# XP-39 and the Claims



## GregP (Apr 7, 2020)

I have seen I said in here that there is no way the XP-39 went 390 mph, but have seen no proof of same except for some various quoting of poorly-documented wind tunnel testing done on the machine either before or after the turbocharger was deleted. The posters don’t bother to say. There is, however, some considerable second-tier sources that say otherwise.
There is a digitized NACA report (Engineer in Charge: A History of Langley Aeronautical Laboratory 1917 – 1958) which states that the XP-39 DID achieve 390 mph using 1,150 hp @ 20,000 feet. But, it did so at a gross weight of 5,550 lbs at takeoff.

URL: Engineer in charge . 

Look around page 199. Langley calculated that the normal P-39 with armament would come in about a ton heavier, meaning 7,550 lbs, and the maximum speed would be expected to be around 340 mph with the same powerplant setup. They achieved a wind tunnel drag reduction in a fully-faired model of 26%. This would mean a top speed of about 429 mph at 20,000 feet with an engine of 1,350 hp. The head of the FST team said that the additional air required to cool the extra HP would likely limit the maximum speed to 410 mph. This was with a “fully-faired” model that could not be achieved in real life. The reality was bound to be something less.

Bell incorporated enough changes to drop the drag by 16% instead of the theoretical 26%. But then, the engine had the turbocharger removed and the resulting engine only produce 1,090 HP. That is 60 less hp than the engine that had driven the XP-39 to 390 mph and 260 HP less than the 1,350 HP the FST team lead had assumed when he calculated 410 mph. Additionally, the 1,090 HP was achieved at 15,000 feet rather than 20,000 feet. Accounting for the 16% drag reduction, the loss of horsepower, and the added air density at the lower latitude, you get the result that the XP-39B achieved a maximum speed of 375 mph in the first flight trials.

The end result was that Bell and Air Corps expressed satisfaction with the results and asked Bell to produce the balance of the YP-39s without turbochargers. All this was done while Ben Kelsey was in Europe working on another project.

If you go to WWIIaircraftperformance.org and look at the P-39 flight test data for a YP-39 (No. 40-30), the rate of climb started out at 3,600 fpm and was still 2,260 fpm at 15,000 feet. Moving to a P-39C (No. 40-2988), the maximum speed was 379 mph at 16,100 feet and the rate of climb started out at 3,720 fpm and was still 2,360 fpm at 16,750 feet. If we move yet again to a P-39N (No. 42-4400 test dated 17 Oct 1942), we see a maximum speed of 398.5 mph at 9,700 feet (critical altitude). The climb data for this airplane shows 3,320 fpm at sea level and 3,920 fpm at 11,000 feet. It was still climbing at 3,340 fpm at 15,000 feet, but tapered off to 2,630 fpm at 20,000 feet. 20,000 feet was achieved in 5.83 minutes. I believe the P-39N was at WEP power for the test.

The performance above for test data located at wwiiaircraftperformance.org does NOT seem to me to indicate the “dog” everyone seems to think it was. Rather it indicates that the aircraft was a decent-performing aircraft when operated below 20,000 feet. I will not get into the C.G. issues here. I think we all know the aircraft could be made to tumble if stalled when the ammunition was expended. That was proved post-war. But it doesn’t seem to me to have the bad performance often attributed to it, at least in flight test, when operated at the altitudes it was produced to address in decisions made before we entered the war. I know the climb rates at Military power will be less than rates at WEP, but WEP was used by many aircraft in the heat of combat for short durations.

I am NOT saying the P-39 was a great airplane, or even that it was a good choice for a general fighter, but I am saying the test data seems to indicate that it doesn't seem to be as bad as is commonly assumed when used within its envelope.

Please note: This is NOT intended to start a debate on the use of the P-39 in the ETO, which was a higher-altitude theater of war. Rather, it seems to show why the Soviets had such a good experience with the P-39 in their lower-altitude, ground support war.

Reactions: Like Like:
2 | Agree Agree:
1 | Winner Winner:
1 | Like List reactions


----------



## Shortround6 (Apr 7, 2020)

I am not going to argue about the P-39 after the fall of 1939. 

My objection is with the people who claim the NACA/Langley ruined the airplane and the P-39 could have been the best thing since sliced bread and cold beer combined if only they left the turbo in the plane. 

In Birch Mathews book "Cobra" some of the early flights are gone over.
James Taylor was hired as the test pilot and the first flight was on April 6th and lasted 20 minutes, only real problem was elevated oil temperatures. 
The XP-39 was flying the next day as a demonstration for General Arnold. The flight had to be cut short due to high oil temperatures. 
after 15 days of testing and evaluations the plane was airborne again on the 22nd of April. Two flights totaling 47 minutes, the landing gear was cycled on both flights. 
The next day the landing gear refused to lower under power and had to be lowered manually. The nose wheel failed on landing. At this point the XP-39 had 1 hour and 40 minutes of flight time. Oil temperatures were still a problem. 
There is no documentation that the plane ever went 390mph during this time period. There are reports that the engine was limited to either 2600rpm or 2700rpm due to vibration problems with the drive shaft. A new drive shaft was designed, tested and installed by July or August of 1939 but that is after it had been to Langley. 
Mathews claims the XP-39 weighed 6,104lbs at Wright field, not the 5,500lbs often claimed. 

Langley found the radiator and oil cooler installations to be highly problematic. 

Drag coefficient as delivered to Langley was 0.0329 almost 10% worse than a Brewster Buffalo. Yes they managed to clean the plane up considerably.

Reactions: Like Like:
2 | Like List reactions


----------



## wuzak (Apr 8, 2020)

GregP said:


> I have seen I said in here that there is no way the XP-39 went 390 mph, but have seen no proof of same except for some various quoting of poorly-documented wind tunnel testing done on the machine either before or after the turbocharger was deleted.



You're looking for proof of something that didn't happen?




GregP said:


> The posters don’t bother to say. There is, however, some considerable second-tier sources that say otherwise.
> There is a digitized NACA report (Engineer in Charge: A History of Langley Aeronautical Laboratory 1917 – 1958) which states that the XP-39 DID achieve 390 mph using 1,150 hp @ 20,000 feet. But, it did so at a gross weight of 5,550 lbs at takeoff.
> 
> URL: Engineer in charge .



Unfortunately there is no actual evidence that it did 390mph.




GregP said:


> Look around page 199. Langley calculated that the normal P-39 with armament would come in about a ton heavier, meaning 7,550 lbs, and the maximum speed would be expected to be around 340 mph with the same powerplant setup. They achieved a wind tunnel drag reduction in a fully-faired model of 26%. This would mean a top speed of about 429 mph at 20,000 feet with an engine of 1,350 hp. The head of the FST team said that the additional air required to cool the extra HP would likely limit the maximum speed to 410 mph. This was with a “fully-faired” model that could not be achieved in real life. The reality was bound to be something less.



So, the 390mph, if achieved, was a non-representative hot rod?

And if adding required equipment would make the speed 340mph, shouldn't that be considered the XP-39's true potential?

Are those 400mph estimates based on a representative weight or a stripped down, non-combat read state?

Is 13% a lot of speed to drop because of added weight?




GregP said:


> If you go to WWIIaircraftperformance.org and look at the P-39 flight test data for a YP-39 (No. 40-30), the rate of climb started out at 3,600 fpm and was still 2,260 fpm at 15,000 feet. Moving to a P-39C (No. 40-2988), the maximum speed was 379 mph at 16,100 feet and the rate of climb started out at 3,720 fpm and was still 2,360 fpm at 16,750 feet. If we move yet again to a P-39N (No. 42-4400 test dated 17 Oct 1942), we see a maximum speed of 398.5 mph at 9,700 feet (critical altitude). The climb data for this airplane shows 3,320 fpm at sea level and 3,920 fpm at 11,000 feet. It was still climbing at 3,340 fpm at 15,000 feet, but tapered off to 2,630 fpm at 20,000 feet. 20,000 feet was achieved in 5.83 minutes. I believe the P-39N was at WEP power for the test.



I believe only the first XP-39 had the original configuration. The XP-39 was later modified to remove the turbo and, possibly, apply some of the aerodynamic improvements.

YP-39s were built without turbos and included the aerodynamic improvements suggested by NACA.

Reactions: Like Like:
1 | Like List reactions


----------



## GregP (Apr 8, 2020)

Hi Wuzak,

Yes, I'm looking for proof, like anyone interested in what happened. You, me, or anyone else claiming something didn't happen is no proof one way or the other. If there was a test, it is likely recorded somewhere. So, I'm hoping the test document surfaces sometime. Otherwise, there is no point discussing the XP-39 peformance with just opinions. Everyone has one.

Works both ways, Wayne. There is no actual evidence that it DIDN'T go 390 mph either.

It was not a non-representative hot-rod. It was a prototype that I'm sure they flew when they thought it was airworthy. There are a great many WWII fighters that made first flights without armament. As for your question, you'd have to ask Langley. I wasn't there when the calculations were made. But a reprint of the book/paper in the link is available if you are interested.

Your last statement I believe I covered in the original post.

The data show a P-39N that was a whisker away from 400 mph in 1942. So, while the airframe wasn't one of the faster in the war, it was also faster than some of the mainstays such as the Bf 109E. It didn't have the altitude capability of the Bf 109E but, at least in the Med and Pacific, it didn't need that either. Apparently, more altitude capability wasn't needed in Soviet service. They just stayed down low and hit the German troops, forcing the Luftwaffe to either come down and fight or stay high and be a non-factor. I'm not touting the P-39; I never was a fan of the type. I'm just observing that the test data don't seem to show me as much of a dog as is commonly believed, unless I'm missing something.


----------



## wuzak (Apr 8, 2020)

GregP said:


> Hi Wuzak,
> 
> Yes, I'm looking for proof, like anyone interested in what happened. You, me, or anyone else claiming something didn't happen is no proof one way or the other. If there was a test, it is likely recorded somewhere. So, I'm hoping the test document surfaces sometime. Otherwise, there is no point discussing the XP-39 peformance with just opinions. Everyone has one.
> 
> Works both ways, Wayne. There is no actual evidence that it DIDN'T go 390 mph either.



If it actually went 390mph there should be some record of it, be it a pilot's report or a flight test report. 80-odd years after the XP-39 flew these documents have yet to be found.

If it didn't do 390mph there will be no documents saying that it didn't do 390mph.

The absence of the first-hand account of the 390mph test is the evidence that it didn't happen. That would obviously change if such a first-hand account was to be found.


----------



## wuzak (Apr 8, 2020)

GregP said:


> It was not a non-representative hot-rod. It was a prototype that I'm sure they flew when they thought it was airworthy. There are a great many WWII fighters that made first flights without armament. As for your question, you'd have to ask Langley. I wasn't there when the calculations were made. But a reprint of the book/paper in the link is available if you are interested.



For comparison, the Spitfire I lost about 10-15mph top speed from prototype to production machine. I believe the production machine gained the externally mounted armoured screen and the 3 blade constant speed prop, vs the 2 position prop of the prototype. So added weight and drag.


----------



## Shortround6 (Apr 8, 2020)

GregP said:


> The data show a P-39N that was a whisker away from 400 mph in 1942


 The P-39N used a different radiator duct set-up, it used a different oil cooler, it had no intercooler and it no turbo hanging out the bottom. Plus the lower canopy and few other minor tweaks? The XP-39 had a much larger drag coefficient. 
Claiming that the P-39N could do nearly 400mph with about the same amount of power as the XP-39 had so the Xp-39 should be almost as fast disregards these large differences in drag between the two airplanes. 
The claim of 390mph in the time before Langley also disregards the chronic cooling problems the XP-39 had, both engine coolant and oil coolant. 
The claim of 390mph in the time before Langley also disregards the documented problems with drive shaft that lead to a restriction on maximum RPM.
It would also make a complete lie out of the chart prepared by Langley showing the estimated speeds of the XP-39 as received, as modified by Langley keeping the turbo charger and as modified using the altitude rated non turbo Allison. 
This chart indicates a max speed of 340mph at 20,000 with the speed dropping off towards sea level till it drops to just under 280mph. 

If the XP-39 had gone anywhere near 390mph (or even 365mph) somebody could have told Langley "your wind tunnel/calculations are wrong and here is the proof". 

Langley did estimate the XP-39 could have reached about 390mph at 20,000ft *AFTER *the modifications suggested by Langley were implemented. Modified radiator duct, modified oil cooler duct, modified intercooler, lowered Canopy, etc.


----------



## tomo pauk (Apr 9, 2020)

Shortround6 said:


> ...
> This chart indicates a max speed of 340mph at 20,000 with the speed dropping off towards sea level till it drops to just under 280mph.
> 
> If the XP-39 had gone anywhere near 390mph (or even 365mph) somebody could have told Langley "your wind tunnel/calculations are wrong and here is the proof".
> ...



This is the chart:

Reactions: Informative Informative:
2 | Like List reactions


----------



## Shortround6 (Apr 9, 2020)

Thank you!

BTW here is a link to a NACA report in which they describe the drag reduction measures done on 11 airplanes including the XP-39
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092657.pdf

Reactions: Like Like:
1 | Winner Winner:
2 | Informative Informative:
1 | Like List reactions


----------



## Old Jim (Apr 9, 2020)

GregP said:


> I will not get into the C.G. issues here. I think we all know the aircraft could be made to tumble if stalled when the ammunition was expended. That was proved post-war.


Can I ask where you found this information? I have read a story by Tex Johnson that said that Bell could not get this airplane to tumble. He said the AAF sent two of their expert test pilots to Bell and they could not get it to tumble.


----------



## GregP (Apr 9, 2020)

Hi Old Jim,

Very true. The wartime "experts" never flew the plane with the ammunition completely expended.

They did the test in a wind tunnel after the war (in the 19770s) and it did, in fact, tumble.

A link: 20-Foot Spin Tunnel (645) Models and Tests N-Z - NasaCRgis


----------



## GregP (Apr 9, 2020)

Hi Wayne,

Lack of documentation is not proof it didn't happen. There are a lot of wartime documents that "disappeared" after the war somehow. I'm not making any claims about the 390 mph top speed here, but I am also unwilling to say it didn't happen just because the data have not yet surfaced. We all KNOW how fast (or slow, as you like) the production P-39's were.

You are very welcome to make assumptions on your own and it won't affect the facts. I personally believe the XP-39 did not really go 390 mph in test, but I have no proof of same. The only difference between our standpoints is I'm not SURE it didn't. In point of fact, we both actually believe it was slower.

Test calculations are not proof, either. If you believe solely in theory, a bumblebee should not be able to fly, but it does somehow, and with little seeming difficulty.

Cheers.


----------



## P-39 Expert (Apr 9, 2020)

I have no idea whether the X model actually did 390mph. I do know for sure that the XP-39 would have never made production with those unadjustable ducts for coolant, oil and intercooler. Deleting that turbocharger is the best thing that could have happened to the P-39. Had the AAF continued with an aggressive weight reduction program they would have had performance similar to the P-39N in 1941-42.


----------



## wuzak (Apr 9, 2020)

GregP said:


> Lack of documentation is not proof it didn't happen. There are a lot of wartime documents that "disappeared" after the war somehow.



Hi Greg,

While documents may have existed that showed the XP-39 doing 390mph, and those documents disappeared at some point, there was never a document that says that the XP-39 *didn't* do 390mph.

So it is very difficult to produce evidence that it didn't do 390mph. The only thing we can go on is the lack of evidence that it did do 390mph.

P-39 Expert, or anybody else, are there any record of XP-39 test flights prior to it going to NACA?


----------



## davparlr (Apr 10, 2020)

I am also in a confused state about the P-39. I just got through reading the book "The First Team and the Guadalcanal Campaign" and I had read General Kenney's report relative to the fighting on New Guinea. Both time periods were similar and there was overlapping missions. Relative to the P-39, General Kenney wanted more of them, he preferred the P-38, but they were unavailable, but he did want more P-39s and didn't ask for P-40s. He did mention the inability to reach the high flying Japanese, true with the P-40s also. As far as the First Team book, there were several P-39s and P-400s with the Cactus Air Force. There was mention of their lack of performance at altitude but nothing more other than they participated often on ground attack and some escort missions. No derogatory comments about their performance. 

What is confusing is that they were not dogs. Comparing the performance of the P-39D with the other players in that theater, the P-40E, F4F-4, and the Zero, the P-39 was faster than all, maybe equal to the P-40 at SL, up to 25,000 ft. ( some 15 to 30 mph faster than the Zero), and it could out climb all, except the exceptional Zero, from SL to 25,000 ft. except being equal to the F4F-4 at 25k. It also would beat all except the Zero to 20k in time to climb.
Data from America's Hundred Thousand and test results. 

So, why did the P-39 get such a bad reputation? I can think of only one real reason. Pilots, which may have come straight out of pilot training, were not trained in utilizing the speed ability of the aircraft, ala, P-40 pilots. From AHT, the word was stay under 15000 and above 300 mph and the Zero couldn't get you, ie, you could break off any time. even at 20k, the P-39 had a 30 mph speed advantage over the Zero. At 25k, it only had an 18 mph advantage over the Zero.


----------



## Shortround6 (Apr 10, 2020)

See post #2 from April 6th through the 23rd the XP-39 racked up hour and 40 minutes in the air, how much damage was involved when the nose wheel failed, I don't know. Somewhere in the first two months the engine was pulled because Allison needed the supercharger gears for a type test on another engine, this grounded the XP-39 until a replacement engine could be provided. I will try to look it up tomorrow. 
The XP-39 didn't do a lot flying between first flight and being shipped to Langley. The chronic overheating certainly didn't help.


----------



## wuzak (Apr 10, 2020)

Shortround6 said:


> See post #2 from April 6th through the 23rd the XP-39 racked up hour and 40 minutes in the air, how much damage was involved when the nose wheel failed, I don't know. Somewhere in the first two months the engine was pulled because Allison needed the supercharger gears for a type test on another engine, this grounded the XP-39 until a replacement engine could be provided. I will try to look it up tomorrow.
> The XP-39 didn't do a lot flying between first flight and being shipped to Langley. The chronic overheating certainly didn't help.



Certainly doesn't sound like high speed runs were that likely.


----------



## fastmongrel (Apr 10, 2020)

GregP said:


> If you believe solely in theory, a bumblebee should not be able to fly, but it does somehow, and with little seeming difficulty.



In theory a Bumblebee can fly incredibly well. The French Entomologist August Magnan was the one who said Bumblebees can't theoretically fly. An Aerodynamacist would have seen straight away that Bumblebees don't fly like birds, for a start they beat their four wings 230 times a second. If I could flap my arms as fast I could probably fly.

Bumblebee flight


----------



## b0ned0me (Apr 10, 2020)

davparlr said:


> What is confusing is that they were not dogs. Comparing the performance of the P-39D with the other players in that theater, the P-40E, F4F-4, and the Zero, the P-39 was faster than all, maybe equal to the P-40 at SL, up to 25,000 ft. ( some 15 to 30 mph faster than the Zero), and it could out climb all, except the exceptional Zero, from SL to 25,000 ft. except being equal to the F4F-4 at 25k. It also would beat all except the Zero to 20k in time to climb.
> ....
> So, why did the P-39 get such a bad reputation? I can think of only one real reason.


Another possible reason is that the P39 was supposed to be the latest greatest wholly uncompromised land fighter and yet had barely any superiority over a warmed-up re-engined previous generation design and an almost contemporary (but older) design labouring under the necessary compromises of carrier operation. 
If the P39 had been a successful design it should have comfortably bested the P-40 and F4F at all heights on every performance metric, and had a decisive edge in combat. It didn’t, as far as I am aware.


----------



## P-39 Expert (Apr 10, 2020)

wuzak said:


> Hi Greg,
> 
> While documents may have existed that showed the XP-39 doing 390mph, and those documents disappeared at some point, there was never a document that says that the XP-39 *didn't* do 390mph.
> 
> ...


Birch Matthews in his book "Cobra! Bell Aircraft Corp 1934-1946" states "Top speed was apparently somewhere around 375mph, perhaps a bit more, but less than the oft reported max speed of 390mph. The latter speed (390mph) appears to be strictly based on calculations. No performance results seem to have survived from this era. In fact it is doubtful that a complete development flight test program of the prototype XP-39 was ever formally completed." 

The XP-39 first flew on April 6, 1939. The nose gear broke on April 23rd after a total flying time of 1 hour and 40 minutes. By June 6 it was in the Langley wind tunnel. In addition to the nose gear failure there was persistant oil overheating. Not much time for official performance tests.


----------



## P-39 Expert (Apr 10, 2020)

davparlr said:


> I am also in a confused state about the P-39. I just got through reading the book "The First Team and the Guadalcanal Campaign" and I had read General Kenney's report relative to the fighting on New Guinea. Both time periods were similar and there was overlapping missions. Relative to the P-39, General Kenney wanted more of them, he preferred the P-38, but they were unavailable, but he did want more P-39s and didn't ask for P-40s. He did mention the inability to reach the high flying Japanese, true with the P-40s also. As far as the First Team book, there were several P-39s and P-400s with the Cactus Air Force. There was mention of their lack of performance at altitude but nothing more other than they participated often on ground attack and some escort missions. No derogatory comments about their performance.
> 
> What is confusing is that they were not dogs. Comparing the performance of the P-39D with the other players in that theater, the P-40E, F4F-4, and the Zero, the P-39 was faster than all, maybe equal to the P-40 at SL, up to 25,000 ft. ( some 15 to 30 mph faster than the Zero), and it could out climb all, except the exceptional Zero, from SL to 25,000 ft. except being equal to the F4F-4 at 25k. It also would beat all except the Zero to 20k in time to climb.
> Data from America's Hundred Thousand and test results.
> ...


We had three fighters in frontline service in all of 1942 until the P-38 entered combat in December. The Navy had the F4F Wildcat and the AAF had the P-39 and P-40. Their main adversaries in the Pacific were the A6M2 Zero and the Ki-43 Oscar who had very similar performance to each other.

AHT is a great book, but a lot of information has surfaced in wwiiaircraftperformance.org since AHT was published in 1999. Official performance charts show that the P-39D/F/K/L of 1942 with the early 8.8 geared Allisons were indeed faster at all altitudes than the F4F, P-40E/K/L and the Zero/Oscar. Their critical altitudes were all around 15000'. The F4F did about 320mph, the Zero about 330mph, the P-40 about 340mph and the P-39 about 370mph with those speeds falling off above critical altitude at about the same rates. On paper the P-39 had a 40mph speed advantage over the Zero above critical altitude.

The P-39 also outclimbed the other American planes. Versus the F4F the P-39 had a 500fpm advantage at 12000' which narrowed to about the same as the F4F at 25000'. P-40 climb was about the same as the F4F at 12000' then a steady 300fpm less than the F4F on up to their operational ceilings (1000fpm) around 23000'. The Zero outclimbed the three American planes substantially climbing at about 1850fpm at 20000' while the F4F/P-39 were making about 1200fpm and the P-40 about 900fpm at that altitude. After the 3000rpm climb limit was raised from 5 minutes to 15 minutes in mid '42 the P-39 and Zero climb rates were about the same at 20000'. Merlin P-40F/L had approximately the same performance as the P-39.

So the P-39 was 40mph faster than the Zero and could climb with it. Why wasn't it's record against the Japanese better? Two reasons:

1. Pilot training/quality. The IJN Zero pilots were the best in the world at the time. Plucked from elementary school and continuously trained to be fighter pilots flying the most maneuverable fighter of the time. Experience from their war with China and their late '41/early '42 conquests. Rigorous training and combat experience. That the Navy with their overmatched F4F did as well as they did against the Zero is the result of THEIR excellent training. Navy pilots graduated with over 600 flying hours as compared to their AAF counterparts with only 200 hours. They had the training and discipline to engage the Zero only when they had the altitude advantage.
2. Drop tanks: A 110 gallon drop tank on an already overweight 7650# P-39 meant that at normal power 2600rpm the combat ceiling (1000fpm) was about 18000'. IJN G4M bombers came in at between 18000' and 22000' with Zero escort a couple thousand feet above them. The P-39s with drop tank couldn't reach the bombers or their escort. Without a drop tank the P-39 could climb to 22500' easily at normal power (2600rpm) and well above that at combat power (3000rpm). But interception missions were normally flown with the drop tank since their normal mission was escort of C-47s or bombers. If on an alert for an interception mission the drop tanks were in place, but if for whatever reason the alert was cancelled they could go ahead and fly their normal escort mission. After altitude was reached the tanks would only be dropped at the start of their attack run. Virtually every P-39 mission was with drop tanks. Hardly any F4F missions carried drop tanks. The 1942 P-39 was good at escorting bombers and transports at medium altitude with a drop tank and was a good interceptor at higher altitudes without a drop tank. But they always carried the tank.

Reactions: Like Like:
2 | Informative Informative:
3 | Like List reactions


----------



## varsity07840 (Apr 10, 2020)

GregP said:


> Hi Wuzak,
> 
> Yes, I'm looking for proof, like anyone interested in what happened. You, me, or anyone else claiming something didn't happen is no proof one way or the other. If there was a test, it is likely recorded somewhere. So, I'm hoping the test document surfaces sometime. Otherwise, there is no point discussing the XP-39 peformance with just opinions. Everyone has one.
> 
> ...


By 1942, the Germans were flying Bf 109Fs and Gs, so a comparison to the Bf 109E is meaningless. The Soviet Air Force was strictly a tactical air arm. The P-39 suited THEIR requirements. The P-39 was intended to be an interceptor and in that role it failed miserably. If the P-39N was fine for service in the Pacific, why was it replaced with P-38s and P-47s? The 35th Fighter Squadron's P-39s were replaced in mid 1943 by P-40Ns, not P-39Ns. The pilots were glad to get them.

Reactions: Like Like:
1 | Like List reactions


----------



## GregP (Apr 10, 2020)

Hi Varsity,

It was replaced in Pacific service largely by the P-38 because: 1) the P-38 was withdrawn from the ETO and they were available, 2) The P-38 offered the over-water advantage of a second engine to get you home, and 3) There was no real point in having the extra logistics chain all over, so P-39s that remained were grouped together logically as everyone might expect.

The P-47 began to replace the P-39 when it came into general service. If was newer, much longer range than the P-39, hit harder, and was a much better overall airplane. For the first time, they could get to and fight at higher altitudes.

A comparison to the Bf 109E is not anywhere near meaningless. The Bf 109E and the P-39 were frequent antagonists in the Med and African desert areas. The Bf 109E was flown by the Germans well into the war on all fronts. You don't retire an early to mid-life fighter simply because a newer one becomes available. You retire them as they break down, need overhaul, or get lost in action. The Germans never had enough fighters and they would not waste a Bf 109E without a good reason.

In mid-1943, the 35th did get P-40Ns. Their P-39's were worn out or near it. Any new plane would have been good, and the P-40 was a bit better in some ways than the P-39. They had about the same speed and the P-40 likely handled better and probably handled rough fields better. But it certainly didn't outclimb the P-39 below 16,000 feet and moving from a tricycle gear to a conventional gear aircraft surely caused a few landing accidents. I bet the 35th hadn't landed a taildragger in a couple of years! The Allison in the P-40 was also much easier to work on than in the P-39. They surely didn't miss the driveshaft coming through their legs. They might have missed the cannon when strafing ships, but it jammed fairly readily ... so maybe not.

Reactions: Like Like:
2 | Like List reactions


----------



## XBe02Drvr (Apr 10, 2020)

varsity07840 said:


> The P-39 was intended to be an interceptor and in that role it failed miserably.


As mentioned by P39Expert above, the P39D's combat performance as an interceptor was primarily established on New Guinea and Guadalcanal, where it was handicapped most of the time by being configured for its other mission, bomber escort, lugging a 110 gallon drop tank around. Additionally, it oten suffered from lack of reliable early air raid warning, dictating an engagement from a climb underneath the raiders. No time and altitude to get accelerated to combat speed and no initial altitude advantage. Sitting Duck City.
Cheers,
Wes

Reactions: Agree Agree:
1 | Like List reactions


----------



## tomo pauk (Apr 10, 2020)

GregP said:


> Hi Varsity,
> 
> It was replaced in Pacific service largely by the P-38 because: 1) the P-38 was withdrawn from the ETO and they were available, 2) The P-38 offered the over-water advantage of a second engine to get you home, and 3) There was no real point in having the extra logistics chain all over, so P-39s that remained were grouped together logically as everyone might expect.
> 
> The P-47 began to replace the P-39 when it came into general service. If was newer, much longer range than the P-39, hit harder, and was a much better overall airplane. For the first time, they could get to and fight at higher altitudes.



P-38 was not withdrawn from ETO. Availability was a factor of Lockheed managing to make more P-38s by every new day.
P-39 was loathed by Gen Kenney since it was of too short a range (Kenney didn't rate the P-40 very high either), so it got to go away once better A/C were available. Introduction of P-38s meant an extra logistic chain, with or without the P-39.



> A comparison to the Bf 109E is not anywhere near meaningless. The Bf 109E and the P-39 were frequent antagonists in the Med and African desert areas. The Bf 109E was flown by the Germans well into the war on all fronts. You don't retire an early to mid-life fighter simply because a newer one becomes available. You retire them as they break down, need overhaul, or get lost in action. The Germans never had enough fighters and they would not waste a Bf 109E without a good reason.



Why not leveling the playing field - comapring the new P-39 vs. a new German or Italian fighter?


----------



## GregP (Apr 10, 2020)

Yes, Tomo, most of the P-38s were withdrawn from the ETO except for a small number. Most went to the Med and PTO, as you well know. Only a comparatively few stay in Europe. And you are missing my point about the P-38 and logistics. There was no use keeping the P-39s at the same base as the P-38s because they'd have to support two logistics chains. So, rather naturally, the P-39s that remained were grouped together to minimize the logistics, for the most part. Yes, there were exceptions to almost any policy or rule, as you well know.

I'm not talking about leveling the playing field at all, Tomo. I'm talking about the aircraft that were actually there. The P-39s and P-40s in the Med and Africa were not factory-new examples. They got what they could get because the primary fronts were elsewhere. Sure, the P-39s and P-40s fought Bf 109Fs and Gs, but they fought a heck of a lot of Bf 109E's, too. As I said, the Luftwaffe didn't retire a Bf 109E for no good reason. Neither did the Allies retire our fighters before their time. As for new Italian fighters, there were very few, but they did, in fact exist, so they might have showed up. They built 1,150 MC.202s and a whole 262 MC.205s. I'd say they ran across German fighters much more often, but I'm sure there were Italians fighters there, at least up until 8 Sep 1943 when Italy signed the Armistice and ceased combat. We were still flying older P-39s in the Med when there were no more Italian fighters flying anywhere on combat missions.


----------



## varsity07840 (Apr 10, 2020)

GregP said:


> Yes, Tomo, most of the P-38s were withdrawn from the ETO except for a small number. Most went to the Med and PTO, as you well know. Only a comparatively few stay in Europe. And you are missing my point about the P-38 and logistics. There was no use keeping the P-39s at the same base as the P-38s because they'd have to support two logistics chains. So, rather naturally, the P-39s that remained were grouped together to minimize the logistics, for the most part. Yes, there were exceptions to almost any policy or rule, as you well know.
> 
> I'm not talking about leveling the playing field at all, Tomo. I'm talking about the aircraft that were actually there. The P-39s and P-40s in the Med and Africa were not factory-new examples. They got what they could get because the primary fronts were elsewhere. Sure, the P-39s and P-40s fought Bf 109Fs and Gs, but they fought a heck of a lot of Bf 109E's, too. As I said, the Luftwaffe didn't retire a Bf 109E for no good reason. Neither did the Allies retire our fighters before their time. As for new Italian fighters, there were very few, but they did, in fact exist, so they might have showed up. They built 1,150 MC.202s and a whole 262 MC.205s. I'd say they ran across German fighters much more often, but I'm sure there were Italians fighters there, at least up until 8 Sep 1943 when Italy signed the Armistice and ceased combat. We were still flying older P-39s in the Med when there were no more Italian fighters flying anywhere on combat missions.


You sir, don't know what you are talking about. Your faulty contentions are too many to refute, but are faulty none the less.


----------



## jetcal1 (Apr 10, 2020)

varsity07840 said:


> You sir, don't know what you are talking about. Your faulty contentions are too many to refute, but are faulty none the less.


Please pick a few and refute away!

Reactions: Like Like:
2 | Like List reactions


----------



## XBe02Drvr (Apr 10, 2020)

jetcal1 said:


> Please pick a few and refute away!


With legitimate references!


----------



## Shortround6 (Apr 10, 2020)

GregP said:


> the P-38 was withdrawn from the ETO and they were available,


In late 1942 the P-38s in England were sent to North Africa, none of the P-38s in England were sent to the Pacific. Attrition In North Africa was high. Lockheed could barely keep up with supplying North Africa. A trickle went to the Pacific. All of the ones going to the Pacific came from the United States. Pacific Squadrons did not get hand-me-downs from England or North Africa/Italy. Lockheed production was kind of up and down from month to month in 1942 and most of 1943 but the last 3 months of 1943 saw production roughly double. 1054 planes built in the last 3 months compared to 1443 for the previous 9 months. Production in 1944 was almost exactly the total number built in 1941, 42 and 43 put together. The P-38s sent to England in the fall of 1943 stayed in England, they were just transferred from the 8th AIr Force to the 9th Air Force as more P-51s arrived. When these P-38s left England in 1944/45 they went to France, not to Italy or the CBI or the Pacific. 

One has to be careful when talking about the P-38 being withdrawn from the ETO, They were withdrawn from the 8th AIr Force twice, once to go to North Africa for operation Torch and the 2nd time they didn't really change location, they just changed command structure. 

As far as the 109E goes. It is quite possible the P-39 did fight some 109Es in North Africa, but I doubt there were very many. The P-39 shows up in NA during Torch just after Torch I don't think any were shipped around Africa or flown across Africa? Two P-39 fighter groups, the 81st and the 350th fly from England to North Africa in Jan 1943, at which point the newest 109-Es anywhere would be 1 1/2 to two years old. You can't really combine 109Es and Fs in a squadron or group (perhaps the group?) because the performance is so different. Some 109Es may have been being used as fighter bombers in Jan of 1943? By April of 1943 the Free French are being given P-39s. By May of 1943 the 350th group is assigned patrol duty in Algiers west of Spanish Morocco.

Reactions: Like Like:
2 | Agree Agree:
1 | Informative Informative:
1 | Like List reactions


----------



## XBe02Drvr (Apr 10, 2020)

varsity07840 said:


> You sir, don't know what you are talking about. Your faulty contentions are too many to refute, but are faulty none the less.


And you, sir, are being unnecessarily insulting to an informed and long respected member of our community.
There are plenty of less dismissive ways to present a disagreement over factual information. Like citing source data. And explaining how it led to whatever your conclusions are.
Cheers,
Wes

Reactions: Agree Agree:
6 | Like List reactions


----------



## FLYBOYJ (Apr 11, 2020)

I suggest some folks chill out!

Reactions: Agree Agree:
4 | Like List reactions


----------



## XBe02Drvr (Apr 11, 2020)

FLYBOYJ said:


> I suggest some folks chill out!


Roger. Read you 5 square. Wilco.

Reactions: Like Like:
1 | Like List reactions


----------



## GregP (Apr 11, 2020)

Hi Varsity,

I suppose we read different books ... but the war is over and we know the outcome. I don't really want to pursue nitpicking. 

I just love the aircraft. They are fun to work on and see fly. Cheers.

Reactions: Like Like:
3 | Friendly Friendly:
2 | Like List reactions


----------



## varsity07840 (Apr 11, 2020)

jetcal1 said:


> Please pick a few and refute away!


Why did Spitfires replace P-39s when the 31st FG got to England?
Name one front line German JG that was flying 109Es in 1943
P-39s, P-40s and P-38s were at the same bases in the Pacific all the time. Ever heard of Port Moresby or Henderson Field?


----------



## jetcal1 (Apr 11, 2020)

varsity07840 said:


> Why did Spitfires replace P-39s when the 31st FG got to England?
> Name one front line German JG that was flying 109Es in 1943
> P-39s, P-40s and P-38s were at the same bases in the Pacific all the time. Ever heard of Port Moresby or Henderson Field?



Please feel free to continue. I'm particularly enjoying the tone of your response. (Hint, hint.)

Reactions: Like Like:
2 | Like List reactions


----------



## XBe02Drvr (Apr 11, 2020)

varsity07840 said:


> Why did Spitfires replace P-39s when the 31st FG got to England?
> Name one front line German JG that was flying 109Es in 1943
> P-39s, P-40s and P-38s were at the same bases in the Pacific all the time. Ever heard of Port Moresby or Henderson Field?


I'm with jetcal; please continue. But bear in mind, this forum is not a troll hole. There's a lot of accumulated knowledge and experience here to be shared with you, if you're willing to treat people in a civil manner, and they will do the same for you. If you're looking to polish your ego with your scholarly prowess, this is not the place to do it.
Now let's hear your description of the events of Port Moresby and Henderson Field, with squadrons, aircraft types, dates of tours of duty for each, and combat performance and kill/loss success rates. Don't forget relative effectiveness of aircraft types on both sides, and of course, cite your sources.
This has all been hashed out thoroughly over the years, and we'd be interested to see what new info you bring to the table.
"Over!"
Cheers,
Wes

Reactions: Like Like:
2 | Like List reactions


----------



## varsity07840 (Apr 11, 2020)

XBe02Drvr said:


> I'm with jetcal; please continue. But bear in mind, this forum is not a troll hole. There's a lot of accumulated knowledge and experience here to be shared with you, if you're willing to treat people in a civil manner, and they will do the same for you. If you're looking to polish your ego with your scholarly prowess, this is not the place to do it.
> Now let's hear your description of the events of Port Moresby and Henderson Field, with squadrons, aircraft types, dates of tours of duty for each, and combat performance and kill/loss success rates. Don't forget relative effectiveness of aircraft types on both sides, and of course, cite your sources.
> This has all been hashed out thoroughly over the years, and we'd be interested to see what new info you bring to the table.
> "Over!"
> ...


My comment about different aircraft at Port Moresby and Henderson field was in response to his comments that P-39s and P-38s would not be kept at the same airfields because it would mean supporting two logistics chains. I don't need to polish my ego, but since you asked, Ill give you an example several logistics chains. In the 5th AF at Port Moresby, by early 1943, the 7th and 8th fighter squadrons had P-40Es and P-40Ks. The 9th FS had P-38Fs. The 39th Fs had P-38Fs. The 40th and 41st FSs had a mix of P-400s, P-39Ds and P-39Fs. The 35th and 36th FS had a mix of P-400s and P-39D-1s. The 80th FS had P-38Fs. I've no intention of relating the history of the air war in the pacific for you. Perhaps you need to pursue some sources assuming that there was no sarcasm in your comment. There is no new info to bring to the table. Only the difference between fact and conjecture. 
Cheers.

Reactions: Like Like:
1 | Like List reactions


----------



## GregP (Apr 11, 2020)

To be fair to Varisty, the Bf 109E was generally being phased out by late 1941, true. But "being phased out" doesn't mean you scrap all of them overnight and replace them all at the same time wholesale. The German aircraft industry wasn't that good at production. All told, they made some 3,478 Bf 109E's including E1, E-3, E-4, E-5, and E-7 models. The entire German Messerschmitt Bf 109 production for 1942 was 2,658 aircraft so, even if they replaced a Bf 109E every single time they could do it, as soon as the new Bf 109F / G was built, they probably couldn't convert everyone by the end of 1942, despite the losses in the Spanish Civil War and early WWII. I bet every forward unit had at least some if not a majority of newer models by the end of 1942, but let's face it, the Mediterranean Theater wasn't exactly the number one priority for either the Allies or the Axis. The "new" F's went to the units defending the Reich first, and the Russian Front, which opened just before the F's came out for deployment to front-line units.

So, I'd bet some E models soldiered on unless worn out until sometime in 1943. No, I don't have the Luftwaffe unit aircraft on hand by type and date and doubt anyone else does off the top of their head either. When the P-51D came out, there were many units that flew the B/C and D/K together for quite a long time. Ditto with bubble-top Thunderbolts. Yes, they were replaced with newer planes, but not all at once at the same time. The only time a unit got wholesale replacement was when the unit converted to a new type. If the went from, say P-38s to P-51s, they'd get an entire batch of P-51s all at once or nearly at once because they were converting from one type to another. Otherwise, they'd get replacements as they became available from production and their allocation priority got to the top of the stack.

The Germans sometimes converted from the Bf 109 to the Fw 190, and then, the unit might get an entire batch of Fw 190s, which freed up the replaced Bf 109s for re-deployment to units still flying the Bf 109. Erich Hartmann's favorite aircraft model was the Bf 109F and he stayed with the Bf 109 even when he was specifically asked to convert to the Fw 190. His reasoning was that someone familiar with an aircraft was better able to survive than someone who was a veteran, but just getting used to a new aircraft model. His superiors agreed. He flew his Bf 109F well past the time when it should have been traded for a Bf 109G, according to several articles I read in the past, and according to Erich himself when he visited the American Aces Association in Mesa, Arizona in the 1980s. He finally did trade for a later model 109 when his F became battle-weary. If I remember correctly, he traded his F for a G in fall 1944. The F's SHOULD have been gone earlier, but he liked the lighter weight of the F over the much heavier G.

As for the P-38s getting transferred, Jimmy Doolittle asked for an RAF evaluation of U.S. Fighters. It is well documented that Eric Brown was instrumental in these evaluations and stated that the Fw 190 could hit Mach 0.75 in a dive but the P-38 was constrained to Mach 0.68. making it “useless” in Europe. After the evaluation tests at Farnborough, the P-38 was kept in fighting service in Europe for only a little while longer. By September 1944, all but one of the P-38 groups had converted to P-51s. The last P-38 group flew F-5 PR Lightnings. This wasn't in 1943, but they DID get transferred out of the ETO except for photo-recce versions by Sep 1944. There were at least two P-38 groups transferred to North Africa in 1942 - early 1943, including the 1st, 14th, and 82nd. The 1st and 14th were sent in Nov 42 and the 82nd was sent to replace the depleted P-38s of 1st and 14th somewhat later, if you check.

Last, about the logistics, what I should have said was that one Group would NOT fly mixed aircraft for long due to the two logistics chains. They might be at the same field, but one Fighter Group flew one aircraft type out of pure logic and the otherwise stupid logistics chains. There would also be the need to have pilots, mechanics, and mission planners trained on both types, which was just stupid to consider unless there were some other glaring reason for doing so.


----------



## jetcal1 (Apr 11, 2020)

BF109E-4/B W. Nr. 5580 (Built in 1940) was in service at least until February 24th 1942 in Norway as that is the date that Uffz Hunold made a navigational error and ended up in a forced landing on Lake Balivik which was frozen at the time.
Also consider a BF109-F4 forced landed in Sweden on 9 October 1943 which was a year and a half after the G-2 entered service and 6 weeks after a BF-109G-6. (Which was a new production aircraft at the time.)
The Navalized BF-109T-1/2 also remained in service until the summer of 1944 with 11./JG 11 in Norway

Romania was still using the BF-109E In June 1942.

Reactions: Informative Informative:
1 | Like List reactions


----------



## FLYBOYJ (Apr 12, 2020)

GregP said:


> one Group would NOT fly mixed aircraft for long due to the two logistics chains.



Not nitpicking but you did have Composite Groups in the AAF during WW2 where several different types of aircraft were operated at the squadron level within the group.


----------



## drgondog (Apr 12, 2020)

FLYBOYJ said:


> Not nitpicking but you did have Composite Groups in the AAF during WW2 where several different types of aircraft were operated at the squadron level within the group.




Very True Joe - that said composite operations were almost always a.) very early in the war on places like Guadalcanal where they fought with what they had, r b.) during transition - say from P-47s or P-38s to Mustangs. Mid war in CBI and Pacific, there were still mixed P-39/P-40 and P-40/P-38 composite groups with mixed squadrons. Logistics and spares and 'interchangeability of pilot and parts' nightmares.

Reactions: Like Like:
1 | Informative Informative:
1 | Like List reactions


----------



## drgondog (Apr 12, 2020)

As I read through this the one over riding thought about the XP-39 is that it was not a very good fighter as built. Kelsey wrote the specs but he was very disappointed in the performance and room for growth into a viable high altitude capable Pursuit aircraft. It was "the Small Solution' compared to the XP-38. It was always cursed with marginal stability, short range and crappy altitude performance (Allison issue, however). 

Bell just never did develop either experimental or production aircraft considered better than average (except by 1943 VVS standards) - nobody even claims that either the X-1 or X-1A were 'great'. That changed with Bell Helicopter due largely to Bart Kelley post WWII.


----------



## GregP (Apr 12, 2020)

Hi guys,

I'm sure the composite groups were operated but, as stated above, not for long periods. When transitioning types, there is almost always a small overlap. But they wouldn't want the overlap to last for longer than necessary unless there was a specific reason for retaining the old type. I'm sure they might retain a different type as a squadron hack or some other reason. The U.S.A. used several German and Japanese types as squadron hacks or the "commander's plane," including the A6M5 Model 52 Zero that the Planes of Fame now flies. It was a commander's plane for some time on the west coast after the war, but they did that during the war, too. Some U.S. and British units operated Seibel Si.204s during the war when they became available as Luftwaffe fields were overrun. I'd bet some might have wanted to operate enemy fighters, but it would be too easy to get shot down by friendly fire if you were in an armed aircraft and the war was still in full swing, friendly markings notwithstanding.

I'm really not trying to make this into a life story of the Bf 109E or F timeline. Just saying that combat aircraft have a lifespan, and they aren't usually retired until that life span is used up or some other operational reason takes an older aircraft out of service. And ... I did say *usually*. There are exceptions to almost any rule, even when we don't really want exceptions. I'd think the E's could have been retired by the end of 1942, but probably not ALL of them. We have had several speakers and visitors at the Planes of Fame who said they flew P-39s into late-war, but I'm sorry to say I don't recall the units involved. It didn't seem important at the time ...


----------



## FLYBOYJ (Apr 12, 2020)

GregP said:


> Hi guys,
> 
> I'm sure the composite groups were operated but, as stated above, not for long periods.


Greg - composite groups were operated in one form or another throughout the war. I believe there were 8 or 9 of them, the most famous was the 509th Composite group, operated Silverplate B-29s and C-54s. The 342nd Composite Group operated for over 2 years and operated at least 4 different types of aircraft. 342nd Composite Group (USAAF). Composite groups operated in the post war and I believe there were a few operated during the Korean War.


----------



## GregP (Apr 12, 2020)

Hi,

So, that seems like a deliberate decision to operate a composite group for a specific reason, not an across-the-board haphazard mix of aircraft. I'm sure heavy bombers take many heavy spare parts and having some tramspoprts makes keeping everything running a LOT easier than waiting for somebody else to fly them in.

When I was in the Air Force at Ellsworth in South Dakota, we had a B-52 wing, but we also operated KC-135s and had two semi-permanent T-33s. The B-52 and KC-135 mix makes good sense, and the T-33s were not really often-used, but enough to see them every once in a while.

Reactions: Like Like:
1 | Like List reactions


----------



## FLYBOYJ (Apr 12, 2020)

GregP said:


> Hi,
> 
> So,* that seems like a deliberate decision to operate a composite group for a specific reason*, not an across-the-board haphazard mix of aircraft. I'm sure heavy bombers take many heavy spare parts and having some tramspoprts makes keeping everything running a LOT easier than waiting for somebody else to fly them in.
> 
> When I was in the Air Force at Ellsworth in South Dakota, we had a B-52 wing, but we also operated KC-135s and had two semi-permanent T-33s. The B-52 and KC-135 mix makes good sense, and the T-33s were not really often-used, but enough to see them every once in a while.



Exactly, but I think some of the Composite units in WW2 existed more out of operational necessity rather than a strategic plan. In the case of the 509th, the supporting C-54s made perfect sense considering what the Group's primary mission was.

Reactions: Agree Agree:
1 | Like List reactions


----------



## Shortround6 (Apr 12, 2020)

Some of this depends on the theater and the time. In the SW Pacific you were going to get composite groups/wings because you didn't have enough of any type of aircraft. 

Two 3 squadron groups each with mixed aircraft or 3-5 understrength groups each with one-two squadrons of identical aircraft? 
This was pretty much the situation in NA after Torch with composite wings, not enough groups with identical aircraft to form a wing unless it was a two group wing. 

How low you can go depends on the aircraft (and personnel) as trying to operate at squadron level with different types of aircraft (P-40s and P-38s) isn't going to work well in the air, maintenance and supply being a whole different tissue. However certain models of different aircraft are somewhat interchangeable. P-40Ks and Ms? Or P-40Es and Ks ? certain P-39s or even some P-38s could be plugged into a squadron without much disruption. Certain planes could not, P-40F&Ls not only have to be kept separate form other P-40s for maintenance reasons but trying to fly a mixed squadron above 15,000ft would be horror show. 

Same with th e109s, you might be able to mix Fs & Gs at certain times but Es and Fs are not going to work in the same squadron, their flight characteristics are too different, A fighter group might very well have several squadrons of FGs and one of Es for a period of time however.

Reactions: Agree Agree:
1 | Like List reactions


----------



## GregP (Apr 12, 2020)

I'm not too sure about the mixed operation being difficult. Here is a clip of the Planes of Fame Airshow in 2012 with two P-51s (Merlin variety) and our P-38. They didn't seem to have any trouble. Two four-bladed Merlins and two three-bladed Allisons together. Of course, they weren't in a combat situation, either. But Steve Hinton (in the P-38) wasn't babying the Allisons.

Reactions: Like Like:
2 | Disagree Disagree:
1 | Like List reactions


----------



## BiffF15 (Apr 12, 2020)

GregP said:


> I'm not too sure about the mixed operation being difficult. Here is a clip of the Planes of Fame Airshow in 2012 with two P-51s (Merlin variety) and our P-38. They didn't seem to have any trouble. Two four-bladed Merlins and two three-bladed Allisons together. Of course, they weren't in a combat situation, either. But Steve Hinton (in the P-38) wasn't babying the Allisons.




Greg,

What’s the difference between babying the motors and not babying them? I’m assuming he flew at the higher of the speeds required for over the top maneuvers while still leaving his wingmen a little something power wise to stay in formation.

Cheers,
Biff


----------



## wuzak (Apr 12, 2020)

In WW2 the combination wouldn't work so well as the cruise conditions would not be the same for both aircraft.

