don't have a list of what units flew what aircraft. More importantly, I don't have a timeline of each victory claim, so even if I DID have a list of which unit flew which aircraft at what time, it could not be matched up by the victory list.
> 
> In fact, the world Ace list I have is attached. Enjoy. The file isn't exactly finished since there are 2 or 3 countries absent, but working on things like this over time is slow. So, anyone who can add some data ... please DO SO! Oh, and, please reattach it in here or in a new thread.


Hi Greg - great stuff, many thanks! I remember you talking about this over the years, pretty awesome! I might be able to extract some data from this, I think I remember reading somewhere that VVS P-39s claimed over 2,200 Luftwaffe aircraft. Hoping to verify this number and find out how many VVS P-39s were claimed by the Luftwaffe.

Maybe this is one area our "Expert" can accurately address.


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## GregP (Jul 23, 2021)

Hi FlyboyJ, I still have very LARGE files I could post, but some exceed the file size limit (or they did at the time, some years past).

I have an Excel file with data on over 1000 airplanes, 99% of which are WWII airplanes. But, it's 105 Mb in size, so it didn't use to be able to be posted. Maybe it can be now. Let me know.

Cheers.

Maybe we need a sticky thread for files we want to share with the forum? So everyone could find them?


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## FLYBOYJ (Jul 23, 2021)

GregP said:


> Hi FlyboyJ, I still have very LARGE files I could post, but some exceed the file size limit (or they did at the time, some years past).
> 
> I have an Excel file with data on over 1000 airplanes, 99% of which are WWII airplanes. But, it's 105 Mb in size, so it didn't use to be able to be posted. Maybe it can be now. Let me know.


Let me digest what you have - I know there's been some things updated on the site but don't know if a file that size could be downloaded. Many thanks for the offer!

Marcel or https://ww2aircraft.net/forum/members/wurger.1418/ may know the answer to this


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## GregP (Jul 23, 2021)

No problem. The entire population of WWII aviation enthusiasts isn't all THAT large, and is shrinking daily as we die off.

Why not share the information while there is still interest?

Again, maybe we need a sticky thread for sharing files. Alternately, I could PM YOU the file or files and YOU could upload it?

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## FLYBOYJ (Jul 23, 2021)

GregP said:


> No problem. The entire population of WWII aviation enthusiasts isn't all THAT large, and is shrinking daily as we die off.
> 
> Why not share the information while there is still interest?
> 
> Again, maybe we need a sticky thread for sharing files. Alternately, I could PM YOU the file or files and YOU could upload it?


Updated my response - let me ask the other guys who are a little bit more savvy than I


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## GregP (Jul 23, 2021)

Thanks!


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## Thumpalumpacus (Jul 23, 2021)

pbehn said:


> Its a case of what against what. Look at the figures the LW achieved in the early days of Barbarossa. Prior to WW2 starting the Soviet Union had more aircraft than the rest of the world combined.



I'm not sure of your point. It may well be the difference in experience -- LW vs VVS, IJN aviators vs inexperienced. Why did the Buffalo turn in good numbers in Finland, and rather weak in others? What advantages were Finnish pilots using that USMC at Midway, or RAF in Malaya, weren't?


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## Thumpalumpacus (Jul 23, 2021)

buffnut453 said:


> I'm afraid a lot of received wisdom about the Buffalo is derived from books that were released in the 1970s and simply trotted out the rather lazy assessment that they were shot down in droves.



This is really what I'm questioning, in my own thinking, here; and wanting what are obviously informed opinions on the matter.


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## buffnut453 (Jul 23, 2021)

Thumpalumpacus said:


> This is really what I'm questioning, in my own thinking, here; and wanting what are obviously informed opinions on the matter.





 jimmaas
is the real expert on the Buffalo. I just jumped on his coat tails and focused on the Commonwealth use of the Buffalo. Over the years, I've written to or met a large number of former Buffalo pilots, and was also able to obtain records from surviving relatives of several deceased Buffalo pilots. I've probably mentioned it before but my avatar is a painting by Nick Trudgian I had commissioned as a present to myself when I retired from the RAF. It depicts the air battle over Kuala Lumpur on 22 Dec 1941 based on a type-written description provided by Harry Griffiths. Harry's Buffalo was serial W8231 "TD-G" and it had the name "Shirley" on the nose. Shirley was Harry's wife...and it was Shirley that typed up his letter to me. Those letters are among my most treasured possessions. 

Then there's the hours I spent at the UK National Archives exploring Operations Record Books as well as other records that survived from Singapore, Malaya and Burma. Almost all my material is currently in storage...but I hope to get back to it within the next 6 months.

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## pbehn (Jul 23, 2021)

Thumpalumpacus said:


> I'm not sure of your point. It may well be the difference in experience -- LW vs VVS, IJN aviators vs inexperienced. Why did the Buffalo turn in good numbers in Finland, and rather weak in others? What advantages were Finnish pilots using that USMC at Midway, or RAF in Malaya, weren't?


Because compared to its opposition the Buffalo in Finland was an advanced aircraft. In the first three days of Barbarossa the Soviet Union lost 1,200 aircraft destroyed in the air and on the ground. During the Battle of Kursk, remembered as a tank battle the Soviets lost 3,000 aircraft in approximately 7 weeks.


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## buffnut453 (Jul 23, 2021)

pbehn said:


> Because compared to its opposition the Buffalo in Finland was an advanced aircraft. In the first three days of Barbarossa the Soviet Union lost 1,200 aircraft destroyed in the air and on the ground. During the Battle of Kursk, remembered as a tank battle the Soviets lost 3,000 aircraft in approximately 7 weeks.



Only at the beginning. The Brewster was still scoring kills against Hurricanes, P-40s, LaGG-3s, La-5s, and even several Spitfires, during its combat career (not to mention a couple of P-39s).

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## Thumpalumpacus (Jul 23, 2021)

pbehn said:


> Because compared to its opposition the Buffalo in Finland was an advanced aircraft. In the first three days of Barbarossa the Soviet Union lost 1,200 aircraft destroyed in the air and on the ground. During the Battle of Kursk, remembered as a tank battle the Soviets lost 3,000 aircraft in approximately 7 weeks.



I'm not sure how the first three days of Barbarossa translates to the Winter War. And I doubt the Finns flew Buffaloes at Kursk. I'm asking a specific question: why did the Buffalo turn in such good numbers in Finland, while sucking hind-teat elsewhere?


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## pbehn (Jul 23, 2021)

Thumpalumpacus said:


> I'm not sure how the first three days of Barbarossa translates to the Winter War. And I doubt the Finns flew Buffaloes at Kursk. I'm asking a specific question: why did the Buffalo turn in such good numbers in Finland, while sucking hind-teat elsewhere?


You have a habit of doing this in discussion, so before you say you wont talk to me any more I will do the same. The Soviets not caring a damn about losses may have been a big factor in how many losses they had, was my point, its quite a simple one really. Unlike their opponents loses didnt matter, only winning.


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## Thumpalumpacus (Jul 23, 2021)

buffnut453 said:


> jimmaas
> is the real expert on the Buffalo. I just jumped on his coat tails and focused on the Commonwealth use of the Buffalo. Over the years, I've written to or met a large number of former Buffalo pilots, and was also able to obtain records from surviving relatives of several deceased Buffalo pilots. I've probably mentioned it before but my avatar is a painting by Nick Trudgian I had commissioned as a present to myself when I retired from the RAF. It depicts the air battle over Kuala Lumpur on 22 Dec 1941 based on a type-written description provided by Harry Griffiths. Harry's Buffalo was serial W8231 "TD-G" and it had the name "Shirley" on the nose. Shirley was Harry's wife...and it was Shirley that typed up his letter to me. Those letters are among my most treasured possessions.
> 
> Then there's the hours I spent at the UK National Archives exploring Operations Record Books as well as other records that survived from Singapore, Malaya and Burma. Almost all my material is currently in storage...but I hope to get back to it within the next 6 months.



I'm very open to learning from someone who knows better. 

I'll go do some googling and stop bothering folks here. All replies have been appreciated.


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## Thumpalumpacus (Jul 23, 2021)

pbehn said:


> You have a habit of doing this in discussion, so before you say you wont talk to me any more I will do the same. The Soviets not caring a damn about losses may have been a big factor in how many losses they had, was my point, its quite a simple one really.



Have your people contact my people. Maybe we can do lunch.

Not sure why you took this personal, and I'm not sure I care. <shrug>


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## pbehn (Jul 23, 2021)

Thumpalumpacus said:


> Have your people contact my people. Maybe we can do lunch.
> 
> Not sure why you took this personal, and I'm not sure I care. <shrug>


Because you have pulled the "I wont talk to you anymore" thing three times before with me and with several other posters that I have seen. I dont take it personal I just dont see where your line of argument leads to. You may not see how the Soviets losing 1,200 planes in three days and shrugging their shoulders and carrying on is significant but I and others do. As far as uncle Joe was concerned it was a few hundred pilots and he was losing soldiers by the million.


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## GrauGeist (Jul 23, 2021)

At the Battle of Midway, one of the few times the USN's F2A engaged enemy forces, the Buffalo suffered due to inexperienced pilots who were trained in older methods of engagement as well as being up against a superior fighter piloted by seasoned combat veterans. Remember that Japan had been at war for over four years before the U.S. entered the conflict.
At Midway, all U.S. elements suffered greatly: USN, USMC and Army.
This was not because of inferior equipment or lack of sacrifice, it was due to inexperience and an outdated aerial combat model.
1942 saw the U.S. undertake a massive learning curve in how to counter IJN and IJA aircraft types and their tactics.

In the CBI, the Buffalo in Commonwealth service fared a little better due to tactics plus the IJN was still operating the A5M and the IJA was still operating the KI-27, which the Buffalo was capable of mastering.

In Finland, the Buffalo was capable of besting Soviet types due to their lack of experience and cohesive tactics. The Finnish pilots also had a high level of determination that enabled them to get the best out of any aircraft they flew, whether it be a MS.406, a Bf109 or anything In between.

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## Thumpalumpacus (Jul 23, 2021)

pbehn said:


> Because you have pulled the "I wont talk to you anymore" thing three times before with me and with several other posters that I have seen. I dont take it personal I just dont see where your line of argument leads to. You may not see how the Soviets losing 1,200 planes in three days and shrugging their shoulders and carrying on is significant but I and others do. As far as uncle Joe was concerned it was a few hundred pilots and he was losing soldiers by the million.



I was asking a question specifically about the Brewster. Do you have an answer to my question? I've yet to see it.

Just in case you've forgotten, in your little lather, my question is:



Thumpalumpacus said:


> What were we Americans missing that the Finns, or even RAF, got somewhat right?
> 
> This is an honest question, please don't take it otherwise.



If you can answer that, great. And if you can't, stop trying to showboat. It's unseemly and should be beneath you.

Now -- your answer? What did the Finns or even the RAF in Malaya get right that we Americans got wrong?

Bueller? Bueller?


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## Shortround6 (Jul 23, 2021)

Thumpalumpacus said:


> I'm ignorant, so forgive my dumb questions; I'm used to hearing about them being shot down in droves at Midway. What were we Americans missing that the Finns, or even RAF, got somewhat right



The Droves at Midway were actually TWO Marine Corp squadrons which had a few F4Fs thrown in. I am sure some of the other members know but I seem to remember 13 or fewer Buffaloes at Midway? Flown by mostly green pilots? It was all over in a few hours at best or perhaps well under an hour. 

That was the full and total extent of their air to air combat in US service except for four F2A-3s shooting down a Japanese flying boat on March 10th 1942. 

As mentioned earlier you had the RAF in Burma and the Dutch had received 72 Buffaloes at the time they went into action. How many were in service? 
A later Dutch order was not completed in time. 

What the Americans seemed to miss was don't send green pilots up against veterans and don't get bounced from above. 

F2A had been out of production for several months at the time of Midway so pulling the survivors from combat areas didn't affect things much.

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## pbehn (Jul 23, 2021)

Thumpalumpacus said:


> I was asking a question specifically about the Brewster. Do you have an answer to my question? I've yet to see it.
> 
> Just in case you've forgotten, in your little lather, my question is:
> 
> ...


I did, you just read what you want to and ignore what doesnt fit. tally up all the kills made by Buffalos and all the losses in the air in that whole war and tell me why Uncle Joe would care at all. The Finns had skilled pilots, what they got right was they were fighting the Russians. There were only 500 Buffaloes made about a tenth went to Finland, the various loss and kill ratios are from a small squadron sized sample. It should have been better than the Spitfire and Hurricane, it was a later aircraft.


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## BiffF15 (Jul 23, 2021)

Clayton Magnet said:


> Hate those Janitrols!


I did my ATP in a Piper Seminole in 1996. It had a Janitrol heater…

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## wuzak (Jul 23, 2021)

This must be an overnight record - 6 more pages!

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## wuzak (Jul 23, 2021)

I think the problem for the Buffalo is that no long lost performance tests have been discovered and posted at WWII Aircraft Performance and so its reputation hasn't been restored.

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## ThomasP (Jul 24, 2021)

re the Stewart Warner gasoline heaters, and when/what AC used them

In the maintenance manuals the actual heaters under discussion are called Stewart Warner Hermetic Combustion heaters - from here on indicated by the acronym SWHC followed by the Model number and BTU output if available. The heaters themselves used a fuel-air mixture connection ported from the supercharger.

USAAF P-39C thru D-1 and UK P-400 used 1(?)x SWHC Model ? ? BTU unit. (I could not find the model number so I do not know any details.)
NOTE that the Soviet P-39 manuals mention the Stewart Warner heaters also, along with another type of combustion heater, plus electric heaters (in effect space heaters) adapted for the P-39.

USAAF A-36A-1 Apache/Mustang, P-51A-1&A-5 Mustang, and UK Mustang Mk I&IA, used 2x SWHC Model ? 10,000 BTU unit (with integral blower), 1x in each wing (just outboard of the guns) for heating of wing guns only. The gun heating system was switched to electric heaters starting with the P-51A-2/A-10 series and continued through all subsequent models. An air duct/tube system using warm air from behind the engine was used in all models from the first production airframe.

USAAF A-20C thru G-10 used 1x SWHC Model 791-D 40,000 BTU unit for cabin heating. 1x 8500 BTU unit was used to heat the guns in gun nose models.
USAAF A-20G-20 on used 2x SWHC Model 791-D 40,000 BTU units to heat the cabin, and electric heaters to heat the guns.
(UK Boston AC used the same heaters as the equivalent USAAF airframes.)

USAAF B-25C/D (early- to mid-war) equipped for cold weather used 2x units, 1x SWHC Model 790-C 80,000 BTU and 1x Model 791-D 40,000 BTU.
USAAF B-25H-5 and B-25J (late-war) equipped for cold weather used 3x SWHC Model 906-A 50,000 BTU units. (7" dia x 17.5" L)
(UK Mitchell AC used the same heaters as the equivalent USAAF airframes.)

USAAF B-24C thru H, PB4Yx, and UK Liberator II thru VI, used 6x SWHC Model 789-F and/or -G units (all of 8,500 BTU output with integral blowers). (NOTE: Some late models of B-24 had a ducted air system, which used the engine heat for warming the cabin and de-icing.)

Early production USN and RAF PBY-5A used 1x SWHC Model 792-A 80,000 BTU unit with its own dedicated 1.4 HP motor. It was used for heating the cabin, and could be used for warming up an engine before start if necessary. Late production PBY-5A used a Skyheat Combustion Heater Model SGE-1 90,000 BTU unit with its own dedicated 2 HP motor. The Skyheat unit was retrofitted to most surviving USN airframes. A 1x SWHC Model 901-A 100,000 BTU unit was used on most airframes as a dedicated de-icing heater for the tail empennage.
USN and RAF PBY-5 used 1x SWHC Model 782-N 80,000 BTU unit with its own dedicated 1.4 HP motor. It was used for heating the cabin, and could be used for warming up a cold engine before start if necessary. Some PBY-5 used the SWHC heater for the empennage.
NOTE that some PBY-5 and -5A were not fitted with the combustion heater systems, depending n the customer's order and intended area of operations.

I have found non-specific data for Stewart-Warner heaters used in aircraft up through the B-36 bomber, along with another type with the name including the word Norman.

NOTE that the above is what I found with a few hours searching.

Model 792-G 20,000 BTU unit weighed 27 lbs for the heater unit alone.

Model 940 20,000 BTU unit (immediate post-war, used by Piper) weighed 21 lbs for the heater unit alone.

The draw-thru blower motor weighed an additional 5 lbs according to the weight and loading charts. There would be 1x blower motor per heater. You would have to add the ducting and wiring/control box to get the overall installation weight.

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## buffnut453 (Jul 24, 2021)

GrauGeist said:


> In the CBI, the Buffalo in Commonwealth service fared a little better due to tactics plus the IJN was still operating the A5M and the IJA was still operating the KI-27, which the Buffalo was capable of mastering.



Not quite. There were only a few A5Ms in French Indochina used as hacks by the IJN's 22nd Air Flotilla. There's no record of the Commonwealth Buffalos ever engaging the A5M in combat. The primary IJN fighter in theatre was the A6M (although, granted, not very many of them) and they were mainly used against the Singapore defences. 

The Ki-27 was the most numerous IJA fighter over Malaya, Singapore and Burma but it was primarily used to defend airfields and resupply routes. The IJA's main fighter during the entire campaign was the Ki-43 of which they had two Sentais (note a Sentai is equivalent to a wing not a squadron). The Ki-43 was used in "aerial exterminating action" which today we'd call Offensive Counter Air. It was the Ki-43 that did all the damage against the Buffalos during the advance down the Malaya peninsula.

The Japanese planned their campaign very well. Taking Thailand first enabled them to use their Ki-43s to support operations in south into Malaya and west into Burma simultaneously, while cutting the ability of the RAF to move resources between those countries.

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## buffnut453 (Jul 24, 2021)

pbehn said:


> There were only 500 Buffaloes made about a tenth went to Finland, the various loss and kill ratios are from a small squadron sized sample. It should have been better than the Spitfire and Hurricane, it was a later aircraft.



Well...a wee bit more than a squadron-sized sample. Plus the Buffalo was in combat for a very long time: first kill was 25 June 1941 and the last was 3 October 1944. That's a pretty impressive record and testament to the skill not only of the Finnish pilots but also the maintenance crews who kept such a small force flying and combat-capable for so long.

Yes, the Buffalo flew later than either the Spitfire or Hurricane...but not by much. It was still a mid-ish 30s design and, like its contemporaries, suffered from lack of combat experience feeding into the design. It's key shortfall was lack of growth capacity. It was a small airframe and its design meant it was inherently limited from the very beginning. 

Probably the best thing the Buffalo did for the US was spur development of the F4F as a monoplane (the XF4F-1 which the Brewster beat in competition was a biplane). It was still the first modern (with enclosed cockpit, retractable undercarriage, flaps etc), single-seat fighter to enter navy service anywhere in the world.

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## buffnut453 (Jul 24, 2021)

In case anyone cares, I took a look at the Keskinen and Stenman books and came up with the following Finnish claim totals against the more capable Soviet fighter types:

Hurricane: 54
Yak 1/7/9: 41
La 5: 21
Spitfire: 13

Even if any ONE of those types shot down ALL the 15 Finnish Brewster losses, it would still represent a solid performance by the Brewster. Of course we know that Brewsters were shot down by a range of different Soviet aircraft. 

The key thing is that pilot proficiency makes a huge difference in aircraft combat performance.

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## buffnut453 (Jul 24, 2021)

Just for fun, I went through Peter Boer's most excellent "Aircraft of the Netherlands East Indies Army Air Corps in Crisis and War Times, February 1937 to June 1942" (I heartily recommend this book, or any of Peter's other books, for anyone interested in the NEI fight against the Japanese). Boer comes up with 15 confirmed kills, 8 probables and 2 damaged for the loss of 20 Brewsters.

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## SaparotRob (Jul 24, 2021)

Great thread! Not so good for the P-39 but Buffalo lovers rejoice!

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## SaparotRob (Jul 24, 2021)

My dog's better than your dog. My dog's better than yours. My dog's better 'cause he eats Kennel-Ration! My dog's better than yours.

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## GregP (Jul 24, 2021)

Maybe what they really needed was a Buffalacobra. A combination, if you will, of the Buffalo and the AIracobra.

The main reason it never happened in real life is that the Airacobra was USAAF and the Buffalo was USN/MC. 

The plans were drawn up, but were lost during the 1939 Army-Navy football game when the two mascots got into a fight while near the plans that were on display. The Army mascot, a mule, ate about half of the plans. The Navy mascot was a goat and, naturally, could eat ANYTHING. Unfortunately, it did just that, and the Buffalacobra plans were never resurrected for production.

Another in a long line of "might have beens."

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## pbehn (Jul 24, 2021)

buffnut453 said:


> Well...a wee bit more than a squadron-sized sample. Plus the Buffalo was in combat for a very long time: first kill was 25 June 1941 and the last was 3 October 1944. That's a pretty impressive record and testament to the skill not only of the Finnish pilots but also the maintenance crews who kept such a small force flying and combat-capable for so long.
> 
> Yes, the Buffalo flew later than either the Spitfire or Hurricane...but not by much. It was still a mid-ish 30s design and, like its contemporaries, suffered from lack of combat experience feeding into the design. It's key shortfall was lack of growth capacity. It was a small airframe and its design meant it was inherently limited from the very beginning.
> 
> Probably the best thing the Buffalo did for the US was spur development of the F4F as a monoplane (the XF4F-1 which the Brewster beat in competition was a biplane). It was still the first modern (with enclosed cockpit, retractable undercarriage, flaps etc), single-seat fighter to enter navy service anywhere in the world.


As you say it was in service for a long time. The Finns ordered 44 aircraft with 10 replacement engines and 20 replacement propellers. I dont know what composed a Finnish squadron but even a 12 airplane RAF squadron was performing miracles keeping operational for over 3 years with 44 aircraft. AFAK only two squadrons operated the Buffalo but only one at any time. Fighter squadron 24 had them until May 1944 when they were transferred to Fighter squadron 26.
This is a good read.


Brewster F2A Buffalo - Operational History - Finland


Which contains this quote.
"The Brewster model 239 was good against the older Russian fighters, Polikarpov I-153 _Chaika_ (Gull) and I-16. Hence the period 1941–42 was the best time for us. In 1943 it was already significantly more difficult when the Russians began to use their newer fighters against us... Later, with the Yaks, Hurricanes, Tomahawks, LaGG-3 and MiGs, it became a fight to the death."

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## Glider (Jul 24, 2021)

pbehn said:


> As you say it was in service for a long time. The Finns ordered 44 aircraft with 10 replacement engines and 20 replacement propellers. I dont know what composed a Finnish squadron but even a 12 airplane RAF squadron was performing miracles keeping operational for over 3 years with 44 aircraft. AFAK only two squadrons operated the Buffalo but only one at any time. Fighter squadron 24 had them until May 1944 when they were transferred to Fighter squadron 26.
> This is a good read.
> 
> 
> ...


The RAF as a rule of thumb in Europe assumed that a front line squadron would need approx. 50 aircraft to stay operational for six months

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## pbehn (Jul 24, 2021)

Glider said:


> The RAF as a rule of thumb in Europe assumed that a front line squadron would need approx. 50 aircraft to stay operational for six months


Exactly, a fighter marque only stayed as the "front line top fighter" with the RAF for about six months anyway.


The Russians and those on the eastern front used a different spreadsheet with different priorities.
The same link has this quote
"On 18 August 1942 he was involved in one of the most successful sorties involving the Buffalo fighter. Lt Hans Wind with six other Buffalos of LeLv 24 intercepted some 60 Soviet aircraft near Kronstad. Two Russian Pe-2 bombers, one Soviet Hurricane fighter, and 12 I-16s were shot down with the loss of just one Buffalo B-239 (BW-378)."

So 7 interceptors bounced and downed 15 aircraft with a loss of one Buffalo a ratio of 1 to 15. But the quote doesnt say how many more Pe-2 bombers out of the 60 plane formation made it to complete the mission. On a different spreadsheet the tally would be 2 bombers lost one enemy interceptor destroyed. In the same way that Marseilles became a celebrated ace without shooting down a bomber and therefore having little effect of the actual war in N Africa, there are many ways of looking at statistics.

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## Glider (Jul 24, 2021)

pbehn said:


> Exactly, a fighter marque only stayed as the "front line top fighter" with the RAF for about six months anyway.
> 
> 
> The Russians and those on the eastern front used a different spreadsheet with different priorities.
> ...


Totally agree. A similar logic would be the British landings at Dieppe. No question that the RAF lost more aircraft than the Germans and a lot of people call it a victory for the Luftwaffe. But the landing forces approached the area, the landings took place and the withdrawal was completed with next to no interference from the Luftwaffe. Despite it being right on their doorstep, in other words the RAF did what they were supposed to do, a lesson often lost.

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## nuuumannn (Jul 24, 2021)

buffnut453 said:


> This seems to be a "dog watching tennis" situation.



On occasion, the dog stops and licks its balls. At least it has its priorities right.

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## nuuumannn (Jul 24, 2021)

buffnut453 said:


> The whole theory that the Brits deliberately added a gas heater to help increase the P-400's weight so they could get out of the contract is so ridiculous.



And this _after_ the reasons why the P-39 was rejected by the RAF has been stated here a few times already. The A&AEE actually commented favourably about the ease at which the P-39 could be landed, but found the cockpit cramped and visibility poor. To repeat, *the RAF didn't like the way the magnetic compass tumbled every time the guns were fired *and so rejected it despite a fix being found relatively soon afterwards, the A&AEE trials revealed that *its performance was inferior to the Spitfire V* and continuing unserviceability and unreliability of the aircraft already in service meant that the fate of the Airacobra in British hands was sealed.

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## pbehn (Jul 24, 2021)

Glider said:


> Totally agree. A similar logic would be the British landings at Dieppe. No question that the RAF lost more aircraft than the Germans and a lot of people call it a victory for the Luftwaffe. But the landing forces approached the area, the landings took place and the withdrawal was completed with next to no interference from the Luftwaffe. Despite it being right on their doorstep, in other words the RAF did what they were supposed to do, a lesson often lost.


The top LW ace scored about the same or more than the whole Finnish airforce using Buffalos in the whole war, and he was on the losing side. The numbers on the eastern front defy western logic, because Uncle Joe always knew he had more men and women than his opponent, an aeroplane was just a weapon and a pilot was just a person, no more or less valuable than any other.

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## Graeme (Jul 24, 2021)

Thumpalumpacus said:


> What do you think made those numbers work?



I've no idea how accurate this - Martin Gilbert from the 70's attributed the Finn's success with the Buffalo to good pilots, a better engine and a *ton* lighter (?)

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## pbehn (Jul 24, 2021)

The Buffalo fighters that were sent to Finland were *de-navalized*; before these fighters were placed onto ships for delivery to Finland, Brewster Company employees removed all the naval equipment on the fighters, such as their tailhooks and life-raft containers, resulting in a somewhat lighter aircraft. The Finnish F2A-1s further lacked self-sealing fuel tanks and cockpit armor.

These F2A-1 Buffalos, given the export number Model B-239, were equipped with an export-approved Wright R-1820-G5 nine-cylinder radial engine of 950 hp (708 kW). After their delivery to Finland, the Finnish Air Force added armored backrests for their pilots, metric flight instruments, the Finnish Väisälä T.h.m.40 gunsight, and four .50 in (12.7 mm) machine guns. The top speed of the Finnish Buffalos, as modified, was 297 mph (478 km/h) at 15,675 ft (4,750 m), and their loaded weight was 5,820 lb (2,640 kg).

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## FLYBOYJ (Jul 24, 2021)

nuuumannn said:


> *the RAF didn't like the way the magnetic compass tumbled every time the guns were fired *


In the day this was a huge issue as there were little to no navigation aids installed in fighters at that time (you had the few that got an ADF). Your Directional Gyro was set was continually set to the mag compass (as it precessed every several minutes) and most of your navigation was done by Dead Reckoning. Then again with IFF you might be vectored back to base if you were identified by someone tracking you, but I won't even get into that!

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## nuuumannn (Jul 24, 2021)

FLYBOYJ said:


> Then again with IFF you might be vectored back to base if you were identified by someone tracking you, but I won't even get into that!


Did you read the manuals, Joe...

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## nuuumannn (Jul 24, 2021)

FLYBOYJ said:


> In the day this was a huge issue as there were little to no navigation aids installed in fighters at that time (you had the few that got an ADF). Your Directional Gyro was set was continually set to the mag compass (as it precessed every several minutes) and most of your navigation was done by Dead Reckoning.


I have asked the expert when the USAAF discovered this was happening and what was done about it, but he didn't know. Is there any evidence this affected the P-39 in US service? The RAF did find a fix, apparently, but I don't know what it entailed.

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## pbehn (Jul 24, 2021)

This was not a minor issue, pilots disorientated after combat could easily get lost and run out of fuel before they found out where they were. The first Fw190 delivered into UK hands was an example of this, in combat over the Bristol Channel Armin Ferber flew north instead of south and thinking the Bristol Channel was the English Channel made a perfect landing in Pembrey Wales. 








Armin Faber - Wikipedia







en.wikipedia.org

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## PAT303 (Jul 24, 2021)

I've always wondered about navigation, after 10 minutes in a turning fight I'd be lost, I think I would stress more about being lost that being shot at.


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## P-39 Expert (Jul 25, 2021)

Shortround6 said:


> I do like the way the P-39 "escorts" clear the airfield fence, get the gear up, switch to the drop tank and head for Germany.
> 
> at some point in 1943 the P-47 groups changed number of aircraft per squadron to 25 aircraft. Or 75 planes for a 3 squadron group. even if not all planes are flying let's call it 50 planes operational on a given day. At 15 seconds between planes that is 12.5 minutes, at 20 seconds between planes that 16.7 minutes.
> 
> ...


Per Edwards Park in his book "Angels Twenty" form up was easy, planes took off in pairs, with the next pair starting takeoff roll as the previous pair were about halfway down the runway. Lead pair took a very wide swing to vector to target. Next pair took a little narrower swing, and on down through the last (8th) pair taking a short swing with all 16 planes in the squadron being in formation. Switch to drop tank was after gear/flaps were up and climb speed established.

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## pbehn (Jul 25, 2021)

P-39 Expert said:


> Per Edwards Park in his book "Angels Twenty" form up was easy, planes took off in pairs, with the next pair starting takeoff roll as the previous pair were about halfway down the runway. Lead pair took a very wide swing to vector to target. Next pair took a little narrower swing, and on down through the last (8th) pair taking a short swing with all 16 planes in the squadron being in formation. Switch to drop tank was after gear/flaps were up and climb speed established.


What do you mean "target"? are you off to Berlin on your own? Are there any clouds in your scenario? Or other escort squadrons?


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## P-39 Expert (Jul 25, 2021)

ThomasP said:


> I do not know if the following has been posted in this thread before, but for what it is worth:
> 
> View attachment 633283
> 
> ...


Thanks for posting. Hmmm, nowhere in these instructions from the flight manual is there mention of using the Takeoff, Climb and Landing chart to compute range. Nowhere. These instructions say to use the Flight Operations Instruction chart and refer to "Operating Data" which is a part of the Flight Operation Instruction Chart. Operating Data is a little more than halfway down the chart in each column. No mention of the Takeoff, Climb and Landing chart at all.

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## P-39 Expert (Jul 25, 2021)

SaparotRob said:


> Just as an aside, could there have been an engine, post war, that could have been mounted in the P-39 airframe that would give it claimed performance? Not talking Reno Racers.
> I was even thinking of the jet engine that the Bee-Dee 5 had.


Nothing post war, but during the war the V-1710-85 engine in the P-39N gave performance sufficient to meet the guarantee. P-39N began production in November 1942. The V-1710-93 was the two stage model that was in production from April 1943 that would have given the P-39 (and P-40) excellent performance at high altitude.

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## pbehn (Jul 25, 2021)

P-39 Expert said:


> Nothing post war, but during the war the V-1710-85 engine in the P-39N gave performance sufficient to meet the guarantee. P-39N began production in November 1942. The V-1710-93 was the two stage model that was in production from April 1943 that would have given the P-39 (and P-40) excellent performance at high altitude.


You have made this point before and been given a list before of all the planes of superior performance that were in production before your P-39N, seriously, what is the point. Both the USA and British had Merlin engined P-51s flying before the end of Nov 1942. Then there are P-47s, P-38s, Griffon Spitfires, Spitfire Mk VII, VIII and Mk IX and of course the P-51A or P410 as I now prefer to call it.

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## Shortround6 (Jul 25, 2021)

Great, now what about squadrons 2 & 3 of the fighter group?
Mechanical difficulty in one plane?

At just over 70 Degrees F it takes a P-39Q with drop tank just over 2000ft to go wheels up (off the ground) and over 3000ft to get to over 50ft at sea level, even a few hundred feet starts to make a difference. 
I don't know how many seconds but if it takes 2000ft to get up to flying speed things aren't moving that quick. 

In the tropics it need greater distances. Even in England on a warm summer morning you could need more distance. 

But P-39s can form up group sized formations ever so much quicker than the British could with Spitfires in 1940, right?

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## FLYBOYJ (Jul 25, 2021)

P-39 Expert said:


> Switch to drop tank was after gear/flaps were up and climb speed established.


Vx or Vy?


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## FLYBOYJ (Jul 25, 2021)

P-39 Expert said:


> Thanks for posting. Hmmm, nowhere in these instructions from the flight manual is there mention of using the Takeoff, Climb and Landing chart to compute range. Nowhere. These instructions say to use the Flight Operations Instruction chart and refer to "Operating Data" which is a part of the Flight Operation Instruction Chart. Operating Data is a little more than halfway down the chart in each column. *No mention of the Takeoff, Climb and Landing chart at all.*


*And just because it doesn't mention it that doesn't mean you ignore it! *

Those who had an inkling of flight training would know this, even "Joe Pilots."

Take off/ landing, OK, *BUT NOT CLIMB!!!!*

It's great you read the manual!

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## FLYBOYJ (Jul 25, 2021)

P-39 Expert said:


> Nothing post war, but during the war the V-1710-85 engine in the P-39N gave performance sufficient *to meet the guarantee*. P-39N began production in November 1942. The V-1710-93 was the two stage model that was in production from April 1943 that would have given the P-39 (and P-40) excellent performance at high altitude.


What Guarantee? The one made back in 1940?


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## FLYBOYJ (Jul 25, 2021)

nuuumannn said:


> I have asked the expert when the USAAF discovered this was happening and what was done about it, but he didn't know. Is there any evidence this affected the P-39 in US service? The RAF did find a fix, apparently, but I don't know what it entailed.


It would be interesting to find out. Losing the accuracy of your compass would have been a huge issue during this period if you had no electronic navigation aid installed, to find your way home would have been totally dead reckoning.

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## pbehn (Jul 25, 2021)

Shortround6 said:


> Great, now what about squadrons 2 & 3 of the fighter group?
> Mechanical difficulty in one plane?
> 
> At just over 70 Degrees F it takes a P-39Q with drop tank just over 2000ft to go wheels up (off the ground) and over 3000ft to get to over 50ft at sea level, even a few hundred feet starts to make a difference.
> ...


Most WW2 UK airfields were constructed with 3 runways in a triangle, all of these runways were at a right angle to Berlin, well know internet fact. Planes could always take off into a headwind and turn right or left to the "target". The start of the BoB was fought in a glorious summer with clear skies, by September the LW was cursed with headwinds going to London, in the previously discussed October Jabo raids on London it was eventually the weather that called a halt, though there were many days in October that meant nothing happened. If you form up in close formation and climb into clouds you start hitting each other, I am not a pilot and I know that. Having climbed through cloud you have to find each other. The P-39N started to be introduced in November, so lets have some procedure for take off that takes into account November weather in UK.

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## Glider (Jul 25, 2021)

pbehn said:


> Most WW2 UK airfields were constructed with 3 runways in a triangle, all of these runways were at a right angle to Berlin, well know internet fact. Planes could always take off into a headwind and turn right or left to the "target". The start of the BoB was fought in a glorious summer with clear skies, by September the LW was cursed with headwinds going to London, in the previously discussed October Jabo raids on London it was eventually the weather that called a halt, though there were many days in October that meant nothing happened. If you form up in close formation and climb into clouds you start hitting each other, I am not a pilot and I know that. Having climbed through cloud you have to find each other. The P-39N started to be introduced in November, so lets have some procedure for take off that takes into account November weather in UK.


A small point of interest. In the UK there were two basic designs for airfields. Bomber bases had three runways and fighter fields had two. There were exceptions but they were few and far between.
The airfield close to where I live is one of those exceptions which is one reason why it housed the Turbinlite Bostons.

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## tyrodtom (Jul 25, 2021)

P-39 Expert said:


> Per Edwards Park in his book "Angels Twenty" form up was easy, planes took off in pairs, with the next pair starting takeoff roll as the previous pair were about halfway down the runway. Lead pair took a very wide swing to vector to target. Next pair took a little narrower swing, and on down through the last (8th) pair taking a short swing with all 16 planes in the squadron being in formation. Switch to drop tank was after gear/flaps were up and climb speed established.


What you're reading there is the dumbed down version of what they did, probably the publisher told the author " damn man, they don't have to know every detail " or something similar .
Can you imagine how far downrange the first pair would be by the time the last pair took off ?
It'd take a mighty wide turn by the early aircraft to compensate for that.
Could only work in perfect weather, wide enough runway, and small number of aircraft. 
How good do you think the taking off two by two idea works on a gusty day ?
How much luck do you think the late aircraft would have finding the early aircraft on a cloudy day ?

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## GregP (Jul 25, 2021)

P-39 Expert said:


> Nothing post war, but during the war the V-1710-85 engine in the P-39N gave performance sufficient to meet the guarantee. P-39N began production in November 1942. The V-1710-93 was the two stage model that was in production from April 1943 that would have given the P-39 (and P-40) excellent performance at high altitude.


No it wouldn't have, because there is not room in the P-39 airframe for a two-stage Allison.

There MIGHT be room for a 2-stage Merlin (a bit shorter), but the Merlin was never considered for the P-39, nor would it have been. The P-39 was an American airplane. The Merlin got into the P-51 simply because the British specified the P-51 and it WASN'T strictly an American airplane. You didn't see an Allison in a British airplane, other than the one (P-51) spawned in the U.S.A., did you?

Also, the Merlin was never built in a remote drive configuration like the E-series Allison was.

You have been told this repeatedly, by someone with access to actual P-39s. In fact, there are TWO P-39s at Chino airport, and neither of them have room for a 2-stage Allison engine. My thoughts are that since the P-39 were mass-produced, there wasn't room for a 2-stage Allison in ANY of them. When they needed a 2-stage Allison, they built the P-63, so it would fit. Maybe that's another 150-page thread, though.

Just saying.

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## wuzak (Jul 25, 2021)

P-39 Expert said:


> Per Edwards Park in his book "Angels Twenty"



Was that a factual book or fiction?


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## GrauGeist (Jul 25, 2021)

FLYBOYJ said:


> What Guarantee? The one made back in 1940?


I had to laugh at that.
It takes a manufacturer over two years to meet (barely) a promised performance level, during a war no less.
And then waiting another several months for a better engine to be developed.
Meanwhile, the war's half over and more advanced types are already in use...

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## FLYBOYJ (Jul 25, 2021)

"Taking off in pairs." Great on a training flight. Go to 0.45.

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## FLYBOYJ (Jul 25, 2021)

Shortround6 said:


> Great, now what about squadrons 2 & 3 of the fighter group?
> Mechanical difficulty in one plane?
> 
> At just over 70 Degrees F it takes a P-39Q with drop tank just over 2000ft to go wheels up (off the ground) and over 3000ft to get to over 50ft at sea level, even a few hundred feet starts to make a difference.
> ...


Pray for a headwind!


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## nuuumannn (Jul 25, 2021)

GregP said:


> When they needed a 2-stage Allison, they built the P-63, so it would fit.



Correct, Greg. The P-63 was built because of the limitations of the P-39. The mere existence of the P-63 makes a bit of a mockery of the claims made about the P-39's suitability for roles it was not considered for in reality.

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## buffnut453 (Jul 26, 2021)

Shortround6 said:


> Great, now what about squadrons 2 & 3 of the fighter group?
> Mechanical difficulty in one plane?
> 
> At just over 70 Degrees F it takes a P-39Q with drop tank just over 2000ft to go wheels up (off the ground) and over 3000ft to get to over 50ft at sea level, even a few hundred feet starts to make a difference.
> ...



Yeah...it's all well and good for a single fighter squadron operating independently....not so good for a Wing or Group-sized formation.

Also bear in mind that airfields in the southern UK were very close together. In Cambridgeshire, for example, you can hardly go 8 miles in any direction without hitting the site of a former WW2 airfield. There's a reason why so much attention was paid to forming up. 

And, as others have noted, add cloud to the mix and things get a whole lot more complicated. The first aircraft to take off MUST wait above the clouds for the rest of the formation to catch up. Formation flying through cloud is a mug's game.

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## Ascent (Jul 26, 2021)

buffnut453 said:


> Yeah...it's all well and good for a single fighter squadron operating independently....not so good for a Wing or Group-sized formation.
> 
> Also bear in mind that airfields in the southern UK were very close together. In Cambridgeshire, for example, you can hardly go 8 miles in any direction without hitting the site of a former WW2 airfield. There's a reason why so much attention was paid to forming up.


I can attest to this as a Cambridgeshire resident. I have a cycle route I do occasionally, it's about 40 miles in a loop and takes me right past 5 WWII bomber bases. If I get in my car a half hours drive will take me to a dozen more.

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## drgondog (Jul 26, 2021)

P-39 Expert said:


> Per Edwards Park in his book "Angels Twenty" form up was easy, planes took off in pairs, with the next pair starting takeoff roll as the previous pair were about halfway down the runway. Lead pair took a very wide swing to vector to target. Next pair took a little narrower swing, and on down through the last (8th) pair taking a short swing with all 16 planes in the squadron being in formation. Switch to drop tank was after gear/flaps were up and climb speed established.


In ETO, multiply that by three as Group level operations of 50+ (incl spares) were Norm. Warm up was 5+ minutes, take off in pairs every 30seconds, (24 minutes) for all in the air, 5+ minutes for all of the last squadron to hook up to the preceding two squadrons... so 34 minutes in great weather. 

BTW - that is optimistic for fuel consumption as the last squadrons are warming up and taxiing longer, while the early take offs are at Max Continuous after take off while forming up for longer period. Switch to drop tanks and continue Max Continuous for climb to altitude for cruise. 

Do more research on topic of escort operations.

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## DerAdlerIstGelandet (Jul 26, 2021)

drgondog said:


> In ETO, multiply that by three as Group level operations of 50+ (incl spares) were Norm. Warm up was 5+ minutes, take off in pairs every 30seconds, (24 minutes) for all in the air, 5+ minutes for all of the last squadron to hook up to the preceding two squadrons... so 34 minutes in great weather.
> 
> BTW - that is optimistic for fuel consumption as the last squadrons are warming up and taxiing longer, while the early take offs are at Max Continuous after take off while forming up for longer period. Switch to drop tanks and continue Max Continuous for climb to altitude for cruise.
> 
> Do more research on topic of escort operations.

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## SaparotRob (Jul 26, 2021)

Ascent said:


> I can attest to this as a Cambridgeshire resident. I have a cycle route I do occasionally, it's about 40 miles in a loop and takes me right past 5 WWII bomber bases. If I get in my car a half hours drive will take me to a dozen more.


Cool!


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## pbehn (Jul 26, 2021)

https://mediafiles.thedms.co.uk/publication/ee-eet/cms/pdf/information-sheets/USAAF%20Airfields%20Guide%20and%20Map.pdf#:~:text=Introduction%20During%20the%20Second%20World%20War%2C%20the%20East,were%20over%20100%2C000%20US%20airmen%20based%20in%20Britain.


Map here

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## drgondog (Jul 26, 2021)

P-39 Expert said:


> Thanks for posting. Hmmm, nowhere in these instructions from the flight manual is there mention of using the Takeoff, Climb and Landing chart to compute range. Nowhere. These instructions say to use the Flight Operations Instruction chart and refer to "Operating Data" which is a part of the Flight Operation Instruction Chart. Operating Data is a little more than halfway down the chart in each column. No mention of the Takeoff, Climb and Landing chart at all.


ThomasP tried to help you but UN-Like ALL others on this forum, you fart and fall down struggling with the concept maximum range versus Combat Radius. For the two links you reposted, you failed to note Range discussion in the Op manual, or instructions to look at the tables for a flight plan different from takeoff, cruise at a specific altitude/engine setting, and land - with fudge for 'reserve' to accommodate warm up, taxi, take off at MP, climb to altitude or return to what you thought might b your airfield -but reserve 20 gals 'just in case'. 

I'm curious - what make your mental processes so unique?

Maybe you should understand that CONTRACTOR developed operating tables, But AAF developed Combat Radius tables for Planning 'first cut' visibility to Potential Combat radius given the allocated circumstances - FOR SINGLE AIRPLANE, Perfect weather, No winds aloft, no changes in cruise altitude, engine operating settings or airspeed.

As Greg pointed out - neither the Allison with Aux supercharger, nor any Merlin (front or back) could be installed in a P-39 without exceeding CG limits - or maintaining aerodynamic shape or cooling system. Te closest to feasible change was the P-63 which had to be lengthened 2 1/2 feet. and total redesign of the aft fuselage/empennage and wing. 

What is sooooooo darned hard for you to find examples of ETO operations on Utube or internet, in which a mission is selected and planned - all the way down to fighter groups and their planning after receiving briefing for their assigned role. Look at Mission maps and see if you can find a straight line to a target longer than 200 miles. Look at films showing engine warm up at each assembly area (different depending on squadron take off assignment), taxi to active runway, form up in pairs, takeoff and circle for formation assembly - element by element, flight by flight in composed squadron - and repeat two more times, before setting course for climb destination. Add time for assembly/climb in the ever present crappy cloud cover/weather over England East Anglia - while dodging un-briefed RAF returns, recon flights, late forming 9th AF medium bomb groups forming around Bunchers.

You on the other hand, exercising extreme analytical abilities, see through all that BS and declare "Take off and seek der Foe, flee at first sight and return in tranquility" to stretch the P-39 to design parameter it could Never meet.

Find another audience for the Gospel - everyone else here is a Sinner.

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## Thumpalumpacus (Jul 26, 2021)

Personally, I prefer to feed troops into combat two at a time, so they can be defeated in detail. What the problem is?

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## SaparotRob (Jul 26, 2021)

pbehn said:


> https://mediafiles.thedms.co.uk/publication/ee-eet/cms/pdf/information-sheets/USAAF%20Airfields%20Guide%20and%20Map.pdf#:~:text=Introduction%20During%20the%20Second%20World%20War%2C%20the%20East,were%20over%20100%2C000%20US%20airmen%20based%20in%20Britain.
> 
> 
> Map here


Great link! I'd love to visit Attlebridge. I'd love to watch those turkeys forming up on the runway for take-off.

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## Ascent (Jul 26, 2021)

SaparotRob said:


> Cool!


Unfortunately there is very little to see on most of them, either returned to farmland or built on now but I do get to cycle down what was one of the runways at what was RAF Glatton, a B-17 base.

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## SaparotRob (Jul 26, 2021)

Still cool.


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## MikeMeech (Jul 26, 2021)

Ascent said:


> I can attest to this as a Cambridgeshire resident. I have a cycle route I do occasionally, it's about 40 miles in a loop and takes me right past 5 WWII bomber bases. If I get in my car a half hours drive will take me to a dozen more.