One would be at less than optimum performance.

Reactions: Agree Agree:
2 | Like List reactions


----------



## Shortround6 (Apr 13, 2020)

At a Modern airshow the Merlins are going to be in low gear. (unless your air show is several thousand feet higher than Denver), Likewise the P-38s turbo (if the airshow planes even have them, yours may, some do not.) are going to be idling or near idle. The show has been carefully choreographed and practiced so the pilots know about what throttle settings to use to maintain their formation, On a given day they may need to make minor adjustments. Part of what separates those pilots from the also rans and wannabees. 

But airshows at low altitude don't tell us what the planes were going to be doing at 20, 000ft and up or how different planes with different speeds, climb performance, dive speeds and turning radius are going stay together with out the whole formation having to conform to worst parts of each different types flight envelope.

Reactions: Agree Agree:
1 | Like List reactions


----------



## rinkol (Apr 13, 2020)

GregP said:


> I have seen I said in here that there is no way the XP-39 went 390 mph, but have seen no proof of same except for some various quoting of poorly-documented wind tunnel testing done on the machine either before or after the turbocharger was deleted. The posters don’t bother to say. There is, however, some considerable second-tier sources that say otherwise.
> There is a digitized NACA report (Engineer in Charge: A History of Langley Aeronautical Laboratory 1917 – 1958) which states that the XP-39 DID achieve 390 mph using 1,150 hp @ 20,000 feet. But, it did so at a gross weight of 5,550 lbs at takeoff.
> 
> URL: Engineer in charge .
> .



I'm skeptical about the 390 mph claim. As others have mentioned, there were aerodynamic and engine installation issues. Moreover, in this time period it was quite common for manufacturers (and governments) to exaggerate performance claims. Also, many claims were based on calculations. Thee were quite a few experimental planes that never came anywhere close to the calculated or specified performance figures. The British were very disappointed with the P-39s that they ordered - I recall reading that Bell eventually admitted their performance figures were obtained with a stripped machine.

Reactions: Agree Agree:
1 | Like List reactions


----------



## XBe02Drvr (Apr 13, 2020)

rinkol said:


> in this time period it was quite common for manufacturers (and governments) to exaggerate performance claims.


It would be SO easy to position your static ports in spots that are low pressure areas at max speed AOA to gain optimistic airspeed readings. While this wouldn't survive rigorous testing (NACA), it could be used to favourably impress potential buyers evaluation pilots. Just the sort of stunt Larry Bell would be attracted to.
Cheers,
Wes


----------



## Mal H (Apr 13, 2020)

GregP said:


> Hi Old Jim,
> 
> Very true. The wartime "experts" never flew the plane with the ammunition completely expended.
> 
> ...



I was one of the participants in the 1970s P-39 tumbling study. And yes it was totally an unofficial and unfunded test. But now everyone involved is either retired or passed on, so no one can get in trouble, but it can be good lesson on how sometimes historic research gets done. At the time I was an aerodynamics engineer at Beech Aircraft involved in new aircraft development and as part of my job I did both flight testing and wind tunnel testing including many spin tunnel tests at Langley. I studied aviation history both as a hobby and to gain knowledge and data for my vocation of engineering. A friend of mine, who was also an aeronautical engineer and history buff, had been doing research on the P-39 stories of tumbling. He had gone thru the old Wright Field reports and noted that they had seen no tendency of the aircraft to tumble, but he also noted that the flight testing was all done with an equivalent full mass of ammunition in the nose and full fuel. He had interviewed several P-39 combat veterans and they had indicated to him that the tumbling occurred on the return from combat missions when the ammunition had been expended and fuel burned off. He asked me if I had at looked at the NACA P-39 spin tunnel test data? I told him yes, but only from the point of view of the effect of the door opening and of the pilot escape path. But I also informed him I had a spin tunnel test to do at NASA Langley in a few weeks and would ask see the P-39 test data while I was there. My NASA friends pulled the P-39 test file for me and the NACA spin tunnel test had been done at a request from the AAF which called out the test requirements. The AAF had only requested testing at full gross weight and that was all that was done. There was no sign of tumbling seen. Now one has to remember that in WWII the Langley tunnels were running 7 days a week, three shifts a day, so there was little time was for exploring outside the formal test request. During a coffee break in the spin tunnel conference room, I brought up the P-39 tumbling. The NASA engineers got interested and also read the file. Now in the 1970’s, the offices, hallways, and conference room in the spin tunnel building all had old spin tunnel models hanging from the ceilings. Now it just so happened one of the models hanging in the conference room was the P-39. Also Jim Bowman, head of the spin tunnel at that time was in on the coffee break and mentioned that in WWII he had been an apprentice in the model shop where the P-39 model was constructed. Well as you probably know engineers and wind tunnel technicians are nothing but over aged little boys, thus a plan was formed to refurbish the P-39 model and test it in those other flight conditions. Of course this was all done on lunch hours and coffee breaks! A few check points were made at the gross weight loadings which repeated the original WWII tests. The model was then reballasted to simulate no nose ammunition and low fuel and retested. And with this loading the P-39 model would sometimes tumble.

Reactions: Bacon Bacon:
6 | Like Like:
5 | Agree Agree:
1 | Winner Winner:
5 | Informative Informative:
2 | Like List reactions


----------



## BiffF15 (Apr 13, 2020)

Mal H said:


> I was one of the participants in the 1970s P-39 tumbling study. And yes it was totally an unofficial and unfunded test. But now everyone involved is either retired or passed on, so no one can get in trouble, but it can be good lesson on how sometimes historic research gets done. At the time I was an aerodynamics engineer at Beech Aircraft involved in new aircraft development and as part of my job I did both flight testing and wind tunnel testing including many spin tunnel tests at Langley. I studied aviation history both as a hobby and to gain knowledge and data for my vocation of engineering. A friend of mine, who was also an aeronautical engineer and history buff, had been doing research on the P-39 stories of tumbling. He had gone thru the old Wright Field reports and noted that they had seen no tendency of the aircraft to tumble, but he also noted that the flight testing was all done with an equivalent full mass of ammunition in the nose and full fuel. He had interviewed several P-39 combat veterans and they had indicated to him that the tumbling occurred on the return from combat missions when the ammunition had been expended and fuel burned off. He asked me if I had at looked at the NACA P-39 spin tunnel test data? I told him yes, but only from the point of view of the effect of the door opening and of the pilot escape path. But I also informed him I had a spin tunnel test to do at NASA Langley in a few weeks and would ask see the P-39 test data while I was there. My NASA friends pulled the P-39 test file for me and the NACA spin tunnel test had been done at a request from the AAF which called out the test requirements. The AAF had only requested testing at full gross weight and that was all that was done. There was no sign of tumbling seen. Now one has to remember that in WWII the Langley tunnels were running 7 days a week, three shifts a day, so there was little time was for exploring outside the formal test request. During a coffee break in the spin tunnel conference room, I brought up the P-39 tumbling. The NASA engineers got interested and also read the file. Now in the 1970’s, the offices, hallways, and conference room in the spin tunnel building all had old spin tunnel models hanging from the ceilings. Now it just so happened one of the models hanging in the conference room was the P-39. Also Jim Bowman, head of the spin tunnel at that time was in on the coffee break and mentioned that in WWII he had been an apprentice in the model shop where the P-39 model was constructed. Well as you probably know engineers and wind tunnel technicians are nothing but over aged little boys, thus a plan was formed to refurbish the P-39 model and test it in those other flight conditions. Of course this was all done on lunch hours and coffee breaks! A few check points were made at the gross weight loadings which repeated the original WWII tests. The model was then reballasted to simulate no nose ammunition and low fuel and retested. And with this loading the P-39 model would sometimes tumble.



Excellent information, thanks for posting!

Reactions: Agree Agree:
1 | Like List reactions


----------



## GregP (Apr 14, 2020)

Hi Biff,

By "not babying the Allisons," I mean Steve was sometimes pulling 55"+ MAP. Not always, of course, but I'm assuming when they went vertical on the way up from less-than-high airspeed. The P-38 will outclimb the P-51 at lower altitudes, but not likely from low-but-identical airspeeds. I rather doubt the P-51's were babying their Merlins, either when looping from airshow airspeeds. Neither was either type using even full military power in the airshow clip. After all, they weren't exactly flying with 145 performance number fuel. I doubt if anyone in the formation was pulling more than about 1,000 - 1,100 hp.

As for the comment about what it doesn't show (not yours, Biff), what it clearly tells me is the dissimilar aircraft have no problems flying formation. Our fighters cruise to airshows and other public displays together routinely in formation, and they don't have any trouble. We have even had a P-47, P-38, and P-51 information with an F-22, and THEY didn't have any trouble with it, either.




In fact, I have never heard any of our pilots, speakers, or visitors say they had any trouble flying in formation with another aircraft type. Not sure where the notion they would have trouble staying in formation with dissimilar aircraft would even come from.

I'm sure they wouldn't do it for extended periods unless there was a reason to do so, but the capability is certainly there. Liquid-cooled inline fighters would probably have trouble flying for extended periods at 185 mph (plug fouling), but the radials would have little difficulty cruising at 250 - 280 mph except for the extra fuel consumption. They certainly have the ability to cruise with one another for some time, should the need arise, regardless of altitude, unless you happen to be right at the altitude where a supercharger in one of the birds changes gears automatically.

I'd place a bet that Biff flew formation in an F-15 with something other than another F-15 at some point.

Mal H, THANK YOU for posting!

Reactions: Disagree Disagree:
1 | Like List reactions


----------



## wuzak (Apr 14, 2020)

GregP said:


> As for the comment about what it doesn't show (not yours, Biff), what it clearly tells me is the dissimilar aircraft have no problems flying formation. Our fighters cruise to airshows and other public displays together routinely in formation, and they don't have any trouble. We have even had a P-47, P-38, and P-51 information with an F-22, and THEY didn't have any trouble with it, either.



Greg, it's all well and good in an airshow setting. 

There is a video on the web showing a Sopwith Pup (or Camel, can't recall exactly) flying in formation with a Spitfire. The Sopwith was flying near its maximum speed and the Spitfire was just above stall.

In the WW2 context, the USAAF would often escort their PR Mosquitoes (F-8/PR.XVI) with P-51s (B or D). The range that the missions could take was compromised because the speed at which the Mosquito and the P-51 could achieve that range was quite a bit different.

By speeding up the P-51s and slowing down the Mosquito a compromise was achieved, but the range of the mission was reduced.

And both those aircraft used 2 stage Merlins, though their best altitude range was different, the Mosquito's 70 series engines having a higher FTH than the P-51's V-1650-7s (Merlin 65/66).

Reactions: Informative Informative:
1 | Like List reactions


----------



## wuzak (Apr 14, 2020)

Also why escort missions in the ETO were flown in relays.

Reactions: Agree Agree:

1 | Like List reactions


----------



## GregP (Apr 14, 2020)

Wuzak,

While the normal cruise of a P-51 was about 275 mph, a P-51 didn't have to speed up to cruise with a Mosquito. Mostly the 275 mph cruise speed of the P-51 was to allow it to zig-zag above the bombers to it could stay with them. A P-51D/K had a range of 1100 miles at a speed of 395 mph at 2400 rpm according to the 1944 pilot's manual charts from this forum. Of course, that was not the optimum range for the P-51D/K, but it COULD do it. The 275 mph was the best bomber escort cruise. Heck, it can go 1,500 miles at 370 mph at 2,500 rpm with 269 gallons of fuel on board.

P-51 Cruise Speed = 395 mph TAS

Perhaps I am misreading the manual.

The typical Mosquito wasn't going to do that. Normal cruise was about 295 mph and could go to 325 mph and later 360 mph or so. Yes, it could go faster, but not at cruise speed. Anything over 340 mph was getting into shorter ranges unless you had a specific type, like maybe a 1945 NF. Mk 30. It COULD cruise at 364 mph at 27,500 ft, but max speed was 397 mph at best altitude and the range at 360 mph wasn't all that great. There really weren't all that many Mosquitos that could hit much more than low 400 mph. 

The F Mk. II could hit 358 mph. The NF Mk. XV could hit 408 mph or so. The B Mk. IX could hit right at 405 mph. The FB Mk. VI could hit 368 mph or so. The IV could hit 367 - 380 mph depending on the exhaust stub. The PR Mk. XVI could hit 401 mph. These are all maximum speeds in FS gear and optimum altitudes. Any MS gear speed was 15 - 20 mph slower. Yes, it was a fast, amazing airplane, particularly when cruising into hostile airspace, but not faster than a P-51 if the P-51 wanted to fly that fast. 

I'll give you this, the Mosquito at optimal cruise was faster than a P-51 at best range cruise. But unless the mission was farther than Berlin and back, the P-51 had plenty of speed and range to stay with a Mosquito. Of course, there wasn't as much room in the P-51 cockpit and the P-51 engine-out performance was nowhere NEAR the Mosquito's.

Reactions: Disagree Disagree:
1 | Like List reactions


----------



## P-39 Expert (Apr 14, 2020)

Mal H said:


> I was one of the participants in the 1970s P-39 tumbling study. And yes it was totally an unofficial and unfunded test. But now everyone involved is either retired or passed on, so no one can get in trouble, but it can be good lesson on how sometimes historic research gets done. At the time I was an aerodynamics engineer at Beech Aircraft involved in new aircraft development and as part of my job I did both flight testing and wind tunnel testing including many spin tunnel tests at Langley. I studied aviation history both as a hobby and to gain knowledge and data for my vocation of engineering. A friend of mine, who was also an aeronautical engineer and history buff, had been doing research on the P-39 stories of tumbling. He had gone thru the old Wright Field reports and noted that they had seen no tendency of the aircraft to tumble, but he also noted that the flight testing was all done with an equivalent full mass of ammunition in the nose and full fuel. He had interviewed several P-39 combat veterans and they had indicated to him that the tumbling occurred on the return from combat missions when the ammunition had been expended and fuel burned off. He asked me if I had at looked at the NACA P-39 spin tunnel test data? I told him yes, but only from the point of view of the effect of the door opening and of the pilot escape path. But I also informed him I had a spin tunnel test to do at NASA Langley in a few weeks and would ask see the P-39 test data while I was there. My NASA friends pulled the P-39 test file for me and the NACA spin tunnel test had been done at a request from the AAF which called out the test requirements. The AAF had only requested testing at full gross weight and that was all that was done. There was no sign of tumbling seen. Now one has to remember that in WWII the Langley tunnels were running 7 days a week, three shifts a day, so there was little time was for exploring outside the formal test request. During a coffee break in the spin tunnel conference room, I brought up the P-39 tumbling. The NASA engineers got interested and also read the file. Now in the 1970’s, the offices, hallways, and conference room in the spin tunnel building all had old spin tunnel models hanging from the ceilings. Now it just so happened one of the models hanging in the conference room was the P-39. Also Jim Bowman, head of the spin tunnel at that time was in on the coffee break and mentioned that in WWII he had been an apprentice in the model shop where the P-39 model was constructed. Well as you probably know engineers and wind tunnel technicians are nothing but over aged little boys, thus a plan was formed to refurbish the P-39 model and test it in those other flight conditions. Of course this was all done on lunch hours and coffee breaks! A few check points were made at the gross weight loadings which repeated the original WWII tests. The model was then reballasted to simulate no nose ammunition and low fuel and retested. And with this loading the P-39 model would sometimes tumble.


Excellent first hand information, thanks for posting. It was also said that no tumbling was possible during normal flight or landing even with nose ammo expended. The plane needed to stall at a high AOA at near vertical. Did your test verify that? Thanks again.


----------



## P-39 Expert (Apr 14, 2020)

drgondog said:


> As I read through this the one over riding thought about the XP-39 is that it was not a very good fighter as built. Kelsey wrote the specs but he was very disappointed in the performance and room for growth into a viable high altitude capable Pursuit aircraft. It was "the Small Solution' compared to the XP-38. It was always cursed with marginal stability, short range and crappy altitude performance (Allison issue, however).
> 
> Bell just never did develop either experimental or production aircraft considered better than average (except by 1943 VVS standards) - nobody even claims that either the X-1 or X-1A were 'great'. That changed with Bell Helicopter due largely to Bart Kelley post WWII.


Disagree with you on the crappy altitude performance. 

The N model (produced Dec '42-April '43) had a service ceiling of 38,500', a combat ceiling (1000fpm) of 31000' and a climb rate of 2650fpm at 20000'. Most other contemporary (late '42-early '43) fighters climbed at only about 2000fpm at 20000' including the P-38F/G, P-47 (not even in combat yet), P-51A, Hellcat (not even in combat yet), Corsair, Typhoon, FW190 and Zero. The Me109G could climb with the P-39N and of course the Spitfire IX outclimbed everything in the sky. None of these planes (except P-51A) was considered a low altitude plane.

Despite going all the way through the Q model designation, there were really only two production P-39 models: D/F/K/L with the earlier Allison models -35 and -63 with the 8.8 supercharger gears and the later M/N/Q with the later (late '42) Allison -83 and -85 with the higher rated 9.6 gears. Airframes were the same, differences included propellers, reduction gears, armament, radios and (different models of the Allison) engines. Of the 9500+ P-39s built, over 7000 had the higher rated 9.6 geared engines from late '42.

The earlier D/F/K/L models with the 8.8 engines were low/medium altitude planes but could match the N model in climb if their weight was reduced from standard 7650# to around 7200# which was easily done by removing the .30 caliber wing guns (200#) and the extreme nose armor plate (100#) and a few other unnecessary items. But, in their standard configurations at 7650# they had a very difficult time reaching high altitude (over 20000') with their ubiquitous 110gal drop tanks. Reduce the weight to 7200# and that restriction goes away.

Reactions: Like Like:
1 | Like List reactions


----------



## wuzak (Apr 14, 2020)

GregP said:


> Wuzak,
> 
> While the normal cruise of a P-51 was about 275 mph, a P-51 didn't have to speed up to cruise with a Mosquito. Mostly the 275 mph cruise speed of the P-51 was to allow it to zig-zag above the bombers to it could stay with them. A P-51D/K had a range of 1100 miles at a speed of 395 mph at 2400 rpm according to the 1944 pilot's manual charts from this forum. Of course, that was not the optimum range for the P-51D/K, but it COULD do it. The 275 mph was the best bomber escort cruise. Heck, it can go 1,500 miles at 370 mph at 2,500 rpm with 269 gallons of fuel on board.





> Watton was covered with a thin layer of snow as they took off at 0920 in NS569. Prior arrangements were made to rendezvous at 0925 with four P-51s from 20th FG at 18,000 feet over Cromer. They would provide escort to Stettin and return.
> 
> The Mosquito met the fighter escort as planned; but now heavily loaded with l,000 gallons of fuel, flew at a severe speed disadvantage. Geary attempted to maintain economical cruising speed but outpaced the P-51s and was forced to throttle-back to continue flying formation with them. The Mustangs had long-range drop tanks and were also fully loaded. Once involved with enemy action, they would jettison their tanks, and therefore, were attempting to conserve and obtain maximum range from their fuel supply. This exacerbated the problem. It was a very-long flight to the Polish border, and on three occasions Geary throttled-back and did not receive the mileage planned.



German Jet Encounters

I have doubts that a P-51 could cruise at 370mph for 1,500miles. Looking at the manual, it says 1,040 miles at that cruise condition. 1,600 miles could be achieved with 419 USG of fuel.

The PR.XVI could carry 760 UKG (912 USG) internally and 100 UKG (120 USG) in wing fairing (drop) tanks. A total of 860 UKG (1,032 USG). A PR.XVI could go a long way, especially at best economical speed.




GregP said:


> The typical Mosquito wasn't going to do that. Normal cruise was about 295 mph and could go to 325 mph and later 360 mph or so. Yes, it could go faster, but not at cruise speed. Anything over 340 mph was getting into shorter ranges unless you had a specific type, like maybe a 1945 NF. Mk 30. It COULD cruise at 364 mph at 27,500 ft, but max speed was 397 mph at best altitude and the range at 360 mph wasn't all that great. There really weren't all that many Mosquitos that could hit much more than low 400 mph.



I didn't say a "typical" Mosquito. I said a PR.XVI Mosquito, which can carry a shit load of fuel without drop tanks.

Low 400mph range, fully loaded, for B and PR Mosquitoes. 

The point is that the PR.XVI could carry the bulk of its fuel in the regular tanks and in bomb bay auxiliary tanks.




GregP said:


> The F Mk. II could hit 358 mph. The NF Mk. XV could hit 408 mph or so. The B Mk. IX could hit right at 405 mph. The FB Mk. VI could hit 368 mph or so. The IV could hit 367 - 380 mph depending on the exhaust stub. The PR Mk. XVI could hit 401 mph. These are all maximum speeds in FS gear and optimum altitudes. Any MS gear speed was 15 - 20 mph slower. Yes, it was a fast, amazing airplane, particularly when cruising into hostile airspace, but not faster than a P-51 if the P-51 wanted to fly that fast.



The F.II and FB.VI had single stage engines. The fighters/fighter/bombers also suffered more drag due to the flat windscreen, so were slower than the equivalent bomber version.

The NF.XV had extended wing tips for high altitude operation, but they never went into service. And there were only a handful of them built.

Reactions: Winner Winner:
1 | Like List reactions


----------



## BiffF15 (Apr 14, 2020)

GregP said:


> Hi Biff,
> 
> By "not babying the Allisons," I mean Steve was sometimes pulling 55"+ MAP. Not always, of course, but I'm assuming when they went vertical on the way up from less-than-high airspeed. The P-38 will outclimb the P-51 at lower altitudes, but not likely from low-but-identical airspeeds. I rather doubt the P-51's were babying their Merlins, either when looping from airshow airspeeds. Neither was either type using even full military power in the airshow clip. After all, they weren't exactly flying with 145 performance number fuel. I doubt if anyone in the formation was pulling more than about 1,000 - 1,100 hp.
> 
> ...




Greg,

Good info, which leads me to more questions surprisingly enough! If pulling 55’ of MAP is pushing the engines (today’s fuels), then what is the normal range on an Allison or Merlin? Does your guys (POF) P38 have the turbos operating?

The comment about dissimilar formation flying alludes to what’s called wingman consideration. I would bet the the P38 can loop at a lower speed than the Mustangs, therefore the 38 pilot must fly his aircraft inside the Mustangs parameters (above his min loop airspeed) when going over the top (looping). The 38 has centerline thrust with both engines operating and a thicker wing allowing for a slower loop than the Mustang (guess on my part). 

In addition to making sure your “flight” has enough speed to accomplish a maneuver, you may have to add some additional speed / power to insure your wingmen are going fast enough to have good flying quality for their respective planes. Too mushy on the stick adds danger and looks bad. Too fast and wingys can’t keep up (get spit out on outside of turn).

I have flown close with F111, F16, F18, F4, KC135, KC10, B1, RC26, Mig29, F14 and I’m sure others (while in the Eagle). First time was at Red Flag as a wingman in the Eagle. I got split from my flight lead and was a RTB. Flowed into one of the arrival corridors, and spot a pair of F111s. I’m thinking great, one of them is a flight lead and I will join up and go back with them (lowers the odds I will screw up the arrival or go to the wrong runway). Well I form up with them and they pass me the lead. WTF! So I lead them back, checking out their plane the whole way (had not been up close to one) thinking they wanted me to lead so they don’t screw it up! Hah. I needed to lead it because my overhead (360 overhead in civilian speak) was smaller and faster, which would get all three of us on the ground that much faster (pattern gets very busy during a Red Flag recovery). We were told we could/ should do this (much more efficient) but had, up to this point, not done anything the first time without having been instructed in it.

And I still had to face the debrief to answer how I got split from my lead (Jobu). Those were some fun days.

Cheers,
Biff

Reactions: Bacon Bacon:
2 | Like Like:
1 | Like List reactions


----------



## GregP (Apr 14, 2020)

Hi Biff!

WWII engines are surprisingly reliable. I worked the Planes of Fame airshows for more than 10 years and we generally flew three days (Fri, Sat, Sun) with something like 65 - 70 sorties per day. We had a VERY low rate of problems. Did we have issues? Sure.

Figure 50 sorties per day for 3 days to be conservative. That's 150 sorties per airshow for 10 years. 1500 sorties. I recall 1) one Corsair that couldn't get one wing to fold down, 2) a flat tire, 3) A Grumman F3F that backfired during landing and blew the crankcase gaskets out (dropped oil everywhere), and 4) a couple of aborted takeoffs due to a rough engine. That's around 5 aborts in 1500 sorties, or about 0.3% aborts. Pretty good! I might have missed a few more, but not many. So, these engines are NOT fragile.

Typically, they use some decent power for takeoff / Initial climb, and then throttle back for economy. The government isn't paying for fuel. Steve Hinton told me he doesn't shy away from using 2,000 Hp on takeoff in a Bearcat or other R-2800 aircraft, but not for extended periods. A clip below shows him doing some aerobatics in a Tigercat. Listen and tell me he's not running the R-2800s above cruise power!



In our P-38, we are not running the turbos. They are installed but non-operational. I know of only one P-38 currently running the turbos at this time, but I suppose there could be more than one. I don't keep up with the current population's configurations too often except for knowing most of the Allisons rather intimately. All but one or two are flying Joe Yancey engines. The Red Bull units is flying Allisons from Bud Wheeler. In a stock P-38, the little scoop on the side of the boom near the trailing edge is the turbocharger air intake . Since the Planes of Fame ins't running the turbos, they have that blocked off and the carburetor intake feeds from the center of the boom-front airscoop intake. The outer two boom-front air intake sections feed the oil coolers as expected.

As for the Allison operation in the P-38, the "normal" military max was about 1100 HP / 2600 rpm at sea level AND at 30,000 feet, 57" MAP. Steve might pull that or close to it briefly during a vertical climb for maybe 5 - 10 seconds or so and then throttle back on the way down because there isn't any reason to rawhide the engines unnecessarily. Then again, he might leave power in it all the way around. I have not flown a fighter through a vertical maneuver and don't know for sure. I have ridden in a P-51 through a loop / roll, but confess I wasn't watching the throttle at the time. Power WAS added for the loop, but we also got some airspeed from a slight dive to start. These aircraft normally cruise at economy settings and only throttle up for takeoff and airshow maneuvers to keep them safe on vertical lines. Mostly, they don't fly aerobatics. I'd say most flights might see a 3 - 4 G break or two, possibly more Gs than that, but very few flights actually see much in the way of aerobatics. Usually, that is for airshows and maybe the occasional dogfight with a friend. If you fly a private fighter as a civilian, I'm sure the temptation to play is occasionally overwhelming. Maybe you can expand on that a bit. Our museum pilots generally fly these aircraft to not stress the engines / airframes too much and not use excessive fuel without a good reason. An airshow aerobatic demo is one good reason, and they DO practice enough to maintain safety and a low-altitude waiver when they do airshow aero.

Below is an example of an airshow crash at Biggin Hill when the P-63 pilot didn't throttle up to do a safe vertical maneuver. He basically pulled up from low-cruise power, stalled or maybe just torqued around at the top with low airspeed. He had plenty of power on tap but didn't use it, and did sort of a lazy semi-spin into the ground.



To be safe, you need the proper speed and power setting for the maneuver you are doing. But you are a fighter pilot and rather obviously KNOW that. I doubt you'd try a vertical maneuver in an F-15 without adding some thrust to keep airspeed. Maybe you can expand a bit on airshow F-15 power settings for vertical maneuvers from level flight.

Reactions: Like Like:
1 | Like List reactions


----------



## BiffF15 (Apr 14, 2020)

GregP said:


> Hi Biff!
> 
> WWII engines are surprisingly reliable. I worked the Planes of Fame airshows for more than 10 years and we generally flew three days (Fri, Sat, Sun) with something like 65 - 70 sorties per day. We had a VERY low rate of problems. Did we have issues? Sure.
> 
> ...




Greg,

In the T38 we would use military power / 500kts and 10k above you to do a loop. IIRC we were at about 250 going over the top. In burner it would loop in about 3500-4000’ and have about 200-230 over the top. Lots more buffet as you pulled a good bit harder. In the Eagle at airshows the vertical climb was done in full burner and max deflection (or close to it) aileron rolls. It would go straight up to about 20k (from sea level) before you had to pull over the top (at as low as 200kts or so). Do that climb without the aileron rolls and you could go up into the 40’s. I did it, rolled out at 43000 and accelerated thru the Mach. Lots of drag when doing full lateral rolls. If at a lower fuel weight and no external tanks you could go over the top with as low as 200 kts. Looping is a much cleaner maneuver than going over the top. One is done for fun, the other to win a fight.

There was no pushing the engines in the Eagle. You used AB (afterburner) when required. You could go full AB on takeoff and not pull it out until fuel dictated, and the motors would shrug it off. FADECs are PFM (pure effing magic).

The POF has some great maintenance with that low of an abort rate! What I meant about pushing the motors was, is there a band that’s used under normal circumstances, say 30-50 MAP, and for other times they are pushed higher? Lookin for actual numbers if you have them.

Cheers,
Biff

Reactions: Bacon Bacon:

2 | Like List reactions


----------



## GregP (Apr 14, 2020)

Thanks, Biff!

When "social distancing" is over, I'll ask Steve about the Allison and Merlin numbers for normal flying.

Reactions: Like Like:
1 | Like List reactions


----------



## Mal H (Apr 16, 2020)

P-39 Expert said:


> Excellent first hand information, thanks for posting. It was also said that no tumbling was possible during normal flight or landing even with nose ammo expended. The plane needed to stall at a high AOA at near vertical. Did your test verify that? Thanks again.


It has been too many years gone by and I do not remember the exact flight conditions from which we saw tumbling. But in the spin tunnel the aircraft starts out at 90 degrees angle of attack and decreases down until it reaches a spin (or in this case tumble) or if not flys out.


----------



## Venturi (Apr 16, 2020)

Great info. Thanks Mal, Biff, GregP and others who have great first hand experience.

I suspect that the MAP chosen in "power needed" situations is due to the fuel used, is that right Greg? 55" or so for the Allison at 3000 with 100 PN to avoid detonation?

I have a question / statement re 8.8 gear s/c P-39. Is there any evidence these a/c used greater than 100PN fuel? If so, what PN fuel did they have access to? I have a reason for asking...


----------



## Shortround6 (Apr 16, 2020)

Venturi said:


> Is there any evidence these a/c used greater than 100PN fuel




Little, if any, 150 or 115-145 fuel showed up in the Pacific, at least until the last few months of the war.

Unfortunately nobody was keeping really good records of 100PN fuel in the early part of the war. Or even most of the war. 

When the US switched to "100" fuel it was 100 octane (the PN scale didn't exist yet) and since the US specified not more than 2% aromatics a lot of the US fuel was 100/98-99 to 100/100+ when later tested. This was in 1939-40. The British 100 "octane" during the BoB was 100/115 to 100/120 depending on batch, Until the PN scale was invented there was no way to test it or rate it. There may have been an interim 100/125 fuel, at least several Allisons were rated on it. The US and British got together and came up with a specification for a common fuel with a rating of 100/130, By the end of 1942, beginning of 1943 they were on their *3RD* specification for 100/130 PN fuel, each different specification had different limits for allowable quantities of lead and some other changes like amounts of certain kinds of aromatic compounds and volatility ( how well the fuel evaporates at low temperatures). But all three were known as 100/130 fuel and since by 1942/43 there was no other kind of 100/--- fuel in use anywhere many reports just use 100 as a shorthand for the 100/130 fuel. 

I have no doubt that many P-39s with 8.80 gears ran on 100/130 in both the Pacific and in NA and Italy.

Reactions: Like Like:
1 | Agree Agree:
1 | Informative Informative:
1 | Like List reactions


----------



## GregP (Apr 16, 2020)

There is a nice story of detonation with Allisons early in their deployment to Europe. It was eventually traced to the difference in aromatics in gasoline. Basically, the Allisons were jetted at the factory using U.S. fuel (2% aromatics) and were thus improperly jetted for the British fuel (20% aromatics). It took a short while for this to be "discovered." When it was found, the issue was rather quickly corrected, resulting in better-running Allisons in Europe. After that, the issue never resurfaced.

By the time Merlins were being built in the U.S.A., the aromatic thing was past, and they were never mis-jetted from the factories. 

There were a number of early "stumbling blocks" to U.S. mission in the ETO. They were eventually all ironed out. All sides had stumbling blocks and we have had many threads about it. The Germans ironed out theirs in the Spanish Civil War. The British started out the war flying in Vic formation, and didn't switch to finger-four until later when the advantages of it became obvious. So, we tried things our way at first and found out for ourselves what worked and what didn't, just as the other air forces had.

Reactions: Like Like:
1 | Like List reactions


----------



## wuzak (Apr 16, 2020)

So British fuel was to blame for problems with the Allison early in the war and failures in late model P-38s late in the war?

Reactions: Bacon Bacon:
1 | Like List reactions


----------



## Venturi (Apr 17, 2020)

What failures in the late P-38 are you referring to, wuzak?


----------



## wuzak (Apr 17, 2020)

> Arrival of the newer P-38J to fill in behind the P-38H was supposed to help, but did not help enough. The J model’s enlarged radiators were trouble-prone. Improperly blended British fuel exacerbated the problems: Anti-knock lead compounds literally seethed out and became separated in the Allison’s induction system at extreme low temperatures. This could cause detonation and rapid engine failure, especially at the high power settings demanded for combat.



Why the P-38 Flunked in Europe


----------



## varsity07840 (Apr 17, 2020)

P-39 Expert said:


> Disagree with you on the crappy altitude performance.
> 
> The N model (produced Dec '42-April '43) had a service ceiling of 38,500', a combat ceiling (1000fpm) of 31000' and a climb rate of 2650fpm at 20000'. Most other contemporary (late '42-early '43) fighters climbed at only about 2000fpm at 20000' including the P-38F/G, P-47 (not even in combat yet), P-51A, Hellcat (not even in combat yet), Corsair, Typhoon, FW190 and Zero. The Me109G could climb with the P-39N and of course the Spitfire IX outclimbed everything in the sky. None of these planes (except P-51A) was considered a low altitude plane.
> 
> ...



Climb rate aside, what was the max speed of the P-39N vs. the P-47D, P-51B/D/K, P-38J/L at the altitudes required for bomber escort? What was the P-39N's radius of action after getting to escort altitude? With regard to weight savings on earlier models, given the P-39's poor air to air armament, one would think that removal of the 37mm gun the archaic sychronised .50s and the would be the first step. But that wasn't possible because the aircraft was designed around nose armament particularly the cannon. Removal would affect the cg, just the way expended ammo did. Removal of the nose guns on the P-40 caused no such problems. So, what you would end up with is two slow firing .50 cal guns and a cannon that was totally unsuited for fighter vs fighter combat. Yes, the Russians made good use of the P-39 in that configuration, but I doubt if you could have found an American pilot of that era who would prefer to fight with that type of armament.

Reactions: Like Like:
1 | Like List reactions


----------



## varsity07840 (Apr 17, 2020)

GregP said:


> There is a nice story of detonation with Allisons early in their deployment to Europe. It was eventually traced to the difference in aromatics in gasoline. Basically, the Allisons were jetted at the factory using U.S. fuel (2% aromatics) and were thus improperly jetted for the British fuel (20% aromatics). It took a short while for this to be "discovered." When it was found, the issue was rather quickly corrected, resulting in better-running Allisons in Europe. After that, the issue never resurfaced.
> 
> By the time Merlins were being built in the U.S.A., the aromatic thing was past, and they were never mis-jetted from the factories.
> 
> There were a number of early "stumbling blocks" to U.S. mission in the ETO. They were eventually all ironed out. All sides had stumbling blocks and we have had many threads about it. The Germans ironed out theirs in the Spanish Civil War. The British started out the war flying in Vic formation, and didn't switch to finger-four until later when the advantages of it became obvious. So, we tried things our way at first and found out for ourselves what worked and what didn't, just as the other air forces had.



Packard started building V-1650-1s in 1941, and V-1650-3 powered P-51Bs were in production in 1943, well before the P-38s problems with fuel, among other things, came to light. The aromatic thing was not past. It hadn't been discovered yet. The V-1650 didn't have a problem with British fuel to begin with and apparently either did the R-1820, R-1830 and R-2800, all of which were pre war designs when the use of British fuel was not even considered. It was solely an Allison problem. The suggestion that some sort of lesson was learned from the Allison problems and applied to V-1650 production doesn't add up.


----------



## Shortround6 (Apr 17, 2020)

wuzak said:


> Why the P-38 Flunked in Europe



It would be nice if that explanation was the right one but there is a lot wrong just in that short excerpt. 

Did the "new" radiators cause trouble or was it the new intercoolers?
Back to blaming the "British" fuel? Every refinery that made fuel made it in batches depending on what material were available and sometimes made several different batches in the same week. The fuel could actually be one of hundreds of different blends. There may have been bad fuel, it may have been available in England at the time, now try to trace it to a British Refinery. 
"Anti-knock lead compounds" there are a lot of anti-knock compounds used in fuel, like the up to 20 % aromatics, none of them are lead. Lead is an anti-knock compound but it is singular, not plural and was limited by specification to 4.6 cc per US gallon. 

I didn't read through the whole link to see if the author mentioned misrigged turbo and throttle controls or pilots not being taught the methods for cruising that BOTH Lockheed and Allison recommended.

Reactions: Agree Agree:
2 | Like List reactions


----------



## wuzak (Apr 17, 2020)

Just using it as an example of where British fuel was blamed for engine failures.


----------



## GregP (Apr 17, 2020)

Never said British fuels were to blame for late-model P-38 issues, Wayne, and you damned well know it. We've had this conversation before. The early P-38's had issues with the intake that was fixed with the turbulator-venturi inside the intake. They had issues with the 20% aromatic fuels. The fix took some 6+ months to iron out because the issue wasn't recognized at first. They had issues with the cockpit heater. The fix was a simple electric heater in the cockpit. And we had issues with training. That took experience and not flying into a combat zone with the engines at low cruise and the gunsights cold. They never DID fix the low critical Mach number.

You really need to stop trying to put words in other people's mouths, at least mine. If I'm trying to say something, I'll say it. If you want to say something, say it and take credit for it, but don't attribute it to me, OK?

As for when we made Merlins, the XP-51B didn't fly until Nov 1942 and the P-51B/C wasn't in production until after that. Meanwhile, the Merlins that were built here were built to British specifications until the USAAC/F started acquiring the P-51B/C. The P-51As didn't cause any issues at home because we were flying U.S. gasoline and didn't see the issue at all. There were many issues with making Merlins in the U.S.A., but the aromatic fuel thing wasn't really one of them. The Merlin issues were largely with transferring production and associated drawings ... normal start-up things for a new factory tooling up for an existing design.


----------



## BiffF15 (Apr 17, 2020)

I need a refresher on the P38 in ETO problems and timeline. I know it’s been discussed in here before, does anyone have a link?

Cheers,
Biff


----------



## Shortround6 (Apr 17, 2020)

Greg, please go over the time line for the P-38. There are two different issues with fuel at different times. 

The early US fuel had little or no aromatics, this was in 1940 or so, If you want 100/125 or 100/130 you have to use aromatics. At least if you want to make fuel on a large scale. 

When the Americans started to use the 20% (max it could be less) fuel there were all sorts of problems, including dissolving rubber parts in the fuel systems and self sealing tank liners, Jetting may very well have been a problem but the other problems were bigger. ALL of the problems were eventually solved. This is in regards to the early 100/130 fuel.

Early 100/130 fuel was limited to 3.0ccs of lead per US gallon and while there could be 20% aromatics in the fuel the types of aromatics may have been restricted. Use of aromatics is also restricted by the standard of BTUs per pound of fuel (18,700?) and most or all of the aromatics are lower than that so if you use too much of the aromatics in the blend you have somewhat lower than requirement heat value per pound. 

At some point in 1942 (early?) they decide that if they use 4.0 cc of lead per US gallon they can get a lot more 100/130 fuel from the same amount of base stocks so that is approved (after testing to see about lead fouling) and in late 1942 or early 1943 they decide they need a lot more 100/130 fuel and the way to do that is to allow 4.6cc of lead per gallon and allow more of the heavy aromatics but still not exceeding about 20% total. everybody knew that this "new" 100/130 might cause problems and the engine makers began testing it with the engines at the beginning of 1943. Allison found they did have troubles under certain conditions and started working on a new intake manifold in the spring of 1943. It was being fitted to engines and P-38s in either November or December of 1943 but since it takes weeks to get a P-38 From California to Europe all the planes in theater had the old manifolds. 
There may have been bad batches of fuel supplied to units in England, or batches of fuel that gave more trouble in P-38s than other aircraft. 

However the constant referral to "British" fuel may be a bit unfair. The Entire 8th and 9th Air Force were using British fuel? America was shipping no 100/130 fuel to England at this time? 

In any case, the switch from US 100 octane 2% aromatic fuel to the 20% aromatic fuel happened 1-2 years before the P-38 was used as escort by the 8th Air Force in 1943/44. 
In fact the British and Americans were on their 3rd joint specification for fuel (1=100/125, 2=100/130 3cc lead , 3=100/130 4cc lead) using 20% aromatic fuel when the P-38s were England before being sent to North Africa at the end of 1942. 

What the US was doing with old stocks of the 100 octane fuel with 2% aromatics at this time I have no idea, using it for training? sending it to engine makers to run in the engines with? 
Was it all used up by the end of 1942? I don't know and won't guess. There is certainly a possibility that engines were being jetted wrong.

There is also the fact that engines that were used for training in the US were jetted for (and used different ignition timing) to suit them for 91 or 91/96 fuel used the training commands. Strict track was supposed to be kept of where these engines went but........ who knows????

There is certainly room for confusion as there were so many different fuel blends all with the same "name"

Reactions: Agree Agree:
1 | Winner Winner:
1 | Informative Informative:
3 | Like List reactions


----------



## Venturi (Apr 17, 2020)

Single stage V-1710: options for improvements?

I like this post.


----------



## tomo pauk (Apr 17, 2020)

Venturi said:


> Single stage V-1710: options for improvements?
> 
> I like this post.



Cheers, Venturi.
Note that a lot of points (all of them?) listed there were not substantiated by a source.

Reactions: Agree Agree:
1 | Like List reactions


----------



## Venturi (Apr 17, 2020)

I don't think I see many sources posted on here. If you were made to post with reference sources such as in the scientific literature, then surely less unsubstantiated claims would be routinely made. But also, those who have knowledge and not too much time, would be posting less.

Cheers


----------



## tomo pauk (Apr 17, 2020)

Venturi said:


> I don't think I see many sources posted on here. If you were made to post with reference sources such as in the scientific literature, then surely less unsubstantiated claims would be routinely made. But also, those who have knowledge and not too much time, would be posting less.
> 
> Cheers



I'll wish you a good day then.


----------



## Shortround6 (Apr 17, 2020)

Sources include. 

Development of aircraft engines by Robert Schlaifer
Development of Aviation fuels by S.D.Heron
Aviation fuels and the effects on Engine Performance S.D. Heron
this last is also Navaer-06050501/USAF T.0. No. 06-5-4

and a few other books that mention aviation fuel.

Reactions: Like Like:
1 | Like List reactions


----------



## gjs238 (Apr 17, 2020)

varsity07840 said:


> Climb rate aside, what was the max speed of the P-39N vs. the P-47D, P-51B/D/K, P-38J/L at the altitudes required for bomber escort? What was the P-39N's radius of action after getting to escort altitude? With regard to weight savings on earlier models, given the P-39's poor air to air armament, one would think that removal of the 37mm gun the archaic sychronised .50s and the would be the first step. But that wasn't possible because the aircraft was designed around nose armament particularly the cannon. Removal would affect the cg, just the way expended ammo did. Removal of the nose guns on the P-40 caused no such problems. So, what you would end up with is two slow firing .50 cal guns and a cannon that was totally unsuited for fighter vs fighter combat. Yes, the Russians made good use of the P-39 in that configuration, but I doubt if you could have found an American pilot of that era who would prefer to fight with that type of armament.



RE: removal of the 37mm gun

From Bell P-39 Airacobra - Wikipedia 
_In 1940, the British Direct Purchase Commission in the U.S. was looking for combat aircraft; they ordered 675 of the export version Bell Model 14 as the "*Caribou*" on the strength of the company's representations on 13 April 1940. The British armament was two nose-mounted 0.50 in (12.7 mm) machine guns, and four 0.303 in (7.7 mm) Browning machine guns in the wings; the 37 mm gun was replaced by a 20 mm (.79 in) Hispano-Suiza cannon. _


----------



## varsity07840 (Apr 17, 2020)

GregP said:


> Never said British fuels were to blame for late-model P-38 issues, Wayne, and you damned well know it. We've had this conversation before. The early P-38's had issues with the intake that was fixed with the turbulator-venturi inside the intake. They had issues with the 20% aromatic fuels. The fix took some 6+ months to iron out because the issue wasn't recognized at first. They had issues with the cockpit heater. The fix was a simple electric heater in the cockpit. And we had issues with training. That took experience and not flying into a combat zone with the engines at low cruise and the gunsights cold. They never DID fix the low critical Mach number.
> 
> You really need to stop trying to put words in other people's mouths, at least mine. If I'm trying to say something, I'll say it. If you want to say something, say it and take credit for it, but don't attribute it to me, OK?
> 
> As for when we made Merlins, the XP-51B didn't fly until Nov 1942 and the P-51B/C wasn't in production until after that. Meanwhile, the Merlins that were built here were built to British specifications until the USAAC/F started acquiring the P-51B/C. The P-51As didn't cause any issues at home because we were flying U.S. gasoline and didn't see the issue at all. There were many issues with making Merlins in the U.S.A., but the aromatic fuel thing wasn't really one of them. The Merlin issues were largely with transferring production and associated drawings ... normal start-up things for a new factory tooling up for an existing design.





GregP said:


> Never said British fuels were to blame for late-model P-38 issues, Wayne, and you damned well know it. We've had this conversation before. The early P-38's had issues with the intake that was fixed with the turbulator-venturi inside the intake. They had issues with the 20% aromatic fuels. The fix took some 6+ months to iron out because the issue wasn't recognized at first. They had issues with the cockpit heater. The fix was a simple electric heater in the cockpit. And we had issues with training. That took experience and not flying into a combat zone with the engines at low cruise and the gunsights cold. They never DID fix the low critical Mach number.
> 
> You really need to stop trying to put words in other people's mouths, at least mine. If I'm trying to say something, I'll say it. If you want to say something, say it and take credit for it, but don't attribute it to me, OK?
> 
> As for when we made Merlins, the XP-51B didn't fly until Nov 1942 and the P-51B/C wasn't in production until after that. Meanwhile, the Merlins that were built here were built to British specifications until the USAAC/F started acquiring the P-51B/C. The P-51As didn't cause any issues at home because we were flying U.S. gasoline and didn't see the issue at all. There were many issues with making Merlins in the U.S.A., but the aromatic fuel thing wasn't really one of them. The Merlin issues were largely with transferring production and associated drawings ... normal start-up things for a new factory tooling up for an existing design.



Did you or did you not say that there was problems with the Allison in Europe relative to British fuel. Where did I say that you said that British fuel was responsible for the P-38's problems.


GregP said:


> Never said British fuels were to blame for late-model P-38 issues, Wayne, and you damned well know it. We've had this conversation before. The early P-38's had issues with the intake that was fixed with the turbulator-venturi inside the intake. They had issues with the 20% aromatic fuels. The fix took some 6+ months to iron out because the issue wasn't recognized at first. They had issues with the cockpit heater. The fix was a simple electric heater in the cockpit. And we had issues with training. That took experience and not flying into a combat zone with the engines at low cruise and the gunsights cold. They never DID fix the low critical Mach number.
> 
> You really need to stop trying to put words in other people's mouths, at least mine. If I'm trying to say something, I'll say it. If you want to say something, say it and take credit for it, but don't attribute it to me, OK?
> 
> ...



Did you or did you not say Allisons had detonation problems attributed to British fuel? No, you didn't say British fuel was responsible for P-38 issues, and I didn't say you did. You note the detonation problems and suggested that issues with British fuel were resolved before the Packard Merlin went into production, so Merlins produced weren't mis jetted in the factory. I take that to mean that based on experiences with the Allison, Packard took measures to ensure that they didn't have the same problems, what you refer to as mis jetting. That's just not the case, as I pointed out since V-1650s were in production well before the P-38H and J flew their first missions in Europe. How is that putting words in your mouth?

Reactions: Agree Agree:
1 | Like List reactions


----------



## Venturi (Apr 17, 2020)

Nose-mounted armament is inherently superior to wing mounted, from multiple points of view. Centerline-mounted weapons have no horizontal convergence issues, additionally wing-mounted weapons have significant dispersion when under any g loading which the centerline weapons do not Wing mounted weapons also increase the aircraft’s rotational intertia, (about the longitudinal axis) leading to slower aileron response. Yes, close inboard wing mountings reduce these problems, but only serve to prove the point.
Advantages with wing mounted weapons include greater space for multiple weapons and associated ammunition, less adverse CoG effects when ammunition is expended (variable), and no need for propeller synchronization.
By the way, the Germans found no issues with RoF reduction in centerline synchronized MG17 mounts... RoF somewhere around 1200RPM.


----------



## varsity07840 (Apr 17, 2020)

gjs238 said:


> RE: removal of the 37mm gun
> 
> From Bell P-39 Airacobra - Wikipedia
> _In 1940, the British Direct Purchase Commission in the U.S. was looking for combat aircraft; they ordered 675 of the export version Bell Model 14 as the "*Caribou*" on the strength of the company's representations on 13 April 1940. The British armament was two nose-mounted 0.50 in (12.7 mm) machine guns, and four 0.303 in (7.7 mm) Browning machine guns in the wings; the 37 mm gun was replaced by a 20 mm (.79 in) Hispano-Suiza cannon. _


The 37mm gun was replaced by a 20mm in the "Caribou"/Airacobra/P-400 and the P-39D1. That's a given. The nose cannon wasn't eliminated. It was replaced with a different one in those versions, again because cg issues demanded a gun or ballast be installed. In that case, you might as well install a gun.

Reactions: Agree Agree:
2 | Like List reactions


----------



## varsity07840 (Apr 17, 2020)

Venturi said:


> Nose-mounted armament is inherently superior to wing mounted, from multiple points of view. Centerline-mounted weapons have no horizontal convergence issues, additionally wing-mounted weapons have significant dispersion when under any g loading which the centerline weapons do not Wing mounted weapons also increase the aircraft’s rotational intertia, (about the longitudinal axis) leading to slower aileron response. Yes, close inboard wing mountings reduce these problems, but only serve to prove the point.
> Advantages with wing mounted weapons include greater space for multiple weapons and associated ammunition, less adverse CoG effects when ammunition is expended (variable), and no need for propeller synchronization.
> By the way, the Germans found no issues with RoF reduction in centerline synchronized MG17 mounts... RoF somewhere around 1200RPM.



Any synchronized gun will have a reduced rate of fire. The MG17 had a 1200 RPM rate WITHOUT synchronization. Axis fighters that retained synchronized weapons did so because their original wing designs prevented added guns or larger frame and or caliber guns from being installed without major redesign. The Bf-109 is a perfect example as was the P-39 for the allies. The Idea of a gondola mounted .50 on an American fighter in 1943 is ridiculous. And they were combined with synchronized nose guns and mandated cannon due to cg issues. The Germans and Russians did have better success with centerline cannon because their guns had a much better ROF.

Reactions: Agree Agree:
1 | Like List reactions


----------



## gjs238 (Apr 17, 2020)

varsity07840 said:


> The 37mm gun was replaced by a 20mm in the "Caribou"/Airacobra/P-400 and the P-39D1. That's a given. The nose cannon wasn't eliminated. It was replaced with a different one in those versions, again because cg issues demanded a gun or ballast be installed. In that case, you might as well install a gun.


Uh, yeah, that's what it says.


----------



## wuzak (Apr 17, 2020)

GregP said:


> Never said British fuels were to blame for late-model P-38 issues, Wayne, and you damned well know it. .



Maybe you didn't say it, but others have, evidenced by the article I quoted above.




GregP said:


> As for when we made Merlins, the XP-51B didn't fly until Nov 1942 and the P-51B/C wasn't in production until after that. Meanwhile, the Merlins that were built here were built to British specifications until the USAAC/F started acquiring the P-51B/C. The P-51As didn't cause any issues at home because we were flying U.S. gasoline and didn't see the issue at all. There were many issues with making Merlins in the U.S.A., but the aromatic fuel thing wasn't really one of them. The Merlin issues were largely with transferring production and associated drawings ... normal start-up things for a new factory tooling up for an existing design.



To be clear, Packard Merlins, at least the main production variants, were always built to Rolls-Royce specifications, and their power ratings were the same as the equivalent Rolls-Royce model.

Reactions: Agree Agree:
1 | Like List reactions


----------



## Venturi (Apr 17, 2020)

varsity07840 said:


> Any synchronized gun will have a reduced rate of fire. The MG17 had a 1200 RPM rate WITHOUT synchronization. Axis fighters that retained synchronized weapons did so because their original wing designs prevented added guns or larger frame and or caliber guns from being installed without major redesign. The Bf-109 is a perfect example as was the P-39 for the allies. The Idea of a gondola mounted .50 on an American fighter in 1943 is ridiculous. And they were combined with synchronized nose guns and mandated cannon due to cg issues. The Germans and Russians did have better success with centerline cannon because their guns had a much better ROF.



I looked it up, since you’re so stuck on this one point and did not address anything else. The unsynchronized MG17 rate of fire is 1100rpm. Synchronized is 1000rpm. Significant drop? Hardly.

I guess you’re not counting the FW190A series or Bf109E, are you?

Your original argument was that the P-39 nose mounted armament was insufficient. I think both the Soviet success with the type as well as general principles which I illustrated above, say otherwise.


----------



## P-39 Expert (Apr 18, 2020)

varsity07840 said:


> Climb rate aside, what was the max speed of the P-39N vs. the P-47D, P-51B/D/K, P-38J/L at the altitudes required for bomber escort? What was the P-39N's radius of action after getting to escort altitude? With regard to weight savings on earlier models, given the P-39's poor air to air armament, one would think that removal of the 37mm gun the archaic sychronised .50s and the would be the first step. But that wasn't possible because the aircraft was designed around nose armament particularly the cannon. Removal would affect the cg, just the way expended ammo did. Removal of the nose guns on the P-40 caused no such problems. So, what you would end up with is two slow firing .50 cal guns and a cannon that was totally unsuited for fighter vs fighter combat. Yes, the Russians made good use of the P-39 in that configuration, but I doubt if you could have found an American pilot of that era who would prefer to fight with that type of armament.


Max speed of the P-39N at 25000' was 370-375mph depending on the test. Competitive with the 109G and 190A but certainly well below the two stage P-38, P-47 and P-51.
Radius of action at 25000' was about like a Thunderbolt when each plane had the 110gal drop tanks available in the ETO at that time, on the order of 350-400 miles at about the same speed 280mph TAS. Please remember that the P-39N had completed its production run before the P-47 got into combat in May '43.

Regarding armament, the 37mm cannon wasn't nearly as bad as most people think. Trajectory drop was within 21" of the twin .50s at 400 yards and that was about the outside limit for air-to-air. There were separate buttons on the stick for the .50s and the cannon so you could use just the cannon beyond 400 yards. Rate of fire at 2.5 rounds per second wasn't bad considering the destructive power. One hit was enough to bring down most anything with two engines or less. Reliability was spotty until the L model in mid '42 introduced the little exit vents just aft of the reduction gear. These exhausted the warm cockpit air that was ducted up from the rudder pedal wells onto the breeches of the cannon and twin .50s. This kept the guns from freezing at altitude which was the main cause of jams/interruptions.

According to what I have read AAFpilots were pretty evenly split between preference for the 37mm and 20mm. Biggest problem with the 20mm was only 60 rounds in the drum which was about 6 seconds of firing time. Spitfires held 120 rounds per gun and an increased magazine for the American 20mm would have been the ideal solution but that was not to be.

The Russian solution was to delete the useless .30 caliber wing guns and the IFF radio using the weight savings to further improve performance. They maintained that the 37mm cannon was much more reliable than the 20mm cannon. They also reportedly used the twin .50s against fighters and the 37mm cannon against bombers. Four of the top five Russian aces and scores of 20+ victory aces flew the P-39 and were enthusiastic proponents.

Reactions: Agree Agree:
1 | Like List reactions


----------



## eagledad (Apr 18, 2020)

Venturi

While the ROF of the MG 17 did not suffer too much from synchronisation, it appears the Brownings did. According to Anthony Williams, 

"It is however difficult to find many actual examples of the effects of synchronisation on rate of fire. The Soviet 12.7 mm UBS was stated to fire at 800 rpm instead of 1,050; a reduction of 24%. It also appears that the ShKAS was slowed from 1,800 to 1,300 – 1,500 rpm (17 – 28%) depending on the installation, and the ShVAK from 800 to 700 (12.5%). Some installations appeared to be even worse than this; tests of cowling-mounted .50 M2 in US aircraft revealed RoFs of 400–450 rpm, and anecdotal reports of the Japanese 12.7 mm Ho-103 (which shared the M2's Browning short-recoil 7 mechanism) indicate a similar problem."

Williams gives a normal ROF for the ,50 Browning M2 at 13 rounds per second. (780 rpm).

FYI

Eagledad

Source: http://quarryhs.co.uk/Synchro.pdf

Reactions: Informative Informative:
1 | Like List reactions


----------



## varsity07840 (Apr 18, 2020)

Venturi said:


> I looked it up, since you’re so stuck on this one point and did not address anything else. The unsynchronized MG17 rate of fire is 1100rpm. Synchronized is 1000rpm. Significant drop? Hardly.
> 
> I guess you’re not counting the FW190A series or Bf109E, are you?
> 
> Your original argument was that the P-39 nose mounted armament was insufficient. I think both the Soviet success with the type as well as general principles which I illustrated above, say otherwise.



In the cases of the FW190A and Bf109E neither design was able to accommodate increased/improved wing armament to replace the MG FF cannon in subsequent models. I acknowledged that the Soviets had success with the P-39, but apparently the AAF was of a different mindset since the P-39 was the last nose gun fighter to see combat. One has to wonder why Bell pursued the same design in the P-63.


----------



## drgondog (Apr 18, 2020)

varsity07840 said:


> In the cases of the FW190A and Bf109E neither design was able to accommodate increased/improved wing armament to replace the MG FF cannon in subsequent models.
> 
> *????? the 109K-6 with Mk 108 was a 'pretty good improvement' and so was the MG 131/20 underwing. As for the Fw 190, the MG FF was replaced by MG 131/20 or Mk 108 internal to the wing.*
> I acknowledged that the Soviets had success with the P-39, but apparently the AAF was of a different mindset since the P-39 was the last nose gun fighter to see combat. One has to wonder why Bell pursued the same design in the P-63.[/QUOTE
> ...


----------



## Shortround6 (Apr 18, 2020)

varsity07840 said:


> One has to wonder why Bell pursued the same design in the P-63.



Because work started on what would become the P-63 in Feb 1941. They changed the airfoil (tried for laminar flow), lengthened the fuselage to accommodate different engine or engine with 2 stage supercharger, They moved the wing and got rid of the CG problem/s or at least the worst of them.

Somewhere in there is the P-39E and P-76  This is all started before the P-39 actually sees combat or even regular squadron service (not counting the YP-39s) 

For some reason both Bell and the AAF were enamoured with the 37mm cannon and while the P-39 may have been the last US fighter with nose armament (need better definition of that) to see combat in US service (Russian P-63s?) there were a number of projects that used the 37mm cannon, sometimes in multiples. XP-54 and XP-67 come to mind offhand.


----------



## varsity07840 (Apr 18, 2020)

Shortround6 said:


> Because work started on what would become the P-63 in Feb 1941. They changed the airfoil (tried for laminar flow), lengthened the fuselage to accommodate different engine or engine with 2 stage supercharger, They moved the wing and got rid of the CG problem/s or at least the worst of them.
> 
> Somewhere in there is the P-39E and P-76  This is all started before the P-39 actually sees combat or even regular squadron service (not counting the YP-39s)
> 
> For some reason both Bell and the AAF were enamoured with the 37mm cannon and while the P-39 may have been the last US fighter with nose armament (need better definition of that) to see combat in US service (Russian P-63s?) there were a number of projects that used the 37mm cannon, sometimes in multiples. XP-54 and XP-67 come to mind offhand.



Last single engine fighter with synchronized nose guns.


----------



## varsity07840 (Apr 18, 2020)

the Bf109K-6 had a new wing which is what I'd call a major redesign as I noted earlier. In the 190, excluding the MG 151 wing root guns, there was never a variant that carried more than one internally mounted wing gun. In most cases the outboard cannon primarily the MG FF was deleted. As far as podded underwing guns, I don't consider them to be wing guns, as for the P-39 and P-63. They were underwing because they wouldn't fit in the wing.

Reactions: Informative Informative:
1 | Like List reactions


----------



## drgondog (Apr 18, 2020)

varsity07840 said:


> the Bf109K-6 had a new wing which is what I'd call a major redesign as I noted earlier. In the 190, excluding the MG 151 wing root guns, there was never a variant that carried more than one internally mounted wing gun. In most cases the outboard cannon primarily the MG FF was deleted. As far as podded underwing guns, I don't consider them to be wing guns, as as for the P-39 and P-63. They were underwing because they wouldn't fit in the wing.



Bf 109K may have had a new wing but was named and identified as 'Bf 109'. As to the Fw 190?
Fw 190A5/U9&10 4xMG151/20 in wings
Fw 190A-5/U10 2xMG151/20 plus 2xMk 108 (outboard) wings
Fw 190A-6 4xMG151/20; Fw 190A-6/R2 2xMG151/20 plus 2xMk 108
Fw 190A-7 4xMG 151/20 wings 2xMG131 cowl

Fw 190D-10 2xMG 151/20 plus 2xMk 108 

Fw 190A-8/R1 2xMG131 cowl, 6x MG151 wings -
To name most of the variants that had the much more powerful MG 151/20 and Mk 108 in the wings.


----------



## varsity07840 (Apr 18, 2020)

drgondog said:


> Bf 109K may have had a new wing but was named and identified as 'Bf 109'. As to the Fw 190?
> Fw 190A5/U9&10 4xMG151/20 in wings
> Fw 190A-5/U10 2xMG151/20 plus 2xMk 108 (outboard) wings
> Fw 190A-6 4xMG151/20; Fw 190A-6/R2 2xMG151/20 plus 2xMk 108
> ...



You're digging too deep into '109 minutiae. The P-51 didn't need a new wing to accommodate an all .50 cal battery, four then six guns. The two nose guns P-36A evolved into the two wing gun P-36C and P-40 to the six guns P-40E without a new wing. The F4U evolved from a 2 wing gun prototype to a six .50 cal or four 20mm battery with the same wing. They all retained the same designation. The FW 190A8/R1 had four of its guns UNDER the wings not in them. Why was that?. The rest of the 190s you list had two of the guns (synchronized) in the WING ROOTS not in the WINGS. The original wing gun in the 190 was an MG 17. They were never able to increase the NUMBER of guns in the wing. Change in caliber was the best they could do. The P-39 wing could not accommodate a modern gun battery in the wings, hence the under wing guns as per the 109 and 190. The drag induced by the underwing guns on the 109 and 190 made them easy meat for Allied fighters. As far as the P-39Q goes, it didn't really matter. It was already a dog before the Q was introduced. Even the Soviets realized that and removed the gun tubs. Even Bell caught on and produced a batch of Qs without them.

Reactions: Agree Agree:
1 | Like List reactions


----------



## tomo pauk (Apr 18, 2020)

Lo and behold, a Fw 190 with MK 108 in the outer wing: link.

Reactions: Informative Informative:
1 | Like List reactions


----------



## varsity07840 (Apr 18, 2020)

P-39 Expert said:


> Max speed of the P-39N at 25000' was 370-375mph depending on the test. Competitive with the 109G and 190A but certainly well below the two stage P-38, P-47 and P-51.
> Radius of action at 25000' was about like a Thunderbolt when each plane had the 110gal drop tanks available in the ETO at that time, on the order of 350-400 miles at about the same speed 280mph TAS. Please remember that the P-39N had completed its production run before the P-47 got into combat in May '43.
> 
> Regarding armament, the 37mm cannon wasn't nearly as bad as most people think. Trajectory drop was within 21" of the twin .50s at 400 yards and that was about the outside limit for air-to-air. There were separate buttons on the stick for the .50s and the cannon so you could use just the cannon beyond 400 yards. Rate of fire at 2.5 rounds per second wasn't bad considering the destructive power. One hit was enough to bring down most anything with two engines or less. Reliability was spotty until the L model in mid '42 introduced the little exit vents just aft of the reduction gear. These exhausted the warm cockpit air that was ducted up from the rudder pedal wells onto the breeches of the cannon and twin .50s. This kept the guns from freezing at altitude which was the main cause of jams/interruptions.
> ...


 So, we're in agreement that the Russians used the P-39 effectively in a low altitude environment. What hasn't been discussed is the victory to losses ratio for them against German fighters. I don't pretend to know what it was, but the number of kills achieved by German aces that were of the same or higher caliber than their Russian ace counterparts might give us an indication. Certainly their scores were much higher. In North Africa, German pilots were quoted as saying they shot down P-39s like flies.


----------



## XBe02Drvr (Apr 19, 2020)

varsity07840 said:


> So, we're in agreement that the Russians used the P-39 effectively in a low altitude environment. What hasn't been discussed is the victory to losses ratio for them against German fighters. I don't pretend to know what it was, but the number of kills achieved by German aces that were of the same or higher caliber than their Russian ace counterparts might give us an indication. Certainly their scores were much higher. In North Africa, German pilots were quoted as saying they shot down P-39s like flies.


Do reliable, credible statistics even exist for specific types fighter vs fighter kill ratios? Since varying percentages of kills on both sides were non-fighter aircraft, raw kill score comparisons are hardly valid. Also, many of the Experten laid the groundwork for their impressive scores early on against poorly trained Soviets in obsolete aircraft, while VVS pilots who survived to run up their scores mostly date from later times when higher performance Soviet fighters became available. Apples to apples? Hardly.
Cheers,
Wes

Reactions: Agree Agree:
2 | Like List reactions


----------



## Kevin J (Apr 19, 2020)

XBe02Drvr said:


> Do reliable, credible statistics even exist for specific types fighter vs fighter kill ratios? Since varying percentages of kills on both sides were non-fighter aircraft, raw kill score comparisons are hardly valid. Also, many of the Experten laid the groundwork for their impressive scores early on against poorly trained Soviets in obsolete aircraft, while VVS pilots who survived to run up their scores mostly date from later times when higher performance Soviet fighters became available. Apples to apples? Hardly.
> Cheers,
> Wes


The VVS had something called 'group area fighting tactics'. IIRC, 4 pairs of fighters stacked between 8 and 12 thou feet. The bottom pair were the shooters, those gifted enough to be able to hit their target, those above, assigned to protect them. I imagine they lost a lot of novices that way although it would have enabled their 2 shooters to rack up quite big scores.


----------



## drgondog (Apr 19, 2020)

varsity07840 said:


> You're digging too deep into '109 minutiae. The P-51 didn't need a new wing to accommodate an all .50 cal battery, four then six guns. The two nose guns P-36A evolved into the two wing gun P-36C and P-40 to the six guns P-40E without a new wing. The F4U evolved from a 2 wing gun prototype to a six .50 cal or four 20mm battery with the same wing. They all retained the same designation. The FW 190A8/R1 had four of its guns UNDER the wings not in them. Why was that?. The rest of the 190s you list had two of the guns (synchronized) in the WING ROOTS not in the WINGS.
> 
> *In what universe is an inboard wing gun requiring synchronization Not part of the WING?? The Fw 190A8/R1 did have 1x20 in the wing and two 2x20pods under - so what? what about the other half dozen variants I mentioned - all with either 20mm and/or 30 mm two gun batteries internal to the wing.*
> 
> ...



Not digging 'too deep'. You made a bold (and incorrect) statement that Bf 109 and Fw 190A didn't expand inner wing 20mm beyond the 1xFF for each wing. Simply wrong - own up to it rather than flail around comparing design changes from G to K as dismissive of the airframe designator.

For example - the Mustang airframe went from 2x30cal plus 1x50 cal in each wing and two (synchronized) in the cowl - then to 2x20mm in each wing, then the 2x50 cal in each wing plus two 50cal (Synchronized) in the cowl Plus dive brakes Plus external pylons with removable racks for bombs and fuel plus internal pluming for fuel transfer - then removed the dive brakes but retained the additional wing structural improvements required for dive bombing - to 2x50 cal with Completely new engine and further beef up for increased deflection of ailerons - to 3x50cal in each wing. That said, ALL of the Mustangs from P-51-1-NA through A-36 through P-51A/B/C/D/K were capable of easy mod to install 2x20mm in each wing as well as the intended P-51F in interceptor role (never ordered but design performed).

So why, in your mind,do you consider that the 109K should have a different designation from generic 109? Wing modifications? Lol.

Reactions: Like Like:
1 | Like List reactions


----------



## varsity07840 (Apr 19, 2020)

drgondog said:


> Not digging 'too deep'. You made a bold (and incorrect) statement that Bf 109 and Fw 190A didn't expand inner wing 20mm beyond the 1xFF for each wing. Simply wrong - own up to it rather than flail around comparing design changes from G to K as dismissive of the airframe designator.
> 
> For example - the Mustang airframe went from 2x30cal plus 1x50 cal in each wing and two (synchronized) in the cowl - then to 2x20mm in each wing, then the 2x50 cal in each wing plus two 50cal (Synchronized) in the cowl Plus dive brakes Plus external pylons with removable racks for bombs and fuel plus internal pluming for fuel transfer - then removed the dive brakes but retained the additional wing structural improvements required for dive bombing - to 2x50 cal with Completely new engine and further beef up for increased deflection of ailerons - to 3x50cal in each wing. That said, ALL of the Mustangs from P-51-1-NA through A-36 through P-51A/B/C/D/K were capable of easy mod to install 2x20mm in each wing as well as the intended P-51F in interceptor role (never ordered but design performed).
> 
> So why, in your mind,do you consider that the 109K should have a different designation from generic 109? Wing modifications? Lol.



I said that with the 109 and 190, they were never able to expand beyond one gun in the wing. The wing itself not the wing root and not under the wing. Is that true or not? As for the P-51, you've made my point. The wing was adaptable to different gun batteries. It didn't need add on gun tubs for increased fire power. Same with the P-40 and F4U. That was not the case with the 190 and 109.


----------



## Reluctant Poster (Apr 19, 2020)

Shortround6 said:


> Greg, please go over the time line for the P-38. There are two different issues with fuel at different times.
> 
> The early US fuel had little or no aromatics, this was in 1940 or so, If you want 100/125 or 100/130 you have to use aromatics. At least if you want to make fuel on a large scale.
> 
> ...



As Shortround notes the US started producing and using avgas with high aromatic content in 1942, however his chronology is slightly askew:
4 cc of tetraethly lead was allowed in November 1941 (Others sources say December)
125 PN was called for in May 1942. (Other sources note that it was mandated after July 1)
130 PN was required in December 1942.
This from AAF Historical Study No 65 "Aviation Gasoline Production and Control" which I believe I have posted previously but I am attaching here.

The US began introducing aromatics into their fuels produced in the l USA in May 1942 with the production of the aromatic cumene (Isopropyl benzol). In addition all 14 of the catalytic crackers existing in the US were converted to the production of Avgas.
To quote Sam Heron from his book Development of Aviation Fuels
“In lieu of suitable straight run gasolines, aromatics and the sensitive cat cracked gasolines (which largely owed their sensitive and rich mixture properties to aromatics) became desirable material for making Grade 100/130 in maximum quantity.”

An excellent book for those who are interested in the actual production of Avgas (and every thing else related to petroleum):
Amazon product

I purchased this book about 5 years ago but it has since been digitized and is available via Google Books for free.
A History of the Petroleum Administration for War, 1941-1945
This book says the following about cumene and its importance:
















The above figure from the same book illustrates the importance of the aromatic cumene and cat cracking in enabling the production of massive quantities of high octane avgas.

Reactions: Bacon Bacon:
1 | Informative Informative:
3 | Like List reactions


----------



## ssnider (Apr 19, 2020)

Are you seriously saying that German engineers could not design a wing for the FW 190 to add more guns if they wanted to? The pod packs of 2-2o mm guns were field kits that could be quickly added or removed as needed. The Germans saw merit in the Russian view that wing guns were MUCH less effective than centerline guns. The British and Americans seem to have valued cowl streamlining more and added guns to the wings instead. Its a matter of design priorities and preferences.


----------



## drgondog (Apr 19, 2020)

varsity07840 said:


> I said that with the 109 and 190, they were never able to expand beyond one gun in the wing. The wing itself not the wing root and not under the wing. Is that true or not? As for the P-51, you've made my point. The wing was adaptable to different gun batteries. It didn't need add on gun tubs for increased fire power. Same with the P-40 and F4U. That was not the case with the 190 and 109.



Varsity - you REALLY need to pick up some good books about Fw 190 - there are tons of Internal (to the wing as defined below) four gun 20 and 20/30mm combinations from variances of the A-5 all the way through Fw 190D. The Fw 190 A-7 and A-8 variants had more internal firepower on board than any primary Allied fighter with 2xMG131, 4xMG151 - all under the skin - before adding pods- and before swapping a Mk 108 for MG 151/20mm. 

What they sacrificed was range when compared to say a P-51-1-NA with 90 gal fuel cell in each wing.

You seem hung up on the definition of wing root versus wing. The Root Chord, wing root (as defined by the fuselage-wing interface) and the wing all the way out to the tip. Anything from the wing tip to the wing root chord is part of the wing. Any gun mouted internally between the upper airfoil surface and the lower airfoil surface is internal to the wing.

Reactions: Like Like:
3 | Like List reactions


----------



## varsity07840 (Apr 19, 2020)

ssnider said:


> Are you seriously saying that German engineers could not design a wing for the FW 190 to add more guns if they wanted to? The pod packs of 2-2o mm guns were field kits that could be quickly added or removed as needed. The Germans saw merit in the Russian view that wing guns were MUCH less effective than centerline guns. The British and Americans seem to have valued cowl streamlining more and added guns to the wings instead. Its a matter of design priorities and preferences.



I'm sure they could. But, and I'm speculating here, perhaps there was concern about interrupting production. That was the case with the P-38K which though vastly superior to the J, would have halted production for retooling for revised cowlings. There were some Germans who did not agree with the Russian approach, notably Adolf Galland who thought the centerline guns on the Bf-109F was a step backwards.


----------



## Shortround6 (Apr 19, 2020)

This argument goes round and round. What we have for "evidence" is a few quotes from different aces. Not to be disregarded but they are their opinions. Unless back up by facts or firing tests we do have room for _reasonable_ doubt. 

We also need to acknowledge the intended target. Shooting at an He 111 is rather different than shooting at a 109. 

We also get stories about how big the groups were from wing mounted guns fired on the ground, way bigger than any gun would have passed a test at the factory so the problem is not the gun or the ammo. However you have more than the wing left, you have the mounting system to wing that allows for the gun/s to aimed in slightly different directions so you can get all guns to hit in spot if you want. Some mounts allowed for slight movement against springs to dampen recoil.
And we are to believe that the wing which can keep from breaking while pulling a high speed 5-6 G turn on a 3-6 ton fighter somehow flops around like a wet noodle under the recoil of the guns? Or one wing bend one way and the other wing bends the other way when turning? 

We have diagrams for British guns with dispersion that is truly huge. An order of magnitude worse than any inspector would pass either ammo or gun for at the factory. I have no explanation except deliberate policy in setting up the gun mounts?

Reactions: Agree Agree:
2 | Like List reactions


----------



## Reluctant Poster (Apr 19, 2020)

varsity07840 said:


> I'm sure they could. But, and I'm speculating here, perhaps there was concern about interrupting production. That was the case with the P-38K which though vastly superior to the J, would have halted production for retooling for revised cowlings. There were some Germans who did not agree with the Russian approach, notably Adolf Galland who thought the centerline guns on the Bf-109F was a step backwards.


The K was not vastly superior to the J. Unless you have some new data that supports this.


----------



## varsity07840 (Apr 19, 2020)

Reluctant Poster said:


> The K was not vastly superior to the J. Unless you have some new data that supports this.


My understanding is that at the same altitude, the K was 40mph faster than the current production J. The service ceiling exceeded 45,000 feet and the full loaded climb rate in military power was 4,800 FPM. That information comes from Warren Bodie. I'd say that's a vast improvement.


----------



## drgondog (Apr 19, 2020)

varsity07840 said:


> I'm sure they could. But, and I'm speculating here, perhaps there was concern about interrupting production. That was the case with the P-38K which though vastly superior to the J, would have halted production for retooling for revised cowlings. There were some Germans who did not agree with the Russian approach, notably Adolf Galland who thought the centerline guns on the Bf-109F was a step backwards.



Galland objected most to losing the 2xFF 20's in the wing- IIRC he had especially modified F to accept the twoxFF plus the CL 20mm.

The K never flew in ops and the only version was a J modified with larger prop and gear ratio change - that said the only comparison test flown between the K and J was stacked from the beginning when the K Gross Weight at Take Off was 600 pounds lighter than the 'competing J' - the difference in climb was about what you would expect. Additionally, when that test flight was made, P-51B and C production was in full stride and the P-51D was in serial production. There simply wasn't enough difference to slow down J/L production to even think about the K.

Reactions: Informative Informative:
2 | Like List reactions


----------



## varsity07840 (Apr 19, 2020)

drgondog said:


> Galland objected most to losing the 2xFF 20's in the wing- IIRC he had especially modified F to accept the twoxFF plus the CL 20mm.
> 
> The K never flew in ops and the only version was a J modified with larger prop and gear ratio change - that said the only comparison test flown between the K and J was stacked from the beginning when the K Gross Weight at Take Off was 600 pounds lighter than the 'competing J' - the difference in climb was about what you would expect. Additionally, when that test flight was made, P-51B and C production was in full stride and the P-51D was in serial production. There simply wasn't enough difference to slow down J/L production to even think about the K.



I realize the K was not operational. I don't think it was ever contemplated that P-51 production should be halted, even though Bodie says the K tested a Eglin showed superior performance to the P-51 and P-47. The extant of the performance advantages of the K is probably a moot point considering it was still powered by an Allison that didn't like Northern Europe, had compressibility issues and a cockpit that was a nightmare for an inexperienced pilot.


----------



## Reluctant Poster (Apr 19, 2020)

varsity07840 said:


> I realize the K was not operational. I don't think it was ever contemplated that P-51 production should be halted, even though Bodie says the K tested a Eglin showed superior performance to the P-51 and P-47. The extant of the performance advantages of the K is probably a moot point considering it was still powered by an Allison that didn't like Northern Europe, had compressibility issues and a cockpit that was a nightmare for an inexperienced pilot.


The tests were by Lockheed not by the airforce.


----------



## varsity07840 (Apr 19, 2020)

Reluctant Poster said:


> The tests were by Lockheed not by the airforce.



According to Bodie, the tests at Eglin were conducted by AAF.


----------



## Reluctant Poster (Apr 19, 2020)

varsity07840 said:


> According to Bodie, the tests at Eglin were conducted by AAF.


Bodie makes a lot of unsubstantiated claims in his book. According to this report the tests were by Lockheed.
http://www.wwiiaircraftperformance.org/p-38/P-38J_performance_11march44.pdf

Reactions: Informative Informative:
1 | Like List reactions


----------



## Reluctant Poster (Apr 19, 2020)

drgondog said:


> Varsity - you REALLY need to pick up some good books about Fw 190 - there are tons of Internal (to the wing as defined below) four gun 20 and 20/30mm combinations from variances of the A-5 all the way through Fw 190D. The Fw 190 A-7 and A-8 variants had more internal firepower on board than any primary Allied fighter with 2xMG131, 4xMG151 - all under the skin - before adding pods- and before swapping a Mk 108 for MG 151/20mm.
> 
> What they sacrificed was range when compared to say a P-51-1-NA with 90 gal fuel cell in each wing.
> 
> You seem hung up on the definition of wing root versus wing. The Root Chord, wing root (as defined by the fuselage-wing interface) and the wing all the way out to the tip. Anything from the wing tip to the wing root chord is part of the wing. Any gun mouted internally between the upper airfoil surface and the lower airfoil surface is internal to the wing.


Here is an excellent illustration of some of the permutations of FW 190 armament 
https://forums.eagle.ru/attachment.php?attachmentid=111393&d=1421221687

Reactions: Like Like:
1 | Informative Informative:
1 | Like List reactions


----------



## fubar57 (Apr 19, 2020)

Thank you for that


----------



## drgondog (Apr 19, 2020)

varsity07840 said:


> I realize the K was not operational. I don't think it was ever contemplated that P-51 production should be halted, even though Bodie says the K tested a Eglin showed superior performance to the P-51 and P-47. The extant of the performance advantages of the K is probably a moot point considering it was still powered by an Allison that didn't like Northern Europe, had compressibility issues and a cockpit that was a nightmare for an inexperienced pilot.



Bodie was very much in love with the P-38. First the P-38K had a rate of climb from SL to 25000 feet that was greater than a combat loaded P-51B-1 or -5. That said, the flight tests of the P-51B-5-NA at 8500 pounds (versus 9100 fully loaded internally before the 85 gal tank was installed) was between 4300 fpm @6500 feet at 67" and 4600fpm @3500ft and 75" - With draggy wing racks and over 2000 fpm at 30K - which was more than K or J.

Reactions: Informative Informative:
2 | Like List reactions


----------



## varsity07840 (Apr 20, 2020)

Reluctant Poster said:


> Biode makes a lot of unsubstantiated claims in his book. According to this report the tests were by Lockheed.
> http://www.wwiiaircraftperformance.org/p-38/P-38J_performance_11march44.pdf


Pretty convincing.


----------



## Reluctant Poster (Apr 22, 2020)

Reluctant Poster said:


> Here is an excellent illustration of some of the permutations of FW 190 armament
> https://forums.eagle.ru/attachment.php?attachmentid=111393&d=1421221687









FW-190 A-6

Reactions: Like Like:
2 | Informative Informative:
2 | Like List reactions


----------



## Reluctant Poster (Apr 22, 2020)

Reluctant Poster said:


> View attachment 578409
> 
> 
> FW-190 A-6


Another one from
File:Fw 190 weapons arrangement.jpg - Wikimedia Commons 





Note the Oerlikons in the outer positions

Reactions: Like Like:
1 | Informative Informative:
1 | Like List reactions


----------



## Reluctant Poster (Apr 22, 2020)

Shortround alluded to the variety of blends that constituted 130 fuel. The attached paper clearly shows the immense number of base stocks used to produce 130 and the different proportions of various blending agents required to meet the 130 rating. Note that cumene, toluene and xylene are all aromatics.
The F-3 test was for lean mixture, while the F-4 test was for rich mixture.
I was confused at first but realized that a rich mixture rating of S+1.25 is the same as a PN of 130.

Reactions: Informative Informative:
1 | Like List reactions


----------



## jmcalli2 (Apr 23, 2020)

Shortround6 said:


> The P-39N used a different radiator duct set-up, it used a different oil cooler, it had no intercooler and it no turbo hanging out the bottom. Plus the lower canopy and few other minor tweaks? The XP-39 had a much larger drag coefficient.
> Claiming that the P-39N could do nearly 400mph with about the same amount of power as the XP-39 had so the Xp-39 should be almost as fast disregards these large differences in drag between the two airplanes.
> The claim of 390mph in the time before Langley also disregards the chronic cooling problems the XP-39 had, both engine coolant and oil coolant.
> The claim of 390mph in the time before Langley also disregards the documented problems with drive shaft that lead to a restriction on maximum RPM.
> ...



http://www.wwiiaircraftperformance.org/P-39/P-39N_level-speeds.jpg


----------



## GregP (Apr 23, 2020)

Regarding post #81, Shortround, I mainly agree with your data except for the timeline.

I have seen original Allison correspondence regarding the aromatics via a friend who overhauls Allisons, and they fixed the jetting rapidly after they got some 20% aromatic fuel delivered to the factory. Before that, the issue could not be duplicated on the test stand, and they were scratching their heads because the engines were running fine in test. I regret to say I don’t recall the date of the document because, at the time (some 8 years ago), it wasn’t of any import to me as I was just trying to establish the facts.

The issue with lead separation in the intercooler did not happen exactly coincident with the aromatics and is a separate issue from the ethyl aromatics added to the fuel. It was about the increase in lead. Yes, it took some time to address, even partially.

I call it “British fuel” because the 8th Air Force P-38 fuel tanks were filled with fuel on airfields in Britain. I really have no idea of the source for the bowser trucks that fueled the P-38s and I hazard a guess you likely don’t either. Could be U.S. supplied, could be supplied by Britain. But they didn’t fill them up in the U.S.A. and then magically transport the P-38s to Britain. And the freighter convoys did bring fuel, to be sure, but they were mostly trying to stop Britain from starving. I imagine Britain supplied a lot of fuel to the early U.S. aircraft based there while we supplied a lot of food and other war material, at least early on. Regardless of the source, the P-38s were fueled with different fuel than the engines were run-in with back in Indiana at Allison, causing one major problem for the early P-38 squadrons until somebody thought to send a fuel sample to Allison consistent with the fuel actually being run in the field. When they DID send some and it was tried on the test stand, the issue showed up immediately. It is WAY easier to troubleshoot a problem when you can duplicate it in a running test engine than when you can’t. You can’t imagine they’d investigate a problem if the problem had not been reported, and there were some months where Allison simply could not replicate the engine failure problems because they were running fuel supplied locally and it ran fine on the test stand.

The date when U.S. fuel first had the aromatics bumped from 2% to a lot more is not the date when that reformulated new fuel started flying in combat. It is also not the date when someone thought to send some of it to Allison Engines in Indiana.

When they made new airplanes, they didn’t show up in Europe right away. It took some time for them get built and accepted, get to training bases for pilots & mechanics, get some pilots & mechanics trained, and then prep the aircraft and personnel for transport and, finally, get all to Europe. When they got there, they weren’t in combat immediately. They still had to work up to operational ready status on the new type.

Likewise, when they made new fuel, they didn’t send it immediately to combat with the P-38 units. They’d first have to make it, run a preliminary test, transport it to a test unit, test it in service with the test unit, and then issue some to stateside units flying the P-38. If it performed well there (not always a given), then it could likely commence the process of being sent overseas, if enough was available for that at the time. I doubt very seriously that the fuel was allocated to P-38s in Britain as a first step in the distribution process. They were flying a LOT more P-38s elsewhere in North Africa, Alaska, the South Pacific, and in Conus units than they were in the UK at the time. When has the military EVER made the correct decision to deploy something to just the right place at just the right time? I’d say close to never. The closest I can think of prior to 1960 is when we got surprised in Korea by the MiG-15 and sent over some F-86’s to Japan pretty quickly to be competitive. Prior to that, the military wasn’t known for cutting-edge thinking and action in the logistics / deployment chains. It was much more of a case of “it’ll eventually get there.”

I’ve been posting about Allison engine and general P-38 issues for more than 10 years and have covered much of it many times in the past to little or no comment except for some nitpicking about details. In fairness, some of the nitpicking was correct, but usually ignored 95% of the post data. I could stand to review the P-38 timeline with the 8th Air Force if I want to talk about that subject other than from memory. But early use of the P‑38 in the ETO did see fuel-related issues, the early Allisons sent there did have manifold / intercooler issues that included both mixture problems and lead-separation, and they did have issues with freezing boost regulators and poor cockpit heaters. It took some time to get the factory informed of the issues, replicate them in test, come up with a fix, get them tested, get them into production, and then get them to the front lines. Nothing was overnight unless it was sitting on a counter waiting to be used. Unlikely at best.

The P-38J-25-LO and later models didn’t really HAVE issues to speak of. The P-38J’s were first delivered in fiscal year 1943, around September, which is not too far past when we started flying the P-38 overseas. But I doubt they got many to operational combat units before late 1943 to early 1944, particularly the P-38J-25-LO. It likely didn’t hit actual combat service until mid-1944 or later. About the time the P-38 got “fixed,” Doolittle had them drawn down in the ETO and by sometime in fall 1944, there was only one unit flying PR P-38s in that theater. Early J models were still seeing some fuel issues according to many sources.

The P-38J-25-LO and L engines ran well, the airframes had factory-fitted dive flaps so they could dive after anything without fear of not being able to pull out, they had hydraulic ailerons, they out-turned most of the opposition when flown in the correct part of the envelope, they had electric cockpit heaters, and they were being run on fuel that was anticipated by the engine factory. Were they perfect? No. By that time, there were newer, faster aircraft being flown by the enemy but, if they tangled with a competently-flown late-model P-38, it wasn’t an easy fight by any means, and they flat weren’t going to climb away from a P-38 very often.

None of this detracts from the fact that early P-38s (D, E, F, G, H) were basically not combat-ready as deployed and doesn’t erase the issues that were experienced. I am not glossing over the problems that were seen. I am saying they were corrected in due time, but more time than users of the P-38 and even Lockheed were happy with. The only real timeline for correcting problems that users are satisfied with is immediately.

Lockheed did send Tony Levier over to Europe to show the service pilots that the P-38 wasn’t a hard airplane to fly when flown by a pilot familiar with it. But that was in 1944, later than the early P38 escort period.

Your post #81 has good information in it as most of your posts do. But I am not sure your timeline as stated is exactly the way it went in the war. Might well be the timeline for when fuels were initially formulated, but lab fuel in a test beaker and fuel in the tanks of combat aircraft are two different animals.

Of course, my timeline could be a bit off, too. I confess I pay much more attention to the aircraft themselves than to the war itself, other than collecting data about it from recognized sources. Not saying you are wrong, Shortround, but perhaps your timeline isn’t exactly spot-on, either. The issues I brought up were real according to many sources and the pilots who flew them. The exact timeframes may be plus or minus some months.

Reactions: Like Like:
2 | Like List reactions


----------



## Shortround6 (Apr 23, 2020)

jmcalli2 said:


> http://www.wwiiaircraftperformance.org/P-39/P-39N_level-speeds.jpg




And your point is???????
read what I wrote please, read the link/s to the Langley report. 
and look at pictures.

XP-39 left side. 




Large scoop for intercooler. balanced by a large scoop on the right side for the oil cooler. 




Then you have the turbo and 4 waste gate pipes hanging out the bootom

And you have an incredibly lousy radiator set up in the wing. Outlet can be seen in top photo interrupting the port wing walkway. There was no adjustment for either the intake or the exit to control airflow, turns of the duct inside the wing were sharp and structural members obstructed airflow. 

The tall canopy may have been the least of the aerodynamic problems. 

It doesn't matter what the P-39N did (or any other model of the P-39) if these later versions had 2/3s the drag of the XP-39. In fact it only confirms the XP-39 could not have done what is claimed.

Reactions: Like Like:
2 | Agree Agree:
2 | Disagree Disagree:
1 | Like List reactions


----------



## Shortround6 (Apr 23, 2020)

An old P-39 thread with a lot of pictures from the XP-39s time at Langley.

Bell P-39 Airacobra

edit, sorry guys, I forgot to say go directly to page 6. 

Original coefficient of drag 0.0321

Coefficient of drag of a P-39 0.0217 from America's Hundred Thousand. I don't know where the Author got them.

The NACA spent a lot of time on the XP-39 trying different radiators, oil coolers and intercoolers. See the pictures so kindly provided johnbr.

Reactions: Like Like:
1 | Like List reactions


----------



## Zipper730 (Apr 23, 2020)

Shortround6 said:


> Original coefficient of drag 0.0321


That would be this design...






Okay, so the intercooler is on the right side, the oil cooler is on the left side, with the radiator in the inboard left wing-root, with the airflow exiting out the top side of the wing? What are those small ports/scoops located just below the intercooler/oil-coolers, and the vents located next to the engine do?



> Coefficient of drag of a P-39 0.0217 from America's Hundred Thousand. I don't know where the Author got them.


Which would be the upper image here. It looks like they were trying to refine the cooler scoops, and the covering of the turbocharger. What's the typical coefficient of drag for the P-40D/E, the Spitfire Mk.V, and P-38F come out to?






This figures seems pretty close to the V-1710 with 9.6 supercharger, but not the improved radiators operational aircraft and the top intake. It seemed the primary issue here was the fact that they 9.6 supercharger didn't work.



 GregP
, 

 P-39 Expert


----------



## Reluctant Poster (Apr 24, 2020)

The Bad British Fuel Myth was originated by Warren Bodie in his book “The Lockheed P-38 Lightning”. Since the advent of the internet it has taken on a life of its own with various posters adding embellishments of their own such as “the lead was separating out in the fuel” “the fuel in the UK had a higher aromatic content” and other unsubstantiated statements.

The actual quote from Bodie is: _“Gasoline available in the MTO obviously came from a different source, probably direct from the U.S.A. And it is well known fact that fuel in the United Kingdom was of poor quality. If you remember that the Allisons were not turbocharged in any fighters except the P-38s and that no Merlin had such supercharging, it becomes rather evident that fuel quality could easily have been one of the most important culprits.” 
“It is the authors opinion that British fuels furnished to the eighth Air Force were improperly blended at the time and the tetraethyl lead compound was separating out from the gasoline in the Allison manifold.”_

That’s it, all pure speculation with no footnotes or historical references, nothing to back it up. In fact I have yet to see a shred of evidence indicating the fuel in the UK was of any lesser quality than elsewhere. There is however plenty of evidence to show that there was no significant difference.

It is instructive to note that the definitive book on the Allison “Vees for Victory” by Daniel Whitney does NOT mention Bad British Fuel anywhere in its text.

A good discussion of Britain’s avgas supplies is presented in “Britain War Machine” by David Edgerton. There is a chapter that discusses Britain's sources of supply in some detail. As he notes “_By the middle of the war nearly all of the aviation spirit, indeed nearly all the petroleum products, were to come from the USA”_

Another good source is the Army Air Forces Historical Studies No 65 “Aviation Gasoline Production and Control which states:
_“In addition, the British were asked to alter their fuel specifications to meet those of the U.S. Air Corps and Navy.”_ (Dec 1941)

But let’s ignore that, in the spirit of the underlying theme that the British were incompetent buffoons that couldn't do anything right, and assume their gasoline was inferior. That brings up the question of how much British fuel was there. The answer is: not much.

More than 85% of all high octane (or PN if you prefer) gasoline produced by the Western Allies (ie not including the USSR) was produced in the continental USA.
Before World War II the British had no oil industry to speak of. In 1938 (the last full year before the war) the only source of oil indigenous to the UK was Scottish shale oil, of which a total of 128,000 tons was produced. This represented 1.3% of the UK’s total needs. In other words more than 98% of her oil was imported, making her the world’s largest importer of oil by far. It should be noted that all shale oil was refined at the small refinery dedicated to the shale oil industry at Pumpherston in Scotland. This refinery did NOT produce avgas.

In 1939 Britain’s first commercially viable oil field was discovered in Duke’s Woods. Efforts were made during the war to develop these fields developed such that the total amount of UK oil produced had doubled by 1943, however demand had increased as well so UK contributions were still a drop in the bucket. Initially this crude oil was refined at Pumpherston, but later it was sent to the small Ellesmere Port lube oil refinery. Note that this refinery was also not equipped to produce avgas. In other words no avgas was produced using indigenous UK oil.
“The Production and Refining of Indigenous Oil in Britain” by B S Hoyle describes the history of the British oil industry prior to the discovery of North Sea oil. To get an idea of how insignificant UK production was, interesting to note that the UK oil fields produced about 3.5 million barrels of crude for the entire war which pales into insignificance when you realize the US was producing 3.8 million barrels A DAY in 1941.

Furthermore; in 1938 Britain was importing the majority of its oil as finished product. Half of the imports were in the form of what the British term motor spirit and aviation spirit (gasoline), a quarter in other refined products such a kerosene, diesel and fuel oil, with about a quarter arriving as crude oil.
There were only a 13 refineries in the UK ( vs ~400 in the US), 7 very small ones specializing in products such as bitumen (asphalt) and lube oils, the previously noted plant at Pumpherston and 5 larger ones (still small by US standards) relying on imported crude oil from Venezuela, the US and the Middle East. It is interesting to note that after the entry of the US into the war Britain actually shut down more than half of its refining capacity. Refinery throughput sank from 2,400,000 tons in 1938 to 908,000 tons in 1943!
Britain realized the importance of high octane avgas (PN of 100 or more) and placed a high priority on it. Since the British had no supplies of their and felt they could not rely on the neutrality leaning United States to sell them oil in a future war, they set up contracts with refineries in Aruba (Standard Oil of New Jersey), Curacao (Shell) and Trinidad using Venezuelan (and some Trinidad) oil. In addition the Anglo Persian Oil company (now BP) upgraded their large refinery in Abadan (Iran) and Shell added avgas capacity to their refineries in the Dutch East Indies.

Only one of the refineries in the UK was upgraded to produce 100 octane fuel (Stanlow). In addition 2 hydrogenation plants were built in the UK. The plant at Billingham used the same Bergius process used by the majority of German synthetic oil plants with one important difference; by the beginning of World War II it had switched from coal to creosote as its feedstock. The plant at Heysham hydrogenated gas oil (gas oil is the heavier faction produced by basic refining) that had been produced at the refinery in Trinidad. A planned third plant was canceled in favor of more US oil with the equipment shipped to Trinidad instead. Stanlow also used gas oil from Trinidad as its base stock.

After the US entry into the war there was a rationalization of the transportation of oil supplies to reduce the pressure on the limited number of oil tankers, many of which (approximately 10% of the fleet) had been quickly lost because of the US Navy's refusal to adopt the convoy system on the US east coast.

From “Aviation Gasoline Production and Control”:
_“For the sake of efficiency in distributing the insufficient supply, it was decided to allocate to the AAF the output of the Curacao and Trinidad refineries. This production was considered as a unit with the US Gulf Coat plants so as to relieve tankers for the Atlantic and Pacific ocean transportation. Thus arrangements were made to supply the AAF at Ponce in Puerto Rico and Jamaica from Curacao.”_

The Japanese graciously took the output of the Far East refineries, while much of Abadan's went to the USSR with the rest used in the Middle East and the CBI theater.

The 5 refineries producing avgas in the north east (Philadelphia, Linden NJ and Baltimore) were the closest supply to the UK but lost their source of crude oil from Venezuela. To compensate former product lines to the west were reversed to import crude from the mid-west. In addition, every oil tank car was gathered up and placed into dedicated trains transshipping Texas and Oklahoma crude to these refineries and barges were seconded to this service. The ultimate solution was to build the Big Inch Pipeline (completed August 1943) to transport the crude, but even this was not enough resulting in the construction of the Little Big Inch specifically to expedite the transport of finished product (primarily avgas) produced in Texas and Louisiana to the UK.

In 1944 the three UK plants produced approximately 3% of the Western Allies high octane production. Due to the combined bomber offence, the UK was by far the largest consumer outside of the continental USA, taking about 27% of the Western Allies production (again not including the USSR). This means less than 15% of the Avgas consumed in the UK (by both the RAF and USAAF) was produced in the 3 UK plants. In other words, the British couldn't begin to meet the RAF’s needs, let alone supply the USAAF. Note that in late 1943 and 1944 Billingham was producing 150 PN which was never used in P-38s.




As noted in “Army Air Forces in World War II” by Craven and Cates Volume 2

_“Virtually all of the gasoline used in the United Kingdom from 1942 to 1945 came from American sources. The British were responsible for gasoline supply to the Middle East and China –Burma –India theaters.”_




If British avgas was somehow “bad,’ and there is not an iota of evidence to support this, the P-38 only had a 1 in 7 chance of receiving it. Judging by the enormous numbers of V-1710 failures someone must have been making a special effort to ensure the P-38 units were fueled exclusively with it.

To get an idea of the production imbalance in favor of the USA download the document “Official Munitions Production of the United States By Months, July 1, 1940- August 31, 1945” which contains a table showing the month by month production of avgas in the US as compared to foreign production. Official munitions production of the United States by months, July 1, 1940 - August 31, 1945. :: World War II Operational Documents
By the way, there’s a lot of other fascinating material in this document.