Hi

There are not many places in the UK that are vaguely 'flat' that were not used for airfields, the book 'Military Airfields in the British Isles 1939-1945 (Omnibus Edition)' by Willis and Holliss has brief details and small plans of 654, as at 1 December 1944. There cannot have been many places without an airfield circuit over them.

Mike

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## vikingBerserker (Jul 26, 2021)

I still go back to the question, if a number of countries using the P-39 were fighting for their existence why would the engineers and designers of the day not put the resources into "fixing" the aircraft into a formidable fighter instead of pouring even more resources and time into building and designing brand new fighters?

When you're drowning, most people try to fix the leaking life jacket they have instead of trying to design and build a new one.

I think this is just an example of "the simplest explanation is usually the best one", the life and abilities of the combat design was at its end.

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## GregP (Jul 26, 2021)

The P-39 was a pretty good airplane relative to the design parameters specified. It was reasonably fast and was OK at the altitudes where it was specified.

Unfortunately, the design spec was short-sighted and didn't address the realities of WWII, even though the WWII realities were apparent to most observers. The ETO was a high-altitude, longer-range theater of war, and the basic P-39 could not be modified to meet the new requirements. There was no place to add fuel and the engine was never developed into a 2-stage supercharged engine with two integral superchargers. Ironically, if the Allison HAD been developed into an integral 2-stage unit, it MIGHT have fit into a P-39 because it would have been considerably shorter than the aux-stage unit that was later developed. But it still had no place for added fuel and still had a CG problem.

I think you are correct above. It was recognized that the P-39 was useful in a niche mission, but it was not an airframe rich with development potential. So, they used it for what it could be used for, moved on, and got rid of it when better aircraft came along. That meant most any other fighter with some range and altitude capability along with a decent turn of speed. We'd likely have been better off with the same number of P-43 Lancers. At least there were no CG issues when the ammunition was used up.

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## GrauGeist (Jul 26, 2021)

In the end, the only way to upgrade the P-39, was to build an entirely new type as the P-63...

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## SaparotRob (Jul 26, 2021)

GrauGeist said:


> In the end, the only way to upgrade the P-39, was to build an entirely new type as the P-63...


And as you, and so many others have pointed out, might as well go with P-51's and P-47's and P-38's and....

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## buffnut453 (Jul 26, 2021)

Ascent said:


> I can attest to this as a Cambridgeshire resident. I have a cycle route I do occasionally, it's about 40 miles in a loop and takes me right past 5 WWII bomber bases. If I get in my car a half hours drive will take me to a dozen more.



Yep...lived for 15 years in Cambridgeshire, at Great Paxton and then Keyson, so I know the county well.


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## P-39 Expert (Jul 27, 2021)

GregP said:


> No it wouldn't have, because there is not room in the P-39 airframe for a two-stage Allison.
> 
> There MIGHT be room for a 2-stage Merlin (a bit shorter), but the Merlin was never considered for the P-39, nor would it have been. The P-39 was an American airplane. The Merlin got into the P-51 simply because the British specified the P-51 and it WASN'T strictly an American airplane. You didn't see an Allison in a British airplane, other than the one (P-51) spawned in the U.S.A., did you?
> 
> ...


Same amount of room in the P-39 as the P-63. Items would need to be rearranged, but it would fit. You have not proven a thing. I have continuously proven that both engine compartments were exactly the same size.


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## pbehn (Jul 27, 2021)

P-39 Expert said:


> Same amount of room in the P-39 as the P-63. Items would need to be rearranged, but it would fit. You have not proven a thing. I have continuously proven that both engine compartments were exactly the same size.


Well, someone has to ask the obvious question, why bother with the P-63?

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## P-39 Expert (Jul 27, 2021)

drgondog said:


> ThomasP tried to help you but UN-Like ALL others on this forum, you fart and fall down struggling with the concept maximum range versus Combat Radius. For the two links you reposted, you failed to note Range discussion in the Op manual, or instructions to look at the tables for a flight plan different from takeoff, cruise at a specific altitude/engine setting, and land - with fudge for 'reserve' to accommodate warm up, taxi, take off at MP, climb to altitude or return to what you thought might b your airfield -but reserve 20 gals 'just in case'.


The pilot's manual was very clear, no mention was made of using the Takeoff, Climb and Landing chart. Everything needed to plan a mission was on the Flight Operations Instruction Chart.


drgondog said:


> I'm curious - what make your mental processes so unique?
> 
> Maybe you should understand that CONTRACTOR developed operating tables, But AAF developed Combat Radius tables for Planning 'first cut' visibility to Potential Combat radius given the allocated circumstances - FOR SINGLE AIRPLANE, Perfect weather, No winds aloft, no changes in cruise altitude, engine operating settings or airspeed.
> 
> As Greg pointed out - neither the Allison with Aux supercharger, nor any Merlin (front or back) could be installed in a P-39 without exceeding CG limits - or maintaining aerodynamic shape or cooling system. Te closest to feasible change was the P-63 which had to be lengthened 2 1/2 feet. and total redesign of the aft fuselage/empennage and wing.


The two stage Allison would require a four blade propeller which would have offset the extra weight of the auxiliary stage. Ballast could have been used also if needed. I have said this numerous times in the auxiliary stage discussions.


drgondog said:


> What is sooooooo darned hard for you to find examples of ETO operations on Utube or internet, in which a mission is selected and planned - all the way down to fighter groups and their planning after receiving briefing for their assigned role. Look at Mission maps and see if you can find a straight line to a target longer than 200 miles. Look at films showing engine warm up at each assembly area (different depending on squadron take off assignment), taxi to active runway, form up in pairs, takeoff and circle for formation assembly - element by element, flight by flight in composed squadron - and repeat two more times, before setting course for climb destination. Add time for assembly/climb in the ever present crappy cloud cover/weather over England East Anglia - while dodging un-briefed RAF returns, recon flights, late forming 9th AF medium bomb groups forming around Bunchers.


I simply quoted an actual P-39 pilot in NG on how his squadron formed up for an actual mission. NG had lousy weather too. I have had discussions on this board comparing P-39 range with P-47 range (both with drop tanks) and these same calculations matched up very close to what combat radius maps indicated was the P-47's combat radius. P-39 radius was calculated the same way. In neither case was the Takeoff, Climb and Landing chart used. 


drgondog said:


> You on the other hand, exercising extreme analytical abilities, see through all that BS and declare "Take off and seek der Foe, flee at first sight and return in tranquility" to stretch the P-39 to design parameter it could Never meet.
> 
> Find another audience for the Gospel - everyone else here is a Sinner.


Thanks for your condescending and derogatory comments.

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## FLYBOYJ (Jul 27, 2021)

GregP, with no dog in the fight and access to "2" actual aircraft actually measures the aircraft and is told he wrong. 

"But I read the manual"

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## GrauGeist (Jul 27, 2021)

P-39 Expert said:


> Thanks for your condescending and derogatory comments.


You're lucky that's all you got.

You're arguing with historians, pilots and someone who actually has access to the actual aircraft and YET, you insist that your fatally flawed ideas are correct.

You state that you "read the manual" but clearly show that you have no idea how to use it...

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## FLYBOYJ (Jul 27, 2021)

P-39 Expert said:


> The pilot's manual was very clear, no mention was made of using the Takeoff, Climb and Landing chart. Everything needed to plan a mission was on the Flight Operations I


Says the non-pilot who read the manual.

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## PAT303 (Jul 27, 2021)

There is patient people, there are tolerant people, then there's you guys, if I ever go to war I want to fight with all of you, cool calm and professional against the most stubborn foe.

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## GregP (Jul 27, 2021)

I wonder if he is a member of the flat earth society ... I personally know 3 or 4 people who have sailed around the world without falling off the edge. But maybe that's hearsay.

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## pbehn (Jul 27, 2021)

FLYBOYJ said:


> Says the non-pilot who read the manual.


It is all taking on an air of comedy now.

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## drgondog (Jul 27, 2021)

P-39 Expert said:


> Same amount of room in the P-39 as the P-63. Items would need to be rearranged, but it would fit. You have not proven a thing. I have continuously proven that both engine compartments were exactly the same size.


Gently, use your vast analytical abilities and do a weights and balance chart for the the P-39Q (just the engine for simplicity) versus the P-63C.. Use the V-1710-85 at 1397# for the P-39 and V-1710-117-E21 at 1710#. Add Water Injection System weight of 50#(NOT INCLUDING WATER) and note that the empty weight has grown from ~ 5680 # (P-39Q) to 6850 (P-63C).

Especially notice that a.) The 'New mass' center moves to the rear as that is only possible space for auxiliary 2nd stage supercharger, and that b.) that the new mass of the new engine variant is not only greater by 360 pounds, but has moved at least least 6" rearward - in an airframe that already has major aft CG issues. and you have an empennage pitch control aerodynamic center at the same location from 'old P-39 CG' instead of installing a section aft of the cockpit to extend the empennage pitch control aerodynamic center - and haven't added vertical tail area to compensate for the yaw stability inherent in the P-63. 

Imagine the built in aft CG condition as 'best possible' flight condition which only deteriorates when forward stores are expended? Imagine the increase in pitch sensitivity and tendendcy for stick reversals at all speeds. Imagine that moving the CG aft from Center of Pressure of wing is destabilizing to pitch control 

Remember that you still have the small horizontal/vertical stabilizer of the P-39 (86% total Horizontal Stab Area of the P-63 H.Stab), a CG that has moved 6+in to rear of the production P-39Q.

In your infinite control of the pilot's operating manual is there a section that warns you about field mounting a 250 pound bomb under the engine compartment and asking a pilot to volunteer for the first flight?

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## buffnut453 (Jul 27, 2021)

pbehn said:


> It is all taking on an air of comedy now.



Remember when I posted the Blackadder clip several pages ago? Told ya so!!!

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## Glider (Jul 27, 2021)

P-39 Expert said:


> Same amount of room in the P-39 as the P-63. Items would need to be rearranged, but it would fit. You have not proven a thing. I have continuously proven that both engine compartments were exactly the same size.


As I am afraid we have all come to expect, you have proven nothing, absolutely nothing.

On one side we have the obvious, 
1) How come you know more than the tens of thousands of engineers who knew every inch or the aircraft
2) How do you know more than someone who actually has access to the real aircraft
3) How do you know more about the balance of the aircraft than the people who designed, built, flew and too often died in the aircraft.
4) How you know more about the range of the aircraft, than the people who flew it and planned the missions

On the other side we have
1) I read a manual (badly, incorrectly and with more than a little selectivity when picking details)

If you were neutral, which argument would you give credence too?

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## GregP (Jul 27, 2021)

He's not neutral. Definitely in P-39 gear.


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## P-39 Expert (Jul 27, 2021)

drgondog said:


> Gently, use your vast analytical abilities and do a weights and balance chart for the the P-39Q (just the engine for simplicity) versus the P-63C.. Use the V-1710-85 at 1397# for the P-39 and V-1710-117-E21 at 1710#. Add Water Injection System weight of 50#(NOT INCLUDING WATER) and note that the empty weight has grown from ~ 5680 # (P-39Q) to 6850 (P-63C).
> 
> Especially notice that a.) The 'New mass' center moves to the rear as that is only possible space for auxiliary 2nd stage supercharger, and that b.) that the new mass of the new engine variant is not only greater by 360 pounds, but has moved at least least 6" rearward - in an airframe that already has major aft CG issues. and you have an empennage pitch control aerodynamic center at the same location from 'old P-39 CG' instead of installing a section aft of the cockpit to extend the empennage pitch control aerodynamic center - and haven't added vertical tail area to compensate for the yaw stability inherent in the P-63.
> 
> ...


AUX stage SC weighed about 170lbs and replaced the coolant tank that was moved forward behind the pilot. Moving the carbueretor from the aux stage to normal position on the engine stage SC would move a little weight forward also. Heavier 4 blade propeller would offset the weight of the aux SC. May need some ballast, maybe not.


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## wuzak (Jul 27, 2021)

P-39 Expert said:


> AUX stage SC weighed about 170lbs and replaced the coolant tank that was moved forward behind the pilot. Moving the carbueretor from the aux stage to normal position on the engine stage SC would move a little weight forward also. Heavier 4 blade propeller would offset the weight of the aux SC. May need some ballast, maybe not.



Maybe the supercharger itself weight 170lbs, but what of the other bits and pieces to make it work, such as the extension shaft and hydraulic drive, step up gears, etc?

drgondog gave you the weights of a single stage V-1710 and a 2 stage V-1710, which was a difference of 360lb. You're only allowing for half that?

May need some ballast? Like nose armour, perhaps?


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## P-39 Expert (Jul 27, 2021)

wuzak said:


> Maybe the supercharger itself weight 170lbs, but what of the other bits and pieces to make it work, such as the extension shaft and hydraulic drive, step up gears, etc?
> 
> drgondog gave you the weights of a single stage V-1710 and a 2 stage V-1710, which was a difference of 360lb. You're only allowing for half that?
> 
> May need some ballast? Like nose armour, perhaps?


AHT says the P-39 engine weighed approx 1435lbs and the P-63 engine weighed 1620lbs. 185lbs difference.

Yes, the nose armor may be needed to be added back if ballast is needed.


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## pbehn (Jul 27, 2021)

wuzak said:


> Maybe the supercharger itself weight 170lbs, but what of the other bits and pieces to make it work, such as the extension shaft and hydraulic drive, step up gears, etc?
> 
> drgondog gave you the weights of a single stage V-1710 and a 2 stage V-1710, which was a difference of 360lb. You're only allowing for half that?
> 
> May need some ballast? Like nose armour, perhaps?


Why not use cast iron in the front fuselage? Cheaper and heavier, thats a real win-win.

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## SaparotRob (Jul 27, 2021)

pbehn said:


> Why not use cast iron in the front fuselage? Cheaper and heavier, thats a real win-win.


I never would have thought of that.


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## P-39 Expert (Jul 27, 2021)

Glider said:


> As I am afraid we have all come to expect, you have proven nothing, absolutely nothing.
> 
> On one side we have the obvious,
> 1) How come you know more than the tens of thousands of engineers who knew every inch or the aircraft


I don't and never claimed to.


Glider said:


> 2) How do you know more than someone who actually has access to the real aircraft


I have also had access to the real aircraft, the one at the CAF museum in San Marcos. And I have seen plans and diagrams. 


Glider said:


> 3) How do you know more about the balance of the aircraft than the people who designed, built, flew and too often died in the aircraft.


On this board we have diagrammed the balance many times.


Glider said:


> 4) How you know more about the range of the aircraft, than the people who flew it and planned the missions


There is a very simple chart in the pilot's manual. And reading Edwards Park's book about the P-39 in NG. And AHT, Vees for Victory, and many other reference books.


Glider said:


> On the other side we have
> 1) I read a manual (badly, incorrectly and with more than a little selectivity when picking details)


Have you read the manual? Read the Flight Information Instruction Chart? Figured range and radius for yourself?


Glider said:


> If you were neutral, which argument would you give credence too?


Almost all of my arguments reference an original source document such as a Wright Field performance test from wwiiaircraftperformance.org, a pilot's manual, or a reference book.

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## pbehn (Jul 27, 2021)

SaparotRob said:


> I never would have thought of that.


Thats where the logic of these arguments go. You dont just add a bit here and there. I remember seeing CoG calculations on a Spitfire stating how much it was changed by lowering the undercarriage. It was a fraction of an inch, but it was measured as all these things were. If you look at how it pivots the wheels move forward as they are lowered, that changes the CoG.

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## drgondog (Jul 27, 2021)

P-39 Expert said:


> AUX stage SC weighed about 170lbs and replaced the coolant tank that was moved forward behind the pilot. Moving the carbueretor from the aux stage to normal position on the engine stage SC would move a little weight forward also. Heavier 4 blade propeller would offset the weight of the aux SC. May need some ballast, maybe not.


Laughing loud at your ignorance. People who are stupid don't know they are stupid. DO THE EFFING MATH on the CG movement to install a heavier engine and supercharger/WI system in an airframe that required extending the length TWO FEET - Eight Inches behind the wing aerodynamic center - in order to move the H.Stab aerodynamic center Two feet further aft and increase the EFFING Empennage area 20% to be able to FLY the P-63 with the new engine/Water Injection. 

I have to admit that I have confronted the most clever troll or stupidest debater in my 75 years of reasonably enjoyable life. You should be proud - either way - as I have seen and met many of both types. My hat is off to you.

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## Shortround6 (Jul 27, 2021)

Unfortunately actual facts are ignored if contrary to the desired narrative. 

Yes the coolant tank was relocated. But it was the overflow/expansion tank. If I recall correctly it held 3 1/2 gallons (or 2 1/2?). 
This hardly compensates for the aux supercharger. The rest of the coolant stays in the engine and the radiator (original location/distance from CG).

This has been gone over before. 
But as usual the experts arguments revert back to the original misconceptions.

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## Thumpalumpacus (Jul 27, 2021)

GregP said:


> He's not neutral. Definitely in P-39 gear.



I think 
G
 Glider
meant to write "If you were *a* neutral *observer*" -- my suppositions in boldface.

Everyone here knows he isn't neutral, his username declares that.

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## GrauGeist (Jul 27, 2021)

So far we've covered every aspect except the weight of the marker lamps (nav lights) and the air pressure in the tires...

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## Thumpalumpacus (Jul 27, 2021)

GrauGeist said:


> So far we've covered every aspect except the weight of the marker lamps (nav lights) and the air pressure in the tires...



Wooden empennage. Don't forget the wooden empennage.

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## GrauGeist (Jul 27, 2021)

And maybe if there wasn't so many seat harness buckles...

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## wuzak (Jul 27, 2021)

P-39 Expert said:


> AHT says the P-39 engine weighed approx 1435lbs and the P-63 engine weighed 1620lbs. 185lbs difference.





Allison Piston Engine Specifications



Has 1660lb for the V-1710-117 (-E21) and 1450lb for the V-1710-85 (-E19).
The V-7101-81 (-F20R) of the P-51A weighed 1352lb, the V-1710-119 (-F32R) of the P-51J 1750lb.

Somehow the V-1710-121 (-F28R) in the P-40Q weighed only 1555lb!

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## FLYBOYJ (Jul 27, 2021)

P-39 Expert said:


> There is a very simple chart in the pilot's manual.


And with a host of pilots, some holding flight instructor's ratings and some ATPs have repeatedly shown you don't know how to use them. I recommend this, and I'm serious...









Chapter 11 specifically!



https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/phak/media/13_phak_ch11.pdf

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## FLYBOYJ (Jul 27, 2021)

P-39 Expert said:


> I have also had access to the real aircraft, the one at the CAF museum in San Marcos. And I have seen plans and diagrams.


Really? show us some pics or measurements to counter what GregP found when he actually measured the aircraft! Plans and diagrams? Did you know what you were looking at????


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## FLYBOYJ (Jul 27, 2021)

Thumpalumpacus said:


> Wooden *empennage*. Don't forget the wooden *empennage*.


About a month ago our friend didn't know what that meant

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## GrauGeist (Jul 27, 2021)

FLYBOYJ said:


> About a month ago our friend didn't know what that meant


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## Thumpalumpacus (Jul 27, 2021)

FLYBOYJ said:


> About a month ago our friend didn't know what that meant



Maybe he'll learn something despite himself. Maybe 
X
 XBe02Drvr
had a good point when he was explaining his patience upthread. As I've said, I come to this thread to learn too, and that's only because the pilots here provide a direct perspective. Thanks to all of ya for that.

His stubbornness has brought something useful to this thread, in a way he probably didn't imagine.

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## nuuumannn (Jul 27, 2021)

GrauGeist said:


> And maybe if there wasn't so many seat harness buckles...


What about changing aluminum map cases for plastic ones, like they did in the P-40? That'll give you at least an extra 30mph at 35,000ft, I reckon... 


FLYBOYJ said:


> I recommend this, and I'm serious...


True, received a copy in my first year of engineering course and referred to it frequently through my apprenticeship and whilst sitting licence papers. Got a stack of the airframe and propulsion manuals on my shelf and refer to them every now and then.

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## GrauGeist (Jul 27, 2021)

As has been mentioned before (way, way back upthread), he should get a ride just to see what all's involved in the process.
I'd offer to do it (if he lived nearby), but my certs are way out of date and I'm a VFR bottom-feeder compared to the other drivers in this discussion.

But I am serious - this guy needs a ride to get an idea of the "hows and whys".


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## SaparotRob (Jul 27, 2021)

GrauGeist said:


> As has been mentioned before (way, way back upthread), he should get a ride just to see what all's involved in the process.
> I'd offer to do it (if he lived nearby), but my certs are way out of date and I'm a VFR bottom-feeder compared to the other drivers in this discussion.
> 
> But I am serious - this guy needs a ride to get an idea of the "hows and whys".


Wait a minute. Could that have been his plan all along?

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## GrauGeist (Jul 27, 2021)

SaparotRob said:


> Wait a minute. Could that have been his plan all along?


By God, I think you're onto something, there!

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## Thumpalumpacus (Jul 28, 2021)

SaparotRob said:


> Wait a minute. Could that have been his plan all along?



Just wait -- two years from now we're going to read online about a guy who trolled an aviation forum into funding his flight lessons.

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## nuuumannn (Jul 28, 2021)

Thumpalumpacus said:


> Just wait -- two years from now we're going to read online about a guy who trolled an aviation forum into funding his flight lessons.



Could be worse, it could be about a guy who trolled an internet forum into believing him! 

Happens!

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## ThomasP (Jul 28, 2021)

re "Just wait -- two years from now we're going to read online about a guy who trolled an aviation forum into funding his flight lessons."

Hmmm . . .  ya know, I have always wanted to learn to fly.

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## drgondog (Jul 28, 2021)

P-39 Expert said:


> AUX stage SC weighed about 170lbs and replaced the coolant tank that was moved forward behind the pilot. Moving the carbueretor from the aux stage to normal position on the engine stage SC would move a little weight forward also. Heavier 4 blade propeller would offset the weight of the aux SC. May need some ballast, maybe not.
> AHT says the P-39 engine weighed approx 1435lbs and the P-63 engine weighed 1620lbs. 185lbs difference.
> 
> Yes, the nose armor may be needed to be added back if ballast is needed.



AHT - page 193, P-39Q. "Engine 1397", - page 410, P-63C, "Engine 1710" for tabulations for Empty weight. I assume Water Injection System weight (on 410) of 50 pounds is for the tank/lines and hopefully at CG as the Water/Alcohol usable weight is 185 pounds - which I assume is at CG (best case for 'tipping' consideration as follows). Total moment arm BEYOND datum line and original Fully loaded CG is added 313 pounds (minimum) and possibly another 215 pounds (water tank+water/alcohol);

The CG for the P-39 is forward of the main gear. Correct? Why you ask? Lean back in a chair. What happens when the 'new CG' moves past the support legs? The Door Hinge Line(aft) and pilot seat back are at the approximate seat back for full internal load. ALL additional 'Engine mass' is aft of the Pilot seat and CG with V-1710-85.

It DOESN'T help to put engine auxilliary 'bits' such as Water/Alcohol or Supercharger BEHIND the Seat, BEHIND the CG for the airplane at rest, to ADD to allowable full internal load. 

Imagine your new P-39 with P-63 engine/supercharger sitting on its ass in a classic three point config with nose gear dangling in he air.

If you can.

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## pbehn (Jul 28, 2021)

P-39 Expert said:


> AUX stage SC weighed about 170lbs and replaced the coolant tank that was moved forward behind the pilot. Moving the carbueretor from the aux stage to normal position on the engine stage SC would move a little weight forward also. Heavier 4 blade propeller would offset the weight of the aux SC. May need some ballast, maybe not.


If ballast was with 6 inch cannon balls this would be a major help to modellers. Lead shot and small ball bearings could be used in most scales. I am seeing lots of win-wins here.

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## Peter Gunn (Jul 28, 2021)

nuuumannn said:


> Could be worse, it could be about a guy who trolled an internet forum into believing him!
> 
> Happens!


At this point, I'd be curious if our P-39 buddy knows what CFI or ATP stands for, without a quick google search that is...

I wouldn't press too hard with stuff like VFR, IFR, IMC, VOR, VNE, ETC... well, maybe he knows the last one.

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## Peter Gunn (Jul 28, 2021)

Glider said:


> As I am afraid we have all come to expect, you have proven nothing, absolutely nothing.
> 
> On one side we have the obvious,
> 1) How come you know more than the tens of thousands of engineers who knew every inch or the aircraft
> ...


I'd give you double bacon for this if possible, although I'm jealous as I'm far too snarky to create such a well thought and direct to the point post. Well done.

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## special ed (Jul 28, 2021)

There was a company in Florida where you could buy a combat ride with an identical acft and find out how you would do for real. No Guns, but video.

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## SaparotRob (Jul 28, 2021)

special ed said:


> There was a company in Florida where you could buy a combat ride with an identical acft and find out how you would do for real. No Guns, but video.


That blows the doors off Epcot.

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## XBe02Drvr (Jul 28, 2021)

SaparotRob said:


> That blows the doors off Epcot.


...and your wallet!

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## pbehn (Jul 28, 2021)

drgondog said:


> AHT - page 193, P-39Q. "Engine 1397", - page 410, P-63C, "Engine 1710" for tabulations for Empty weight. I assume Water Injection System weight (on 410) of 50 pounds is for the tank/lines and hopefully at CG as the Water/Alcohol usable weight is 185 pounds - which I assume is at CG (best case for 'tipping' consideration as follows). Total moment arm BEYOND datum line and original Fully loaded CG is added 313 pounds (minimum) and possibly another 215 pounds (water tank+water/alcohol);
> 
> The CG for the P-39 is forward of the main gear. Correct? Why you ask? Lean back in a chair. What happens when the 'new CG' moves past the support legs? The Door Hinge Line(aft) and pilot seat back are at the approximate seat back for full internal load. ALL additional 'Engine mass' is aft of the Pilot seat and CG with V-1710-85.
> 
> ...


Put a wheel in the tail and use the front wheel to adjust CoG in flight, yet another win-win.

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## GrauGeist (Jul 28, 2021)

pbehn said:


> Put a wheel in the tail and use the front wheel to adjust CoG in flight, yet another win-win.


Wait...wait...I know this one!

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## pbehn (Jul 28, 2021)

GrauGeist said:


> Wait...wait...I know this one!
> 
> View attachment 634229


We are just a few hundred pages away from a real winner.


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## GregP (Jul 28, 2021)

By the way, the P-39 is not all that much smaller in the engine bay area than the P-63. But it IS a slight bit smaller and the Aux-stage Allison does not fit. The Aux supercharger would be up against a lateral brace and bulkhead (sort of a bulkhead, anyway). The fuselage is simply not big enough for the Aux S/C to fit inside, but it COULD be knocked out for a fit and the bulkhead COULD be moved. That would mess up the airflow around the area and the CG would be aft of the gear, but it COULD be done.

To fix these somewhat minor inconveniences, they made the P-63. If has very little in common with the P-39 except the general layout.

P-39:
http://www.aviastar.org/pictures/usa/bell_p-39.gif


P-63:
http://www.aviastar.org/pictures/usa/bell_p-63.gif

If you go look carefully at a 3-view of the P-39 and P-63, notice the placement of the wing.

In a P-39, the tip airfoil maximum thickness runs through the bulkhead line that is just behind the rear of the door. In the P-63, the tip airfoil maximum thickness runs through the middle of the exhaust manifolds. From the top view, the P-39 looks like the wing is almost exactly halfway along the fuselage, but it actually is located forward of halfway. From the top view of a P-63, the wing is definitely placed more rearward than on a P-39.

What happened is what Drgondog said, the CG moved aft with an aux-stage Allison installed, so the landing gear had to be moved aft. That's very hard to do without moving the wing, too. While it was somewhat POSSIBLE to move a few things around inside a P-39 and shoehorn in an aux-stage Allison, it was not really possible to move the wing attach point without major reconstruction. Hence, the P-63 design to accomplish all the changes required.

It may not seem obvious, but the Aux-stage supercharger, with shaft, comes in at between 220 and 250 pounds. Let's call it 200 pounds, just for the sake of discussion.

In the P-39, there is no structure where the Aux-stage would go if it could be fitted inside. The airplane was designed for 8 gs and an overload of 12 gs at some design weight. The Aux-stage sits behind the V-1710 power section a distance of some 2 feet or so. At 12 gs, we have about 2,400 pounds (200 x 12) cantlevered aft of the power section. To support that, you need a structure that also can withstand the stress of landing many times over with no maintenance (how many engine mount systems require regular maintenance?). A load-bearing structure doesn't come without some weight penalty. The middle structure is one of the primary differences between the P-39 and P-63 structure.

Why am I wasting my time doing this?

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## Peter Gunn (Jul 28, 2021)

GregP said:


> *SNIP*
> 
> Why am I wasting my time doing this?


Trust me, you ARE NOT wasting your time, I have read all your posts regarding this issue and have learned a lot from them, thank you.

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## vikingBerserker (Jul 28, 2021)

I'd like to suggest the mother of all threads which will easily carry us into the next century:

"Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained - Color pics For a Model I'm Building"


​

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## GregP (Jul 28, 2021)

I can give you P-39 and P-63 pics, but I just don't have time today. Will try my best before the weekend.

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## buffnut453 (Jul 28, 2021)

vikingBerserker said:


> I'd like to suggest the mother of all threads which will easily carry us into the next century:
> 
> "Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained - Color pics For a Model I'm Building"
> 
> ...



The one thread to rule them all? Smeagol wants the Precious!!!!

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## drgondog (Jul 28, 2021)

Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)


GregP said:


> I can give you P-39 and P-63 pics, but I just don't have time today. Will try my best before the weekend.


Greg - you did an excellent job of distilling a complex discussion to one that 'shall not be spoken or written of" MAY actually comprehend.

That said, the fallback after your gentle conversation will be to remind us that warm up, taxi, take off. form up and climb is not explicitly stated in the Op Manual - and 'let the combat radius discussion begin anew'...

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## FLYBOYJ (Jul 28, 2021)

GregP said:


> By the way, the P-39 is not all that much smaller in the engine bay area than the P-63. But it IS a slight bit smaller and the Aux-stage Allison does not fit. The Aux supercharger would be up against a lateral brace and bulkhead (sort of a bulkhead, anyway). The fuselage is simply not big enough for the Aux S/C to fit inside, but it COULD be knocked out for a fit and the bulkhead COULD be moved. That would mess up the airflow around the area and the CG would be aft of the gear, but it COULD be done.
> 
> To fix these somewhat minor inconveniences, they made the P-63. If has very little in common with the P-39 except the general layout.
> 
> ...


Greg - great information and despite what our narcissistic friend wants to believe or says I appreciate your inputs and efforts!

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## XBe02Drvr (Jul 28, 2021)

drgondog said:


> That said, the fallback after your gentle conversation will be to remind us that warm up, taxi, take off. form up and climb is not explicitly stated in the Op Manual - and 'let the combat radius discussion begin anew'...


Yay team! Too much fun to quit now. Records to beat and skies to conquer.

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## Airframes (Jul 28, 2021)

Yay, but verily, thy words fall on barren ground - oh, look, a groundhog !!!

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## pbehn (Jul 28, 2021)

On a serious note I found this on Joe Bauger's site Wartime Service of P-39 with USAAF
The 31st Fighter Group was provided with Airacobras in Southern England in August of 1942. Between August and October of 1942, the Group participated in missions against enemy targets in France. The Group suffered heavy losses in air-to-air combat against the Luftwaffe, and the 31st FG re-equipped with Spitfire Mk Vs.

I cant find any reference to the 31st fighter group using anything other than Spitfires in that period.

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## GregP (Jul 28, 2021)

I forgot to add some information about the “shoehorn an Aux-stage Allison into a P-39 post. The P-39Q-1 has an empty weight of 6,400 lbs and holds 87 gallons of internal fuel. Gross weight was 8,350 lbs. Per the manual. At 15,500 feet, at military power, it burns 138 US gallons of fuel per hour. The -35 engine was rated at 1,000 hp at 10,800 feet and 2,600 rpm.

A P-63A-1 has a gross weight of 8,410 lbs, holds 136 US gallons of internal fuel, and can carry a 64-gallons belly tank and/or a 75-galloins wing tank. They apparently needed more fuel than a P-39 did. The -93 engine was rated at 1,000 hp at 20,000 feet and 2,600 rpm.

The density of air at 10,800 feet is .001713 slugs / ft3​. The density of air at 20,000 feet is .001268 slugs / ft3​. To get the same air at 20,000 feet that you had at 10,800 feet (to make that 1,000 hp), you need an airflow of about 35% more at 20,000 feet than at 10,800 feet. So, you are looking at something like 35% more fuel flow except for the fact that the internal horsepower needed to drive 2 stages is way more than required to drive one stage. Let’s be conservative and say you need 75% more internal horsepower to drive 2 stages than to drive one stage.

If you go look at an engine book, you will find out that the fuel flow will materially increase. Yet another reason you could not modify a P-39 with a 2-stage engine ... there is not enough fuel to do anything except fight very close to the home airfield if you increase the fuel consumption by a substantial amount. The P-39 was already woefully short on range. Add in even a 35% higher fuel flow at 20,000 feet, never mind the extra due to internal power required to drive the aux stage, and you will not have enough range to be useful, even in a tactical situation, in a P-39 airframe, assuming you could move the wings aft as required.

We have yet another reason they designed the P-63! Added fuel, decent CG position, and the ability to be a fighter at 20,000 feet ... not just to fly there.

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## drgondog (Jul 28, 2021)

pbehn said:


> On a serious note I found this on Joe Bauger's site Wartime Service of P-39 with USAAF
> The 31st Fighter Group was provided with Airacobras in Southern England in August of 1942. Between August and October of 1942, the Group participated in missions against enemy targets in France. The Group suffered heavy losses in air-to-air combat against the Luftwaffe, and the 31st FG re-equipped with Spitfire Mk Vs.
> 
> I cant find any reference to the 31st fighter group using anything other than Spitfires in that period.


Two VCs 8-19-42 in P-39s, 307FS. Last before November 1942 in Spits/MTO. They participated in CAS during Dieppe raid.
Notable: first Mustang victory credit in ETO, last P-39 victory credit in ETO.

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## FLYBOYJ (Jul 28, 2021)

And before our friend begins a repetitive discussion about engine performance, may I suggest first reading this;






Especially Chapter 6


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## nuuumannn (Jul 28, 2021)

Peter Gunn said:


> VFR, IFR, IMC, VOR, VNE, ETC



IMC: I'm Mighty Confused, VOR: Very Original Response...

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## GregP (Jul 28, 2021)

IFR means, "I Follow Roads."
IMC means, "I Might Climb."
VNE means, "Very Nearly Extinct."
ETC means, "Extreme Technical Crap."

The best acronym I ever saw was FASOTRAGRULANT. 

I saw it on a sign at Patuxent River Naval Air Station. Even though it sounds like something you might eat in a Yugoslavian restaurant, it turned out to mean, "Fleet Avionics Squadron Operational Training Group Atlantic." Still, it sounds like a curse word from some long gone demented vernacular tongue ...

One of the better signs is coming into Reno Stead airport, "Fosdick Fullfillment." Not too sure what Fos if filling, but it made me laugh all the way to the gate on the way to the races.

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## SaparotRob (Jul 28, 2021)

ATP Adenosine Tri Phosphate

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## buffnut453 (Jul 28, 2021)

GregP said:


> IFR means, "I Follow Roads."
> IMC means, "I Might Climb."
> VNE means, "Very Nearly Extinct."
> ETC means, "Extreme Technical Crap."
> ...



Best military acronym I came across was at RAF Laarbruch in the early 1990s. One of the units stationed there was 2 Squadron flying recce Tornados. Like most HAS sites, the 2 Sqn dispersal had a range of hardened and non-hardened buildings, all painted dark green. There was flight ops, the engineering HQ etc...and then there was the TPOT (pronounced Tee-Pot). One visitor asked what TPOT stood for...and the no-kidding answer was That Place Over There. Essentially, it was a leftover building from the wet film recce days which didn't have a real purpose in the digital imagery age. I have to say TPOT fitted the bill rather well as the name for a nondescript, general purpose building

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## nuuumannn (Jul 28, 2021)

GregP said:


> IFR means, "I Follow Roads."


Or I Follow Railways...

In the hangar whenever something went wrong that happened as a result of something outside of nightshift, we blamed the COTOS. C**ts On The Other Shift...

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## nuuumannn (Jul 28, 2021)

pbehn said:


> a real winner.



Isn't that what the Expert's been telling us all along, but we're not listening?


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## GrauGeist (Jul 28, 2021)

The shop that I worked at for ages had several departments that all answered to the General Manager.
In his office were several paperwork trays that were for work orders, billing submissions, pending contracts and so on.
They were all labeled accordingly except for one at the bottom, which had a cryptic "JHCWTFN" label.
Curiosity got the better of me one day and I asked him what that was for, he stated that it was specifically for state (California) billing submissions that had been kicked back for reasons such as spelling errors, the text touched the line below the entry field (seriously) and so on. When the bill was returned, it meant regenerating the COM214, having it approved and resubmitted.

Aparently, the "JHCWTFN" was what he'd say when getting one of these refused billing submissions 

Translated: Jesus H. Christ, What The F*!#k Now???

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## DerAdlerIstGelandet (Jul 28, 2021)

P-39 Expert said:


> There is a very simple chart in the pilot's manual. And reading Edwards Park's book about the P-39 in NG. And AHT, Vees for Victory, and many other reference books.



The only thing you have proven is that you don’t know how to read and use these very simple charts.

Not insulting you, so don’t go there. Just pointing out facts.

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## fubar57 (Jul 28, 2021)

Took this photo of a P-39 down by the railroad tracks today

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## pbehn (Jul 28, 2021)

Here is a CoG I moved earlier


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## GregP (Jul 28, 2021)

Here is a P-39 restoration. Despite this thread, the P-39 is a very desirable warbird, and quite rare. If you're flying it VFR, it is down where its performance is good relative to other warbirds. Most of them don't spend a lot of time at 25,000 feet these days.




Seems like a good job of restoration. Hope to be showing one soon of a P-63!

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## Thumpalumpacus (Jul 28, 2021)

fubar57 said:


> Took this photo of a P-39 down by the railroad tracks today
> 
> View attachment 634396​



See? The goddamned thing's tail-heavy!

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## tyrodtom (Jul 28, 2021)

I read Nanette, Edwards Park's first book about 20 years ago, so I knew the local library had a copy, so I checked it out a reread it last night, and today. 
Not a big book, just 186 pages.

It describes their take off and joining up procedures.

P39 expert left out one important detail. A circle.

They did take off 2 by 2, then joined another 2 to form a flight.
Then the first 4 began a climbing circle, the other flights joined during the circling climb.
When everything was done right, they'd usually have all 4 flights joined by the time they'd completed one circle, and take a heading for their assigned mission.

A lot of the missions were done with just one flight, but joined other flights from another of the many fields around Port Moresby, P40s or P38s..

I'll quote Park from Nanette pg 18-19.
" But that wasn't the thing that was really wrong about the P-39 ( he's referring to it's tumbling habit ) The plane was simply underpowered for the kind of work it was supposed to do. It could not climb high enough or quickly enough, it could not go fast enough except in a dive, ( when it had a tendency to go too fast), it could not maneuver handily enough. It's controls were extremely delicate. The slightest hint of abruptness on the pilots part would be rewarded with a high speed stall .

Just the words of one man who flew the P-39

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## Thumpalumpacus (Jul 28, 2021)

pbehn said:


> Here is a CoG I moved earlier



The way this thread is going, your post here will be nose-ballast in six or seven thousand posts.


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## fubar57 (Jul 28, 2021)

Thumpalumpacus said:


> See? The goddamned thing's tail-heavy!


Tail view

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## GrauGeist (Jul 28, 2021)

tyrodtom said:


> I read Nanette, Edwards Park's first book about 20 years ago, so I knew the local library had a copy, so I checked it out a reread it last night, and today.
> Not a big book, just 186 pages.
> 
> It describes their take off and joining up procedures.
> ...


Great post!
Unfortunately, the Bell product authority discounts actual pilot accounts - except Chuck Yeager, who liked his trainer for some reason...


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## fubar57 (Jul 28, 2021)

GrauGeist said:


> Great post!
> Unfortunately, the Bell product authority discounts actual pilot accounts - except Chuck Yeager, who liked his trainer for some reason...


It did prepare him for the mildly adequate P-51

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## DerAdlerIstGelandet (Jul 28, 2021)

Found this P-39 yesterday at our camp in the Grand Tetons.

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## XBe02Drvr (Jul 28, 2021)

GregP said:


> The best acronym I ever saw was FASOTRAGRULANT.


That's the command I worked for 3 1/2 years, except I was in the Key West detachment. Back in the day it handled all the training aids, from Operational Flight Trainers/Weapons System Trainers (OFT/WSTs, how's that for an acronym?) on down to tape recorders, film projectors and film libraries and everything in between, with detachments at each NAS on or near the east coast. FASOTRAGRULANT dets were manned by TDs (TraDevMen [and women!]), AKA "Toy Doctors" or "Turd Dunkers", depending on how reliably their equipment was performing on any given day. I must confess my ancient vaccum tube analog computer radar trainer kept me in Turd Dunker territory much of the time. Seventeen cabinets full of servos and tube type op amps that had a penchant for only burning out the rare and hard to get tubes.
Sometime in the late 80s, the Navy elected to abolish the TD rate and let the work out to contract, as the technology was getting too advanced to get recruits up to speed before their enlistments ran out, and the career petty officers were leaving to work for the flight sim companies and the airlines.
TDs were resented by the seagoing Navy, as nearly all the billets were ashore, the only shipboard TDs being the PLAT system techs on carriers. When the rate was abolished, I'm told TDs that wanted to stay in the service were converted to ICs (Interior Communication men) and banished to the black shoe Navy to spend the rest of their careers at sea. (So much for highfalutin beachbound airedales!) Oh well, it was a heck of a gig while it lasted.
I understand FASOTRAGRULANT has had its first "A" changed from "Aviation" to "Avionics" as Greg said and now the dets are advanced schools for Com/Nav, airborne ASW, and airborne Radar/Fire Control techs who will be going where civilian tech reps can't.

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## GrauGeist (Jul 28, 2021)

fubar57 said:


> It did prepare him for the mildly adequate P-51


My guess would be yes, since the P-51 didn't have nose armor

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## buffnut453 (Jul 29, 2021)

tyrodtom said:


> I read Nanette, Edwards Park's first book about 20 years ago, so I knew the local library had a copy, so I checked it out a reread it last night, and today.
> Not a big book, just 186 pages.
> 
> It describes their take off and joining up procedures.
> ...



What? So you mean the reference material was selectively cherry-picked? I'm shocked...SHOCKED, I tell you!

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## GrauGeist (Jul 29, 2021)

buffnut453 said:


> What? So you mean the reference material was selectively cherry-picked? I'm shocked...SHOCKED, I tell you!


Oh the humanity!!


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## Thumpalumpacus (Jul 29, 2021)



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## buffnut453 (Jul 29, 2021)

Again, the comedy value of this thread just keeps on giving and giving. 

People had pointed out numerous times that escorting fighters would have to circle the base to form up. The Expert then cites a source that seems to contradict it...but he misses out the key part of the story where the source explicitly states they were flying a circle. 

I've seen some impressive efforts at muddying the waters in debates on this forum, but that one really does take first prize.

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## XBe02Drvr (Jul 29, 2021)

GregP said:


> Here is a P-39 restoration. Despite this thread, the P-39 is a very desirable warbird, and quite rare. If you're flying it VFR, it is down where its performance is good relative to other warbirds. Most of them don't spend a lot of time at 25,000 feet these days.
> 
> 
> 
> ...



That forward gearbox sure does sing! I've seen P39s a couple of times at airshows, but never close enough to hear that.

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## Ascent (Jul 29, 2021)

Back when i was an engine tech in the RAF (A sootie to those in the know) the maintenance part of the squadron was split into two, A and B shift (pretty standard). Those of us on B-Shift called ourselves PART, Post A-Shift Recovery Team, because we were always having to sort out the mistakes they made.

I'm sure they felt the same about us.

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## Stig1207 (Jul 29, 2021)

pbehn said:


> On a serious note I found this on Joe Bauger's site Wartime Service of P-39 with USAAF
> The 31st Fighter Group was provided with Airacobras in Southern England in August of 1942. Between August and October of 1942, the Group participated in missions against enemy targets in France. The Group suffered heavy losses in air-to-air combat against the Luftwaffe, and the 31st FG re-equipped with Spitfire Mk Vs.
> 
> I cant find any reference to the 31st fighter group using anything other than Spitfires in that period.



Joe must have got in a muddle with this one, according to this site 31st FG the unit travelled by sea to the UK without planes and converted to Spitfires. Their only claims / losses were on the Dieppe raid.


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## pbehn (Jul 29, 2021)

Stig1207 said:


> Joe must have got in a muddle with this one, according to this site 31st FG the unit travelled by sea to the UK without planes and converted to Spitfires. Their only claims / losses were on the Dieppe raid.


If you read Drgondog's post 3356 on this thread he quotes actions by P-39s and a P-39 was claimed by A LW pilot. That site was one of the ones I was alluding to when I asked the question.


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## pbehn (Jul 29, 2021)

Stig1207 said:


> Joe must have got in a muddle with this one, according to this site 31st FG the unit travelled by sea to the UK without planes and converted to Spitfires. Their only claims / losses were on the Dieppe raid.


With reference to the links below.

It is plausible that a pilot may think a plane with American markings was a P-39. But Hermichen was an ace pilot, by August 1942 he will have known what a Spitfire looked like as much as anyone in the air.








The National Interest: Blog







nationalinterest.org




German intelligence apparently did not realize that the Americans were flying Spitfires. When Oberleutnant Rolf Hermichen of Jagdgeschwader 26 shot down a fighter marked with the U.S. insignia, he claimed a P-39 Airacobra destroyed. No P-39s were in the air over Dieppe.


Focke-Wulf 190s Over Dieppe


Rolf Hermichen of 3./J.G. 26 claimed destruction of a P-39 at 11:38 (a case of mis-identification).

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## Shortround6 (Jul 29, 2021)

According to AHT (and the unit histories) the 81st fighter group and the 350th fighter group were in England in late 1942 with P-39s.

The Histories do not entirely agree with AHT (several sentences) but it seems that both units were at least partially equipped with ex-RAF aircraft still in the crates that had not been sent to Russia (or returned due to convoy turning back) The 350th was at least partially manned by US pilots from the Eagle squadrons and was activated in the UK.
Perhaps they did see some combat, none is noted in the brief unit histories I read. but essentially they trained in England for the forthcoming NA invasion. Due to the English winter weather some of the 350th pilots got around 20 hours time in the P-39s before undertaking the ferry flight to French Morocco. The two groups loose 15 planes on the ferry flight, many interned in Portugal. One may have been shot down on the way.

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## drgondog (Jul 29, 2021)

tyrodtom said:


> I read Nanette, Edwards Park's first book about 20 years ago, so I knew the local library had a copy, so I checked it out a reread it last night, and today.
> Not a big book, just 186 pages.
> 
> It describes their take off and joining up procedures.
> ...


Further to the point - an 8th AF escort mission required multiplying the above by 3X to get three full squadrons (Plus usually 2 spares per squadron, and leaving out the fuel consumption of the last squadron as they sit 'warming up' prior to taxiing to the active.

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## drgondog (Jul 29, 2021)

Stig1207 said:


> Joe must have got in a muddle with this one, according to this site 31st FG the unit travelled by sea to the UK without planes and converted to Spitfires. Their only claims / losses were on the Dieppe raid.


Actually, the universe is at odds with itself re: P-39 actually being flown by 31st FG in combat. The 8th AF VC detail Victory credits have 2 P-39 victories on 19 August, 1942. Frank Olynyk (whom I trust most of historians) has Spit V and Roger Freeman has Spitfire assigned to 31st upon arrival in Britain. JG 26 Hermichen stated Aircobra for August 19th - amidst another victory claim for a Spitfire in the same area around Dieppe. 

I relied on 8th AF and JG 26 as primary source but have no dog in this hunt as I have never been certain. My logic is that 350th FG conclusively were assigned P-400 that RAF did not want. ALL my sources agree that, and that it was briefly assigned to 8th AF. My father's last USAF job was Dpty COS - Missiles Div, ADC to M.Gen Sandy McCorkle - former CO of 31st. McCorkle was NOT with 31st in England, joined in 1943 as CO. That said, he 'remembered' that 1st flew Aircobra's in England before conversion to Spits. 

If so, where did they go - the 350th FG?

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## GrauGeist (Jul 29, 2021)

XBe02Drvr said:


> That forward gearbox sure does sing! I've seen P39s a couple of times at airshows, but never close enough to hear that.


I've seen cutaway drawings of the gearbox but don't recall if the gears are straight-cut or helical, but it sure sounds alot like a Pete Jackson gear drive for a small block Chevy!

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## tyrodtom (Jul 29, 2021)

buffnut453 said:


> Again, the comedy value of this thread just keeps on giving and giving.
> 
> People had pointed out numerous times that escorting fighters would have to circle the base to form up. The Expert then cites a source that seems to contradict it...but he misses out the key part of the story where the source explicitly states they were flying a circle.
> 
> I've seen some impressive efforts at muddying the waters in debates on this forum, but that one really does take first prize.


And still what Park did write was just the bare minimum , like I said earlier, dumbed down for the general public.

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## FLYBOYJ (Jul 29, 2021)

tyrodtom said:


> And still what Park did write was just the bare minimum , like I said earlier, *dumbed down for the general public.*


Or for non-pilots who read the manual












I think it's absolutely disgraceful when someone cherry picks to prove a point, especially on this forum. Great job Tom on calling this one out!

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## pbehn (Jul 29, 2021)

buffnut453 said:


> Again, the comedy value of this thread just keeps on giving and giving.
> 
> People had pointed out numerous times that escorting fighters would have to circle the base to form up. The Expert then cites a source that seems to contradict it...but he misses out the key part of the story where the source explicitly states they were flying a circle.
> 
> I've seen some impressive efforts at muddying the waters in debates on this forum, but that one really does take first prize.


The novel suggested method would result in an angry looking formation of 50 aircraft in pairs, 25 miles across and 10,000ft separation in altitude from one side to the other.

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## GregP (Jul 29, 2021)

Regarding the weight of the Allison Aux-Stage engine, our expert has been missing a basic point:

The E-series engines all had a drive gear on the front of the power section to interface with a driveshaft while the F-series engines all had a nose case and a propeller shaft so the aircraft could mount a propeller instead of run a driveshaft.

The V-1710-35 (E4 single-stage engine), as installed in the P-39 weighed in at 1,375 pounds. It was rated at 1,150 hp/3,000 rpm / 11,200 feet Military and 1,000 hp / 2,600 rpm / 10,800 feet max continuous.

The V-1710-93 (E11 2-stage engine with Auxiliary supercharger), as installed in the P-63A and C weighed in at 1,620 pounds. It was rated at 1,325 hp / 3,000 rpm / S.L. Military and 1,000 hp / 2,600 rpm / 20,000 feet max continuous.

The weight difference was 245 pounds. What our expert fails to comprehend is that the single stage engine had a carburetor and auxiliary section attached to the power section which was self-contained and had everything needed to run the engine. Carb, fuel lines, fuel diffuser, etc. The Aux-stage engine had all the items needed to run the engine moved to the Aux stage … like the carb, fuel lines, fuel diffuser, etc. The only thing remaining on the power section was an impeller and a much smaller impeller housing since the carb and everything else was mounted to the aux stage.

The weight of the aux stage was NOT the difference between the -35 and the -39. It was heavier because most of the former single stage parts were mounted on the aux stage, and the power section had an impeller mounted to it that was substantially lighter than the self-contained normal single-stage impeller section.

Next time I get over to Joe Yancey’s shop, I’ll ask about the weight, but I’m pretty sure it was around 275 pounds.

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## BiffF15 (Jul 29, 2021)

pbehn said:


> The novel suggested method would result in an angry looking formation of 50 aircraft in pairs, 25 miles across and 10,000ft separation in altitude from one side to the other.


In the movie Heartbreak Ridge, Clint Eastwoods character Gunny Highway said it best, when asked by the CO what the hell was going on, to which he replied, “It’s a clusterf—k sir!”.

Arriving at a fight in single file allows the enemy to bring a mass formation to bear against your line. Not a winning move.

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## Stig1207 (Jul 29, 2021)

drgondog said:


> Actually, the universe is at odds with itself re: P-39 actually being flown by 31st FG in combat. The 8th AF VC detail Victory credits have 2 P-39 victories on 19 August, 1942. Frank Olynyk (whom I trust most of historians) has Spit V and Roger Freeman has Spitfire assigned to 31st upon arrival in Britain. JG 26 Hermichen stated Aircobra for August 19th - amidst another victory claim for a Spitfire in the same area around Dieppe.
> 
> I relied on 8th AF and JG 26 as primary source but have no dog in this hunt as I have never been certain. My logic is that 350th FG conclusively were assigned P-400 that RAF did not want. ALL my sources agree that, and that it was briefly assigned to 8th AF. My father's last USAF job was Dpty COS - Missiles Div, ADC to M.Gen Sandy McCorkle - former CO of 31st. McCorkle was NOT with 31st in England, joined in 1943 as CO. That said, he 'remembered' that 1st flew Aircobra's in England before conversion to Spits.
> 
> If so, where did they go - the 350th FG?



I have no dog (or groundhog) in this either; but something's not right and I think that Joe Baugher got mixed up with the the 31st Pursuit Group (39th, 40th, 41st fs) that flew P-39's in the States.


> Redesignated 31st Fighter Group in May 1942. Moved to England, May-June 1942. Assigned to Eighth Air Force and equipped with Spitfires. Entered combat in August 1942. Supported a raid made by Canadian, British, American, and French forces at Dieppe on 19 August. Escorted bombers and flew patrol and diversionary missions until Oct.



The squadrons are also redesignated: 307th, 308th, 309th.

Edited to correct the squadrons for the 31st FG.

31st Fighter Group in World War II - Honor Roll Project

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## drgondog (Jul 29, 2021)

Stig1207 said:


> I have no dog (or groundhog) in this either; but something's not right and I think that Joe Baugher got mixed up with the the 31st Pursuit Group (39th, 40th, 41st fs) that flew P-39's in the States.
> 
> 
> The squadrons are also redesignated: 334th, 335th, 336th.
> ...


Stig, the Eagle Squadrons were so designated (4th FG). 

The 31st FG had 307,308 and 309FS, all organized into 31st FG in May 1942. You can find the 39th, 40th and 41st in the 35th FG. My father commanded the 35th in Japan - we were at Johnson AFB. Jeff Ethell's father Irv was a 39th FS CO during our time there.

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## vikingBerserker (Jul 29, 2021)

Here is an American Southern P-39

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## pbehn (Jul 29, 2021)

Rolf Gunther Hermichen was in the LW at the start of the war, served in the French campaign, The Battle of Britain, on the eastern front before returning to France in 1942. He claimed a Hurricane at the end of July which was a Hurricane, a Spitfire on the 18 August, another Spitfire on the 19 August plus another he claimed as an Airacobra. This was his 18th claim 5 previous claims for Spitfires. He must have had reasons to think it was a P-39.



Focke-Wulf 190s Over Dieppe


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## buffnut453 (Jul 29, 2021)

vikingBerserker said:


> Here is an American Southern P-39
> 
> View attachment 634547



Someone's had too many Big Macs, haven't they? Or is it just the nose armour and gas heater that make him look fat?

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## pbehn (Jul 29, 2021)

buffnut453 said:


> Someone's had too many Big Macs, haven't they? Or is it just the nose armour and gas heater that make him look fat?


Hes eaten such a big supercharger hes fallen on his tail, as predicted.

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## FLYBOYJ (Jul 29, 2021)

pbehn said:


> Rolf Gunther Hermichen was in the LW at the start of the war, served in the French campaign, The Battle of Britain, on the eastern front before returning to France in 1942. He claimed a Hurricane at the end of July which was a Hurricane, a Spitfire on the 18 August, another Spitfire on the 19 August plus another he claimed as an Airacobra. This was his 18th claim 5 previous claims for Spitfires. He must have had reasons to think it was a P-39.
> 
> 
> 
> Focke-Wulf 190s Over Dieppe


From a quick internet scan it seems the P-39s that were operated in the UK carried similar camouflage and colors as the Spitfire Mk Vs flown over Dieppe. Am I wrong?


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## pbehn (Jul 29, 2021)

FLYBOYJ said:


> From a quick internet scan it seems the P-39s that were operated in the UK carried similar camouflage and colors as the Spitfire Mk Vs flown over Dieppe. Am I wrong?


As far as I know yes, but so did all RAF planes including the Mustang I. The Spitfire Vs operated by US forces at the time simply had a US star painted over the RAF roundel. These subjects have been modelled frequently on the forum, to me they look a little curious just because they are Spitfires with US markings, they dont look like P-39s. Spitfires and Hurricanes with a Russian red star also dont look like P-39s.

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## fubar57 (Jul 29, 2021)

vikingBerserker said:


> Here is an American Southern P-39
> 
> View attachment 634547


David. I wish I could give Bacon, Winner and Funny

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## pbehn (Jul 29, 2021)

BiffF15 said:


> In the movie Heartbreak Ridge, Clint Eastwoods character Gunny Highway said it best, when asked by the CO what the hell was going on, to which he replied, “It’s a clusterf—k sir!”.
> 
> Arriving at a fight in single file allows the enemy to bring a mass formation to bear against your line. Not a winning move.


This was thought about, by making a cunning 90 degree turn after take off your formation is line abreast, looking for a 25 mile wide gap in the coastal defences to take on the enemy in twos. Some would say it is not a formation at all, just a lot of pairs of aircraft in the air at the same time who's only option when meeting any opposition is to turn back.


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## FLYBOYJ (Jul 29, 2021)

pbehn said:


> As far as I know yes, but so did all RAF planes including the Mustang I. The Spitfire Vs operated by US forces at the time simply had a US star painted over the RAF roundel. These subjects have been modelled frequently on the forum, to me they look a little curious just because they are Spitfires with US markings, they dont look like P-39s. Spitfires and Hurricanes with a Russian red star also dont look like P-39s.
> 
> 
> 
> View attachment 634555


Just thinking that LW intelligence might have briefed that P-39s were in England and in the heat of battle a Spitfire looked like a P-39

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## BiffF15 (Jul 29, 2021)

FLYBOYJ said:


> Just thinking that LW intelligence might have briefed that P-39s were in England and in the heat of battle a Spitfire looked like a P-39



It’s easy to get a Visual Identification (VID) incorrect. I have seen guys of all experience levels get it wrong, and that is in training with nothing real being shot at you.

In F-15 school the intel officer was teaching us aircraft recognition, and he got it wrong and they were his slides. He didn’t take having his error pointed out very well either.

Cheers,
Biff

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## P-39 Expert (Jul 29, 2021)

GregP said:


> By the way, the P-39 is not all that much smaller in the engine bay area than the P-63. But it IS a slight bit smaller and the Aux-stage Allison does not fit. The Aux supercharger would be up against a lateral brace and bulkhead (sort of a bulkhead, anyway). The fuselage is simply not big enough for the Aux S/C to fit inside, but it COULD be knocked out for a fit and the bulkhead COULD be moved. That would mess up the airflow around the area and the CG would be aft of the gear, but it COULD be done.


As I have shown many times with construction drawings of both planes, the engine compartments are exactly the same length. And the auxiliary stage was installed in a P-39D fuselage to be the P-39E.


GregP said:


> To fix these somewhat minor inconveniences, they made the P-63. If has very little in common with the P-39 except the general layout.
> 
> P-39:
> http://www.aviastar.org/pictures/usa/bell_p-39.gif
> ...


P-63 was a new design with the aft fuselage behind the engine compartment lengthened. Wing had to be moved back to balance.


GregP said:


> It may not seem obvious, but the Aux-stage supercharger, with shaft, comes in at between 220 and 250 pounds. Let's call it 200 pounds, just for the sake of discussion.


Proof? AHT lists the weights as 1435lb for the P-39D-2 and 1620lbs for the P-63A, a difference of 185lb. These were both production airplanes. The coolant expansion tank would be moved forward to about the CG and the carb should have been on the engine stage like the other Allison production models, providing an extra 3000' critical altitude. Neither of those items weighed much but moving both forward would have helped the CG situation. But mainly CG would have been restored by using a larger (heavier) four blade propeller to handle the extra HP at high altitude.


GregP said:


> In the P-39, there is no structure where the Aux-stage would go if it could be fitted inside. The airplane was designed for 8 gs and an overload of 12 gs at some design weight. The Aux-stage sits behind the V-1710 power section a distance of some 2 feet or so. At 12 gs, we have about 2,400 pounds (200 x 12) cantlevered aft of the power section. To support that, you need a structure that also can withstand the stress of landing many times over with no maintenance (how many engine mount systems require regular maintenance?). A load-bearing structure doesn't come without some weight penalty. The middle structure is one of the primary differences between the P-39 and P-63 structure.


It certainly would fit inside, it was exactly the same size on both planes. And the structure to withstand the stress was already there. The twin longitudinal beams that made up the fuselage structure provided a very robust mount for the propeller reduction gear, nose landing gear, nose armament, cockpit, and engine compartment which would include the aux stage SC, as it did on the P-63. This structure also provided for attachment of the wing to the fuselage. The tail empennage was of conventional construction.


GregP said:


> Why am I wasting my time doing this?


I don't know. I make one post and get 10 replies and then everyone blames me for the length of the thread.

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## BiffF15 (Jul 29, 2021)

P-39 Expert said:


> As I have shown many times with construction drawings of both planes, the engine compartments are exactly the same length. And the auxiliary stage was installed in a P-39D fuselage to be the P-39E.
> 
> P-63 was a new design with the aft fuselage behind the engine compartment lengthened. Wing had to be moved back to balance.
> 
> ...



P-39Expert,

You get ten replies per posting because the guys are deconstructing your comments and repeatedly proving some of what you post as wrong. I remember the engine bay discussion from before, yet here we are again. 

You are under the belief that you have discovered something that no one in WW2 who actually built, flew or maintained the plane knew. In reality you haven’t, and guys go to exaggerated lengths, and very nicely for the most part, to explain where you got off the correct path. Alas, to no avail.

Good luck,
Biff

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## Glider (Jul 29, 2021)

P-39 Expert said:


> As I have shown many times with construction drawings of both planes, the engine compartments are exactly the same length. And the auxiliary stage was installed in a P-39D fuselage to be the P-39E.
> 
> P-63 was a new design with the aft fuselage behind the engine compartment lengthened. Wing had to be moved back to balance.
> 
> ...


Stuff this lot as the facts as you state them are anything but. Personally I would like your reasons for so deliberately being very selective about quotes from books which you claimed were providing slam dunk evidence proving you belief about how P39 units formed up. 

When the unaltered document shows that the 
1) P39 was to slow in a straight line, 
2) Too slow in a climb, 
3) Couldn't manoeuvre, 
4) Tended to overspeed in a dive
5) Everyone had to circle until the unit formed up

I don't really expect a reply let alone an explanation, but it highlights the lengths you will go to support your misguided belief.

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## P-39 Expert (Jul 29, 2021)

tyrodtom said:


> I read Nanette, Edwards Park's first book about 20 years ago, so I knew the local library had a copy, so I checked it out a reread it last night, and today.
> Not a big book, just 186 pages.
> 
> It describes their take off and joining up procedures.
> ...


Nanette was fiction, Angels Twenty was fact based on the same location and time period. From the book: "We (two planes) started our takeoff run before the first element (two planes) was off the ground. They began their turn, a wide gentle swing. Wingman and I were able to turn easily inside them and so put the flight in proper formation. By the time we were on course for the coordinate Blue Flight was with us, all in position." That was only two flights (eight planes, half a squadron), but the process was very quick and simple.


tyrodtom said:


> A lot of the missions were done with just one flight, but joined other flights from another of the many fields around Port Moresby, P40s or P38s..
> 
> I'll quote Park from Nanette pg 18-19.
> " But that wasn't the thing that was really wrong about the P-39 ( he's referring to it's tumbling habit ) The plane was simply underpowered for the kind of work it was supposed to do. It could not climb high enough or quickly enough, it could not go fast enough except in a dive, ( when it had a tendency to go too fast), it could not maneuver handily enough. It's controls were extremely delicate. The slightest hint of abruptness on the pilots part would be rewarded with a high speed stall .


Park was no friend of the P-39, but in the other book he made it clear that the biggest fault was too much weight, coming mainly from the wing guns and too much armor plate. In neither book did he say that the plane was difficult or dangerous to fly and was particularly easy to take off and land.


tyrodtom said:


> Just the words of one man who flew the P-39


I thoroughly enjoyed both books, finding them at times laugh out loud funny at the situations he and his squadron mates found themselves in both in combat and on leave. I thought it was an accurate portrayal of day to day life on a forward base in NG during a time early on when the AAF was on the defensive. I recommend both books as very entertaining for someone interested in WW2 aviation.


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## SaparotRob (Jul 29, 2021)

pbehn said:


> As far as I know yes, but so did all RAF planes including the Mustang I. The Spitfire Vs operated by US forces at the time simply had a US star painted over the RAF roundel. These subjects have been modelled frequently on the forum, to me they look a little curious just because they are Spitfires with US markings, they dont look like P-39s. Spitfires and Hurricanes with a Russian red star also dont look like P-39s.
> 
> 
> 
> View attachment 634555


Maybe just a quick glance during combat when things are happening fast? Star or roundel catches the eye and brain lables it a different plane.

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## Glider (Jul 29, 2021)

P-39 Expert said:


> Park was no friend of the P-39, but in the other book he made it clear that the biggest fault was too much weight, coming mainly from the wing guns and too much armor plate. In neither book did he say that the plane was difficult or dangerous to fly and was particularly easy to take off and land.
> 
> _I would be interested to know where in the book it states that the additional weight came from having wing guns and too much armour. Its a long time since I read the book but nowhere do I remember it being specific about guns and armour. Just that the P39 weighed too much_

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## pbehn (Jul 29, 2021)

SaparotRob said:


> Maybe just a quick glance during combat when things are happening fast? Star or roundel catches the eye and brain lables it a different plane.





FLYBOYJ said:


> Just thinking that LW intelligence might have briefed that P-39s were in England and in the heat of battle a Spitfire looked like a P-39





BiffF15 said:


> It’s easy to get a Visual Identification (VID) incorrect. I have seen guys of all experience levels get it wrong, and that is in training with nothing real being shot at you.
> 
> In F-15 school the intel officer was teaching us aircraft recognition, and he got it wrong and they were his slides. He didn’t take having his error pointed out very well either.
> 
> ...


Ive put all three posts together because they cover the same basic subject

From other posts, it is perfectly possible that P-39s were available in UK and were due to lease lend and other contractual wrangles the property of the USA by the time 601 squadron stopped using them in March 1942. Also from other posts there is some anecdotal evidence that P-39s were used for CAS at Dieppe.

I agree that misidentification is quite easy, from the link I posted Hermichen did mis identify some aircraft, like Typhoons for P-47s, and I know it isnt easy, the Typhoon was confused with an Fw190 so often they put stripes on it. However advising the LW pilots that P-39s were in the area may have planted an idea in a pilots head, but only one reported shooting down a P-39, and it would only be done if P-39s were there, Hermichen would certainly know what a P-39 looked like in August 1942. I dont have a side in the argument, I just thought it was an interesting contradiction Joe Baugher and Bill dont write things on a whim. And in any case it is a distraction from the normal groundhoggery. The various ins and outs of it would make a great Agatha Christie plot.

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## pbehn (Jul 29, 2021)

BiffF15 said:


> P-39Expert,
> 
> You get ten replies per posting


And he is the lucky one, because I get one reply from ten posts from our expert, like most others on the forum, my posts are completely ignored and the same crap dragged up after a suitable period of internet mourning, it seems that if you put BS on one side for a period of time it starts smelling all fresh and new again, like mown grass.

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## BiffF15 (Jul 29, 2021)

pbehn said:


> And he is the lucky one, because I get one reply from ten posts from our expert, like most others on the forum, my posts are completely ignored and the same crap dragged up after a suitable period of internet mourning, it seems that if you put BS on one side for a period of time it starts smelling all fresh and new again, like mown grass.


He doesn’t answer my posts either.


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## Milosh (Jul 29, 2021)

The Brits did say they encountered He100s.

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## FLYBOYJ (Jul 29, 2021)

Milosh said:


> The Brits did say they encountered He100s.


I think Robert Johnson claimed an Me209

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## pbehn (Jul 29, 2021)

BiffF15 said:


> He doesn’t answer my posts either.


Dont take it personally, you are among a several hundred "Joe Pilots" whose written reports are discounted, as an interested poster I am miles behind you, but you are in great company, ahead of you are Dowding and Park who also didnt have a clue, I am reliably informed.

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## buffnut453 (Jul 29, 2021)

P-39 Expert said:


> As I have shown many times with construction drawings of both planes, the engine compartments are exactly the same length.



Please explain the term "construction drawings". I'm familiar with: Detail Drawings, which depict an individual part; Assembly Drawings, which describe an object made up of two or more parts; Installation Drawings, which shows a part or assembly in its installed location, and; Sectional View Drawings, which cut away part of an object to show the shape and construction along the cutting plane. There are also schematics which describe, at some degree of abstraction, systems within an aircraft. So what are "construction drawings"?

I presume you're referring to the "drawings" you cited in this post: XP-39 II - The Groundhog Day Thread. Those are Installation Drawings showing the station positions in the airframe. They ONLY show the distance between stations. They DO NOT show the height or width dimensions. 

Just because compartments are "exactly the same length" does not mean that a 3-dimensional object will fit in that space. You need distances across length, width and height...and you also need to reflect any changes to those measurements to see if the physical space is sufficient...and, even then, there may be issues fitting an assembly into the available space because other parts or assemblies might get in the way.

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## pbehn (Jul 29, 2021)

P-39 Expert said:


> Park was no friend of the P-39, but in the other book he made it clear that the biggest fault was too much weight, coming mainly from the wing guns and too much armor plate. In neither book did he say that the plane was difficult or dangerous to fly and was particularly easy to take off and land.


And so removing armour and wing guns is the basis of all your 1,750 posts? What about the input of the Russians who wanted more armour in certain places to stay alive, which is quite important I am told.

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## GrauGeist (Jul 29, 2021)

buffnut453 said:


> Please explain the term "construction drawings". I'm familiar with: Detail Drawings, which depict an individual part; Assembly Drawings, which describe an object made up of two or more parts; Installation Drawings, which shows a part or assembly in its installed location, and; Sectional View Drawings, which cut away part of an object to show the shape and construction along the cutting plane. There are also schematics which describe, at some degree of abstraction, systems within an aircraft. So what are "construction drawings"?
> 
> I presume you're referring to the "drawings" you cited in this post: XP-39 II - The Groundhog Day Thread. Those are Installation Drawings showing the station positions in the airframe. They ONLY show the distance between stations. They DO NOT show the height or width dimensions.
> 
> Just because compartments are "exactly the same length" does not mean that a 3-dimensional object will fit in that space. You need distances across length, width and height...and you also need to reflect any changes to those measurements to see if the physical space is sufficient...and, even then, there may be issues fitting an assembly into the available space because other parts or assemblies might get in the way.


He's read manuals and held up "drawings" for comparison.
He's also observed a static P-39 display at a museum.

In light of these details, it's obvious that we're dealing with a highly qualified internet Aerospace Engineer...

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## FLYBOYJ (Jul 29, 2021)

buffnut453 said:


> Please explain the term "construction drawings". I'm familiar with: Detail Drawings, which depict an individual part; Assembly Drawings, which describe an object made up of two or more parts; Installation Drawings, which shows a part or assembly in its installed location, and; Sectional View Drawings, which cut away part of an object to show the shape and construction along the cutting plane. There are also schematics which describe, at some degree of abstraction, systems within an aircraft. So what are "construction drawings"?


"Construction drawings" A new one...

In balance
combat power
tail cone
landing reserve

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## pbehn (Jul 29, 2021)

FLYBOYJ said:


> "Construction drawings" A new one...
> 
> In balance
> combat power
> ...


In my work I was concerned with refineries and oil installations (at times). I frequently heard the expression "approved for construction" or "issued for construction" with regard to drawings, but this is a different branch of engineering. The important drawings in this conversation would be what I heard being discussed as the "as built" drawings.

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## FLYBOYJ (Jul 29, 2021)

buffnut453 said:


> Please explain the term "construction drawings". I'm familiar with: Detail Drawings, which depict an individual part; Assembly Drawings, which describe an object made up of two or more parts; Installation Drawings, which shows a part or assembly in its installed location, and; Sectional View Drawings, which cut away part of an object to show the shape and construction along the cutting plane. There are also schematics which describe, at some degree of abstraction, systems within an aircraft. So what are "construction drawings"?
> 
> I presume you're referring to the "drawings" you cited in this post: XP-39 II - The Groundhog Day Thread. Those are Installation Drawings showing the station positions in the airframe. They ONLY show the distance between stations. They DO NOT show the height or width dimensions.
> 
> Just because compartments are "exactly the same length" does not mean that a 3-dimensional object will fit in that space. You need distances across length, width and height...and you also need to reflect any changes to those measurements to see if the physical space is sufficient...and, even then, there may be issues fitting an assembly into the available space because other parts or assemblies might get in the way.


At Lockheed we also had "Production Illustrations" (PIs) that had a 3-D view of an installation that might not have been made clear on installation drawings. They were really helpful for wire harness routing within a confined area.

Another aspect is the production tooling which is the actual linchpin in aircraft constriction. In my experience in building up sub assemblies, the tooling dictated the final outcome and there was always a war in ensuring the tooling matched assembly or installation drawings. 

Funny thing too was Lockheed was late in introducing GDT.

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## FLYBOYJ (Jul 29, 2021)

pbehn said:


> In my work I was concerned with refineries and oil installations (at times). I frequently heard the expression "approved for construction" or "issued for construction" with regard to drawings, but this is a different branch of engineering. The important drawings in this conversation would be what I heard being discussed as the* "as built" drawings.*


First time I heard that term is when I was assigned to Canadair as a QA Rep on the CP-140 program many years ago.

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## GrauGeist (Jul 29, 2021)

When I was outfitting Fire apparatus, we'd submit a 3D illustration of the proposed wire routing to the equipment called a "Final Stage Illustration" during meetings with the agency.

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## pbehn (Jul 29, 2021)

FLYBOYJ said:


> First time I heard that term is when I was assigned to Canadair as a QA Rep on the CP-140 program many years ago.


All nations and industries are different. Sometimes there were various solutions proposed to the client as drawings for approval, at other times many solutions were proposed and fabricated on site (with no client involvement) and the solution to the problem was included in the "as built" drawing submitted to the client. A lot depended on the scope and involvement of the end client, in the oil industry, the end client frequently wants to off load as much responsibility as possible, in case something goes wrong. In WW2 aviation it was usually but not always different.

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## DerAdlerIstGelandet (Jul 29, 2021)

BiffF15 said:


> He doesn’t answer my posts either.



That is why I stopped making serious posts to him to begin with.

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## DerAdlerIstGelandet (Jul 29, 2021)

Wait, I was serious when I said the only thing he has proven is that he cannot read or use simple charts.

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## Thumpalumpacus (Jul 29, 2021)

He clearly only replies when he thinks it offers him an opportunity to advance his agenda.

I've been dogpiled before (elsewhere, obvs) , and while it's hard, it's doable, by collating posts and answering multiples with one reply. 

 P-39 Expert
's problem seems to be that he's making so many questionable claims and facing pushback from so many different angles that he's tying himself into knots trying to 1) answer an objection and 2) do so in such a manner that he doesn't undercut another answer of his to another objection.

Hence appealing to different variants of the P-39, or even appealing to the P-63, and hoping no one notices that he's engaged in overlarge equivocation. Or, as I have it saved as a smiley:

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## GregP (Jul 29, 2021)

P-39 Expert said:


> As I have shown many times with construction drawings of both planes, the engine compartments are exactly the same length. And the auxiliary stage was installed in a P-39D fuselage to be the P-39E.
> 
> P-63 was a new design with the aft fuselage behind the engine compartment lengthened. Wing had to be moved back to balance.
> 
> ...



Hey P-39 Expert. We all KNOW the engine compartment (the part where the power section goes ... you know, the engine block and cylinders) is the same size because the same engine block fits into it. What ISN'T the same size is the compartment aft of the engine compartment, where the auxiliary stage would go. I just got back from the museum and measured things on both the P-39 and the P-63. Go back to post #3,403 and look at the P-39 side views.

Notice the bulkhead just below the antenna mast and the bulkhead just aft of the rearmost exhaust stack. From the bulkhead under the antenna mast to the aft exhaust stack is 3" 9" on a P-39 (the one I used is a P-39N) and 4' 5" on the P-63. If you subtract the smaller measurement from the larger measurement, the difference is 8 inches using the "Measure" app on my cell phone. Doesn't sound like much, but it is the difference between the Aux stage fitting and not fitting. Also, the rear area in the P-63 is big enough for the Aux stage supercharger. In the P-39, it is NOT big enough for the aux-stage to fit inside. As I stated in an earlier post, you COULD knock some sheet metal out to shoehorn it in, but then you'd STILL have the CG issue that requires moving the wing or the pilot and you'd STILL have to supply a bearer mount for the aux stage after you move the existing bulkhead and whatnot back there, like oxygen bottles. Moving the pilot forward would put him firmly in the cannon breech area, so he'd not likely relish that idea. Seems better to move the wings aft a bit for CG purposes.

Hence, the P-63 Kingcobra, with all the changes built in to make a aux-stage Allison work.

You CANNOT fit a 2-stage Allison into a stock P-39 airframe and, if you DID by banging sheet metal around, the aux stage would have no support to mount on, and it would rock back on the tail.

Not sure what you are thinking, but I have had two different museums that own P-39s, one of which has restored both P-39s and P-63s to flight status, tell me a 2-stage Allison won't fit in a P-39. My own measurements confirm that. Now, I can't show you a 2-stage Allison installation in our P-63, because ours is being restored with a single-stage engine, but there are several such pictures floating about. Here is one:

https://ww2aircraft.net/forum/attachments/p-63-ephrata-airfield-july-44-jpg.356901/


You can see the compartment aft of the power section is pretty full.

If you want to insist that you can make an aux-stage Allison fit into a P-39, please feel free. Nobody ELSE can get it done. Perhaps you can get into Mr. Peabody's WayBack Machine and go back to show them all how it is done. Failing that, since Sherman and Mr. Peabody might not be very cooperative, SHOW ME HOW TO DO IT. Get Allison Aux-stage engineering drawings and a Bell P-39 engineering drawings and show that the equipment and the supports fit where everyone else says they won't fit. Show it clearly and with measurements, accounting for everything needed to make a 2-stage Allison run.

Or ... please stop making that claim.

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## fubar57 (Jul 29, 2021)

Greg…..just who do you think you are bringing measurements and fact to this thread

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## GregP (Jul 29, 2021)

Sorry, I forgot, I'm just a former (not current) pilot. So, my posts must be hearsay.

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## fubar57 (Jul 29, 2021)



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## FLYBOYJ (Jul 29, 2021)

GregP said:


> Hey P-39 Expert. We all KNOW the engine compartment (the part where the power section goes ... you know, the engine block and cylinders) is the same size because the same engine block fits into it. What ISN'T the same size is the compartment aft of the engine compartment, where the auxiliary stage would go. I just got back from the museum and measured things on both the P-39 and the P-63. Go back to post #3,403 and look at the P-39 side views.
> 
> Notice the bulkhead just below the antenna mast and the bulkhead just aft of the rearmost exhaust stack. From the bulkhead under the antenna mast to the aft exhaust stack is 3" 9" on a P-39 (the one I used is a P-39N) and 4' 5" on the P-63. If you subtract the smaller measurement from the larger measurement, the difference is 8 inches using the "Measure" app on my cell phone. Doesn't sound like much, but it is the difference between the Aux stage fitting and not fitting. Also, the rear area in the P-63 is big enough for the Aux stage supercharger. In the P-39, it is NOT big enough for the aux-stage to fit inside. As I stated in an earlier post, you COULD knock some sheet metal out to shoehorn it in, but then you'd STILL have the CG issue that requires moving the wing or the pilot and you'd STILL have to supply a bearer mount for the aux stage after you move the existing bulkhead and whatnot back there, like oxygen bottles. Moving the pilot forward would put him firmly in the cannon breech area, so he'd not likely relish that idea. Seems better to move the wings aft a bit for CG purposes.
> 
> ...


Great info Greg - and I like the way our friend talks about moving structure and components around as if he was kitbashing a 1/48th scale P-39 model (no disrespect to my modeling friends). No mention of having to place this "Frankenstein" into a jig so the rest of the structure doesn't warp or bend. Sure, at the factory "they" can do almost anything, *get that Wayback machine and send our friend to Bell around 1941, he could have been the VP of P-39 Engineering and Production!

EDIT - *I better watch that, he might start believing he was qualified to hold such a position!


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## Thumpalumpacus (Jul 29, 2021)

GregP said:


> Sorry, I forgot, I'm just a former (not current) pilot. So, my posts must be hearsay.



Well, did you read the manual? That should be sufficient qualification.

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## pbehn (Jul 29, 2021)

Being a simpleton I asked the obvious question a while ago, if you can easily fit a two stage supercharged Allisson engine into a P-39 why did the P-63 ever get made? I never got an answer, but I never do.

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## FLYBOYJ (Jul 29, 2021)

It's been a while since I knocked around this site, but some great Allison V1710 info.

_V-1710-E engines were designed for use with remote gearboxes. Three variants powered single-engine Bell P-39 (LF, RF, Firing), P-63 and XFL-1 fighters, all of which had the engine behind the pilot. This arrangement made room for a 37mm cannon firing through the propeller hub. A fourth variant powered the Douglas XB-42. P-39 engines used single-stage superchargers, while some P-63 engines added a variable-speed auxiliary altitude supercharger stage (LF, RA). The XB-42 employed two V-1710-E23 (L, RF) engines to drive contra-rotating pusher propellers. A turbocompound engine, the V-1710-E27 (L, A, R, T) was built and tested, as were numerous other variations on the shaft-driven remote gearbox (90°, Tandem, Tandem).

V-1710-E Images: F, LF, L, LA, A, RA, R, RF, T, B, with Driveshaft, Gearbox._



Allison Piston Engine Images



I believe this is what the 2 stage V-1710 engine looked like (V-1710-G)





Here's the stock P-39 engine






Here's the gearbox - "Just Because" 







S
 Shortround6
any comments?

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## Thumpalumpacus (Jul 29, 2021)

FLYBOYJ said:


> It's been a while since I knocked around this site, but some great Allison V1710 info.
> 
> V-1710-E engines were designed for use with remote gearboxes. Three variants powered single-engine Bell P-39 (LF, RF, Firing), P-63 and XFL-1 fighters, all of which had the engine behind the pilot. This arrangement made room for a 37mm cannon firing through the propeller hub. A fourth variant powered the Douglas XB-42. P-39 engines used single-stage superchargers, while some P-63 engines added a variable-speed auxiliary altitude supercharger stage (LF, RA). The XB-42 employed two V-1710-E23 (L, RF) engines to drive contra-rotating pusher propellers. A turbocompound engine, the V-1710-E27 (L, A, R, T) was built and tested, as were numerous other variations on the shaft-driven remote gearbox (90°, Tandem, Tandem).
> 
> ...



Where dos the cannon fit into this? Anyone have any pics? Wiki's kakking out on me.


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## FLYBOYJ (Jul 29, 2021)

Thumpalumpacus said:


> Where dos the cannon fit into this? Anyone have any pics? Wiki's kakking out on me.

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## Thumpalumpacus (Jul 29, 2021)

That's one mighty small ammo feed.

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## 33k in the air (Jul 29, 2021)

Thumpalumpacus said:


> He clearly only replies when he thinks it offers him an opportunity to advance his agenda.



To put this thread into paraphrased movie line terms:

P-39 Expert: "P-39, Cadillac of the skies!"
The Forum: "Why do you say this to us when you know we will debate you for it?"


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## SaparotRob (Jul 29, 2021)

More like (from the Princess Bride): "I don't think this means what you think it means."

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## Thumpalumpacus (Jul 29, 2021)

33k in the air said:


> To put this thread into paraphrased movie line terms:
> 
> P-39 Expert: "P-39, Cadillac of the skies!"
> The Forum: "Why do you say this to us when you know we will debate you for it?"



Trollery though it is, I appreciate that them who know more base their replies on good, sound footing, which allows those of us less-informed to learn better how to sniff out sloppy stuff.

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## tyrodtom (Jul 29, 2021)

P-39 Expert said:


> Nanette was fiction, Angels Twenty was fact based on the same location and time period. From the book: "We (two planes) started our takeoff run before the first element (two planes) was off the ground. They began their turn, a wide gentle swing. Wingman and I were able to turn easily inside them and so put the flight in proper formation. By the time we were on course for the coordinate Blue Flight was with us, all in position." That was only two flights (eight planes, half a squadron), but the process was very quick and simple.
> 
> Park was no friend of the P-39, but in the other book he made it clear that the biggest fault was too much weight, coming mainly from the wing guns and too much armor plate. In neither book did he say that the plane was difficult or dangerous to fly and was particularly easy to take off and land.
> 
> I thoroughly enjoyed both books, finding them at times laugh out loud funny at the situations he and his squadron mates found themselves in both in combat and on leave. I thought it was an accurate portrayal of day to day life on a forward base in NG during a time early on when the AAF was on the defensive. I recommend both books as very entertaining for someone interested in WW2 aviation.


Nice twist P-39 Expert, Nanette is fiction, Angels 20 is the truth, and nothing but the truth.
Strange that the forming up procedures revealed in Nanette fits within known accepted SOP, and your take from Angels 20 does not.

Nanette is about the middle period, and moves into the late period at Port Moresby, and it's nearby airfields , not the early period.
He mentions P-38s being present from the beginning of his account, and also N model P-39s.

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## SaparotRob (Jul 29, 2021)

GregP was elbows deep in an actual, honest to glory, no fooling' around P-39. His pals restore, repair, rebuild, fly actual P-39's. They actually take stuff out and put stuff back in to REAL P-39's. I'm sure some of these guys have some FAA mandated qualification. They say you can't PHYSICALLY do it. 

"You canna' change the laws of physics."
Lt Cmdr Montgomery Scott

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## Thumpalumpacus (Jul 29, 2021)

SaparotRob said:


> GregP was elbows deep in an actual, honest to glory, no fooling' around P-39. His pals restore, repair, rebuild, fly actual P-39's. They actually take stuff out and put stuff back in to REAL P-39's. I'm sure some of these guys have some FAA mandated qualification. They say you can't PHYSICALLY do it.
> 
> "You canna' change the laws of physics."
> Lt Cmdr Montgomery Scott



You done did it, introducing science-fiction into this already-absurd tale from beyond.

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## SaparotRob (Jul 29, 2021)

Thumpalumpacus said:


> You done did it, introducing science-fiction into this already-absurd tale from beyond.



and I didn't even read the manual.

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## Thumpalumpacus (Jul 29, 2021)

SaparotRob said:


> and I didn't even read the manual.



Yabut do you play a doctor on TV? Or perhaps stayed recently in a Holiday Inn Express?

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## nuuumannn (Jul 29, 2021)

Thumpalumpacus said:


>




"Dogs and cats living together..." LMAO!

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## Thumpalumpacus (Jul 29, 2021)

nuuumannn said:


> "Dogs and cats living together..." LMAO!



One way or another, Bill Murray belongs in a Groundhog thread.











It's almost as if his monomaniacal movie portrayals portended this thread.

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## GrauGeist (Jul 29, 2021)

And in the ads below...






Perfect!

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## Thumpalumpacus (Jul 29, 2021)




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## DerAdlerIstGelandet (Jul 29, 2021)

GrauGeist said:


> And in the ads below...
> 
> View attachment 634602
> 
> ...



This pretty much sums up this thread...

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## GrauGeist (Jul 29, 2021)

Great, so now that the "Never Ending Story" has entered the loop, we need to know the CoG of the Luck Dragon...

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## Stig1207 (Jul 29, 2021)

drgondog said:


> Stig, the Eagle Squadrons were so designated (4th FG).
> 
> The 31st FG had 307,308 and 309FS, all organized into 31st FG in May 1942. You can find the 39th, 40th and 41st in the 35th FG. My father commanded the 35th in Japan - we were at Johnson AFB. Jeff Ethell's father Irv was a 39th FS CO during our time there.



Yeah, I wrote that in a bit of a hurry, and got the squadrons of the 4th and 31st mixed up.


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## Stig1207 (Jul 29, 2021)

pbehn said:


> Rolf Gunther Hermichen was in the LW at the start of the war, served in the French campaign, The Battle of Britain, on the eastern front before returning to France in 1942. He claimed a Hurricane at the end of July which was a Hurricane, a Spitfire on the 18 August, another Spitfire on the 19 August plus another he claimed as an Airacobra. This was his 18th claim 5 previous claims for Spitfires. He must have had reasons to think it was a P-39.
> 
> 
> 
> Focke-Wulf 190s Over Dieppe



From the link:


> At around 11:30, FW 190s appeared in great numbers over the beachhead, resulting in the fiercest combat of the day. Rolf Hermichen of 3./J.G. 26 claimed destruction of a P-39 at 11:38 (a case of mis-identification).



Oops, I see you already addressed this in post #3414 (!!!). So many postings in this thread, I can't keep up.

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## Thumpalumpacus (Jul 30, 2021)

GrauGeist said:


> Great, so now that the "Never Ending Story" has entered the loop, we need to know the CoG of the Luck Dragon...



Obviously tail-heavy. It was, after all, dragon its tail.

I'll show myself the door.

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## buffnut453 (Jul 30, 2021)

Thumpalumpacus said:


> You done did it, introducing science-fiction into this already-absurd tale from beyond.




I knew there was a reason I liked you! Madness, one of my all-time favourite bands. Saw them live in Birmingham (NOT Alabama) in 2004. Fantastic concert - place was rocking! 😃

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## Thumpalumpacus (Jul 30, 2021)

buffnut453 said:


> I knew there was a reason I liked you! Madness, one of my all-time favourite bands. Saw them live in Birmingham (NOT Alabama) in 2004. Fantastic concert - place was rocking! 😃



When that song hit Stateside, in 82/83, I was a confirmed metalhead and had no use for anything that didn't _rock_ -- but even my 16-year-old ears heard that that rocked, like mad. No Judas Priest Harley-Davidson stuff, no Iron Maiden Eddie crap, just killin' the groove.

I bet that show had you worn out.

ETA: Sabbath fan here (reference my avatar), I know there's another Birmingham in the world


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## Peter Gunn (Jul 30, 2021)

Here's my take on what's going on in this thread, start at the 1:50 mark, from 1:50 to 2:56 is how I see this thread:

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## eagledad (Jul 30, 2021)

Gentlemen

The 2 stage Allison engine E9 (V-1710-47) was used on the XP-39E aircraft. However, to get it to fit, *the fuselage was lenghtened 1.75 feet to accomodate the longer Allison E9 engine.* As GregP and many others have written, one could not just replace the the single stage Allison engine with the 2 stage engine in a standard P-39 without modifications of the airframe. IMHO, the P-39 was looked upon unfavorably by the US and GB because it did not have the *range/combat radius* required by those 2 air forces nor did it have the required *high altitude performance* that was desired. (Again stated by many on this forum) Again my opinion, the P-39 did relatively well with the Soviet Air Force because air combat on that front was *mostly* low altitude (under 20,000 feet) and the airfields were relatively close to the front (combat radius not as critical).

Eagledad

Source: *Cobra*, by Birch Matthews pages 170 to 174. pages include a table by Bell engineers comparing the dimensions of the P-39D and XP-P39E.

I need to get an asprin for my headache.

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## ThomasP (Jul 30, 2021)

re weights, dimensions, and CoG of the different 'E' series engines.

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## drgondog (Jul 30, 2021)

eagledad said:


> Gentlemen
> 
> The 2 stage Allison engine E9 (V-1710-47) was used on the XP-39E aircraft. However, to get it to fit, *the fuselage was lenghtened 1.75 feet to accomodate the longer Allison E9 engine.* As GregP and many others have written, one could not just replace the the single stage Allison engine with the 2 stage engine in a standard P-39 without modifications of the airframe. IMHO, the P-39 was looked upon unfavorably by the US and GB because it did not have the *range/combat radius* required by those 2 air forces nor did it have the required *high altitude performance* that was desired. (Again stated by many on this forum) Again my opinion, the P-39 did relatively well with the Soviet Air Force because air combat on that front was *mostly* low altitude (under 20,000 feet) and the airfields were relatively close to the front (combat radius not as critical).
> 
> ...


This was huge but the bigger and more costly change was moving the wing to accommodate change in static margin due to CG shift.

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## pbehn (Jul 30, 2021)

Didnt anyone ever say "just put the engine in the front Larry"?

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## GrauGeist (Jul 30, 2021)

If the engine is up front, where do we put the nose armor?

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## pbehn (Jul 30, 2021)

GrauGeist said:


> If the engine is up front, where do we put the nose armor?


In front of the pilot where those cheating Brits put it first on the Spitfire.

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## FLYBOYJ (Jul 30, 2021)

GrauGeist said:


> If the engine is up front, where do we put the nose armor?


In the same place because there's some black fluid there! (Go to 0:51)


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## BiffF15 (Jul 30, 2021)

FLYBOYJ said:


> In the same place because there's some black fluid there! (Go to 0:51)



What was burning so heavily from the nose? Would there really have been that much oil in the nose case?

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## special ed (Jul 30, 2021)

Apparently the video creators forgot the P-39 did not have an engine up front.

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## Shortround6 (Jul 30, 2021)

pbehn said:


> Didnt anyone ever say "just put the engine in the front Larry"?


Yep................................










Engine was in-between the pilot and the cannon

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## fubar57 (Jul 30, 2021)

Very MiG-3 like. Off to see which was better, the MiG or the Groundhog.......................................


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## GregP (Jul 30, 2021)

Actually, I have to apologize for my post above. The airplane shown in the pic has a single-stage engine installed in it. An aux-stage engine is shown below:






Notice that engine stand has bearers for the aux stage attached even though there are no engine mounts attached to the engine block! The engine mount points are the two small rectangles with 4 holes each in them that rest on the stand. This is a later aux-stage engine, with a charge cooling box between the aux S/C and the integral S/C., but the aux stage gets supported by a mount.

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## BiffF15 (Jul 30, 2021)

Shortround6 said:


> Yep................................
> 
> 
> 
> ...


Trying to shoot over that nose would be a "beech". Long nose, pilot down in the fuselage, minor blister of a canopy allowing no lookdown over the snout.


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## GrauGeist (Jul 30, 2021)

pbehn said:


> In front of the pilot where those cheating Brits put it first on the Spitfire.


Well, those pesky Brits could do that because they didn't have a cumbersom gas heater in the way...