In any event the basic premise of Bad British Fuel as the cause of the Allison failures is bogus. The Allison’s problems were NOT limited to the ETO. This part of the myth was debunked by Daniel Whitney (author of Vees for Victory, the very comprehensive book on the V-1710) in the in his article “The Allison Time Bomb” in Volume 1 Number 2 of the “Torque Meter”
_“Not long after the introduction of the P-38J pilots in all theaters began experiencing unexpected and sudden failures of their engines.”_


_“The entire topic is further complicated because of the common impression that the failures occurred only in the ETO, so the problem “must have been poor quality British fuel” or the “low temperature at the high operating altitudes over the Continent.”_

He goes on to describe in some detail the problems experienced in the CBI.

The mode of failure was consistent. The outer most cylinders (1 and 6) received too rich a mixture, while the inner two (3 and 4) received too lean a mixture. The result was a failure of number 3 and 4 cylinders. This is can only be attributed to a flaw in the design. Looking at the intake manifold it is easy to see why. The air/fuel mixture has a straight shot into the number one cylinder while it has to make an abrupt 180 degree turn to reach the number 3 cylinder. The heavier than air fuel will tend to keep going in a straight line thus robbing the inner cylinders of enough fuel to avoid catastrophic consequences.

Due to the flow split and the two very tight elbows that I mentioned in a previous post, the fuel was separating out and pooling in the intake. This phenomenon was studied by the SAE in 1914! (the SAE paper is attached).






By the way the "Madame Queen" manifold is not a “turbulator” or a flow straighter (two diametrically opposed concepts) it is a second carburetor which uses its venturi to draw up and re-vaporize the fuel that has pooled at the bottom of the intake.

It should be noted that while the Allisons were blowing up at an incredible rate the RAF was at the same time engaged in the Battle of Berlin and as a consequent Merlins were flying thousands of sorties (>10,000) in four engine bombers to greater ranges without any reports of excessive failures. Not to mention the large numbers of sorties flown by R-1820s, R-1830s, R-2800s and V-1650s flying similar missions in that time frame. Applying Occam’s Razor leads to the conclusion that the fuel wasn’t at fault.

The venturi manifold was not designed in response to the crisis in the UK. The manifold had already designed and entered into production before the P-38 flew any missions over Germany. The first engines equipped with the new manifold were accepted by the AAF on November 28, 1943 at which time P-38 had only flown 7 missions over Germany and had only suffered 7 losses in total. Allison knew they had a problem before the P-38s went to the UK. As Dan Whitney notes “_Allison had previously realized that operations in very cold conditions were causing fuel condensation and so had introduced the new venturi gas pipe as a fix late in the fall.”_ (fall of 1943) . In Vees for Victory there are references to experiments being conducted on Allison engines in early 1943 to improve manifold design. As noted in this book the history of the development of the V1710 is a constant struggle to fix its fuel distribution problems. In fact the book states that the venturi pipe was designed as far back as December 1939 in an unsuccessful attempt to solve the even worse fuel distribution problems of the V-3420.

The fact that Allison had to resort to such a power robbing device shows how serious the problem was. It’s ironic to note that at the same time that Rolls Royce was concentrating their efforts on cleaning up the intake tract to reduce pressure loses and therefore free up wasted horsepower, Allison was headed in the opposite direction cluttering up their intake with a loss inducing device such as a venturi.

Meanwhile, as Whitney notes, in January 1944 Lockheed instituted an accelerated test program on the opposite side of the earth in sunny, warm California. ”The Battle of San Fernando Valley”. The 3 P-38J-15‘s involved blew up 14 engines! At least 2 of these had the venturi intake. It should be noted that air temperature at 25,000 feet is just as cold over Southern California in the summer as it is in England in the winter. It’s always cold at 25,000 feet, and any design that doesn’t take that into account has failed.

In summary:

The amount of bona fide British oil was insignificant.
What relatively small quantities of British avgas that were produced met the same specifications as all avgas.
The P-38 suffered problems all over the world.
The problems had surfaced well before P-38s flew any missions over Germany
As noted in a previous post, aromatics were added to US produced avgas in order to increase production well before the Allison started blowing up over Europe

Reactions: Bacon Bacon:
2 | Like Like:
3 | Informative Informative:
6 | Like List reactions


----------



## drgondog (Apr 24, 2020)

Shortround6 said:


> An old P-39 thread with a lot of pictures from the XP-39s time at Langley.
> 
> Bell P-39 Airacobra
> 
> ...



Hi Steve - I actually devote a lot of words re: Drag (surprise) in the new book. The Comparison table that I extracted was from NACA Advanced Confidential Report ACR L5A30, Roy Lange, February 1945, Pg 11. The tests were at the full scale wind tunnel at Langley for the P-40, P-38, F4F, F4U, F6F, P-63 and the P-51B. All a/c as received at Langley in stock condition. All inlets, exhaust stacks, gun ports, and Props removed - than added back one component at a time to obtain the Service Condition drag values.



The tests were run at 100mph at Sea Level and if you pull the Report you will see the slightly different RN due to the differences in Mean Aero Chord length of each wing.

NACA tested the P-63 which is cleaner than the P-39 due to the newer Low Drag wing = 0.0210 (vs 0.0209) of the P-51B for the UN-SEALED condition. After running 'unsealed' the respective values were 0.0171 vs 0.0173 - Note in propeller-less environment the advantage of the Meredith effect reduction to the drag of inlet scoop and flat plate effect is absent for the P-51B. This shows the nice aerodynamics achieved with the new wing and fuselage for the P-63.

For the casual viewer the relative CDtotal in Service Condition for P-40=0.0257; P-38=0.0293, F4F=0.0328, F4U=0.0284, F6F=0.0293, P-63=0.0210, P-51B=0.0209 (without benefit of cooling thrust obtained to offset the internal drag).

ADDED NOTE - after looking at Johnbr's excellent supply of XP-39/P-39 images, the CDhs I believe is the Total Calculated Drag Coefficient at the RN for the altitudes presented - which are significantly below SL Reynolds Number

Reactions: Like Like:
2 | Like List reactions


----------



## P-39 Expert (Apr 24, 2020)

varsity07840 said:


> You're digging too deep into '109 minutiae. The P-51 didn't need a new wing to accommodate an all .50 cal battery, four then six guns. The two nose guns P-36A evolved into the two wing gun P-36C and P-40 to the six guns P-40E without a new wing. The F4U evolved from a 2 wing gun prototype to a six .50 cal or four 20mm battery with the same wing. They all retained the same designation. The FW 190A8/R1 had four of its guns UNDER the wings not in them. Why was that?. The rest of the 190s you list had two of the guns (synchronized) in the WING ROOTS not in the WINGS. The original wing gun in the 190 was an MG 17. They were never able to increase the NUMBER of guns in the wing. Change in caliber was the best they could do. The P-39 wing could not accommodate a modern gun battery in the wings, hence the under wing guns as per the 109 and 190. The drag induced by the underwing guns on the 109 and 190 made them easy meat for Allied fighters. As far as the P-39Q goes, it didn't really matter. It was already a dog before the Q was introduced. Even the Soviets realized that and removed the gun tubs. Even Bell caught on and produced a batch of Qs without them.


P-39 was no dog especially by the time the N model was produced. Performance was so good that the AAF had to come up with something to retard it's performance so they added the podded .50 caliber MG. The Soviets removed ALL the wing guns, both .30s and the later .50s. Bell didn't "catch on", they built what the customer ordered/wanted. The Soviets didn't need wing guns and told the AAF as much.

Reactions: Funny Funny:
1 | Like List reactions


----------



## fubar57 (Apr 24, 2020)

LOL!!!!


----------



## DarrenW (Apr 24, 2020)

Shortround6 said:


> Coefficient of drag of a P-39 0.0217 from America's Hundred Thousand. I don't know where the Author got them.



Dean references this report in his book for that figure:

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930092637.pdf


----------



## drgondog (Apr 25, 2020)

P-39 Expert said:


> P-39 was no dog especially by the time the N model was produced. Performance was so good that the AAF had to come up with something to retard it's performance so they added the podded .50 caliber MG. The Soviets removed ALL the wing guns, both .30s and the later .50s. Bell didn't "catch on", they built what the customer ordered/wanted. The Soviets didn't need wing guns and told the AAF as much.



Bell's time to introduce what the field commanders wanted was early 1942 before the field commanders knew what they wanted. The War Plans Division in late 1941 and 1942 posited battlefield air superiority while performing Fast Attack role - the reason the Mustang in the form of A-36 snuck its big nose in the AAF tent - despite Oliver Echols' resistance to NAA getting in the Pursuit game.

The limiting known factor for the P-39 was never speed or maneuverability at low/medium altitude - it was the lack of range and external stores. It was already 'written off' as a primary AAF Pursuit (as was the P-40) in 1942 for future procurement. Bell and Curtiss survived in 1942-43 because we had to fight with what we had and there weren't enough P-38/P-47s to backfill the battlefield CAS requirements. They also were augmented by Lend Lease to USSR and our Allies while improvements kept them competitive for low to medium altitude use.

The final straw was the success of the Merlin 'experiment' in mid 1942 when the CAS acolytes viewed the Merlin Mustang as the answer to the fast, load carrying, maneuverable, long range CAS fighter that could achieve air superiority - the reason it was painted in to replace the P-39 and P-40. Only a few visionaries understood the escort potential of the P-51B until early 1943 so there was no fight by Strategic Air proponents until mid 1943 after Blitz Week - all were destined to be TAC CAS and Recce in ETO. 

The achilles heel for the P-39 from the inception was the wing. It was never conceptualized in 1937-1938 as anything but interceptor - and therefore had no room for growth for either internal fuel or external load and very little for internal armament. Price's decisions to encourage Bell to add wing armament capability was a desire to improve CAS effectiveness - not 'kill the program' 

It is kind of silly to suggest that Maj/LtC Price, the AAF Materiel Command P-39 Project manager wanted to kill the P-39.

Reactions: Bacon Bacon:
2 | Like Like:
2 | Agree Agree:
1 | Informative Informative:
3 | Like List reactions


----------



## varsity07840 (Apr 25, 2020)

P-39 Expert said:


> P-39 was no dog especially by the time the N model was produced. Performance was so good that the AAF had to come up with something to retard it's performance so they added the podded .50 caliber MG. The Soviets removed ALL the wing guns, both .30s and the later .50s. Bell didn't "catch on", they built what the customer ordered/wanted. The Soviets didn't need wing guns and told the AAF as much.



So, there was an AAF conspiracy to retard the performance of an aircraft they already bought? If it was such a world beater why didn't they replace those lousy P-38s with P-39Ns. I guess they did the same thing with the P-63.


----------



## Shortround6 (Apr 25, 2020)

I suggest some people go back and read the title of the thread and the first post. 

What the P-39 could or could not do in 1942 doesn't have a lot to do with what the XP-39 could do in the spring of 1939. 

or at least any more to do with each other than the P-40N had to do with XP-40 in it's original configuration





With it's different radiator setup, different airscoops, machine gun tubes/fairings and so on. XP-40 was supposedly incapable of exceeding 300mph in it's orginal configuration.

Reactions: Agree Agree:
2 | Like List reactions


----------



## P-39 Expert (Apr 25, 2020)

drgondog said:


> Bell's time to introduce what the field commanders wanted was early 1942 before the field commanders knew what they wanted. The War Plans Division in late 1941 and 1942 posited battlefield air superiority while performing Fast Attack role - the reason the Mustang in the form of A-36 snuck its big nose in the AAF tent - despite Oliver Echols' resistance to NAA getting in the Pursuit game.
> 
> The limiting known factor for the P-39 was never speed or maneuverability at low/medium altitude - it was the lack of range and external stores. It was already 'written off' as a primary AAF Pursuit (as was the P-40) in 1942 for future procurement. Bell and Curtiss survived in 1942-43 because we had to fight with what we had and there weren't enough P-38/P-47s to backfill the battlefield CAS requirements. They also were augmented by Lend Lease to USSR and our Allies while improvements kept them competitive for low to medium altitude use.
> 
> ...


Bell, like all other manufacturers, built what the AAF/Navy ordered, presumably what they wanted. The A-36 Apache was a simple placeholder to keep the production line running while the Merlin P-51B/C was being developed.

The only reason the P-39 (and P-40) were pruduced at all was to give the AAF modern fighters before the P-38 and P-47 were ready for combat in December '42 and May '43 respectively. After that these planes were kept in production to supply our allies under lend-lease.

There was no "escort" of the 8th AF in England until the P-47. Okay a few Spitfires which could actually get across the channel before they had to turn back. The P-47 had NO PROVISION WHATSOEVER for drop tanks until August of that year when they got a single 75 gallon drop tank for a plane that burned 190gallons per hour at cruise. By October P-38s were in England and two months later the Merlin P-51 was arriving. So the P-47 had about two months for any meaningful escort duty.


----------



## GregP (Apr 25, 2020)

To address post #134 a small bit, I don't believe anybody said the British were making "improper" fuel. At least, I didn't. I also haven't read it anywhere in here. I said it was not formulated the same as ours early-on (1941 - 1942-ish into early 1943), and it wasn't. There was nothing "improper" about it and the British were never less than technically savy. ... it was just different from the fuel supplied to domestic engine manufacturers, and the increased output of 100-Octane gasoline didn't happen overnight because someone planned 35+ new refineries in late 1941.

They actually DID have to build them, get them running, and figure out how to maintain production in the presence of ever-increasing demands for higher PN gasoline, which by itself tended to decrease volumetric output by as much as 26% unless ways could be devised to mitigate that reduction. Higher PN meant less gasoline from existing refineries. The introduction of aromatic additives (mainly cumene [mid 1942], xylidine, and napthas) largely helped defray this capacity reduction. In mid-1943 the Petroleum Administration of War approved the construction of a cycloversion facility (using napthas), but Borger didn't begin operations until July 1944. So, exactly when did the higher-aromatic fuel start to be seen in combat fuel tanks? I have not found anything stating that yet, but the FIRST cycloversion plant wasn't even operating until mid-1944 (Phillips Petroleum). Therefore, a DECISION made in Nov-Dec 1941 was implemented by mid-1944, and between those dates, the fraction of higher-performance fuels ramped ever-upward. I don't know exactly when a particular fighter group saw 115/145 or 105/150 fuel, but it wasn't likely until late 1943 - early 1944 in larger quantities. Certainly AFTER early ETO P-38 escort missions, anyway. Even the Early P-38Js were still being flown with fuels not best-suited for them.

The one hundred million gallons of high-performance aviation fuel came between 24 Dec 1942 and Aug 1945. One thousand 4-engine bombers making a six-hour flight used up 1,850,000 gallons of high-octane fuel. We flew that more than a few times in the last year and half of the war; never before that time. On a smaller scale, in the Pacific, 18 planes on one mission burned 11,600 gallons. To train ONE pilot, we used 12,500 gallons.

The production capacity for US fuel in late 1941 was small when compared with 1944. I believe that has been established. They built some 35+ refining plants between Dec 41 and mid-1944, maybe closer to 50.

Seems like TEL went from 2g/gal to 3 g/gal to 4 g/gal (May 42 is when the change was agreed upon ... not sure when it hit actual combat gas tanks) to some 6 g/gal (Feb 44 to produce 104/150 fuel) that managed to run well at high power settings, but separated and fouled plugs and had other bad effects at low power settings. They DID manage to come up with additives, as stated above. They settled on 115/145 fuel (4.6 g/gal TEL?) after trying the 150 out and finding the increased maintenance requirements from the use of 150.


----------



## tomo pauk (Apr 25, 2020)

P-39 Expert said:


> ...
> The P-47 had NO PROVISION WHATSOEVER for drop tanks until August of that year when they got a single 75 gallon drop tank for a plane that burned 190gallons per hour at cruise. By October P-38s were in England and two months later the Merlin P-51 was arriving. So the P-47 had about two months for any meaningful escort duty.



Already the P-47C have had a provision for a belly tank; 1st delivered on Spet 14th 1942. 1st The P-47Ds were self-deployed to UK via Iceland in August 1943 (two wing drop tanks each). The only P-47 without any external tankage was the P-47B, none of them being deployed away from CONUS.

It was far easier to turn the P-47 into a long range fighter than to try to do that with P-39.


----------



## Shortround6 (Apr 25, 2020)

P-39 Expert said:


> The P-47 had NO PROVISION WHATSOEVER for drop tanks until August of that year when they got a single 75 gallon drop tank for a plane that burned *190gallons* per hour at cruise




Source for the bolded part? Why on earth would the P-47 _cruise_ at the maximum continuous rating of the engine? 
The US tactical planning charts assume a speed of 210 IAS at 25,000ft which is about 315mph true depending on which calculator or formula you use. 

P-47s with R-2800-21 engines were rated at 225IAS (337.5mph true) at 25,000ft using 145 gallons an hour and 200 IAS (300mph true) at 25,000ft burning a mere 95 gallons an hour. Granted this is for a clean air plane ( I don't believe the chart is correct when it says either clean or with empty 200 gallon ferry tank) 

I would note that when the P-47D got the extra 65 gallons of internal fuel it's "radius" in the planning charts went up 100 miles with no drop tanks at all. Apparently "cruise" was using about 1 gallon for every 3 miles instead of the 1.9 miles per gallon you are claiming.

Reactions: Informative Informative:
1 | Like List reactions


----------



## P-39 Expert (Apr 26, 2020)

tomo pauk said:


> Already the P-47C have had a provision for a belly tank; 1st delivered on Spet 14th 1942. 1st The P-47Ds were self-deployed to UK via Iceland in August 1943 (two wing drop tanks each). The only P-47 without any external tankage was the P-47B, none of them being deployed away from CONUS.
> 
> It was far easier to turn the P-47 into a long range fighter than to try to do that with P-39.


The book "Thunderbolt" by Warren Bodie states that the 75 gallon tank was first used in combat on August 7, 1943. The 200+ gallon "udder" tanks were tried briefly but were unpressurized and didn't work at escort altitudes. 

The "Iceland" tanks were P-38 tanks and were for ferry (from US to England via Greenland and Iceland) and were jerry-rigged attachments since Republic had not yet devised pylon mounts. From the same book.

Combat radius for the P-47 and P-39N at 25000' were about the same with both having a 110 gal external tank.


----------



## P-39 Expert (Apr 26, 2020)

Shortround6 said:


> Source for the bolded part? Why on earth would the P-47 _cruise_ at the maximum continuous rating of the engine?
> The US tactical planning charts assume a speed of 210 IAS at 25,000ft which is about 315mph true depending on which calculator or formula you use.
> 
> P-47s with R-2800-21 engines were rated at 225IAS (337.5mph true) at 25,000ft using 145 gallons an hour and 200 IAS (300mph true) at 25,000ft burning a mere 95 gallons an hour. Granted this is for a clean air plane ( I don't believe the chart is correct when it says either clean or with empty 200 gallon ferry tank)
> ...


We continue to disagree on how much time the P-47 spent on normal (maximum cruise) power on escort missions in the ETO. During late '43 and early '44 when the Luftwaffe held air superiority I believe the P-47s spent the vast majority of their time at normal power for survival. 

The P-47D-25 with the extra 65 gallons of internal fuel wasn't available overseas until May '44 after air superiority had been won. These later D models had the wider propeller blades and had somewhat better climb numbers but were now relegated to the ground attack role.


----------



## Shortround6 (Apr 26, 2020)

I see, you just believe? with nothing to back it up?

The poor old obsolete fuel hog P-47 needs to run (cruise) at max continuous just survive over Europe at 25,000ft while the neglected( If not outright conspired against) P-39 can't fly as fast at full military power (5 or 15 minute rating) as the P-47 can cruise at. (unless we use the super N numbers) 
Something seems a bit off in that logic. 

Reason for bringing in the later P-47 was just to show what a difference 65-75 gallons of fuel made. I did say there were no drop tanks involved in the change of radius.

Reactions: Agree Agree:
1 | Like List reactions


----------



## drgondog (Apr 26, 2020)

[P-39 Expert, post: 1549345, member: 73913"]Bell, like all other manufacturers, built what the AAF/Navy ordered, presumably what they wanted. The A-36 Apache was a simple placeholder to keep the production line running while the Merlin P-51B/C was being developed.

*Nope - the A-36 was proposed in Dec 1941and accepted by AAF April 1942 - one month before the Rolls-Royce experiment was approved. The P-51A ordered in June 1942 was the placeholder for the P-51B and so covered in the contract which provided for 'conversion of the order to the P-51B-1.*

The only reason the P-39 (and P-40) were pruduced at all was to give the AAF modern fighters before the P-38 and P-47 were ready for combat in December '42 and May '43 respectively. After that these planes were kept in production to supply our allies under lend-lease.

*Nope- the P-39 and P-40 were in production before the P-38D, but the F-4 were in combat in May 1942. All of the P-38E and Fs initially went to 1st FG on west coast, then to ETO - first combat ops Aug 1942 from UK. The P-47C first combat was April 1943 in ETO. It was a simple matter of fight with what ya have, and when the P-47 and P-38 produced numbers to backfill specific combat units there weren't enough until 1944 to retire both from active AAF units. In May 1943 for example, there were only 3 P-47 groups operational, and four P-38 group plus several 'mixed P-40/P-38 FGs*

There was no "escort" of the 8th AF in England until the P-47. 
*Nope - The 1st (P-38 Aug 42), 4th (Spit Sep 42), 14th (P-38 Oct 42), 31st (Spit Aug 42) were flying escort. The 350th FG (P-400) and 82nd FG (P-38) and 78th FG were in training in UK when all were transferred to North Africa.*

Okay a few Spitfires which could actually get across the channel before they had to turn back. The P-47 had NO PROVISION WHATSOEVER for drop tanks until August of that year when they got a single 75 gallon drop tank for a plane that burned 190gallons per hour at cruise. By October P-38s were in England and two months later the Merlin P-51 was arriving. So the P-47 had about two months for any meaningful escort duty. 

*The first combat mission with the 200gal Ferry tank was 4th FG July 28, 1943. That said, from April 1943 through October 15th (when 55th FG P-38s went operational, there were seven operational P-47C/D FG in 8th AF - prior to the centerline tank conversions the 4th, 56th, 78th were flying escort and sweeps into Holland, Belgium and France. With the 75gal tanks in August the combat radius of the P-47 was 230 mi, with the 110 in October it was extended to 275mi - Despite your presumption that the P-47 performed only 'two months of meaningful escort duty', the victory totals in 1943 for each were P-47=402; P-38=29; Spitfire=7 P-51B=8 for 1943 ETO combat ops. The Spit and Mustang only flew one month respectively in 1943.*

Reactions: Like Like:
1 | Informative Informative:
5 | Like List reactions


----------



## drgondog (Apr 26, 2020)

P-39 Expert, post: 1549473, member: 73913"]We continue to disagree on how much time the P-47 spent on normal (maximum cruise) power on escort missions in the ETO. During late '43 and early '44 when the Luftwaffe held air superiority I believe the P-47s spent the vast majority of their time at normal power for survival. 

*Max Continuous Cruise Power was Not the setting for escort operations. The cruise throttle and RPM were at much lower to target max cruise radius.* 

The P-47D-25 with the extra 65 gallons of internal fuel wasn't available overseas until May '44 after air superiority had been won. These later D models had the wider propeller blades and had somewhat better climb numbers but were now relegated to the ground attack role.

*The 56th, 78th, 350th, 356th FG - all of which were first to receive the bubble canopy/370 gal internal tank would be greatly surprised at that comment. All continued escort duties well into October and the 56th through VE Day.*

Reactions: Like Like:
1 | Informative Informative:
4 | Like List reactions


----------



## Shortround6 (Apr 26, 2020)

drgondog said:


> With the 75gal tanks in August the combat radius of the P-47 was 230 mi, with the 110 in October it was extended to 275mi



radius without the tanks (clean) was supposed to be 125 miles, so again, the implication that the 75 gallon drop tank wasn't of much use or that the P-47 cruised using 190 gallons an hour does not seem to be supported by either documents or operational use.


----------



## tomo pauk (Apr 26, 2020)

P-39 Expert said:


> The book "Thunderbolt" by Warren Bodie states that the 75 gallon tank was first used in combat on August 7, 1943. The 200+ gallon "udder" tanks were tried briefly but were unpressurized and didn't work at escort altitudes.
> The "Iceland" tanks were P-38 tanks and were for ferry (from US to England via Greenland and Iceland) and were jerry-rigged attachments since Republic had not yet devised pylon mounts. From the same book.



The official manual for the P-47C notes that external tank facility is there. That in the ETO the intended user took a few months to took advantage of that was no fault of P-47. The intended user in SWP jumped into the opportunity, while not wanting any P-39 long before P-47 arrived, due to the lack of range of P-39.



> Combat radius for the P-47 and P-39N at 25000' were about the same with both having a 110 gal external tank.



Not if both of them are to fly at 300+ mph TAS at 25000 ft.
BTW - the drink is on me when you post a picture of a P-39 with 110 gal drop tank.



> ... With the 75gal tanks in August the combat radius of the P-47 was 230 mi, with the 110 in October it was extended to 275mi



Bill - your figures seem to come short by 100 miles? 330 miles with 75 gal DT, 375 miles with 110 DT.



> - Despite your presumption that the P-47 performed only 'two months of meaningful escort duty', the victory totals in 1943 for each were *P-47=402*; P-38=29; Spitfire=7 P-51B=8 for 1943 ETO combat ops. The Spit and Mustang only flew one month respectively in 1943.



Bingo.


----------



## P-39 Expert (Apr 26, 2020)

Shortround6 said:


> I see, you just believe? with nothing to back it up?
> 
> The poor old obsolete fuel hog P-47 needs to run (cruise) at max continuous just survive over Europe at 25,000ft while the neglected( If not outright conspired against) P-39 can't fly as fast at full military power (5 or 15 minute rating) as the P-47 can cruise at. (unless we use the super N numbers)
> Something seems a bit off in that logic.
> ...


P-47 max continuous cruise was 360mph (clean) per the pilot's manual while the P-39N max speed at the same altitude was 370-375mph depending on the test.


----------



## P-39 Expert (Apr 26, 2020)

tomo pauk said:


> The official manual for the P-47C notes that external tank facility is there. That in the ETO the intended user took a few months to took advantage of that was no fault of P-47. The intended user in SWP jumped into the opportunity, while not wanting any P-39 long before P-47 arrived, due to the lack of range of P-39.
> 
> 
> 
> ...


I'm looking at the manual for the P-47B/C/D/G right now and there is no mention at all of any external tank other than the 200gal unpressurized tank that was proven unsuitable for high altitudes. None.

Regarding the 110gal external tank, it is quoted in both books by Edwards Park on operations in NG in '42 and '43. He was very specific. He was there as a P-39 pilot in the 8th fighter group.


----------



## tomo pauk (Apr 26, 2020)

duplicate


----------



## tomo pauk (Apr 26, 2020)

P-39 Expert said:


> I'm looking at the manual for the P-47B/C/D/G right now and there is no mention at all of any external tank other than the 200gal unpressurized tank that was proven unsuitable for high altitudes. None.



The P-47 in the field took advantage of the factory-made external tank facility, running contrary to the claim:
"The P-47 had NO PROVISION WHATSOEVER for drop tanks until August of that year..."

Granted, the 200 gal unpressurized tank was unsuitable for high altitudes, but it was there and could (and was) used to extend the range in combat ops until better and more refined solution was in the place.



> Regarding the 110gal external tank, it is quoted in both books by Edwards Park on operations in NG in '42 and '43. He was very specific. He was there as a P-39 pilot in the 8th fighter group.



I've offered a drink for a good reason.


----------



## drgondog (Apr 26, 2020)

tomo pauk said:


> Bill - your figures seem to come short by 100 miles? 330 miles with 75 gal DT, 375 miles with 110 DT.


HI Tomo - until the D-15/-16 arrived in ETO in late winter/spring 1944, only the very lengthy depot mods on the wing enable pylon and fuel feed from the wing tanks. Until then all the single 75, 110 and flat 150gal were carried on C/L rack


----------



## tomo pauk (Apr 26, 2020)

drgondog said:


> HI Tomo - until the D-15/-16 arrived in ETO in late winter/spring 1944, only the very lengthy depot mods on the wing enable pylon and fuel feed from the wing tanks. Until then all the single 75, 110 and flat 150gal were carried on C/L rack



I know. The drop tank vs. range combinations are for a single, belly-mounted drop tanks as could've been found on P-47s in 1943 in the ETO.


----------



## P-39 Expert (Apr 26, 2020)

drgondog said:


> [P-39 Expert, post: 1549345, member: 73913"]Bell, like all other manufacturers, built what the AAF/Navy ordered, presumably what they wanted. The A-36 Apache was a simple placeholder to keep the production line running while the Merlin P-51B/C was being developed.
> 
> *Nope - the A-36 was proposed in Dec 1941and accepted by AAF April 1942 - one month before the Rolls-Royce experiment was approved. The P-51A ordered in June 1942 was the placeholder for the P-51B and so covered in the contract which provided for 'conversion of the order to the P-51B-1.*
> 
> ...



What I read says the A-36 first flew in Sept '42 and entered combat in November. P-51A production (only 310 built) began March '43, switches to P-51B production in May '43. No P-51 series production occurred between October '42 and March '43 when the A-36 was being produced. Meaning the A-36 was a placeholder to keep production going until the P-51B could begin production.

Generally accepted dates of combat for the P-38 are very late '42 for Operation Torch and the SWP area. The earlier D/E models may have seen a little combat but had inferior performance to the later F/G models.

Regarding 8th AF escort the first P-47 escort mission is listed as April 30 and was the first 8thAF mission to use at least 100 bombers. I also said that prior to that they were escorted by Spitfires which had ridiculously short range. What escort missions did the P-38s fly before they were transferred to N. Africa for Torch?

Regarding the 200gal FERRY tank, it was just that. Not suitable for combat at escort altitude since it was unpressurized. Most don't consider escort missions to Holland, Belgium and a sliver of France to be meaningful. A Spitfire could take them that far. Even after getting the 110gal external tank they could only go 275 miles, about halfway to Berlin.

I stand by my original statements.


----------



## tomo pauk (Apr 26, 2020)

P-39 Expert said:


> ...
> 
> Regarding the 200gal FERRY tank, it was just that. Not suitable for combat at escort altitude since it was unpressurized. Most don't consider escort missions to Holland, Belgium and a sliver of France to be meaningful. A Spitfire could take them that far. Even after getting the 110gal external tank they could only go 275 miles, about halfway to Berlin.



Make that 375 miles - map.

Reactions: Like Like:
1 | Like List reactions


----------



## Reluctant Poster (Apr 26, 2020)

I have attached the document this came from.

Reactions: Bacon Bacon:
1 | Like Like:
1 | Informative Informative:
5 | Like List reactions


----------



## eagledad (Apr 26, 2020)

P-39 Expert

The 1st FG flew 3 bomber escort missions from England on 9/25/42 (Maupertus), 10/2/42(St Omer) and 10/9/42 (Lille).

FYI

Eagledad

Reactions: Informative Informative:
2 | Like List reactions


----------



## Reluctant Poster (Apr 26, 2020)

Shortround6 said:


> Greg, please go over the time line for the P-38. There are two different issues with fuel at different times.
> 
> The early US fuel had little or no aromatics, this was in 1940 or so, If you want 100/125 or 100/130 you have to use aromatics. At least if you want to make fuel on a large scale.
> 
> ...


Info on the production of the various grades of fuel. Note that the 98 and 99 grades mostly stayed in the US. Also note the limited use of 6.0 cc TEL and the even more limited production of 115/145.

Reactions: Bacon Bacon:
1 | Like Like:
1 | Informative Informative:
1 | Like List reactions


----------



## DarrenW (Apr 26, 2020)

P-39 Expert said:


> Combat radius for the P-47 and P-39N at 25000' were about the same with both having a 110 gal external tank.





P-39 Expert said:


> Regarding the 110gal external tank, it is quoted in both books by Edwards Park on operations in NG in '42 and '43. He was very specific. He was there as a P-39 pilot in the 8th fighter group.



Not trying to disprove what you are claiming here, but when did the P-39N begin carrying the 110 gal external tank? The source I have concerning the P-47 with 108 gallon tanks states:

_Sep, 1943-In the UK locally produced 108 gallon metal drop tanks for the P-47 start to become available, and also the locally-produced 108 gallon paper fuel tanks are now being delivered in increased quantity. These tanks give the P-47 a theoretical escort radius of 375 miles. _

and...

_Sep 27,1943-P-47s with drop tanks escort B-17s all the way to Emden, Germany, and destroy 21 enemy aircraft for the loss of one._

_(America's Hundred-Thousand, page 288 - Francis Dean)_

Anything similar to these direct quotes concerning the P-39 in the books you mentioned?


----------



## drgondog (Apr 26, 2020)

P-39 Expert, post: 1549528, member: 73913"]What I read says the A-36 first flew in Sept '42 and entered combat in November. P-51A production (only 310 built) began March '43, switches to P-51B production in May '43. No P-51 series production occurred between October '42 and March '43 when the A-36 was being produced. Meaning the A-36 was a placeholder to keep production going until the P-51B could begin production.

*Yes, No, No, and No.
1st production A-36 first flew Sept, 21 1942. 1st P-51A began production in November 1942, and first flew February 3, 1943. 1st P-51B-1 began in December 1942 and was completed in March, 1943 save engine not delivered until late April, then acceptance flight on May 5, 1943. At one time the 'placeholder A-36' and the P-51A and the P-51B-1 were all on the line at Inglewood at the same time.*

*A-36 began combat ops in June 1943, the (F-6) P-51-2-NA in December 1942, P-51A in November 1943, P-51B in December 1943.*

*IMPORTANT facts - the A-36 contract was dated April 1942, the P-51A contract was dated June 1942, The P-51B-5 contract was dated October 1942 (and serial number sequence began at the end of the P-51A) but the first P-51B (B-1) contract (dated 8-26-1942) was before the FIRST flight of the A-36A. If you devote any brain cells at all you have to understand that the Army had bought in to the Merlin Mustang before the first A-36 was delivered and the P-51A was in serial production - *

Generally accepted dates of combat for the P-38 are very late '42 for Operation Torch and the SWP area. The earlier D/E models may have seen a little combat but had inferior performance to the later F/G models.

*To those that don't research the topic, or have a different notion of combat that DOES Not include shooting down, a Japanese fighter in the Aleutians (8-4-42 by 54th FS P-38E) or over Iceland (8-14-42 by 27FS/1FG), then stand by your vague statement about 'generally accepted'.*

* The 1st FG P-38Fs began combat ops on 29 August 1942 with a Sweep by 94FS over French coast. The 14th FG flew first Sweep on October 2nd*

Regarding 8th AF escort the first P-47 escort mission is listed as April 30 and was the first 8thAF mission to use at least 100 bombers. I also said that prior to that they were escorted by Spitfires which had ridiculously short range. What escort missions did the P-38s fly before they were transferred to N. Africa for Torch?

** April 8, 1943 for 4th, 56th and 78th FG P-47C. Rodeo between Dunkirk and Sangette.
September 1, 1942 for 1st FG P-38F. Sweep French/Belgian coast. During September the 1st FG flew Sweeps ahead of inbound VIII BC task forces over France and Belgium. First escort on 26 September but recalled due to weather. 2 October was first complete escort mission to Meaulte. 9 October to Lille, 
October 21, 1942 for 14th FG 1st escort. Last mission before both the 1st, 14th and 82nd FG P-38F, 31st and 52nd FG Spitfire, and 350th P-39s prepared for move to North Africa. *

Regarding the 200gal FERRY tank, it was just that. Not suitable for combat at escort altitude since it was unpressurized. Most don't consider escort missions to Holland, Belgium and a sliver of France to be meaningful. A Spitfire could take them that far. Even after getting the 110gal external tank they could only go 275 miles, about halfway to Berlin.

*No, in your vernacular it was a 'placeholder'. That said, its first use with it on July 28 when 4th FG penetrated German airspace and ambushed a gaggle of forming Bf 10s and 109s near Emmrich. Scored 9-1-6 for the loss of 1. 
"Most don't consider escort missions to Holland, Belgium and France to be meaningful". *

*First, the Spitfire could NOT take them past the coastline for any stretch and were used for Penetration escort, with P-47s picking up Target and Withdrawal. *

*Second, the entire fall/winter 1942 and spring 1943 was all about gaining strength and tactics for 8th AF BC and FC. You may choose to cite combat missions prior to Blitz Week and first Schweinfurt - Regensburg as "meaningless" - but why? True that the escort capability was woefully short compared to five months later - but the escort tactics of relay for Penetration/Withdrawal escort, formation assembly and navigation, friendly bomber Group ID recognition, Command radio co-ordination, combat experience, formation experience, flying in bad weather were HUGE factors in late 1943 through D-Day.*

*Most observers of Daylight bombing campaign in the ETO realize how important those factors were to introduce the P-51B to combat ready and skilled AAF fighter pilots who had to do what no other Air Force did, or could do - namely fight over German targets in Germany, Czechoslovakia, Austria, Rumania - taking off and returning in bad weather.*

*Personally, I would say they were Very Meaningful. *

I stand by my original statements.

*Stand Tall, at ease, smoke em' if you have 'em.*

Reactions: Like Like:
1 | Agree Agree:
3 | Like List reactions


----------



## drgondog (Apr 26, 2020)

DarrenW said:


> Not trying to disprove what you are claiming here, but when did the P-39N begin carrying the 110 gal external tank? The source I have concerning the P-47 with 108 gallon tanks states:
> 
> _Sep, 1943-In the UK locally produced 108 gallon metal drop tanks for the P-47 start to become available, and also the locally-produced 108 gallon paper fuel tanks are now being delivered in increased quantity. These tanks give the P-47 a theoretical escort radius of 375 miles. _
> 
> ...



Not taking exception - but the 'theoretical' 375 mile combat radius was for the P-47s modified at Depot with major wing mods to carry two 110gal tanks underwing. Looking at late March at earliest for group level TO&E of P-47D-15/-16 production equivalents.


----------



## drgondog (Apr 26, 2020)

Reluctant Poster said:


> View attachment 578960
> 
> 
> View attachment 578961
> ...



It is a good article But the first operational use of the 200gal Ferry tank was on the 28th.

The 24th was the Heroya strike and zero P-47s even bothered to leave their bases. The 25th through 27th saw VIII FC fly diversionary escort to B-26s abd sweeps along the coast. 

The 28th strike was to Kassel and Oschersleben and the 4th flew an early Penetration Sweep in front of the 1st TF, flew into Germany and then doubled back to hammer a forming LW attack force over eastern Holland.


----------



## GregP (Apr 26, 2020)

Hi Reluctant Poster,

Regarding post #163, where did you find those data? I tried searching for the indicated source.

Very curious, and thank you for posting that!


----------



## DarrenW (Apr 26, 2020)

drgondog said:


> Not taking exception - but the 'theoretical' 375 mile combat radius was for the P-47s modified at Depot with major wing mods to carry two 110gal tanks underwing. Looking at late March at earliest for group level TO&E of P-47D-15/-16 production equivalents.



Ok thanks Bill for the clarification. I believe Emden was roughly a 600 mile round trip.

Still would love to see the actual passages about the P-39 carrying the 110 gallon belly tank. I only saw references for the 75 gallon variety.


----------



## P-39 Expert (Apr 26, 2020)

DarrenW said:


> Ok thanks Bill for the clarification. I believe Emden was roughly a 600 mile round trip.
> 
> Still would love to see the actual passages about the P-39 carrying the 110 gallon belly tank. I only saw references for the 75 gallon variety.


Get Park's two books, "Nanette" and "Angels Twenty". First one is fiction, second based on fact. Same setting, same time. He was there. Quite specific about the 110gal tank on multiple occasions. Makes sense, almost the ideal size for a plane with 120gal internal. Everything else he says about the P-39 is dead on.


----------



## DarrenW (Apr 26, 2020)

P-39 Expert said:


> Get Park's two books, "Nanette" and "Angels Twenty". First one is fiction, second based on fact. Same setting, same time. He was there. Quite specific about the 110gal tank on multiple occasions. Makes sense, almost the ideal size for a plane with 120gal internal. Everything else he says about the P-39 is dead on.



Ok I'll definitely look into that Expert...thanks.


----------



## DarrenW (Apr 26, 2020)

drgondog said:


> Not taking exception - but the 'theoretical' 375 mile combat radius was for the P-47s modified at Depot with major wing mods to carry two 110gal tanks underwing. Looking at late March at earliest for group level TO&E of P-47D-15/-16 production equivalents.



Bill - Does your book happen to have an accurate map showing the range of the various escort fighters? I ask this because you have explained in the past that most if not all maps found in various sources are incorrect as far as radius of action concerning the P-47 with different fuel loads.


----------



## wuzak (Apr 26, 2020)

P-39 Expert said:


> Get Park's two books, "Nanette" and "Angels Twenty". First one is fiction, second based on fact. Same setting, same time. He was there. Quite specific about the 110gal tank on multiple occasions. Makes sense, almost the ideal size for a plane with 120gal internal. Everything else he says about the P-39 is dead on.



So one of your sources is fiction, and the other is "based on fact"?

Also, generally something described as "based on fact" is fiction as well.

Reactions: Agree Agree:
3 | Like List reactions


----------



## fubar57 (Apr 26, 2020)

....like movies of the week


----------



## fubar57 (Apr 26, 2020)

Interesting quotes in the book "Angels Twenty...









​Are there pictures of these 110 gallon drop tanks in the book or are we relying on 40 year old memory?


----------



## pbehn (Apr 26, 2020)

wuzak said:


> So one of your sources is fiction, and the other is "based on fact"?
> 
> Also, generally something described as "based on fact" is fiction as well.


The Sound of Music was based on fact, well it was a fact that there was a war in Europe, but I don't think people burst into song so often, TBH.


----------



## Shortround6 (Apr 26, 2020)

pbehn said:


> The Sound of Music was based on fact, well it was a fact that there was a war in Europe, but I don't think people burst into song so often, TBH.


Actually Von Trapp had been Austria-Hungary's most successful submarine commander in WW I and his first wife (mother of 7 of the children) was Robert Whitehead's (inventor of the self propelled torpedo) granddaughter.

Reactions: Like Like:
2 | Informative Informative:
2 | Like List reactions


----------



## P-39 Expert (Apr 26, 2020)

drgondog said:


> P-39 Expert, post: 1549528, member: 73913"]What I read says the A-36 first flew in Sept '42 and entered combat in November. P-51A production (only 310 built) began March '43, switches to P-51B production in May '43. No P-51 series production occurred between October '42 and March '43 when the A-36 was being produced. Meaning the A-36 was a placeholder to keep production going until the P-51B could begin production.
> 
> *Yes, No, No, and No.
> 1st production A-36 first flew Sept, 21 1942. 1st P-51A began production in November 1942, and first flew February 3, 1943. 1st P-51B-1 began in December 1942 and was completed in March, 1943 save engine not delivered until late April, then acceptance flight on May 5, 1943. At one time the 'placeholder A-36' and the P-51A and the P-51B-1 were all on the line at Inglewood at the same time.*
> ...


I just can't stay away.

The P-51/A-36 production dates were straight from AHT. Yours are different.

Combat dates for the P-38 were written to be fairly general. They don't include one victory in the Aleutians or one in Iceland. 

Regarding the P-38 escort missions in England before they were moved to N. Africa, you are saying there were three? 2 October, 9 October and 21 October? Three whole missions? 

And I still don't consider escort missions to Holland, Belgium and a sliver of France to be meaningful. Not when your main target is Berlin.


----------



## Reluctant Poster (Apr 26, 2020)

GregP said:


> Hi Reluctant Poster,
> 
> Regarding post #163, where did you find those data? I tried searching for the indicated source.
> 
> Very curious, and thank you for posting that!


The first table can be found within this document
Official munitions production of the United States by months, July 1, 1940 - August 31, 1945. :: World War II Operational Documents 
It is a treasure trove of inforamtion
The second table is from "A history of the Petroleum Administration for War" which I previously posted links to

Reactions: Informative Informative:
1 | Like List reactions


----------



## fubar57 (Apr 26, 2020)

Someone said back in Post #142 that there were "no escort missions" until the P-47 showed up. 3 is a number

Reactions: Like Like:
1 | Agree Agree:
1 | Like List reactions


----------



## Shortround6 (Apr 26, 2020)

P-39 Expert said:


> And I still don't consider escort missions to Holland, Belgium and a sliver of France to be meaningful. Not when your main target is Berlin.


And just how many missions did the 8th AIr Force fly to Berlin in the fall of 1942? 

Main target was German infrastructure/manufacturing plants. 

First raid on Berlin by the 8th Air Force was March 4th 1944?

tough to escort bombers to Berlin when the bombers aren't going there.

Reactions: Like Like:
3 | Agree Agree:
1 | Winner Winner:
1 | Informative Informative:
1 | Like List reactions


----------



## Reluctant Poster (Apr 26, 2020)

Shortround6 said:


> And just how many missions did the 8th AIr Force fly to Berlin in the fall of 1942?
> 
> Main target was German infrastructure/manufacturing plants.
> 
> ...



As I have pointed out in previous posts the real bombing of Germany by the 8th AF didn't start until Big Week in February 1944 ( I posted a chart of distances to target by date). The number of deep penetrations of Germany airspace could be counted on the fingers of one hand prior to Big Week.
Here is a active map shown the timelines by month of RAF and USAAF bombing campaigns:

 

It seems to match fairly well with the US Bomb tonnages dropped on Germany as shown in the Statistical Digest

Reactions: Bacon Bacon:
2 | Winner Winner:
1 | Informative Informative:
3 | Like List reactions


----------



## P-39 Expert (Apr 27, 2020)

fubar57 said:


> Interesting quotes in the book "Angels Twenty...
> 
> View attachment 579011
> 
> ...


No pictures in either book, just a few crappy drawings. And Park is not kind to the P-39, his whole premise is how hard these guys had it in NG. But their daily life, technically how the missions were flown, training, etc are interesting.


----------



## DarrenW (Apr 27, 2020)

DarrenW said:


> Ok I'll definitely look into that Expert...thanks.



P-39 Expert:
I tried searching for any reference to 110 gallon drop tanks in "Angels Twenty" using the Google search engine and came up with nothing. Would you be kind enough to post the passage(s) yourself? I have no interest in purchasing the book in order to find such obscure information.


----------



## drgondog (Apr 27, 2020)

"P-39 Expert, post: 1549684, member: 73913"]I just can't stay away.

The P-51/A-36 production dates were straight from AHT. Yours are different.

*And yet mine is 100% correct, extracted from the North American Aviation "O" Report which details by model number, each contract number, the NAA assigned serial number range, the AAF assigned serial number range, the blocks within each Model, cancellations and transfers to other projects.
Dean did a nice job - not sure he had the 1000's of NAA docs and correspondence that I have - BUT - if you are interested you will find that Robert Gruenhagen made VERY few mistakes and these numbers are correct. Seek truth in Mustang-The Story of the P-51, start on page 193. The data 100% matches NAA O Report for NA-73 through NA-150 to include ALL versions of the Mustang and P-82.*

*In addition I have the first flight dates and NAA pilot for each model as well as Bob Chilton's Logbook (copy - not original). Are those types references up to your standards?*

Combat dates for the P-38 were written to be fairly general. They don't include one victory in the Aleutians or one in Iceland. 

*And yet again, you aren't digging enough into say, USAF Study 85 - or perhaps Olynyk's Stars and Bars and derivative victory credits lists - among other available resources. The combat encounters I offered to you are specific and relevant to the combat operations of the P-38. Reflect on your scholarship expertise or the reliability of the sources that you have at hand.*

Regarding the P-38 escort missions in England before they were moved to N. Africa, you are saying there were three? 2 October, 9 October and 21 October? Three whole missions? 

*Three that I picked out so that you have clues to build on.*

And I still don't consider escort missions to Holland, Belgium and a sliver of France to be meaningful. Not when your main target is Berlin.

*And yet you seem to have overlooked opinions of such folks as LeMay, Spaatz, Arnold, Eaker among others that may possibly have a more knowledgeable and fact based opinion than your 'consideration or opinion'?*

Reactions: Like Like:
3 | Winner Winner:
2 | Informative Informative:
1 | Like List reactions


----------



## Shortround6 (Apr 27, 2020)

Regarding the use of P-38s escorting to coastal targets in the fall of 1942. 
It was common practice of the Americans (and British) to send new units (squadrons/groups) on short range missions to coastal targets for their first few missions to give them a bit of experience and get some of the bugs out. The first few missions by Mustangs in Dec of 1944 were to coastal targets or targets in north western France. 

The P-38 was viewed in 1942, rightly or wrongly, as America's best _available_ fighter. However it was also available in the fewest numbers. The P-47 and P-51 (Merlin) may well have been viewed as even better but they were months away from combat (a year is also 12 months long so things obviously can change from month to month) So P-38s were sent to areas of high importance even though in small numbers. The Squadron in Iceland was helping protect the convoy routes and the single victory (shared with a P-40) was a FW 200. Trying to intercept a single plane (and the Germans weren't even flying one a day at times) over the North Atlantic called for a lot of luck, but the effort could not be done away with. Nobody knew how much a diversion the Aleutian campaign was or was not to the Japanese and so had to be defended against. These were not out of the way places to hide problem aircraft, at least not in 1942. 
For operation Torch the Americans had four fighters, P-38s, P-39s (with 8.80 gears) and the Allison P-40s (with 8.80 gears) and the Merlin P-40s. Even if they wanted, complete fighter groups with P-47s or Allison powered planes with 9.60 gears were months away. The P-38s were not pulled from Europe because they could not hack it there (nobody really knew if they could or couldn't) but because they were_ thought_ to give the Americans their best chances against the Germans in North Africa. As spring and summer rolled around The P-38 groups in NA/Med got newer aircraft as did the P-39 and P-40 groups. But the main effort of the Air Force was supporting the Campaign in North Africa and the the invasion/s of Italy. The 8th Air Force was building strength and experience. At the time of operation Husky (Invasion of Sicily, July 10th 1943) the Northwest African Strategic Airforce had four bomb groups, each with four squadrons, of B-17s, two bomb groups, each with four squadrons of B-25s and 3 bomb groups each with four squadrons of B-26s. There were three P-38 fighter groups each with 3 squadrons and one P-40 group with 3 squadrons. 

further units are here.

Reactions: Like Like:
1 | Informative Informative:
1 | Like List reactions


----------



## drgondog (Apr 27, 2020)

DarrenW said:


> P-39 Expert:
> I tried searching for any reference to 110 gallon drop tanks in "Angels Twenty" using the Google search engine and came up with nothing. Would you be kind enough to post the passage(s) yourself? I have no interest in purchasing the book in order to find such obscure information.