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## FLYBOYJ (Jul 30, 2021)

BiffF15 said:


> What was burning so heavily from the nose? Would there really have been that much oil in the nose case?


I don't think the producers understood how the P-39 was configured!

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## GrauGeist (Jul 30, 2021)

BiffF15 said:


> What was burning so heavily from the nose? Would there really have been that much oil in the nose case?


The gearbox oil tank was only two gallons - I know oil can burn fiercely when it's super-heated, but that video was way over the top.

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## FLYBOYJ (Jul 30, 2021)

GrauGeist said:


> The gearbox oil tank was only two gallons - I know oil can burn fiercely when it's super-heated, but that video was way over the top.


Good flying scenes if not entertaining - I'm looking to see when the whole movie is available.

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## Dash119 (Jul 30, 2021)

GregP said:


> Actually, I have to apologize for my post above. The airplane shown in the pic has a single-stage engine installed in it. An aux-stage engine is shown below:
> 
> View attachment 634749
> 
> ...


I believe this is the V-1710-F-32(-119) variant used in the Lightweight P-51J.


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## GregP (Jul 30, 2021)

Yah. It's the only pic of an aux-stage engine I could find with any indication of an aux-stage bearer mount.

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## special ed (Jul 30, 2021)

.Re: post 64 by eagledad in FW-190F: how effective... I wonder why the Russians didn't use their wonder weapon super groundhog to catch the Fw 190F when their Yak-3,Yak-9 couldn't and La-7 only barely could.


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## Dash119 (Jul 30, 2021)

GregP said:


> Yah. It's the only pic of an aux-stage engine I could find with any indication of an aux-stage bearer mount.


Greg,

Not being critical at all, I knew where you were going with the image. I just have to comment when my profile image is used in a post...

Kim

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## pbehn (Jul 30, 2021)

Shortround6 said:


> Yep................................
> 
> 
> 
> ...


Did anyone slap Larry upside the head and say "squeezing the pilot in behind the engine isnt putting the engine in the front"

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## P-39 Expert (Jul 30, 2021)

buffnut453 said:


> Please explain the term "construction drawings". I'm familiar with: Detail Drawings, which depict an individual part; Assembly Drawings, which describe an object made up of two or more parts; Installation Drawings, which shows a part or assembly in its installed location, and; Sectional View Drawings, which cut away part of an object to show the shape and construction along the cutting plane. There are also schematics which describe, at some degree of abstraction, systems within an aircraft. So what are "construction drawings"?
> 
> I presume you're referring to the "drawings" you cited in this post: XP-39 II - The Groundhog Day Thread. Those are Installation Drawings showing the station positions in the airframe. They ONLY show the distance between stations. They DO NOT show the height or width dimensions.
> 
> Just because compartments are "exactly the same length" does not mean that a 3-dimensional object will fit in that space. You need distances across length, width and height...and you also need to reflect any changes to those measurements to see if the physical space is sufficient...and, even then, there may be issues fitting an assembly into the available space because other parts or assemblies might get in the way.


Same width too.


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## P-39 Expert (Jul 30, 2021)

GregP said:


> Hey P-39 Expert. We all KNOW the engine compartment (the part where the power section goes ... you know, the engine block and cylinders) is the same size because the same engine block fits into it. What ISN'T the same size is the compartment aft of the engine compartment, where the auxiliary stage would go. I just got back from the museum and measured things on both the P-39 and the P-63. Go back to post #3,403 and look at the P-39 side views.
> 
> Notice the bulkhead just below the antenna mast and the bulkhead just aft of the rearmost exhaust stack. From the bulkhead under the antenna mast to the aft exhaust stack is 3" 9" on a P-39 (the one I used is a P-39N) and 4' 5" on the P-63. If you subtract the smaller measurement from the larger measurement, the difference is 8 inches using the "Measure" app on my cell phone. Doesn't sound like much, but it is the difference between the Aux stage fitting and not fitting. Also, the rear area in the P-63 is big enough for the Aux stage supercharger. In the P-39, it is NOT big enough for the aux-stage to fit inside. As I stated in an earlier post, you COULD knock some sheet metal out to shoehorn it in, but then you'd STILL have the CG issue that requires moving the wing or the pilot and you'd STILL have to supply a bearer mount for the aux stage after you move the existing bulkhead and whatnot back there, like oxygen bottles. Moving the pilot forward would put him firmly in the cannon breech area, so he'd not likely relish that idea. Seems better to move the wings aft a bit for CG purposes.
> 
> ...


Same size Greg. Same length, same width.


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## FLYBOYJ (Jul 30, 2021)

P-39 Expert said:


> Same size Greg. Same length, same width.





P-39 Expert said:


> Same width too.

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## buffnut453 (Jul 30, 2021)

P-39 Expert said:


> Same width too.



Then why do you have so many people, including staff who actually restore P-39s, saying that there isn't room for the supercharger? Are they all idiots who can't even use a tape measure?

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## P-39 Expert (Jul 30, 2021)

eagledad said:


> Gentlemen
> 
> The 2 stage Allison engine E9 (V-1710-47) was used on the XP-39E aircraft. However, to get it to fit, *the fuselage was lenghtened 1.75 feet to accomodate the longer Allison E9 engine.*


This is an error perpetuated over 75 years. The aft fuselage was lengthened, but lengthened aft of the engine compartment. Engine compartment is the same size on the P-39, P-39E, and P-63.


eagledad said:


> As GregP and many others have written, one could not just replace the the single stage Allison engine with the 2 stage engine in a standard P-39 without modifications of the airframe. IMHO, the P-39 was looked upon unfavorably by the US and GB because it did not have the *range/combat radius* required by those 2 air forces nor did it have the required *high altitude performance* that was desired.


P-39 with 120gal had 20% more fuel than a Spitfire V.


eagledad said:


> (Again stated by many on this forum) Again my opinion, the P-39 did relatively well with the Soviet Air Force because air combat on that front was *mostly* low altitude (under 20,000 feet) and the airfields were relatively close to the front (combat radius not as critical).
> 
> Eagledad
> 
> ...


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## pbehn (Jul 30, 2021)

P-39 Expert said:


> Same size Greg. Same length, same width.


So why waste time and money on the P-63?

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## P-39 Expert (Jul 30, 2021)

pbehn said:


> So why waste time and money on the P-63?


For the umpteenth time, the engine (V1710-93) was in production from April 1943 but the first P-63 airframe wasn't completed until October. Six months in mid 1943 was wasted when the engine could have been installed in a P-39.


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## buffnut453 (Jul 30, 2021)

P-39 Expert said:


> The aft fuselage was lengthened, but lengthened aft of the engine compartment. Engine compartment is the same size on the P-39, P-39E, and P-63.



Yes, because if you read Greg's post instead of just ignoring it, he says the supercharger fits into the compartment AFT of the engine compartment. Why do you persist in saying black is white when all evidence screams that you're wrong?

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## FLYBOYJ (Jul 30, 2021)

P-39 Expert said:


> This is an error perpetuated over 75 years. The aft fuselage was lengthened, but lengthened aft of the engine compartment. Engine compartment is the same size on the P-39, P-39E, and P-63.
> 
> P-39 with 120gal had 20% more fuel than a Spitfire V.


You realize that your credibility here is almost non existent. Until you start putting hands on hardware, I suggest you sit back in your armchair and just listen.

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## pbehn (Jul 30, 2021)

P-39 Expert said:


> P-39 with 120gal had 20% more fuel than a Spitfire V.


It had the same amount of fuel on board as a Spitfire VII, VIII or some Mk IX all you need to do is plumb in the wing leading edge tanks 25 gals for the pair, we have been through this many times. If internal fuel was the winner everyone would be in Fairey Battles.

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## FLYBOYJ (Jul 30, 2021)

P-39 Expert said:


> For the umpteenth time, the engine (V1710-93) was in production from April 1943 but the first P-63 airframe wasn't completed until October. Six months in mid 1943 was wasted when the engine could have been installed in a P-39.


And if this was such a great idea those really smart AAF officers (maybe the same ones you spoke about who designed those wonderful charts that you don't understand) "would have" saw fit to issue a contract to Bell to do this - or better yet, maybe Larry Bell "would have" went forward with company funds to show the AAF this great idea you came up with 77 years+ later.


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## pbehn (Jul 30, 2021)

P-39 Expert said:


> For the umpteenth time, the engine (V1710-93) was in production from April 1943 but the first P-63 airframe wasn't completed until October. Six months in mid 1943 was wasted when the engine could have been installed in a P-39.


Seriously, are you suggesting that the solution was there for six months and it only needed someone as bright as you to suggest it?

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## buffnut453 (Jul 30, 2021)

pbehn said:


> Seriously, are you suggesting that the solution was there for six months and it only needed someone as bright as you to suggest it?



It's a pretty impressive ego, to be sure!

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## buffnut453 (Jul 30, 2021)

FLYBOYJ said:


> You realize that your credibility here is almost non existent. Until you start putting hands on hardware, I suggest you sit back in your armchair and just listen.



I'd settle for him actually reading and comprehending posts from other people...or at least asking questions about things that are unclear to him.

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## Shortround6 (Jul 30, 2021)

A few dates that may be of interest.
*June 27, 1941* they (USAAC) placed an order for two prototypes of an enlarged version (of the P-39E) powered by the same Allison V-1710-47 engine. The designation was XP-63 (company designation was Model 24).

In *September of 1942*, even before the first flight of the prototype, the aircraft was ordered into production by the USAAF as the P-63A (Model 33)

The XP-63 Ser No. 41-19511 flew for the first time on *December 7, 1942*

The second prototype (41-19512) flew for the first time on *February 5, 1943*

The XP-63A flew for the first time on* April 26, 1943*

So the "expert" would have us believe that in all that time that they were working on the XP-39E and the P-63 projects (nearly two years just for the P-63 project) *NOBODY *walked over to a regular P-39 with a tape measure, spent a few minutes and called out across the hanger "hey guys, the new engine will fit in the old airplane!"

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## pbehn (Jul 30, 2021)

buffnut453 said:


> I'd settle for him actually reading and comprehending posts from other people...or at least asking questions about things that are unclear to him.


Years ago all I knew about the P-39 and P-63 was that, because the engine was installed in the middle of the fuselage of the P-39, putting a bigger engine in it needed a bigger plane which was the P-63. I have learned all sorts of interesting stuff from many posters and all of it supports what I knew before, probably because it is so bleedin' obviously obvious.

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## GrauGeist (Jul 30, 2021)

Greg LITERALLY climbed in there and measured it.
This means PHYSICALLY measured the ACTUAL genuine aircraft.

He didn't hold up "drawings" and compare the two and guess.

He was actually INSIDE the engine compartment to make the comparison.

How in the hell can anyone be so jaded as to dispute physical contact versus "drawings"?

When Greg posted the measurements and description of the engine bay interior from an ACTUAL aircraft he was literally inside of - you should have appreciated his effort and thanked him for going to the trouble and then perhaps felt a little stupid for arguing over a wrong point, while learning from the information.

But no, we can't have that now, can we?
Nope, we're going to beat the dead horse's carcass until it's dust and then stomp the dirt where the carcass was just for good measure...

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## FLYBOYJ (Jul 30, 2021)

Shortround6 said:


> So the "expert" would have us believe that in all that time that they were working on the XP-39E and the P-63 projects (nearly two years just for the P-63 project) *NOBODY *walked over to a regular P-39 with a tape measure, spent a few minutes and called out across the hanger "hey guys, the new engine will fit in the old airplane!"


*As they were being produced side-by-side!*

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## pbehn (Jul 30, 2021)

FLYBOYJ said:


> As they were being produced side-by-side!
> View attachment 634787


If only someone had walked across those lines and had a bit of a chat the whole world would have been different, maybe could have had colour TV too?

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## fubar57 (Jul 30, 2021)

GrauGeist said:


> Greg LITERALLY climbed in there and measured it.
> This means PHYSICALLY measured the ACTUAL genuine aircraft.
> 
> He didn't hold up "drawings" and compare the two and guess.
> ...

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## 33k in the air (Jul 30, 2021)

GrauGeist said:


> Nope, we're going to beat the dead horse's carcass until it's dust and then stomp the dirt where the carcass was just for good measure...



Yeah, well, maybe that horse had it coming.

It was always a mean, cantankerous beast!

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## Glider (Jul 30, 2021)

Thumpalumpacus said:


> @P-39 Expert[/USER]'s problem seems to be that he's making so many questionable claims and facing pushback from so many different angles that he's tying himself into knots trying to 1) answer an objection and 2) do so in such a manner that he doesn't undercut another answer of his to another objection.


My father was a man of many phrases and the one that sticks with this part of your posting is

'Oh what a tangled web we weave, when we practice too deceive'.

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## GregP (Jul 30, 2021)

P-39 Expert said:


> Same size Greg. Same length, same width.


OK, I give.

Exactly WHAT is the same size and width that I didn't already fully describe?

I already said that the engine compartment where the block goes is the same size. It's the compartment behind the engine bay, where the aux stage will go that is NOT the same size.

No wonder you can't read a chart since you can't read a clearly-worded reply and answer back without ambiguity.

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## FLYBOYJ (Jul 30, 2021)

GregP said:


> No wonder you can't read a chart since you can't read a clearly-worded reply and answer back without ambiguity.


Classic!


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## GregP (Jul 30, 2021)

Well, anyone who wants to come visit Chino, let me know via PM.

You can come to two different museums with me and measure until your heart is content. I'll even arrange for you to sit in the P-63 cockpit. We can also go to an Allison engine overaul shop and look at (and weigh, if we want to) an aux-stage supercharger and a remote nose case. We'll burn a steak and have a few beers.

Well, almost anyone ... I reserve the right to refuse hospitality, depending on the degree of Groundhoggery exhibited. I think a large majority would qualify for some friendly banter as we go check out this engine swap proposition and arrive at a joint conclusion to be posted in here.

We already KNOW how long a V-1710-93 Allison is - slightly over 215.5 inches. We already know how long a V-1710-35 Allison is - 194 inches. The length includes the nosecase. The difference in length is 21.5 inches unless my subtraction is incorrect. That length, sticks back into the rear compartment. But, hey, we can go verify that anytime and watch a few warbirds fly in the process.

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## pbehn (Jul 30, 2021)

GregP said:


> OK, I give.
> 
> Exactly WHAT is the same size and width that I didn't already fully describe?
> 
> ...


Facts have never had any influence on this discussion, that's proper groundhoggery.


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## PAT303 (Jul 30, 2021)

The definition of stupid is a person who has the inability to learn in the face of overwhelming facts.


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## DerAdlerIstGelandet (Jul 30, 2021)

While I think we all share the same sentiments, we all need to refrain from personal attacks and insults.

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## BiffF15 (Jul 30, 2021)

GregP said:


> Well, anyone who wants to come visit Chino, let me know via PM.
> 
> You can come to two different museums with me and measure until your heart is content. I'll even arrange for you to sit in the P-63 cockpit. We can also go to an Allison engine overaul shop and look at (and weigh, if we want to) an aux-stage supercharger and a remote nose case. We'll burn a steak and have a few beers.
> 
> ...


I'll pick up the steaks!

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## DerAdlerIstGelandet (Jul 30, 2021)

BiffF15 said:


> I'll pick up the steaks!



And I’m now officially joining...

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## FLYBOYJ (Jul 30, 2021)

GregP said:


> Well, anyone who wants to come visit Chino, let me know via PM.
> 
> You can come to two different museums with me and measure until your heart is content. I'll even arrange for you to sit in the P-63 cockpit. We can also go to an Allison engine overaul shop and look at (and weigh, if we want to) an aux-stage supercharger and a remote nose case. We'll burn a steak and have a few beers.
> 
> ...


I hoping to take you up on that! As we put the Covid crap behind us and as my girls are getting older, I'm hoping to hit my old haunts as a tourist/ spectator rather than an active participant. Chino is one of my targets!

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## Peter Gunn (Jul 30, 2021)

P-39 Expert said:


> For the umpteenth time, the engine (V1710-93) was in production from April 1943 but the first P-63 airframe wasn't completed until October. Six months in mid 1943 was wasted when the engine could have been installed in a P-39.


And for the umpteenth time...

No, you're wrong.

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## GregP (Jul 30, 2021)

BiffF15 said:


> I'll pick up the steaks!


Any time, Bifff15 and DerAdler, anytime. It would be fun anyway. Lots of great aircraft to see, good food, good company, a few beers.

There's no downside unless the V-1710-95 actually fits, that is. Then, we be fools.






Sometimes I crack myself up.

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## XBe02Drvr (Jul 31, 2021)

GregP said:


> Well, almost anyone ... I reserve the right to refuse hospitality, depending on the degree of Groundhoggery exhibited.


Damn! I had my bags mostly packed before I read this line. Ah heck, y'all have fun out there! Gotta go feed the hogs.

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## wuzak (Jul 31, 2021)

462 posts more to get to Page #200

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## ThomasP (Jul 31, 2021)

Does this support anyone's view?
These photos are of the same P-63 airframe under assembly, taken at the Bell factory in Wheatfield NY.

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## GregP (Jul 31, 2021)

Way cool, ThomasP! Best P-63 pic I've seen for looking at engine location is the overhead view. 

You can see the intake tube going into the internal supercharger housing perfectly. One of the main reasons we all know there is a bearer for the aux stage is that the intake to the internal S/C has rubber connections to the tube coming from the aux stage. That keeps it airtight, but won't support much weight. let along a couple of hundred pounds. The only other connection of any consequence is a very light driveshaft.

You can also see it is pretty wide right back to the bulkhead aft of the aux stage.

Nice pics.

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## Glider (Jul 31, 2021)

Its a great picture, beautifully labelled, very clear and obviously used a real aircraft as the subject. 

But and its a big but. Are all these facts as accurate as P39's sketch?

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## GrauGeist (Jul 31, 2021)

Glider said:


> But and its a big but. Are all these facts as accurate as P39's sketch?


Pretty sure this is the caliber of the "drawings" that the Authority keeps referring to...

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## GregP (Aug 1, 2021)

What airplane is that sketch?

Is that a Soviet BearScat? Or HellHat? Or CoarseHair?


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## XBe02Drvr (Aug 1, 2021)

GregP said:


> What airplane is that sketch?
> 
> Is that a Soviet BearScat? Or HellHat? Or CoarseHair?


No, it's a Soviet McGur 15, can't you tell? The prototype with the dummy prop on it to fool the spies.

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## DerAdlerIstGelandet (Aug 1, 2021)

GregP said:


> Is that a Soviet BearScat? Or HellHat? Or CoarseHair?


Why thats a P-39 that was not destroyed by the British and their crazy design requirements.

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## pbehn (Aug 1, 2021)

DerAdlerIstGelandet said:


> Why thats a P-39 that was not destroyed by the British and their crazy design requirements.


I think the P-39 was the first fighter to insist on its right to bare arms (see what I did there)?

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## fubar57 (Aug 1, 2021)

just me and the crickets tonight

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## GrauGeist (Aug 1, 2021)

fubar57 said:


> just me and the crickets tonight
> 
> View attachment 635348​


And the occasional tumbleweed...

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## FLYBOYJ (Aug 1, 2021)



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## ThomasP (Aug 1, 2021)

Me time!

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## 33k in the air (Aug 2, 2021)

I'd like to do another (somewhat) witty pun for this thread, but I think I've used them all up.

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## GrauGeist (Aug 2, 2021)

Seems like this thread came to a sudden halt.
Much like Bill Overstreet's P-39

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## GregP (Aug 2, 2021)

That groundhog has a donut and coffee.

Must be a cop, huh?

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## XBe02Drvr (Aug 2, 2021)

GregP said:


> That groundhog has a donut and coffee.
> 
> Must be a cop, huh?


And helmet-mounted SCATR tubes to boot. This militarization of law enforcement is getting out of hand!

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## XBe02Drvr (Aug 2, 2021)

fubar57 said:


> just me and the crickets tonight
> 
> Hey Buddy, so you escaped that plane crash after all and have been living in secrecy all these years? And the guys in the band have been jamming with you but have never blown your cover? We're supposed to believe that? THAT'LL BE THE DAY!

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## glennasher (Aug 2, 2021)

There is a nasty cloud of flies circling this thread. They think it is dead and rotting. I concur.

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## special ed (Aug 2, 2021)

All of you have caused me to get out P-39 books. Unfortunately, there is still varying opinion. First, remember during the depression any attack would be bombers coming in toward coastal areas. The defense would be interceptors. The P-38 and P-39 were interceptors and the XFM & YFM were bomber destroyers. The idea of escorts with the attacking bombers was thought not possible, which is why the USAAF was slow to catch on and unprepared in Europe. Dorr & Scutts (Crowood) point out positive reports from the Brits about it's speed and manoeuverablity. They dispell the myth that the Soviets used the 37mm as a tank buster because of it's low power and lack of armor penetration. By the time of Pearl Harbor the Brits opinion changed to "unsuitable". No mention of cockpit heater. The 37mm was a favorite of to the US army and as Mr. Bell had seen a demonstration of the cannon, he saw it as a plus to include in a prospective fighter. Birch Matthews work, "Cobra", has considerable info. I usually don't read the preface when I first get a book, so now reading the preface, Matthews points out myths such as the P-39E had laminar flow airfoil when it did not. He points out that the P-39 mission was always as an interceptor, not ground support or coastal defense. After the NACA report, Bell had to remove the turbosupercharger to have any hope of an army contract, needed to prevent company bankruptcy. Another critical problem at Bell Aircraft was the lack of "an exceptionally talented engineer equivalent to NAA, Lockheed, and Douglas." Bob woods refused to reconfigure the XFL-1 c.g. while still on paper. The problem remained, causing USN an easy out. Matthews points out the later P-63 never gained USAAF acceptance in a combat capacity because it had the shortest combat radius of any USN or USAAF fighter of the war. His research not mine, but checking easily available stats, is verified. Matthews conclusion it was due to clinging to the 37mm canon. Other books perpetuate the 390 mph ideas, such as Kinzey's "P-39 Airacobra" and Rick Mitchell's "Airacobra Advantage". Mitchell has a quote from Tex Johnston, test pilot later in the program, "The P-39 was truly a fine airplane when utilized for the mission for which it was designed. Many articles written by misinformed authors and /or unqualified pilots have adversely affected the reputation of a fine airplane." Kind of a quote from a company man, with ambiguity. Squadron's P-39 in action No.43 is more for modelers as is Kinzey's and Mitchell's books. I have yet to look in the Putnam book as I an tiring of the P-39 info. As far as a recommendation, Matthew's book is the one to study as he was a Bell employee with access to records, and as impartial as I have seen. Well written and documented.

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## GregP (Aug 2, 2021)

Nobody in here has really said or thought the P-39 was absolutely terrible. What we have said is basically:

1) The range was wholly inadequate, and it was. There was no way to really "fix it," either.
2) The single-stage engine meant it was pretty good below about 15,000 feet and not much good above that altitude. By 20,000 feet, the airplane was flying, but wasn't exactly a "fighter." Unlike most other fighters, it never got a big change in horsepower. The Spitfire went from 1,000 hp to over 2,000. The P-39 went from 1,000 hp to 1,325. There is no reason to expect great jumps in performance from such a modest power increase, and they certainly didn't get it.
3) The potential for growth was woefully lacking.
4) They never did analyze the airplane when the ammunition had been used up. Had they done so, they would have seen what the airplane was being accused of by service pilots; tumbling (actually a Lomcevak maneuver).
5) It actually did the job it was specified for decently well. It wasn't very adaptable to other missions because it couldn't go very far or very high, and couldn't carry much of an ordnance load. Nobody seemingly had much use for the mission for which the P-39 was designed (low-altitude, short-range interceptor), so nobody really wanted it except the Soviet Union. If they got it anyway, it wasn't very adaptable to other missions except local short-range CAP. The British had use for a low-altitude interceptor in the V-1 crisis, but the P-39 wasn't fast enough had it been available and it was basically out of British service by that time anyway.

So, the P-39 was basically unwanted and not of overly much use if you happened to have it. It made a great squadron hack and COULD be used to cool off the squadron beer kegs in a pinch. It was definitely more fun to fly than an AT-6. It was likely our best product supplied to the Soviet Union, who wanted a short-range, low-altitude interceptor to support their ground war with the Germans. The P-39 was great packaging for what the Soviets really wanted: a radio.

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## P-39 Expert (Aug 2, 2021)

ThomasP said:


> Does this support anyone's view?
> These photos are of the same P-63 airframe under assembly, taken at the Bell factory in Wheatfield NY.
> View attachment 634887
> 
> ...


As you can see attached for the umpteenth time the length of the engine compartment is the exact same for the P-39 as it is for the P-63, 90.25 inches. Width of both is also the exact same. If the aux stage fit in the P-63 it would fit in the P-39. It was installed in a P-39D fuselage as the P-39E.

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## fubar57 (Aug 2, 2021)

LMFAO!!!!!!! To hell with actual measuring

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## drgondog (Aug 2, 2021)

P-39 Expert said:


> As you can see attached for the umpteenth time the length of the engine compartment is the exact same for the P-39 as it is for the P-63, 90.25 inches. Width of both is also the exact same. If the aux stage fit in the P-63 it would fit in the P-39. It was installed in a P-39D fuselage as the P-39E.


For the umpteenth time, independent of any miracle to squeeze the 10# engine into a 9# Compartment, major re-design would be required to make it flyable. Look into the major differences between the P-63 and P-39. As far as persuasive ability, you much remind me of a hound barking at the moon.

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## buffnut453 (Aug 2, 2021)

P-39 Expert said:


> As you can see attached for the umpteenth time the length of the engine compartment is the exact same for the P-39 as it is for the P-63, 90.25 inches. Width of both is also the exact same. If the aux stage fit in the P-63 it would fit in the P-39. It was installed in a P-39D fuselage as the P-39E.



I'll repeat slowly because you're clearly not reading/understanding what other people have written....

AUXILIARY.....STAGE....DIDN'T.....FIT....IN....THE...ENGINE....COMPARTMENT. 

AUX....STAGE...WENT....IN....THE....COMPARTMENT....AFT....OF....THE....ENGINE....COMPARTMENT. 

THAT...AFT....COMPARTMENT....WAS....DIFFERENT....IN....THE....XP-39E....AND....P-63....COMPARED....TO.....P-39D.

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## Glider (Aug 2, 2021)

P-39 Expert said:


> As you can see attached for the umpteenth time the length of the engine compartment is the exact same for the P-39 as it is for the P-63, 90.25 inches. Width of both is also the exact same. If the aux stage fit in the P-63 it would fit in the P-39. It was installed in a P-39D fuselage as the P-39E.


OK I Confess, your right. Your sketch to a manual is so much more accurate than the photos of the real aircraft, taken by the manufacturers, and measurements taken by people with access to the real aircraft. So much more accurate than the designers who put the aircraft together and the engineers that serviced the aircraft. 
Your engineering insight is so much more than people in this forum who have decades of experience in all aspects of aviation engineering. I should know that you are so trustworthy we should believe what you say and the proven accusations that you cherry pick aspects of documents are just a figment of our imagination.

I really don't know why I didn't agree with you from the start. How could I be so stupid.

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## GregP (Aug 2, 2021)

I didn't really want to say this, but you are emotionally draining, P-39 Expert. We have had some previously-banned members in here who had theories about "thrust columns" and other aerial oddities, but nobody until you completely ignored reason.

All of us already agreed with you that the engine compartment was the same size. You can't seem to wrap your head around that fact that the 2-stage Allison occupied more than one compartment in the airframe, and the second compartment is where the P-39 isn't quite big enough. Your obsession with the P-39 is meaningless since the P-39 is all but forgotten by the general public. This thread notwithstanding, the P-39 is less than a footnote in WWII history, and the aggravation of trying to speak with you when you won't read and respond to our posts point by point is more than the potential benefits of continuing the discussion, at least to me.

Best of luck to you sir. 

May the wind at your back always be your own. 

Cheers.

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## fubar57 (Aug 2, 2021)



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## pbehn (Aug 2, 2021)

From wiki (again)

XP-39EBell Model 23. three P-39Ds modified for ground and flight testing first flown 21 February 1942.[75]​ Intended for 2,100 hp (1,600 kW) Continental I-1430-1 engine but only flown with 1,325 hp (988 kW) Allison V-1710-47 engine. Used to test various wing and vertical tails. Fuselage lengthened by 21 in (530 mm) and used in the development of the P-63. The production variant, with the Continental engines was to be designated P-76; there was no Bell XP-76 as such.[75]​

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## buffnut453 (Aug 2, 2021)

pbehn said:


> From wiki (again)
> 
> XP-39EBell Model 23. three P-39Ds modified for ground and flight testing first flown 21 February 1942.[75]​ Intended for 2,100 hp (1,600 kW) Continental I-1430-1 engine but only flown with 1,325 hp (988 kW) Allison V-1710-47 engine. Used to test various wing and vertical tails. Fuselage lengthened by 21 in (530 mm) and used in the development of the P-63. The production variant, with the Continental engines was to be designated P-76; there was no Bell XP-76 as such.[75]​



AND....THE....21".....EXTENSION....ENABLED....THE....LARGER....AFT.....COMPARTMENT....FOR....THE....AUX....STAGE.

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## pbehn (Aug 2, 2021)

buffnut453 said:


> I'll repeat slowly because you're clearly not reading/understanding what other people have written....
> 
> AUXILIARY.....STAGE....DIDN'T.....FIT....IN....THE...ENGINE....COMPARTMENT. AUX....STAGE...WENT....IN....THE....COMPARTMENT....AFT....OF....THE....ENGINE....COMPARTMENT. THAT...AFT....COMPARTMENT....WAS....DIFFERENT....IN....THE....XP-39E....AND....P-63....COMPARED....TO.....P-39D.


If we ever discuss anything new it ceases to be a groundhog thread, as I see it you can fit it all in a P-39 and then all you need to do is move the wing and extend the tail.

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## SaparotRob (Aug 2, 2021)

Somehow, I think someone here should be fronting for the Flat Earth Society.

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## FLYBOYJ (Aug 2, 2021)

P-39 Expert said:


> As you can see attached for the umpteenth time the length of the engine compartment is the exact same for the P-39 as it is for the P-63, 90.25 inches. Width of both is also the exact same. If the aux stage fit in the P-63 it would fit in the P-39. It was installed in a P-39D fuselage as the *P-39E.*


You mean "XP-39." Your point was a "could have, would have, should have scenario, after the first XP-39E was destroyed during *spin testing. *Imagine that!

The P-39D I believe had a V-1710-35 engine. Not only did the XP-39E have a V-1710-47, but it was lengthened by 21 inches. Imagine that!

From Joe Baugher's site.

_"The XP-39E had a much better high-altitude performance than other Airacobra variants. It was redesignated XP-76 and no less than 4000 were ordered by the USAAF. However, *the new design was considered to be inferior to the basic Airacobra in many respects, and the order for the XP-76 was later cancelled in its entirety. *Nevertheless, the XP-39E was to provide some valuable basic data for the later P-63 Kingcobra."_

So "IF" there was an inkling of thought to put the 2 stage supercharger in any production P-39 model (providing it fit and I don't think it "would have"), that would have been the time to do it! (Mid 1942)

Why wasn't it done? Because Bell (with a contract award from the AAF) went forward with the P-63 which in the end was too little too late. *AND THE ENGINE DIDN'T FIT!!!!*

Could have, would have, should have.

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## DerAdlerIstGelandet (Aug 2, 2021)

What we’ve got here is failure to communicate. Some men, you just can’t reach. So, you get what we had here last week. Which is the way he wants it. Well, he gets it.

And I don’t like it anymore than you men...

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## Milosh (Aug 2, 2021)



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## GregP (Aug 2, 2021)

Is that one of those "Q" props?

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## fubar57 (Aug 2, 2021)

GregP said:


> Is that one of those "Q" props?


Those are Bell Speed Propellers. They were bent that way to improve speed and climb to 20,000 ft..

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## buffnut453 (Aug 2, 2021)

fubar57 said:


> Those are Bell Speed Propellers. They were bent that way to improve speed and climb to 20,000 ft..



No, silly, they bent it backwards to reduce frontal drag. The manual didn't say that WASN'T correct....so, ergo, it MUST BE correct, right?

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## pbehn (Aug 2, 2021)

FLYBOYJ said:


> You mean "XP-39." Your point was a "could have, would have, should have scenario, after the first XP-39E was destroyed during *spin testing. *Imagine that!
> 
> The P-39D I believe had a V-1710-35 engine. Not only did the XP-39E have a V-1710-47, but it was lengthened by 21 inches. Imagine that!
> 
> ...


If you put this with the Wiki articles on the P-39E and the development of the P-63 then the "P-39E" as a type were development airframes a bit like the Rolls Royce Mustang X (someone has to pay). As far as I can see it only flew with the -47 engine, but the initial contract was also for tests with Continental and Packard engines. Later stuff about installing the auxilliary supercharger and lengthening the airframe is a separate issue, using someone elses airframes for mock ups and trial fits when developing the P-63.

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## Dash119 (Aug 2, 2021)

buffnut453 said:


> No, silly, they bent it backwards to reduce frontal drag. The manual didn't say that WASN'T correct....so, ergo, it MUST BE correct, right?


No, no, no... Bending the props in this manner moves the CoG aft allowing the removal of the IFF.

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## pbehn (Aug 2, 2021)

Dont the blades fold back when the elastic band has run out of power?

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## GrauGeist (Aug 2, 2021)

Dang...and here I thought the blades were bent back due to it's wicked jet-killer speed...

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## XBe02Drvr (Aug 2, 2021)

pbehn said:


> Dont the blades fold back when the elastic band has run out of power?


Only in Wakefield County, elsewhere they stay extended.

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## special ed (Aug 2, 2021)

Birch Matthews in his book, Cobra, covers the XP-39E. Three were contracted, two for flight and one structure test. The first, 41-19501 and the second 41-19502. To build the XP-39E, major portions of the wing and fuselage changed. Wingspan and root chord increased. A new center section allowed the new thicker airfoil to include two .50s in each wing, giving six .50s and the ever present 37mm. The fuselage was LENGTHENED 1.75 feet to accommodate THE LONGER Allison V-1710-E9 (-47) BECAUSE OF THE OVERALL LENGTH WITH THE AUX STAGE SUPERCHARGER. The normal gross weight came in just under 9000 pounds making it the heaviest Airacobra ever built. The first acft was used for handling qualifications with the temporary engine and crashed during spin tests after 15 hours. The second acft had the -47 engine and was used only for performance tests. A replacement third aircraft was ordered and built, 42-71464, with no armor, armament and basic radio. Although the second acft reached 393 mph, the USAAF saw no further need for the E model. All this reading is going to make me the new P-39 expert although my favorite is the P-38. I had forgotten how much data on the P-39 and variations, as well as the P-63, Matthews has collected. He actually begins the Bell story in 1934, the very beginning of the company . Our resident P-39 Expert should make this his textbook and study for a degree.

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## fubar57 (Aug 2, 2021)

Those are just silly words, not to be taken seriously as Birch Matthews isn't a P-39 Expert

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## GrauGeist (Aug 2, 2021)

How can Birch Matthews be taken seriously if he doesn't have the word "expert" in his name?

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## buffnut453 (Aug 2, 2021)

GrauGeist said:


> How can Birch Matthews be taken seriously if he doesn't have the word "expert" in his name?



But you can make Etsbirt from some of the letters....which sounds kindda close.

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## SaparotRob (Aug 2, 2021)

special ed said:


> Birch Matthews in his book, Cobra, covers the XP-39E. Three were contracted, two for flight and one structure test. The first, 41-19501 and the second 41-19501. To build the XP-39E, major portions of the wing and fuselage changed. Wingspan and root chord increased. A new center section allowed the new thicker airfoil to include two .50s in each wing, giving six .50s and the ever present 37mm. The fuselage was LENGTHENED 1.75 feet to accommodate THE LONGER Allison V-1710-E9 (-47) BECAUSE OF THE OVERALL LENGTH WITH THE AUX STAGE SUPERCHARGER. The normal gross weight came in just under 9000 pounds making it the heaviest Airacobra ever built. The first acft was used for handling qualifications with the temporary engine and crashed during spin tests after 15 hours. The second acft had the -47 engine and was used only for performance tests. A replacement third aircraft was ordered and built, 42-71464, with no armor, armament and basic radio. Although the second acft reached 393 mph, the USAAF saw no further need for the E model. All this reading is going to make me the new P-39 expert although my favorite is the P-38. I had forgotten how much data on the P-39 and variations, as well as the P-63, Matthews has collected. He actually begins the Bell story in 1934, the very beginning of the company . Our resident P-39 Expert should make this his textbook and study for a degree.


So Bell Aircraft, with their plans and their actual planes that they built, lengthened the fuselage, in their factory, to get that power plant in. The wings were different so in essence Bell, the manufacturer of P-39's, had to to come up with a different airplane ? Didn't they know that the the new engine would fit without the fuse modification?

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## fubar57 (Aug 2, 2021)

They only created the illusion of a longer fuselage. It was the same length.....pay attention pulleeeze

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## SaparotRob (Aug 2, 2021)

Sorry. I'm kinda' out of my depth here.


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## fubar57 (Aug 2, 2021)

I think all of us, save one, is out of our depth here

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## GregP (Aug 2, 2021)

This thread is dedicated to all those inventive people who tried to do the impossible and succeeded. It is also dedicated to those cravers, who have the heart of crine in life. Because never before would pursuit of genius, of inventive type, with the crib of sworn-in nine. In life itself, men are said to laugh, or he has his foot in the crine sign. But in hearts anew we know, that praise of quorites is the important. Fingers of the hand are signed, in 1914.

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## Glider (Aug 2, 2021)

fubar57 said:


> I think all of us, save one, is out of our depth here


Personally I see the opposite. He dived in and then found that he was out of his depth

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## fubar57 (Aug 2, 2021)

I stand corrected


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## buffnut453 (Aug 2, 2021)

GregP said:


> This thread is dedicated to all those inventive people who tried to do the impossible and succeeded. It is also dedicated to those cravers, who have the heart of crine in life. Because never before would pursuit of genius, of inventive type, with the crib of sworn-in nine. In life itself, men are said to laugh, or he has his foot in the crine sign. But in hearts anew we know, that praise of quorites is the important. Fingers of the hand are signed, in 1914.



Have you been at the sherry again, Greg? Or was it the medicinal brandy this time?


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## P-39 Expert (Aug 2, 2021)

special ed said:


> Birch Matthews in his book, Cobra, covers the XP-39E. Three were contracted, two for flight and one structure test. The first, 41-19501 and the second 41-19502. To build the XP-39E, major portions of the wing and fuselage changed. Wingspan and root chord increased. A new center section allowed the new thicker airfoil to include two .50s in each wing, giving six .50s and the ever present 37mm. The fuselage was LENGTHENED 1.75 feet to accommodate THE LONGER Allison V-1710-E9 (-47) BECAUSE OF THE OVERALL LENGTH WITH THE AUX STAGE SUPERCHARGER. The normal gross weight came in just under 9000 pounds making it the heaviest Airacobra ever built. The first acft was used for handling qualifications with the temporary engine and crashed during spin tests after 15 hours. The second acft had the -47 engine and was used only for performance tests. A replacement third aircraft was ordered and built, 42-71464, with no armor, armament and basic radio. Although the second acft reached 393 mph, the USAAF saw no further need for the E model. All this reading is going to make me the new P-39 expert although my favorite is the P-38. I had forgotten how much data on the P-39 and variations, as well as the P-63, Matthews has collected. He actually begins the Bell story in 1934, the very beginning of the company . Our resident P-39 Expert should make this his textbook and study for a degree.


I've had that book for years, so long that the back is already out of it. It was a logical assumption that the fuselage was lengthened for the aux stage, but actually the engine section where the aux stage is located is the same size on both the P-39 and P-39E. The aft fuselage behind the bulkhead at the end of the engine section was lengthened.


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## pbehn (Aug 2, 2021)

P-39 Expert said:


> I've had that book for years, so long that the back is already out of it. It was a logical assumption that the fuselage was lengthened for the aux stage, but actually the engine section where the aux stage is located is the same size on both the P-39 and P-39E. The aft fuselage behind the bulkhead at the end of the engine section was lengthened.


Why did they lengthen the fuselage? It seems a very silly thing to do when the Aux supercharger fitted in the P-39.

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## Thumpalumpacus (Aug 2, 2021)

Milosh said:


> View attachment 635432



See? Even on land, they had to weigh down the nose due to CoG!


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## pbehn (Aug 2, 2021)

Not being an expert on the subject I am a little confused. The list of engine variants for the Allison V-1710 says that the -47 variant was an "E" model, those with the aux supercharger were F variants. Was the plane that crashed after 15 hrs flight testing fitted with the Aux supercharger?


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## GregP (Aug 2, 2021)

That was the dedication from the old movie "Gizmo." Not the critter Gizmo, but the old collection of early film clips of inventions.

If you haven't seen it, it's worth the look back at things they tried to invent since movie film came out. There are definitely some crazy things going on in that movie!

Gizmo! (1977) - IMDb


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## Greg Boeser (Aug 2, 2021)

drgondog said:


> Actually, the universe is at odds with itself re: P-39 actually being flown by 31st FG in combat. The 8th AF VC detail Victory credits have 2 P-39 victories on 19 August, 1942. Frank Olynyk (whom I trust most of historians) has Spit V and Roger Freeman has Spitfire assigned to 31st upon arrival in Britain. JG 26 Hermichen stated Aircobra for August 19th - amidst another victory claim for a Spitfire in the same area around Dieppe.
> 
> I relied on 8th AF and JG 26 as primary source but have no dog in this hunt as I have never been certain. My logic is that 350th FG conclusively were assigned P-400 that RAF did not want. ALL my sources agree that, and that it was briefly assigned to 8th AF. My father's last USAF job was Dpty COS - Missiles Div, ADC to M.Gen Sandy McCorkle - former CO of 31st. McCorkle was NOT with 31st in England, joined in 1943 as CO. That said, he 'remembered' that 1st flew Aircobra's in England before conversion to Spits.
> 
> If so, where did they go - the 350th FG?


Maybe MG McCorkle was remembering flying the P-39 in Alaska with the 54th FG. The 54th deployed in June 1942 and was withdrawn in December. McCorkle was the deputy commander and commander during this time. The unit participated in a total of nine offensive missions between 14 September and 9 October, claiming ten Japanese float planes for the loss of one. The P-39 was found to lack the range for the distances involved in the theater, and the landing gear proved not sturdy enough for the rough forward airfields in theater. The unit returned to the States where it was converted to an RTU.

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## FLYBOYJ (Aug 2, 2021)

P-39 Expert said:


> *It was a logical assumption that the fuselage was lengthened for the aux stage*


Why don't you just end with that and give it a rest.

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## FLYBOYJ (Aug 2, 2021)

pbehn said:


> Not being an expert on the subject I am a little confused. The list of engine variants for the Allison V-1710 says that the -47 variant was an "E" model, those with the aux supercharger were F variants. Was the plane that crashed after 15 hrs flight testing fitted with the Aux supercharger?


From Joe B

_"On April 10, 1941, two P-39Ds were ordered modified and flight tested under contract AC18373 as flying testbeds for the experimental Continental V-1430-1 supercharged inverted-Vee engine that was expected to deliver 2100 hp. These aircraft were assigned the designation XP-39E. The company designation was Model 23. A third machine was later added to the order as a nonflying static test example. Serials were 41-19501, 41-19502, and 41-71464. I am not sure whether these were newly-built aircraft, or modified P-39Ds that were assigned new serials.

However, the Continental engine was not yet ready when the XP-39E airframes were completed, and the 1325 hp Allison V-1710-47 engine was installed in its place. In pursuit of better high-altitude performance, the -47 engine was equipped with a two-stage supercharger and drove an Aeroproducts propeller."_

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## special ed (Aug 2, 2021)

Pbehn
Matthews says the -47 engine was not ready for the first flight of the first airframe, so a temporary engine was used until delivery of the -47 which went into the second aircraft 41-19502. The first aircraft, 41-19501, crashed after 15 hours and still had a temporary engine. The static test airframe was not serialled. The replacement,42-71464, number according to Matthews (rather than 41-71464 Baugher) may have had the -47 engine as it was not mentioned in the part I read. I would suggest reading the Matthews book for any interested because it has a lot of data and each can decide why Bell would lengthen the engine compartment unnecessarily. Since I have begun the book again, I find I overlooked many later detailed parts and tables because when I first read it I was interested in the photos and external parts of the plane for model references. I found an appendix in the back I didn't remember, detailing the markings for the P-400 Airacobra Mk.I. As to whether the P-39Es were converted Ds or not, Matthews says a contract was signed for three aircraft, one to be used for structure tests and two flying. Another contract was signed for the replacement for the crashed bird.

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## FLYBOYJ (Aug 3, 2021)

special ed said:


> Pbehn
> Matthews says the -47 engine was not ready for the first flight of the first airframe, so a temporary engine was used until delivery of the -47 which went into the second aircraft 41-19502. The first aircraft, 41-19501, crashed after 15 hours and still had a temporary engine. The static test airframe was not serialled. The replacement,42-71464, number according to Matthews (rather than 41-71464 Baugher) may have had the -47 engine as it was not mentioned in the part I read. I would suggest reading the Matthews book for any interested because it has a lot of data and each can decide why Bell would lengthen the engine compartment unnecessarily. Since I have begun the book again, I find I overlooked many later detailed parts and tables because when I first read it I was interested in the photos and external parts of the plane for model references. I found an appendix in the back I didn't remember, detailing the markings for the P-400 Airacobra Mk.I. As to whether the P-39Es were converted Ds or not, Matthews says a contract was signed for three aircraft, one to be used for structure tests and two flying. Another contract was signed for the replacement for the crashed bird.


After reading through this I think there is some confusion. From what I understand the intended engine was the Continental V-1430-1. This was the engine that wasn't ready so the V-1710-47 was installed instead. Correct me if I'm wrong.

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## P-39 Expert (Aug 3, 2021)

FLYBOYJ said:


> After reading through this I think there is some confusion. From what I understand the intended engine was the Continental V-1430-1. This was the engine that wasn't ready so the V-1710-47 was installed instead. Correct me if I'm wrong.


You are both correct. The Continental engine was not ready so the Allison-47 was chosen. The -47 wasn't quite ready so a single stage Allison-35 was installed for flight testing.


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## Shortround6 (Aug 3, 2021)

So far this could go either way, 
Vees for Victory says that the first -47 engine was in the Allison altitude test chamber in February of 1942 which makes a first flight in the XP-39E in the middle of March suspect but possible. 
It also says that Feb 1942 was when Allison started development testing of the hydraulic drive for the aux supercharger and not the single speed friction clutch drive. 

The -47 went through quite a number of specification changes so it is possible that the XP-39 flew with some sort of -47 engine but not one in the final configuration? 

Only 7 were initially contracted for, one test engine, two for the XP-39s and to for the XP-63s and two spares. Initial contract called for a 9 1/2 impeller in the aux supercharger. 

Yes the XP-39 was initially designed around the Continental V-1430-1.

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## P-39 Expert (Aug 3, 2021)

Shortround6 said:


> So far this could go either way,
> Vees for Victory says that the first -47 engine was in the Allison altitude test chamber in February of 1942 which makes a first flight in the XP-39E in the middle of March suspect but possible.
> It also says that Feb 1942 was when Allison started development testing of the hydraulic drive for the aux supercharger and not the single speed friction clutch drive.
> 
> The -47 went through quite a number of specification changes so it is possible that the XP-39 flew with some sort of -47 engine but not one in the final configuration?


You mean XP-39E, right? The -47 evolved into the -93 with the addition of the hydraulic clutch, 8.1 internal SC gear and new intake manifolds without backfire screens . 


Shortround6 said:


> Only 7 were initially contracted for, one test engine, two for the XP-39s and to for the XP-63s and two spares. Initial contract called for a 9 1/2 impeller in the aux supercharger.
> 
> Yes the XP-39 was initially designed around the Continental V-1430-1.


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## special ed (Aug 3, 2021)

Wright Field wanted a test acft for the Continental V-1430, contacted Bell to redesign the P-39 to test it. Continental then had to redesign the engine to upright configuration to fit the P-39. Matthews points out the V-1430 "was never ready for the Bell airframe or any other." Bell worked with Wright Field to develop model specs for P-39E. As of Feb 18 1941, power plant selection had not been finalized so both engines were candidates.

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## GregP (Aug 3, 2021)

Either way, the XP-39E was not a standard P-39 airframe. It is reported they tried a laminar flow wing on it, but there is no substantiation.

They tried 3 different tail surfaces on it. The fuselage was lengthened 1.75 feet (21 inches) to accommodate the V-1710-47 engine. They would not likely have done that if the Aux-stage engine had fitted without being lengthened, and subsequent P-63s all had longer fuselages, whether on not they had aux-stage engines installed. What I'm saying is there was no "short-fuselage" P-63 with a single-stage engine; it went into a standard P-63 fuselage.

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## Glider (Aug 3, 2021)

GregP said:


> Either way, the XP-39E was not a standard P-39 airframe. It is reported they tried a laminar flow wing on it, but there is no substantiation.
> 
> They tried 3 different tail surfaces on it. The fuselage was lengthened 1.75 feet (21 inches) to accommodate the V-1710-47 engine. They would not likely have done that if the Aux-stage engine had fitted without being lengthened, and subsequent P-63s all had longer fuselages, whether on not they had aux-stage engines installed. What I'm saying is there was no "short-fuselage" P-63 with a single-stage engine; it went into a standard P-63 fuselage.


I must have missed something. Weren't these supposed to be simple, obvious changes easily implemented?

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## GregP (Aug 3, 2021)

Actually, with the P-39E they were trying to materially improve the P-39. They DID manage to make it perform better at 20,000 feet and above, but still had the basic design flaws.

No range to speak of, narrow CG envelope, no room for development of the platform (little room to add anything and no excess of power if they DID). It wasn't a BAD airplane, but the existing fighters that generally outperformed it were better in almost all respects, perhaps except for climb at low altitudes. It still had the "don't pull hard on the stick quickly or you'll stall" behavior, and it didn't have all that many redeeming characteristics to make anyone who flew it choose it over the more conventional airplanes, which almost universally had better flying characteristics except for having heavier controls. Most pilots LIKED controls heavier than the P-39 controls. The stick-force-per-g was quite low, making it easy to over-pull into a hard turn. At low altitude, that would be fatal.

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## BiffF15 (Aug 3, 2021)

Glider said:


> I must have missed something. Weren't these supposed to be simple, obvious changes easily implemented?


Glider,

I think you might be missing context. There is one poster who keeps repeating incorrectly that a two stage Allison would fit in a standard P-39 airframe. One two stage Allison appears was fitted to a XP-39E (with a 21” fuselage stretch), or not a standard P-39. The P-39E also had several tail configurations fitted, which appear to have resulted in what became the P-63.

There has been some great data presented here, but required several sleuths to keep it in context and or chronology. Be careful sorting through the information lest you be led astray.

Cheers,
Biff

PS: The above assumes you are just landing in or returning to this thread. My apologies if that’s incorrect.

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## Shortround6 (Aug 3, 2021)

special ed said:


> Matthews points out the V-1430 "was never ready for the Bell airframe or any other."


One could also say that the XIV-1430 was never ready for an airframe either, it was flown but results show a far from ready engine/powerplant.

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## fubar57 (Aug 4, 2021)



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## nuuumannn (Aug 4, 2021)

BiffF15 said:


> There has been some great data presented here, but required several sleuths to keep it in context and or chronology. Be careful sorting through the information lest you be led astray.



Or, in other words...




Thanks Biff, I have been absent for a few days and this thread has, not surprisingly dredged up more stuff I didn't know...

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## GrauGeist (Aug 5, 2021)

fubar57 said:


> View attachment 636368​


Hey Geo...is it my imagination, or is that center cricket making amorous advances on the one to the left?

Asking for a friend, of course.

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## Thumpalumpacus (Aug 5, 2021)

GrauGeist said:


> Hey Geo...is it my imagination, or is that center cricket making amorous advances on the one to the left?
> 
> Asking for a friend, of course.



_Some_one got shot down!

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## XBe02Drvr (Aug 5, 2021)

GrauGeist said:


> Hey Geo...is it my imagination, or is that center cricket making amorous advances on the one to the left?
> 
> Asking for a friend, of course.


"Not tonight, Honey, I'm not in the mood!"

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## Peter Gunn (Aug 5, 2021)

GrauGeist said:


> Hey Geo...is it my imagination, or is that center cricket making amorous advances on the one to the left?
> 
> Asking for a friend, of course.


Center cricket: "Hey baby, I fly F-15's..."

Left cricket: "I don't play for that team..."

Center cricket: 

Right cricket: "Dude, you really aren't paying attention..."

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## pbehn (Aug 5, 2021)

With regards to all recent posts about the P-39E. As as I can see the original contract for the Continental engine was a development contract, it was never going to slot straight in. Once that wasnt available then the whole contract changed. The Continental 1430 was supposed to be a better high altitude engine, as was the Aux supercharged Allisson. But so was the _47 variant of the Allison. Obviously how much better they are is a big difference but when reading various histories they can all be called higher performers than the original.
Changes to the wing chord, span and tail didnt result in any substantial difference in performance so the "E" variant wasnt put into production. However, the P-39N was put into production with an even better engine from the same series of the Allisson. The Aux supercharged version was also continued with the P-63. If the P-39E ever flew with an Aux supercharged engine surely it would be much faster than the single stage Allisson engine and this would have been recorded.

As others have shown mathematically, putting the Aux supercharger in a P-39 frame would have it sitting on its tail, extending the tail by 2 ft just makes it sit heavier on its tail. I think the P-39E with the Aux supercharger didnt fly but was part of the development of the P-63. Engineering drawings without modern CGI can tell you if an engine will fit, it doesnt tell you if you can get a wrench onto all the bolt heads or if a mechanic can access all drain bolts and tighten all hoses. The P-39 had already had issues with things like this with gun access. To me the lengthening of the P-39 E airframe was just part of the P-63 story, nothing to do with the P-39.

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## nuuumannn (Aug 5, 2021)

pbehn said:


> To me the lengthening of the P-39 E airframe was just part of the P-63 story, nothing to do with the P-39.



Definitely, it's been stated here many times that the P-63 was built because that was an issue with the P-39, but someone's not taking note... Again though, if the P-39 was so good, why build the P-63, which was better?

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## Shortround6 (Aug 5, 2021)

There were two original XP-39Es plus a static airframe. 

The first XP-39E (with a single stage Allison?) crashed about a month after the first flight. The 2nd air frame was intended from the start to use the two stage engine and be used for performance tests while the 1st was to be used in determining handling qualities, armament tests and maneuvers. 
According to some accounts the static test airframe was brought up to flight standard. In any case a 3rd airframe was flown. The Performance was better than a standard P-39, but only at higher altitudes. 

Bell chief test pilot Bob Stanley in a Bell company report from May of 1942.
" At 393 miles per hour at approximately 24,000ft the XP-39E is definitely faster than the P-39D. Only in speed, however, does it surpass the latter airplane, the XP-39E is inferior to the P-39D in regards to takeoff distance, landing speed, rate of climb, ceiling and general handling qualities." 

Since the plane grossed over 9,000lbs with no real change in power until the higher (teens and low 20s ) altitudes were reached this is not surprising. 
The engine in the 2nd and 3rd XP-39Es did have an auxiliary supercharger (2nd stage) it just wasn't very good and did not have the hydraulic variable speed drive. 
26 flights had been made with the 2nd prototype by May 11th 1942. A connecting rod failed on the 27th flight and it took until June to repair the plane and flying started again in July.
Most of the flying from July to October of 1942 was concerned with propeller tests, in large part to support the P-63 program. The two remaining XP-39Es served as test beds for the two stage Allisons. 
While 4000 had been on order at one point the contracts were canceled or rewritten to P-63 contracts because the XP-39E was not living up to expectations/promises (where have we heard that before  )

The XP-39E used the some P-39D parts and assemblies like the gun bay, landing gear parts and cabin sub assembly.

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## GregP (Aug 5, 2021)

Like we said earlier, little room for development. If you managed to add anything, it didn't have extra power ready to be installed. All the Aux stage did was maintain S.L. power to higher altitudes.

As you stated just above, unsurprising results.

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## pbehn (Aug 5, 2021)

nuuumannn said:


> Definitely, it's been stated here many times that the P-63 was built because that was an issue with the P-39, but someone's not taking note... Again though, if the P-39 was so good, why build the P-63, which was better?


Well if the Bf109 and Spitfire had the engine in the middle (almost) every engine upgrade would need a completely different fuselage and wing arrangement so it would have been a different plane / type number. Much of the argument about the P-39 with an Aux supercharged engine is based on it taking to the air, I cant see that it ever did until it was a P-63. There was a huge advantage at the time to have a fuselage (or whatever) to use for mock ups and make your final drawings from what worked and what fitted, especially when you are shifting various ancillaries about in the air frame, sorting out whether things actually fit and what the effect on CoG are is more easily done on the real thing than a drawing board.


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## FLYBOYJ (Aug 5, 2021)

These were the only P-39s to really shoehorn a monster engine, but they were racers.






_
Engineers at Allison recommended that a modified Allison XV-1710-135 (E31) engine be used for the two racers. The modified engines used an increased-diameter supercharger impeller and undersized pistons to reduce cylinder wall friction. Using 140-octane Mobil aviation gasoline, they produced 2,000 horsepower at 3,200 r.p.m. with 86 inches (291 kilopascals) of manifold pressure. The high power output required that the engine be provided with a continuous injection of a precisely-measured water and ethyl/methyl alcohol solution when operating above 57 inches (193 kilopascals) of manifold pressure. An 85 gallon (322 liter) tank for the injection mixture was placed in the nose.

The increased power of the modified XV-1710-135 required that the P-39’s standard three-bladed propeller be replaced by a four-bladed unit from the P-63 Kingcobra. This was an Aeroproducts A624S constant-speed propeller with hollow steel blades. Its diameter was 11 feet, 0 inches (3.531 meters). The propeller gear reduction ratio remained the same, at 2.23:1, as did the remote gear box, at 1.8:1. 

The V-1710-E31 was longer and heavier than the -E19 because of an outboard reduction gear box. It was 17 feet, 4.00 inches (5.283 meters) long, 3 feet, 0.75 inches (0.933 meters) high, with the same 2 foot, 5.28 inch (0.744 meters) width. It weighed 1,500 pounds (680 kilograms)._




Bell P-39Q-10-BE Airacobra Archives - This Day in Aviation

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## nuuumannn (Aug 5, 2021)

pbehn said:


> Well if the Bf109 and Spitfire had the engine in the middle (almost) every engine upgrade would need a completely different fuselage and wing arrangement so it would have been a different plane / type number. Much of the argument about the P-39 with an Aux supercharged engine is based on it taking to the air, I cant see that it ever did until it was a P-63. There was a huge advantage at the time to have a fuselage (or whatever) to use for mock ups and make your final drawings from what worked and what fitted, especially when you are shifting various ancillaries about in the air frame, sorting out whether things actually fit and what the effect on CoG are is more easily done on the real thing than a drawing board.



The point's the same, a bigger supercharger didn't fit in a P-39 without serious modification, yet our friend is saying it could.
The P-39 airframe was limited in design and was very much a product of its time that couldn't be adapted to keep up with advances in powerplant design. Most of the prominent WW2 fighter designs underwent powerplant variant changes and some were fitted with entirely different engine types to their original ones. Fitting the engine where Bell did gave the P-39 built-in obsolescence. For one manufacturer to have to build an entirely new aeroplane to cater for a new engine modification to keep up with trends is extraordinarily wasteful and time-consuming within that time period.

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## Thumpalumpacus (Aug 5, 2021)

nuuumannn said:


> Fitting the engine where Bell did gave the P-39 built-in obsolescence.



Exactly the reason I said above that compared to the Spitfire, the -39 had little room for growth. Putting an engine in central necessarily limits how you can grow the airplane without major redesign; it demands airframe mods beyond sticking a bigger engine on the nose.

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## GrauGeist (Aug 5, 2021)

Why not replace the Allison with an 18 cylinder radial?

Oh wait...wrong airplane

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## ThomasP (Aug 5, 2021)

Let us not forget, though, that the 3rd P-63 prototype was originally intended to have a variant of the V-1650/Merlin. I have not been able to find the specific mark of the V-1650 they intended to use, but I have always assumed the V-1650-1. There is, however, more than enough room in terms of length for a Merlin 60 series. I wonder if they intended to lengthen the fuselage for the 3rd prototype? Fit a 4-blade prop? Would they have had to modify the structure of the aft section of the engine compartment in a similar manner to what they did for the production P-63?


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## Thumpalumpacus (Aug 5, 2021)

I guess I'll crack open a water and sit back. This should be good.

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## ThomasP (Aug 5, 2021)



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## GrauGeist (Aug 6, 2021)

The third XP-39E (41-71464) was a static test platform.
It never flew and was never intended to fly.


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## ThomasP (Aug 6, 2021)

Hey GrauGeist,

You are correct. I meant the 3rd P-63 prototype. I have edited my post above.

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## GregP (Aug 6, 2021)

You could make a 4-row 5-cylinders per row radial and use that .... or a 6-row, 3 cylinders per row ... but what's the point?

Just put in a big battery and a Tesla motor.

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## Thumpalumpacus (Aug 6, 2021)

GregP said:


> Just put in a big battery and a Tesla motor.



... preferably towards the front ...

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## GrauGeist (Aug 6, 2021)

GregP said:


> You could make a 4-row 5-cylinders per row radial and use that .... or a 6-row, 3 cylinders per row ... but what's the point?
> 
> Just put in a big battery and a Tesla motor.


Well they did put an 18 cylinder radial mid-ship in a fighter.





It actually had good flight characteristics and performance.

Although I have no idea about the nose armor, IFF and CoG.
Pretty sure it wasn't involved in the great Stewart-Warner cockpit heater conspiracy, either...

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## XBe02Drvr (Aug 6, 2021)

GrauGeist said:


> Well they did put an 18 cylinder radial mid-ship in a fighter.


Group W: Who, What, Where, When & Why??


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## ThomasP (Aug 6, 2021)

Italy, Piaggio P.119, Italy, 1939-43, don'know

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## DerAdlerIstGelandet (Aug 6, 2021)

Someone is awfully quiet now.


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## drgondog (Aug 6, 2021)

DerAdlerIstGelandet said:


> Someone is awfully quiet now.


Few folks like to hear that their baby is ugly and stupid..

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## GregP (Aug 6, 2021)

They only made one Piaggio P.119. The armistice ended its development.

Max speed was 398 mph. 1,500 hp, 9,016 lbs normal, 5,373 lbs empty. Was a fighter / dive bomber. Had 4 x 12.7 mm MG + 1 x 20 mm cannon. Ceiling was only 33,000 feet,


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## pbehn (Aug 6, 2021)

Ugly, stupid babies can be helped by sympathetic relocation of the compass.

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## GrauGeist (Aug 6, 2021)

I was having a bit of fun anonymously tossing the P.119 out there.

Truth be told, there were quite a few mid-engined projects either before or during the war. Some never made it off the drawing board while a few actually made it to the prototype stage.

Aside from Bell's P-39/P-63 and Piaggio's P.119, there was:
Koolhoven FK.55: first flew in 1938.
Messerschmitt Me509: paper only, cancelled.
Yokosuka R2Y: first flew in 1945.
Heinkel He119: first flew in 1937.

To add to the mid-engine mix, were the tandem engine tractor types that had an engine fore and aft of the cockpit (the Do335 was a push/pull, so not included):

Arsenal VG 10/20: first flew in 1945.
Kawasaki KI-64: first flew in 1943.

So Bell's design was not unique.

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## GregP (Aug 6, 2021)

Maybe the Fisher P-75 and Henschel P.75 (paper). I might add the Ilyushin Il-20 just for fun but, technically, it was a front-engine aircraft, even if it really didn't look like one. The Latecoere Late 299 has both a mid-engine and a front engine, so maybe it qualifies. So does the MC.72. The Vought XF5U-1 has mid engines but may not qualify as a conventional airplane.

Some odd airplane in all this! Makes us think, for sure!

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## Shortround6 (Aug 6, 2021)

MC 72 was more of a V-24?
Granted the front 12 cylinders drove one prop and the rear 12 cylinders drove the other. But one supercharger feed all 24 cylinders. Cockpit was way in back. Only things between the engine and the props were gearboxes.


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## GregP (Aug 6, 2021)

Yeah, I was just looking at planes that LOOK like they have a mid-engine. In the case of the Late 299, you could start and run one engine at a time, so maybe they qualify as separate engines ... and maybe not. Sort of like trying to be politically correct today.

Interesting airplane, anyway. Probably VERY interesting to fly.


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## SaparotRob (Aug 6, 2021)

I think the Fisher P-75 is a special category because, well, the manufacturer didn’t care if it worked. Right? It’s like they took one of the ideas from Bell to add to the fun. 
I’m outside on the phone so I’m even less inclined to look stuff up.


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## Thumpalumpacus (Aug 6, 2021)

SaparotRob said:


> I think the Fisher P-75 is a special category because, well, the manufacturer didn’t care if it worked. Right? It’s like they took one of the ideas from Bell to add to the fun.
> I’m outside on the phone so I’m even less inclined to look stuff up.



I had a model of their DC-9 copy after they merged with Price back in the 60s. This one was in Braniff colors:

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## buffnut453 (Aug 6, 2021)

Thumpalumpacus said:


> I had a model of their DC-9 copy after they merged with Price back in the 60s. This one was in Braniff colors:
> 
> View attachment 636669



What scale is that...it looks like a highly realistic model!

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## GregP (Aug 6, 2021)

Yeah, not usually too many holes in Graugeist's posts. The ones I added are interesting only, and none of them proved very successful. Seems as if the idea of a centrally-mounted engine was never a very good idea unless you had a specific use for it.

From a logical standpoint, if you have a 1200-pound engine out front, then adding a few hundred pounds away from the CG doesn't move things around too much. But if the same engine is ON the CG, then the rest of the airframe is relatively light, and adding a few hundred pounds away from the CG moves the CG a LOT by comparison. This seems obvious to me, but it rather obviously didn't to Bell. HE had a name in airplanes and I don't, and we know what happened ... they made almost 10,000 P-39s along with 3,300 P-63s, none of which could haul much of a load away from the fore and aft CG location. But they DID manage to get decent range from the late P-63s, at least.

Rambling ... so I'll stop ...

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## Thumpalumpacus (Aug 6, 2021)

buffnut453 said:


> What scale is that...it looks like a highly realistic model!



I think the only real goof-up was the non-laminar-flow wing on the model.


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## pbehn (Aug 6, 2021)

GregP said:


> Yeah, not usually too many holes in Graugeist's posts. The ones I added are interesting only, and none of them proved very successful. Seems as if the idea of a centrally-mounted engine was never a very good idea unless you had a specific use for it.
> 
> From a logical standpoint, if you have a 1200-pound engine out front, then adding a few hundred pounds away from the CG doesn't move things around too much. But if the same engine is ON the CG, then the rest of the airframe is relatively light, and adding a few hundred pounds away from the CG moves the CG a LOT by comparison. This seems obvious to me, but it rather obviously didn't to Bell. HE had a name in airplanes and I don't, and we know what happened ... they made almost 10,000 P-39s along with 3,300 P-63s, none of which could haul much of a load away from the fore and aft CG location. But they DID manage to get decent range from the late P-63s, at least.
> 
> ...


Putting the Griffon in a Spitfire involved 140Lbs of lead ballast in the tail, but the Griffon had over 1000BHP more than the early versions. The P-39 was already a heavy design when it first flew, adding ballast to the front of a P-39 would add to its problems.


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## GregP (Aug 6, 2021)

Perhaps, but maybe not if the power went up by 1,000 hp!

Of course, then the range would have been 71 miles with no reserve ...

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## pbehn (Aug 6, 2021)

GregP said:


> Perhaps, but maybe not if the power went up by 1,000 hp!
> 
> Of course, then the range would have been 71 miles with no reserve ...


Just slot a Griffon in and away you go. The last Griffons used on the Spiteful were rated at 2,350BHP which is between 3 to 4 times the output of the first Merlins. But in any case the P-63 just beat the Me262 and Meteor into introduction/service use by months not years.


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## SaparotRob (Aug 6, 2021)

Thumpalumpacus said:


> I had a model of their DC-9 copy after they merged with Price back in the 60s. This one was in Braniff colors:
> 
> View attachment 636669


I remember when it was fun to fly!

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## SaparotRob (Aug 6, 2021)

GregP said:


> Yeah, not usually too many holes in Graugeist's posts. The ones I added are interesting only, and none of them proved very successful. Seems as if the idea of a centrally-mounted engine was never a very good idea unless you had a specific use for it.
> 
> From a logical standpoint, if you have a 1200-pound engine out front, then adding a few hundred pounds away from the CG doesn't move things around too much. But if the same engine is ON the CG, then the rest of the airframe is relatively light, and adding a few hundred pounds away from the CG moves the CG a LOT by comparison. This seems obvious to me, but it rather obviously didn't to Bell. HE had a name in airplanes and I don't, and we know what happened ... they made almost 10,000 P-39s along with 3,300 P-63s, none of which could haul much of a load away from the fore and aft CG location. But they DID manage to get decent range from the late P-63s, at least.
> 
> ...


So the development of the P-63 was basically putting lipstick on a pig?

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## pbehn (Aug 6, 2021)

SaparotRob said:


> So the development of the P-63 was basically putting lipstick on a pig?


If you forget about the p-39 and P-63 as types, they served to keep Allisson in the engine business and Bell in the aircraft business to still be there when the war was finished.

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## Thumpalumpacus (Aug 6, 2021)

SaparotRob said:


> I remember when it was fun to fly!



When we returned to Iran from an American vacation in 1976, we flew aboard a Pan Am Clipper -- can't remember which name -- nonstop from JFK to Mehrabad in Teheran, about 17 hours in the air. Thankfully, the plane was very light, a 747 with perhaps 60 or 70 passengers, so when we kids got tired we lifted the armrests in the middle bank of seats and had a lumpy couch to sleep on.

Pre-Internet, it was about as fun as hammering an ingrown toenail.

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## SaparotRob (Aug 6, 2021)

pbehn said:


> If you forget about the p-39 and P-63 as types, they served to keep Allisson in the engine business and Bell in the aircraft business to still be there when the war was finished.


We could use an insightful award.

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## SaparotRob (Aug 6, 2021)

Thumpalumpacus said:


> When we returned to Iran from an American vacation in 1976, we flew aboard a Pan Am Clipper -- can't remember which name -- nonstop from JFK to Mehrabad in Teheran, about 17 hours in the air. Thankfully, the plane was very light, a 747 with perhaps 60 or 70 passengers, so when we kids got tired we lifted the armrests in the middle bank of seats and had a lumpy couch to sleep on.
> 
> Pre-Internet, it was about as fun as hammering an ingrown toenail.


I think my first flight was on Eastern; "The wings of Man". I wore a jacket and tie as did all the male passengers. The ladies, in their finest. I don't remember the food being so awful.

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## wuzak (Aug 6, 2021)

GrauGeist said:


> I was having a bit of fun anonymously tossing the P.119 out there.
> 
> Truth be told, there were quite a few mid-engined projects either before or during the war. Some never made it off the drawing board while a few actually made it to the prototype stage.
> 
> ...



Rolls-Royce Flying Test Bed - got to the mock-up stage.


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## pbehn (Aug 6, 2021)

SaparotRob said:


> We could use an insightful award.


I am not saying that the P-39 and P-63 were kept going for that reason, but these things do happen. In the middle of the war in 1941-43 you cant allow engine and plane manufacturers to fold and go out of business, if they do the workforce is gone in a month or two and you cant get it back The A-36 version of the P-51 was concocted for a similar reason, to keep the lines running and the skills in place.

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## GregP (Aug 6, 2021)

Not really putting lipstick on a pig. The P-63 had good combat flying qualities, decent range, and decent altitude capability.

Here's the thing, though ... so did the P-47 and P-51 that were in service. The P-51B/C were introduced around the same time as the P-63 and already had logistics chains in place along with trained mechanics and pilots. The P-63 was pretty good, but nothing that couldn't be done with existing airplanes. So, it was basically not really needed because it offered no new capabilities. 

It wasn't bad, just not a step forward from what was already being used and developed.

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## Greg Boeser (Aug 6, 2021)

Thumpalumpacus said:


> I had a model of their DC-9 copy after they merged with Price back in the 60s. This one was in Braniff colors:
> 
> View attachment 636669


In the days following 9/11, I came home from work one day to find my sons, aged 2 and 4 building block towers and then crashing this into them:





"We're playing Taliban, Dad!" they explained.
"I see." I replied. "_*Do*_* not* play this game at preschool!"

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## Thumpalumpacus (Aug 6, 2021)

SaparotRob said:


> I think my first flight was on Eastern; "The wings of Man". I wore a jacket and tie as did all the male passengers. The ladies, in their finest. I don't remember the food being so awful.



Mine was a Braniff 727 (hence my joke), and yes, in 1974, flying was an occasion and we dressed a little up for it. Neither Dad nor myself sported a tie, but a button-down long-sleeve and some fresh Levi's were _de rigeur_.

I remember the food being crummy, but that was 47 years ago and who knows what has happened to my neurons in the meantime? The only airliner meal I remember enjoying was a small steak on AA around 1990 or so. Everything else has been dogshit.

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## GrauGeist (Aug 6, 2021)

My first flight aboard a commercial was when I was 4 years old.
I remember everyone was dressed up nice, my folks and I as well as everyone else.
We were flying from Long Beach to San Francisco and I can't recall the airline we took, but it was a gorgeous silver bird, twin-engine prop job and I do beleive this was where my love for radials officially began!

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## XBe02Drvr (Aug 7, 2021)

Thumpalumpacus said:


> When we returned to Iran from an American vacation in 1976, we flew aboard a Pan Am Clipper





SaparotRob said:


> I think my first flight was on Eastern; "The wings of Man". I wore a jacket and tie as did all the male passengers. The ladies, in their finest. I don't remember the food being so awful.





Thumpalumpacus said:


> Mine was a Braniff 727


My first commercial was a Northeast Airlines DC3, MPV to BOS, the day after JFK was shot. The whole city was like a funeral parlor, black drapings everywhere.
Don't remember much except the reassuring rumble of a pair of Pratt 1830s, one of which apparently had a little slack in the governor cable, and wouldn't stay in synch. From my front row seat I could see the FO through the open cockpit door as he struggled with the prop controls and the beat vibrations ran back and forth beneath my feet. Of course I was clueless back then, but when I got back to school my physics teacher explained it all to me.

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## SaparotRob (Aug 7, 2021)

Remember Northwest Airlines? I took a flight with them ONCE and found out why it was called "Northworst".

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## XBe02Drvr (Aug 7, 2021)

SaparotRob said:


> Remember Northwest Airlines? I took a flight with them ONCE and found out why it was called "Northworst".


My ex wife and BFFL worked for Precision Airlines as a station manager when they were an Eastern Express codeshare in the bad old days of Frank Lorenzo, who crashed the whole Eastern empire. So we got her the necessary ratings and she got back on with Precision as an FO after they started back up as a Northwest Airlink. The whole company felt Northwest as a breath of fresh air after Eastern.
I worked briefly for Eastern as a simulator tech in the mid 70s, and even then, long before Lorenzo, the company culture was downright toxic, unless you were a pilot. The old Eddie Rickenbacker heritage was still alive and well.

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## SaparotRob (Aug 7, 2021)

I haven't heard the name Frank Lorenzo in years. I wasn't really aware of what was going on with them. I was sad to see a legacy airline go.


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## XBe02Drvr (Aug 7, 2021)

SaparotRob said:


> I haven't heard the name Frank Lorenzo in years. I wasn't really aware of what was going on with them. I was sad to see a legacy airline go.


For those of a younger vintage, the airline turmoils of the Reagan era are probably ancient history, but some of us remember well. Deregulation in 1978 suddenly made obsolete the business model of the entire legacy airline industry, which fairly quickly devastated the weaker members of the legacy club, made fertile ground for aggressive non-union startups, and fostered the careers of "robber barons" such as Frank Lorenzo, Carl Icahn, and the like.
The business friendly policies of the Reagan years led to the ignoring of antitrust and labor relations laws and a feeding frenzy of union busting, hostile takeovers, and the rise of the robber barons who accumulated great wealth buying ailing companies cheap, selling off assets, busting their unions, and running them as cash cows until they had sucked them dry, then liquidating them.
Frank Lorenzo started off with Trans Texas Airways, then started New York Air, acquired People Express, Continental, and Eastern, all highly leveraged and to be paid for out of the savings he would make on personnel costs. He "synergized" the operation by short term leasing aircraft back and forth between the different operating certificates without bothering to repaint the planes. I remember deadheading on an Eastern flight to pick up one of our planes mid-sequence and finding Eastern, Continental, and People Express emergency cards in the seat pocket of a plane painted in New York Air colors.
Inflight visual traffic ID in the hell hole that was Newark was a horror show. ATC would point out traffic as a "red Eastern", a "white Apple", or a "brown Continental" dependent on which company's livery was operating which company's flight. It got so Frank's pilots would check on frequency with a chuckle in their voices with their airline, flight number, and color acheme.
A longtime friend of mine who was a Continental captain was asked by his mom to get her a pass on his airlne to Honolulu and back. He refused and bought her first class tickets on United instead.

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## GregP (Aug 8, 2021)

The proud bird with the golden *ss ...

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## SaparotRob (Aug 8, 2021)

I built a model of the B-70 in my youth. It came with Continental Airlines decals.

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## XBe02Drvr (Aug 8, 2021)

GregP said:


> The proud bird with the golden *ss ...


Greg, when are you going to learn to spell?
It's "golden a$$"!

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## XBe02Drvr (Aug 8, 2021)

SaparotRob said:


> I built a model of the B-70 in my youth. It came with Continental Airlines decals.


What you got was a Valkyrie 70 SST, not the bomber version, shipped in the wrong box. Rare a$ the inverted Jenny po$tage $tamp! If you'd kept it you'd be a rich man today. Ha ha!

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## SaparotRob (Aug 8, 2021)

I think I got something for the "What annoyed you today" thread.

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## swampyankee (Aug 8, 2021)

Aah, memories. Agony Airways before they absorbed Piedmont (which wasn't bad) to become Useless Air....

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## SaparotRob (Aug 8, 2021)

Ahhh. Good old Agony Airlines. Take the bus instead.


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## GregP (Aug 8, 2021)

Sorry about the spelling. Must be due to poor toilet training as a kid.

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## pbehn (Aug 8, 2021)

SaparotRob said:


> Ahhh. Good old Agony Airlines. Take the bus instead.


I took the train instead of flying Air Ecosse, heres why, the fffing thing was slower than the train.

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## SaparotRob (Aug 8, 2021)

Looks like it's slower than the bus.


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## GregP (Aug 8, 2021)

In reality, though, those are good airplanes.

I'll certainly give you slow, though. Seems like cruise is just over 170 knots or so. About as fast as a Beech Bonanza.


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## pbehn (Aug 8, 2021)

GregP said:


> In reality, though, those are good airplanes.
> 
> I'll certainly give you slow, though. Seems like cruise is just over 170 knots or so. About as fast as a Beech Bonanza.





SaparotRob said:


> Looks like it's slower than the bus.


Well in theory an aircraft should be quicker than a train, but in UK there is so much air traffic that you fly in lanes. I flew on it twice from London HR to Teesside, the first time we flew out to the North Sea and then up the coast switching inland across Yorkshire to land at Teesside. The second time they added in a landing at Leeds/Bradford. Leeds Bradford is 55miles from Teesside we just got high enough to be tossed about in the cloud base before starting to land. The train started sooner, took less time and I could have a nice breakfast watching the world go bye. Bang on with the cruise speed, I remember the pilot, sounding like a WW2 bomber pilot on intercom announcing we were cruising at 180MPH.

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## Milosh (Aug 8, 2021)

When flying shouldn't time spent in the airport also be counted?

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## pbehn (Aug 8, 2021)

Milosh said:


> When flying shouldn't time spent in the airport also be counted?


Thats what I always did. When you have worked all around Europe you understand that a company's appointed travel agent only thinks about the country they are in, so they will propose flying to Frankfurt to visit Saarland instead of landing in Luxembourg and hiring a car. One company I worked for always wanted to fly me to Schipol then to Dusseldorf or Hanover But most of the time you are much better off flying to Schipol then driving to where you want to go in North Germany.


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## XBe02Drvr (Aug 8, 2021)

swampyankee said:


> Aah, memories. Agony Airways before they absorbed Piedmont (which wasn't bad) to become Useless Air....


Actually Useless Air preceded the Piedmont acquisition by several (5? 6?) years, and the Piedmont influx kept Useless off the rocks of bankruptcy for a few more.


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## XBe02Drvr (Aug 8, 2021)

pbehn said:


> I took the train instead of flying Air Ecosse, heres why, the fffing thing was slower than the train.


"Welcome aboard the latest innovation from Short Brothers Shipbuilders, the SD-3-30! Bringing the luxury of wide body seating to the regional airline industry, our new SD-3-30 replaces the traditional cramped small airliner cockpit with a spacious bridge, or wheelhouse if you prefer, in keeping with the nautical heritage of our company. As befits the residents of a seagoing nation, the flight sensations of the new SD-3-30 have been engineered to resemble those of the ferry boats that all Britons are accustomed to, making for a comfortable and familiar feeling ride. We hope you will enjoy the spacious and well appointed cabin, the comfortable seating, and the stellar meal service.
Thank you for flying Duckwaddle Air!

On a VFR repositioning flight, we blew past a Command Airways "tuna boat" (that had stolen our booked passengers by an earlier departure) 3/4 mile on the their left side, co-altitude, at dusk with our company logo illuminated, 80 knots of overtake, AND THE RIGHT PROP FEATHERED.
We were taxiing out of the LaGuardia commuter terminal with a "full boat" when we met them taxiing (waddling) in.

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## XBe02Drvr (Aug 8, 2021)

GregP said:


> In reality, though, those are good airplanes.
> 
> I'll certainly give you slow, though. Seems like cruise is just over 170 knots or so. About as fast as a Beech Bonanza.


We had a couple of these at the airline, but they flew over on the 121 side, where I worked as a mechanic for awhile.
170 knots is pretty optimistic unless your company has money to burn. On a hot summer day with a full boat the pilots would plan 150 knots to keep the TITs a safe margin below redline and fuel consumption reasonable.
The SD30's dash 67 engines, rated 1400+ HP were essentially identical to the 1100 HP dash 65s on our 1900s, just ran higher TITs and fuel flows, making maintenance more of an issue. Hot section overhauls were a major expense for the first years, while they tried to run the planes at flight manual speeds; then they slowed down a little and engine life improved dramatically.

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## GregP (Aug 8, 2021)

I had a friend who flew Twin Otters. He basically climbed and cruised using the TIT gauge. If it was light, he could stop shorter than a Cessna 172!

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## swampyankee (Aug 8, 2021)

S


XBe02Drvr said:


> Actually Useles Air preceded the Piedmont acquisition by several (5? 6?) years, and the
> Piedmont influx kept Useless off the rocks of bankruptcy for a few more.


I have repressed many of my memories of flying Agony and its w-named successor, Useless.

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## XBe02Drvr (Aug 9, 2021)

GregP said:


> I had a friend who flew Twin Otters. He basically climbed and cruised using the TIT gauge. If it was light, he could stop shorter than a Cessna 172!


I never got a PIC check in the Twotter, but I flew right seat on jumper drops and repositioning flights a number of times. Very versatile and flexible airplane, but slower than death and noisy as hell in the cockpit. A short and soft field takeoff is impressive, as the extended flaps tend to raise the mains off the ground first, so you're wheelbarrowing on the nose gear for a bit before you lift off and accelerate into a climb in a nose low attitude like a helicopeter or a BUFF. Those power lines at the end of the grass strip look like they're going to be in your lap until the last seconds.
Needless to say, that sort of takeoff is not approved for airline operations. Interestingly, Pilgrim's Twin Otters, Precision's Dornier 228s, and our 1900s were the only airliners approved to land on KBOS Rwy 33R, which is 2600 feet with water at both ends. Came in mighty handy on a post cold front day with a howling northwest wind and ALL arriving and departing traffic lined up for 33L.
"Clearance, MetroAir 1425 with delta, IFR Boston, ready to copy."
"MetroAir 1425, Clearance, ground stop in effect for Boston, expect update in one to one and a half hours....err...1425, can you accept 33 Right?"
"Affirmative, ready to copy."
"ATC clears MetroAir 1425 to the Boston Logan Airport via Burlington Four Departure then flight plan route, climb and maintain five thousand, expect one seven thousand ten minutes after takeoff....."

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## SaparotRob (Aug 9, 2021)




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## Milosh (Aug 11, 2021)

Did our expert run out of expertise?

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## FLYBOYJ (Aug 11, 2021)

XBe02Drvr said:


> I never got a PIC check in the Twotter, but I flew right seat on jumper drops and repositioning flights a number of times. Very versatile and flexible airplane, but slower than death and noisy as hell in the cockpit. A short and soft field takeoff is impressive, as the extended flaps tend to raise the mains off the ground first, so you're wheelbarrowing on the nose gear for a bit before you lift off and accelerate into a climb in a nose low attitude like a helicopeter or a BUFF. Those power lines at the end of the grass strip look like they're going to be in your lap until the last seconds.
> Needless to say, that sort of takeoff is not approved for airline operations. Interestingly, Pilgrim's Twin Otters, Precision's Dornier 228s, and our 1900s were the only airliners approved to land on KBOS Rwy 33R, which is 2600 feet with water at both ends. Came in mighty handy on a post cold front day with a howling northwest wind and ALL arriving and departing traffic lined up for 33L.
> "Clearance, MetroAir 1425 with delta, IFR Boston, ready to copy."
> "MetroAir 1425, Clearance, ground stop in effect for Boston, expect update in one to one and a half hours....err...1425, can you accept 33 Right?"
> ...


For a year I managed maintenance on the 3 Twin Otters operated by the USAFA. During that time I had to send all 6 engines to overhaul, rotating a rental spare engine through the 3 aircraft, very taxing as the contractor who picked up this contract was basically a trucking company that won an aircraft contract, some of the people I had to deal with were clueless. I really enjoyed this program despite the BS I had to put up with. My crew were great guys, some of the best mechanics I ever worked with.

A few months prior to me being laid off, my sister in law and her kids came up to visit me. My brother in law took this picture right when one of my birds was taxiing out to dump some cadet jumpers over the Academy.

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## FLYBOYJ (Aug 11, 2021)

One more pic, me and my crew;

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## XBe02Drvr (Aug 12, 2021)

FLYBOYJ said:


> One more pic, me and my crew;
> 
> View attachment 637571


Hey, Cadillac of the skies! A dash 300! "The beak". My experiences were in "snub nose" dash 100s. You had the "big engines", you lucky dog. -27s or -28s, right?


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## FLYBOYJ (Aug 12, 2021)

XBe02Drvr said:


> Hey, Cadillac of the skies! A dash 300! "The beak". My experiences were in "snub nose" dash 100s. You had the "big engines", you lucky dog. -27s or -28s, right?


"DASH THIRTY FOURS"


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## XBe02Drvr (Aug 12, 2021)

FLYBOYJ said:


> "DASH THIRTY FOURS"


Not familiar with those. Isnt that what the Cessna 425 used?


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## buffnut453 (Aug 12, 2021)

FLYBOYJ said:


> "DASH THIRTY FOURS"



Now you're just showing off!

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## special ed (Aug 12, 2021)

Any shots of the aircraft color scheme for modellers?


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## FLYBOYJ (Aug 12, 2021)

XBe02Drvr said:


> Not familiar with those. Isnt that what the Cessna 425 used?


Don't know, we went from -28s to -34s around 2007, similar to Viking's -300









DHC-6 Twin Otter


In 1965, De Havilland Canada developed the DHC-6 Twin Otter aircraft – a high winged, un-pressurized twin engine turbine powered aircraft with fixed tricycle land gear. Designed as a rugged Short Take Off and Landing (“STOL”) commuter, the Twin Otter was capable of carrying passengers and cargo...




www.vikingair.com






buffnut453 said:


> Now you're just showing off!

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## FLYBOYJ (Aug 12, 2021)

special ed said:


> Any shots of the aircraft color scheme for modellers?



















There are numerous on line, look up "UV-18 Twin Otter." The USAFA had one bird painted in a commemorative D-Day scheme

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## Glider (Aug 12, 2021)

There better looking than the P39

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## vikingBerserker (Aug 12, 2021)

Well, you say that now but wait until you remove the nose armor................

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## Glider (Aug 12, 2021)

vikingBerserker said:


> Well, you say that now but wait until you remove the nose armor................


Simple, the nose wheel goes to the rear

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## pbehn (Aug 12, 2021)

There was a long discussion a while back about range, and the requirements for forming up etc on bomber escort. I found this here MUSTANG VARIANTS OF THE RAF AND RAAF - Mustang: Thoroughbred Stallion of the Air discussing how the Mustang I was used by the RAF, once across the coast they changed course every six minutes at 275MPH cruising speed. 

27. If the desired target destruction and damage is to be secured with minimum casualties, then very careful training alone is not enough – it must be supplemented with the most careful planning. Requests for “hurry-up” or “flash” missions will have to be ignored and only those missions attempted in which there is time available for planning all details or complete “laying on” of the mission in which no details are slighted.

28. An experienced unit with all facilities available can “lay on” a mission in 1½ hrs including the briefing. They have more or less control over their target selection since their effort is unsupported and requires no coordination other than in a general way. Their targets are chosen by information contained in photographs, by information obtained from previous missions and by a general knowledge of the transportation system of a given locality.

29. Once a target is decided upon – for instance a certain area where there are several important rail lines and perhaps a canal – all the latest intelligence is made available. This includes flak maps, radar locations, locations of airfields, fighter strength and disposition, knowledge of other friendly simultaneous action, etc. The number of aircraft is set and those pilots alerted. Those pilots do not leave the post after being alerted nor are they allowed to drink – They are sent to bed early.

30. The points of entry into enemy territory by the various flights are carefully chosen with regard to the flak map, the air defense warning system, enemy fighters and target proximity and coverage. Separate zig-zag courses of approximately 6 min. length at 275 mph are planned so as to give the maximum coverage in the target area without the separate flights interfering with each other or crossing the path already covered by another fighter (in this case a flight is assumed to be the smallest unit – two abreast). Every element which will contribute to the surprise of each flight is taken into consideration. The distance to be covered by each flight in enemy territory is usually in the neighborhood of 90 miles for reach flight. The points of exit are chosen with regard to the exit points and the route home plotted on the overlay.

31. The course for the mission for any one flight consists of a number of legs of varying distances and directions. At the early morning briefing, the pilots are allowed to do most of the work in obtaining the data for his particular flight. One pilot will measure all the distances with another checking. Another pilot will obtain all the true tracks with proper checking. All the data is entered on a form 433-A and from the last minute meteorological report and the compass card of each airplane, the pilots work out their magnetic courses, true airspeeds and times. All times, airspeeds and directions will be the same from the base to the dispersal point (50-60 miles from the coast), but different for the individual flights over enemy territory and then the same again (usually) for the trip home from the rendezvous point. Gun cameras in the left landing light location take pictures of all action and verify claims.

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## XBe02Drvr (Aug 12, 2021)

Glider said:


> There better looking than the P39


Aww, c'mon man, how can you mouth such heresy?


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## special ed (Aug 12, 2021)

FLYBOYJ
Thanks for these. Looking on line for more UV-18B @ USAFA. Curiosity makes me ask why they carry both USAF and civil registration?


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## DerAdlerIstGelandet (Aug 12, 2021)

Awfully quiet in here...


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## special ed (Aug 12, 2021)

I could look up sources and bring back the Bell X-5 argument. Naah, I like the quiet and peace.

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## Thumpalumpacus (Aug 12, 2021)

Turn for the better with the DH discussion.

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## special ed (Aug 12, 2021)

I would be a poor leader and decision maker. I like the mossie and since they were being built in Canada, I would buy theirs. Shorter delivery route. After all, we did buy Avro Canada Ansons, built by Federal of Canada as AT-20 bombing trainers. Forty nine as I remember.

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## Thumpalumpacus (Aug 12, 2021)

special ed said:


> I could look up sources and bring back the Bell X-5 argument. Naah, I like the quiet and peace.



The Yeager interview I watched yesterday, the General made mention of Bell's issues with test-pilots and how that gave the USAF an opening to control several X-programs from Bell.

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## FLYBOYJ (Aug 12, 2021)

special ed said:


> FLYBOYJ
> Thanks for these. Looking on line for more UV-18B @ USAFA. Curiosity makes me ask why they carry both USAF and civil registration?


"464" and "465" carried N numbers since the time they were purchased by the USAF. "835" was operated by the US Army and was acquired in the late 1980s (I believe) and did not receive an N number when delivered. When I was on the program there was always talk of doing a conformity inspection on 835 and give it an N number. These aircraft would be considered "Public Use" and "may" be inspected by the FAA - never officially spoken but I think the USAF wanted that so a layer of oversight was built in as it was accepted these would always be contractor maintained.

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## GregP (Aug 12, 2021)

OK. Since you want controversy, which is better looking, a P-39 or this:






Hint: It was used in the 1942 movie," Flying Tigers."

Personally, I think almost anything looks better than this thing, maybe even a PZL Zubr!

Zubr:
https://i.pinimg.com/originals/82/ce/94/82ce94aa6316b4fdc11053612a2116e9.jpg

Maybe even this:





Which looks like a deranged Irish Wolfhound mated with a spider monkey.

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## GrauGeist (Aug 12, 2021)

The XC-12's windscreen configuration seemed to be a popular design feature in the late 20's and early 30's, too.

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## pbehn (Aug 12, 2021)

GregP said:


> OK. Since you want controversy, which is better looking, a P-39 or this:
> 
> View attachment 637704


You must be joking that is a nascent Concorde, onwards and upwards.

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## SaparotRob (Aug 13, 2021)

GregP said:


> OK. Since you want controversy, which is better looking, a P-39 or this:
> 
> View attachment 637704
> 
> ...


I love the Safety Plane. Why use riveted panels when you could use screws? 
That might be the first plane I ever tried to research on Wiki. I had to know if it was real or not.

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## GrauGeist (Aug 13, 2021)

SaparotRob said:


> I love the Safety Plane. Why use riveted panels when you could use screws?
> That might be the first plane I ever tried to research on Wiki. I had to know if it was real or not.


If you spot an aircraft in a movie you want to check out, head over to the Internet Movie Plane Database.
Chances are, you'll find it there.
The Internet Movie Plane Database

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## SaparotRob (Aug 13, 2021)

Thanks GrauGeist! I'll use the the site to check the "P-40's" used on the ground in The Flying Tigers. They were powered by V-8 engines and could taxi. Now to find out the truth of that.


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## Darthtabby (Aug 13, 2021)

Hope people don't mind if I throw in a quick P-39 related question here: did the P-400 variant have provision for bombs and/or drop tanks? And if so was the capability factory installed or was it more of a field modification?