I could be wrong but I don't recall that c/l rack on the P-39 was structurally sound for any load > 500 pounds or a 75 gallon tank.


----------



## Shortround6 (Apr 27, 2020)

There was a ferry tank





AHT also lists weight for a 95 gallon (?) tank.
Quick google search turns up nothing for photos of larger than 75 gallon tanks except for the ferry tank.

Edit, weight allowances for ferrying might be different than for 'normal" flying and often when ferrying other things were taken out to help keep the gross weight somewhat in bounds. 
(like no ammo and some times certain guns or other equipment removed) end edit.

Reactions: Informative Informative:
3 | Like List reactions


----------



## drgondog (Apr 27, 2020)

Reluctant Poster said:


> As I have pointed out in previous posts the real bombing of Germany by the 8th AF didn't start until Big Week in February 1944 ( I posted a chart of distances to target by date). The number of deep penetrations of Germany airspace could be counted on the fingers of one hand prior to Big Week.
> 
> Do attacks on Gdanyia, Danzig, Oslo, Brunswick, Hamburg, Regensburg, Oschersleben, Marienburg, Halberstadt, Heroya (as separate targets, not number of attacks)
> fit on the fingers of an as yet unidentified 'one hand'? Asking for a friend.





Shortround6 said:


> There was a ferry tank
> View attachment 579106
> 
> 
> ...


Ferry tanks - particularly like the 'slipper' type shown were capable of being larger because they did not require sway braces nor did they not cause undue bending moments to the surrounding fuselage from aero and maneuvering loads.

Reactions: Agree Agree:
1 | Like List reactions


----------



## BiffF15 (Apr 27, 2020)

Shortround6 said:


> There was a ferry tank
> View attachment 579106
> 
> 
> ...



SR6,

Nice shot, guessing Buffalo, NY due to billboard sign saying "stay left enter Canada"...

Cheers,
Biff


----------



## P-39 Expert (Apr 27, 2020)

DarrenW said:


> P-39 Expert:
> I tried searching for any reference to 110 gallon drop tanks in "Angels Twenty" using the Google search engine and came up with nothing. Would you be kind enough to post the passage(s) yourself? I have no interest in purchasing the book in order to find such obscure information.


Here you go.

Reactions: Informative Informative:
1 | Useful Useful:
1 | Like List reactions


----------



## fubar57 (Apr 27, 2020)

I have 16 books about the P-39 and have yet to find a photo of one with a 110 gallon tank. One mention of a P-39F that could carry one and a line drawing


----------



## pbehn (Apr 27, 2020)

fubar57 said:


> I have 16 books about the P-39 and have yet to find a photo of one with a 110 gallon tank. One mention of a P-39F that could carry one and a line drawing


Obviously more books needed.

Reactions: Like Like:
2 | Funny Funny:
1 | Like List reactions


----------



## DarrenW (Apr 27, 2020)

P-39 Expert said:


> Here you go.



Thank you very much. Does the book give a time frame that these tanks were first fitted? I'm trying to determine if the P-39 used them operationally before the P-47 were fitted with 108 gallon tanks (September 1943).

From my limited research it seems that the 108 gallon tanks (manufactured in England) were made of paper, while the 110 gallon tanks were metal. They have almost identical capacities but were clearly different in many aspects:





110 gallon metal tanks






108 gallon paper tank


----------



## P-39 Expert (Apr 28, 2020)

DarrenW said:


> Thank you very much. Does the book give a time frame that these tanks were first fitted? I'm trying to determine if the P-39 used them operationally before the P-47 were fitted with 108 gallon tanks (September 1943).
> 
> From my limited research it seems that the 108 gallon tanks (manufactured in England) were made of paper, while the 110 gallon tanks were metal. They have almost identical capacities but were clearly different in many aspects:
> 
> ...


No time frame for the tanks, but the writer arrived at Port Moresby in January '43. They couldn't have been the paper tanks as they were reuseable. 


fubar57 said:


> I have 16 books about the P-39 and have yet to find a photo of one with a 110 gallon tank. One mention of a P-39F that could carry one and a line drawing



Can you post the line drawing?


----------



## drgondog (Apr 28, 2020)

"P-39 Expert, post: 1549946, member: 73913"]No time frame for the tanks, but the writer arrived at Port Moresby in January '43. They couldn't have been the paper tanks as they were reuseable.

*True - 108gal paper tanks were only made and used in UK. The initial allocation of US made 110gal steel combat tanks went to UK for 8th/9th AF P-47s'
That said Kenney was very successful and aggressive at subcontracting Australian companies to build a variety of tanks - none of which were 'combat rated' per Materiel Command specs - but nobody cared in SWP, particularly since the usage was largely over water.*

*As near as I can tell the P-39D/F was the first model with centerline rack stressed for 500 pound bomb. With the plumbing to feed fuel, a 75 gallon steel tank and the 175 gallon slipper tank (for ferry) could be carried. I have never seen a P-39 operational with anything like a 110 gallon combat tank as used in ETO/MTO in late 1943. That said, it means nothing that I have 'not seen one'. The only established fact is that a.) P-39s conducted FB sweeps with external bomb load - so the sway braces were in place on the C/L rack, and b.) it did carry 500 pound bomb, but normally a 250 pound bomb was used.*

T


----------



## fubar57 (Apr 28, 2020)

Probably sketchy at best as I think most F models had 12 exhaust stubs. From the Czech book Monographie 1 "Bell P-39 Airacobra" by Jacek Tomalik - AJ Press 2000






​EDIT: added translation - aircraft serial number 41-7246 with additional tank with volume 110 US gal. (416 dm³) and atypical exhaust pipes "fish tail"

Reactions: Informative Informative:
2 | Like List reactions


----------



## Shortround6 (Apr 28, 2020)

One does wonder about the ground clearance of such a tank on rough airstrips. A more cylindrical tank would cause less worry.


----------



## P-39 Expert (Apr 28, 2020)

fubar57 said:


> Probably sketchy at best as I think most F models had 12 exhaust stubs. From the Czech book Monographie 1 "Bell P-39 Airacobra" by Jacek Tomalik - AJ Press 2000
> 
> View attachment 579205
> 
> ...


Thanks.


----------



## buffnut453 (Apr 28, 2020)

Shortround6 said:


> And just how many missions did the 8th AIr Force fly to Berlin in the fall of 1942?
> 
> Main target was German infrastructure/manufacturing plants.
> 
> ...



Entirely agree...although even the German infrastructure/manufacturing plants weren't attacked until 27 January 1943. Prior to that, 8th AF operations were all against targets in occupied Europe rather than Germany itself.

Reactions: Agree Agree:
2 | Like List reactions


----------



## drgondog (Apr 28, 2020)

fubar57 said:


> Probably sketchy at best as I think most F models had 12 exhaust stubs. From the Czech book Monographie 1 "Bell P-39 Airacobra" by Jacek Tomalik - AJ Press 2000
> 
> View attachment 579205
> 
> ...




That looks like a 75 gallon steel tank - US manufacture.


----------



## P-39 Expert (Apr 28, 2020)

drgondog said:


> That looks like a 75 gallon steel tank - US manufacture.


A little too big for a 75 gallon tank. 75 and 110gal tanks were similarly shaped so it's hard to tell.


----------



## Admiral Beez (Apr 28, 2020)

GregP said:


> You, me, or anyone else claiming something didn't happen is no proof one way or the other.


But let's circle back to the beginning; who is claiming the XP-39 went 390 mph? That seems the logical place to start, since we can then look into their source material. 

Otherwise.... as Wuzak says...


wuzak said:


> You're looking for proof of something that didn't happen?

Reactions: Agree Agree:
1 | Like List reactions


----------



## P-39 Expert (Apr 28, 2020)

Admiral Beez said:


> But let's circle back to the beginning; who is claiming the XP-39 went 390 mph? That seems the logical place to start, since we can then look into their source material.
> 
> Otherwise.... as Wuzak says...


I don't think it did, maybe we need a vote.


----------



## Shortround6 (Apr 28, 2020)

A few books claim there is no documentation. 

You do have the absence of documentation of any sort of rebuttal/complaint/argument from Bell to the NACA say to the effect "your wind tunnel says 340 mph, our flight test/s says 370-375 mph" let alone 390 mph. 
We are not talking 5-10mph out of 400mph here , we are talking about a 50mph discrepancy. A 10-15mph discrepancy should have been able to be fixed fairly easily. Lower the canopy, fix (or at least improve) the radiator and oil cooler ducts and put some sort of adjustable outlets on the radiator, oil and inter-cooler ducts to limit airflow at high speeds.


----------



## GregP (Apr 28, 2020)

Hi Admiral Beez,

When I look up the XP-39, the 390 mph is reported widely in many places. I didn't make the claim. In my library alone, it is reported by Ray Wagner in American Combat Planes and several others. Personally, I doubt the XP-39 went 390 mph on test flights, but I have no proof of it one way or the other. So, if you want to claim it didn't, the burden of proof is not on me to defend the published 390 mph claim that I didn't originally make, the burden of proof is on you and anyone else who wants to claim it didn't go that fast to actually refute it.

Either you doubt all the figures in these often-quoted references or you are cherry-picking the XP-39 to make a point for some agenda of your own. Making calculations from assumed numbers does not refute it. Who is to say how good your numbers are? You could get a 100% representative scale model in a wind tunnel, make it go 390 mph at 20,000 feet, and then extrapolate the horsepower required to do that, and compare the result with the Allison V-1710 installed or something similar.

Failing that, you are just like me, a person who doubts it went 390 mph but has no proof of same. To me, that seems like a lot of effort to lay to rest a claim made for ONE airplane that never saw combat. There were no other P-39 airframes that had the turbocharger system installed. I am unwilling to invest even $1 to refute a claim for one prototype airplane when there is no point in doing so. It is not particularly important to me or anyone else in here because it has no bearing on WWII since the turbocharged P-39 was not ever produced. In fact, it didn't even survive in turbocharged form; the XP-39 flew as the XP-39B without a turbocharger system installed. I like the unique looks of the P-39, but am not really a huge fan of the P-39 in any guise. I actually get to see the occasional P-63 in a Planes of Fame airshow, but I have only seen a P-39 fly twice. It was good to see one fly, but I am still not a huge fan of the type, likely due to early childhood impression that it wasn't very good. In point of fact, it WAS quite good below 12,000 - 15,000 feet. It just wasn't very good as a fighter above the mid-teens.

Good luck in your quest to find the truth. I have only seen published support for the 390 mph claim in my time of some interest in WWII planes, which is around half a century. I have seen the claim questioned in here, even fairly well questioned. But nothing that proves it never happened to me. So, while I am firmly in the corner of the people who doubt the 390 mph claim for the XP-39, I also do not have proof of it. Inserting a picture and saying, "just look at it, it could not go that fast!" doesn't cut it. Simply stated, I want proof it didn't go that fast because there are published claims it DID go that fast. Refuting them beyond a doubt goes WAY beyond someone saying it didn't happen because they say so.

Generally, I solve the proof problem by not bringing up the XP-39 speed claim in casual conversation. In my lifetime, including almost 15 years as a volunteer at the Planes of Fame Museum where we DO talk about WWII fighter planes often, nobody has ever brought up the 390 mph claim out of the blue. Not discussing it means that, for me, it has never come up before anywhere but in this forum. It isn't a problem I need to solve. But I would love to see it laid to rest with some proof that I can point to and say, "There, that proves it!". Until then, I doubt the 390 mph claim, but I cannot state exactly how fast it went from any personal knowledge.

Reactions: Like Like:
2 | Old Old:
1 | Like List reactions


----------



## Reluctant Poster (Apr 28, 2020)

We have now entered the realm of philosophy. This discussion reminds me of Bertram Russel's teapot.
Russell's Teapot - RationalWiki 
Which in turn reminds me of Monty Pythons philosophers soccer match

Reactions: Bacon Bacon:
1 | Like Like:
1 | Agree Agree:
1 | Like List reactions


----------



## Shortround6 (Apr 28, 2020)

If you go back to books/magazines/newsreels published in WW II (especially in the first few years) you can find all sorts of quotes or references to things like 400mph P-40s (and the 700mph dive speeds) which wound up repeated in a number of early post war books. Even William Green has had a number of his "facts" questioned and corrected over the years. Like the 109Ks with a pair of 15mm MG 151s in the cowl. Which has been repeated in other books by other authors and on may internet sites. 
Also the number of "nicknames" that Axis troops were "supposed" to have called Allied aircraft because they were so terrified of them has been shown to be pretty much propaganda. 

Bell lied about how fast the P-39 was to get French and British contracts. They had to specially modify a plane to get through an acceptance test. Why is it so hard to believe that somebody at Bell put out the 390mph figure as advertising/propaganda? 

We have this chart:
http://www.wwiiaircraftperformance.org/P-39/P-39C_Chart-Bell_Aircraft-1400.jpg 

which is dated 10-29-39 and "checked" on 2-7-40 and while it does say "plotted from tables" it does NOT say "estimated." 
The XP-39 did not makes it's first flight until 11-25-39 (nearly a month after the date on the chart?) and that was a 15 minute flight. 

The chart is supposed to be for a P-39C but a P-39C won't fly until Jan 1941. So obviously that chart was nothing but estimates. 

Many of those authors were just going by common knowledge or what others had written. It was the best information they had at the time. 

as for 



GregP said:


> Inserting a picture and saying, "just look at it, it could not go that fast!" doesn't cut it.



go back and read the posts. Claiming that the P-39N went XXX speed using about the same amount of power and therefore PROVES the XP-39 could have done it doesn't cut it either as the two planes had very different drag numbers as a result of their different configurations, 

Part of the contention is not about one airplane that never saw combat, it is about the often made claim that the NACA and AIr Corp Generals/officers _Ruined _the P-39 and the US could have had a much better fighter and done much better against the Germans and Japanese in 1942/43 if it wasn't for the stupidity of the NACA and those Air Corp officers.

Reactions: Like Like:
2 | Like List reactions


----------



## GregP (Apr 28, 2020)

Once again, you completely miss my point. I don't care either way if the XP-39 went 390 mph or not. It did not affect WWII and it was only one airplane. A calculated plot is an estimate of performance, not a test, and the P-39C is not the XP-39.

It is NOT hard for me to believe the XP-39 never went 390 mph. In fact, I believe it did not. What I lack is any proof either way. I have never seen an actual plot of the XP-39 flight performance speed envelope, but I DO have several references that make that claim.

But I will not jump on the bandwagon of saying something and ignoring the scientific method. To follow the scientific method, you ask a question, do background research, form a hypothesis, test your hypothesis with an experiment, analyze your data and draw a conclusion, and communicate your results. By "test your hypotheis," I mean disprove it. The statement might be, "The XP-39 went 390 mph in 1939." Can you disprove it? I can't. The method is NOT to state what you want and show some data supporting it. The method is to state something you don't believe and disprove it.

So far, all I see are people making a hypothesis statement that the XP-39 did not go 390 mph. I don't see anything resembling a test of the hypothesis and I especially don't see any analysis of the results or communicated results. All I see is speculation. Good in itself, but hardly conclusive.

And this ain't philosophy. We are talking about hard engineering facts. An opinion won't change what actually happened. It is difficult to find original XP-39 data either way, but very easy to find data that support lower speeds for non-turbocharged airframes that weren't the XP-39. I've never seen a production test of an actual P-39 that exceeded 400 mph in level flight, but I've seen NO DATA about actual XP-39 test flights. I HAVE seen some NACA wind tunnel reports on the XP-39 that may or may not be in the same configuration as test flown by Bell.

Reactions: Like Like:
1 | Old Old:
1 | Like List reactions


----------



## Peter Gunn (Apr 28, 2020)

"_And I still don't consider escort missions to Holland, Belgium and a sliver of France to be meaningful. Not when your main target is Berlin._"

Uh... since when is any combat mission, especially in the formative period for a fledgling giant (i.e. 8th AAF) NOT considered meaningful?

Asking for a friend.

Reactions: Bacon Bacon:
1 | Like Like:
1 | Agree Agree:
2 | Like List reactions


----------



## DerAdlerIstGelandet (Apr 28, 2020)

P-39 Expert said:


> And I still don't consider escort missions to Holland, Belgium and a sliver of France to be meaningful. Not when your main target is Berlin.



What? Huh? Seriously?

So why is Berlin the only meaningful target? You do realize that the majority of strategic targets are not in Berlin right? You’ve got factories, munitions plants, ship yards, strategic materials, rail yards, stock yards, etc. from the French Coast to Berlin and back. I guess we should not have been bombing those meaningless ball bearing factories and steel mills hundreds of kilometers from Berlin. All those boys died on meaningless missions.

Sorry, but good thing you are an armchair general like the rest of us. Otherwise we would still be bombing Berlin today, while they keep building tanks, planes and munitions in France, Belgium, Netherlands, Stuttgart, Wilhelmshafen, Aachen, Franfkfurt, etc.

Reactions: Like Like:
1 | Agree Agree:
1 | Like List reactions


----------



## drgondog (Apr 28, 2020)

P-39 Expert said:


> A little too big for a 75 gallon tank. 75 and 110gal tanks were similarly shaped so it's hard to tell.



Not really - the 110 was about 40% longer and less 'fat' with respect to length. That said, the P-39 was only cleared structurally for a 500 pound bomb - with sway braces.


----------



## drgondog (Apr 28, 2020)

75 gal US Steel tank, then two 108 gal impregnated paper British tanks ~~ November/December 1943 for the P-47 shots.
The P-51B w/75 gal tanks used the same tanks as the P-47D tanks - combat tanks from US manufacture. The 355th Tank Farm gives a better perspective of rounded cigar vs tear drop design between 75gal and 108/110 gal tanks.

Reactions: Informative Informative:
1 | Like List reactions


----------



## fubar57 (Apr 28, 2020)

How much does a 110 gallon drop tank weigh? I have gas weighing in at 6lbs per gallon so a 110 gallon drop tank would be 660lbs plus the weight of the tank. A little over the design of the P-39


----------



## pbehn (Apr 28, 2020)

P-39 Expert said:


> And I still don't consider escort missions to Holland, Belgium and a sliver of France to be meaningful. Not when your main target is Berlin.


Holland and Belgium contained the Kammhuber line and airfields that protected the industrial area that is little more than a stones throw over the border.

Reactions: Like Like:
1 | Winner Winner:
1 | Like List reactions


----------



## drgondog (Apr 28, 2020)

fubar57 said:


> How much does a 110 gallon drop tank weigh? I have gas weighing in at 6lbs per gallon so a 110 gallon drop tank would be 660lbs plus the weight of the tank. A little over the design of the P-39



60 pounds for 75, 90 for 108/110 and 115 for the 160 gal tank. so the 75 gallon tank and fuel is 525 pounds (US) and the 110 weighs 775 pounds.

Reactions: Like Like:
1 | Informative Informative:
1 | Like List reactions


----------



## Reluctant Poster (Apr 28, 2020)

pbehn said:


> Holland and Belgium contained the Kammhuber line and airfields that protected the industrial area that is little more than a stones throw over the border.
> View attachment 579237


Short rounds point is that the goal wasn’t to bomb Holland into submission it was to bomb Germany. A fighter that can only escort to the edge of Germany is inadequate, as was proved in reality. The Spitfire is constantly castigated for this failing.

Reactions: Agree Agree:
1 | Like List reactions


----------



## pbehn (Apr 28, 2020)

Reluctant Poster said:


> Short rounds point is that the goal wasn’t to bomb Holland into submission it was to bomb Germany. A fighter that can only escort to the edge of Germany is inadequate, as was proved in reality. The Spitfire is constantly castigated for this failing.


Well yes, but you do what you can with what you've got, the Spitfire Mk IX was only castigated because of its range when aircraft with similar performance and longer range were available, up to that point it was used to B-17s on raids. If you take airforces out of it, there was a learning process by all involved, improving bombers and fighters, range and load and defence and function. Even if you just want to bomb Germany you have to drive air defence out of North France Belgium and Netherlands to maximise the number of routes into Germany, but as per my previous post the Ruhr area was a centre of German heavy industry and actually has more people than Berlin.


----------



## wuzak (Apr 28, 2020)

GregP said:


> When I look up the XP-39, the 390 mph is reported widely in many places. I didn't make the claim. In my library alone, it is reported by Ray Wagner in American Combat Planes and several others. Personally, I doubt the XP-39 went 390 mph on test flights, but I have no proof of it one way or the other. So, if you want to claim it didn't, the burden of proof is not on me to defend the published 390 mph claim that I didn't originally make, the burden of proof is on you and anyone else who wants to claim it didn't go that fast to actually refute it.





GregP said:


> Good luck in your quest to find the truth. I have only seen published support for the 390 mph claim in my time of some interest in WWII planes, which is around half a century. I have seen the claim questioned in here, even fairly well questioned. But nothing that proves it never happened to me. So, while I am firmly in the corner of the people who doubt the 390 mph claim for the XP-39, I also do not have proof of it. Inserting a picture and saying, "just look at it, it could not go that fast!" doesn't cut it. Simply stated, I want proof it didn't go that fast because there are published claims it DID go that fast. Refuting them beyond a doubt goes WAY beyond someone saying it didn't happen because they say so.



How do you prove that something _*didn't*_ happen?

If you have documentation of test flights, or such, you can prove that something *did* happen. What documents spell out that something *didn't* happen?

It is impossible to prove that the XP-39 *didn't* go 390mph. It is only possible to prove that it *did*, but no direct evidence exists of that fact, as far as we are aware. 

It is reasonable to conclude that the XP-39 did not go 390mph based on the lack of evidence that it did, and that the airframe was taken to NACA for remedial aerodynamic work a few weeks after first flight - the USAAC probably would not authorize that for a 390mph aircraft in 1939.


----------



## Shortround6 (Apr 28, 2020)

GregP said:


> To follow the scientific method, you ask a question, do background research, form a hypothesis, test your hypothesis with an experiment, analyze your data and draw a conclusion, and communicate your results. By "test your hypotheis," I mean disprove it. The statement might be, "The XP-39 went 390 mph in 1939."



Well, lets see, we have.

1, no test report the XP-39 did fly 390mph. 
2. reports of continued oil overheating and/or high temperatures causing at least one flight to be cut short.
3, At least one report of high coolant temperatures.
4, reports or accounts of modifications done to oil and radiator ducts. Which did not solve the problem
5, accounts of how the AAC wanted a new drive shaft installed in the plane because of vibration problems or worries if the engine misfired. Until new drive shaft was fitted engine rpm was restricted to either 2600or 2700rpm. The New drive shaft was not fitted until after the plane went to Langley. No full power flights?
6 time available.
a, first flight April 6th, 15 minutes.
b 2nd flight April 7th cut short due to oil temp
c. 3rd and 4th flights on April 22 total 47 minutes.
d 5th flight April 23, Nose wheel fails after manual lowering of landing gear, 1 hour 40 minutes total flying time in 5 flights. 
e. accounts do not say what flying or tests were done in May of 1939. could have been some. 
f. Plane is delivered to Langley on June 6th. After arrangements made at the end of April. 
7, Langley claimed that the oil cooling problem was resolved or minimized during initial flight tests by using a higher drag duct than originally fitted. 

So, *if *the XP-39 did do 390mph or anywhere near to it it had to be done in May, (none of the April flights were long enough to get to 20,000ft, do a high speed run and get back down on the ground again.) with a high drag oil cooler duct, a radiator that had problems (like at 350mph the radiator was supposed to have 16,900 cubic ft of air going through but only 10,250 cu ft was needed to cool the engine) and the engine was limited to 90% or less of rated rpm, unless the pilot disobeyed instructions. 

I can't_ prove_ the XP-39 didn't hit 390mph but the chances of it are pretty slim. And if it hit 390 mph with all those problems it should have been a real rocket once they got fixed.

Reactions: Like Like:
1 | Agree Agree:
1 | Winner Winner:
1 | Like List reactions


----------



## gjs238 (Apr 28, 2020)



Reactions: Funny Funny:
3 | Winner Winner:
2 | Like List reactions


----------



## GregP (Apr 28, 2020)

You too. Cheers.


----------



## GregP (Apr 28, 2020)

Thanks, Shortround. You summed it up nicely. The claim is that the Bell XP-39 hit 390 mph at 20,000 feet in 1939 in the original test configuration.

We can't prove it happened and we can't prove it didn't happen at this time. It seems unlikely to me that it did, but neither you nor I can say for sure as you say plainly above. There ARE reports it did exactly that originate from what I would say are widely-accepted sources for other data as well as suppositions that it didn't from other widely-accepted sources.

In summary, as stated many times before: It can't be proven either way at this point, but the preponderance of evidence points in the direction of about 375 mph at best and perhaps 357 mph at worst at 20,000 feet in the configuration in which it was supposedly flown in 1939, before it went to the NACA wind tunnel.

That's about as certain as I can say it, and it seems like a reasonable summary to me. Perhaps you think you know better with some certainty? That would require evidence (proof) of same which I have been unable to locate. If you have it, for heaven's sake present it. I'd love to see it. If you don't then, as much as it seems unlikely, we basically agree that it LIKELY didn't go that fast.

If there WAS a test flight (seems like there was to me), there IS a report somewhere on it, assuming it survives in some form. So, it still may surface at some point, maybe not because it is lost. If not, then nobody knows what it says other than speculation.

And it only took 10+ years to come to that. I'd have thought we'd agree on that much in our first exchange on the subject, but it seems like we don't agree on much very often ... or maybe we actually do, and just disagree on the things we go back and forth about, which seems more likely.

Hey admiral Beez,

The original claim I saw came from "American Combat Planes by Ray Wagner. My original copy was dated 1960, but I lost that in a Tornado in Indiana when I was Purdue University in the late 1960's / early 1970's. My current copy is dated 1982 and the list of sources is not all THAT long; some 3 1/2 pages in something like 12-point font.

Since you asked, I looked at Ray Wagner's sources. Among them is "U.S. Army Aircraft (Heavier Than Air) 1908 - 1946 by James C. Fahey, copyright 1946, published by Ships and AIrcraft, P.O. Box 48, Falls Church, Virginia." Library of Congress card number 46-7791.

As luck would have it, I have a pristine copy that I have not looked at for more than 20 years, but I took it out to check on this. On page 33, it lists the Bell XP-39 at 390 mph, aircraft ordered in FY 38, delivered in FY39. It lists the gross weight at 6,204 lbs. and says the Allison was a V-1710-17 of 1,150 HP. It doesn't state an altitude or rpm. Among Mr. Fahey's sources are many U.S. Government agencies including Officers and Personnel of the Technical Data, Still Photo, and other sections of the "The Air Technical Service Command, Wright Field." No single source is mentioned for the XP-39 or any other data. He seems to have about 20 U.S. Government sources and only a few civilian ones.

Perhaps Mr. Fahey started this can of worms based on Wright Field information, I can't say for sure.


----------



## wuzak (Apr 29, 2020)

GregP said:


> In summary, as stated many times before: It can't be proven either way at this point, but *the preponderance of evidence points in the direction of about 375 mph* at best and perhaps 357 mph at worst at 20,000 feet in the configuration in which it was supposedly flown in 1939, before it went to the NACA wind tunnel.



It does?

What evidence is that?


----------



## wuzak (Apr 29, 2020)

wuzak said:


> It does?
> 
> What evidence is that?



NACA _estimated_ the XP-39 would have a top speed of 340mph @ 20,000ft in its original configuration. Which strongly suggests that the top speed achieved before it went to NACA was less than 340mph.

NACA also _estimated_ that a cleaned up turbocharged XP-39 would have a top speed of 392mph @ 20,000ft. Could this be the source of the XP-39 managing 390mph?

See XP-39 and the Claims


----------



## GregP (Apr 29, 2020)

Enough trolling, Wayne. Read the thread.

It isn't fun anymore.


----------



## Stig1207 (Apr 29, 2020)

Here Wagner writes 365 mph at 20,000 ft ?! 

P-39 by Ray Wagner - Page 1

Reactions: Like Like:
1 | Like List reactions


----------



## nuuumannn (Apr 29, 2020)

P-39 Expert said:


> And I still don't consider escort missions to Holland, Belgium and a sliver of France to be meaningful. Not when your main target is Berlin.



Thank heaven you weren't planning air raids during the war, then. Your tenure as strategic planner would be very short indeed.


----------



## nuuumannn (Apr 29, 2020)

Reluctant Poster said:


> Which in turn reminds me of Monty Pythons philosophers soccer match



Where would the world be without Monty Python to put it all into context?


----------



## Reluctant Poster (Apr 29, 2020)

pbehn said:


> Well yes, but you do what you can with what you've got, the Spitfire Mk IX was only castigated because of its range when aircraft with similar performance and longer range were available, up to that point it was used to B-17s on raids. If you take airforces out of it, there was a learning process by all involved, improving bombers and fighters, range and load and defence and function. Even if you just want to bomb Germany you have to drive air defence out of North France Belgium and Netherlands to maximise the number of routes into Germany, but as per my previous post the Ruhr area was a centre of German heavy industry and actually has more people than Berlin.


Actually the 8th Airforce thought just the opposite. The theory was that the since the defenses were supposedly concentrated near the coast, once they broke through the strong defense the opposition would be much weaker in the interior. This would allow the unescorted bombers to reach the target without prohibitive losses. This theory was tried in the August 1943 with the first Schweinfurt raid. At that point the theory must have seem a bit suspect, but it took a few more catastrophic raids to finally put an end to the unescorted bomber theory.





This is an excerpt from the attached paper

Reactions: Informative Informative:
1 | Like List reactions


----------



## P-39 Expert (Apr 29, 2020)

It's my experience that if you read long enough you can find somebody who made some statement sometime ago that agrees with your position. And some that don't.

And a whole lot of it is hearsay passed down from some sage from way back who isn't around anymore. After a while these hearsay arguments are taken as fact. And a lot of them contradict each other.

Then wwiiaircraftperformance.org somehow materializes in 2006 and now we have the actual govt/military performance tests. Updated through 2015 these are actual test documents from the US, GB, Germany and Japan (no Soviet section?). Now all is revealed. As fact, not some opinion from '42 that may be grounded in fact but then again may not, made by someone who may have an ax to grind, or not. How the hell can we know? No matter, now we have the actual facts from the original tests.

Back to wwiiaircraftperformance.org. I understand the owner/founder is a gentleman named Mike Williams who is a member of this chat board. I have seen his name periodically at the bottom of the page under "Users who are viewing this thread". Now I don't know Mr. Williams personally as apparently some on here do. I had in the past emailed him asking about information on (you guessed it) the P-39 among others. I never got an answer to my emails (no problem, I'm sure Mr. Williams is plenty busy with other duties) but then shortly after the P-39 information began to appear. Thanks so much Mr. Williams. Just a few questions below?

1. The latest additions to your excellent site are from 2015. Will there be more posts? Is there more information waiting to be put on the site? 
2. Regarding specifically the P-39N, your performance tests offer information that I as a voracious reader for the last 65 years had not seen before. Previously all I ever saw regarding the N was "Top speed 399mph. Service ceiling 38500ft". Just asking, but are you the only person with this information? Do you have the only copy of those specific tests? Only reason I am asking is your site is the only place I have ever seen that information. And, yes, do you have any more information on the P-39?

Mr. Williams, thanks for you site and all the valuable (and until now somewhat secret) information it provides. Hope I am not invading your privacy with these questions. 

Thanks again.

Reactions: Like Like:
2 | Funny Funny:
1 | Like List reactions


----------



## GregP (Apr 29, 2020)

I have to say you hit the nail on the head, P-39 Expert. 

Thank you Mike Williams for coming up with such a great website.

Reactions: Like Like:
1 | Like List reactions


----------



## pbehn (Apr 29, 2020)

Reluctant Poster said:


> Actually the 8th Airforce thought just the opposite. The theory was that the since the defenses were supposedly concentrated near the coast, once they broke through the strong defense the opposition would be much weaker in the interior. This would allow the unescorted bombers to reach the target without prohibitive losses. This theory was tried in the August 1943 with the first Schweinfurt raid. At that point the theory must have seem a bit suspect, but it took a few more catastrophic raids to finally put an end to the unescorted bomber theory.
> View attachment 579310
> 
> 
> This is an excerpt from the attached paper


There were many theories. The bomber will always get through. The bomber box can defend itself. Long range escort was impossible. Long range escort was vital. Bombing can win the war alone. Bombing Germanys ball bearing plants can end the war early. As far as I can see the theory of a "fighter belt" was put forward by someone whose fighters can only reach that fighter belt. Any discussion with RAF recon pilots, with RAF bomber command and look at the Battle of Britain would show it is a convenient fantasy. Any Me110 is an effective fighter against unescorted bombers and Germany obviously had them as night fighters. RAF recon could tell them there were fighters behind any "fighter belt". In Jan 1943 in the famous raid on Goerings radio transmission one Mosquito was shot down south of Berlin. Dowding and Park didnt have a "fighter screen" so why would anyone suppose the Germans had, and why would anyone suppose it wouldnt be moved back out of range of enemy fighters. If you amble into central Germany at 180mph the fighters who met you on the way there have time to land re fuel and re arm and meet you on the way back and fighters from well off the line of the mission can be called into the battle.

Reactions: Agree Agree:
1 | Like List reactions


----------



## Reluctant Poster (Apr 29, 2020)

pbehn said:


> There were many theories. The bomber will always get through. The bomber box can defend itself. Long range escort was impossible. Long range escort was vital. Bombing can win the war alone. Bombing Germanys ball bearing plants can end the war early. As far as I can see the theory of a "fighter belt" was put forward by someone whose fighters can only reach that fighter belt. Any discussion with RAF recon pilots, with RAF bomber command and look at the Battle of Britain would show it is a convenient fantasy. Any Me110 is an effective fighter against unescorted bombers and Germany obviously had them as night fighters. RAF recon could tell them there were fighters behind any "fighter belt". In Jan 1943 in the famous raid on Goerings radio transmission one Mosquito was shot down south of Berlin. Dowding and Park didnt have a "fighter screen" so why would anyone suppose the Germans had, and why would anyone suppose it wouldnt be moved back out of range of enemy fighters. If you amble into central Germany at 180mph the fighters who met you on the way there have time to land re fuel and re arm and meet you on the way back and fighters from well off the line of the mission can be called into the battle.


I would put your original post in the same category.


----------



## pbehn (Apr 29, 2020)

Reluctant Poster said:


> I would put your original post in the same category.


 In what way.


----------



## FLYBOYJ (Apr 29, 2020)

I've skipped around this thread while eating popcorn. Has anyone brought up Mike Williams page on the P-39? 

P-39 Performance Tests


----------



## GregP (Apr 29, 2020)

It has been alluded to but the production P-39s, as you know, are not representative of the XP-39 in either of its forms. 

Thanks for the link above, it always takes me awhile to find the aircraft I want to look up, but it's also well worth the time. Mike surely has a great website.


----------



## FLYBOYJ (Apr 29, 2020)

GregP said:


> It has been alluded to but the production P-39s, as you know, are not representative of the XP-39 in either of its forms.
> 
> Thanks for the link above, it always takes me awhile to find the aircraft I want to look up, but it's also well worth the time. Mike surely has a great website.



There's info on the XP-39B but it's shown that it has put on some weight since April 6, 1939.

Reactions: Like Like:
1 | Like List reactions


----------



## varsity07840 (Apr 29, 2020)

FLYBOYJ said:


> There's info on the XP-39B but it's shown that it has put on some weight since April 6, 1939.



So, we're twelve pages into this topic, talking about the XP-39s top speed, the P-39's external tank capacity and range and the P-39N's performance to a point where minutia has been exhausted. After all that, so what? The P-39 had a dismal record in air combat in AMERICAN service. Woulda coulda shoulda aside, the P-39 was deemed unsuitable for AMERICAN use, which is why it was purchased by the AAF. It wasn't designed as an export fighter for the Russians.

Reactions: Agree Agree:
1 | Like List reactions


----------



## fubar57 (Apr 29, 2020)



Reactions: Bacon Bacon:
2 | Winner Winner:
2 | Like List reactions


----------



## FLYBOYJ (Apr 29, 2020)

varsity07840 said:


> So, we're twelve pages into this topic, talking about the XP-39s top speed, the P-39's external tank capacity and range and the P-39N's performance to a point where minutia has been exhausted. After all that, so what? The P-39 had a dismal record in air combat in AMERICAN service. Woulda coulda shoulda aside, the P-39 was deemed unsuitable for AMERICAN use, which is why it was purchased by the AAF. It wasn't designed as an export fighter for the Russians.


Yup - and it may go into page 13!!


----------



## P-39 Expert (Apr 30, 2020)

GregP said:


> I have to say you hit the nail on the head, P-39 Expert.
> 
> Thank you Mike Williams for coming up with such a great website.


Absolutely. Do you think he will reply to my questions?


----------



## GregP (Apr 30, 2020)

No idea. I'm pretty sure Mike Williams stays busy. At least, his website indicates he spends a lot of time there.

Good luck. I bet if he reads this, he'll answer. But whether or not he reads this thread is a bet I wouldn't care to make since I don't personally know Mike.


----------



## pbehn (Apr 30, 2020)

P-39 Expert said:


> Absolutely. Do you think he will reply to my questions?


How do you propose someone merely called Mike Williams would reply to someone called "P-39 Expert" on the subject of the P-39?

Reactions: Like Like:
1 | Agree Agree:
1 | Funny Funny:
4 | Like List reactions


----------



## Jugman (Apr 30, 2020)

wuzak said:


> NACA _estimated_ the XP-39 would have a top speed of 340mph @ 20,000ft in its original configuration. Which strongly suggests that the top speed achieved before it went to NACA was less than 340mph.
> 
> NACA also _estimated_ that a cleaned up turbocharged XP-39 would have a top speed of 392mph @ 20,000ft. Could this be the source of the XP-39 managing 390mph?
> 
> See XP-39 and the Claims



It's actually worse than that. The NACA full size tunnel had maximum sustained speed of 100 mph. Every NACA estimate I have seen from this time period from aircraft tested in the full size tunnel have been on the optimistic side. Based on what the XP-39B could actually do ( 375 @ 1040hp @ 15,000ft), the estimated performance ( 402 @ 1150hp @ 13,500ft) was ~15-20mph too high. The original and cleaned configurations are probably off by a similar margin

Reactions: Agree Agree:
1 | Like List reactions


----------



## drgondog (May 1, 2020)

Jugman said:


> It's actually worse than that. The NACA full size tunnel had maximum sustained speed of 100 mph. Every NACA estimate I have seen from this time period from aircraft tested in the full size tunnel have been on the optimistic side. Based on what the XP-39B could actually do ( 375 @ 1040hp @ 15,000ft), the estimated performance ( 402 @ 1150hp @ 13,500ft) was ~15-20mph too high. The original and cleaned configurations are probably off by a similar margin



FWIIW - I totally agree. 

If you go back to the images including NACA renditions of original XP-39, the stated CDhs=0.0321 which REALLY high even for Sea Level (P-51B comparable was 0.0208 in Full service condition for 100mph RN of 6.19x10^6 at Langley. The comparable (much cleaner P-63 in the wind tunnel - same series of tests was 0.0221 @RN=6,41x10^6). 

The calculated CDt including Mach No correction at 18,000 feet for *395mph of a P-51B at full throttle, 1480BHP/1091 THP = 0.0195 @ RE=15.31x10x^6 with CLOSED aft scoop. Compare that to the NACA CDhs = 0.0321 for 340mph. Then ask yourself, how would it ever get close to 400mph at 20K with that large Drag coefficient?*

With wide open scoop the CDt for same Mach corrections,The same P-51B at full throttle, the CDt was 0.023 with WIDE Open Scoop (which caused increased Delta Cdt= 0.040)... with some Meredith Cooling drag reduction still occurring. 

This CDt is the entire parasite and form drag of the Mustang x Mach No Correction (~ 1.2 for 395mph at 18000 feet) Plus Induced Drag.. 

Addt'l comments:
The XP-39 drag contributions of both the turbo and oil cooler intakes had to be huge relative to the Mustang.
The XP-39 had no engine exhaust thrust contribution to increase Thp - the P-51B described above yielded 256 pounds of thrust.
There is no indication one way or the other that NACA value "CDhs" included momentum recovery losses for the airframe/wing combo immersed in the prop vortex, but my calculations include such losses as well as the carburetor intake.
With Meredith contributions of closed aft scoop, the net P-51B cooling drag was estimated to be zero, although NAA claimed some net thrust at top speed. The calculated difference between the open scoop top speed and closed scoop top speed horsepower required was 230 pounds of thrust to increase top speed 25mph (393 vs 420) with open scoop.

I spent a lot of time re-creating NA Report 5534 and 8449 Performance calculations methodologies to be able to extract these values from the data gathered in the P-51B-1 Flight Test of May 1943

Reactions: Like Like:
4 | Informative Informative:
4 | Like List reactions


----------



## Reluctant Poster (May 3, 2020)

pbehn said:


> In what way.


You stated they were driving the defenses out of Northern France, Belgium and the Netherlands. I would say that was an excuse for staying within escort range and not doing what they had promised everyone they would do i.e. bombing Germany.
I would also note the USAAF wasn't really bombing the low countries: 36 tons in 1942 and 767 tons in 1943. They didn't start doing that until after D-Day: 12,312 tons in 1944.
They were bombing France: 1,624 tons in 1942 and 14,237 in 1943 but much of that was directed against the U Boat pens farther south.


----------



## pbehn (May 3, 2020)

Reluctant Poster said:


> You stated they were driving the defenses out of Northern France, Belgium and the Netherlands. I would say that was an excuse for staying within escort range and not doing what they had promised everyone they would do i.e. bombing Germany.
> I would also note the USAAF wasn't really bombing the low countries: 36 tons in 1942 and 767 tons in 1943. They didn't start doing that until after D-Day: 12,312 tons in 1944.
> They were bombing France: 1,624 tons in 1942 and 14,237 in 1943 but much of that was directed against the U Boat pens farther south.


Some information on Luftwaffe airfields in Netherlands and Belgium. Which also details attacks on them. They were routinely attacked when in service especially during and after Big Week. It is not true that their "job" was to bomb Germany, it was to win the war, and immediately before D-Day that involved destroying as much of the LW as possible and prepare for D-Day itself. This involved bombing targets in the landing area and also distraction bombing elsewhere to draw attention away from Normandy.

http://www.ww2.dk/Airfields - Netherlands.pdf
http://www.ww2.dk/Airfields - Belgium and Luxembourg.pdf
For example Schipol my bold.
Schiphol attacked by Allied aircraft many times right from May 1940. 20 Jun 40: bombed – 1 x Ju 52 from I./KG z.b.V. 172 badly damaged on the ground. 23 Jun 40: bombed – 1 x Ju 52 from I./KG z.b.V. 172 destroyed on the ground. 10 Aug 40: bombed – 1 x He 111H from KGr. 126 damaged on the ground. 3 *Oct 43: air attack by 9th AAF medium bombers – *2 x Me 410 A-1s from 14./KG 2 and 2 x He 111Hs from Wetterflugstelle Holland and a Klemm Kl 35 from Luftgaukdo. Holland bombed on the ground at Amsterdam-Schipol airfield during an Allied air attack and destroyed (1) or damaged (2). Additionally, hangars, buildings on the SE boundary and the West dispersal were all hit. *3 Nov 43: bombed *– the very large hardstand apron in front of the central hangars on the SE boundary heavily cratered. *13 Dec 43: in a decisive blow against Schiphol that all but eliminated it from the war,* 208 B-26 Marauders from IX Bomber Command dropped 787 1,000-lb. bombs on the airfield - 2 x Bf 109Gs from II./JG 3, 4 x Me 410 A-1s from II./KG 2 and 14./KG 2 plus 1 x He 111 H3 from Wetterflugstelle Holland destroyed (4) or damaged (3) on the ground. Hangars, repair shops, aircraft shelters, runways and taxiways received heavy damage.

Reactions: Informative Informative:
1 | Like List reactions


----------



## Aeroweanie (Jan 23, 2021)

After years of lurking on this site, its time for me to go public. I haven't read all 13 pages of this thread, so I apologize if I'm going over ground that has already been covered.

In 2000, several years after working with with Birch Matthews on Cobra!, I published a SAE paper on the P-39 and P-63. In this paper, which is attached, I delved into the technical side of these aircraft in deeper detail. Now, 20 years later, I have resurrected and expanded on this paper for a presentation that I'll be giving to the Phoenix chapter of the AAHS on February 17th. I'll upload slides when they are finalized. I welcome feedback.

Reactions: Bacon Bacon:
2 | Like Like:
3 | Informative Informative:
2 | Like List reactions


----------



## fubar57 (Jan 23, 2021)



Reactions: Funny Funny:
2 | Like List reactions


----------



## Snautzer01 (Jan 23, 2021)

pbehn said:


> Some information on Luftwaffe airfields in Netherlands and Belgium. Which also details attacks on them. They were routinely attacked when in service especially during and after Big Week. It is not true that their "job" was to bomb Germany, it was to win the war, and immediately before D-Day that involved destroying as much of the LW as possible and prepare for D-Day itself. This involved bombing targets in the landing area and also distraction bombing elsewhere to draw attention away from Normandy.
> 
> http://www.ww2.dk/Airfields - Netherlands.pdf
> http://www.ww2.dk/Airfields - Belgium and Luxembourg.pdf
> ...



Schiphol is the name of the airfield. Still is a mayor one in the eu.


----------



## pbehn (Jan 23, 2021)

Snautzer01 said:


> Schiphol is the name of the airfield. Still is a mayor one in the eu.


I know, after working in Germany for years taking the Hanover Schiphol Teesside flight every other Friday the bar staff in the upstairs bar all knew me by name lol.


----------



## tomo pauk (Jan 23, 2021)

Aeroweanie said:


> After years of lurking on this site, its time for me to go public. I haven't read all 13 pages of this thread, so I apologize if I'm going over ground that has already been covered.
> 
> In 2000, several years after working with with Birch Matthews on Cobra!, I published a SAE paper on the P-39 and P-63. In this paper, which is attached, I delved into the technical side of these aircraft in deeper detail. Now, 20 years later, I have resurrected and expanded on this paper for a presentation that I'll be giving to the Phoenix chapter of the AAHS on February 17th. I'll upload slides when they are finalized. I welcome feedback.



Thank you for sharing that here


----------



## Glider (Jan 23, 2021)

P-39 Expert said:


> Absolutely. Do you think he will reply to my questions?


You might try summarising the questions you would like responses to. Personally I admit to being totally confused as to exactly what is supposed to be outstanding. 
A lot of postings are made, positions stated but questions not so much


----------



## Koopernic (Jan 24, 2021)

Aeroweanie said:


> After years of lurking on this site, its time for me to go public. I haven't read all 13 pages of this thread, so I apologize if I'm going over ground that has already been covered.
> 
> In 2000, several years after working with with Birch Matthews on Cobra!, I published a SAE paper on the P-39 and P-63. In this paper, which is attached, I delved into the technical side of these aircraft in deeper detail. Now, 20 years later, I have resurrected and expanded on this paper for a presentation that I'll be giving to the Phoenix chapter of the AAHS on February 17th. I'll upload slides when they are finalized. I welcome feedback.



Hope you're not vegetarian like my wife because I gave you Bacon. Has there ever been an analysis of what P-39 performance would have been like with say a Merlin XX (two stage Merlin used in the latter Hawker Hurricane to keep it competitive?) The P40F received this engine.


----------



## wuzak (Jan 24, 2021)

Koopernic said:


> Has there ever been an analysis of what P-39 performance would have been like with say a Merlin XX (*two stage* Merlin used in the latter Hawker Hurricane to keep it competitive?) The P40F received this engine.



Two speed.

I'm not sure where the main problem with putting the Merlin into the P-39 would be.

Some of the problems include:
Updraft carburettor would not fit - would have to be changed for an updraft carby.
The supercharger casing may be too big to fit inside the engine bay of the fuselage.
Nose case would have to be modified to suit a remote gearbox - the rear section of the nose case of the Merlin was in unit with the crankcase.
The Merlin needed more cooling than the contemporary V-1710 - the P-39 was already marginal with cooling, from what I understand.
The Merlin XX was about 100lb heavier than the single stage V-1710. May need more ballast up front.

The Merlin was shorter than the V-1710, so that is a positive.

Reactions: Like Like:
1 | Agree Agree:
1 | Like List reactions


----------



## FowellBox (Jan 24, 2021)

Quote: Updraft carburettor would not fit - would have to be changed for an updraft carby. Endquote.
I assume a typo?
Brian


----------



## Snautzer01 (Jan 24, 2021)

pbehn said:


> I know, after working in Germany for years taking the Hanover Schiphol Teesside flight every other Friday the bar staff in the upstairs bar all knew me by name lol.


Ok you mis typed it a few times in a few post back.


----------



## wuzak (Jan 24, 2021)

FowellBox said:


> Quote: Updraft carburettor would not fit - would have to be changed for an updraft carby. Endquote.
> I assume a typo?
> Brian



Oops, yes. Would need a downdraft carby.


----------



## P-39 Expert (Jan 24, 2021)

wuzak said:


> Two speed.
> 
> I'm not sure where the main problem with putting the Merlin into the P-39 would be.
> 
> ...


Also mounts were different on the Allison and Merlin.


----------



## Koopernic (Jan 24, 2021)

I recall reading the memoirs of a Luftwaffe Me 109G pilot who recalls an low altitude engagement with what the Germans thought was P51 over Italy but turned out to be P39. Several aircraft were lost on both sides. 

If the P39 had of been given better engines and if it had of been retired when the P63 Kingcobra entered service in October 1943 it might have a better record. The iconinc P51B Mustang didn’t start flying missions till December 1943 meaning the P51A with its altitude limited Allison was in service.

Reactions: Like Like:
1 | Like List reactions


----------



## drgondog (Jan 25, 2021)

Koopernic said:


> Hope you're not vegetarian like my wife because I gave you Bacon. Has there ever been an analysis of what P-39 performance would have been like with say a Merlin XX (two stage Merlin used in the latter Hawker Hurricane to keep it competitive?) The P40F received this engine.


Practically speaking, the opportunity to even 'try' to install a Merlin 61 in the P-63 would have been quashed by Materiel Command based on the Priority assigned to NAA for the Mustang. That is why the P-38 was never even granted a 'try' when Cass Hough and Ben Kelsey floated the project from 8th AF Service Command in 1944.