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## buffnut453 (Aug 13, 2021)

Darthtabby said:


> Hope people don't mind if I throw in a quick P-39 related question here: did the P-400 variant have provision for bombs and/or drop tanks? And if so was the capability factory installed or was it more of a field modification?



This image would suggest they could at least carry a drop tank (Bell P-39 Airacobra - Wikipedia):


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## XBe02Drvr (Aug 13, 2021)

buffnut453 said:


> This image would suggest they could at least carry a drop tank (Bell P-39 Airacobra - Wikipedia):
> 
> View attachment 637721


That looks like the big "pancake" ferry tank. Were those things droppable, or bolt-ons?


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## buffnut453 (Aug 13, 2021)

XBe02Drvr said:


> That looks like the big "pancake" ferry tank. Were those things droppable, or bolt-ons?



Dunno, but here's another pic in case it's of use:


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## XBe02Drvr (Aug 13, 2021)

buffnut453 said:


> Dunno, but here's another pic in case it's of use:
> 
> View attachment 637733


Nope, that's an actual drop tank. Thanks for the pic.


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## drgondog (Aug 13, 2021)

SaparotRob said:


> I love the Safety Plane. Why use riveted panels when you could use screws?
> That might be the first plane I ever tried to research on Wiki. I had to know if it was real or not.


Screws are a.) heavier (steel vs aluminum), and b.) usually 'overkill' re; Shank dia/shear stress allowable relative to the skin, c.) labor intensive to install, d.) more chance of 'backing out' due to vibration and flex of ribs and skin. A typical 'screw' installation is a nutplate which is ridiculously overweight re; AN bucked rivet. 

95% of sheet metal installations over rib/bulkhead are structural shear panels designed to help absorb and transfer loads and should be 'permanent'.

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## Peter Gunn (Aug 13, 2021)

Glider said:


> There better looking than the P39


Eye of the beholder, I think the P-39 is one of the top 5, maybe even top 3 of the best looking fighters of WWII.

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## vikingBerserker (Aug 13, 2021)

I agree, and always liked the car door

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## buffnut453 (Aug 13, 2021)

vikingBerserker said:


> I agree, and always liked the car door



You probably wouldn't like it so much if you had to bail out of one.

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## SaparotRob (Aug 13, 2021)

buffnut453 said:


> You probably wouldn't like it so much if you had to bail out of one.


I like the door too. I truly doubt I’ll ever have to bail out of one. I don’t let reality bother me too much.

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## Thumpalumpacus (Aug 13, 2021)

vikingBerserker said:


> I agree, and always liked the car door



Now if only they had put in a cupholder and cell-phone charger.

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## SaparotRob (Aug 13, 2021)

Thumpalumpacus said:


> Now if only they had put in a cupholder and cell-phone charger.


Now you’re talking!

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## GregP (Aug 13, 2021)

I thought it had 2 USB ports, a cupholder, and a filing cabinet drawer behind the pilot seat for the weight and balance documents. A CD player was a field-installed luxury. Most had RainX wipes in a glove box, too.

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## SaparotRob (Aug 13, 2021)

GregP said:


> I thought it had 2 USB ports, a cupholder, and a filing cabinet drawer behind the pi9lot seat for the weight and balance documents. A CD player was a field-installed luxury. Most had RainX wipes in a glove box, too.


The things one learns here.


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## GrauGeist (Aug 13, 2021)

At least Galland had a cigar lighter in his.

Oh wait, we call those "power points" now days...

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## XBe02Drvr (Aug 13, 2021)

drgondog said:


> Screws are a.) heavier (steel vs aluminum), and b.) usually 'overkill' re; Shank dia/shear stress allowable relative to the skin, c.) labor intensive to install, d.) more chance of 'backing out' due to vibration and flex of ribs and skin.


And:
e.) subject to dissimilar metals corrosion over time or in a marine environment.



drgondog said:


> re; Shank dia/shear stress allowable relative to the skin


To those of us who aren't engineers:
An aluminum rivet in an aluminum skin will have similar resistance to distortion, and when stressed to the point of flexing, will "share" the stress, each yielding a tiny amount and minimizing the concentration of stress at any one point. A steel screw in an aluminum skin has almost no "give", forcing the aluminum to do all the yielding and increasing the risk of failure. One failed fastener point tends to put heavier loads on adjoining points, leading to a "zipper" type failure.

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## SaparotRob (Aug 13, 2021)

Which is why "Safety Plane" is such a great name for it.

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## Peter Gunn (Aug 13, 2021)

SaparotRob said:


> Which is why "Safety Plane" is such a great name for it.


Is that like the "Safety Dance"?

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## pbehn (Aug 13, 2021)

Peter Gunn said:


> Is that like the "Safety Dance"?


More like a safety match.

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## GrauGeist (Aug 13, 2021)

Peter Gunn said:


> Is that like the "Safety Dance"?


Only for Men Without Hats

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## Thumpalumpacus (Aug 13, 2021)

Peter Gunn said:


> Is that like the "Safety Dance"?

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## fubar57 (Aug 13, 2021)

Speaking of stripping off armour, I found this here. The P-39 Airacobra - Warfare History Network

“Nothing could touch a P-39 used below 15,000-feet” contended American Air Ace Lt. Col. William A. Shomo who flew P-39s, P-40s, F-6Ds, and a P-51D in WWII. He wouldn’t have hesitated to have even taken on the vaunted P-38 at lower altitudes because of the extreme maneuverability of the “Flying Cannon.” And it could tangle successfully with a Japanese Zero, he argued, if the American pilot kept his airspeed at 300 miles per hour or better so the enemy “couldn’t turn inside you.”

The Americans in the field experimented with the aircraft throughout the war to continually gain an edge and some additional speed, eventually stripping off a chunk of belly armor under the seat that weighed some 750 pounds. With those modifications, the P-39 could “fly like a bumble bee,” asserted Shomo. He and his men especially liked the stinging power of the plane’s 37mm cannon that could, if necessary, fire off some 30 rounds in 12 seconds. The hefty warhead had a definite arching trajectory, but one could eventually learn to “drop the shell right into someone’s shirt pocket as he walked along the beach,” said the ace."

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## pbehn (Aug 13, 2021)

Did they produce shells that were fused to explode in shirt pockets?


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## GrauGeist (Aug 13, 2021)

pbehn said:


> Did they produce shells that were fused to explode in shirt pockets?


Shirt pockets, perhaps.
Watch pockets, on the otherhand, is more complicated.

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## FLYBOYJ (Aug 13, 2021)

fubar57 said:


> Speaking of stripping off armour, I found this here. The P-39 Airacobra - Warfare History Network
> 
> “Nothing could touch a P-39 used below 15,000-feet” contended American Air Ace Lt. Col. William A. Shomo who flew P-39s, P-40s, F-6Ds, and a P-51D in WWII. He wouldn’t have hesitated to have even taken on the vaunted P-38 at lower altitudes because of the extreme maneuverability of the “Flying Cannon.” And it could tangle successfully with a Japanese Zero, he argued, if the American pilot kept his airspeed at 300 miles per hour or better so the enemy “couldn’t turn inside you.”
> 
> The Americans in the field experimented with the aircraft throughout the war to continually gain an edge and some additional speed, eventually stripping off a chunk of belly armor under the seat that weighed some 750 pounds. With those modifications, the P-39 could “fly like a bumble bee,” asserted Shomo. He and his men especially liked the stinging power of the plane’s 37mm cannon that could, if necessary, fire off some 30 rounds in 12 seconds. The hefty warhead had a definite arching trajectory, but one could eventually learn to “drop the shell right into someone’s shirt pocket as he walked along the beach,” said the ace."


This sounds like the cornerstone of "The Expert's" argument, but the article doesn't mention that Shomo became an ace flying an F-6D

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## fubar57 (Aug 13, 2021)

Maybe the Japanese wore these

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## 33k in the air (Aug 13, 2021)

fubar57 said:


> And it could tangle successfully with a Japanese Zero, he argued, if the American pilot kept his airspeed at 300 miles per hour or better so the enemy “couldn’t turn inside you.”



The same could be said for other American fighters as well, since testing of the Zero recovered from the Aleutians revealed its controls became stiff at speeds over 300 mph.

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## Thumpalumpacus (Aug 13, 2021)

GregP said:


> I thought it had 2 USB ports, a cupholder, and a filing cabinet drawer behind the pilot seat for the weight and balance documents. A CD player was a field-installed luxury. Most had RainX wipes in a glove box, too.



Is it true that the throttle was the pedal on the far right?


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## fubar57 (Aug 13, 2021)

Thumpalumpacus said:


> Is it true that the throttle was the pedal on the far right?


Yes and in place of the regular throttle quadrant was a manual 4-speed stick shift; another of those pesky British requirements that played havoc to U.S. aviators when the aircraft were returned

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## Thumpalumpacus (Aug 13, 2021)

fubar57 said:


> Yes and in place of the regular throttle quadrant was a manual 4-speed stick shift; another of those pesky British requirements that played havoc to U.S. aviators when the aircraft were returned



Dude, you gotta like a stick-shift airplane, except for yawing left when you engage the clutch.

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## pbehn (Aug 13, 2021)

Early Spitfires used the "stick shift" to raise and lower the wheels. It resulted in them waddling up into the sky like a troop of drunken ducks.

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## GregP (Aug 13, 2021)

I have also read Shomo's account of liking the P-39. It didn't show up in the actual scores of USAAF pilots in the Pacific, though. I have read three or four accounts of loving the P-39, none of the authors of which seemed to do very well in it.

Makes me wonder, but not exactly doubt they liked the P-39. There's usually ONE in the neighborhood with a plaster lawn jockey or pink flamingos in the yard.

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## pbehn (Aug 13, 2021)

fubar57 said:


> The Americans in the field experimented with the aircraft throughout the war to continually gain an edge and some additional speed, *eventually stripping off a chunk of belly armor under the seat that weighed some 750 pounds*. With those modifications, the P-39 could “fly like a bumble bee,” asserted Shomo. He and his men especially liked the stinging power of the plane’s 37mm cannon that could, if necessary, fire off some 30 rounds in 12 seconds. The hefty warhead had a definite arching trajectory, but one could eventually learn to “drop the shell right into someone’s shirt pocket as he walked along the beach,” said the ace."


This is what my daughter would call a "random" argument, she has a different way of using English, it means crazy and illogical. If removing 750Lbs of armour made it a world beater who was the fool who put the 750Lbs of armour there in the first place? Reading the various variant types in Wiki, some have additional belly armour, but it is there for a reason. Obviously removing belly armour improves performance and the ones who aren't taken down by ground fire will say they had a better performing airplane.

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## fubar57 (Aug 13, 2021)

One day I'll find the book or website that had a quote from a pilot in the Pacific that said that they deliberately "accidentally" sabotaged their P-39s so that they could get newer P-38s. Not being a pilot but having slept in a Holiday Inn.....twice....I thought pilots needed additional twin engine time before they fly them. The quote, it seems to me, would be unlikely in a combat zone

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## Thumpalumpacus (Aug 13, 2021)

The other thing is -- what fighter plane has 10% of its gross weight devoted to one single slab of armor?

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## pbehn (Aug 13, 2021)

fubar57 said:


> One day I'll find the book or website that had a quote from a pilot in the Pacific that said that they deliberately "accidentally" sabotaged their P-39s so that they could get newer P-38s. Not being a pilot but having slept in a Holiday Inn.....twice....I thought pilots needed additional twin engine time before they fly them. The quote, it seems to me, would be unlikely in a combat zone


I just read recently on here that pilots in N Africa suffered regardless of experience trying to transition from Hurricanes to P-40s while in combat. The idea that you can just jump out of a P-39 and into a P-38 and be more effective is just silly. 

I havnt slept in a Holiday Inn, but I did stay at the Skean Dhu at Aberdeen airport which qualifies me for all helicopter and light aircraft operations.

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## GrauGeist (Aug 13, 2021)

I slept overnight at the Leonardo DaVinci airport on a bench upstairs by the vending machines, so let me weigh in 

I beleive the P-39 pilots transitioning to the P-38 would have been familiarized with an advanced twin trainer where possible, even if it was the local hack in forward areas.
I really wish my Uncle Jimmy were still with us, as he went from a P-36 to a P-39 and then to a P-38 (which he flew for the duration) and he'd have been able to provide details of the process.

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## DerAdlerIstGelandet (Aug 13, 2021)

So what does overnighting on the floor of Laguardia qualify me as?

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## DerAdlerIstGelandet (Aug 13, 2021)

GregP
how far is the museum from Palmdale?


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## Greg Boeser (Aug 13, 2021)

I doubt it. Probably just a bit of ground school, cockpit familiarization and then let 'em at it.
According to John Stanaway in _Attack and Conquer, the 8th Fighter Group in World War II, _the 80th Fighter Squadron, the first squadron in the group to transition to the P-38, and third overall in NG, was pulled from the frontline in late January, 1943 spent about two months reorganizing and transitioning, before returning to combat at the end of March. Sadly, he does not detail the training involved.


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## FLYBOYJ (Aug 13, 2021)

Greg Boeser said:


> I doubt it. Probably just a bit of ground school, cockpit familiarization and then let 'em at it.
> According to John Stanaway in _Attack and Conquer, the 8th Fighter Group in World War II, _the 80th Fighter Squadron, the first squadron in the group to transition to the P-38, and third overall in NG, was pulled from the frontline in late January, 1943 spent about two months reorganizing and transitioning, before returning to combat at the end of March. Sadly, he does not detail the training involved.


Read "Peter Three Eight" by Stanaway, he goes into early P-38 ops in NG in detail

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## tyrodtom (Aug 13, 2021)

fubar57 said:


> Speaking of stripping off armour, I found this here. The P-39 Airacobra - Warfare History Network
> 
> “Nothing could touch a P-39 used below 15,000-feet” contended American Air Ace Lt. Col. William A. Shomo who flew P-39s, P-40s, F-6Ds, and a P-51D in WWII. He wouldn’t have hesitated to have even taken on the vaunted P-38 at lower altitudes because of the extreme maneuverability of the “Flying Cannon.” And it could tangle successfully with a Japanese Zero, he argued, if the American pilot kept his airspeed at 300 miles per hour or better so the enemy “couldn’t turn inside you.”
> 
> The Americans in the field experimented with the aircraft throughout the war to continually gain an edge and some additional speed, eventually stripping off a chunk of belly armor under the seat that weighed some 750 pounds. With those modifications, the P-39 could “fly like a bumble bee,” asserted Shomo. He and his men especially liked the stinging power of the plane’s 37mm cannon that could, if necessary, fire off some 30 rounds in 12 seconds. The hefty warhead had a definite arching trajectory, but one could eventually learn to “drop the shell right into someone’s shirt pocket as he walked along the beach,” said the ace."


the il-2 had a 1500 lb armored tub around the cockpit and engine area. doesn't 750 lbs just under the P-39's seat sound a little doubtful ?
this thread does seem haunted by misprints.

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## GrauGeist (Aug 13, 2021)

We actually have a thread here on the forum where a member had various P-39 armor pieces in his collection, plus there is a posted chart with with weights, measures and placement by variant.

It appears the total average weight for a P-39's armor was roughly 256 pounds.

See it here:
P-39 Airacobra armor

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## BiffF15 (Aug 13, 2021)

DerAdlerIstGelandet said:


> So what does overnighting on the floor of Laguardia qualify me as?


A survivor. Don’t be afraid of COVID 19 after that experience.

The old terminal was like a third world single wide trailer inside with garbage cans to catch rainwater.

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## DerAdlerIstGelandet (Aug 13, 2021)

BiffF15 said:


> A survivor. Don’t be afraid of COVID 19 after that experience.
> 
> The old terminal was like a third world single wide trailer inside with garbage cans to catch rainwater.



I will not lie. Once the last bar in the terminal closed it was a terrible experience.

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## GregP (Aug 14, 2021)

Hey Der Adler. It is about 80 miles or 1.5 hours or so, not during rush hours.

I'd love to get a visit, and you could stay at my house, if need be, overnight. I'm about 2 - 3 miles from Chino airport.

We could see MANY warbirds, have some B-B-Q, and quaff a few beers, in no particular order.

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## DerAdlerIstGelandet (Aug 14, 2021)

GregP said:


> Hey Der Adler. It is about 80 miles or 1.5 hours or so, not during rush hours.
> 
> I'd love to get a visit, and you could stay at my house, if need be, overnight. I'm about 2 - 3 miles from Chino airport.
> 
> We could see MANY warbirds, have some B-B-Q, and quaff a few beers, in no particular order.



PM sent.


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## Greg Boeser (Aug 14, 2021)

FlyboyJ,
Cool. Thanks for the tip.

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## XBe02Drvr (Aug 14, 2021)

DerAdlerIstGelandet said:


> So what does overnighting on the floor of Laguardia qualify me as?


A doormat.

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## XBe02Drvr (Aug 14, 2021)

BiffF15 said:


> The old terminal was like a third world single wide trailer inside with garbage cans to catch rainwater.


So what's the "new" terminal like? My memories are all of the 3rd world single wide.

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## BiffF15 (Aug 14, 2021)

XBe02Drvr said:


> So what's the "new" terminal like? My memories are all of the 3rd world single wide.


It’s a very nice terminal now. High ceilings, lots of food choice, bars (most still closed) but a vast improvement. It does follow the newer configuration of the security flow dumping you into the shopping area.

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## XBe02Drvr (Aug 14, 2021)

BiffF15 said:


> It’s a very nice terminal now. High ceilings, lots of food choice, bars (most still closed) but a vast improvement. It does follow the newer configuration of the security flow dumping you into the shopping area.


Last time I was there was in 2017 when Kathleen checked out on retirement day. Construction in progress and we walked through a rabbit warren maze of passageways to various AA offices and ops spaces, many looking like they were temporary. Glad they made something nice of it. Now if they could just fix the airside.

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## SaparotRob (Aug 14, 2021)

Any consideration of extending the flight deck of U.S.S. LaGuardia?

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## XBe02Drvr (Aug 14, 2021)

SaparotRob said:


> Any consideration of extending the flight deck of U.S.S. LaGuardia?


Hell yes! All you'd have to do is fill in Flushing Bay, fill and channelize the East River all the way to the Throgs Neck, extend parallel causeways to Riker's Island, move the prisons out to Hart Island, and relocate all the housing from College Point, and you could have JFK North. No sweat, piece of cake. Robert Moses and Fiorello LaGuardia would be so proud!
NY TRACON would have a heart attack.

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## P-39 Expert (Aug 15, 2021)

fubar57 said:


> Speaking of stripping off armour, I found this here. The P-39 Airacobra - Warfare History Network
> 
> “Nothing could touch a P-39 used below 15,000-feet” contended American Air Ace Lt. Col. William A. Shomo who flew P-39s, P-40s, F-6Ds, and a P-51D in WWII. He wouldn’t have hesitated to have even taken on the vaunted P-38 at lower altitudes because of the extreme maneuverability of the “Flying Cannon.” And it could tangle successfully with a Japanese Zero, he argued, if the American pilot kept his airspeed at 300 miles per hour or better so the enemy “couldn’t turn inside you.”
> 
> The Americans in the field experimented with the aircraft throughout the war to continually gain an edge and some additional speed, eventually stripping off a chunk of belly armor under the seat that weighed some 750 pounds. With those modifications, the P-39 could “fly like a bumble bee,” asserted Shomo. He and his men especially liked the stinging power of the plane’s 37mm cannon that could, if necessary, fire off some 30 rounds in 12 seconds. The hefty warhead had a definite arching trajectory, but one could eventually learn to “drop the shell right into someone’s shirt pocket as he walked along the beach,” said the ace."


I have read about this 750lb piece of armor before but never seen it listed in any weight table. That's a lot of weight, equivalent to a 110gal drop tank full of fuel. The effect on performance must have been huge. I really doubt these actually existed.

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## wuzak (Aug 15, 2021)

It looks like we were all so wrong about the P-39, it dominated German fighters, as shown in this documentary

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## FLYBOYJ (Aug 15, 2021)

P-39 Expert said:


> I have read about this 750lb piece of armor before but never seen it listed in any weight table. That's a lot of weight, equivalent to a 110gal drop tank full of fuel. The effect on performance must have been huge.* I really doubt these actually existed.*


*So the person interviewed, Lt. Col. William A. Shomo, a 26 year Air Force veteran, Medal of Honor Winner (with 6 kills in one mission) with several thousand flight hours in various combat aircraft (to include the P-39) is just making this up?!?!? But you "read" about this?????





*


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## ThomasP (Aug 15, 2021)

I have read  that the additional belly armour was only fitted in the recon model. It was made of aluminum, and IIRC it was about 3' x 4' and weighed 75 lbs. Also IIRC it was located about where the outline shows it in the image below.

edit: added the image below

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## P-39 Expert (Aug 15, 2021)

FLYBOYJ said:


> *So the person interviewed, Lt. Col. William A. Shomo, a 26 year Air Force veteran, Medal of Honor Winner (with 6 kills in one mission) with several thousand flight hours in various combat aircraft (to include the P-39) is just making this up?!?!? But you "read" about this?????
> 
> View attachment 637920
> *


So show me the 750lb piece of armor. All the rest of the armor on the plane weighed about 250lbs. Didn't say Shomo was incorrect. The writer may have been mistaken.

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## drgondog (Aug 15, 2021)

fubar57 said:


> Speaking of stripping off armour, I found this here. The P-39 Airacobra - Warfare History Network
> 
> “Nothing could touch a P-39 used below 15,000-feet” contended American Air Ace Lt. Col. William A. Shomo who flew P-39s, P-40s, F-6Ds, and a P-51D in WWII. He wouldn’t have hesitated to have even taken on the vaunted P-38 at lower altitudes because of the extreme maneuverability of the “Flying Cannon.” And it could tangle successfully with a Japanese Zero, he argued, if the American pilot kept his airspeed at 300 miles per hour or better so the enemy “couldn’t turn inside you.”
> 
> The Americans in the field experimented with the aircraft throughout the war to continually gain an edge and some additional speed, eventually stripping off a chunk of belly armor under the seat that weighed some 750 pounds. With those modifications, the P-39 could “fly like a bumble bee,” asserted Shomo. He and his men especially liked the stinging power of the plane’s 37mm cannon that could, if necessary, fire off some 30 rounds in 12 seconds. The hefty warhead had a definite arching trajectory, but one could eventually learn to “drop the shell right into someone’s shirt pocket as he walked along the beach,” said the ace."


And yet Shomo flew P-39Qs for a year with zero VC. All his scores came flying the F-6D (7 total. 6 in one mission). I'm wondering where he developed his successful engagement skills versus the Zero.

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## Thumpalumpacus (Aug 15, 2021)

P-39 Expert said:


> So show me the 750lb piece of armor. All the rest of the armor on the plane weighed about 250lbs.



I'd be willing to bet "750" lbs is a typo for 75 lbs.

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## DerAdlerIstGelandet (Aug 15, 2021)

FLYBOYJ said:


> *So the person interviewed, Lt. Col. William A. Shomo, a 26 year Air Force veteran, Medal of Honor Winner (with 6 kills in one mission) with several thousand flight hours in various combat aircraft (to include the P-39) is just making this up?!?!? But you "read" about this?????
> 
> View attachment 637920
> *



Aka...

He’s just a joe pilot...

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## P-39 Expert (Aug 15, 2021)

ThomasP said:


> I have read  that the additional belly armour was only fitted in the recon model. It was made of aluminum, and IIRC it was about 3' x 4' and weighed 75 lbs. Also IIRC it was located about where the outline shows it in the image below.
> 
> edit: added the image below
> View attachment 637932


This makes a lot more sense.

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## GrauGeist (Aug 15, 2021)

Thumpalumpacus said:


> I'd b willing to bet "750" lbs is a typo for 75 lbs.


I'm thinking along these lines, too.
One of the heaviest pieces of armor was the nose armor, that ranged between 70 to 95 pounds, depending on the variant.

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## FLYBOYJ (Aug 15, 2021)

P-39 Expert said:


> So show me the 750lb piece of armor. All the rest of the armor on the plane weighed about 250lbs. Didn't say Shomo was incorrect. *The writer may have been mistaken.*


*THEN SAY THAT TO BEGIN WITH!!!! 





*


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## FLYBOYJ (Aug 15, 2021)

drgondog said:


> And yet Shomo flew P-39Qs for a year with zero VC. All his scores came flying the F-6D (7 total. 6 in one mission). I'm wondering where he developed his successful engagement skills versus the Zero.


I believe it was documented that Shomo and his wing man (Lieutenant Paul Lipscomb) may have come across a flight of very green pilots on a training mission, thus the lack of aggressiveness of the fighters, IIRC 3 of the Japanese fighters actually fled the engagement.


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## swampyankee (Aug 15, 2021)

Thumpalumpacus said:


> I'd be willing to bet "750" lbs is a typo for 75 lbs.


Likely correct. Steel armor one inch thick weighs about forty pounds per square foot. Seven-hundred fifty pounds of armour 0.25 in thick -- which is thick for aircraft armor -- would cover 75 square feet, far larger than likely.

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## SaparotRob (Aug 15, 2021)

FLYBOYJ said:


> I believe it was documented that Shomo and his wing man (Lieutenant Paul Lipscomb) may have come across a flight of very green pilots on a training mission, thus the lack of aggressiveness of the fighters, IIRC 3 of the Japanese fighters actually fled the engagement.


A win is a win.

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## GrauGeist (Aug 15, 2021)

The Hs129's armored bathtub and windscreen weighed over a ton and ranged from 1/4" to 1/2" in it's construction (windscreen was almost 3" thick).

So figure the P-39's 256 pounds of standard armor plus the alleged 750 pound belly armor would put it at roughly half the weight of the Hs129's armor.

That's a hell of alot of weight...

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## fubar57 (Aug 15, 2021)

What if you just removed all the pilots from the P-39s?

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## SaparotRob (Aug 15, 2021)

fubar57 said:


> What if you just removed all the pilots from the P-39s?


I never would have thought of that.


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## Snautzer01 (Aug 15, 2021)

fubar57 said:


> What if you just removed all the pilots from the P-39s?


I think you have cracked it.

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## special ed (Aug 15, 2021)

I remember Shomo and his wingman came across a flight, of I think Tonys, as a cerimony escort. It has been about 40 years since I read about it and I couldn't begin to find which book and verify my memory, but what stands out is his wingman landed first and was berated about his leader making repeated victory rolls.. He told those watching what happened and of his own victories and when asked why he had not made victory rolls of his own, he said that he had just checked out in the Mustang and was not sure how.

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## glennasher (Aug 15, 2021)

I always wondered about Shomo's career. Retired a light colonel after 26 years and a MOH? He must have had a pretty lackluster or troubled career after his eventful flight in the Philippines that day. Something to think about, anyway.

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## GrauGeist (Aug 15, 2021)

Interesting bit about Maj. Shomo, he started flying for the 5th AF in 1944, flying tactical recon missions (typically a P-39Q) but on 2 September 44, led a four ship armed recon mission in a P-40, the other three being P-39s. They hit bad weather and turned back and all three P-39s were lost (all MIA), he being the only one to return.
In October '44, he transitioned to the F-6D and on 10 January 45, he claimed his first kill.
It was 11 January 45 that was his landmark mission, he and his wingman being in F-6Ds on an armed PR mission when they bounced 11 KI-61s and one KI-44 escorting a G4M at 2,500 feet.
He scored six fighters and the Betty while his wingman scored three.

So Shomo's war total was eight enemy aircraft, none of which were in a P-39, even though he heaped high praise on it.

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## DerAdlerIstGelandet (Aug 15, 2021)

Here is what I take from this:

Joe Blow Pilot who actually flew the plane < Armchair pilot who has shown he cannot read simple charts

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## FLYBOYJ (Aug 15, 2021)

special ed said:


> I remember Shomo and his wingman came across a flight, of I think Tonys, as a cerimony escort. It has been about 40 years since I read about it and I couldn't begin to find which book and verify my memory, but what stands out is his wingman landed first and was berated about his leader making repeated victory rolls.. He told those watching what happened and of his own victories and when asked why he had not made victory rolls of his own, he said that he had just checked out in the Mustang and was not sure how.


I believe one Tojo was in the flight - maybe the instructor or senior pilot?


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## Shortround6 (Aug 15, 2021)

The weight could be a typo, steel armor weighs 40lbs per sq ft for a 1 in thickness. 
750lbs is 18.75 sq ft of 1 in armor. Or 37.5 sq ft of 1/2 in armor, adjust as you see fit but something seems off.

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## pbehn (Aug 15, 2021)

I think the whole thing is a based on a typo or a deliberate mis quote/ omission to make a better story.

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## GrauGeist (Aug 15, 2021)

75 pounds would certainly be more realistic.


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## pbehn (Aug 15, 2021)

GrauGeist said:


> 75 pounds would certainly be more realistic.


And back in the mists of time I have a sort of memory that totalled up all the weight reductions, fuel cells, guns, ammo, armour etc that were also about 750Lbs, of which some could have been belly armour. From the drawing posted, if that weighed 750LBs it must have been inch thick steel at least.

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## Thumpalumpacus (Aug 15, 2021)

I bet you could save another four or five hundred pounds by ditching the landing gear.

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## wuzak (Aug 15, 2021)

10 more pages to the magic 200 guys!

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## Thumpalumpacus (Aug 15, 2021)

wuzak said:


> 10 more pages to he magic 200 guys!



Every post in this thread reduces the P-39's gross weight by eight ounces.

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## pbehn (Aug 15, 2021)

wuzak said:


> 10 more pages to the magic 200 guys!


I think the discovery of armour plate made from lead will keep things going for a while.


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## wuzak (Aug 15, 2021)

pbehn said:


> I think the discovery of armour plate made from lead will keep things going for a while.



Is that what they made the nose armour from?


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## FLYBOYJ (Aug 15, 2021)

wuzak said:


> Is that what they made the nose armour from?


No, Kryptonite


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## GrauGeist (Aug 15, 2021)

In all seriousness, as I mentioned before, the nose armor was the heaviest single component of the armor compliment.

Bell was very serious about protecting that gearbox.

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## SaparotRob (Aug 15, 2021)

GrauGeist said:


> In all seriousness, as I mentioned before, the nose armor was the heaviest single component of the armor compliment.
> 
> Bell was very serious about protecting that gearbox.


I know but it's still funny, seriously.

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## FLYBOYJ (Aug 15, 2021)

GrauGeist said:


> In all seriousness, as I mentioned before, the nose armor was the heaviest single component of the armor compliment.
> 
> Bell was very serious about protecting that gearbox.


Reading your post a light bulb came on in my head - Working around P-3s and C-130s, the propeller gear box (Reduction gear box) was not an integral part of the engine assembly (obviously in a turboshaft engine assembly) and had a driveshaft assembly about 3 or 4 feet long. We had pretty tight maintenance requirements on the "RGBs", always watching for oil consumption and leaks. We also ran 5606 hydraulic fluid in them. Some of our aircrews who saw combat talked about small arms fire and I know there was always a worry about a golden BB knocking out the RGB, at least from the Flight Engineers who were Aviation Machinist Mates (ADs)

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## GrauGeist (Aug 16, 2021)

FLYBOYJ said:


> Reading your post a light bulb came on in my head - Working around P-3s and C-130s, the propeller gear box (Reduction gear box) was not an integral part of the engine assembly (obviously in a turboshaft engine assembly) and had a driveshaft assembly about 3 or 4 feet long. We had pretty tight maintenance requirements on the "RGBs", always watching for oil consumption and leaks. We also ran 5606 hydraulic fluid in them. Some of our aircrews who saw combat talked about small arms fire and I know there was always a worry about a golden BB knocking out the RGB, at least from the Flight Engineers who were Aviation Machinist Mates (ADs)


I used to be active in drag racing and one of the most catastrophic (and feared) failures was a driveshaft.
Especially when a "pumpkin" (differential) failed, the driveshaft, now no longer under load would break away.
There is a safety loop meant to constrain the shaft in event of a failure, but more times than not, the dynamics of the shaft would tear that loose and destroy the car.

It's a terrifying sight and sound and I can safely say that a gearbox/shaft failure in an aircraft would have immediate and unforgiving circumstances.

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## ThomasP (Aug 16, 2021)

A bit of interesting info.

The Soviets refused at least 2 shipments of P-39s due to excessive vibration in the extension shaft. The article did not say how many airframes were involved.

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## Ascent (Aug 16, 2021)

GrauGeist said:


> I used to be active in drag racing and one of the most catastrophic (and feared) failures was a driveshaft.
> Especially when a "pumpkin" (differential) failed, the driveshaft, now no longer under load would break away.
> There is a safety loop meant to constrain the shaft in event of a failure, but more times than not, the dynamics of the shaft would tear that loose and destroy the car.
> 
> It's a terrifying sight and sound and I can safely say that a gearbox/shaft failure in an aircraft would have immediate and unforgiving circumstances.


I've seen a propshaft give way on an engine test Dyno once, made a very big bang and one hell of a mess of the test cell, even with a protective metal shield around it. I really wouldn't want to be in an aircraft when that happened, especially if I was sitting astride it.

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## Peter Gunn (Aug 16, 2021)

I remember reading about Maj. Shomo's 6 kill mission as a kid, I think in William Hess' "Fighting Mustang: The Chronicles of the P-51" but who was on the bomber that warranted such a large escort?


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## FLYBOYJ (Aug 16, 2021)

Peter Gunn said:


> I remember reading about Maj. Shomo's 6 kill mission as a kid, I think in William Hess' "Fighting Mustang: The Chronicles of the P-51" but who was on the bomber that warranted such a large escort?


And why one Tojo in a flight of Tonys?

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## GrauGeist (Aug 16, 2021)

FLYBOYJ said:


> And why one Tojo in a flight of Tonys?


To add to the mystery, they were escorting a Navy type.
Had to have been some brass aboard.


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## GregP (Aug 16, 2021)

This subject might be worth a new thread. The IJN and IJA hated each other. 

So, if we had IJA airplanes escorting and IJN airplane, that would be something almost unheard of, at least to my reading over 50+ years.

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## Stig1207 (Aug 16, 2021)

Late war Betty shootdown

Last post specifically adresses IJA / IJN cooperation.


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## Peter Gunn (Aug 16, 2021)

But still no data on who/why that group was flying over the Philippines?


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## GrauGeist (Aug 16, 2021)

There was periods of co-operation between the IJN and IJA, like in the Solomons.
But the Army only came to the aid of the Navy after months of deliberation and even then, it was in their terms.

The IJN exclusively escorted their officers and such, when they were in transit between areas/bases - why such a heavy IJA escort for a lone G4M must have been quite an unusual situation.

If we recall, Yamamoto and his enterauge were in two G4Ms escorted by only six A6Ms and Yamamoto was fairly important...

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## fubar57 (Aug 16, 2021)

Maybe they were moving Amelia Earhart to a new location

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## GregP (Aug 16, 2021)

Maybe the IJA fighters shot down the IJN aircraft being escorted? Now that would an interesting thing to uncover if it happened, and would support that politics was alive and well in wartime Japan.

But I'm not suggesting it happened that way, just speculating. So please don't say a claim for this this originated with me.

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## SaparotRob (Aug 16, 2021)

GregP said:


> Maybe the IJA fighters shot down the IJN aircraft being escorted? Now that would an interesting thing to uncover if it happened, and would support that politics was alive and well in wartime Japan.
> 
> But I'm not suggesting it happened that way, just speculating. So please don't say a claim for this this originated with me.


Why not? Someone should fill in for Caidin.

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## glennasher (Aug 16, 2021)

I think there is documentation that Tojo had tried to have Yamamoto assassinated prior to Pearl Harbor, which is why Yamamoto spent so much time aboard his flagship. It's kinda hard to believe that things could have been that bad between the IJA and IJN, but I've read about it in two different places. so it might be true. Maybe.

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## GregP (Aug 16, 2021)

Interservice rivalry is alive and well today. it was alive and well in WWII and will be alive and well as long as there are budget fights to be found or until the two service have the same colors and insignias.


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## gumbyk (Aug 16, 2021)

GregP said:


> Maybe the IJA fighters shot down the IJN aircraft being escorted? Now that would an interesting thing to uncover if it happened, and would support that politics was alive and well in wartime Japan.
> 
> But I'm not suggesting it happened that way, just speculating. So please don't say a claim for this this originated with me.


Well, I've just read it on the internet, so it must be true!

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## pbehn (Aug 16, 2021)

gumbyk said:


> Well, I've just read it on the internet, so it must be true!


Ive just done a google search and can confirm it is a fact. (internet fact)

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## GrauGeist (Aug 16, 2021)

It doesn't seem there were any high ranking officers (Army or Navy) lost on 11 January 1945.
I'm wondering if the "G4M" may have been a mis-identified KI-49, perhaps?

Bombers were often used to guide a flight between bases where long distances were involved, this may have been such an occasion.

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## 33k in the air (Aug 16, 2021)

gumbyk said:


> Well, I've just read it on the internet, so it must be true!



"What I want to know is, out of all the stories you told me, which ones were true and which ones weren't?"
"My dear doctor, they're all true."
"Even the lies?"
"Especially the lies."

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## GregP (Aug 16, 2021)

I thought I was mistaken once, but I was wrong. Sort of like, "I bought some dehydrated water, but I didn't know what to add."


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## GrauGeist (Aug 16, 2021)

GregP said:


> I thought I was mistaken once, but I was wrong. Sort of like, "I bought some dehydrated water, but I didn't know what to add."


Did you try adding liquid oxygen?


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## swampyankee (Aug 16, 2021)

glennasher said:


> I think there is documentation that Tojo had tried to have Yamamoto assassinated prior to Pearl Harbor, which is why Yamamoto spent so much time aboard his flagship. It's kinda hard to believe that things could have been that bad between the IJA and IJN, but I've read about it in two different places. so it might be true. Maybe.


It wasn't so much inter-service rivalry as that Yamamoto wasn't sufficiently willing to go to war with the US or UK. While the inter-service rivalry between the IJA and IJN was severe to the point of pathology, it wasn't why officers and politicians were murdered.

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## SaparotRob (Aug 16, 2021)

GregP said:


> I thought I was mistaken once, but I was wrong. Sort of like, "I bought some dehydrated water, but I didn't know what to add."


Hey, do you remember the recipe for ice? I forgot it.


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## GregP (Aug 16, 2021)

It has something to do with hot water soup, things are getting hazy.

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## GrauGeist (Aug 16, 2021)

Just don't try and make oatmeal with the coffeemaker.
It will not end well...

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## GregP (Aug 17, 2021)

Sounds like a good cookie recipe ... coffee-oatmeal-chocolate chip. Mmmmm ....

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## 33k in the air (Aug 17, 2021)

SaparotRob said:


> Hey, do you remember the recipe for ice? I forgot it.



It's pretty simple, really:

Take two hydrogens, add one oxygen, chill until solid.

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## buffnut453 (Aug 17, 2021)

33k in the air said:


> It's pretty simple, really:
> 
> Take two hydrogens, add one oxygen, chill until solid.



Last time I tried to make ice, I ended up burning it I wonder if I turned the dial the wrong way?

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## pbehn (Aug 17, 2021)

buffnut453 said:


> Last time I tried to make ice, I ended up burning it I wonder if I turned the dial the wrong way?


Just follow a rocket, much safer.

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## GregP (Aug 17, 2021)

I can see the long-term effects: As the number of pages of replies gets larger, we revert.

Where it ends depends on how many P-39's we count jumping over a fence before we fall asleep.


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## SaparotRob (Aug 17, 2021)

buffnut453 said:


> Last time I tried to make ice, I ended up burning it I wonder if I turned the dial the wrong way?


You too?


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## 33k in the air (Aug 17, 2021)

buffnut453 said:


> Last time I tried to make ice, I ended up burning it I wonder if I turned the dial the wrong way?



Check the ingredients.

If you added two oxygens to one carbon and then chilled, you'll get something else entirely!

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## FLYBOYJ (Aug 18, 2021)

It's been quiet so I called in for some food.

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## BiffF15 (Aug 18, 2021)

FLYBOYJ said:


> It's been quiet so I called in for some food.
> 
> View attachment 638409



Yo quero Taco Bell…

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## GregP (Aug 21, 2021)

As FlyboyJ said, it's been quiet. So, I thought I'd give you something to talk about.






Not saying you SHOULD talk about it, but I found it and thought it might revive this short, currently-slow thread.

Somebody hit me.

Wonder if it would have enough range to get around the traffic pattern and still land safely?

Service ceiling was only 1,500 feet due to fuel limitations?

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## GrauGeist (Aug 21, 2021)

Then there was the Belyayev OI-2...

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## SaparotRob (Aug 21, 2021)

I sit in the presence of greatness.

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## fubar57 (Aug 29, 2021)

So anyway.....how about that P-39, eh?

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## FLYBOYJ (Aug 29, 2021)

fubar57 said:


> So anyway.....how about that P-39, eh?

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## Thumpalumpacus (Aug 29, 2021)

FLYBOYJ said:


> It's been quiet so I called in for some food.
> 
> View attachment 638409



I'd hit it. It can't be worse than airport food,

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## nuuumannn (Aug 29, 2021)

pbehn said:


> Ugly, stupid babies can be helped by sympathetic relocation of the compass.



Nothing is truly useless, it can always be used as a bad example...



Thumpalumpacus said:


> I think the only real goof-up was the non-laminar-flow wing on the model.



I reckon your recognition is out; it looks more like a Gulfstream...



SaparotRob said:


> Remember Northwest Airlines? I took a flight with them ONCE and found out why it was called "Northworst".



I remember taking a Northwest DC-10 from the UK to the US a while back now, it was one of the last DC-10 flights Northwest operated before it retired the type.



GregP said:


> OK. Since you want controversy, which is better looking, a P-39 or this:



Looks like a Boeing 247 designed by a committee...

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## nuuumannn (Aug 29, 2021)

buffnut453 said:


> Dunno, but here's another pic in case it's of use:



Gives the pilot something to lean on...


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## nuuumannn (Aug 29, 2021)

That's me all caught up. Keep it coming, guys...

Here's a picture of an Allison in a conserved P-40.




NZ3220 i

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## Thumpalumpacus (Aug 29, 2021)

FLYBOYJ said:


> It's been quiet so I called in for some food.
> 
> View attachment 638409



I'm on that like white on rice. Tacos and airplanes? Why isn't this line longer?

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## Andrew Arthy (Aug 29, 2021)

Found this in the memoirs of an 81st FG pilot who flew the P-39 in North-West Africa, and remembered this thread:

"*Airacobra Chant*
_
Oh, place me not in a P-39
Where the flak is thick and the M.E.'s whine
Where all you've got is a prop and a prayer,
To carry you all through flak filled air.
For the M.E.'s wait for a man in a Bell
To drive him straight to hell.
I've been across and I don't want to go back
For the Jerry has too damn much flak.
Whether your bar be silver or gold
Five sorties and you're damn sure old
For the purple heart or the silver star
I'll gladly take the U.S. Bar.
Just send me across the deep blue sea
And place me in the big B.T.
Where the blonde headed girls can swarm around me.
Or place me behind a hardwood desk
With a good sharp pen and an elbow rest
In closing words of this fruitful song
Your life in a Bell can't be too long.

Author Unknown_"

Cheers,
Andrew A.
Air War Publications - www.airwarpublications.com

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## GrauGeist (Aug 29, 2021)

nuuumannn said:


> That's me all caught up. Keep it coming, guys...
> 
> Here's a picture of an Allison in a conserved P-40.
> 
> ...


Shouldn't that have nose armor?

Asking for a friend, of course.

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## nuuumannn (Aug 29, 2021)

GrauGeist said:


> Shouldn't that have nose armor?
> 
> Asking for a friend, of course.



Shucks... You guys... ;D


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## GrauGeist (Aug 30, 2021)




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## WARSPITER (Aug 30, 2021)

Sorry about this but what exactly is a P-39 ? - I've forgotten

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## Peter Gunn (Aug 30, 2021)

WARSPITER said:


> Sorry about this but what exactly is a P-39 ? - I've forgotten


Beats me.


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## nuuumannn (Aug 30, 2021)

WARSPITER said:


> Sorry about this but what exactly is a P-39 ?



you're not gonna believe this, given the forum we're on...









Bible Gateway passage: Psalm 39 - New International Version


Psalm 39 - For the director of music. For Jeduthun. A psalm of David. I said, “I will watch my ways and keep my tongue from sin; I will put a muzzle on my mouth while in the presence of the wicked.” So I remained utterly silent, not even saying anything good. But my anguish increased; my heart...




www.biblegateway.com

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## Peter Gunn (Aug 30, 2021)

nuuumannn said:


> you're not gonna believe this, given the forum we're on...
> 
> 
> 
> ...


Which reminds me of something amusing when, about 10 years ago, on an online game, I took the name Peter_Three_Eight after of course, our beloved twin Allison powered beauty.

When Lo, I did begin to get compliments on picking such a meaningful verse for my screen name:

1 Peter 3:8
King James Version​8 ​Finally, be ye all of one mind, having compassion one of another, love as brethren, be pitiful, be courteous:

In retrospect, I fairly like it.

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## nuuumannn (Aug 30, 2021)

Peter Gunn said:


> Finally, be ye all of one mind, having compassion one of another, love as brethren, be pitiful, be courteous:



I'm not a religious man, but that's a good maxim to live by.

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## WARSPITER (Aug 30, 2021)

In other words - everyone has forgotten what a a P-39 is ?


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## fubar57 (Aug 30, 2021)



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## Clayton Magnet (Aug 30, 2021)

"Real wireless free"
So its free from being wireless?

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## WARSPITER (Aug 30, 2021)

No it's just less wireless than free - is the engine in the middle though ?

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## GregP (Aug 30, 2021)

As we have heard, all airplanes are a compromise and no single airplane is best at all missions.

The P-39 is a true compromise, not being the best at ANY mission. It seems to be mediocre at ALL missions and had a rearward CG after it attacks anything. So, once the heart-pounding combat is finished, you have the heart-pounding flight-back-home-without-tumbling to finish.

That is, of course, an exaggeration, but seems to fit the theme at this time.

Wonder how the P-39 would have faired had a 2-stage Merlin been installed? That actually might fit. It could have been a sparkling performer that couldn't win anything because it didn't have the range to get there to fight.

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## FLYBOYJ (Aug 30, 2021)

GregP said:


> Wonder how the P-39 would have faired had a 2-stage Merlin been installed? That actually might fit. It could have been a sparkling performer that couldn't win anything because it didn't have the range to get there to fight.

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## GrauGeist (Aug 30, 2021)

The P-63B was to have the Packard Merlin, but demand for the V-1650 for P-51 production killed that concept.

Even the P-63's intended Merlin prototype, XP-63A s/n 42-78015 had it's engine fitting cancelled due to a lack of an available Merlin, so it ended up with a V-1710-93 instead.


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## pbehn (Aug 30, 2021)

A mid engined plane is like a mid engined car. It solves one problem elegantly but creates a lot of other problems too.

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## GregP (Aug 30, 2021)

Here's a P-39 with the nose of a Westland Wyvern grafted on. Sort of a Wy-a-Cobra. Seems appropriate.







No real use for it, but man's reach should exceed his grasp, hopefully.

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## SaparotRob (Aug 30, 2021)

Maybe Wye E. Cobra, Super Genius?

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## glennasher (Aug 30, 2021)

GregP said:


> Here's a P-39 with the nose of a Westland Wyvern grafted on. Sort of a Wy-a-Cobra. Seems appropriate.
> 
> View attachment 639936
> 
> ...


That thing looks like a duck, a seriously malformed duck. Even Daffy would be ashamed of that thing.