Additionally, there was no AAF Mission for which a P-63 with fully functional Merlin 61/66 would have been superior to either P-51B/D or P-51F. The latter, with far superior performance, armament (4x20mm in interceptor role) and internal fuel for range would have been far superior to P-63 in perhaps every meaningful metric as an interceptor and very suitable for medium to long range escort (similar to P-38J pre-LE fuel cells) - and it was killed in favor of P-51H

Reactions: Like Like:
2 | Like List reactions


----------



## wuzak (Jan 25, 2021)

drgondog said:


> Practically speaking, the opportunity to even 'try' to install a Merlin 61 in the P-63 would have been quashed by Materiel Command based on the Priority assigned to NAA for the Mustang. That is why the P-38 was never even granted a 'try' when Cass Hough and Ben Kelsey floated the project from 8th AF Service Command in 1944.



The premise was the Merlin XX into the P-39. Which would mean taking from the P-40F/L program, or from supply to the UK/Canada (Hurricane, Lancaster, Mosquito, etc.).

Probably unlikely to happen as well.

Reactions: Agree Agree:
2 | Like List reactions


----------



## Shortround6 (Jan 25, 2021)

The questions are when and why.
The P-40F prototype flew in July of 1941(?). Production started in Jan 1942. 
The US was to get 3000 engines from the 9000 engine contract placed with Packard and had to use them for something. Installation in P-40 required no changes to the engine itself. 

You could modify the Merlin to fit the P-39 set up but only at a cost (engineering time and testing taking how long?) 
In 1942 Bell made 1932 P-39s, Curtiss built 3854 P-40s. How many fewer P-39s do you want in 1942 while Bell adapts the P-39 to the Merlin? (like new cooling systems/bigger air ducts?)

While it is quite true that the P-51B didn't go into combat until Dec 1943 the first order for the P-51B (400 planes) was placed on Aug 26th 1942, This is before the First flight is made of an A-36. On Oct 6th 1942 North American Dallas gets a contract for 1350 P-51Cs. 

Using the Merlin XX in the P-39 is only going to shorten the range, maybe a little, maybe a lot. The Merlin wasn't quite as fuel effectint as the Allison (single digit percentage) but if you have several hundred more horsepower available at higher altitudes to fight with and if you use that power to have to use fuel to make that higher power. In a low altitude fight there may be little to choose in fuel consumption for our 15 minute standard but at high altitude the Merlin might be going through 20-25% more fuel per minute? I haven't looked it up It may be even more.
You can't put more fuel in the P-39 without extreme difficulty and even more weight. Bigger drop tank doesn't get you home from the fight. 
P-40 held almost 20% more fuel than the P-39. 

A Merlin XX powered P-39 would have performed better at high altitude than the standard P-39 (especially the 8.80 supercharger gear models) but it might not show up until late 1942. 
P-40Fs didn't show up in combat until the Fall of 1942? But it might not have performed any better at low altitude or even performed quite as well. See P-40E & K vs P-40F. 

If it costs both engine production and airframe production would it have been worth it?

Reactions: Like Like:
2 | Agree Agree:
1 | Like List reactions


----------



## P-39 Expert (Jan 25, 2021)

Shortround6 said:


> The questions are when and why.
> The P-40F prototype flew in July of 1941(?). Production started in Jan 1942.
> The US was to get 3000 engines from the 9000 engine contract placed with Packard and had to use them for something. Installation in P-40 required no changes to the engine itself.
> 
> ...


----------



## Koopernic (Jan 26, 2021)

The P-39 is often compared as wanting in comparison to the Me 109F/G and A6M Zero's. Both these aircraft had either variable speed or two speed superchargers. The Hurricane likewise was not considered competitive without a Merlin XX. Maybe the P-39's airframe wasn't as much a problem as a lack of a high altitude engine. It's most famous user, the VVS, tended to operate at low altitude. From an allied point of view perhaps it would have been better to utilise Merlin XX in the P-39 than the Hurricane. The Spitfire is in a league of its own in being competitive with a single stage single speed supercharger.


----------



## P-39 Expert (Jan 26, 2021)

The vast majority of P-39s operated by the VVS were the later M/N/Q models with the uprated -85 engine with 9.6 supercharger gears. Their standard combat formation was the "Kuban Stairs" or "Flying Bookshelves" advocated by Alexander Pokryshkin. A normal 12 plane squadron flew a four plane flight at 5000meters (16500'), another flight at 6000m (19800') and the third at 7000m (23100') angled upsun. Not exactly low altitude, and the Luftwaffe fighters certainly had no altitude restrictions placed on them. Admittedly there were no high altitude B-17s or B-24s to escort/intercept, but not exactly down in the mud either.


----------



## tyrodtom (Jan 26, 2021)

P-39 Expert said:


> The vast majority of P-39s operated by the VVS were the later M/N/Q models with the uprated -85 engine with 9.6 supercharger gears. Their standard combat formation was the "Kuban Stairs" or "Flying Bookshelves" advocated by Alexander Pokryshkin. A normal 12 plane squadron flew a four plane flight at 5000meters (16500'), another flight at 6000m (19800') and the third at 7000m (23100') angled upsun. Not exactly low altitude, and the Luftwaffe fighters certainly had no altitude restrictions placed on them. Admittedly there were no high altitude B-17s or B-24s to escort/intercept, but not exactly down in the mud either.



You seem to forget why the aircraft were flying in that 3 tiered formation.
Each tier was there to provide protection for the aircraft under it.
If the aircraft in the formation below got into trouble , a aircraft from above could use the higher altitude to trade for airspeed , and enter the combat with a higher speed.
And the lowest tier was there to protect the aircraft at even lower levels , the IL-2s, Pe-2s, etc. were doing the real work. 

This a standard tactic dating to the first world war, you patrol at a higher altitude, you only fight there when someone comes in ever higher and forces you to fight there. 
And almost any combat maneuvering is going to result in losing altitude, so you always want to start with a altitude advantage.

Reactions: Like Like:
1 | Agree Agree:
1 | Like List reactions


----------



## P-39 Expert (Jan 27, 2021)

tyrodtom said:


> You seem to forget why the aircraft were flying in that 3 tiered formation.
> Each tier was there to provide protection for the aircraft under it.
> If the aircraft in the formation below got into trouble , a aircraft from above could use the higher altitude to trade for airspeed , and enter the combat with a higher speed.
> And the lowest tier was there to protect the aircraft at even lower levels , the IL-2s, Pe-2s, etc. were doing the real work.
> ...


I was explaining why the eastern front was not as much of a low altitude war as many seem to think. What is your point?


----------



## Glider (Jan 27, 2021)

My understanding is that because the escort is stepped up to cover lower flying aircraft, doesn't mean that the emphasis of the fighting is at a high or even medium level. The Russian airforce wasn't trained or equipped for instance to fight at at 20-30,000 ft. 

It doesn't mean that they couldn't, but they didn't, and their planes tended understandably, to reflect that tactical approach of low level fighting.


----------



## tyrodtom (Jan 27, 2021)

P-39 Expert said:


> I was explaining why the eastern front was not as much of a low altitude war as many seem to think. What is your point?


You seem to think that their patrol height is the altitude they fight at.

In your example you've got 12 aircraft out there, but only 4 are performing the primary mission, protecting the ground attack aircraft.
The other 8 are there to protect the protectors.
The aircraft at 7000 meters certainly can't help the ground attack aircraft, they'd have to really look hard to even id camouflaged aircraft against ground cover from 4 miles up, their mission is to protect the P=39s in the lower groups.

If you don't see my point, it's because you don't want to accept that anyone else's view might have some value.

Reactions: Like Like:
1 | Agree Agree:
1 | Like List reactions


----------



## Koopernic (Jan 27, 2021)

Shortround6 said:


> The questions are when and why.
> The P-40F prototype flew in July of 1941(?). Production started in Jan 1942.
> The US was to get 3000 engines from the 9000 engine contract placed with Packard and had to use them for something. Installation in P-40 required no changes to the engine itself.
> 
> ...



The thing about the Merlin XX is it leads to the 1600 hp Merlin 24 which was way ahead of any single stage Allison.


----------



## P-39 Expert (Jan 27, 2021)

tyrodtom said:


> You seem to think that their patrol height is the altitude they fight at.
> 
> In your example you've got 12 aircraft out there, but only 4 are performing the primary mission, protecting the ground attack aircraft.
> The other 8 are there to protect the protectors.
> ...


Seems to me that all 12 planes in the squadron are protecting the ground attack aircraft. The Luftwaffe is not going to fly at low altitude just because some historian says the Eastern front was a low altitude war. I accept everyone's view on this forum.


----------



## DerAdlerIstGelandet (Jan 27, 2021)

P-39 Expert said:


> I accept everyone's view on this forum.

Reactions: Agree Agree:
1 | Funny Funny:
1 | Like List reactions


----------



## P-39 Expert (Jan 27, 2021)

DerAdlerIstGelandet said:


> View attachment 610394


I said I accepted everyone's view, not that I agreed with everyone's view.

Reactions: Winner Winner:
1 | Like List reactions


----------



## tyrodtom (Jan 27, 2021)

P-39 Expert said:


> Seems to me that all 12 planes in the squadron are protecting the ground attack aircraft. The Luftwaffe is not going to fly at low altitude just because some historian says the Eastern front was a low altitude war. I accept everyone's view on this forum.


If they want to shoot down the IL-2 they have to get close to where it is, and it's the ground attack aircraft that is doing the damage.
Do you really think a pilot flying at 20,000 feet can pick out a camouflaged aircraft flying at ground level ?

Reactions: Agree Agree:
1 | Like List reactions


----------



## GregP (Jan 27, 2021)

About post 272 Koopernic,

The Allison V-1710-75, -77, -89, -91, & -111/113 all had 1600 hp WER. The -75 and -77 were rated at 1600 hp at 27,000 feet WER. The -111/113 were rated at 1600 hp at 28,700 feet. These were P-38 engines. These ratings were at 60.0 in. MAP. They all had 8.10 : 1 supercharger gears.

The -87 was rated at 1,500 hp at 5,400 ft. It was an A-36 engine. This was at 52 in. MAP. It has 7.48 : 1 supercharger gears.

The above had PD-12K7 and K8 carburetors.

The -109, -117, -125, & -129 were rated at 1,750 hp (75 in. MAP), 1,800 hp (76 in. MAP), and 1900 hp (75 in. MAP) for the -125/129s. The -09 and -117 were P-63 engines. Not too sure about the others ... might have been test cell ratings. They had 8.10 : 1 supercharger gears. The -109 had a PT-13E15 carb and the -117 had a PT-13E10 carb. The -125 and -129 had a PD-12K8 carb and the -129 has a PD-12K15 carb.

All of these ratings were at 3,000 rpm and I'm not sure the 70+ in. MAP levels of boost were flown by U.S. forces. Likely they were by the Soviet Union. 
Note there are no P-39 engines in the above. The P-39M (-83) and N (-85) models were rated at 1410 hp at 9,500 ft and 3,000 rpm, 57 in. MAP. They had 9.6 : 1 supercharger gerars. The -83 had a PD-12K2 carburetor and the -85 had a PD-12K6 carburetor.

Reactions: Agree Agree:
1 | Like List reactions


----------



## Shortround6 (Jan 27, 2021)

Spitfires, Hurricanes and Bf 109s _flew_ at altitudes exceeding 30,000ft during the BoB.
They didn't fight there.
It was to position themselves for diving attacks where they would have an energy advantages or to deny the enemy the advantage of a diving attack.

Once the planes started to turn the fight was going to descend

http://www.spitfireperformance.com/spit109turn.gif

Turning charts for the Spitfire I and 109E.

The Spitfire I could only sustain a 3 g turn at 12,000ft doing about 225mph. If it flew faster or slower while pulling 3 Gs it would have to descend or bleed off speed. 
If it tried to pull a tighter turn it would bleed off speed. 
If it was pulling less than 3 Gs at 225mph it could climb. 

At higher altitudes things are going to be worse. Less lift from the wing and less power from the engine. This is the basic reason that fights that started at high altitudes (over 20,000ft) wound up much lower and even P-47s and P-51s had to spend a number of minutes climbing back up to escort altitudes after a fight. 

Just because you can fly in a straight line at high speed above 20,000ft doesn't mean the plane can actual fight there except in a very limited set of circumstances. 
This was one of the reasons for fitting the Merlin XX to the Hurricane II. To improve it's ability to fight at the higher altitudes.

Reactions: Like Like:
2 | Agree Agree:
1 | Like List reactions


----------



## Shortround6 (Jan 27, 2021)

Koopernic said:


> The thing about the Merlin XX is it leads to the 1600 hp Merlin 24 which was way ahead of any single stage Allison.


 Without the altitude at which the power is made the simple listing of power is useless. 

The Merlin 24 was rated at 1615hp at 2250 ft.

The engines in the P-39K and L were rated at 1580hp at 2500ft. at 60 in (15lbs or so).


----------



## glennasher (Jan 27, 2021)

The Soviets and the USAAF were fighting different wars, and it's obvious that the USAAF didn't think the P-39 was suitable for the war they were fighting in Northern Europe. I think we can all agree on that. The Bell simply didn't work for the USAAF and what they wanted (and needed) to accomplish. 
Since the Soviets weren't paying for the airplanes, and didn't have to take good care of them, they could fly them "balls to the wall" without any repercussions, and flew them with no regard for engine life or anything else, they simply didn't care. 
Either way you look at it, they appear to be "throwaway aircraft". There's no point in making a silk purse out of a sow's ear, at least the USAAF got it.

Reactions: Agree Agree:
2 | Like List reactions


----------



## GrauGeist (Jan 27, 2021)

P-39 Expert said:


> The Luftwaffe is not going to fly at low altitude just because some historian says the Eastern front was a low altitude war.




The airwar on the Eastern Front was focused on ground attack.
Since the Soviets moved their manufacturing beyond the Urals, there was no strategic bombing campaign like there was in the west.
Additionally, the Axis and Soviets were operating from foreward bases almost a stone's throw from one another - this is why combat altitudes rarely if ever exceeded 15,000 feet.

Think about it: if the enemy's positions were literally 15 minutes away, why would they need to climb any higher than nessecary?
Both sides were heavily involved in ground attack which involved tree-top altitudes with fighter cover roughly a few thousand feet above that - the defenders would be perhaps just a bit higher to both spot their adversary and have the height advantage.
So you have planes at maybe 150 feet, escorts at roughly 1-2 thousand and defenders at perhaps 3-4 thousand feet.

Bombers (both sides) would stay at heights just above mobile flak (only very strategic targets would have heavy flak replacements) and these altitudes would have been around 8-10,000 feet at best. Factor in their escorts being around or above and the defenders within a few thousand feet above.

The Eastern Front was a completely different type of war than existed in the West.

Reactions: Informative Informative:
1 | Like List reactions


----------



## GregP (Jan 27, 2021)

If you go read the history and reports, the Soviet Air Force ignored the high-flying Luftwaffe airplanes and sent in waves of low-altitude fighter and attack planes to decimate the German troops. So, the Luftwaffe had the choice of allowing their troops to be slaughtered or coming down to fight.

They chose to come down and fight rather than loose large numbers of troops, which they did anyway. In very cold weather, which was more often than not, the Soviet Air Force was flying while the Luftwaffe and other Allied Air Forces were grounded by simply not knowing how to operate in very cold weather. With the Soviets flying and the Luftwaffe not flying, the Soviets had a relatively easy time on very cold and bad weather days. The Germans could NOT allow them to just come in low and hit the troops, and that's why it was called a low-altitude war ... because that's where it was fought, down low.

It wasn't because the Luftwaffe planes couldn't fly high; they could. It was because they couldn't afford to ignore the Soviet low-altitude attacks on the German troops. You might remember that the Il-2/-10 was built VERY large numbers, and was very hard to shoot down from below due to very thick armor.

Reactions: Like Like:
1 | Like List reactions


----------



## P-39 Expert (Jan 28, 2021)

Ignoring enemy plains above you is the best way to become a statistic. Those planes had to be countered or your whole group could be lost.


----------



## tyrodtom (Jan 28, 2021)

P-39 Expert said:


> Ignoring enemy plains above you is the best way to become a statistic. Those planes had to be countered or your whole group could be lost.


Everybody already knows that.
What's your point ?


----------



## DerAdlerIstGelandet (Jan 28, 2021)

P-39 Expert said:


> Ignoring enemy plains above you is the best way to become a statistic. Those planes had to be countered or your whole group could be lost.



Oh, those vast green plains above, full of Buffallo grazing.

Reactions: Funny Funny:
2 | Like List reactions


----------



## SaparotRob (Jan 28, 2021)

I think the VVS pilots were more afraid of their squadron political officers back at the airfield than those FW-190’s circling above.

Reactions: Like Like:
1 | Agree Agree:
3 | Like List reactions


----------



## GregP (Jan 28, 2021)

They didn't completely ignore the high-flying Luftwaffe planes, they flew below them and attacked troops so the high fliers had to come down and fight or watch their troops get massacred. Once the Germans came down, they were in the Soviet best-performance altitude range and the fighters were more to the liking of the Soviet pilots.

Of course, all this was after the early Soviet defeats with obsolete aircraft that resulted in huge initial Luftwaffe scores. Once the Yak-3s and La-5s showed up, Russian air war was a different story than it was before the Soviet got better equipment. The Yak-9s and La-7s/9s were good airplanes, and Soviet tactics had morfed into a much better fighting force.

The air war on the Russian Front in late 1943 - early 1944 and beyond was a very different situation than it was in June 1941 when Operation Barbarossa began.

Reactions: Like Like:
2 | Like List reactions


----------



## pbehn (Jan 28, 2021)

The eastern front was huge, I believe it is a mistake to thing everything was focussed just on the line that made that front. The PE-2 was used on raids on Ploesti oil facilities, I presume they didn't travel at 50ft to and from the target. The German military had many targets to attack behind their lines. The Russians took over 1000 Spitfire Mk XVI ( packard engined Mk IXs) whick performed best at altitudes above those where the P-39 was best at.


----------



## Milosh (Jan 28, 2021)

*Most of the ~1200 Spitfire's delivered to the Soviet Union were used by the air defense forces (the PVO). *


----------



## SaparotRob (Jan 28, 2021)

Is the PVO part of or the same as VVS?


----------



## Dimlee (Jan 28, 2021)

SaparotRob said:


> Is the PVO part of or the same as VVS?


Separate branch with a different line of command.


----------



## Dimlee (Jan 28, 2021)

GregP said:


> If you go read the history and reports, the Soviet Air Force ignored the high-flying Luftwaffe airplanes and sent in waves of low-altitude fighter and attack planes to decimate the German troops. So, the Luftwaffe had the choice of allowing their troops to be slaughtered or coming down to fight.
> 
> They chose to come down and fight rather than loose large numbers of troops, which they did anyway. In very cold weather, which was more often than not, the Soviet Air Force was flying while the Luftwaffe and other Allied Air Forces were grounded by simply not knowing how to operate in very cold weather. With the Soviets flying and the Luftwaffe not flying, the Soviets had a relatively easy time on very cold and bad weather days. The Germans could NOT allow them to just come in low and hit the troops, and that's why it was called a low-altitude war ... because that's where it was fought, down low.
> 
> It wasn't because the Luftwaffe planes couldn't fly high; they could. It was because they couldn't afford to ignore the Soviet low-altitude attacks on the German troops. You might remember that the Il-2/-10 was built VERY large numbers, and was very hard to shoot down from below due to very thick armor.



A bit more complicated. 
Weather - VVS overall was poorly trained for all-weather operations. So there was no real advantage over LW. Low temperatures affected both sides but Soviets, indeed, were more inventive in keeping engines running with simple if not primitive equipment.
Kuban Stairs formation and tactics mentioned above were used against LW bombers and later in the war (when Geman bombers disappeared) against fighters in order to obtain local air dominance. It could help friendly bombers in the area, but it was not an escort itself.

Reactions: Like Like:
1 | Like List reactions


----------



## pbehn (Jan 28, 2021)

Dimlee said:


> A bit more complicated.
> Weather - VVS overall was poorly trained for all-weather operations. So there was no real advantage over LW. Low temperatures affected both sides but Soviets, indeed, were more inventive in keeping engines running with simple if not primitive equipment.
> Kuban Stairs formation and tactics mentioned above were used against LW bombers and later in the war (when Geman bombers disappeared) against fighters in order to obtain local air dominance. It could help friendly bombers in the area, but it was not an escort itself.


Did the VVS routinely attack targets behind the front line at altitudes above ground level?

Reactions: Funny Funny:
1 | Like List reactions


----------



## Dimlee (Jan 28, 2021)

pbehn said:


> Did the VVS routinely attack targets behind the front line at altitudes above ground level?



I think it became a routine later in the war when air superiority was gained. The so-called "free hunt" became a trademark of some units. There were, of course, some operations in the earlier period as well, as attacks against german transport flights to/from Stalingrad. Pe-3s attempted to hunt German bombers near their bases during the Battle of Moscow.

Reactions: Like Like:
1 | Informative Informative:
1 | Like List reactions


----------



## SaparotRob (Jan 28, 2021)

pbehn said:


> Did the VVS routinely attack targets behind the front line at altitudes above ground level?


I’m not sure what you wrote is what you meant but if you did,

Reactions: Agree Agree:
1 | Like List reactions


----------



## P-39 Expert (Jan 29, 2021)

GregP said:


> They didn't completely ignore the high-flying Luftwaffe planes, they flew below them and attacked troops so the high fliers had to come down and fight or watch their troops get massacred. Once the Germans came down, they were in the Soviet best-performance altitude range and the fighters were more to the liking of the Soviet pilots. *This was suicide. Inviting the Luftwaffe to bounce you until your unit was destroyed. *
> 
> Of course, all this was after the early Soviet defeats with obsolete aircraft that resulted in huge initial Luftwaffe scores. Once the Yak-3s and La-5s showed up, Russian air war was a different story than it was before the Soviet got better equipment. The Yak-9s and La-7s/9s were good airplanes, and Soviet tactics had morfed into a much better fighting force.
> 
> The air war on the Russian Front in late 1943 - early 1944 and beyond was a very different situation than it was in June 1941 when Operation Barbarossa began.


----------



## tyrodtom (Jan 29, 2021)

The use of high cover might have surprised the Luftwaffe the first time it was used, because they had little respect for the soviet's tactical thinking.

But after that do you think they wouldn't send it some aircraft at higher altitude to keep the high cover busy while other aircraft took care of the ground attack aircraft?

It's a simple concept, both sides were using high cover aircraft to cover other aircraft doing ground attack in late WW1, so the counter to that wasn't rocket science.

You seem to think people lose the ability to think when they're fighting a war.

Reactions: Agree Agree:
1 | Like List reactions


----------



## GregP (Jan 29, 2021)

Maybe you should read on Soviet tactics during the German invasion. Not "P-39 tactics," but general Soviet tactics. They attacked German troops with a combination of attack aircraft and fighters and bombers until the German pilots were forced to come down and fight at low altitude. 

It isn't my opinion, it's recorded history. If you don't recognize it as a good tactic, that's fine. It doesn't change the fact that it happened.

Reactions: Like Like:
1 | Agree Agree:
2 | Winner Winner:
1 | Like List reactions


----------



## glennasher (Jan 29, 2021)

It seems we've gone from P-39 groundhogs to P-39 clams now. I gotta go, I've never liked seafood. Wow, this place has zero rails.....................................................................


----------



## Peter Gunn (Jan 29, 2021)

Not me, I love seafood, in fact the wife and daughters and I are headed to Joe's Crabshack here on Gulf to Bay Blvd. tonight for dinner.


...


That's now what you meant? Sorry, I'll be leaving now.

Reactions: Funny Funny:
2 | Like List reactions


----------



## GrauGeist (Jan 29, 2021)

Wait, this isn't p39aircraft.net??

Reactions: Agree Agree:
1 | Funny Funny:
1 | Winner Winner:
2 | Like List reactions


----------



## buffnut453 (Jan 29, 2021)

GrauGeist said:


> Wait, this isn't p39aircraft.net??



It has been lately!

Reactions: Agree Agree:
2 | Like List reactions


----------



## Dimlee (Jan 29, 2021)

tyrodtom said:


> The use of high cover might have surprised the Luftwaffe the first time it was used, because they had little respect for the soviet's tactical thinking.
> 
> But after that do you think they wouldn't send it some aircraft at higher altitude to keep the high cover busy while other aircraft took care of the ground attack aircraft?
> 
> ...



This simple concept helped those who had the numerical advantage. Kuban Stairs were introduced when LW already had troubles with obtaining local superiority. VVS finally improved coordination and learned how to vector fighters in needed areas and fast. Typical "Stairs" formation consisted of 8 to 12 fighters. Apparently, their opponent used smaller formations most of the time.

Reactions: Like Like:
1 | Like List reactions


----------



## SaparotRob (Jan 30, 2021)

pbehn said:


> Did the VVS routinely attack targets behind the front line at altitudes above ground level?


I keep picturing squadrons of BiffF15’s P-39’s taxiing into battle. Post 18, Best Fixed Landing Gear Fighter.

Reactions: Funny Funny:
3 | Like List reactions


----------



## pbehn (Jan 30, 2021)

SaparotRob said:


> I keep picturing squadrons of BiffF15’s P-39’s taxiing into battle. Post 18, Best Fixed Landing Gear Fighter.


The altitude is for the attacking aircraft not the target.

Reactions: Agree Agree:
1 | Like List reactions


----------



## SaparotRob (Jan 30, 2021)

I know but my interpretation is far more amusing. 
I think we all got more use out of the P-39 than the USAAC.

Reactions: Funny Funny:
3 | Winner Winner:
3 | Like List reactions


----------



## Dimlee (Jan 31, 2021)

SaparotRob said:


> I keep picturing squadrons of BiffF15’s P-39’s taxiing into battle. Post 18, Best Fixed Landing Gear Fighter.



Against the German tanks. They were "tank busters" on the Eastern Front, weren't they.

Reactions: Agree Agree:
1 | Like List reactions


----------



## SaparotRob (Jan 31, 2021)

That would be a lot of firepower rolling down the plane at them!


----------



## SaparotRob (Jan 31, 2021)

See what I did there?

Reactions: Funny Funny:
1 | Like List reactions


----------



## buffnut453 (Jan 31, 2021)

SaparotRob said:


> See what I did there?



I was trying not to...but, like a train wreck, I couldn't look away!

Reactions: Agree Agree:
1 | Funny Funny:
3 | Like List reactions


----------



## rinkol (Feb 4, 2021)

b0ned0me said:


> Another possible reason is that the P39 was supposed to be the latest greatest wholly uncompromised land fighter and yet had barely any superiority over a warmed-up re-engined previous generation design and an almost contemporary (but older) design labouring under the necessary compromises of carrier operation.
> If the P39 had been a successful design it should have comfortably bested the P-40 and F4F at all heights on every performance metric, and had a decisive edge in combat. It didn’t, as far as I am aware.


I understand that it had stalling characteristics that were worse than most other aircraft.


----------



## P-39 Expert (Feb 4, 2021)

b0ned0me said:


> Another possible reason is that the P39 was supposed to be the latest greatest wholly uncompromised land fighter and yet had barely any superiority over a warmed-up re-engined previous generation design and an almost contemporary (but older) design labouring under the necessary compromises of carrier operation.
> If the P39 had been a successful design it should have comfortably bested the P-40 and F4F at all heights on every performance metric, and had a decisive edge in combat. It didn’t, as far as I am aware.


P-40E in green, A6M2 in red vs P-39K. F4F vs P-39K.


----------



## DerAdlerIstGelandet (Feb 4, 2021)

rinkol said:


> I understand that it had stalling characteristics that were worse than most other aircraft.



Get ready for an earful from the xpurt.

Reactions: Like Like:
1 | Funny Funny:
2 | Like List reactions


----------



## P-39 Expert (Feb 5, 2021)

rinkol said:


> I understand that it had stalling characteristics that were worse than most other aircraft.


Good stalling characteristics, just not much warning.

Reactions: Winner Winner:
1 | Like List reactions


----------



## DerAdlerIstGelandet (Feb 5, 2021)

Oh boy...


----------



## P-39 Expert (Feb 5, 2021)

DerAdlerIstGelandet said:


> Oh boy...


Not exactly an earful.

Reactions: Funny Funny:
2 | Like List reactions


----------



## pbehn (Feb 5, 2021)

If you take all the armour and guns out of the nose you can give the pilot a written warning a week before take off.

Reactions: Funny Funny:
1 | Like List reactions


----------



## P-39 Expert (Feb 5, 2021)

pbehn said:


> If you take all the armour and guns out of the nose you can give the pilot a written warning a week before take off.


I think there's a joke there, but I totally missed it.

Reactions: Funny Funny:
1 | Like List reactions


----------



## glennasher (Feb 5, 2021)

Clams, clams and more clams........................that no one really cares about.


----------



## tyrodtom (Feb 5, 2021)

P-39 Expert said:


> Good stalling characteristics, just not much warning.



You evidently don't know what stalling characteristics are.
How much warning a aircraft gives before it stalls is one of the more important stall characteristics.
When you're in the middle of a dogfight, you have to have you eyes outside the cockpit, not looking at the airspeed gauge, turn and bank, etc.
A aircraft that gives you no clue it's about to depart controlled flight isn't considered to have good stalling characteristics.

Reactions: Bacon Bacon:
1 | Like Like:
2 | Agree Agree:
2 | Like List reactions


----------



## DerAdlerIstGelandet (Feb 5, 2021)

P-39 Expert said:


> Not exactly an earful.



Except that little to no stall warning is an example of bad stall characteristics. Your unwillingness to comprehend that doesn’t make it not true.


----------



## P-39 Expert (Feb 5, 2021)

Obviously I don't. Pardon me for wasting your valuable time.


----------



## DerAdlerIstGelandet (Feb 5, 2021)

P-39 Expert said:


> Obviously I don't. Pardon me for wasting your valuable time.



Sorry, not trying to belittle you, but your post about stall characteristics says just that. I don’t think you are stupid, I don’t think you want to see it.

How an aircraft behaves before it enters a stall is part of its stall characteristics. To say that an aircraft has good or decent characteristics but hardly any warning is contradicting itself. Pilots learn what the aircraft feels like before a stall to keep it from entering a stall.

But we have been down this rabbit hole already way more times than we should have.


----------



## Shortround6 (Feb 5, 2021)

A number of post war or even jets in the 60s had artificial stall warning devices installed, like stick shakers, that would artificially shake the control column if the airspeed got too close to the stall speed. 

See. Stick shaker - Wikipedia

In many pre WW II or WW II aircraft the aerodynamic forces were such that the ailerons would snatch and shake the stick side to side near the stall, in others the elevator would oscillate givng a for and aft shake to the stick. Other aircraft just have part of the aircraft vibrate or make drumming noises(?). Some planes just sort of mushed. Obviously on aircraft without powered flight controls (which are almost always irreversible (moving the flight control surface outside the plane will not move the stick in the cockpit) it was a lot easier for the pilot to feel these movements of the control surfaces through the stick giving the pilot warning of the impending stall. 

The F4U might have had a worse stall than the P-39 (dropping one wing rather sharply) but may have given more warning.

Reactions: Like Like:
1 | Agree Agree:
2 | Like List reactions


----------



## pbehn (Feb 5, 2021)

tyrodtom said:


> You evidently don't know what stalling characteristics are.
> How much warning a aircraft gives before it stalls is one of the more important stall characteristics.
> When you're in the middle of a dogfight, you have to have you eyes outside the cockpit, not looking at the airspeed gauge, turn and bank, etc.
> A aircraft that gives you no clue it's about to depart controlled flight isn't considered to have good stalling characteristics.


As I understand it an aircraft can hold both properties, the Fw 190 was completely predictable and nice to fly in low "g" flying but would let go in a spectacular way when pushed in high "g" power on situations.


----------



## Glider (Feb 5, 2021)

P-39 Expert said:


> Good stalling characteristics, just not much warning.



The very definition of poor (make that very poor) stalling characteristics, in one line.


----------



## GregP (Feb 5, 2021)

The P-39 POH says it has "good stalling characteristics" and stalls at about 105 mph flaps up to 90 mph flaps down. It also says the airplane will "mush" considerably down around stall and, to completely unstall the center section, you need 130 - 140 mph! So, we have a plane that has "good stalling characteristics," but needs a 30 - 50 mph "cushion" of airspeed to be completely unstalled.

I think that describes "bad stall characteristics." Perhaps I am mistaken, but all the planes I have flown or flown in (includes warbirds) certainly don't need an airpseed "cushion" to untsall.


----------



## DerAdlerIstGelandet (Feb 5, 2021)

Shortround6 said:


> A number of post war or even jets in the 60s had artificial stall warning devices installed, like stick shakers, that would artificially shake the control column if the airspeed got too close to the stall speed.
> 
> See. Stick shaker - Wikipedia
> 
> ...



That is how the Cherokee I fly is (granted, it’s not a high performance warbird). When it gets close to a stall, the controls get mushy, and the airplane sort of begins to sort of wobble or porpoise (can’t really think of a word for it). Then the nose drops as the stall occurs. The plane recovers on its own once the nose drops. Of course if you are not coordinated when the stall occurs you run the risk of an inadvertent spin. I still remember my instructor yelling at me “Right rudder! Right rudder! Right rudder!”

Reactions: Like Like:
2 | Like List reactions


----------



## XBe02Drvr (Feb 5, 2021)

rinkol said:


> I understand that it had stalling characteristics that were worse than most other aircraft.





P-39 Expert said:


> Good stalling characteristics, just not much warning.





DerAdlerIstGelandet said:


> Except that little to no stall warning is an example of bad stall characteristics.





Glider said:


> The very definition of poor (make that very poor) stalling characteristics, in one line.


I think very few people who don't fly can truly wrap their head (and their gut) around "departure from controlled flight" as an experience. The gentle straight ahead pitchdown of a straight and level practice stall is so removed from a "departure" under G load as to seem almost unrelated to each other. A walking pony vs a bucking bronco. Even docile planes like a 152 or 172 can give you a pretty convincing rendition of a "departure" if you push them hard enough (only do this in Utility Category W&B conditions). A useful tool when dealing with an arrogant student who's gotten a bit too big for his britches. The T34 could really rattle your fillings and smack you against the canopy if you abused it under G load, while swapping sky for sea several times in quick succession. And it was just a glorified Bonanza. Someone should take our favorite Xpurt up and let him experience it for himself.

Reactions: Like Like:
2 | Agree Agree:
2 | Like List reactions


----------



## SaparotRob (Feb 5, 2021)

Read somewhere a long time ago that spins could be recovered from by letting go of the stick and giving the plane hard right rudder. This was developed by a pilot who bailed out his spinning plane only to see the empty plane recover by itself.


----------



## GrauGeist (Feb 5, 2021)

Our Cherokee Warrior got what felt like a tremor as the controls went soft.
But like Chris', as soon as it got nose-down attitude, she'd snap out of it.

Reactions: Like Like:
1 | Like List reactions


----------



## DerAdlerIstGelandet (Feb 5, 2021)

XBe02Drvr said:


> I think very few people who don't fly can truly wrap their head (and their gut) around "departure from controlled flight" as an experience. The gentle straight ahead pitchdown of a straight and level practice stall is so removed from a "departure" under G load as to seem almost unrelated to each other. A walking pony vs a bucking bronco. Even docile planes like a 152 or 172 can give you a pretty convincing rendition of a "departure" if you push them hard enough (only do this in Utility Category W&B conditions). A useful tool when dealing with an arrogant student who's gotten a bit too big for his britches. The T34 could really rattle your fillings and smack you against the canopy if you abused it under G load, while swapping sky for sea several times in quick succession. And it was just a glorified Bonanza. Someone should take our favorite Xpurt up and let him experience it for himself.



I hear you. I was not trying to compare a controlled induced training stall to a real departure from controlled flight. All stalls I have performed were always controlled. My point was only that our friend is contradicting himself.


----------



## XBe02Drvr (Feb 6, 2021)

SaparotRob said:


> Read somewhere a long time ago that spins could be recovered from by letting go of the stick and giving the plane hard right rudder.


Well actually, hard rudder against the rotation. Planes can spin to the right, as well, you know. Docile, lightweight General Aviation aircraft usually recover by relaxing the back pressure on the yoke, but heavier, higher performance planes often require a positive forward push to break the stall. Especially so if they're tending to flatten out in the spin.

Reactions: Informative Informative:
1 | Like List reactions


----------



## XBe02Drvr (Feb 6, 2021)

DerAdlerIstGelandet said:


> I hear you. I was not trying to compare a controlled induced training stall to a real departure from controlled flight. All stalls I have performed were always controlled. My point was only that our friend is contradicting himself.


I had no intention of rebutting or correcting you. I was just affirming your observation of the nonsensical nature of Xpurt's assertion.

Reactions: Like Like:
1 | Like List reactions


----------



## GrauGeist (Feb 6, 2021)

Bill Overstreet's experience with a P-39's shenanigans:


> Bill was in combat training in June 28th, 1943 when he had his first crash, at the controls of an Bell P-39 Airacobra, which went into a dreaded flat spin, a condition uniquely devastating for the model and which claimed many a pilot’s life. Bill and his squadron-mates were practicing aerobatic maneuvers when his plane strated tumbling and he couldn’t control it. Bill went to release the Airacobra’s doors but the air pressure prevented them from opening. He finally managed to get a knee against one door with his shoulder against the other, trying to overcome the pressure, and the moment he got out, he pulled the ripcord on his parachute. The moment the chute snapped open Bill found himself standing amidst the wreckage of his plane right by the propeller. He was so close to the ground when he escaped his doomed plane that none of his flight-mates even saw his chute deploy, Bill belives he was perhaps the first pilot to survive the crash of a tumbling P-39, and he made a point on tracking down the man who packed his chute to personally thank him for a job well done.








(Bill's P-39 crash site near Oroville, California)

Reactions: Like Like:
5 | Like List reactions


----------



## SaparotRob (Feb 6, 2021)

XBe02Drvr said:


> Well actually, hard rudder against the rotation. Planes can spin to the right, as well, you know. Docile, lightweight General Aviation aircraft usually recover by relaxing the back pressure on the yoke, but heavier, higher performance planes often require a positive forward push to break the stall. Especially so if they're tending to flatten out in the spin.


I thought that story was a bit simplistic. That procedure had fit in entirely too close to my “do nothing” approach to life.

Reactions: Agree Agree:
1 | Funny Funny:
1 | Like List reactions


----------



## tyrodtom (Feb 6, 2021)

SaparotRob said:


> Read somewhere a long time ago that spins could be recovered from by letting go of the stick and giving the plane hard right rudder. This was developed by a pilot who bailed out his spinning plane only to see the empty plane recover by itself.[/QUOTE
> 
> Pilots had figured out how to recover from spins several years before pilots started using parachutes.


----------



## Glider (Feb 6, 2021)

XBe02Drvr said:


> I think very few people who don't fly can truly wrap their head (and their gut) around "departure from controlled flight" as an experience. The gentle straight ahead pitchdown of a straight and level practice stall is so removed from a "departure" under G load as to seem almost unrelated to each other. A walking pony vs a bucking bronco. Even docile planes like a 152 or 172 can give you a pretty convincing rendition of a "departure" if you push them hard enough (only do this in Utility Category W&B conditions). A useful tool when dealing with an arrogant student who's gotten a bit too big for his britches. The T34 could really rattle your fillings and smack you against the canopy if you abused it under G load, while swapping sky for sea several times in quick succession. And it was just a glorified Bonanza. Someone should take our favorite Xpurt up and let him experience it for himself.



Going back far too many years I was an apprentice artificer in the FAA which is pretty much the lowest of the low, but I was an Air Experience Instructor in the gliding club. A group of Midshipmen who were learning to fly helicopters came to try gliding and I was tasked with taking one of them up. I was also only eighteen and everyone else was a fair bit older than me by which I mean twenty one plus so I did stand out. As luck would have it the one I was going to take up was very arrogant and really didn't like the idea of me taking him up, he had a PPL and had 'done it all before' and 'what could I teach him'. He moaned and bitched so much when we got to about 3,500 ft I gave him control and waited. It didn't take long and soon he was clearly getting into trouble and tried to give control back to me but I refused pointing out that 'he had done it before', so he could sort it out. In a couple more minutes he was really losing it, we were down to about 2,500ft when he stalled it and we entered a spin. He started yelling at me, so I took control sorted it out and we landed. 
He got out hugely embarrassed in a furious temper, all his friends were asking him what happened which he dared not answer. The CFI just asked me with a smile if everything was OK having a pretty good idea what had happened. 
Never saw him again, result all round. Practice over theory in one lesson, but to be fair spinning at about 1,500 to 2,000ft is a little scary the first time you do it.

Reactions: Bacon Bacon:
1 | Like Like:
4 | Winner Winner:
2 | Like List reactions


----------



## special ed (Feb 6, 2021)

In reading the book "Red Eagles" I learned the white stripe down the center of the MiG-23 instrument panel was to center the stick in line with the stripe and allow the aircraft to correct itself if in a spin or other departure from normal flight. I have since seen the stripe on the panels of museum pieces of MiG-17 and others. The MiG 23 had another feature which is not normally known, and that is when at high speed if throttle is pulled back quickly, an automatic device retards the throttle slowly to prevent pitchup. Good reading, "Red Eagles" as well as "Dark Eagles" and "Skunk Works".

Reactions: Informative Informative:
4 | Like List reactions


----------



## XBe02Drvr (Feb 6, 2021)

Glider said:


> Never saw him again, result all round. Practice over theory in one lesson, but to be fair spinning at about 1,500 to 2,000ft is a little


I was out for last flight of the day with one of the working students from the youth program collecting his compensation for the day's labors. Thermals were dying down, but there was a strong westerly flow aloft and the tug dragged us over under a lenticular WAY above, found us some nice lift, "rocked us off", and headed for home. There we were in a high speed elevator that seemed endless and were soon above all terrain within hundreds of miles, when the kid in front goes: "Hey, look at that cloud deck creeping in!". A cap cloud was rapidly forming above the mountains in front and below our altitude, and expanding outward towards us.
Holy crapola! A teachable moment. "We gotta get down, NOW! Full spoiler, nose down, max turbulence speed, we gotta find us some sink, quick! Read the sky. Visualize the wave. See that lennie overhead? We're in the lift now, gotta find the sink!" Still the smooth elevator wafting us upward despite all our efforts to shed altitude, and the cloud bank reaching out to envelop us. "Must be some mighty humid air coming in on this wind." Suddenly Godzilla has us in his fist and is shaking us silly. "There, that's the rotor. Sink should be on the other side." With a whump we exit into smooth air and the vario needle pegs down. Sink at last! But will we get below cloud base level before the deck catches us? Doesn't look good. We're diving away from it, but it's catching us.
"Okay, while we still have some visual reference, get stabilized, let the compass stop swinging, and trim for a descent at penetration speed....Alright, we're in it now, hands off the stick, feet lightly on the rudder pedals, and keep the compass steady with your feet. This won't keep you safe for long. Eventually the compass will get to swinging too much for you to keep up with and we'll wind up in a spiral which will quickly get out of hand. So what to do? Safest thing to do now is spin it. This baby stabilizes nicely in a spin, slow rotation, moderate descent rate, low airspeed, and minimum altitude loss in recovery. We're over the valley now, the wind is blowing us away from the mountains, so show me the smoothest spin entry of your life, and when she goes, hold full rudder into the spin and full back stick until we drop out the bottom....There you go, nice job! See, we've still got almost three thousand feet under the clouds and enough altitude to make the field, easy. Still, you better close the spoilers for now. How you feeling? You did great. A day to remember."
That student is now a 777 captain ten years from retirement.

Reactions: Like Like:
6 | Like List reactions


----------



## XBe02Drvr (Feb 6, 2021)

Glider said:


> we were down to about 2,500ft when he stalled it and we entered a spin. He started yelling at me, so I took control sorted it out and we landed.


That Schweizer TG2 I used to drool over as a 14 year old got wrecked the same way. The "student" an experienced powerplane pilot got it into a spin at 1100 feet AGL, and the instructor/owner told him to recover it.
"No, you! I don't know this plane!"
"Easy, recovers like any other. DO IT"
"No, you do it!"
Whump!
To those of us standing on the ground nearby there was no need for a Cockpit Voice Recorder.

Reactions: Like Like:
1 | Like List reactions


----------



## DerAdlerIstGelandet (Feb 6, 2021)

XBe02Drvr said:


> That Schweizer TG2 I used to drool over as a 14 year old got wrecked the same way. The "student" an experienced powerplane pilot got it into a spin at 1100 feet AGL, and the instructor/owner told him to recover it.
> "No, you! I don't know this plane!"
> "Easy, recovers like any other. DO IT"
> "No, you do it!"
> ...



Both of them...

idiots


----------



## XBe02Drvr (Feb 6, 2021)

DerAdlerIstGelandet said:


> Both of them...
> idiots


They both extricated themselves from the wreckage, climbed down the tree, and walked away, still pointing fingers and calling names. A hardheaded dutchman and a voluble Italian with the only injuries being to their egos.
A ship with a 52 foot wingspan, a 38 MPH best glide speed, and a max gross less than 900 pounds just doesn't spin into a tree all that hard.

Reactions: Funny Funny:
1 | Like List reactions


----------



## tyrodtom (Feb 6, 2021)

XBe02Drvr said:


> They both extricated themselves from the wreckage, climbed down the tree, and walked away, still pointing fingers and calling names. A hardheaded dutchman and a voluble Italian with the only injuries being to their egos.
> A ship with a 52 foot wingspan, a 38 MPH best glide speed, and a max gross less than 900 pounds just doesn't spin into a tree all that hard.



Still a lot of money down the drain though .


----------



## XBe02Drvr (Feb 6, 2021)

tyrodtom said:


> Still a lot of money down the drain though .


Not so much as you might think. John Daamen, the dutchman, bought it military surplus for (I think) $4-500 in 1959 from a warehouse where it had been sitting since 1945. It was a WWII training glider from the glider training base in Fulton NY which is now Oswego County Airport (NOO), a classic diamond shaped flat country USAAF fighter base replicated all over the country in WWII. There were only 67 TG2s built, and they had rugged fuselages and fragile wings so there are probably 67 TG2 fuselages out there and and only a few pairs of wings.


----------



## tyrodtom (Feb 6, 2021)

You mean he's got sweat equity in it , and he let some a-hole wreck it ?


----------



## XBe02Drvr (Feb 7, 2021)

tyrodtom said:


> You mean he's got sweat equity in it , and he let some a-hole wreck it ?


Actually the sweat equity was limited to assembling and disassembling, which is pretty simple with a glider, and a little bit of fabric patching and doping. The real sweat equity was in building the glider's launching winch and its transport trailer, neither of which was damaged in the mishap. When he gave up on trying to repair the ship, he sold the winch and trailer for $1,000, thus turning a tidy profit.
When the front seat guy lost control of it, John was "cooking" in the back seat, drowsy and half asleep, and he thought the other guy was competent to make the recovery, so delayed grabbing the controls. They argued briefly, then both grabbed at once and pulled in opposite directions, too late. A regular Keystone Kops episode. Fortunately that lightweight ship with its huge wingspan drifts downward in a lazy spin like a dry maple leaf in autumn. It's very much a "rudder" machine, as its glide speed is so slow and with its long wings, uncoordinated yawing can induce wingtip stalls. The guy up front was your typical "deadfoot" Cherokee nosedragger pilot. Probably never experienced adverse yaw in his life.

Reactions: Like Like:
2 | Like List reactions


----------



## XBe02Drvr (Feb 7, 2021)

I noticed as a glider instructor that powerplane nosedragger pilots habitually don't use enough rudder in a glider (myself included) until they realize what's missing and then use too much. They wind up chasing the yaw string (world's first HUD, BTW), testing the CFI's nausea threshold, until they begin to get it together. Taildragger pilots don't seem to have that problem. Funny thing about that!


----------



## warbird51 (Feb 8, 2021)

I used to be crew chief on the only flying Douglas B-23 Dragon in the late 80’s. We were coming back from the Livermore Airshow with about 1,000 gallons of fuel onboard. Denny, our chief pilot decided to do some power off stalls. I was kneeling between the pilots and watching the airspeed indicator. It got down to 45 when the stall occurred. The nose dropped and Denny relaxed the back pressure on the elevator. The a/c just flew right out of the stall. Very gental stall characteristics. Denny was a check airman on DC-3’s and he told me of a pilot who wanted to do a power on stall (which is prohibited). After much discussion, Denny fianally agreed only they went up to 10,000 feet. The DC-3 was empty with no seats in the back. Denny also said that if he calls “ my aircraft” he is to immediately release control back to him. So the pilot does a power on stall. When the a/c stalled, it rolled left to the inverted position and the nose dropped 30 degrees. Denny called “my aircraft” and recovered the a/c. He said the pilots eyes were as huge as saucers. Denny said to him “that’s why you don’t do a power on stall in a DC-3.

Reactions: Like Like:
4 | Winner Winner:
1 | Like List reactions


----------



## Glider (Feb 8, 2021)

XBe02Drvr said:


> I noticed as a glider instructor that powerplane nosedragger pilots habitually don't use enough rudder in a glider (myself included) until they realize what's missing and then use too much. They wind up chasing the yaw string (world's first HUD, BTW), testing the CFI's nausea threshold, until they begin to get it together. Taildragger pilots don't seem to have that problem. Funny thing about that!


That is essentially what happened to my midshipman. He got distracted trying to work out the rudder to use and didn't notice that we were leaving the field behind us. I pointed it out to him so he turned too quickly, lost all co-ordination in the controls, the glider started to shudder which panicked him, he froze and the rest as they say, is history.

Reactions: Like Like:
1 | Like List reactions


----------



## Shortround6 (Feb 9, 2021)

warbird51 said:


> I used to be crew chief on the only flying Douglas B-23 Dragon in the late 80’s. We were coming back from the Livermore Airshow with about 1,000 gallons of fuel onboard. Denny, our chief pilot decided to do some power off stalls. I was kneeling between the pilots and watching the airspeed indicator. It got down to 45 when the stall occurred. The nose dropped and Denny relaxed the back pressure on the elevator. The a/c just flew right out of the stall. Very gental stall characteristics. Denny was a check airman on DC-3’s and he told me of a pilot who wanted to do a power on stall (which is prohibited). After much discussion, Denny fianally agreed only they went up to 10,000 feet. The DC-3 was empty with no seats in the back. Denny also said that if he calls “ my aircraft” he is to immediately release control back to him. So the pilot does a power on stall. When the a/c stalled, it rolled left to the inverted position and the nose dropped 30 degrees. Denny called “my aircraft” and recovered the a/c. He said the pilots eyes were as huge as saucers. Denny said to him “that’s why you don’t do a power on stall in a DC-3.




Soooo....... Is the stall (unspecified type) characteristics of the DC-3 good or bad 

No answer required, you have made your point in an excellent way.

Reactions: Agree Agree:
2 | Like List reactions


----------



## P-39 Expert (Mar 8, 2021)

Shortround6 said:


> A number of post war or even jets in the 60s had artificial stall warning devices installed, like stick shakers, that would artificially shake the control column if the airspeed got too close to the stall speed.
> 
> See. Stick shaker - Wikipedia
> 
> ...


Agree. Would the stall/spin characteristics of a P-39 been better if the plane was lighter?


----------



## tyrodtom (Mar 8, 2021)

It would depend on where you removed the weight .

Reactions: Agree Agree:
1 | Like List reactions


----------



## DerAdlerIstGelandet (Mar 8, 2021)

Made it a whole month...lol

Reactions: Agree Agree:
1 | Funny Funny:
1 | Like List reactions


----------



## FLYBOYJ (Mar 8, 2021)

P-39 Expert said:


> Agree. Would the stall/spin characteristics of a P-39 been better if the plane was lighter?



"It would depend on where you removed the weight." 100%

As pointed out many times, spin/stall characteristics are more dependent on where the C/G is located as well as speed, bank angle and angle of attack


----------



## P-39 Expert (Mar 8, 2021)

tyrodtom said:


> It would depend on where you removed the weight .


Uh, yes, the CG would have to be maintained.

Point I was making was that 1942 P-39s could have been a lot lighter. Could have easily weighed 7150lbs instead of 7850lbs.

Reactions: Old Old:
2 | Like List reactions


----------



## XBe02Drvr (Mar 8, 2021)

P-39 Expert said:


> Uh, yes, the CG would have to be maintained.
> 
> Point I was making was that 1942 P-39s could have been a lot lighter. Could have easily weighed 7150lbs instead of 7850lbs.


Not *maintained; improved!! *It seems most P39s in combat trim, or even in training command, were flying around with CG at or near the aft limit, which may have itself been not conservative enough. A more forward CG increases the pitch-down tendency in a Departure From Controlled Flight (DFCF), reducing the probability of a flat spin. Given the concentration of mass in the core and the lack of polar inertia (a deliberate attempt to improve maneuverability), the impetus needed to get rotation started in a stall situation was pretty low. Add to that the easily blanked rudder and elevator configuration and you've got a potential booby trap for the inept or unwary pilot. Intuitive fliers like Yeager or Brown would naturally fly through a stall with precise coordination, thus avoiding yawing into the asymmetric stall condition that sets up a spin. Eagles of that caliber would of course enjoy the very light stick force gradients and the light "feel" of the plane, and would have the finesse to not overcontrol it as a more ham-handed pilot would.
So get that CG forward, if you can, and make it a better flying machine!

Reactions: Like Like:
1 | Agree Agree:
1 | Informative Informative:
1 | Like List reactions


----------



## GregP (Mar 8, 2021)

And, while you're at it, redesign it so it doesn't need a cushion of 40 knots of airpseed above the stall to not be mushy on the controls.

Reactions: Like Like:
2 | Agree Agree:
1 | Like List reactions


----------



## Peter Gunn (Mar 8, 2021)

XBe02Drvr said:


> *SNIP*
> 
> So get that CG forward, if you can, and make it a better flying machine!



I have a better idea, lengthen the nose, move the (Merlin) engine into it, square off the wings and tail, add a four bladed prop, stick the radiator in the belly behind the pilot and add 12 numbers to the designation.

Reactions: Bacon Bacon:
2 | Like Like:
1 | Winner Winner:
2 | Like List reactions


----------



## buffnut453 (Mar 8, 2021)

My deja vu is having deja vu....just sayin'.

Reactions: Like Like:
3 | Agree Agree:
1 | Like List reactions


----------



## fubar57 (Mar 8, 2021)



Reactions: Funny Funny:
2 | Winner Winner:
1 | Like List reactions


----------



## pbehn (Mar 8, 2021)

Peter Gunn said:


> I have a better idea, lengthen the nose, move the (Merlin) engine into it, square off the wings and tail, add a four bladed prop, stick the radiator in the belly behind the pilot and add 12 numbers to the designation.


My idea would be to take the engine out then go to the pub for a beer.

Reactions: Like Like:
1 | Agree Agree:
2 | Like List reactions


----------



## Thumpalumpacus (Mar 8, 2021)

Jeezly Crow, more groundhogs!

Reactions: Agree Agree:
1 | Like List reactions


----------



## DerAdlerIstGelandet (Mar 8, 2021)



Reactions: Like Like:
1 | Funny Funny:
4 | Like List reactions


----------



## glennasher (Mar 8, 2021)

pbehn said:


> My idea would be to take the engine out then go to the pub for a beer.




Take that Allison out and put it in a hydroplane and call it good. Then take the aluminum from the rest of the aircraft and send it to a foundry to make ANY other aircraft, wiping it out of our memories forever. Maybe then we'd get some peace from this monster that keeps cropping up and abusing this fine forum.


----------



## GregP (Mar 8, 2021)

Hi glennasher! Altogether a capital idea, old boy. Make mine a Spitfire Ale.






I say, we seem to out of Spitfire! Bollocks.

Reactions: Like Like:
4 | Like List reactions


----------



## XBe02Drvr (Mar 8, 2021)

Peter Gunn said:


> I have a better idea, lengthen the nose, move the (Merlin) engine into it, square off the wings and tail, add a four bladed prop, stick the radiator in the belly behind the pilot and add 12 numbers to the designation.


Hey, you forgot the laminar flow positive G airfoil!

Reactions: Agree Agree:
1 | Like List reactions


----------



## GregP (Mar 8, 2021)

Is that flow laminar into or out of the beer glass?

Reactions: Bacon Bacon:
1 | Like Like:
2 | Funny Funny:
1 | Like List reactions


----------



## XBe02Drvr (Mar 8, 2021)

GregP said:


> Is that flow laminar into or out of the beer glass?
> 
> View attachment 615473


Down the hatch! Minimum boundary layer turbulence. Maximum flow.


----------



## buffnut453 (Mar 9, 2021)

Since we're on a Spitfire Ale kick:

Reactions: Like Like:
1 | Funny Funny:
1 | Winner Winner:
1 | Like List reactions


----------



## GregP (Mar 9, 2021)

Thank God there's no Airacobra Ale! But Spitfire Ale, we got some of that.

And Messerschmitt Schnapps, too!







And maybe:






And last:





SOmehow, these seem to go together ... likely not strictly per the tech order, but seemingly related.

Reactions: Like Like:
1 | Agree Agree:
1 | Like List reactions


----------



## XBe02Drvr (Mar 9, 2021)

GregP said:


> Thank God there's no Airacobra Ale! But Spitfire Ale, we got some of that.
> 
> And Messerschmitt Schnapps, too!
> 
> ...


What about Wulfbrau?

Reactions: Like Like:
1 | Like List reactions


----------



## Peter Gunn (Mar 9, 2021)

XBe02Drvr said:


> Hey, you forgot the laminar flow positive G airfoil!


So typical of me, well, that's what happenzzzz afferr tooo mujch aleeelea... lallaall... aaaeelll... BEER.

Reactions: Like Like:
1 | Like List reactions


----------



## GregP (Mar 9, 2021)



Reactions: Like Like:
3 | Winner Winner:
1 | Like List reactions


----------



## P-39 Expert (Mar 9, 2021)

XBe02Drvr said:


> Not *maintained; improved!! *It seems most P39s in combat trim, or even in training command, were flying around with CG at or near the aft limit, which may have itself been not conservative enough. A more forward CG increases the pitch-down tendency in a Departure From Controlled Flight (DFCF), reducing the probability of a flat spin. Given the concentration of mass in the core and the lack of polar inertia (a deliberate attempt to improve maneuverability), the impetus needed to get rotation started in a stall situation was pretty low. Add to that the easily blanked rudder and elevator configuration and you've got a potential booby trap for the inept or unwary pilot. Intuitive fliers like Yeager or Brown would naturally fly through a stall with precise coordination, thus avoiding yawing into the asymmetric stall condition that sets up a spin. Eagles of that caliber would of course enjoy the very light stick force gradients and the light "feel" of the plane, and would have the finesse to not overcontrol it as a more ham-handed pilot would.
> So get that CG forward, if you can, and make it a better flying machine!


All the sources say that P-39 stalling characteristics were good, yet in the same sentence say that there was little or no stall warning. How can stall characteristics be good if there is no stall warning? Seems like if this is as critical as you say, then the stall characteristics should have been labeled "deadly" or "catastrophically bad" or something along those lines.


----------



## pbehn (Mar 9, 2021)

P-39 Expert said:


> All the sources say that P-39 stalling characteristics were good, yet in the same sentence say that there was little or no stall warning. How can stall characteristics be good if there is no stall warning? Seems like if this is as critical as you say, then the stall characteristics should have been labeled "deadly" or "catastrophically bad" or something along those lines.


As I understand it all aircraft stall, some give better warning than others, when close to stall some are still very controllable others very vague, when stall some are easy to recover and behave in a benign predictable way, others are not and become very dangerous very quickly.


----------



## DerAdlerIstGelandet (Mar 9, 2021)

pbehn said:


> As I understand it all aircraft stall, some give better warning than others, when close to stall some are still very controllable others very vague, when stall some are easy to recover and behave in a benign predictable way, others are not and become very dangerous very quickly.



And an aircraft’s characteristics regarding the warning leading up to the stall are part of whether it has good or poor stall characteristics. An aircraft that gives you no warning at all is not really ideal.

Reactions: Like Like:
2 | Agree Agree:
1 | Like List reactions


----------



## nuuumannn (Mar 9, 2021)

Whilst on a theme, we have this...

Reactions: Like Like:
1 | Like List reactions


----------



## GrauGeist (Mar 9, 2021)

There's a few breweries out there that have a Ju87 line. One is a Pilsner, one a Hefeweizen.

There is also this beer:

Reactions: Like Like:
1 | Like List reactions


----------



## Koopernic (Mar 9, 2021)

DerAdlerIstGelandet said:


> And an aircrafts characteristics regarding the warning leading up to the stall are part of whether it has good or poor stall characteristics. An aircraft that gives you no warning at all is not really ideal.




Test pilots often refer to characteristics such as 'stall annunciation' and 'departure characteristics'. There were differences in the stall when at low speed and not under high G and under high G where aeroelastic characteristics came in and wings might be untwisting. There was power on and power off stall. The Me 109 may not have been able to out turn a spitfire (maybe for a fraction of a turn its been argued) but it did have outstanding stall and spin recovery. Some aircraft flipped inverted and into a spin when they stalled others just mushed.

In the case of the Me 109 its good stall spin characteristics came from a long tail moment arm. Although the Me 109 is often described as having an NACA 4 digit wing this is not quite true. Messerschmitt used the NACA polynomial descriptor for the wing but also made use the modification system German aerodynamicist had developed (2R1) This was developed to give good pitching characteristics. Professor Messerschmitt's fame rests on techniques he developed to create such pitching characteristics.

An issue the P39 would need to have contended with was its tail moment arm and also the distribution of mass relative to the tail moment arm. Centre of Gravity are not all the same. The weight can be concentrated around the pitching axis of the wing but one could have a 'dumbbell' like distribution (extreme case Dornier Do 335) in which case the moment of inertial would be greater and something called inertia coupling could occur.

I think the P-39 suffered slightly from its mass distribution relative to its tail moment arm length. It does however look like the principle drag axis and the thrust axis probably align which means there would have been minimal pitch changes when power was adjusted.


----------



## XBe02Drvr (Mar 9, 2021)

P-39 Expert said:


> How can stall characteristics be good if there is no stall warning? Seems like if this is as critical as you say, then the stall characteristics should have been labeled "deadly" or "catastrophically bad" or something along those lines.





DerAdlerIstGelandet said:


> And an aircrafts characteristics regarding the warning leading up to the stall are part of whether it has good or poor stall characteristics. An aircraft that gives you no warning at all is not really ideal.





Koopernic said:


> Test pilots often refer to characteristics such as 'stall annunciation' and departure characteristics.


For "everyday Joes" like us, Adler's got it right, but in the rarefied world of aerodynamicists and test pilots (who write performance reports, BTW), it's more like Koopernic says, incipient stall warning and behavior in the stall are two separate topics, to be explored and reported separately.
*PS: *Any test pilot worth his salt is going to be a very precise flyer who's going to fly through every stall with perfect aileron-rudder coordination, thus not provoking the beast to display its nasties. It's what they do. If he happens to do a "sloppy" stall entry and experiences unpleasantness, and his boss is trying to sell airplanes, or trying to justify buying them, do you think he's likely to make an official big deal over it? Not if he wants to keep his job, and in the case of a civilian, his draft deferment. The infantry is always insatiable for bodies. He'll probably settle for planting a bug in the ears of the folks in the test and development shop.

Reactions: Like Like:
2 | Like List reactions


----------



## XBe02Drvr (Mar 10, 2021)

Koopernic said:


> Test pilots often refer to characteristics such as 'stall annunciation' and 'departure characteristics'. There were differences in the stall when at low speed and not under high G and under high G where aeroelastic characteristics came in


The more G there is on the aircraft at the stall break, the more critical symmetry becomes, and the less tolerance there is for any slipping or skidding. Many factors affect the pilot's ability to control this. Short tail planes like the P39 often have a deficit in rudder authority at high AoAs, and if they also have a short nose, the visual cues regarding rudder-aileron coordination can be frustratingly subtle. I remember several frustrating stall lessons with a student in his AA1 Yankee (the production version of Jim Bede's BD1). That little roller skate would snap into an incipient spin if coordination wasn't PERFECT, and yaw was very hard to see with its wide, short nose. It took my student a while to master it, but he got really good at spin avoidance. OTOH, the Cherokee 6, with its humungous schnozolla and equally long tail, was a dream to fly through any type of stall you wanted. A regular rocking chair. The Cessnas, from the 150 to the 210, all behaved pretty similarly in stalls, just with varying control pressures and muscle required. Solid, reliable, predictable. Likewise, Beechcraft singles, except the T34, which, with it's short, down sloping nose, required a lot of attention to get a zero yaw stall. It was kind of fun to deliberately stall her out of a high G turn, just to go for the ride. She would wind up pretty quick. Ah, the days of young and foolish!

Reactions: Like Like:
3 | Like List reactions


----------



## P-39 Expert (Mar 10, 2021)

P-39 stall characteristics were good but had little to no warning. Recovery was immediate with forward stick pressure in any configuration. The rest is just noise.


----------



## DerAdlerIstGelandet (Mar 10, 2021)

SMH...


----------



## DerAdlerIstGelandet (Mar 10, 2021)

Just noise...

I’m done with this. If I was not a moderator I would put someone on ignore.


----------



## Glider (Mar 10, 2021)

P-39 Expert said:


> P-39 stall characteristics were good but had little to no warning. Recovery was immediate with forward stick pressure in any configuration. The rest is just noise.


I know I am saying something that has already been said but the phrase' _P-39 stall characteristics were good but had little to no warning_' is a total contradiction in terms. 

As an example, a '_little or no warning stall_' on the approach to land will certainly result in a lot of noise. An aircraft hitting the ground, sirens from the ambulances and fire trucks do I agree make a lot of noise. It certainly doesn't make the description '_Stall characteristics were good_' even close to accurate. 

You seem to have missed the tendency of the P39 to go into a flat spin from your description as '_Stall characteristics were good_'

Reactions: Like Like:
4 | Like List reactions


----------



## FLYBOYJ (Mar 10, 2021)

P-39 Expert said:


> P-39 stall characteristics were good but had little to no warning. Recovery was immediate with *forward stick pressure in any configuration*. The rest is just noise.



Power on, gear and flaps up? I don't think so! It's quite evident you're just reading things (and mimicking) you fully don't understand!

Reactions: Bacon Bacon:
3 | Like List reactions


----------



## pbehn (Mar 10, 2021)

P-39 Expert said:


> P-39 stall characteristics were good but had little to no warning. Recovery was immediate with forward stick pressure in any configuration. The rest is just noise.


Do you read or only remember that which suits you? If your plane stalls in a high G turn without warning, will it recover with some forward stick pressure? There is a discussion of the Fw 190 Spitfire and P-51 aerodynamics posted on the forum. The Fw-190 was a great plane to fly in 1 G conditions, giving warning of a stall and being easily recoverable, in high G power on turns it would stall and tumble without warning in spectacular fashion, the top pilots used to practice doing it and used it as an escape gambit, if they had the altitude. In USA hands the P-39 was mainly used as an advanced trainer, the requirements of a trainer are different to a combat aircraft, you have to train people to fly without killing them in the process.

Reactions: Like Like:
2 | Like List reactions


----------



## glennasher (Mar 10, 2021)

DerAdlerIstGelandet said:


> Just noise...
> 
> I’m done with this. If I was not a moderator I would put someone on ignore.




I had to do just that, to keep my blood pressure within a safe range. It also keeps me from getting an aural hematoma from SMH like an old hound dog.

Reactions: Funny Funny:
1 | Winner Winner:
1 | Like List reactions


----------



## P-39 Expert (Mar 10, 2021)

FLYBOYJ said:


> Power on, gear and flaps up? I don't think so! It's quite evident you're just reading things (and mimicking) you fully don't understand!


Thank you for telling me yet again that I don't understand something. I believe I do understand exactly what I am talking about.

"Stalling characteristics are good, but there is little or no stall warning" is from virtually every description of P-39 stall characteristics. If the lack of stall warning is that serious, then stalling characteristics cannot be labeled as "good."

"In any condition, at any time after the stall occurred, recovery could be effected promptly by applying down elevator" is straight from "Measurements of the Flying Qualities of a Bell P-39D-1 Airplane (AAF No.41-28378)" from wwiiaircraftperformance.org.

Sorry this is not what you want to hear, but those are the facts.


----------



## pbehn (Mar 10, 2021)

P-39 Expert said:


> Thank you for telling me yet again that I don't understand something. I believe I do understand exactly what I am talking about.
> 
> "Stalling characteristics are good, *but there is little or no stall warning*" is from virtually every description of P-39 stall characteristics. If the lack of stall warning is that serious, then stalling characteristics cannot be labeled as "good."
> 
> ...


This means not good, and was one of many reasons the Supermarine Spiteful was shelved.


----------



## Glider (Mar 10, 2021)

P-39 Expert said:


> Thank you for telling me yet again that I don't understand something. I believe I do understand exactly what I am talking about.
> 
> "Stalling characteristics are good, but there is little or no stall warning" is from virtually every description of P-39 stall characteristics. If the lack of stall warning is that serious, then stalling characteristics cannot be labeled as "good."
> 
> ...



Sorry but clearly you are being very judicious in the examples you give. Even the quote you use is being interpreted selectively. Note the Line_* after the stall occurred*_. To use my example you are already dead because you had little or no warning of the stall. If you have altitude you may (note may, see next point) survive but without warning you are dead.

Point 2 . Please read the spinning test results also on the same site the following are the conclusions

Subject: Report of Spin Tests
Section: Flight
Serial No: ENG-47-1779-A

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.

Reactions: Bacon Bacon:
1 | Like Like:
2 | Winner Winner:
4 | Like List reactions


----------



## DerAdlerIstGelandet (Mar 10, 2021)

My recommendation? Everyone just walk away...


----------



## GrauGeist (Mar 10, 2021)

P-39 Expert said:


> Sorry this is not what you want to hear, but those are the facts


There are quite a few people here who have a considerable amount of flight experience (far beyond my time logged and in far more advanced types) who are trying to explain the difference between reading about stall characteristics and actually living through it.

We get that you're a proponent of the P-39 and that's fine, but no matter how you interpret the data will not change it's legacy.

Just a suggestion: go to your local airfield and see if a flight instructor would take you up up for a ride and show you some stalls.
Keep in mind that if they do, these will be done at a safe altitude AGL and not in combat situations, and they'll be done with a predictable recovery routine BUT will be an eye opening experience.


----------



## FLYBOYJ (Mar 10, 2021)

P-39 Expert said:


> Thank you for telling me yet again that I don't understand something. *I believe I do understand exactly what I am talking about.*
> 
> "Stalling characteristics are good, but there is little or no stall warning" is from virtually every description of P-39 stall characteristics. If the lack of stall warning is that serious, then stalling characteristics cannot be labeled as "good."
> 
> ...



If you did understand what you were talking about you would mention that stall recovery doesn't only consist of "pushing the stick forward." Again, you're just mimicking what you want to out of the flight manual.

So maybe now YOU will listen and understand that there are actually* SEVERAL* types of stalls and configurations - but you knew that, right?


----------



## XBe02Drvr (Mar 10, 2021)

FLYBOYJ said:


> If you did understand what you were talking about you would mention that stall recovery doesn't only consist of "pushing the stick forward." Again, you're just mimicking what you want to out of the flight manual.
> 
> So maybe now YOU will listen and understand that there are actually* SEVERAL* types of stalls and configurations - but you knew that, right?


If this old carcass was still airworthy, and there was a T34 or similar aircraft available, X-spurt and I would go up and experience a few things that have heretofore been only paper exercises. Just make sure he's got a helmet and chute on and he took his Dramamine.

Reactions: Bacon Bacon:
1 | Like Like:
2 | Winner Winner:
1 | Like List reactions


----------



## FLYBOYJ (Mar 10, 2021)

This is from a P-39Q Flight Manual - some observations;

The stall information shown is basically for a power-off stall gear up flaps down (Vs1). This is probably the most benign configuration and can be accomplished in straight and level flight. No mention of other stall configurations. I wonder why there is a caution note under spins!

Reactions: Like Like:
2 | Like List reactions


----------



## P-39 Expert (Mar 10, 2021)

We're talking about stalls, not spins. To spin a plane has to stall first. Spinning was prohibited in almost every AAF fighter flight manual. 

"In any condition" means clean, gear and flaps down and any combination thereof.

"At any time after the stall occurred" means just that.

"Recovery could be effected promptly by applying down elevator." Straight from an official test. Hard to argue with that, but know some of you will.


----------



## P-39 Expert (Mar 10, 2021)

Glider said:


> Sorry but clearly you are being very judicious in the examples you give. Even the quote you use is being interpreted selectively. Note the Line_* after the stall occurred*_. To use my example you are already dead because you had little or no warning of the stall. If you have altitude you may (note may, see next point) survive but without warning you are dead. *How can I be judicious by quoting the exact line from the report? Recovery was just that easy.*
> 
> Point 2 . Please read the spinning test results also on the same site the following are the conclusions
> 
> ...



Please see above.


----------



## XBe02Drvr (Mar 10, 2021)

Glider said:


> As an example, a '_little or no warning stall_' on the approach to land will certainly result in a lot of noise. An aircraft hitting the ground


...doesn't make all that much noise; just a sort of a "whump" (unless you're real close to ground zero). I've heard that sound five times, which is five times too many. One time, I even mistook it for the closing of the baggage door on a nearby Twin Otter.


----------



## FLYBOYJ (Mar 10, 2021)

P-39 Expert said:


> We're talking about stalls, not spins. To spin a plane has to stall first. Spinning was prohibited in almost every AAF fighter flight manual.


 Not in that P-39 manual and again it is cautioned.


P-39 Expert said:


> "In any condition" means clean, gear and flaps down and any combination thereof.


No, you're wrong - research stalling configurations and types, more than just putting the stick forward. 


P-39 Expert said:


> "At any time after the stall occurred" means just that.


Don't know what you're talking about on that one

Again it's quite evident you don't know different types of stalls and aircraft configurations aircraft can be stalled to.


----------



## FLYBOYJ (Mar 10, 2021)

P-39 Expert said:


> "Recovery could be effected promptly by applying down elevator." Straight from an official test. Hard to argue with that, but know some of you will.



You edited your post so I'll address that - yes, elevator straight down but that's not the only thing happening


----------



## tyrodtom (Mar 10, 2021)

Most spins occur when you stall while turning.
You tighten up the turn too much, the wing on the inside of the turn stalls first, it drops, and you've got a spin. 
I've flown, I've experienced this with a instructor, it's a eye opener.

And there's several members of this forum that has 100 of times more experience than I have, I would never consider disagreeing with them on stalls and spins.
And yet you, P-39 expert, evidently seem to think you know more from a little online research.

Reactions: Agree Agree:
4 | Like List reactions


----------



## DerAdlerIstGelandet (Mar 10, 2021)

I love this “Not having stall warning has no bearing on the stall characteristics of an aircraft” BS. You stall an aircraft at low altitude because there was no warning, you may not recover it before making a hole in the ground. Then this whole “we are talking about stalls not spins” BS is also tiring. If you stall without warning you are more likely to spin the aircraft.

Anybody else think this thread has run its course, serves no more purpose, and should go the way of the dodo bird?

Reactions: Agree Agree:
2 | Like List reactions


----------



## FLYBOYJ (Mar 10, 2021)

DerAdlerIstGelandet said:


> I love this “Not having stall warning has no bearing on the stall characteristics of an aircraft” BS. You stall an aircraft at low altitude because there was no warning, you may not recover it before making a hole in the ground. Then this whole “we are talking about stalls not spins” BS is also tiring. If you stall without warning you are more likely to spin the aircraft.
> 
> Anybody else think this thread has run its course, serves no more purpose, and should go the way of the dodo bird?



Yeah - it's like talking to a disconnected telephone


----------



## DerAdlerIstGelandet (Mar 10, 2021)

tyrodtom said:


> Most spins occur when you stall while turning.
> You tighten up the turn too much, the wing on the inside of the turn stalls first, it drops, and you've got a spin.
> I've flown, I've experienced this with a instructor, it's a eye opener.
> 
> ...



Yeap, I mentioned it earlier in this thread, but on my first cross country solo I was flying into my second destination. Tower told me to fly right traffic to avoid some obstacle. As I was turning base to final I misjudged my turn. I turned hard right to correct the turn. I was already at slow speed, and low altitude in the pattern. The high bank angle bled off even more speed, and the stall warning went off. I eased the bank angle, and prevented the stall. Then corrected my approach and performed one of the worst landings I have ever done. The entire situation scared the living shit out of me. At the altitude I was at, there was no chance of recovery had I stalled (and probably spun because I was uncoordinated at the time). It was a very humbling learning experience to say the least.

Now imagine this happening in low altitude combat in a high performance fighter aircraft with little to no stall warning...

Reactions: Like Like:
3 | Agree Agree:
2 | Like List reactions


----------



## DerAdlerIstGelandet (Mar 10, 2021)

I have the solution to all of these problems...

Take a P-39 and put Balkan Crosses on it, and rename it the Mustang and it will never stall, ever.

Reactions: Bacon Bacon:
1 | Funny Funny:
2 | Like List reactions


----------



## buffnut453 (Mar 10, 2021)

FLYBOYJ said:


> Yeah - it's like talking to a disconnected telephone



Sorry, were you saying something?

I couldn't resist!!

Reactions: Funny Funny:
1 | Like List reactions


----------



## XBe02Drvr (Mar 10, 2021)

P-39 Expert said:


> *We're talking about stalls, not spins. To spin a plane has to stall first. *Spinning was prohibited in almost every AAF fighter flight manual.


This is where your understanding falls short. Stalls and spins are parts of the same elephant. In fact a spin is basically a steady state partial stall; one wing firmly stalled while the other is still flying. That's what gives it the corkscrew motion, like a descending maple seed. Spins occur when one wing stalls before the other, usually as a result of a yawing motion, or a slipping or skidding condition as the critical AoA is approached. In this case the advancing wing experiences a slight increase in airspeed and reduction in AoA, while the retreating wing loses airspeed and its AoA goes critical, stalling the airflow, losing lift, and dramatically increasing drag. Retreating wing is dragged back and down, advancing wing gains airspeed and lift, rising up and over the top, while the windshield fills up with trees that start to go round and round and get bigger quickly. So there you are in a fully developed spin without ever fully stalling your airplane.
I just described a docile spin entry entered from 1 G level flight without a whole lot of power on the plane, caused by a "sloppy" approach to a stall. An instructor gets used to seeing this, as most students haven't developed the finesse yet to exert precise rudder-aileron coordination at high AoAs. That's why we devote a lot of attention to slow flight maneuvering before we start messing with stalls.
Now reenact this scenario in a 60° banked 2 G turn with the engine at full power to maintain altitude. As you approach critical AoA, the difference in lift between your faster traveling outboard wing and your inboard wing is starting to become significant, subtly changing the balance point of rudder-aileron coordination. With 2 Gs on, the consequences of any inadvertent asymmetry will radically increase the rolling motion when one wing stalls before the other, likely resulting in a head banger.
Now put yourself in a P39, an FW190, a P40, or fighter of your choice, pulling 4 Gs with tracers zinging under your tailfeathers from a bad guy "saddled up" in your six. Wouldn't it be nice to have a buffet or a burble, or even a stall horn to let you know that if you pull just a little harder, you're going to snap roll into his line of fire?

Reactions: Bacon Bacon:
1 | Like Like:
1 | Winner Winner:
3 | Like List reactions


----------



## P-39 Expert (Mar 10, 2021)

FLYBOYJ said:


> Not in that P-39 manual and again it is cautioned.
> 
> No, you're wrong - research stalling configurations and types, more than just putting the stick forward.
> 
> ...


I know that "any configuration" means just that. Why are you trying to disagree with an official performance test conducted by the NACA for the AAF? It's right there in black and white. That's all new material, only posted to the wwiiaircraft site in 2012. You persist in quoting 75 year old heresay when you have the actual report right there. 

And please keep telling me that I don't know what I am talking about when I'm quoting verbatim an official report. And please tell the posters on here to keep insulting me with comments like "SMH", like I don't know what that means. Can we have a grownup discussion here? That means people expressing differing views in a civilized manner.


----------



## tyrodtom (Mar 10, 2021)

P-39 Expert said:


> I know that "any configuration" means just that. Why are you trying to disagree with an official performance test conducted by the NACA for the AAF? It's right there in black and white. That's all new material, only posted to the wwiiaircraft site in 2012. You persist in quoting 75 year old heresay when you have the actual report right there.
> 
> And please keep telling me that I don't know what I am talking about when I'm quoting verbatim an official report. And please tell the posters on here to keep insulting me with comments like "SMH", like I don't know what that means. Can we have a grownup discussion here? That means people expressing differing views in a civilized manner.



You're quoting a report meant to be read by pilots, it presupposes more than a little knowledge of aviation.

Reactions: Like Like:
1 | Agree Agree:
2 | Like List reactions


----------



## pbehn (Mar 10, 2021)

United States World War II Aircraft Loss Statistics during Flight Training

The P-39 had 1,934 accidents in USA training, 369 were fatal involving 395 deaths and 865 planes destroyed an accident rate of 245 per 100,000, this by far the worst of any S/E type used apart from the A-36 which was a dive bomber.


----------



## P-39 Expert (Mar 10, 2021)

XBe02Drvr said:


> This is where your understanding falls short. Stalls and spins are parts of the same elephant. In fact a spin is basically a steady state partial stall; one wing firmly stalled while the other is still flying. That's what gives it the corkscrew motion, like a descending maple seed. Spins occur when one wing stalls before the other, usually as a result of a yawing motion, or a slipping or skidding condition as the critical AoA is approached. In this case the advancing wing experiences a slight increase in airspeed and reduction in AoA, while the retreating wing loses airspeed and its AoA goes critical, stalling the airflow, losing lift, and dramatically increasing drag. Retreating wing is dragged back and down, advancing wing gains airspeed and lift, rising up and over the top, while the windshield fills up with trees that start to go round and round and get bigger quickly. So there you are in a fully developed spin without ever fully stalling your airplane.
> I just described a docile spin entry entered from 1 G level flight without a whole lot of power on the plane, caused by a "sloppy" approach to a stall. An instructor gets used to seeing this, as most students haven't developed the finesse yet to exert precise rudder-aileron coordination at high AoAs. That's why we devote a lot of attention to slow flight maneuvering before we start messing with stalls.
> Now reenact this scenario in a 60° banked 2 G turn with the engine at full power to maintain altitude. As you approach critical AoA, the difference in lift between your faster traveling outboard wing and your inboard wing is starting to become significant, subtly changing the balance point of rudder-aileron coordination. With 2 Gs on, the consequences of any inadvertent asymmetry will radically increase the rolling motion when one wing stalls before the other, likely resulting in a head banger.
> Now put yourself in a P39, an FW190, a P40, or fighter of your choice, pulling 4 Gs with tracers zinging under your tailfeathers from a bad guy "saddled up" in your six. Wouldn't it be nice to have a buffet or a burble, or even a stall horn to let you know that if you pull just a little harder, you're going to snap roll into his line of fire?



Yet again, you're going an awfully long way here and you are not proving anything, except to tell me that I don't understand something. Please keep insulting me, it's always appreciated. Your example is applicable to any WWII fighter plane, including those with abysmal stalling characteristics.


----------



## DerAdlerIstGelandet (Mar 10, 2021)

P-39 Expert said:


> I know that "any configuration" means just that. Why are you trying to disagree with an official performance test conducted by the NACA for the AAF? It's right there in black and white. That's all new material, only posted to the wwiiaircraft site in 2012. You persist in quoting 75 year old heresay when you have the actual report right there.
> 
> And please keep telling me that I don't know what I am talking about when I'm quoting verbatim an official report. And please tell the posters on here to keep insulting me with comments like "SMH", like I don't know what that means. Can we have a grownup discussion here? That means people expressing differing views in a civilized manner.



I never doubted that you know what SMH means (its the one thing I don’t doubt). I am SMH because of your posts. If someone shaking their head insults you, thats your problem and maybe you should figure out why.


----------



## DerAdlerIstGelandet (Mar 10, 2021)

P-39 Expert said:


> Yet again, you're going an awfully long way here and you are not proving anything, except to tell me that I don't understand something. Please keep insulting me, it's always appreciated. Your example is applicable to any WWII fighter plane, *including those with abysmal stalling characteristics.*



Like the P-39?


----------



## FLYBOYJ (Mar 10, 2021)

P-39 Expert said:


> I know that "any configuration" means just that. Why are you trying to disagree with an official performance test conducted by the NACA for the AAF? It's right there in black and white. That's all new material, only posted to the wwiiaircraft site in 2012. You persist in quoting 75 year old heresay when you have the actual report right there.


Because it's not as simple as what you're trying to make it. You don't even understand that there are different types of stalls and configurations and that manual is not addressing those configurations and you continue to NOT under stand the bigger picture either by ignorance or stubbornness - typical armchair response.


P-39 Expert said:


> And please keep telling me that I don't know what I am talking about when I'm quoting verbatim an official report. And please tell the posters on here to keep insulting me with comments like "SMH", like I don't know what that means. Can we have a grownup discussion here? That means people expressing differing views in a civilized manner.


We are/ were having a grown up discussion but its YOU who continually tries to second guess some of us who have flown and worked on aircraft, some of these folks are former military pilots and ATPs who have hundreds if not thousands of hours flying. Your "hands on" aviation experience??????

No - you're creating your own firestorm by some of your own assumptions and refusing to listen to real world experience. If this is too overwhelming for you I can suggest one thing....

Reactions: Agree Agree:
1 | Like List reactions


----------



## P-39 Expert (Mar 10, 2021)

pbehn said:


> United States World War II Aircraft Loss Statistics during Flight Training
> 
> The P-39 had 1,934 accidents in USA training, 369 were fatal involving 395 deaths and 865 planes destroyed an accident rate of 245 per 100,000, this by far the worst of any S/E type used apart from the A-36 which was a dive bomber.


The primary role of the P-39 in the AAF from 1943 forward was advanced combat training. One would expect more accidents from pilot trainees than graduate combat pilots who had moved on to P-38s, P-47s and P-51s. Also consider the average length of each mission by type. Those P-39s held 120 gallons internal, some only 88 gallons. If they average 108 gallons each and burn 100gallons/hour then they are making 92,600 takeoffs/landings per 100000hours. A P-38 or P-40 held 150gal per engine, meaning 1.5hrs per flight or 66,670 takeoffs/landings per 100000hrs. A P-51 held 265gal or 2.65hrs per flight or 37,750 takeoffs/landings. P-47s held 305gal and burned an average of, say 150gph or 2 hours per flight. They averaged 50000 takeoffs/landings per 100000hrs. A P-39 would then make 1.4 times as many takeoffs/landings than a P-38 or P-40, 2.5 times as many as a P-51 and 1.9 times as many as a P-47. A P-38 would have 195 accidents per takeoff/landing, a P-40 would have 263 accidents per TO/L, a P-51 would have 262 per TO/L and the P-47 would have 241 accidents per TO/L. All pretty close to the P-39 with 245. All about the same, really. And the P-39 was being flown by trainees while the other models were being flown by graduate pilots. Just another way to look at it.


----------



## nuuumannn (Mar 10, 2021)

This is turning into the Lancaster as an Atom Bomber thread. Pretty soon they'll be hanging a Fat Man under a P-39, claiming it has no detrimental impact on its aerodynamics because a turret's been removed and flying it from Okinawa to successfully bomb Nagasaki... Anything I missed?

Reactions: Like Like:
1 | Funny Funny:
3 | Winner Winner:
1 | Like List reactions


----------



## pbehn (Mar 10, 2021)

P-39 Expert said:


> The primary role of the P-39 in the AAF from 1943 forward was advanced combat training. One would expect more accidents from pilot trainees than graduate combat pilots who had moved on to P-38s, P-47s and P-51s. Also consider the average length of each mission by type. Those P-39s held 120 gallons internal, some only 88 gallons. If they average 108 gallons each and burn 100gallons/hour then they are making 92,600 takeoffs/landings per 100000hours. A P-38 or P-40 held 150gal per engine, meaning 1.5hrs per flight or 66,670 takeoffs/landings per 100000hrs. A P-51 held 265gal or 2.65hrs per flight or 37,750 takeoffs/landings. P-47s held 305gal and burned an average of, say 150gph or 2 hours per flight. They averaged 50000 takeoffs/landings per 100000hrs. A P-39 would then make 1.4 times as many takeoffs/landings than a P-38 or P-40, 2.5 times as many as a P-51 and 1.9 times as many as a P-47. A P-38 would have 195 accidents per takeoff/landing, a P-40 would have 263 accidents per TO/L, a P-51 would have 262 per TO/L and the P-47 would have 241 accidents per TO/L. All pretty close to the P-39 with 245. All about the same, really. And the P-39 was being flown by trainees while the other models were being flown by graduate pilots. Just another way to look at it.


If taking off and landing is an issue with your tricycle undercart advanced trainer you need to take a look at your basic training aircraft and methods. What on earth makes you think all training missions used full tanks and ran them to empty?


----------



## fubar57 (Mar 10, 2021)

Interesting quote from Zenos, "The 39 was widely used as a trainer in the US and had a reputation for weeding out poor pilots -- permanently."

Reactions: Like Like:
1 | Funny Funny:
1 | Winner Winner:
3 | Like List reactions


----------



## P-39 Expert (Mar 10, 2021)

FLYBOYJ said:


> Because it's not as simple as what you're trying to make it. You don't even understand that there are different types of stalls and configurations and that manual is not addressing those configurations and you continue to NOT under stand the bigger picture either by ignorance or stubbornness - typical armchair response. * I believe it's exactly as simple as I'm making it: the report (not a manual) investigated stalls in the landing configuration with gear and flaps down, landing approach with gear and flaps down, climbing with gear and flaps up, cruising with gear and flaps up, gliding with gear and flaps up and takeoff emergency. In any condition at any time after the stall occurred recovery could be effected promptly by applying down elevator. There was no warning but recovery was prompt and easy.*
> 
> 
> FLYBOYJ said:
> ...



See above.


----------



## Shortround6 (Mar 10, 2021)

nuuumannn said:


> This is turning into the Lancaster as an Atom Bomber thread. Pretty soon they'll be hanging a Fat Man under a P-39, claiming it has no detrimental impact on its aerodynamics because a turret's been removed and flying it from Okinawa to successfully bomb Nagasaki... Anything I missed?



Yep, the return flight with a rescued nurse in skimpy clothing sitting on the pilots lap

Reactions: Like Like:
1 | Like List reactions


----------



## fubar57 (Mar 10, 2021)

[QUOTE="nuuumannn, post: 1625029, member: 44325"... Anything I missed?[/QUOTE]

Reactions: Agree Agree:
1 | Funny Funny:
1 | Winner Winner:
1 | Like List reactions


----------



## buffnut453 (Mar 10, 2021)

Please don't lock this thread....if we can't get in, who will look after the groundhogs? I'm worried about those little critters.

Reactions: Like Like:
1 | Funny Funny:
6 | Like List reactions


----------



## gumbyk (Mar 10, 2021)

P-39 Expert said:


> See above.


That is hardly an exhaustive list of configurations. Straight and level or turning? How many G's? Accelerated or not?

Most aircraft will behave differently in an accelerated stall than with a slow approach.

Reactions: Winner Winner:
2 | Like List reactions


----------



## glennasher (Mar 10, 2021)

buffnut453 said:


> Please don't lock this thread....if we can't get in, who will look after the groundhogs? I'm worried about those little critters.





Looking after groundhogs is easy, I use a .17 or .22 Hornet, or a .221 Fireball, or a .204 Ruger, but I've also used 6mm Remington, .308 Winchester, and the ever popular .223 and .22/250s. I've even used the .22 and .17 rimfires, which add stalking skills and patience to the mix. Groundhogs are fun.


----------



## FLYBOYJ (Mar 10, 2021)

P-39 Expert said:


> *I believe it's exactly as simple as I'm making it: the report (not a manual) investigated stalls in the landing configuration with gear and flaps down, landing approach with gear and flaps down, climbing with gear and flaps up, cruising with gear and flaps up, gliding with gear and flaps up and takeoff emergency. In any condition at any time after the stall occurred recovery could be effected promptly by applying down elevator. There was no warning but recovery was prompt and easy.*


My whole reference was what I posted from *the manual (Post 397)* but considering you want to ignore that and use other references that are now more detailed, I'll play -

now you're refencing configurations but lacking the stall type (because you don't now how to identify them by their proper nomenclature) and I can tell you it's a little more complicated by "applying down elevator." What are you feet doing? Are you straight and level? Pitch attitude? Speed? - I see no mention of bank angle.

*No stall warning is a horrible trait to have on any aircraft!*

*


P-39 Expert said:



I have no hands on experience. How many P-39s have you flown?

Click to expand...

*
*None* - but since I've flown and maintained a number of general aviation aircraft (Commercial Pilot, CFII A&P/IA) gliders, helicopters and several high performance jets and warbirds *I think that puts me about 10000 times more experienced about flying aircraft than you can ever dream of being!*

*AND THERE HAVE BEEN PEOPLE ON HERE WITH WAY MORE AVIATION EXPERIENCE THAN ME ATTEMPING TO "SHOW YOU THE WAY" TO NO AVAIL!*

*


P-39 Expert said:



Are you asking me to leave or banning me from the forum? For pointing out information that people on here obviously did not know?

Click to expand...

*
*No I'm not going to ban you and if you want to stay around, it's up to you. You're the one on here butt-hurt and complaining about some members who have on more than one occasion shown your armchair aviation education **attempting** to point out WRONG or incomplete information. *


----------



## FLYBOYJ (Mar 10, 2021)

gumbyk said:


> That is hardly an exhaustive list of configurations. Straight and level or turning? How many G's? Accelerated or not?
> 
> Most aircraft will behave differently in an accelerated stall than with a slow approach.



Exactly! And if our friend would care to listen, maybe we can teach him something (like the way we taught him weight and balance )


----------



## P-39 Expert (Mar 10, 2021)

FLYBOYJ said:


> Exactly! And if our friend would care to listen, maybe we can teach him something (like the way we taught him weight and balance )


You made up that little chart, really good info. Otherwise not much new. You sure are quick to assume somebody doesn't know something.


----------



## FLYBOYJ (Mar 10, 2021)

P-39 Expert said:


> You made up that little chart, really good info. Otherwise not much new. You sure are quick to assume somebody doesn't know something.


Because by some of your statements to me and others on here it's evident when you don't know something and trying to fake it!

I've had no issues saying when you're right but will continue to point out when you point out wrong or incomplete information.


----------



## gumbyk (Mar 10, 2021)

FLYBOYJ said:


> Because by some of your statements to me and others on here it's evident when you don't know something!


I don't think anyone has said you don't know something. However, you don't have the experience in order to be able to put that knowledge into some sort of context.
Context is everything.

Reactions: Bacon Bacon:
1 | Winner Winner:
1 | Like List reactions


----------



## FLYBOYJ (Mar 10, 2021)

FLYBOYJ said:


> Because by some of your statements to me and others on here it's evident when you don't know something!





P-39 Expert said:


> You made up that little chart, really good info. Otherwise not much new. You sure are quick to assume somebody doesn't know something.


And by the way - Greg made that chart


----------



## pbehn (Mar 10, 2021)

FLYBOYJ said:


> *No stall warning is a horrible trait to have on any aircraft!*


I have no idea why this is difficult to understand, our whole lives is built on warnings. Imagine if things didn't bend just broke, dogs didn't bark they just bit you. Imagine arguing that cars with no lights, no horn, a silent engine on roads with no signs wouldn't be a problem.

Reactions: Bacon Bacon:
1 | Like List reactions


----------



## GregP (Mar 10, 2021)

Hi P-39 Expert,

We recently had a thread with over 100 pages of posts, almost all of which were by you or exclusively directed at you, so Flyboyj getting a bit upset didn't exactly happen in a "quick" fashion. He was far slower to get "upset" than many other members. 

Just to make it plain, the entire forum is very tired of hearing about how great the P-39 was. Its war record didn't reflect that in US service, it didn't have the range or altitude capability to do the job the US needed in most theaters, and it had a few rather bad characteristics. The fataility rate was high. No amount of analysis will change that or excuse it.

Reactions: Bacon Bacon:
2 | Like Like:
2 | Agree Agree:
4 | Winner Winner:
1 | Like List reactions


----------



## XBe02Drvr (Mar 10, 2021)

glennasher said:


> Looking after groundhogs is easy, I use a .17 or .22 Hornet, or a .221 Fireball, or a .204 Ruger, but I've also used 6mm Remington, .308 Winchester, and the ever popular .223 and .22/250s. I've even used the .22 and .17 rimfires, which add stalking skills and patience to the mix. Groundhogs are fun.


Want some real fun? Try a .45 call roundball flintlock Kentucky with 1 in 66 twist! Lots of stalking and patience goes with the territory, but you'll also have to guess which way the critter will jump when the pan flashes, as he'll already be in motion when your ball gets there. Not for the instant gratification crowd, but a real kick when you do score.

Reactions: Like Like:
1 | Like List reactions


----------



## nuuumannn (Mar 10, 2021)

buffnut453 said:


> I'm worried about those little critters.



You needn't be. If past evidence is anything to go by, those sneaky wee varmints get around of their own volition.


----------



## XBe02Drvr (Mar 10, 2021)

P-39 Expert said:


> Yet again, you're going an awfully long way here and you are not proving anything, except to tell me that I don't understand something. Please keep insulting me, it's always appreciated. Your example is applicable to any WWII fighter plane, including those with abysmal stalling characteristics.


Nothing needs proving. These are known facts to anyone who has the background, the training, and the need or desire to know and understand them. They exist whether you accept and acknowledge them or not. They are more easily absorbed by someone who has hands on experience in flight, but they aren't rocket science, and can be comprehended by anyone willing to make the effort.
As for "any WWII fighter plane", no other fighter of the time had as low a polar inertia as the P39. No other plane had as high a percentage concentration of its mass amidships as the P39, making it the least resistant to rotation in a stall situation of all of them. No other fighter (except possibly the Merlin Mustang in some cases) did as much flirting with its aft CG limit. Both of these features (low polar inertia and aft CG) are stability detractors, increasing both the probability and the severity of a departure in a stall situation. Add to that, the "light" touch on the controls and the jerky overcontrolling of a panicked inept pilot, and you've got a potential deathtrap. Not the type of "honest flying airplane" to instill confidence in nugget aviators and their instructors.
And when calculating accident rates in advanced fighter training, bear in mind that few syllabus flights are longer than two hours (except cross country navigation flights), regardless of aircraft tankage. Most average from 1 to 1 1/2 hours. Longer than that tends to become counterproductive in terms of learning curve.

Reactions: Like Like:
2 | Agree Agree:
3 | Like List reactions


----------



## FLYBOYJ (Mar 10, 2021)

_"In any condition at any time after the stall occurred recovery could be effected promptly by applying down elevator. There was no warning but recovery was* prompt and easy*."_

Departure stall, full power, gear and flaps down, 25 degree pitch then 45 degree bank angle to the left. 

Who thinks recovery will be "prompt and easy" if no stall warning is exhibited?

OK - I'm done...

Reactions: Agree Agree:
1 | Like List reactions


----------



## Glider (Mar 10, 2021)

XBe02Drvr said:


> ...doesn't make all that much noise; just a sort of a "whump" (unless you're real close to ground zero). I've heard that sound five times, which is five times too many. One time, I even mistook it for the closing of the baggage door on a nearby Twin Otter.


I stand corrected, but we can agree on the sirens


----------



## Glider (Mar 10, 2021)

P-39 Expert said:


> See above.


Which part of:-

If you stall with little or no warning at low altitude, then there is an excellent chance you will hit the ground before you can recover.

Do you not understand?

Reactions: Like Like:
1 | Like List reactions


----------



## Graeme (Mar 10, 2021)

Not even loved by Bell?







(Aeroplane - January 2021)

Reactions: Bacon Bacon:
1 | Like Like:
1 | Like List reactions


----------



## GrauGeist (Mar 11, 2021)

I know in the other thread that my comment about my Uncle Jimmy's sentiments about the P-39 were laughed off, but let's recap:
A USAAC trained pilot, who would have gladly and willingly taken on the Empire of Japan in his P-36 said that "your life is not worth a plugged nickel in a P-39" has to have some gravity.
This was coming from a veteran Army pilot who was at Pearl Harbor on 7 December and later flew a P-38 in the PTO for the duration.

I'll take his word as gospel because he actually FLEW a P-39 - so unless you've actually trained/flown a P-39, sit down and shut the eff up.