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## BiffF15 (Aug 30, 2021)

It needed a contra prop for CG control.


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## GregP (Aug 30, 2021)

I'm ashamed of it, and I posted it. Has a face that would make a train want to take a dirt road on a rainy night.

But, I like it better than this one:






If that was a girl, you'd have to tie a roast beef to her face to get the dog to play with her.

Bad Greg, bad Greg. Repeat as required for suitable shame.

Maybe it would make a good control line model?

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## drgondog (Aug 30, 2021)

GregP said:


> Here's a P-39 with the nose of a Westland Wyvern grafted on. Sort of a Wy-a-Cobra. Seems appropriate.
> 
> View attachment 639936
> 
> ...


Probably need to move the wing about two feet forward - minimum


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## Ovod (Aug 30, 2021)

GregP said:


> Wonder how the P-39 would have faired had a 2-stage Merlin been installed? That actually might fit. It could have been a sparkling performer that couldn't win anything because it didn't have the range to get there to fight.



How did the range/endurance of the P-39 actually compare with the Spitfire? How did they compare in range when both were carrying a 500 lb pound bomb?


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## pbehn (Aug 30, 2021)

drgondog said:


> Probably need to move the wing about two feet forward - minimum


It should be moved to a smelter.

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## GregP (Aug 30, 2021)

For the Bell P-39Q, the range on internal fuel was 525 miles. That puts the combat range at something on the order of 262 miles or less before a turnaround, excluding any combat that required more than cruise fuel flow. A Spitfire II had a combat range of 248 miles. Combat range is a radius, so the P-39 and Spitfire II were very similarly short-legged.

For range when they were loaded, try Google or the POH for that. Neither one was exactly a long-range mount, but the Spitfire II didn't "tumble and roll and dig a big hole." The P-39 sometimes did.

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## wuzak (Aug 30, 2021)

Ovod said:


> How did the range/endurance of the P-39 actually compare with the Spitfire? How did they compare in range when both were carrying a 500 lb pound bomb?



The Spitfire did its best fighting after it ran out of fuel. It could fly for miles, climb, roll, and turn when the critical engine was dead.

I saw it in a documentary titled _Dunkirk_.

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## GregP (Aug 30, 2021)

Documentary?

And here I thought it was just historical artistic license. That's sort of like calling someone who is ugly "appearance disadvantaged" or someone who is bald "hairline impaired."

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## Peter Gunn (Aug 31, 2021)

WARSPITER said:


> In other words - everyone has forgotten what a a P-39 is ?


Like 

 nuuumannn
says, not trying to be religious but funny how things work out. Even during the most heated exchanges here on the Airacobra I hope we didn't devolve to personal attacks. So to expand on my old gaming screen name, if I had chosen Peter_Three_Nine:

1 Peter 3:9​9 ​Do not repay evil with evil or insult with insult. On the contrary, repay evil with blessing, because to this you were called so that you may inherit a blessing.

I'd like to think our buddy the Expert was not repaid with insults here.

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## WARSPITER (Aug 31, 2021)

Therefore it may be that we should bless the P-39 as many seem to think it's flight characteristics to be on the evil side of the ledger ?

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## fubar57 (Aug 31, 2021)

.....or as one member thinks

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## GrauGeist (Aug 31, 2021)

To be fair, Bell designed and built an aircraft to satisfy the USAAC's unhealthy obsession with the 37mm cannon and for a mission profile that never happened.

It would be interesting to see what Bell would have come up with had there been no cannon requirement - in other words, designed for conventional armament arrangement instead.


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## fubar57 (Aug 31, 2021)

Maybe Bell was using this as a role model; mid-engine with 37mm cannon, no nose armour included.....Vickers Type 161





PUBLIC DOMAIN​

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## Clayton Magnet (Aug 31, 2021)

GrauGeist said:


> It would be interesting to see what Bell would have come up with had there been no cannon requirement - in other words, designed for conventional armament arrangement instead.


Revisionist history here, but I suspect they could have easily stuffed 3 Oerlikon FFL cannons into the nose, if that was the intent from day 1. 
That would have been a HEALTHY armament for the day, no need for heavy wing guns. While we are at it, they could have deleted the IFF, nose armour, moved the radio, shoehorned in a 2 stage supercharger,........

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## FLYBOYJ (Aug 31, 2021)

Clayton Magnet said:


> Revisionist history here, but I suspect they could have easily stuffed 3 Oerlikon FFL cannons into the nose, if that was the intent from day 1.
> That would have been a HEALTHY armament for the day, no need for heavy wing guns. While we are at it, they could have deleted the IFF, nose armour, moved the radio, shoehorned in a 2 stage supercharger,........

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## GregP (Aug 31, 2021)

Yeah, they COULD have designed a good aircraft, but they didn't. 

They designed a mediocre one. And it was designed to mediocre specifications supporting a mission it really almost never flew in real life.

Given what they had to deal with, they didn't do a bad job. But they DID design an aircraft with very little potential for developmental weight and power gains. And we KNOW how often later models of a fighter get simultaneously lighter and more powerful, don't we? Never.

The Bf 109, Spitfire, P-51, P-40, P-38, and P-47 all got heavier and more powerful as they were developed. 

The P-39 just got heavier as it went along. Technically, it DID get a slight jump in power, but never as much as it really needed.

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## Thumpalumpacus (Aug 31, 2021)

Like so many aircraft of the era, it got outstripped by events and further developments. What we say down here: _A day late and a dollar short._

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## Peter Gunn (Sep 1, 2021)

I think that's what irks me the most about the P-39, it looks great, I like the tricycle landing gear, the mid engine, all the quirky stuff too. But the performance just isn't there, so many if's and might have been's it makes your head spin, but to me it's still a great _looking_ airplane.

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## GrauGeist (Sep 1, 2021)

.


Peter Gunn said:


> I think that's what irks me the most about the P-39, it looks great, I like the tricycle landing gear, the mid engine, all the quirky stuff too. But the performance just isn't there, so many if's and might have been's it makes your head spin, but to me it's still a great _looking_ airplane.


I don't recall who made the statement, but when the prototype was rolled out, they admired it's design and compared it's nose to that of a bullet (since no engine and associated radiators, cooling flaps and such).

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## WARSPITER (Sep 1, 2021)

Ahh... that explains it then. If the nose is a bullet you don't need to armour it then.

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## buffnut453 (Sep 1, 2021)

GregP said:


> That's sort of like calling someone who is ugly "appearance disadvantaged" or someone who is bald "hairline impaired."



Baldness is not being "hairline impaired"....it's having a French hair-do - constantly retreating.

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## fubar57 (Sep 1, 2021)

Yikes!!!

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## Peter Gunn (Sep 1, 2021)

buffnut453 said:


> Baldness is not being "hairline impaired"....it's having a French hair-do - constantly retreating.

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## Reluctant Poster (Sep 1, 2021)

WARSPITER said:


> Ahh... that explains it then. If the nose is a bullet you don't need to armour it then.


I thought the nose was bullet shaped to allow the P39 to penetrate the ground more easily.

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## WARSPITER (Sep 1, 2021)

Reluctant Poster said:


> I thought the nose was bullet shaped to allow the P39 the penetrate the ground more easily.



Thus the later models coffin lid shaped all wooden wing design known as a laminated flow (ah come on it's late here... I know..hat, coat, let the doorknob hit ya where the good Lord
split ya ... )

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## vikingBerserker (Sep 1, 2021)

My God, I'm FRENCH!!!

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## drgondog (Sep 1, 2021)

GrauGeist said:


> To be fair, Bell designed and built an aircraft to satisfy the USAAC's unhealthy obsession with the 37mm cannon and for a mission profile that never happened.
> 
> It would be interesting to see what Bell would have come up with had there been no cannon requirement - in other words, designed for conventional armament arrangement instead.


The RFP was stated for Interceptor - one S/E (Bell) and one T/E (P-38) and Turbosuperchargers Required to meet the altitude performance specs. Kelsey would later say that the XP-39 was the 'small solution'. The P-400 reflected what a customer thought of the M-4.


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## Thumpalumpacus (Sep 1, 2021)

Reluctant Poster said:


> I thought the nose was bullet shaped to allow the P39 to penetrate the ground more easily.



That is, after all, what groundhogs do. This could be natural selection at work.

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## GregP (Sep 1, 2021)

So ... it's really a Burrowing Airacobra?


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## GrauGeist (Sep 1, 2021)

GregP said:


> So ... it's really a Burrowing Airacobra?


Pretty much...


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## WARSPITER (Sep 1, 2021)

GrauGeist said:


> Pretty much...
> 
> View attachment 640128



Note also the laminated wings have burnt off.


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## buffnut453 (Sep 1, 2021)



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## Thumpalumpacus (Sep 1, 2021)

GregP said:


> So ... it's really a Burrowing Airacobra?



Burrowing's the next-best thing if you climb like a -39.

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## WARSPITER (Sep 1, 2021)

Two points in it's favour then.

1. Stealth capability - could have been used by the French underground.

2. It can't be shot down if it ain't up there - should have had a no loss by enemy action record.

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## swampyankee (Sep 2, 2021)

GregP said:


> So ... it's really a Burrowing Airacobra?


The Burrowing Airacobra's design permits strafing runs on the deepest bunkers.

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## pbehn (Sep 2, 2021)

The P-39 came after the P-40, by the time it was sorted it was a contemporary of the P-51. it had no advantage over any US or UK type in service. The prodigious range of the Mustang I with 180 gallons of fuel translated to a normal "range" of operations of about 90 miles in from the enemy coast.

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## Thumpalumpacus (Sep 3, 2021)

WARSPITER said:


> Two points in it's favour then.
> 
> 1. Stealth capability - could have been used by the French underground.
> 
> 2. It can't be shot down if it ain't up there - should have had a no loss by enemy action record.



Yabut landmines and gophers going pher it. The only plus is that if you get the spins, you're already on the ground. Drink a little water and the room will stop revolving.



swampyankee said:


> The Burrowing Airacobra's design permits strafing runs on the deepest bunkers.



That would be the Burracobra, according to the late Bill.

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## buffnut453 (Sep 3, 2021)

WARSPITER said:


> 2. It can't be shot down if it ain't up there - should have had a no loss by enemy action record.



So if a groundhog can't be shot down, can it shoot up?

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## WARSPITER (Sep 3, 2021)

buffnut453 said:


> So if a groundhog can't be shot down, can it shoot up?
> 
> View attachment 640293



That would depend on the type of drug being used wouldn't it ?


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## Thumpalumpacus (Sep 3, 2021)



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## XBe02Drvr (Sep 3, 2021)

Thumpalumpacus said:


>



Was that actually Lloyd Bridges?? Or his evil twin? Or maybe one of his brats? As you can probably tell, I don't pay much attention to the Hollywood glitterverse.

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## GrauGeist (Sep 3, 2021)

XBe02Drvr said:


> Was that actually Lloyd Bridges?? Or his evil twin? Or maybe one of his brats? As you can probably tell, I don't pay much attention to the Hollywood glitterverse.


Yep, Lloyd Bridges.

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## Thumpalumpacus (Sep 3, 2021)

XBe02Drvr said:


> Was that actually Lloyd Bridges?? Or his evil twin?

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## 33k in the air (Sep 3, 2021)

"Looks like I picked the wrong day to not fly the P-39."

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## XBe02Drvr (Sep 4, 2021)

Thumpalumpacus said:


> View attachment 640348


Schizoid, huh?

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## Reluctant Poster (Sep 4, 2021)

Thumpalumpacus said:


> on landmines and gophers going pher it. The only plus is that if you get the spins, you're already on the ground. Drink a little water and the room will stop revolving.
> 
> 
> 
> That would be the Burracobra, according to the late Bill.


I have discovered that the Russian nickname of Iron Dog was actually a mistranslation. The real name was Praire Dog

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## WARSPITER (Sep 4, 2021)

SO in Soviet terms it was a CCCP-39 ?


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## Reluctant Poster (Sep 4, 2021)

WARSPITER said:


> SO in Soviet terms it was a CCCP-39 ?


CCCP-39 was a Soviet TV channel

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## SaparotRob (Sep 4, 2021)

Reluctant Poster said:


> I have discovered that the Russian nickname of Iron Dog was actually a mistranslation. The real name was Praire Dog



I haven't seen these guys in YEARS! I used to watched it with my grandfather. Thanks for the blast from the past.

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## Thumpalumpacus (Sep 4, 2021)

XBe02Drvr said:


> Schizoid, huh?



Don't take my word for it. I once saw a similar case one Saturday morning:

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## Peter Gunn (Sep 7, 2021)

XBe02Drvr said:


> Was that actually Lloyd Bridges?? Or his evil twin? Or maybe one of his brats? As you can probably tell, I don't pay much attention to the Hollywood glitterverse.


Wait, do you mean to say you've never seen the early '80's classic "Airplane"? My God man, I feel so bad for you. This was back when they still made bona fide movies.

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## vikingBerserker (Sep 7, 2021)

One of the funniest movies ever made!

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## GrauGeist (Sep 7, 2021)

The movie had a star studded cast, incuding an appearance by Otto Pilot.

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## Shortround6 (Sep 7, 2021)

It might have been closer to true life in regards to many aspects of airline operations than most other movies. 

Much like the TV show "Barney Miller" has been, at times, one of the most true to life police shows on television. 😊

Actual airline employees can judge better than me.

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## Reluctant Poster (Sep 7, 2021)

Shortround6 said:


> It might have been closer to true life in regards to many aspects of airline operations than most other movies.
> 
> Much like the TV show "Barney Miller" has been, at times, one of the most true to life police shows on television. 😊
> 
> Actual airline employees can judge better than me.


Airplane is based virtually word for word on Zero Hour


Zero Hour in turn is based on Flight into Danger, a CBC made for TV movie staring James Doohan in the Ted Stryker Type role.
If you don’t know who James Doohan is……..

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## FLYBOYJ (Sep 7, 2021)

We just need some Cockpit Resource Management around here!


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## FLYBOYJ (Sep 7, 2021)

Reluctant Poster said:


> Airplane is based virtually word for word on Zero Hour
> 
> 
> Zero Hour in turn is based on Flight into Danger, a CBC made for TV movie staring James Doohan in the Ted Stryker Type role.
> If you don’t know who James Doohan is……..



Excellent! Ted Stryker is played by Dana Andrews. "I haven't been this sick since I watched that Ronald Reagan film."

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## Reluctant Poster (Sep 7, 2021)

FLYBOYJ said:


> Excellent! Ted Stryker is played by Dana Andrews. "I haven't been this sick since I watched that Ronald Reagan film."


Fun fact. When flight into danger was shown on the BBC it was so successful that the BBC poached the producer Sidney Newman. Sidney Newman created Police Surgeon which became The Avengers and was in large part responsible for a science fiction TV series some of you may have heard of, Dr Who.





History of Doctor Who - Wikipedia







en.wikipedia.org

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## GrauGeist (Sep 7, 2021)

Loved the Avengers.

Especially Miss Emma Peel!

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## XBe02Drvr (Sep 7, 2021)

Peter Gunn said:


> Wait, do you mean to say you've never seen the early '80's classic "Airplane"? My God man, I feel so bad for you. This was back when they still made bona fide movies.


Nope. Spoilsport that I am, I was too busy flying the line (1400 hrs a year with a 4 hour commute each way), renovating a shack into a home, and teaching my girlfriend to fly to waste time in a movie theater. The only movie I remember seeing in those days was "Always", Steven Spielberg's updated take on the old classic, "A Man Named Joe".

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## FLYBOYJ (Sep 7, 2021)

XBe02Drvr said:


> Nope. Spoilsport that I am, I was too busy flying the line (1400 hrs a year with a 4 hour commute each way), renovating a shack into a home, and teaching my girlfriend to fly to waste time in a movie theater. The only movie I remember seeing in those days was "Always", Steven Spielberg's updated take on the old classic, "A Man Named Joe".


"A Guy Named Joe"


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## XBe02Drvr (Sep 7, 2021)

FLYBOYJ said:


> "A Guy Named Joe"
> View attachment 640790


Sorry, Joe! Mea culpa. Didn't mean to mangle you!
BTW, back in the the day, did they actually fly those B26 airtankers single pilot?

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## FLYBOYJ (Sep 8, 2021)

XBe02Drvr said:


> Sorry, Joe! Mea culpa. Didn't mean to mangle you!
> BTW, back in the the day, did they actually fly those B26 airtankers single pilot?


no worries and correct!

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## Peter Gunn (Sep 8, 2021)

XBe02Drvr said:


> Nope. Spoilsport that I am, I was too busy flying the line (1400 hrs a year with a 4 hour commute each way), renovating a shack into a home, and teaching my girlfriend to fly to waste time in a movie theater. The only movie I remember seeing in those days was "Always", Steven Spielberg's updated take on the old classic, "A Man Named Joe".


"A guy named Joe" was way better than "Always". You must see "Airplane", you are missing a slice of life that no man should be without.

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## Reluctant Poster (Sep 8, 2021)

Reluctant Poster said:


> Airplane is based virtually word for word on Zero Hour
> 
> 
> Zero Hour in turn is based on Flight into Danger, a CBC made for TV movie staring James Doohan in the Ted Stryker Type role.
> If you don’t know who James Doohan is……..



One final James Doohan fact. He was playing a ships engineer loooonngg before Star Trek

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## Escuadrilla Azul (Sep 14, 2021)

Shortround6 said:


> To answer,
> 1, you are correct. there were a number of 2 speed superchargers. a gear change mechanism allowed for two optimum altitudes. Merlin X engine used the same supercharger as the III and VIII but used different gear ratios and the pilot had a choice. Some aircraft used a variable drive but only between certain limits. No 3 speed supercharger every made it to service in any numbers.
> 2. again you are correct, except for the last part which you have a bit backwards. the first compresser is the one that could be skipped on some aircraft. On a turbocharged aircraft the air still went through the compressor before going to the engine driven supercharger, the compressor in the turbo just wasn't spinning very fast. All turbocharged aircraft used two compressors in series.
> 
> ...


Quite interesting, only one doubt I have. How do the water injection works? If you mix gasoline with water, don't it make harder to ignite the gasoline? How do you keep the water from freezing at high altitude? With a heater in the water tank? With exhaust gases?


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## Snautzer01 (Sep 14, 2021)

Escuadrilla Azul said:


> Quite interesting, only one doubt I have. How do the water injection works? If you mix gasoline with water, don't it make harder to ignite the gasoline? How do you keep the water from freezing at high altitude? With a heater in the water tank? With exhaust gases?








Water injection (engine) - Wikipedia







en.m.wikipedia.org

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## swampyankee (Sep 14, 2021)

Escuadrilla Azul said:


> Quite interesting, only one doubt I have. How do the water injection works? If you mix gasoline with water, don't it make harder to ignite the gasoline? How do you keep the water from freezing at high altitude? With a heater in the water tank? With exhaust gases?


The water is mixed with alcohol, usually methanol, to prevent freezing.

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## pbehn (Sep 14, 2021)

Escuadrilla Azul said:


> Quite interesting, only one doubt I have. How do the water injection works? If you mix gasoline with water, don't it make harder to ignite the gasoline? How do you keep the water from freezing at high altitude? With a heater in the water tank? With exhaust gases?


In the storage tank it is water, by the time it is introduced to the inlet manifold it is H2O as vapour/steam, the inlet charge is both heated and compressed, the "water's" job there in part is to cool the mixture.

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## fubar57 (Sep 14, 2021)

My buddy used water injection on one of the many engines (8-9 of various sizes) he installed in his '71 Ford 4x4. He raced and beat Corvettes with it

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## XBe02Drvr (Sep 15, 2021)

swampyankee said:


> The water is mixed with alcohol, usually methanol, to prevent freezing.


Topping off the water/meth and recording the amount consumed in the day's operations was part of the nightly servicing and inspection on our Fokker 27s. Crews were tasked with recording parameters for every takeoff, including duration of water/meth injection, which along with amount consumed, was fed into a computer which attempted to monitor the health of the RR Dart engines.

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## BiffF15 (Sep 15, 2021)

The Fairchild Metroliner in USAF (RC-26) service used water as well at high gross weights and hot temps. Our performance data went to 41C IIRC. It sucked to be the only thing flying on super hot days in the Middle East. We did not track anything other than a “wet” takeoff. The tough part was how to do a single engined missed without over torquing the engine and making your problems worse. Water would be required for a heavy / hot missed approach/ go around. While on the approach your power would be up on the good engine, then if required to go around, when you wanted the power up, you would have to pull it back in order to turn on the water, then push the power back up and not over torque the engine. You could be in the weather (IMC) or close to the ground.

The lesson to be learned is to not buy an airplane based on price alone…

Cheers,
Biff

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## Reluctant Poster (Sep 15, 2021)

The Oldsmobile Jetfire was the pioneer of turbocharging in cars (along with the Corvair). It used water injection which turned out to unpopular as people tended to forget to add the fluid.


Before the bean counters took over GM was a leader in car technology.

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## SaparotRob (Sep 15, 2021)

That's not my father's Oldsmobile.

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## XBe02Drvr (Sep 15, 2021)

BiffF15 said:


> The Fairchild Metroliner in USAF (RC-26) service used water as well at high gross weights and hot temps. Our performance data went to 41C IIRC. It sucked to be the only thing flying on super hot days in the Middle East. We did not track anything other than a “wet” takeoff. The tough part was how to do a single engined missed without over torquing the engine and making your problems worse. Water would be required for a heavy / hot missed approach/ go around. While on the approach your power would be up on the good engine, then if required to go around, when you wanted the power up, you would have to pull it back in order to turn on the water, then push the power back up and not over torque the engine. You could be in the weather (IMC) or close to the ground.
> 
> The lesson to be learned is to not buy an airplane based on price alone…
> 
> ...


The only reason you guys had that plane was DOD's desire to keep Fairchild in business. On its merits, the Metroliner would have been consigned by the airline industry to the dumpster of history.
The Metro was a B26 Marauder; the BE1900/C12 a B25 Mitchell. The one tweaked to the Nth degree for the last 2% of possible performance with all of the issues that entails, while the other was a little less extreme, a little slower, more versatile, more reliable, easier to fly and maintain, and nowhere near as fragile. And no "wet" takeoffs needed, ever. In fact, not even equipped.
And you could briefly overtemp or overtorque a PT6 in an emergency without worrying about an imminent failure, or even a mandatory engine change. An HSI could be done overnight, if necessary, without dismounting the engine, and be ready for an AM departure.

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## Clayton Magnet (Sep 15, 2021)

XBe02Drvr said:


> On its merits, the Metroliner would have been consigned by the airline industry to the dumpster of history.


I always preferred working on Metro 23's over the King Air 350's, oddly enough. And rigging a TPE331 usually entailed using rig pins, as opposed to a PT6, which is more or less a performance art form. It doesn't make any sense, in retrospect, because the Beech is clearly a better aircraft, but something always bothered me about King Air/1900's. Maybe it was because something simple like removing the pilot seat damn near required the disassembly of the forward fuselage. 
I guess a King Air usually keeps its fuel on the inside, instead of the hanger floor, so there is that...

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## DerAdlerIstGelandet (Sep 15, 2021)

Clayton Magnet said:


> I always preferred working on Metro 23's over the King Air 350's, oddly enough. And rigging a TPE331 usually entailed using rig pins, as opposed to a PT6, which is more or less a performance art form. It doesn't make any sense, in retrospect, because the Beech is clearly a better aircraft, but something always bothered me about King Air/1900's. Maybe it was because something simple like removing the pilot seat damn near required the disassembly of the forward fuselage.
> I guess a King Air usually keeps its fuel on the inside, instead of the hanger floor, so there is that...



I used to work in King Air 200s, 300s, and 350s, and 1900Ds. I enjoyed working on them. Its a solid aircraft and pretty straightforward.

I know what you mean about removing a cockpit seat though.

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## pbehn (Sep 15, 2021)

Reluctant Poster said:


> The Oldsmobile Jetfire was the pioneer of turbocharging in cars (along with the Corvair). It used water injection which turned out to unpopular as people tended to forget to add the fluid.
> 
> 
> Before the bean counters took over GM was a leader in car technology.



The first American car I learned the name of.

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## XBe02Drvr (Sep 15, 2021)

Clayton Magnet said:


> something always bothered me about King Air/1900's. Maybe it was because something simple like removing the pilot seat damn near required the disassembly of the forward fuselage.





DerAdlerIstGelandet said:


> I know what you mean about removing a cockpit seat though.


I don't know what your problem was. Our guys didn't seem to have that problem. Whenever I saw them working on or under the cockpit floor, the pilot seats would be back in the cabin in disassembled form. I never worked on the 1900 myself, as I was putting in so much time flying I didn't have much time for anything else.


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## DerAdlerIstGelandet (Sep 15, 2021)

XBe02Drvr said:


> I don't know what your problem was. Our guys didn't seem to have that problem. Whenever I saw them working on or under the cockpit floor, the pilot seats would be back in the cabin in disassembled form. I never worked on the 1900 myself, as I was putting in so much time flying I didn't have much time for anything else.



I’m not sure what configuration your Kingairs had, but the ones I worked on required the galley and cockpit dividers to be removed in order to slide the cockpit seats out of the seat rails.


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## wuzak (Sep 16, 2021)

46 more posts to make it onto PAGE 200! 66 more posts to have 200 full pages!

We can do it!


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## vikingBerserker (Sep 16, 2021)

But if you slid the cockpit seats out of the seat rails, wouldn't that change the COG????


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## Peter Gunn (Sep 16, 2021)

wuzak said:


> 46 more posts to make it onto PAGE 200! 66 more posts to have 200 full pages!
> 
> We can do it!


Count me in, I'll help...


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## XBe02Drvr (Sep 16, 2021)

DerAdlerIstGelandet said:


> I’m not sure what configuration your Kingairs had, but the ones I worked on required the galley and cockpit dividers to be removed in order to slide the cockpit seats out of the seat rails.


Our 1900s had no galley, just a coat rack behind the stub bulkhead on the FO side. IIRC the armrests and seat back came off the seat, the fore and aft limiting pins came out of the seat rails (the rear outboard one was a bastard), the seat's aft rail grips slid back and lifted out of the rail, then the seat slid off the forward end of the rail and lifted out.
We had some of the first airliner configured 1900s, including the prototype, UB1, N6667L. In fact the first editions of Beech's maintenance and operations manuals depicted 67L in our company livery. She had been a sales demonstrator and was the only one we had with an autopilot, a real POS not quite ready for prime time. We had to get an STC to disable and remove the AP, which was adopted by Beech and applied to new production, as airline customers were requesting their planes not have it, and it was part of the original type certificate. She would trim up so stable the autopilot was practically redundant.

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## DerAdlerIstGelandet (Sep 16, 2021)

XBe02Drvr said:


> Our 1900s had no galley, just a coat rack behind the stub bulkhead on the FO side. IIRC the armrests and seat back came off the seat, the fore and aft limiting pins came out of the seat rails (the rear outboard one was a bastard), the seat's aft rail grips slid back and lifted out of the rail, then the seat slid off the forward end of the rail and lifted out.
> We had some of the first airliner configured 1900s, including the prototype, UB1, N6667L. In fact the first editions of Beech's maintenance and operations manuals depicted 67L in our company livery. She had been a sales demonstrator and was the only one we had with an autopilot, a real POS not quite ready for prime time. We had to get an STC to disable and remove the AP, which was adopted by Beech and applied to new production, as airline customers were requesting their planes not have it, and it was part of the original type certificate. She would trim up so stable the autopilot was practically redundant.



1900Ds have a lot more room than a King Air 350. Its much easier to remove the cockpit seats in a 1900D.


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## SaparotRob (Sep 16, 2021)

vikingBerserker said:


> But if you slid the cockpit seats out of the seat rails, wouldn't that change the COG????


Remove the nose armor.


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## wuzak (Sep 16, 2021)

SaparotRob said:


> Remove the nose armor.



Don't forget the IFF needs to be moved when you do that.

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## Just Schmidt (Sep 16, 2021)

I think we need to practice all this shifting around, it's not as easy as it seems.

Luckily I found this moving stuff around simulator:






Sokoban online game


Advanced online version of the classic Sokoban game.



www.game-sokoban.com


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## GrauGeist (Sep 16, 2021)

This seems to have been lightened considerably.
I suspect the CoG is a bit off, though...

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## wuzak (Sep 16, 2021)

I think the uneven ground makes the CoG problem look worse.

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## buffnut453 (Sep 16, 2021)

Has it just emerged from it's burrow?

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## Thumpalumpacus (Sep 16, 2021)

buffnut453 said:


> Has it just emerged from it's burrow?


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## Token (Sep 16, 2021)

Reluctant Poster said:


> Airplane is based virtually word for word on Zero Hour





Reluctant Poster said:


> Zero Hour in turn is based on Flight into Danger, a CBC made for TV movie staring James Doohan in the Ted Stryker Type role.
> If you don’t know who James Doohan is……..



And that is all related to the novel version of Zero Hour, which is Runway Zero-Eight, also by Arthur Hailey. Zero-Eight was the first of the family that I read / saw, but the family resemblance is immediate when you look at Zero Hour, Flight into Danger, Runway Zero-Eight, Terror in the Sky, Airplane, etc. And even a little bit of Airport.

So Hailey came up with the general story line and ended up doing several books/shorts based on it, and several screenplays.

Just doing my part to get to 200.

T!

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## GrauGeist (Sep 16, 2021)

wuzak said:


> I think the uneven ground makes the CoG problem look worse.


All that is needed, then, would be to move the ground down a little in back.

I'm not that great at math, but it seems that pushing the hillside down about 2 feet (.6m) would do the trick?

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## Clayton Magnet (Sep 16, 2021)

DerAdlerIstGelandet said:


> I’m not sure what configuration your Kingairs had, but the ones I worked on required the galley and cockpit dividers to be removed in order to slide the cockpit seats out of the seat rails.


Almost done. To get the cockpit dividers out, you first had to remove the forward row of seats. 
BUT, to do that, it meant sliding them as far aft as possible to get room between the seat skirt and cockpit divider, to expose the seat rail enough to pop the seat out. Every little task always seemed to be a struggle with those things. 
And then there is the damned bathtub fitting inspection and torque check, which sucked, or trying to secure the bladder tank in the nacelle. The damned clips where ALWAYS just out of reach, unless you were King Kong.
Sorry, rant more or less over.

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## DerAdlerIstGelandet (Sep 16, 2021)

Clayton Magnet said:


> Almost done. To get the cockpit dividers out, you first had to remove the forward row of seats.
> BUT, to do that, it meant sliding them as far aft as possible to get room between the seat skirt and cockpit divider, to expose the seat rail enough to pop the seat out. Every little task always seemed to be a struggle with those things.
> And then there is the damned bathtub fitting inspection and torque check, which sucked, or trying to secure the bladder tank in the nacelle. The damned clips where ALWAYS just out of reach, unless you were King Kong.
> Sorry, rant more or less over.



Trust me, I am aware. I’ve worked on probabky a hundred King Airs. Once I became a lead and inspector I left the jobs like cockpit seat removals to the newer green A&Ps. Let them pay their dues. 

Overall though, I loved working on the King Air. Its a well built aircraft.

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## Thumpalumpacus (Sep 16, 2021)

GrauGeist said:


> All that is needed, then, would be to move the ground down a little in back.
> 
> I'm not that great at math, but it seems that pushing the hillside down about 2 feet (.6m) would do the trick?



And it helps in the air too -- a -39 needs all the altitude it can get.

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## XBe02Drvr (Sep 16, 2021)

DerAdlerIstGelandet said:


> 1900Ds have a lot more room than a King Air 350. Its much easier to remove the cockpit seats in a 1900D.


Never been inside a D, but in our Bs and Cs removing cockpit seats was apparently no big deal, as the guys got it done pretty quickly. Our seats were not the palatial thrones you see in high end corporate King Airs. Think C47 passenger seats.


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## XBe02Drvr (Sep 16, 2021)

Thumpalumpacus said:


> And it helps in the air too -- a -39 needs all the altitude it can get.


Not to mention ATTITUDE.

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## DerAdlerIstGelandet (Sep 16, 2021)

XBe02Drvr said:


> Never been inside a D, but in our Bs and Cs removing cockpit seats was apparently no big deal, as the guys got it done pretty quickly. Our seats were not the palatial thrones you see in high end corporate King Airs. Think C47 passenger seats.



Yeah, in the larger 1900s it is much easier than in a King Air.

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## XBe02Drvr (Sep 16, 2021)

Clayton Magnet said:


> Almost done. To get the cockpit dividers out, you first had to remove the forward row of seats.
> BUT, to do that, it meant sliding them as far aft as possible to get room between the seat skirt and cockpit divider, to expose the seat rail enough to pop the seat out. Every little task always seemed to be a struggle with those things.


In a forward entryway 1900 it's so much easier. Nothing jammed up against the cockpit dividers and no need to remove them.


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## XBe02Drvr (Sep 16, 2021)

Thumpalumpacus said:


>



Hey, what happened to the Hammer of Justice? It's missing from the tool room! Can't find it anywhere. Open and inspect all components we've worked on this shift! Nothing goes out the door til we find it!

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## SaparotRob (Sep 16, 2021)

XBe02Drvr said:


> Hey, what happened to the Hammer of Justice? It's missing from the tool room! Can't find it anywhere. Open and inspect all components we've worked on this shift! Nothing goes out the door til we find it!


Have the new guys do it.

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## buffnut453 (Sep 16, 2021)

XBe02Drvr said:


> Hey, what happened to the Hammer of Justice? It's missing from the tool room! Can't find it anywhere. Open and inspect all components we've worked on this shift! Nothing goes out the door til we find it!



It's probably lurking with the Boots of Butt-Kicking (awaiting to see if anyone recognizes the reference!).

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## Thumpalumpacus (Sep 16, 2021)

XBe02Drvr said:


> Hey, what happened to the Hammer of Justice? It's missing from the tool room! Can't find it anywhere. Open and inspect all components we've worked on this shift! Nothing goes out the door til we find it!



It got handed off to the P-38s. Bigger biceps and all that.

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## Thumpalumpacus (Sep 16, 2021)

SaparotRob said:


> Have the new guys do it.



They can fetch up a spool of flight line and some squelch oil while they're at it.


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## XBe02Drvr (Sep 16, 2021)

Thumpalumpacus said:


> They can fetch up a spool of flight line and some squelch oil while they're at it.


And don't forget the prop wash!

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## GrauGeist (Sep 16, 2021)

Add a box of Piston Return Springs to that list

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## special ed (Sep 16, 2021)

We sent people for hangar aprons for the mechanics and red oil for the lanterns.

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## wuzak (Sep 16, 2021)

GrauGeist said:


> All that is needed, then, would be to move the ground down a little in back.
> 
> I'm not that great at math, but it seems that pushing the hillside down about 2 feet (.6m) would do the trick?



Should be within the realms of possibility.

Can't quite tell if the nose armour is still there, or if it has rusted away sufficiently to allow for improved performance.


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## wuzak (Sep 16, 2021)

GrauGeist said:


> This seems to have been lightened considerably.
> I suspect the CoG is a bit off, though...
> 
> View attachment 641740



I am not sure if the recirculated air heating system will be sufficient in this model. Might have to install a performance destroying gas heater, just like the Brits did to get out of their contract.

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## soulezoo (Sep 17, 2021)

GrauGeist said:


> This seems to have been lightened considerably.
> I suspect the CoG is a bit off, though...
> 
> View attachment 641740


That'll buff out.

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## wuzak (Sep 17, 2021)

I'm not sure that the new style nose gear will retract fully.


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## SaparotRob (Sep 17, 2021)

wuzak said:


> I'm not sure that the new style nose gear will retract fully.


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## SaparotRob (Sep 17, 2021)

Have 

 N4521U
check out the nose gear. He could fix it.

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## Greg Boeser (Sep 17, 2021)

Don't forget to oil the magnetic bearings or you are going to have issues with too much yaw.

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## bada (Sep 18, 2021)

Just pushing for the 200 Pages
russian what if based on the groundhog:
Maybe it would fly better than the original?







Edit: Image source" Unknown! n°2 " J.Miranda/P.Mercado

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## GregP (Sep 18, 2021)

where on earth did you find THAT? Just curious ...


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## GrauGeist (Sep 18, 2021)

Not sure what's going on here, but I suspect they're removing the heater and IFF...

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## Thumpalumpacus (Sep 18, 2021)

bada said:


> Just pushing for the 200 Pages
> russian what if based on the groundhog:
> Maybe it would fly better than the original?
> 
> ...



I want to see the grasshopper-legs on that thing. That's gotta be some stalky landing-gear.

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## wuzak (Sep 18, 2021)

GrauGeist said:


> Not sure what's going on here, but I suspect they're removing the heater and IFF...
> 
> View attachment 641924



Do you think they will leave the doors off as well?

Surely the weight reduction will make the P-39 a 500mph fighter?


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## nuuumannn (Sep 18, 2021)

GrauGeist said:


> Not sure what's going on here, but I suspect they're removing the heater and IFF...



They are looking for the secret to its astonishing success...

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## wuzak (Sep 18, 2021)

nuuumannn said:


> They are looking for the secret to its astonishing success...



They look lost!

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## nuuumannn (Sep 18, 2021)

wuzak said:


> They look lost!



That's why they're looking


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## nuuumannn (Sep 18, 2021)

GregP said:


> where on earth did you find THAT? Just curious ...



Secret Projects forum, the artist responsible produces some pretty good artwork and writes some interesting books.






Secret Projects Forum


Unbuilt Projects, Military and Aviation Technology




www.secretprojects.co.uk

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## GrauGeist (Sep 18, 2021)

wuzak said:


> Do you think they will leave the doors off as well?
> 
> Surely the weight reduction will make the P-39 a 500mph fighter?


It's obvious that if they left the top deck off, they could easily fit a Griffin in there with room to spare - so now we're left wondering if those treacherous British were trying to sabotage Larry Bell's world-beater.

First the heater issue and now this shocking revelation!

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## XBe02Drvr (Sep 18, 2021)

GrauGeist said:


> Not sure what's going on here, but I suspect they're removing the heater and IFF...
> 
> View attachment 641924


Searching for that missing 7/16" six point socket!

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## Greg Boeser (Sep 19, 2021)

No. It'll be the 9/16ths. It always is.

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## GrauGeist (Sep 19, 2021)

3/8 or 10mm are the worst for escaping.

It's also those bastards that are known to find the exact center beneath whatever you're working on...

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## wuzak (Sep 19, 2021)

And now we are on Page 200

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## special ed (Sep 19, 2021)

Love the new high capacity ammo boxes


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## GrauGeist (Sep 19, 2021)

Close to 4K posts, too


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## wuzak (Sep 19, 2021)

GrauGeist said:


> Close to 4K posts, too



Yes, that will be at the end of this page!


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## SaparotRob (Sep 19, 2021)

“You think so?“ he innocently asked.


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## GregP (Sep 19, 2021)

Not too sure, but we are definitely edging up on the number ...


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## SaparotRob (Sep 19, 2021)

Can you provide documentation that we’re getting closer?

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## XBe02Drvr (Sep 19, 2021)

SaparotRob said:


> Can you provide documentation that we’re getting closer?


No, it got lost under the cockpit floor in the last tumble.

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## XBe02Drvr (Sep 19, 2021)

SaparotRob said:


> Can you provide documentation that we’re getting closer?


The groundhogs ate it.

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## Thumpalumpacus (Sep 19, 2021)

This is almost like watching Bong and Lynch racing for the record.

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## SaparotRob (Sep 19, 2021)

XBe02Drvr said:


> The groundhogs ate it.


Wow! That’s what happened to my homework.
It therefore must be true.

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## GregP (Sep 19, 2021)

Well, we made 200 pages. Another six posts and it will be 4,000!

I say we all celebrate with a nice glass of Hot Air Ale!


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## GregP (Sep 19, 2021)

Cow stumbles into Pot Field!
The steaks have never been higher!

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## GregP (Sep 19, 2021)

Tried to grab the fog.

I mist.

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## GregP (Sep 19, 2021)

Dogs can't operate MRI scanners.

But catscan.

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## GregP (Sep 19, 2021)

After my friend turned vegan, it was like I never saw herbivore.

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## GregP (Sep 19, 2021)

Life without music would b flat.

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## GregP (Sep 19, 2021)

And now, don't let anyone call you average. That would be mean!

4,000!

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## nuuumannn (Sep 19, 2021)

XBe02Drvr said:


> Searching for that missing 7/16" six point socket!


I remember a guy I worked with lost his torch, one of those Led Lenser metal ones one night, and it wasn't until later that he realised that he'd left it in the rear fuselage of one of the aircraft we were working on. He decided not to tell anyone (naughty, naughty) and two weeks later when the aircraft came back to the hangar for maintenance, he went into the back and it was still sitting there, where he'd left it! Undisturbed and unnoticed! He told me after he left the company!

The company began hammering tool control after a spanner was found left in a fuel tank after a heavy maintenance visit! We on Line used to complain about the defects we'd find after heavy checks because for a period a few years ago there was always something, tape over AC ducts, rags left in engine bays, fasteners not done up properly, all sorts of issues...

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## wuzak (Sep 19, 2021)

GregP said:


> And now, don't let anyone call you average. That would be mean!
> 
> 4,000!



You positively sprinted to the line.

Like an unladen P-39!

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## gumbyk (Sep 19, 2021)

nuuumannn said:


> I remember a guy I worked with lost his torch, one of those Led Lenser metal ones one night, and it wasn't until later that he realised that he'd left it in the rear fuselage of one of the aircraft we were working on. He decided not to tell anyone (naughty, naughty) and two weeks later when the aircraft came back to the hangar for maintenance, he went into the back and it was still sitting there, where he'd left it! Undisturbed and unnoticed! He told me after he left the company!
> 
> The company began hammering tool control after a spanner was found left in a fuel tank after a heavy maintenance visit! We on Line used to complain about the defects we'd find after heavy checks because for a period a few years ago there was always something, tape over AC ducts, rags left in engine bays, fasteners not done up properly, all sorts of issues...


Our boss left a torch in the wheel well of an aircraft. about two weeks after the same thing had caused a wheels-up on a 1900...

I've left an inspection mirror on the top of an engine before.

We also had a customer come in because he had dents in the underside of his wing - but they were from the inside. Banging on the bottom of the wing revealed an 'echo' of a riveting dolly left inside... Luckily we hadn't done the repair on the wing.

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## nuuumannn (Sep 19, 2021)

gumbyk said:


> Our boss left a torch in the wheel well of an aircraft. about two weeks after the same thing had caused a wheels-up on a 1900...
> 
> I've left an inspection mirror on the top of an engine before.
> 
> We also had a customer come in because he had dents in the underside of his wing - but they were from the inside. Banging on the bottom of the wing revealed an 'echo' of a riveting dolly left inside... Luckily we hadn't done the repair on the wing.



Dollies in fuel tanks, and other nooks and crannies is soooo common! I've read of so many instances of this in accident reports and other case studies.


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## gumbyk (Sep 19, 2021)

nuuumannn said:


> Dollies in fuel tanks, and other nooks and crannies is soooo common! I've read of so many instances of this in accident reports and other case studies.


That's why part of the preflight in the Nanchang is to bang on the bottom of the rear fuselage. There isn't anything stopping dropped items from migrating their way to the rear fuse.


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## nuuumannn (Sep 19, 2021)

gumbyk said:


> That's why part of the preflight in the Nanchang is to bang on the bottom of the rear fuselage.



Brilliant! Can't really do that in an airliner...


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## gumbyk (Sep 19, 2021)

nuuumannn said:


> Brilliant! Can't really do that in an airliner...


No, but an airliner is designed to prevent most things that are dropped from falling through to control runs.


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## nuuumannn (Sep 19, 2021)

gumbyk said:


> No, but an airliner is designed to prevent most things that are dropped from falling through to control runs.



Subject to design limitations, of course. It happens all the time in airliners that things get left below floors. The Dash has neat chin panels for access under the flight deck and the space can be accessed from the inside by removing the library beneath a hatch in the flight deck floor, the ATR doesn't so with every heavy check the floors have to be lifted, which is a pain because of the way ATR has designed its floor panels.


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## XBe02Drvr (Sep 20, 2021)

gumbyk said:


> Banging on the bottom of the wing revealed an 'echo' of a riveting dolly left inside...


A "riveting dolly"? Is that Britspeak for what us ignorant colonists call a "bucking bar"?


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## Reluctant Poster (Sep 20, 2021)

XBe02Drvr said:


> A "riveting dolly"? Is that Britspeak for what us ignorant colonists call a "bucking bar"?


I thought it was a spellbinding girl.

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## Conslaw (Sep 22, 2021)

GrauGeist said:


> Not sure what's going on here, but I suspect they're removing the heater and IFF...
> 
> View attachment 641924


Maybe they are trying to turn it into an Ed "Big Daddy" Roth style hot rod.

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## GrauGeist (Sep 22, 2021)

Conslaw said:


> Maybe they are trying to turn it into an Ed "Big Daddy" Roth style hot rod.


Perhaps, but you can be sure that if Chuck Barris were in charge, the cockpit roof would be lowered about six inches and the plane would be about two inches off the ground with just a bit of whitewall showing from the wheelwell

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## Reluctant Poster (Sep 22, 2021)

GrauGeist said:


> Perhaps, but you can be sure that if Chuck Barris were in charge, the cockpit roof would be lowered about six inches and the plane would be about two inches off the ground with just a bit of whitewall showing from the wheelwell


The host of the Gong Show? I'd love to see him design a plane.








'King of Daytime TV (& supposed CIA assassin) Chuck Barris dies at 87


At one point Chuck Barris was supplying the television networks with 27 hours of entertainment a week, mostly in five-days-a-week daytime game shows.




www.nbcnews.com

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## SaparotRob (Sep 22, 2021)

George.

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## Reluctant Poster (Sep 22, 2021)

SaparotRob said:


> George.


Don’t spoil it

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## FLYBOYJ (Sep 22, 2021)



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## GrauGeist (Sep 22, 2021)

lmao @ Chuck

I know it should have been George.
I grew up around the crowd that included George.
My Dad's best friend had a '53 Merc George built.

And I post Chuck's name instead...

* edit * I almost forget, George was USN during WWII, by the way.

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## tonycat77 (Sep 23, 2021)

While looking at more info about the notorious flop that was the Lagg-3 (the early series makes the P-39D look like a P-51D), i looked up and found this, with almost no mention other than the designer Gurdkov falling in disgrace after the test pilot got killed testing this thing:
A P-39 clone !
I wonder what you guys think about the soviets wanting to clone the P-39 of all things.
Would this clone include propeller gear armor?

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## GrauGeist (Sep 23, 2021)

tonycat77 said:


> View attachment 642326
> 
> 
> While looking at more info about the notorious flop that was the Lagg-3 (the early series makes the P-39D look like a P-51D), i looked up and found this, with almost no mention other than the designer Gurdkov falling in disgrace after the test pilot got killed testing this thing:
> ...


The Soviets loved the P-39 for some reason.
This led to three proposals to copy the P-39 - Sukhoi, Gudkov and Belyayev.
Sukhoi's was a paper project and went nowhere.
Gudkov's Gu-1 project (as noted) ended in disaster (never read what happened, but what are the odds it suffered a flat spin, killing Aleksy Nikashin?) and his Gu-2 project never left the drawing board.
And Belyayev's OI-2 "twin Cobra" project never left the drawing board, either.

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## GregP (Sep 23, 2021)

Looks like it maybe had less of a CG problem. Look where the cockpit has been located. And, it has a 4-bladed prop.

Both bode well for improved CG range conducive to controlled flight after the ammunition ballast has been jettisoned.

Seems like this was the Gudkov Gu-1. They made one and it crashed on its first flight. No further details except weights. Without wing area, weight, engine power, and airfoil, it's hard to say anything about this airplane.

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## Shortround6 (Sep 23, 2021)

GregP said:


> Looks like it maybe had lees of a CG problem. Look where the cockpit has been located. And, it has a 4-bladed prop.
> 
> Both bode well for improved CG range conducive to controlled flight after the ammunition ballast has been jettisoned.
> 
> Seems like this was the Gudkov Gu-1. They made one and it crashed on its first flight. No further details except weights. Without wing area, weight, engine power, and airfoil, it's hard to say anything about this airplane.


Except it would have made a great long range escort, just look at that room behind the engine for fuel.

Just use more nose armor to get the CG to work out, and shift the radio.

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## buffnut453 (Sep 23, 2021)

Shortround6 said:


> Except it would have made a great long range escort, just look at that room behind the engine for fuel.
> 
> Just use more nose armor to get the CG to work out, and shift the radio.


That's all well and good but what about the cabin heater?

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## SaparotRob (Sep 23, 2021)

buffnut453 said:


> That's all well and good but what about the cabin heater?


Somebody trying to break a contract?

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## pbehn (Sep 23, 2021)

tonycat77 said:


> View attachment 642326
> 
> 
> While looking at more info about the notorious flop that was the Lagg-3 (the early series makes the P-39D look like a P-51D), i looked up and found this, with almost no mention other than the designer Gurdkov falling in disgrace after the test pilot got killed testing this thing:
> ...


Thats a cool looking plane with one of those cool engines that didnt require air intakes or radiators.

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## special ed (Sep 23, 2021)

Why would the Soviets waste the time and materials for clones when they could simply ask for more and more P-39s and eventually P-63s?
If it ain't broke, don't fix it.

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## gumbyk (Sep 23, 2021)

special ed said:


> Why would the Soviets waste the time and materials for clones when they could simply ask for more and more P-39s and eventually P-63s?
> If it ain't broke, don't fix it.


Because then you're indebted to a temporary ally. As it was the lend lease debts weren't settled until 1972.


> Lend Lease claims against the former Soviet Union arising from World War II were settled in a 1972 agreement between the U.S. and U.S.S.R.








Office of Development Finance, Bureau of Economic and Business Affairs: War-Related Debts of Other Countries to the U.S. Government


Fact Sheet by the Office Office of Development Finance, Bureau of Economic and Business Affairs: War-Related Debts of Other Countries to the U.S. Government



1997-2001.state.gov

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## Escuadrilla Azul (Oct 13, 2021)

This month is Halloween month, so I will take the risk of waking up a zombie.

Just finished going all the 202 pages of the groundhog thread (took some time). I manage to learn some things:

- The P-39 wasn't that bad, but the useful combat envelope was so limited that only the soviets could use it. Any other allied nation had more suited planes at hand for their needs.

- It had no room for any breakthrough improvement. The only way forward was a new plane, hence the P-63, but it was too late and too little to warrant supply disruption.

- The british were eager to pick any chance to break contracts and deals  (in this case, for an unknown reason). Been spanish, not very surprising news (with love to our british members ), but seems that the poor americans were caught off guard . Same on you naughty perfidious Albion.

- Learnt a lot about CoG, water injection, assembling and disassembling cockpit seats, forgotten tools on planes (seems like Boeing was just following industry wide practices ) and, above all, about cockpit heaters and back pain induced by front armour removal.

- But I think the most shocking is my inner conviction that the expert in the groundhog plane must be one of those more more fervently against himself. There is no other way that someone would remain so stubborn in the face of overwhelming facts, willing to endure such a beating while remaning so calm. Surely it's a troll, but one that must know you all and he is LOL every time he gets an furious answer.

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## vikingBerserker (Oct 13, 2021)




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## pbehn (Oct 13, 2021)

Escuadrilla Azul said:


> This month is Halloween month, so I will take the risk of waking up a zombie.
> Just finished going all the 202 pages of the groundhog thread (took some time). I manage to learn some things:
> - The P-39 wasn't that bad, but the useful combat envelope was so limited that only the soviets could use it. Any other allied nation had more suited planes at hand for their needs.
> - It had no room for any breakthrough improvement. The only way forward was a new plane, hence the P-63, but it was too late and too little to warrant supply disruption.
> ...


If you read the whole thread and still post this, I think it's time to just let it go.

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## GrauGeist (Oct 13, 2021)



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## vikingBerserker (Oct 13, 2021)

LMAO, that's awesome!

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## nuuumannn (Oct 13, 2021)

GrauGeist said:


>



You've won the internet today, my friend...

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## Peter Gunn (Oct 18, 2021)

Hogan's Heros, one of the best shows EVER.

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## SaparotRob (Oct 18, 2021)

My friend and I used to play Hogan's Heroes when I was in the 6th grade. His portrayal of Col. Klink was amazing.


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## Conslaw (Oct 23, 2021)

SaparotRob said:


> My friend and I used to play Hogan's Heroes when I was in the 6th grade. His portrayal of Col. Klink was amazing.


Ha ha, on my street in 6th grade we played Wild Wild West, the fights were better. I do owe Hogans Heroes my first theatrical role. In high school they needed somebody to do a german accent to play Rudolph, the head waiter of the Harmonia Gardens restaurant in "Hello Dolly". I did a slightly modified General Burkhalter impression and got the role.

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## DarrenW (Feb 20, 2022)

P-39 Expert said:


> See the chart in post #869. 38000ft ceiling and 31000ft combat ceiling. Better than P-40, P-51A, F4F, F4U, F6F, FW190, Typhoon, A6M2 and Ki-43. About the same as P-38F/G, P-47C and Me109G and better climb below 30000ft. Not as good as Spitfire IX. That about covers it for 1942/43 fighters.
> 
> P-39N had a higher rated engine than the vastly overweight P-400s rejected by the UK.


I'm trying to find this chart in post #869 but came up empty. Does anyone know where it possibly went?

And I apologize in advance to those who would like to have seen this thread die a thousand horrible deaths a thousand or so posts ago...


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## SaparotRob (Feb 20, 2022)

They're baaaaack.

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## FLYBOYJ (Feb 20, 2022)

DarrenW said:


> I'm trying to find this chart in post #869 but came up empty. Does anyone know where it possibly went?
> 
> And I apologize in advance to those who would like to have seen this thread die a thousand horrible deaths a thousand or so posts ago...


You sure it was 869?


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## DarrenW (Feb 20, 2022)

FLYBOYJ said:


> You sure it was 869?


I was going by what the 'expert' said but it's probably a typo. Couldn't find it anywhere.


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## FLYBOYJ (Feb 20, 2022)

DarrenW said:


> I was going by what the 'expert' said but it's probably a typo. Couldn't find it anywhere.


Post 869






Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)


Several years ago, my friends and I were at the range and they were plinking at a 5/16" thick steel target with their .223s set up aboit 35 yards out. It would ring like a bell with their hits. Being a smartass, I got out my 7x57 Mauser and took a shot. The target didn't move - ok, so I missed...



ww2aircraft.net


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## DarrenW (Feb 20, 2022)

Thanks for looking that up for me. Too bad the chart he speaks of isn't located in that post.


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## FLYBOYJ (Feb 20, 2022)

DarrenW said:


> Thanks for looking that up for me. Too bad the chart he speaks of isn't located in that post.


Well if you find it don't follow his lead on how to interpret it!

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## DarrenW (Feb 20, 2022)

FLYBOYJ said:


> Well if you find it don't follow his lead on how to interpret it!


Thanks for the advice. I already see huge discrepancies in his analysis concerning the service ceilings of 1943 fighters.


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## Thumpalumpacus (Feb 20, 2022)



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## GrauGeist (Feb 20, 2022)

I'm just going to share this phantom-view of a P-51 while trying not to draw attention to "lucky number thirteen".








* posted while slowly backing towards the door... *

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## BiffF15 (Feb 20, 2022)

Thumpalumpacus said:


> View attachment 658708


Fargo?

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## Thumpalumpacus (Feb 20, 2022)

BiffF15 said:


> Fargo?



Oh, I don't know, it's a .gif I found a few years ago that I thought would come in handy, and it has.

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## wuzak (Feb 21, 2022)

DarrenW said:


> I'm trying to find this chart in post #869 but came up empty. Does anyone know where it possibly went?
> 
> And I apologize in advance to those who would like to have seen this thread die a thousand horrible deaths a thousand or so posts ago...



There may have been a bit a thread merging back in the neolithic period.

The chart itself was most likely from WWII Aircraft Performance

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## SaparotRob (Feb 21, 2022)

BiffF15 said:


> Fargo?


I think so.

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## wuzak (Feb 21, 2022)

DarrenW said:


> I'm trying to find this chart in post #869 but came up empty. Does anyone know where it possibly went?
> 
> And I apologize in advance to those who would like to have seen this thread die a thousand horrible deaths a thousand or so posts ago...



Maybe these?






Groundhog Thread Part Deux - P-39 Fantasy and Fetish - The Never Ending Story (Mods take no responsibility for head against wall injuries sustained)


Picture of a dead thread creeping back to life.



ww2aircraft.net

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## Graeme (Feb 21, 2022)

BiffF15 said:


> Fargo?




Sure is Biff.
Probably just before he (Steve Buscemi) ends up up the wood chipper.
Dunno why - but I love that scene. Probably the attempt of 'hiding' blood in snow.

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## DarrenW (Feb 21, 2022)

wuzak said:


> Maybe these?
> 
> 
> 
> ...


Thanks Wuzak for the link. I hope to find it quickly as these threads were already exhausting the first time around...

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## DarrenW (Feb 22, 2022)

P-39 Expert said:


> See the chart in post #869. 38000ft ceiling and 31000ft combat ceiling. Better than P-40, P-51A, F4F, F4U, F6F, FW190, Typhoon, A6M2 and Ki-43. About the same as P-38F/G, P-47C and Me109G and better climb below 30000ft. Not as good as Spitfire IX. That about covers it for 1942/43 fighters.


Old thread but still worth correcting a few of many salient discrepancies:

I found plenty of sources which give the F6F-3 and F4U-1 similar service and combat ceilings to what's noted in the now infamous P-39N report. 

There were other gaffes as well. Such as ignoring higher performing versions of the Zero which arrived by1943 (reliable sources put the A6M5's ceiling at 38,520 feet). It's also pretty well established that P-38F/Gs, P-47Cs, and many 1942/43 vintage Bf109Gs were capable of altitudes in the region of 40,000 feet and more. 

Now I do realize that fighting normally took place at much lower altitudes but facts are facts and the reason for twisting them was to somehow support a flawed belief that the P-39N could leave 95 percent of it's competition in the dust. Utter nonsense.

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## Greg Boeser (Feb 22, 2022)

I understand it had the highest flat spin rate of all of them.

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## buffnut453 (Feb 22, 2022)

Greg Boeser said:


> I understand it had the highest flat spin rate of all of them.



That's what enabled it to burrow so effectively...that plus the nose armour.

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## GrauGeist (Feb 22, 2022)

Did anyone ever consider that the flat-spin may have been a secret weapon to shock and awe the enemy into retreat?

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## Greg Boeser (Feb 22, 2022)

It was a useful combat maneuver. If a Zero is on your tail just pull back on the stick and BINGO, now it's right in front of you - on your tail again - in front - behind. Then you just need an hour or two to climb back to combat altitude. What? I don't have an hour or two of endurance? Oh, well. He who fights and spins away...

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## GrauGeist (Feb 22, 2022)

Greg Boeser said:


> It was a useful combat maneuver. If a Zero is on your tail just pull back on the stick and BINGO, now it's right in front of you - on your tail again - in front - behind. Then you just need an hour or two to climb back to combat altitude. What? I don't have an hour or two of endurance? Oh, well. He who fights and spins away...


And all the while holding down the trigger so you're hurling rounds at all the bad guys in all directions.

Sort of like a garden sprinkler.

But with bullets.

Those clever Bell engineers are SO misunderstood...

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## Greg Boeser (Feb 22, 2022)

And with three different weapons having three completely different trajectories, you're bound to hit something.

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## SaparotRob (Feb 22, 2022)

I never thought of that. Bell WAS on to something.

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## 33k in the air (Feb 22, 2022)

Greg Boeser said:


> And with three different weapons having three completely different trajectories, you're bound to hit something.



And just think of the ease of the logistics in supplying three different types of ammunition! To say nothing of ground crews having to maintain three different weapon systems!

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## Greg Boeser (Feb 22, 2022)

Why bother? The 37mm is unreliable. It's just ballast. The synchronized fifties fire too slow. And the wing mounted .30s are too weak to do damage. best remove them and fill the gun bays with beer so you can have a cold one when you land. Or maybe not. They tend to get shaken up when you tumble.

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## wuzak (Feb 22, 2022)

GrauGeist said:


> And all the while holding down the trigger so you're hurling rounds at all the bad guys in all directions.
> 
> Sort of like a garden sprinkler.
> 
> ...



And hope your wingman is out of gun range?

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## buffnut453 (Feb 22, 2022)

wuzak said:


> And hope your wingman is out of gun range?



The groundhog was so good it didn't need no stinkin' wingman!

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## GrauGeist (Feb 22, 2022)

Yep!

Plus, I don't think they had a syncronized flat-spin manouver in advanved training.

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## BiffF15 (Feb 22, 2022)

Greg Boeser said:


> And with three different weapons having three completely different trajectories, you're bound to hit something.


The ground…

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## ThomasP (Feb 22, 2022)

In case anyone is interested, I found this in my files the other day - no idea where I found it originally. I would assume this is the ~basis for the weight of 6690 lbs used in the Wright Field tests. As in most cases with USAAF useful load charts, the radio Command Set is probably included in the Weight Empty.

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## GrauGeist (Feb 23, 2022)

Glad to see the pilot is considered a "useful load"...

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## 33k in the air (Feb 23, 2022)

Greg Boeser said:


> Why bother? The 37mm is unreliable. It's just ballast. The synchronized fifties fire too slow. And the wing mounted .30s are too weak to do damage. best remove them and fill the gun bays with beer so you can have a cold one when you land. Or maybe not. They tend to get shaken up when you tumble.



I was going to suggest a flamethrower, but upon further reflection, how about a battering ram?


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## FLYBOYJ (Feb 23, 2022)

DarrenW said:


> Now I do realize that fighting normally took place at much lower altitudes *but facts are facts and the reason for twisting them was to somehow support a flawed belief that the P-39N could leave 95 percent of it's competition in the dust. Utter nonsense.*


BINGO!!!!!

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## DarrenW (Feb 23, 2022)

GrauGeist said:


> Glad to see the pilot is considered a "useful load"...


I always thought 200 lbs was considered the 'normal' crew weight for a US single-seat fighter. Weren't P-39 pilots allowed parachutes?

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## FLYBOYJ (Feb 23, 2022)

DarrenW said:


> I always thought 200 lbs was the 'normal' crew weight for an American single-seat fighter. Weren't P-39 pilots allowed parachutes?


200 or 180 pounds depending if you were on weight watchers

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## Just Schmidt (Feb 23, 2022)

GrauGeist said:


> Glad to see the pilot is considered a "useful load"...


Indeed he is, he can lean forward or back to ajust the cog.

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## GregP (Feb 23, 2022)

wuzak said:


> And hope your wingman is out of gun range?



If he's a GOOD wingman, then he's in a spin right beside you, so you have to let go of the trigger and re-engage it once per revolution to avoid killing your wingman. The timing is sort of to the tune of Foggy Mountain Breakdown or a John Phillip Sousa march. Properly done, you sling bullets everywhere for a very short time since the round per gun weren't all that much ... 200 rpg for the two nose-mounted 50's and 300 rpg for the four wing-mounted 30's. The cannon had a massive 30 rounds. That assumes a P-39N.

Of course, you are then out of ammunition and the CG has migrated aft to the point where it is tough to recover from said spin, especially simultaneously in formation, with both of you headed in the same direction.

That was all made even MORE difficult if there happened to be four P-39s spinning in formation!

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## SaparotRob (Feb 23, 2022)

What a sight that would have been. It would have been glorious.

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## GregP (Feb 23, 2022)

But, improperly done, it was a sight to warm the Axis heart as the P-39s spun down into the ground. Hopefully, there at least a few parachutes in there somewhere.

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## buffnut453 (Feb 23, 2022)

This visual sprang into my mind:

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## SaparotRob (Feb 23, 2022)

Trippy!🥴


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## GregP (Feb 23, 2022)

buffnut453 said:


> This visual sprang into my mind:




The only problem with this video is it lasts about 50 times longer than the ammunition in a P-39. Otherwise, it's spot-on.

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## fubar57 (May 4, 2022)

​LIFE Magazine, 30 March, 1942

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## GrauGeist (May 4, 2022)

It is never a good thing to wake the dead...

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## WARSPITER (May 4, 2022)

fubar57 said:


> View attachment 666808
> ​LIFE Magazine, 30 March, 1942
> 
> View attachment 666809​


False advertising wasn't really a thing back then.

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## buffnut453 (May 4, 2022)

WARSPITER said:


> False advertising wasn't really a thing back then.



I really, REALLY hope you're being sarcastic.

If you're being serious, then my response to "False advertising wasn't really a thing back then" is....Ya think?







Vitamins in donuts? Yeah...sure it's a healthy snack.






I'm no vegetarian...but hotdogs and processed salami/baloney as a way to keep trim? Really? 






By all means, put your baby in a plastic bag...that's perfectly safe! What could possibly go wrong?






And this beaut from 1947 about DDT:

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## GrauGeist (May 4, 2022)

Hey now, I'm liking that "platter full of protein"!

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## buffnut453 (May 4, 2022)

GrauGeist said:


> Hey now, I'm liking that "platter full of protein"!



I like it too....I just have a really hard time with the "keeping you trim" part 'cos that certainly does NOT work for me!

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## GrauGeist (May 4, 2022)

Well...we have to first define the word "trim".
Are they referring to nautical trim, or aeronautical trim?
Or perhaps, their definition of "trim" means a satisfied belly after eating all sorts of meat goodness - and I'm ok with that definition!

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## Shortround6 (May 4, 2022)

buffnut453 said:


> I like it too....I just have a really hard time with the "keeping you trim" part 'cos that certainly does NOT work for me!


Well..........................................you are not supposed to eat the whole party platter yourself


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## GrauGeist (May 4, 2022)

Shortround6 said:


> Well..........................................you are not supposed to eat the whole party platter yourself


Wait - what?

You're not??

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## buffnut453 (May 4, 2022)

GrauGeist said:


> Well...we have to first define the word "trim".
> Are they referring to nautical trim, or aeronautical trim?
> Or perhaps, their definition of "trim" means a satisfied belly after eating all sorts of meat goodness - and I'm ok with that definition!



There is another meaning of "trim" but this is a family show so I'll let you look it you for yourselves!

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## Shortround6 (May 4, 2022)

Trim may mean that your waist doesn't exceed you inseam by 20% or more? 

Guilty


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## Greg Boeser (May 4, 2022)

Keto before keto was cool.

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## GregP (May 4, 2022)

Back then the correct meat for breakfast was Spam.

So, Spam and eggs were cooked while smoking Camels instead of flying them.

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## XBe02Drvr (May 4, 2022)

buffnut453 said:


> There is another meaning of "trim" but this is a family show so I'll let you look it you for yourselves!


The adjective trim, silly, not the verb!


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## BiffF15 (May 4, 2022)

At pilot training each class came up with a patch, and you wore it for the duration. A few classes ahead of mine, their class patch depicted a girl in a red dress, chair flying (pretend practice flying), and was captioned, "A girl is just a girl, but trim's your friend"...

There was a big emphasis on keeping the plane in trim...

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## GrauGeist (May 4, 2022)

buffnut453 said:


> There is another meaning of "trim" but this is a family show so I'll let you look it you for yourselves!


Yep, a popular term (which immediately came to mind) from my younger days - but it was not included

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## buffnut453 (May 4, 2022)

XBe02Drvr said:


> The adjective trim, silly, not the verb!



I was thinking of the noun.

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## special ed (May 4, 2022)

fubar57 said:


> View attachment 666808
> ​LIFE Magazine, 30 March, 1942
> 
> View attachment 666809​




Soooo.....P-39 expert was in Bell's adevertising department.

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## WARSPITER (May 4, 2022)

The sarcasm button was definitely being pushed when I posted the false advertising comment.

The P39 ad immediately made me think of another ad for a cigarette company in the 50's that claimed their brand
was good as it 'cleared the lungs' and helped to stop you getting colds.

Must search the net and see if I can get some of those vitamin donuts. Eating without the guilt is great.

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## SaparotRob (May 4, 2022)

WARSPITER said:


> The sarcasm button was definitely being pushed when I posted the false advertising comment.
> 
> The P39 ad immediately made me think of another ad for a cigarette company in the 50's that claimed their brand
> was good as it 'cleared the lungs' and helped to stop you getting colds.
> ...


There was one brand of cigarettes that said “for a treat, not a treatment “.

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## GrauGeist (May 4, 2022)

There used to be a brand of Cigarettes called "Black Death" (or maybe just "Death", can't remember which) in a black box.

No advertising funny business there.


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## Peter Gunn (May 5, 2022)

I agree with 

 WARSPITER
I need some of those vitamin donuts.

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## MIflyer (May 5, 2022)

Greg Boeser said:


> The 37mm is unreliable.


In the book "Druids' Circle" the author describes what occurred when the USAAF told then RAF that the 37MM of the P-39 could do as good a job at tank busting as did the 40MM Vickers guns of the Hurricane IID.

They took a captured German tank and set it up on a firing range. They positioned a P-39 to fire at the tank. And they found out the 37MM gun would jam every time, the shells getting caught on the way out . They called in an experienced armorer and he found that the ejection lever of the 37MM was too long. They sawed it off, and then it worked. And they proved very conclusively that the 37MM could not penetrate the armor of a German tank. The 40MM Vickers could do the job.

The 37MM of the P-39 was meant for air-to-air engagements, not knocking out armored vehicles. The velocity of the round was far too slow to penetrate armored vehicles. The 37MM gun used by the JU-87G was originally a Flak gun and was designed for a much higher muzzle velocity. The claim that he Soviets used the P-39 for tank busting is just as much nonses as the assertion that they deleted the turbo from the P-39 because they chose to focus on ground attack.

Aside from that, you have to wonder what was going on if they were shipping airplanes with a gun that would jam after only 1 round.

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## Just Schmidt (May 5, 2022)

MIflyer said:


> They called in an experienced armorer and he found that the ejection lever of the 37MM was too long. They sawed it off, and then it worked.


You have the temerity to claim that something on the P-39 actually could be made to work?

Duck!


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## buffnut453 (May 5, 2022)

WARSPITER said:


> The sarcasm button was definitely being pushed when I posted the false advertising comment.



Very glad to hear that. I thought you were....but it's hard to tell sometimes (hence the way I worded my response).


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## WARSPITER (May 5, 2022)

buffnut453 said:


> Very glad to hear that. I thought you were....but it's hard to tell sometimes (hence the way I worded my response).


I'm glad you responded otherwise I may never have known about those wonderful donuts.


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## XBe02Drvr (May 5, 2022)

MIflyer said:


> Aside from that, you have to wonder what was going on if they were shipping airplanes with a gun that would jam after only 1 round.


"Hand me that hacksaw, Comrade!"

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## Thumpalumpacus (May 5, 2022)

This is the thread that would not die.

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## MiTasol (May 5, 2022)

buffnut453 said:


> Very glad to hear that. I thought you were....but it's hard to tell sometimes (hence the way I worded my response).



Maybe the mods should add a sarcasm imogi

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## gumbyk (May 5, 2022)

Peter Gunn said:


> I agree with
> 
> WARSPITER
> I need some of those vitamin donuts.


They're still fortified with vitamins, via the flour...
https://www.bioanalyt.com/flour-fortification-icheck-iron-fluoro/ 

So, EAT UP!!!!!

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## Greg Boeser (May 5, 2022)

Even better if you dunk them in Ovaltine.

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## WARSPITER (May 5, 2022)

gumbyk said:


> They're still fortified with vitamins, via the flour...
> Fortified Flour to Improve Iron and Vitamin A Status and iCheck - Bioanalyt
> 
> So, EAT UP!!!!!


Ah I see. So the hemp pasta brigade are full of something and it ain't necessarily vitamins.

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## GrauGeist (May 5, 2022)

Flour comes from a plant, sugar comes from a plant, the milk and butter comes from an animal that eats plants.

So then, how can a donut possibly be bad for you?

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## Thumpalumpacus (May 5, 2022)

GrauGeist said:


> Flour comes from a plant, sugar comes from a plant, the milk and butter comes from an animal that eats plants.
> 
> So then, how can a donut possibly be bad for you?



Cyanide is an organic compound.

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## GrauGeist (May 5, 2022)

Thumpalumpacus said:


> Cyanide is an organic compound.


So is bacon.

Both can kill you.

Choose wisely...

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## buffnut453 (May 5, 2022)

GrauGeist said:


> So is bacon.
> 
> Both can kill you.
> 
> Choose wisely...



I know which tastes better, though!

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## Thumpalumpacus (May 5, 2022)

GrauGeist said:


> So is bacon.
> 
> Both can kill you.
> 
> Choose wisely...



Yabut bacon is timeless.

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## GrauGeist (May 5, 2022)

Personally, I'm not a big fan of almonds, so bacon it is!

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## WARSPITER (May 6, 2022)

Thumpalumpacus said:


> Cyanide is an organic compound.


True but it's not as well rounded as a donut.

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## rednev (May 6, 2022)

buffnut453 said:


> I know which tastes better, though!


You have tasted cyanide ?????


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## GrauGeist (May 6, 2022)

rednev said:


> You have tasted cyanide ?????


Eat a few wild almonds - you'll know right away what cyanide tastes like.

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## WARSPITER (May 6, 2022)

Don't eat apricot kernels - they contain amygdalin which converts to cyanide in the body.

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## MiTasol (May 6, 2022)

But it is natural so it must be good for you.

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## Just Schmidt (May 6, 2022)

GrauGeist said:


> So is bacon.
> 
> Both can kill you.
> 
> Choose wisely...


I gave you bacon. Infer from that what you want.

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## Thumpalumpacus (May 6, 2022)

GrauGeist said:


> So is bacon.
> 
> Both can kill you.
> 
> Choose *Cheese* wisely...


Fix't

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## SaparotRob (May 6, 2022)

Thumpalumpacus said:


> Fix't


I wanted to give you a "creative" but..........

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## Thumpalumpacus (May 6, 2022)

SaparotRob said:


> I wanted to give you a "creative" but..........

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## Escuadrilla Azul (May 6, 2022)

Thumpalumpacus said:


> View attachment 667179


Uuuupppppssssss!

That creative slip out of my fingers!

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## Peter Gunn (May 9, 2022)

SaparotRob said:


> I wanted to give you a "creative" but..........


I think you're overly optimistic...

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## tommayer (May 9, 2022)

greybeard said:


> Hello!
> I was intrigued by reading of this interview with Golodnikov, especially by his mention about true performances of German fighters (color plus some correction of the text by me):
> 
> "*A. S. Nikolay Gerasimovich, if you look at any reference book, the superiority in speed of German aircraft [like] the Bf-109G and FW-190 is indisputable. Minimum 20-25 kilometers at low altitudes and up to 80-100 kilometers at high altitudes. And you say ours did not lag behind?*
> ...


Suggested reading on 39 I have NOT found in skimming this thread. 1) Nanette, Edwards Park. He flew 39s over New Guinea, went on to a long and distinguished career, part of it with the Smithsonian. Wrote very well. His book is full instances where the 39s were unable to engage because of poor climb performance, lethargic speeds at altitude, or insufficient fuel to stay and fight. However, he loved the airplane. 2) Flying American Combat Aircraft of WWII, Robin Higham. This very informative book has two sections on 39, one from a guy who flew it off Guadalcanal, the second in the Med. Both noted the performance problems. The Pacific guy did not use the cannon in air to air. The Med guy did. The Med pilot loved the airplane, and tells of an instance you serious investigators may say never happened in which 39s shot down 6-7 MEs w/o loss over Italy. Med pilot later flew P-63 in mock attacks on B-29s, considered the 63 the best of all recip fighters, much better than 51s in everything except range/endurance. All this combing of official records and quoting generals and aces is very well, but I think first hand accounts by squadron pilots are more interesting. They tell you what it was like in the real world. In this vein, I had a friend who flew 39s and then 38s talk to a college class I was teaching. During Q & A a bright young student who'd been doing extra reading asked my friend if he had not been delighted to get 38s. Answer, "Jesus no. I hated the 38. We all had the runs all the time. Six-seven hour missions in 38s, lot of cockpits smelled like untended outhouses. The 39, you were rarely up for more than an hour and half, so your sphincter had a fighting chance."

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## Escuadrilla Azul (May 9, 2022)

tommayer said:


> Suggested reading on 39 I have NOT found in skimming this thread. 1) Nanette, Edwards Park. He flew 39s over New Guinea, went on to a long and distinguished career, part of it with the Smithsonian. Wrote very well. His book is full instances where the 39s were unable to engage because of poor climb performance, lethargic speeds at altitude, or insufficient fuel to stay and fight. However, he loved the airplane. 2) Flying American Combat Aircraft of WWII, Robin Higham. This very informative book has two sections on 39, one from a guy who flew it off Guadalcanal, the second in the Med. Both noted the performance problems. The Pacific guy did not use the cannon in air to air. The Med guy did. The Med pilot loved the airplane, and tells of an instance you serious investigators may say never happened in which 39s shot down 6-7 MEs w/o loss over Italy. Med pilot later flew P-63 in mock attacks on B-29s, considered the 63 the best of all recip fighters, much better than 51s in everything except range/endurance. All this combing of official records and quoting generals and aces is very well, but I think first hand accounts by squadron pilots are more interesting. They tell you what it was like in the real world. In this vein, I had a friend who flew 39s and then 38s talk to a college class I was teaching. During Q & A a bright young student who'd been doing extra reading asked my friend if he had not been delighted to get 38s. Answer, "Jesus no. I hated the 38. We all had the runs all the time. Six-seven hour missions in 38s, lot of cockpits smelled like untended outhouses. The 39, you were rarely up for more than an hour and half, so your sphincter had a fighting chance."


Well, one thing is to fly in a plane and quite another to fight in it.

I think that Chuck Yeager said that he like to fly the 39, but I doubt he ever considered it worth to go to war with It.

*"The Med pilot loved the airplane, and tells of an instance you serious investigators may say never happened in which 39s shot down 6-7 MEs w/o loss over Italy."*

If you rember the date (aprox) it should be more or less easy to search for that combat in MAW or any other resource and clarify. Bear in mind that one thing are claims, another one confirmed kills and yet another one true kills (or at least, verificable kills)


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## fubar57 (May 9, 2022)

".....first hand accounts by squadron pilots are more interesting...."

From MAW, Vol.3...

Jerry Collingworth (a 1/Lt in the 307th Squadron, 31st Fighter Group February - May 1943)

".....The P-39 was a miserable fighter for Tunisia. We used to have to escort them because the Bf and FW outperformed them in every conceivable way, dive, climb, manoeuvre speed - you name it....."

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## GTX (May 9, 2022)



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## drgondog (May 10, 2022)

tommayer said:


> Suggested reading on 39 I have NOT found in skimming this thread. 1) Nanette, Edwards Park. He flew 39s over New Guinea, went on to a long and distinguished career, part of it with the Smithsonian. Wrote very well. His book is full instances where the 39s were unable to engage because of poor climb performance, lethargic speeds at altitude, or insufficient fuel to stay and fight. However, he loved the airplane. 2) Flying American Combat Aircraft of WWII, Robin Higham. This very informative book has two sections on 39, one from a guy who flew it off Guadalcanal, the second in the Med. Both noted the performance problems. The Pacific guy did not use the cannon in air to air. The Med guy did. The Med pilot loved the airplane, and tells of an instance you serious investigators may say never happened in which 39s shot down 6-7 MEs w/o loss over Italy. Med pilot later flew P-63 in mock attacks on B-29s, considered the 63 the best of all recip fighters, much better than 51s in everything except range/endurance. All this combing of official records and quoting generals and aces is very well, but I think first hand accounts by squadron pilots are more interesting. They tell you what it was like in the real world. In this vein, I had a friend who flew 39s and then 38s talk to a college class I was teaching. During Q & A a bright young student who'd been doing extra reading asked my friend if he had not been delighted to get 38s. Answer, "Jesus no. I hated the 38. We all had the runs all the time. Six-seven hour missions in 38s, lot of cockpits smelled like untended outhouses. The 39, you were rarely up for more than an hour and half, so your sphincter had a fighting chance."


Interesting - did You get dates and unit of the alleged 6 to zero encounter over Italy? Did You research? 

As to 'better than P-51s in everything but range and endurance', what evidence did he present - or that you personally researched to verify?

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## drgondog (May 10, 2022)

tommayer said:


> The Med pilot loved the airplane, and tells of an instance you serious investigators may say never happened in which 39s shot down 6-7 MEs w/o loss over Italy. Med pilot later flew P-63 in mock attacks on B-29s, considered the 63 the best of all recip fighters, much better than 51s in everything except range/endurance. All this combing of official records and quoting generals and aces is very well, but I think first hand accounts by squadron pilots are more interesting. They tell you what it was like in the real world. In this vein, I had a friend who flew 39s and then 38s talk to a college class I was teaching. During Q & A a bright young student who'd been doing extra reading asked my friend if he had not been delighted to get 38s. Answer, "Jesus no. I hated the 38. We all had the runs all the time. Six-seven hour missions in 38s, lot of cockpits smelled like untended outhouses. The 39, you were rarely up for more than an hour and half, so your sphincter had a fighting chance."


The Med pilot 'misremembered' the 6-7 ME's over Italy. The ONLY example of more than 2 of Any Type Axix fighter in MTO by P-39 in one day was 93FS/81st FG with 3 on 6/11/43. At that time the 81st FG based at Monastir Tunisia..Far WEST Tunisia - well over 200 miles to make contact of the 'toe' of Italy. It didn't happen.

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## Greg Boeser (May 10, 2022)

You callin' me a liar?!!
[Reaches for gun]

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## GrauGeist (May 10, 2022)

Greg Boeser said:


> You callin' me a liar?!!
> [Reaches for gun]

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## Snautzer01 (May 10, 2022)

tommayer said:


> Suggested reading on 39 I have NOT found in skimming this thread. 1) Nanette, Edwards Park. He flew 39s over New Guinea, went on to a long and distinguished career, part of it with the Smithsonian. Wrote very well. His book is full instances where the 39s were unable to engage because of poor climb performance, lethargic speeds at altitude, or insufficient fuel to stay and fight. However, he loved the airplane. 2) Flying American Combat Aircraft of WWII, Robin Higham. This very informative book has two sections on 39, one from a guy who flew it off Guadalcanal, the second in the Med. Both noted the performance problems. The Pacific guy did not use the cannon in air to air. The Med guy did. The Med pilot loved the airplane, and tells of an instance you serious investigators may say never happened in which 39s shot down 6-7 MEs w/o loss over Italy. Med pilot later flew P-63 in mock attacks on B-29s, considered the 63 the best of all recip fighters, much better than 51s in everything except range/endurance. All this combing of official records and quoting generals and aces is very well, but I think first hand accounts by squadron pilots are more interesting. They tell you what it was like in the real world. In this vein, I had a friend who flew 39s and then 38s talk to a college class I was teaching. During Q & A a bright young student who'd been doing extra reading asked my friend if he had not been delighted to get 38s. Answer, "Jesus no. I hated the 38. We all had the runs all the time. Six-seven hour missions in 38s, lot of cockpits smelled like untended outhouses. The 39, you were rarely up for more than an hour and half, so your sphincter had a fighting chance."

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## drgondog (May 10, 2022)

tommayer said:


> Med pilot later flew P-63 in mock attacks on B-29s, considered the 63 the best of all recip fighters, much better than 51s in everything except range/endurance. All this combing of official records and quoting generals and aces is very well, but I think first hand accounts by squadron pilots are more interesting. They tell you what it was like in the real world. In this vein,


Ah yes, 'real pilots'. Perhaps you might pick up Report of the Joint Fighter Conference, Patuxent River Oct 1944. Let your fingers and attention skip to the pages comprising the Questionnaires of the 80+ Army, Navy, RAF and Manufacturer Test pilots that few all the primary fighters - even the XF8F. 

If you look at the 32 individual categories ranging from best controls, cockpit, elevator authority, flight characteristics, dive stability, figter bomber, strafer, Best ailerons at 100mph and 350mph, Best Overall above 25K, Best overall below 25K you will only occasionally note P-63 above 2%. Notably Worst Cockpit at 4% and Nicest Arrangement of cockpit Controls (12%). Everything else at or below 2%.

OTOH, P-51D in top four ranging from Best Overall Below 25K (#1), Best Overall above 25K (#2), Best Strafer (#4), Best Visibility (#1), Nicest Arrangement of Engine Controls (#1), Best Cockpit (#2), Nicest Harmonization of flight controls (#2), Best Ailerons at 350mph (#1), and so on.

The P-63 was not ranked Best with more than 1% for any combat capability other than Dive Stability in which it was just behind the P-51D and Nicest Overall Stability (3% to P-51D 6%).

The P-63 wasn't even ranked at or above 1% for Best Fighter above or Below 25K, Best Ailerons at 350mph or 100mph, Best for Overload Take Off from small space, Best Fighter Bomber, Best Strafer (2%). 

In other words, the P-63 was not very impressive to a whole lotta good pilots sent to the Conference to compare different fighters and share ideas. In all fairness the P-38J barely ranked above the P-63 and it was far down the list when compared against P-51, P-38, P-47, F4U, F6F, Even the Mosquito and P-61 outranked the P-63 for best Ailerons above 350mph and at 100mph and best Strafer and Best Fighter Bomber.

In all fairness, however, it may have been the best Gunnery Target.

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## Snautzer01 (May 10, 2022)

It was the best pinball.

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## buffnut453 (May 10, 2022)

Snautzer01 said:


> It was the best pinball.



Was it a Pinball Wizard?




Yep...wearing my coat already!

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## WARSPITER (May 10, 2022)

drgondog said:


> In all fairness, however, it may have been the best Gunnery Target.


Sentence of the week so far.

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## soulezoo (May 10, 2022)

If I get a chance to run into Bud Anderson again, I'll have to ask his opinion on the -39. He got his fighter pilot training in it IIRC and assigned to a -39 sq. on the West Coast briefly. 

I have not seen him around town for awhile now. Used to run into him at the local airport once in a great while.

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## GrauGeist (May 10, 2022)

I recall some time back, that I offered my Uncle's opinion of the P-39 (which he flew) and it was discounted by a certain die-hard P-39 fan, as "third person hearsay" versus cherry-picked pilot quotes from books used to prop up their defence of the Bell product.

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## pbehn (May 10, 2022)

greybeard said:


> Hello!
> I was intrigued by reading of this interview with Golodnikov, especially by his mention about true performances of German fighters (color plus some correction of the text by me):
> 
> "*A. S. Nikolay Gerasimovich, if you look at any reference book, the superiority in speed of German aircraft [like] the Bf-109G and FW-190 is indisputable. Minimum 20-25 kilometers at low altitudes and up to 80-100 kilometers at high altitudes. And you say ours did not lag behind?*
> ...


Calum another poster here (forum name Snowygrouch) posted a lot of info about German aircraft performance. As the war went on the build quality of airframes and engines went down so much that the actual performance was nowhere near what they should have been

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## MIflyer (May 10, 2022)

I was surprised that one P-39 pilot said the P-39Q with the external .50 cal gun pods was a worse performer than the earlier models (see an article I posted from the USAF Museum Newsletter). The Q model shook more at higher speeds. While I have seen some evidence of Soviet pilots removing the external .50 cal, I have to wonder why that installation was allowed and we did not see more efforts to delete the guns in the field. I can only imagine that they did not need the higher speeds for the missions they were flying and valued the increased firepower more.. 

Also attached is an article from Aviation History Mag with some P-39 lore.

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## SaparotRob (May 10, 2022)

I think that’s the first time I ever read “P-39“ and the words “…didn’t need higher speed for their mission.” in the same sentence.

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## Thumpalumpacus (May 10, 2022)

SaparotRob said:


> I think that’s the first time I ever read “P-39“ and the words “…didn’t need higher speed for their mission.” in the same sentence.



It wasn't a slow plane, until you hit the spin!

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## Snautzer01 (May 10, 2022)

I have it on the grapevine mods are getting ready

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## WARSPITER (May 10, 2022)

The sad end of another overheated P-39 which was shot by a Japanese sniper while drinking at a waterhole.

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## GrauGeist (May 10, 2022)

Snautzer01 said:


> I have it on the grapevine mods are getting ready
> 
> View attachment 667720


Says the guy who's banned

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## fubar57 (May 10, 2022)

RAF fin flash on the right?


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## MIflyer (May 10, 2022)

And the thing everyone agreed on was the P-39's great ground handling.

That looks like a white tailed P-40 on the other side of the ditch to the right. Here is another nice P-39 photo from that same airstrip as the skinny dipping incident.

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## GrauGeist (May 10, 2022)

fubar57 said:


> RAF fin flash on the right?


Perhaps one of the ex-RAF P-400s from Australia recently arrived?


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## Greg Boeser (May 10, 2022)

RAAF or RNZAF Kittihawk.

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## MIflyer (May 11, 2022)

Just like I said... I don't k now what they mean by "Alternate Indian Ocean Paint Scheme."

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## Peter Gunn (May 11, 2022)

GrauGeist said:


> Says the guy who's banned


I believe that's "Honourably banned" to be technical...

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## Snautzer01 (May 11, 2022)

Peter Gunn said:


> I believe that's "Honourably banned" to be technical...


And proud of it.

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## MIflyer (May 12, 2022)

And, as they used to say on "Get Smart": "And Loving It."

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## GregP (May 14, 2022)

C'mon guys, the P-39 was a pretty good airplane as long as you didn't need to fight in it. You could bolt on a beer keg, go flying and get the beer cold enough right as your fuel got to emergency state. But, if you actually had to shoot some ammunition, the beer would take you well into aft CG before you could spit, which tended to foam the beer while in the spin.

So, the real solution was to drink Saki instead of beer. Then, the Japanese pilots wouldn't dare shoot at you as you were flying about cooling it. Instead, they'd wait for you to run out of fuel and force you down on one of their airstrips., where they'd take the Saki and heat it instead before drinking it.

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## warbird51 (May 16, 2022)

A good book about flying the P-39 in combat in the SWP is ‘Cobra Combat’ by Robert Case. An enjoyable read and well written.

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## Just Schmidt (May 18, 2022)

Here's something to help us reach the page 300/#5,000 goal. 



Greg meets Groundhog...

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## SaparotRob (May 18, 2022)

Just Schmidt said:


> Here's something to help us reach the page 300/#5,000 goal.
> 
> 
> 
> Greg meets Groundhog...



A welcome break. Nice.


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## Escuadrilla Azul (May 18, 2022)

Just Schmidt said:


> Here's something to help us reach the page 300/#5,000 goal.
> 
> 
> 
> Greg meets Groundhog...



I was thinking if it was worth the risk of rising the flying dead by posting it, but you take advantage.

Typo edited

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## Peter Gunn (May 19, 2022)

I'd watch it but it's that greg dude that I consider an effing blowhard. (Not OUR greg btw).

North America's P-51? Really, you can't even get that right?

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## Clayton Magnet (May 19, 2022)

Peter Gunn said:


> North America's P-51?


Also the repeatedly mispronounced "TownSEND ring"


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## wuzak (May 20, 2022)

Just Schmidt said:


> Here's something to help us reach the page 300/#5,000 goal.



We only need to get to the end of page 250 to get 5,000 posts!

That is 21 pages and 14 posts to go!


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## GrauGeist (May 20, 2022)

The Belyayev Ol-2 - double the fun, double the spin.

What's not to like?

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## wuzak (May 20, 2022)

GrauGeist said:


> The Belyayev Ol-2 - double the fun, double the spin.
> 
> What's not to like?
> 
> View attachment 669664



Should have the left-hand boom as a pusher. That way the boom could be loaded with more 37mm M4 cannons.

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## WARSPITER (May 20, 2022)

wuzak said:


> Should have the left-hand boom as a pusher. That way the boom could be loaded with more 37mm M4 cannons.


Yes. The right can pull, the left can push, then the spin can start as you take off. Might as well get it over and done with.....

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## wuzak (May 20, 2022)

WARSPITER said:


> Yes. The right can pull, the left can push, then the spin can start as you take off. Might as well get it over and done with.....



Could speed that up by having them pull in opposite directions.

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## XBe02Drvr (May 20, 2022)

GrauGeist said:


> The Belyayev Ol-2 - double the fun, double the spin.
> 
> What's not to like?
> 
> View attachment 669664


Can you imagine landing this contraption in a gusty crosswind?

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## Ovod (May 20, 2022)

XBe02Drvr said:


> Can you imagine landing this contraption in a gusty crosswind?


What was it like landing a P-38, P-61 or an F-82 in a crosswind?

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## XBe02Drvr (May 20, 2022)

Ovod said:


> What was it like landing a P-38, P-61 or an F-82 in a crosswind?


Awkward, especially the F82 with its asymmetric cockpit and taildragger configuration.

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## fubar57 (Jun 4, 2022)

Interesting caption in LIFE magazine, 7 Sep 1942

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## special ed (Jun 5, 2022)

Obviously not written by "P-39 Expert".

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## Shortround6 (Jun 5, 2022)

Obviously it was crippled by the nose armor for the attack role

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## special ed (Jun 5, 2022)

Did it need a heater or was the heat supplied by the enemy?


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## BiffF15 (Jun 5, 2022)

special ed said:


> Did it need a heater or was the heat supplied by the enemy?


I think it was from embarrassment…

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## emu27 (Aug 29, 2022)

Have been intrigued by the P-39 tumble reputation and exactly what it was, Bob Hoover provides an answer at 18:20, a Lomcovak.

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## Thumpalumpacus (Aug 29, 2022)

Two questions:

How much ammo did he have aboard during these maneuvers?

How many Bob Hoovers did the USAAC have at the time?

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## FLYBOYJ (Aug 29, 2022)

emu27 said:


> Have been intrigued by the P-39 tumble reputation and exactly what it was, Bob Hoover provides an answer at 18:20, a Lomcovak.



Great Clip, met him a few times, loved talking to him -

A few things -

Not disputing what he said about the C/G, for the most part he is 100% correct, HOWEVER, when he experienced this we don't know WHERE within the C/G envelope his aircraft was when he did these flights. As Thumpalumpacus mentioned, no indication of ammo or ballast. Where I believe the P-39 got folks in trouble is when it was flown at the most aft of the C/G envelope, and as shown within this long and drawn out thread, we showed where the C/G went when fuel and ammo was expended.

He also doesn't mention if these maneuvers were accomplished in any type of bank angle, that would surely make conditions worse.

Great guy, excellent pilot, may he RIP!

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## Thumpalumpacus (Aug 29, 2022)

FLYBOYJ said:


> He also doesn't mention if these maneuvers were accomplished in any type of bank angle, that would surely make conditions worse.



That was one thing I noticed in his hand-representations of his maneuver, that he twisted his hands a little, but never really talked about that aspect of it -- which has to change much even in my non-flier mind.



FLYBOYJ said:


> Great guy, excellent pilot, may he RIP!

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## Peter Gunn (Aug 30, 2022)

Thumpalumpacus said:


> *SNIP*
> 
> How many Bob Hoovers did the USAAC have at the time?


"There can be ONLY ONE" --> Highlander.

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