Reactions: Bacon Bacon:
4 | Like Like:
1 | Like List reactions


----------



## buffnut453 (Mar 11, 2021)

glennasher said:


> Looking after groundhogs is easy, I use a .17 or .22 Hornet, or a .221 Fireball, or a .204 Ruger, but I've also used 6mm Remington, .308 Winchester, and the ever popular .223 and .22/250s. I've even used the .22 and .17 rimfires, which add stalking skills and patience to the mix. Groundhogs are fun.



But not if the groundhogs have nose armor. Plus anything less than a 50 cal is useless from an armament perspective....at least according to one person on this thread.

Reactions: Funny Funny:
2 | Like List reactions


----------



## XBe02Drvr (Mar 11, 2021)

Graeme said:


> Not even loved by Bell?
> 
> View attachment 615688
> 
> ...


Interesting. Looks like nobody even bothered to paint over the flight test photogrammetry "targets" on this one. "Rode hard and put away wet."


----------



## XBe02Drvr (Mar 11, 2021)

buffnut453 said:


> But not if the groundhogs have nose armor. Plus anything less than a 50 cal is useless from an armament perspective....at least according to one person on this thread.


That's okay. Right next to the .45 Kentucky in the cabinet there's a .50 cal Hawken, and I can always borrow my neighbor's .58 cal 1861 Springfield Rifle Musket or his .69 cal Brown Bess. (When my shoulder's not hurting too badly, that is!)


----------



## XBe02Drvr (Mar 11, 2021)

Glider said:


> Which part of:-
> 
> If you stall with little or no warning at low altitude, then there is an excellent chance you will hit the ground before you can recover.
> 
> Do you not understand?


What most nonfliers and some pilots don't understand is the huge gulf in response time between the pilot who is deliberately provoking a stall and and the unwary one who gets "ambushed" by a stall when he/she least expects it. With no behavioral or systemic warning of an impending stall, especially in a plane capable of "spectacular" departures, the "prompt" recovery specified by the test pilot may not be "prompt" enough to save the day.
"Don't give me a Pee Thirty Nine!"

Reactions: Agree Agree:
3 | Winner Winner:
1 | Informative Informative:
1 | Like List reactions


----------



## Ovod (Mar 11, 2021)

Graeme said:


> Not even loved by Bell?
> 
> View attachment 615688
> 
> ...


----------



## Ovod (Mar 11, 2021)

Graeme said:


> Not even loved by Bell?
> 
> View attachment 615688
> 
> ...



Interesting information on the above aircraft on Wikipedia: <i>Bell Airacobra I AH574</i>

It seems one reason the RAF weren't too fond of the P-39 was due to the length of its take-off run.

Reactions: Like Like:
2 | Like List reactions


----------



## XBe02Drvr (Mar 11, 2021)

Ovod said:


> Interesting information on the above aircraft on Wikipedia: <i>Bell Airacobra I AH574</i>


KUWULL!!


----------



## pbehn (Mar 11, 2021)

Ovod said:


> Interesting information on the above aircraft on Wikipedia: <i>Bell Airacobra I AH574</i>
> 
> It seems one reason the RAF weren't too fond of the P-39 was due to the length of its take-off run.


Brown loved it as a runabout, even after being used for deck landings. Warning to viewers, Please don't try this at home on your own P-39.

Reactions: Like Like:
1 | Like List reactions


----------



## P-39 Expert (Mar 11, 2021)

Right, Eric Brown and Chuck Yeager liked it. What did they know?


----------



## Shortround6 (Mar 11, 2021)

P-39 Expert said:


> Right, *Eric Brown* and Chuck Yeager liked it. What did they know?




Let me see, test pilot with thousands of hours in more planes than another pilot likes P-39 as personal runabout. 
Part of his career is assessing various aircraft for carrier landings (near stall) 
Yep, sure sounds like a ringing endorsement for giving the P-39 to low time pilots to me. 

I do like this part of the story though.

"
In March 1946, a visiting Bell Test pilot visited the Test establishment to oversee Laminar Flow experiments being conducted with Bell P-63 Kingcobras.

Just for a laugh I asked him to test my old Bell Airacobra, which I had been using for so many hops around the country. He took off, did one very quick circuit, and came back ashed-faced. 'I have never,' he said, 'flown in an aeroplane in such an advanced state of decay. This machine should be scrapped forthwith.' So, on 28th March, I went up for a last aerobatic session in her, then bade a sentimental farewell. The last laugh was on me.​AH574 was duly scrapped shortly afterward,[4] and Brown was later given a Fieseler Storch as a replacement"

What pilots with exceptional natural skills and/or thousands of hours of flight experience can/will tolerate in a plane might be way different than what is safe or desirable for run of mill pilots in the last stages of training or early deployment.

Reactions: Like Like:
5 | Like List reactions


----------



## Ovod (Mar 11, 2021)

P-39 Expert said:


> Right, Eric Brown and Chuck Yeager liked it. What did they know?



They may have both liked flying the P-39 (I'm sure we all would), but neither pilot actually flew combat in it, or would have ever wanted to do so. If I recall, Yeager flew P-51Ds, Brown - Grumman Wildcats.


----------



## P-39 Expert (Mar 11, 2021)

Wasn't the Bell test pilot commenting on that individual plane's "state of decay?" Brown's P-400 likely was worn out, it was one of the oldest P-39 models still flying, and doing test work at that. Planes do wear out.


----------



## pbehn (Mar 11, 2021)

P-39 Expert said:


> Right, Eric Brown and Chuck Yeager liked it. What did they know?


More than most in aviation they knew how to fly. Brown was noted to be exceptional at landing on carriers while training, 2,271 carrier landings with one crash, arrester hook didn't deploy, not noticed by deck crew. He loved the P-39 because for his use, hopping between airfields the tricycle landing gear meant he didn't need guiding in and out of places as you do with a tail dragger. Buying a Jimi Hendrix guitar doesn't give you the ability to play it with one hand while changing a string with the other Yeager and Brown were special aviators, if you need their ability to fly a plane in a training school you wipe out 99% of students at least.


----------



## pbehn (Mar 11, 2021)

Ovod said:


> They may have both liked flying the P-39 (I'm sure we all would), but neither pilot actually flew combat in it, or would have ever wanted to do so. If I recall, Yeager flew P-51Ds, Brown - Grumman Wildcats.


Brown also briefly flew Spitfires I believe from Wiki Following the loss of _Audacity_, Brown resumed operational flying, being seconded to Royal Canadian Air Force (RCAF) squadrons flying escort operations to USAAF Boeing B-17 Flying Fortress bombers over France. His job was to train them in deck-landing techniques, though the training took place on airfields.[Note 1] As a form of _quid pro quo_ he joined them on fighter operations.

Reactions: Informative Informative:
1 | Like List reactions


----------



## P-39 Expert (Mar 11, 2021)

pbehn said:


> More than most in aviation they knew how to fly. Brown was noted to be exceptional at landing on carriers while training, 2,271 carrier landings with one crash, arrester hook didn't deploy, not noticed by deck crew. He loved the P-39 because for his use, hopping between airfields the tricycle landing gear meant he didn't need guiding in and out of places as you do with a tail dragger. Buying a Jimi Hendrix guitar doesn't give you the ability to play it with one hand while changing a string with the other Yeager and Brown were special aviators, if you need their ability to fly a plane in a training school you wipe out 99% of students at least.


Their jobs were often evaluating airplanes. They both liked the P-39.


----------



## Shortround6 (Mar 11, 2021)

Could very well be true, but you brought in Brown as an example of experts who "liked" the P-39.
Even with his expertise he didn't realize how far from "normal" his particular P-39 was. 
Not a real dig against Brown, He didn't really have anything to compare it to. 
And that is point of the whole argument. _Context,_ just saying a pilot liked a plane doesn't tell us what they liked about, or what they didn't like, It doesn't tell us what planes they were comparing it to or why.

Reactions: Like Like:
1 | Winner Winner:
2 | Like List reactions


----------



## DerAdlerIstGelandet (Mar 11, 2021)

It’s the never ending story...

Reactions: Bacon Bacon:
1 | Funny Funny:
1 | Winner Winner:
1 | Like List reactions


----------



## Peter Gunn (Mar 11, 2021)

P-39 Expert said:


> Right, Eric Brown and Chuck Yeager liked it. What did they know?


In case you missed it (apparently you have), here's a quote by a REAL pilot that *I've grown to respect greatly*, _and pay close attention to the areas I've highlighted_:



XBe02Drvr said:


> Not *maintained; improved!! *It seems most P39s in combat trim, or even in training command, were flying around with CG at or near the aft limit, which may have itself been not conservative enough. A more forward CG increases the pitch-down tendency in a Departure From Controlled Flight (DFCF), reducing the probability of a flat spin. Given the concentration of mass in the core and the lack of polar inertia (a deliberate attempt to improve maneuverability), the impetus needed to get rotation started in a stall situation was pretty low. Add to that the easily blanked rudder and elevator configuration and you've got a potential booby trap for the inept or unwary pilot.* Intuitive fliers like Yeager or Brown would naturally fly through a stall with precise coordination, thus avoiding yawing into the asymmetric stall condition that sets up a spin*. *Eagles of that caliber would of course enjoy the very light stick force gradients and the light "feel" of the plane, and would have the finesse to not overcontrol it as a more ham-handed pilot would*.
> So get that CG forward, if you can, and make it a better flying machine!



Apropos of nothing, I remember my instructor demonstrating a stall (first time for me) in a Cessna 150, he started the nose up and I could hear the engine start to labor a bit, knew what was coming but man, that physical feeling of your stomach in your mouth so to speak. Yeah, scared the sh!t out of me.

Reactions: Like Like:
1 | Agree Agree:
1 | Like List reactions


----------



## special ed (Mar 11, 2021)

I suspect Brown's P-39 was even more aft CG with the tail hook which is still visible in the photo in the weeds.

Reactions: Agree Agree:
2 | Like List reactions


----------



## tyrodtom (Mar 11, 2021)

P-39 Expert said:


> Right, Eric Brown and Chuck Yeager liked it. What did they know?


I've read several books about and by Yeager.
He did say he liked , or would take on anybody in a P-39, but he added a qualifier to those statements you always leave out, BELOW 5000 FEET.

Reactions: Like Like:
1 | Agree Agree:
2 | Winner Winner:
1 | Informative Informative:
1 | Like List reactions


----------



## Koopernic (Mar 11, 2021)

XBe02Drvr said:


> What most nonfliers and some pilots don't understand is the huge gulf in response time between the pilot who is deliberately provoking a stall and and the unwary one who gets "ambushed" by a stall when he/she least expects it. With no behavioral or systemic warning of an impending stall, especially in a plane capable of "spectacular" departures, the "prompt" recovery specified by the test pilot may not be "prompt" enough to save the day.
> "Don't give me a Pee Thirty Nine!"



This is one of the key factors in the MCAS disaster.

A number of WW2 aircraft could have benefitted from stall warnings. I don’t think such devices existed, generally attributed to Leonard Green.


----------



## pbehn (Mar 11, 2021)

P-39 Expert said:


> Their jobs were often evaluating airplanes. They both liked the P-39.


Brown landed and took off a carrier in a P-39 it was never used for carrier operations. Brown frequently flew below the "book" stall speed, which is for competent pilots not exceptional ones. His next "mount" was a Storch which although a tail dragger was similar to a P-39 in all around visibility on the ground. Yaeger said words to the effect " I would have no problem going into combat in a P-39" well he wouldnt, he had the skill and awareness to keep himself alive, the top German aces managed to keep themselves alive when others didnt when outnumbered 6-1 by the end of the war that was more due to their ability than that of their aircraft because new pilots didnt last a single mission in many cases.

Reactions: Like Like:
2 | Agree Agree:
2 | Like List reactions


----------



## pbehn (Mar 11, 2021)

tyrodtom said:


> I've read several books about and by Yeager.
> He did say he liked , or would take on anybody in a P-39, but he added a qualifier to those statements you always leave out, BELOW 5000 FEET.


That's as I remember it, I believe he worked for Bell at the time.

Reactions: Informative Informative:
1 | Like List reactions


----------



## tyrodtom (Mar 11, 2021)

This may be a little off subject, but that happens a lot on this forum.
Last night I was reading a book I had just got about WW1 Pfalz aircraft.
It said the reason the Fokker DVII was so favored over the Pfalz or about any other then current aircraft was it had a stall that was gentle, with plenty of warning buffet before the stall.
That enabled even pilots without a lot of experience to fly it close to it's limits.
That's why they called it the aircraft that made good pilots out of mediocre pilots, and great pilots out of good ones.

Stall warning is a very important aspect of any aircraft's qualifications.

Reactions: Like Like:
3 | Agree Agree:
1 | Winner Winner:
3 | Informative Informative:
1 | Like List reactions


----------



## pbehn (Mar 11, 2021)

tyrodtom said:


> This may be a little off subject, but that happens a lot on this forum.
> Last night I was reading a book I had just got about WW1 Pfalz aircraft.
> It said the reason the Fokker DVII was so favored over the Pfalz or about any other then current aircraft was it had a stall that was gentle, with plenty of warning buffet before the stall.
> That enabled even pilots without a lot of experience to fly it close to it's limits.
> ...


I don't know about Germany, but in UK pilots weren't actually taught to fly in the present day sense until 1916, it was widely thought that a spin was impossible to recover from, those who did, did so by pure luck or innate skill. Actually teaching flying and not just take off circle and land started in 1916 with The Gosport System. When pilots are teaching themselves you need a very forgiving plane to let them do it. https://www.historiccroydonairport.org.uk/the-gosport-system-robert-smith-barry-and-pilot-training/


----------



## FLYBOYJ (Mar 11, 2021)

pbehn said:


> That's as I remember it, I believe he worked for Bell at the time.



Yeager never worked for Bell - He was a career Air Force officer, retired 1975

Reactions: Like Like:
2 | Like List reactions


----------



## XBe02Drvr (Mar 11, 2021)

Peter Gunn said:


> Apropos of nothing, I remember my instructor demonstrating a stall (first time for me) in a Cessna 150, he started the nose up and I could hear the engine start to labor a bit, knew what was coming but man, that physical feeling of your stomach in your mouth so to speak. Yeah, scared the sh!t out of me.


The first time the bottom falls out and your seat tilts forward and your stomach bumps your diaphragm, it's an attention getter, especially if you're a "feet solidly planted on Mother Earth" sort of person. I had some experience with gymnastics, high jumping, ski jumping, trampoline, sailing, and SCUBA diving before flying, so I was *somewhat *prepared for the sensation, but it still made an impression! After the first demonstration the instructor turned the plane over to me for the rest of the flight, then we worked on slow flight maneuvering, keeping the stall horn blowing at the same pitch (love those Cessna graduated pitch stall horns!) while perfecting aileron-rudder coordination, keeping the ball centered, and observing and internalizing the visual cues of even small amounts of yaw as the nose crept along the horizon. After a half hour of this, my instructor, a Master Chief Aviation Machinists Mate, (and former Naval Aviation Pilot [enlisted], before blood pressure took him off flight status and the standing offer of a commission expired)* said I could execute a stall on my own whenever I felt ready. My first one was straight ahead, real gentle, dull, boring, and an example of instructional technique was established I've tried to live up to ever since, in the air, in the water, and on the range.

*If you were an E9 Master Chief with a large family and 20+ years of service and 6 in grade, would you give that up to become an O1 Ensign with zero time in grade? Especially with retirement likely before you make JG? Like going from the top of the heap to the bottom.

Reactions: Like Like:
3 | Like List reactions


----------



## special ed (Mar 11, 2021)

Although I had experienced a stall as a teenage CAP cadet in an L-16, demonstrated by a Senior member, my first attempt later with a CFI wouldn't happen. I weighed 130 lb and the instructor about 140-145. The acft just wouldn't stall. It hung there, engine hammering until the CFI dropped the wing to simulate the stall. My first real stalls were later with a C-150 and another CFI. Although I soloed, finances kept from a Private license. I have received lots of stick time in the air with friends on different acft and with my best bud who was a CFI. He was always trying to get me back into full scale aviation (we flew models together). The only time I felt seat of the pants unsure was when he had me set up for a landing at an uncontrolled strip in his Grumman American (AA-1). At the time, I weighed about 175 and my buddy was 250. I know the bird CG was critical as I could lean forward and he would have to trim. Lean back and he trims again. The landing in question was after base leg and near the numbers it felt as though the acft wanted to throw me over my shoulder so I called for him to take it back. This ,however, was the only aircraft I could fly with thumb and first finger as I had read about when a kid.

Reactions: Like Like:
1 | Like List reactions


----------



## DerAdlerIstGelandet (Mar 11, 2021)

XBe02Drvr said:


> The first time the bottom falls out and your seat tilts forward and your stomach bumps your diaphragm, it's an attention getter, especially if you're a "feet solidly planted on Mother Earth" sort of person. I had some experience with gymnastics, high jumping, ski jumping, trampoline, sailing, and SCUBA diving before flying, so I was *somewhat *prepared for the sensation, but it still made an impression! After the first demonstration the instructor turned the plane over to me for the rest of the flight, then we worked on slow flight maneuvering, keeping the stall horn blowing at the same pitch (love those Cessna graduated pitch stall horns!) while perfecting aileron-rudder coordination, keeping the ball centered, and observing and internalizing the visual cues of even small amounts of yaw as the nose crept along the horizon. After a half hour of this, my instructor, a Master Chief Aviation Machinists Mate, (and former Naval Aviation Pilot [enlisted], before blood pressure took him off flight status and the standing offer of a commission expired) said I could execute a stall on my own whenever I felt ready. My first one was straight ahead, real gentle, dull, boring, and an example of instructional technique was established I've tried to live up to ever since, in the air, in the water, and on the range.



You are bringing back memories of my first stall instruction. 

I got off work, and went straight to the airfield, thinking we were going to work on some basic stuff. As soon as I walked into the office my instructor said today we are going to do stalls. My heart sank. He must have seen it because he said “You’ve been watching YouTube videos haven’t you?” He demonstrated the first one, and as he pulled the nose up so we were almost like a helicopter, I was looking for something to grab onto. The departure in a Cherokee (when done right, and coordinated is very docile). I was like “Thats it?”. But, yeah, the initial drop and nose over is a lil weird and takes getting used to. Other aircraft break differently. There, however, is a reason we train for them.

Reactions: Like Like:
1 | Like List reactions


----------



## GrauGeist (Mar 11, 2021)

Saying that a famous pilot (or two famous pilots) "like" a type really means nothing.

I like the Cessna 150...but that's not an endorsement. I like it, so what?

On the otherhand, I love the Ercoup - it's a nimble little ship, docile to handle and offers no surprises.
Of the broad range of civvies out there, I would choose the Ercoup any time, because I love it. That's an endorsement.

Reactions: Agree Agree:
1 | Like List reactions


----------



## buffnut453 (Mar 11, 2021)

I learned to fly at Speke Airport just outside Liverpool. We had a motley mix of Cessna 150s and a solitary 152 Aerobat. The biggest shock I got wasn't in stalling the 150s - they were pretty benign under most conditions. Stalling the 152 power on while pulling (limited) g was a different matter entirely. There was a sharp wing drop and all of a sudden, we were in a spin. Now...all that being said, the 152 was just a (slightly) souped-up 150, so it rapidly stabilized and spin recovery was straightforward. However, I remember the event vividly (it was 35 years ago now...eeek!) so, clearly, the experience made an impression.

Reactions: Like Like:
2 | Agree Agree:
1 | Like List reactions


----------



## GregP (Mar 11, 2021)

One more thing to say about Yeager (maybe Brown, can't say). When Chuck Yeager was trining to be combat pilot, he went through the various stages of flying in a primary trainer (like a Fairchild PT-19/23/26), basic trainer (like a Vultee BT-13/15), an advanced trainer (like a North American AT-6/SNJ), and a lead-In fighter trainer (like a weary P-39 or P-40, neither of which were ever the best fighters in whatever theater they were in ... unles they were the ONLY fighters around).

In Yeager's case, he trained on the P-39. The P-39 was, by far, the most powerful airplane he had flown to date, and he naturally loved in, especially since he survived it. Once he had flown other, better, first-line fighters, I seriously doubt he would have chosen the P-39 for a fighter mission over a P-47 / P-51. Now, to go out for a spin in a staion hack as local transportation, maybe he WOULD have chosen a P-39, I don't know. His autobiography says he flew a Soviet P-39 in an aerobatic display once disguised as a Soviet female pilot. None of that implies he thought the P-39 was a first-line fighter or that he would have chosen it for a mission or missions. It just says he liked it. My bet is he never or rarely flew it with no ammunition in it. If he did, he was VERY aware of the "edge of the razor" feeling you get in an airplane when the CG is too far aft, and treated it with kid gloves, so he again survived the Airacobra.

The P-39 was not a terrible airplane. It just wasn't a very good one though, if properly loaded and properly flown, it did perform decently well in a limited envelope of air combat. It just couldn't do it very high, very fast, or very far away from the takeoff point. The average P-39 that sat outside in the weather (which was MOST of them in all theaters) was probably lucky if it could get as fast as 360 mph. All the 398 mph stuff you read about was a factory-new airplane with a new/fresh engine and new/fresh prop flown by a test pilot VERY familiar with the P-39. It was not an airplane a novice pilot was likely to be able to pull around in a tight, close-to-stall dogfight turn low to the ground and survive in. You could do that in a P-38, a P-40, a P-47, and P-51 (with some practice), but the P-39 was not forgiving around the stall like the other were. All of them were much more resistant to spin entry from an inadvertent stall, particulary if you unloaded the wing quickly. The P-39 could and did rotate quite quickly. For that matter, a P-63 would do it, too, but was altogether a much better airplane than the P-39 ever thought of being.

It has been mentioned that the Bf 109 was good around the stall. It has automatic slats that extend when the airflow separates. They are unpowred and simply flop where they want to go. They DO produce a very high lift coefficient, but that is not their intended use. They were put there solely to keep the airflow over the ailerons attached through the stall, so the pilot could maintain roll control THROUGH THE STALL. That's all they were there for, to maintain control through the stall. If they actuated asymmetrically, they spoiled the aim, but once they were out, the pilot could re-acquire the sight picture and shoot, even through the stall. It is a primary reason why there are many people who think a Bf 109 can turn with a Spitfire ... because the pilot could be stalled and still be fighting with roll control. It's why Bf 109 pilots were comfortable in low-altutude turning fights - they KNEW their airplane would warn them aerodynamically before departing and snapping into the ground out of control. It gives you confidence when your plane has great stall manners and you KNOW that.

Reactions: Bacon Bacon:
1 | Like Like:
4 | Like List reactions


----------



## gumbyk (Mar 11, 2021)

P-39 Expert said:


> Their jobs were often evaluating airplanes. They both liked the P-39.


Brown liked it "as a runabout"
Hell, I like a Cessna 172 as a runabout, doesn't mean its any good as an aerobatic aircraft, or have its vices when at the edge of its envelope. I've flown one at the very corner of the CG envelope, and I wouldn't want to have encountered an unintentional stall.

Reactions: Like Like:
2 | Like List reactions


----------



## P-39 Expert (Mar 11, 2021)

GregP said:


> One more thing to say about Yeager (maybe Brown, can't say). When Chuck Yeager was trining to be combat pilot, he went through the various stages of flying in a primary trainer (like a Fairchild PT-19/23/26), basic trainer (like a Vultee BT-13/15), an advanced trainer (like a North American AT-6/SNJ), and a lead-In fighter trainer (like a weary P-39 or P-40, neither of which were ever the best fighters in whatever theater they were in ... unles they were the ONLY fighters around).
> 
> In Yeager's case, he trained on the P-39. The P-39 was, by far, the most powerful airplane he had flown to date, and he naturally loved in, especially since he survived it. Once he had flown other, better, first-line fighters, I seriously doubt he would have chosen the P-39 for a fighter mission over a P-47 / P-51. Now, to go out for a spin in a staion hack as local transportation, maybe he WOULD have chosen a P-39, I don't know. His autobiography says he flew a Soviet P-39 in an aerobatic display once disguised as a Soviet female pilot. None of that implies he though the P-39 was a first-line fighter or that he would have chosen it for a mission or missions. It just says he liked it. My bet is he never or rarely flew it with no ammunition in it. If he did, he was VERY aware of the "edge of the razor" feeling you get in an airplane when the CG is too far aft, and treated it with kid gloves, so he again survived the Airacobra.
> 
> ...


Thanks for your opinion on what Chuck Yeager thought. Yeager's exact quote was that he "would gladly fly that little plane off to war anytime" and this was well after WWII when he was in his 60s. He also said "Those people never flew a P-39" when asked about tumbling and other supposed handling problems.
Regarding your opinion of the performance of a well used P-39, all planes in combat were in that condition. Make accurate comparisons when stating your opinions.


----------



## pbehn (Mar 11, 2021)

FLYBOYJ said:


> Yeager never worked for Bell - He was a career Air Force officer, retired 1975


Badly worded on my part. As I remember it, it was around when he broke the sound barrier, journalists and writers speaking to a famous aviator who just broke the sound barrier in a Bell aircraft asking typical questions " which planes did you fly", "which was the best then the NA P-51 or the BELL P-39? An aviation question that demanded diplomacy.


----------



## pbehn (Mar 11, 2021)

buffnut453 said:


> I learned to fly at Speke Airport just outside Liverpool. We had a motley mix of Cessna 150s and a solitary 152 Aerobat. The biggest shock I got wasn't in stalling the 150s - they were pretty benign under most conditions. Stalling the 152 power on while pulling (limited) g was a different matter entirely. There was a sharp wing drop and all of a sudden, we were in a spin. Now...all that being said, the 152 was just a (slightly) souped-up 150, so it rapidly stabilized and spin recovery was straightforward. However, I remember the event vividly (it was 35 years ago now...eeek!) so, clearly, the experience made an impression.


The first time I controlled a two wheeled slide going through Redgate corner at Donnington Park I was completely elated. It made the dozen times I had failed and bounced up the track on my ass or head worthwhile.

Reactions: Like Like:
2 | Like List reactions


----------



## DerAdlerIstGelandet (Mar 11, 2021)

P-39 Expert said:


> Make accurate comparisons when stating your opinions.



You should follow your own advice.

Reactions: Bacon Bacon:
1 | Like Like:
1 | Agree Agree:
1 | Winner Winner:
1 | Like List reactions


----------



## XBe02Drvr (Mar 11, 2021)

P-39 Expert said:


> Yeager's exact quote was that he "would gladly fly that little plane off to war anytime" and this was well after WWII when he was in his 60s


...and looking back through his rose tinted retrospectroscope.


----------



## pbehn (Mar 11, 2021)

XBe02Drvr said:


> ...and looking back through his rose tinted retrospectroscope.


There were Russian aces who would agree with him, but of the 4,000+ P-39s sent to Russia how many pilots made ace and how many were shot down. I loved the first bike I raced a Suzuki X7, it could out brake and out turn anything I was ever involved with, but that was mainly because it couldn't do more than 110MPH, given more power it wouldn't have been better, it would have been a death trap, cornering over 90MPH was a real experience, you could feel the frame twisting, great memories though even though I never won a race.


----------



## XBe02Drvr (Mar 11, 2021)

GrauGeist said:


> I like the Cessna 150...but that's not an endorsement. I like it, so what?


I *like* the Cessna 150/152. That *IS* an endorsement. I think it's the all-around best civil aviation primary trainer out there. (Not including any post-1995 additions to the field) It's able to perform and demonstrate pretty much all the basic factors of aerodynamics, including spins, and doesn't "hide" some of them as some other "trainers" do (I'm looking at you, Cherokee!)
It's easy to fly safely, but makes you work to fly it truly precisely, as a trainer should. Rugged enough to survive many thousands of hours of student abuse, yet light enough to get decent performance from a frugal 100 or 110 hp engine that will go 1800 or 2000 hours TBO, and then won't cost 2/3 the plane's value to overhaul.
My old pal, the T34, will probably take offense at this, but I think the 150/152 is better as a civil aviation trainer. The T34 was designed to train military pilots for the jet age, so Beech went out of their way to disguise torque and P factor, and to minimize pitch change with power as much as they could. The thrust line is canted down and to the right to a noticable degree, which is why an early Bonanza cowling doesn't fit on a T34, despite the identical engine and prop.
Anyway, that's my story, and I'm sticking to it.

Reactions: Like Like:
4 | Like List reactions


----------



## fubar57 (Mar 11, 2021)

This is the only airplane I have flown, last year. Soloed after 2300hrs and was pretty shaky on landing. No stalls though

Reactions: Bacon Bacon:
1 | Like Like:
3 | Funny Funny:
5 | Winner Winner:
2 | Like List reactions


----------



## pbehn (Mar 11, 2021)

fubar57 said:


> This is the only airplane I have flown, last year. Soloed after 2300hrs and was pretty shaky on landing. No stalls though
> 
> View attachment 615793​


With those stubby wings and no flaps, that is great control.


----------



## buffnut453 (Mar 11, 2021)

But does it have nose armour?


----------



## FLYBOYJ (Mar 11, 2021)

Or IFF in the tail?


----------



## nuuumannn (Mar 11, 2021)

XBe02Drvr said:


> As for "any WWII fighter plane", no other fighter of the time had as low a polar inertia as the P39. No other plane had as high a percentage concentration of its mass amidships as the P39, making it the least resistant to rotation in a stall situation of all of them. No other fighter (except possibly the Merlin Mustang in some cases) did as much flirting with its aft CG limit. Both of these features (low polar inertia and aft CG) are stability detractors, increasing both the probability and the severity of a departure in a stall situation. Add to that, the "light" touch on the controls and the jerky overcontrolling of a panicked inept pilot, and you've got a potential deathtrap. Not the type of "honest flying airplane" to instill confidence in nugget aviators and their instructors.



Geepers, makes the Boulton Paul Defiant, with its weight concentrated centrally, look good. Brown on the Daffy: "The Defiant exhibited good stability characteristics, very suitable for a night fighter. In cruising flight this positive stability was accompanied by good harmony of the controls, which were all moderately light and effective, though not up to the standard of the Hurricane."

He commented that it had undesirable stall characteristics because there was little or no impending warning of the stall (ahem), and ended with "The Defiant will never be remembered as a great operational aeroplane, but it deserves to be remembered as an aircraft with almost no flying vices."



Koopernic said:


> This is one of the key factors in the MCAS disaster.



That, and like the Airacobra, some wayward design choices that made it a bit of a dog, hence the MCAS in the first place. And that doesn't include the change in focus of the company, the poor training of aircrew, the fast-tracking of certification to meet in-service dates to match its opposition... A litany of problems far greater than the aircraft itself.



fubar57 said:


> This is the only airplane I have flown, last year. Soloed after 2300hrs and was pretty shaky on landing. No stalls though



But ample stall warning though, it has a built-in stick shaker.

Reactions: Agree Agree:
1 | Like List reactions


----------



## XBe02Drvr (Mar 12, 2021)

nuuumannn said:


> Geepers, makes the Boulton Paul Defiant, with its weight concentrated centrally, look good.


At least it had a big chunk of metal in its forecastle to drag the nose down when it went ballistic. Makes a big difference in stall recovery.

Reactions: Like Like:
1 | Agree Agree:
1 | Like List reactions


----------



## GregP (Mar 12, 2021)

My apologies for loosely quoting Yeager, which I read in 1985 and have not read since then. While I generally have a decent memory, it WAS 35 years ago that I read it. My recollection of his autobiography can be summed up in this sentence, "Hi, I'm Chuck Yeager and you're not." Hence, my lack of a second perusal of it. Perhaps his attitude is what General Momyer didn't like when he went to Viet Nam.

If he truly would fly the P-39 off to war "anytime," he's in a very small minority of WWII fighter pilots. Most of them would have happily traded in a P-39 for almost anything else that ran. There's a reason for that, but I'm sure you don't want to hear it again, so I'll oblige.

Cheers to you.

Reactions: Like Like:
1 | Like List reactions


----------



## Koopernic (Mar 12, 2021)

XBe02Drvr said:


> At least it had a big chunk of metal in its forecastle to drag the nose down when it went ballistic. Makes a big difference in stall recovery.



Do you think some of these handling issues were solved or tamed in the P63? Possibly mainly a longer tail.


----------



## XBe02Drvr (Mar 12, 2021)

Koopernic said:


> Do you think some of these handling issues were solved or tamed in the P63? Possibly mainly a longer tail.


Don't know. Haven't heard so much trash talk about the P63. Maybe they rearranged things and got the CG off the aft limit. As long as the added weight is compensated for CG wise, a longer tail would certainly help, improving rudder and elevator moment and reducing the blanking effect in a spin.


----------



## GregP (Mar 12, 2021)

I have heard from people who fly a P-63 today that is handles very well and flies very well. These guys are NOT doigfighting with it, so their comments really don;t amount to a fighter flight report. I haven't seen many WWII P-63 flight reports, but the P-63 was supposed to address the wekanesses of the P-39. It was fast, climbed well, and rolled and turned well. But I do not know if it had CG issues if the ammunition was empty.

But, I look at it this way ... they didn't believe the P-39 would tumble during WWII and the P-63 was designed during WWII. It was sometime after the war that the guys managed to get a P-39 model to tumble in a wind tunnel when ballasted to aft CG. That said, I can't recall exactly WHEN this test was done, but it well after the P-63 was flying. So, I'm not sure Bell had any incentive to corect a condition they steadfastly maintained didn't exist.

In my case, the jury is still out on the P-63 "bad habits," but the P-63 seems like a quantum leap forward from the P-39 if you read about it a bit. Altogether, it seems like maybe a decent airplane that we simply didn't want.


----------



## XBe02Drvr (Mar 12, 2021)

GregP said:


> the P-63 seems like a quantum leap forward from the P-39 if you read about it a bit. Altogether, it seems like maybe a decent airplane that we simply didn't want


I think the legacy of the P39 was just a little too much to overcome. It wasn't a P51, so why bother?

Reactions: Agree Agree:
3 | Like List reactions


----------



## P-39 Expert (Mar 12, 2021)

XBe02Drvr said:


> I think the legacy of the P39 was just a little too much to overcome. It wasn't a P51, so why bother?


Why bother? Because the P-39 was available for combat at the beginning of WWII. The P-51 wasn't. Along with the P-40 and F4F it was all we had. Could have easily weighed 7160lbs and outclimbed the A6M2 as well as being 40mph faster. But no, had to have those 30cals in the wings or the war was lost.


----------



## FLYBOYJ (Mar 12, 2021)

P-39 Expert said:


> Why bother? *Because the P-39 was available for combat at the beginning of WWII*. The P-51 wasn't. Along with the P-40 and F4F it was all we had. Could have easily weighed 7160lbs and outclimbed the A6M2 as well as being 40mph faster. But no, had to have those 30cals in the wings or the war was lost.


So was the P-38 which replaced the P-39 in the SWP Theater in late 42'. Why was that???


----------



## P-39 Expert (Mar 12, 2021)

FLYBOYJ said:


> So was the P-38 which replaced the P-39 in the SWP Theater in late 42'. Why was that???


Not understanding your question, did you mean to say the P-38 was available for combat at the beginning of WWII? If it was, why wasn't it used? If I misunderstood the meaning of your question please explain.


----------



## pbehn (Mar 12, 2021)

P-39 Expert said:


> Why bother? Because the P-39 was available for combat at the beginning of WWII. The P-51 wasn't. Along with the P-40 and F4F it was all we had. Could have easily weighed 7160lbs and outclimbed the A6M2 as well as being 40mph faster. But no, had to have those 30cals in the wings or the war was lost.


The war started in September 1939. The USA was involved from December 1941. While The UK was packing off its P-39s to Russia the first Mustang MkIs ( P-51A) were arriving, not all arrived because the US, understandably took them for their own needs.

Reactions: Like Like:
2 | Winner Winner:
1 | Like List reactions


----------



## Glider (Mar 12, 2021)

P-39 Expert said:


> Why bother? Because the P-39 was available for combat at the beginning of WWII. The P-51 wasn't. Along with the P-40 and F4F it was all we had. Could have easily weighed 7160lbs and outclimbed the A6M2 as well as being 40mph faster. But no, had to have those 30cals in the wings or the war was lost.



Your definition of the beginning of WW2 and being combat ready is so far from reality

Timeline
First Order placed I believe in August 1939 (of a version everyone agreed wasn't suitable for combat) War breaks out when Germany invades Poland 1 Sept 1939.
*Result* P39 not ready from the beginning of WW2

Combat Ready
The RAF ones were rejected almost as soon as they received them for a host of basic fundamental problems, not just performance. It certainly wasn't ready for combat as late as August 1941. 
The P39 probably holds the record for being the only combat aircraft withdrawn from operations before the Press day to announce its arrival.

Edit
Your fantasy about the weight of the P39 is staggering in the breadth of its imagination

Reactions: Like Like:
2 | Winner Winner:
1 | Like List reactions


----------



## FLYBOYJ (Mar 12, 2021)

P-39 Expert said:


> Not understanding your question, did you mean to say the P-38 was available for combat at the beginning of WWII? If it was, why wasn't it used? If I misunderstood the meaning of your question please explain.


YES!!! It was sent to the SWP and *replaced* the P-39s being flown by the 39th and 9th FS, V Fighter Command. So to be crystal clear, why was the P-39 replaced???? (In your opinion)


----------



## Peter Gunn (Mar 12, 2021)

P-39 Expert said:


> Why bother? Because the P-39 was available for combat at the beginning of WWII. The P-51 wasn't. Along with the P-40 and F4F it was all we had. Could have easily weighed 7160lbs and outclimbed the A6M2 as well as being 40mph faster. But no, had to have those 30cals in the wings or the war was lost.


Actually, with a little forethought, the USAAF could have been operating Allison Mustangs by January 1942. I mean, it's no more of a stretch than the magical climb/speed the P-39 could attain if several criteria were met... theoretically.

Reactions: Like Like:
1 | Like List reactions


----------



## P-39 Expert (Mar 12, 2021)

FLYBOYJ said:


> YES!!! It was sent to the SWP and *replaced* the P-39s being flown by the 39th and 9th FS, V Fighter Command. So to be crystal clear, why was the P-39 replaced???? (In your opinion)


My opinion, because it had a hard time intercepting Japanese bombers at 18000-22000ft and had a hard time cruising at over 18000ft, in both cases while carrying a 110gal drop tank. These P-39D/F/K/L models in 1942 weighed around 7800lbs clean and another 750lbs with the ever present drop tank for a total of around 8550lbs, all powered by an 1150hp engine. This was insanely heavy in comparison with other contemporary fighters with comparable engines. 

These 1942 P-39s could have easily weighed 7160lbs clean and 7900lbs with drop tank. According to AHT the P-39D weighed 5525lbs empty, add a modified load of 1669lbs (pilot 160lbs, oil 70lbs, 120gal fuel 720lbs, 37mm cannon 300lbs, twox50calMG 275lbs and armor plate/glass of 130lbs without the nose armor, oxygen 10lbs, gunsight 4 lbs). 5525lbs empty + 1669lbs load = 7194lbs. Deduct 34lbs from "armament provisions" since without the 30cal wing guns their gun mounts, chargers, heaters and ammunition boxes aren't needed.  Gross weight 7160lbs. 

The P-39C weighed 7075lbs gross (only 85lbs difference) and had a top speed of 379mph and initial climb rate of 3720fpm as compared to 2720fpm for a P-39K. Performance increase would have enabled these lighter P-39s to handle Zeros/Oscars for the foreseeable future until Nov/Dec when the improved M/N/Q models were in production. 

P-38s could have been sent to Europe to escort 8thAF bombers, if they had been available.


----------



## Thumpalumpacus (Mar 12, 2021)

lol

Reactions: Like Like:
1 | Funny Funny:
1 | Winner Winner:
3 | Like List reactions


----------



## fubar57 (Mar 12, 2021)

Love that song

Reactions: Like Like:
1 | Like List reactions


----------



## Thumpalumpacus (Mar 12, 2021)

fubar57 said:


> Love that song



And it's so apt for this topic, too!


----------



## DerAdlerIstGelandet (Mar 12, 2021)

P-39 Expert said:


> My opinion, because it had a hard time intercepting Japanese bombers at 18000-22000ft and had a hard time cruising at over 18000ft, in both cases while carrying a 110gal drop tank. These P-39D/F/K/L models in 1942 weighed around 7800lbs clean and another 750lbs with the ever present drop tank for a total of around 8550lbs, all powered by an 1150hp engine. This was insanely heavy in comparison with other contemporary fighters with comparable engines.
> 
> These 1942 P-39s could have easily weighed 7160lbs clean and 7900lbs with drop tank. According to AHT the P-39D weighed 5525lbs empty, add a modified load of 1669lbs (pilot 160lbs, oil 70lbs, 120gal fuel 720lbs, 37mm cannon 300lbs, twox50calMG 275lbs and armor plate/glass of 130lbs without the nose armor, oxygen 10lbs, gunsight 4 lbs). 5525lbs empty + 1669lbs load = 7194lbs. Deduct 34lbs from "armament provisions" since without the 30cal wing guns their gun mounts, chargers, heaters and ammunition boxes aren't needed. Gross weight 7160lbs.
> 
> ...



So it was ready for combat, but it wasn’t ready...


----------



## FLYBOYJ (Mar 12, 2021)

P-39 Expert said:


> My opinion, because it had a hard time intercepting Japanese bombers at 18000-22000ft and had a hard time cruising at over 18000ft, in both cases while carrying a 110gal drop tank. These P-39D/F/K/L models in 1942 weighed around 7800lbs clean and another 750lbs with the ever present drop tank for a total of around 8550lbs, all powered by an 1150hp engine. This was insanely heavy in comparison with other contemporary fighters with comparable engines.
> 
> These 1942 P-39s* could have* easily weighed 7160lbs clean and 7900lbs with drop tank. According to AHT the P-39D weighed 5525lbs empty, add a modified load of 1669lbs (pilot 160lbs, oil 70lbs, 120gal fuel 720lbs, 37mm cannon 300lbs, twox50calMG 275lbs and armor plate/glass of 130lbs without the nose armor, oxygen 10lbs, gunsight 4 lbs). 5525lbs empty + 1669lbs load = 7194lbs. Deduct 34lbs from "armament provisions" since without the 30cal wing guns their gun mounts, chargers, heaters and ammunition boxes aren't needed. Gross weight 7160lbs.
> 
> ...



"Could have, would have" Just face it, the P-39 in the SWP was just an inferior aircraft when compared to the P-38 and that will include the later model P-39s. Look at the performance of the 2 units I posted, what they accomplished with the P-39 and then their records with the P-38.


----------



## Thumpalumpacus (Mar 12, 2021)

Any improvements that don't increase the a/c's endurance are going to be incomplete, because you'll be burning a lot of fuel to get to those Bettys at 20k. In that circumstance, I'm betting combat power is going to get you to bingo fuel PDQ.

Reactions: Agree Agree:
2 | Like List reactions


----------



## P-39 Expert (Mar 12, 2021)

FLYBOYJ said:


> "Could have, would have" Just face it, the P-39 in the SWP was just an inferior aircraft when compared to the P-38 and that will include the later model P-39s. Look at the performance of the 2 units I posted, what they accomplished with the P-39 and then their records with the P-38.


Look at the performance graphs for the contemporary P-38 and P-39. P-39N and P-38F/G.


----------



## GregP (Mar 12, 2021)

For the P-39K, there was a 20 gallon allowance for takeoff not avilable in flight. It would burn 41 gallons getting fro S.L. to 25,000 feet.

So, we start off with 175 gal (195 - 20) and we burn 41 gals to get to 25,000 feet from sea level, leaving 134 gallons for the mission starting at climb airspeed and 25,000 feet. I'm assuming you want to be above the Betty bombers and going faster than climb speed.

If you cruise at max continuous, you have 1.3 hours before you are out of fuel. If you go to combat power, you have 1 hour before you run out of fuel, but you can't run cxombat pwoer for longer then eiher 5 minutes or 15 minutes, depending on who you believe. So, you have somehwere between 1 hour and 1.3 hours before you are out of fuel.

I'm assuming you really don't want to run out of fuel, so you start up, takeoff and get to maybe 21,000 feet and have something like 1hr 20 min to 1 hr 40 min to play with before you are out of fuel. Therefore, you limit your mission to something like 45 min to 1 hr and cruising at less the max continuous, and carefully plan our fuel burn. Basically, it flies a small bit longer than a Bf 109, which was the world standard for a short-range fighter. That means that in the Pacific, it was basically for local operations only and would not be considered for missions very far away.

So, while it wasn't uselsss, it also wan't going to ever be a plane selected for a 2.0 - 2.5-hour mission. If you cruise at 200 mph, that means you aren't ever going to get more than something like 100 miles from your home airfield. That doesn't offer much in the way of useful operations in the Pacific Ocean ... but, that's exactly where we sent quite a few of them. Makes me wonder a bit about the wisdom of our procurement policies.

Reactions: Like Like:
1 | Like List reactions


----------



## GregP (Mar 12, 2021)

For the P-39K, there was a 20 gallon allowance for takeoff not avilable in flight. It would burn 41 gallons getting fro S.L. to 25,000 feet.

So, we start off with 175 gal (195 - 30) and burn 41 gals to get to 25,000 feet, leaving 134 gallons for the mission starting at climb speed at 25,000 feet. I'm assuming you want to be above tbe Betty bombers and going faster than climb speed. Max continuous burns 103 gph and combat power burns 132 gph. So, if we need to go fast to catch Betty bombers, our mission is somewhere between 1.0 and 1.3 hours untl we're out of fuel. Since we don't really want to BE out of fuel, I'd say we're looking at about a 45-minute mission and ecomony cruise back home. That doesn't allow for the P-39 to be selected for many mnissions other than extremely local, say 100 miles away more or less.

No wonder it got replaced in the Pacific Ocean areas ... there just seemingly weren't that many missions it could be assigned to perform, even if we just look at range. Nevermind hauling some bombs. You could apparently haul up to 500 pounds of bombs, but then you wouldn't have the belly tank and you lose 75 gallons of fuel. So, the target better be CLOSE, slightly more than the end of the runway, but not too much farther than beyond visual distance from the runway overrun or ocean, which ever was closer.

Reactions: Like Like:
1 | Like List reactions


----------



## P-39 Expert (Mar 12, 2021)

So a P-39K/L with 120 gallons internal and a 75 gallon drop tank has "a bit" more endurance than a 109 with 88 gallons? 

You're double counting the fuel used for climb. Either use the 20gal takeoff reserve that gets you to 5000' or use the 41gal to 25000', but not both.

And fuel burn at 25000ft at max continuous power (2600rpm) is only 54gph, not 103gph so combat at 25000' would burn about 62gph.

Using 41gal to climb to 25000ft, deduct reserves of 21gal for 20min combat at 25000ft and 10gal for 20min landing reserve leaves you 123gal using 54gph at 25000ft for a patrol endurance of 2.3hrs or 2hrs 18min. 

Using the 20gal reserve for takeoff and climb to 5000ft, deduct the 21gal combat reserve and the 10gal landing reserve leaving 144gal using 54gph for a patrol endurance of 2.7hrs or 2hrs 42min. Deduct the additional 15 min to climb from 5000ft to 25000ft and you have 2hrs 27min. 

Take your pick, 2hrs 18min or 2hrs 27min. Nine minutes difference. 

Now after September/October 1942 there was radar at Port Moresby. Not ineffective Australian radar hundreds of miles away, but local radar at PM. In theory patrol with a drop tank was no longer necessary, planes could be ready and waiting for interception. Upon detection of incoming bombers clean P-39s could be launched with 120gal internal fuel. Deduct the 20gal reserve for takeoff, the 21gal combat reserve and the 10gal reserve for landing and 69gal were available for cruise at 25000ft at 54gph gave 1.3hrs or 1hr 18min, plenty of time to intercept incoming bombers.

Normal medium bomber/transport escort missions lasted a little over 3hrs at around 15000'.


----------



## pbehn (Mar 12, 2021)

Peter Gunn said:


> Actually, with a little forethought, the USAAF could have been operating Allison Mustangs by January 1942. I mean, it's no more of a stretch than the magical climb/speed the P-39 could attain if several criteria were met... theoretically.


Shortly (end December 1941) after war was declared by Germany on USA there were circa 150 Mustang Mk Is in UK, using the trade definition of "free on board" that is somewhere between the hold of a vessel in Liverpool and an airfield in England. Mustang MkIs were operational in squadron service by April 1942 so it isn't a giant leap to suggest the USA could have had them operational 3 months earlier. With all these things there is a question of what things mean, receiving 150 aircraft doesn't mean you can fly them the next day against the enemy, pilots and ground crew need to be trained, in fact with the Mustang MkI the first thing was to decide what to do with it, but then you need to find out what it can do.

Reactions: Agree Agree:
1 | Like List reactions


----------



## FLYBOYJ (Mar 12, 2021)

P-39 Expert said:


> Look at the performance graphs for the contemporary P-38 and P-39. P-39N and P-38F/G.


I have - and at the end of the day the P-38 was still the better fighter and outperformed the P-39 in combat, THAT'S HISTORY! But since you like to slant information and want to talk charts, look at the performance graphs for the P-38L and the P-39N. Case closed.


----------



## XBe02Drvr (Mar 12, 2021)

FLYBOYJ said:


> at the end of the day the P-38 was still the better fighter and outperformed the P-39 in combat


And even if their performances were identical, the P38 was the better machine because of its range. P39 just wasn't suitable for anything beyond interception and local air superiority.

Reactions: Agree Agree:
2 | Like List reactions


----------



## FLYBOYJ (Mar 12, 2021)

XBe02Drvr said:


> And even if their performances were identical, the P38 was the better machine because of its range. P39 just wasn't suitable for anything beyond interception and local air superiority.



Agree, but when discussing the P-39 in the SWP, I have a problem using "air superiority" in the same sentence.


----------



## SaparotRob (Mar 13, 2021)

I think the point XBe02Drvr was making was: 
By the time they fixed the P-39 and made it a P-63, the Mustang was available. Why bother with the P-63?

Reactions: Agree Agree:
1 | Like List reactions


----------



## SaparotRob (Mar 13, 2021)

Hey, we fixed the P-39! Make them P-63’s! 
It still didn’t work.


----------



## Glider (Mar 13, 2021)

SaparotRob said:


> I think the point XBe02Drvr was making was:
> By the time they fixed the P-39 and made it a P-63, the Mustang was available. Why bother with the P-63?



Which of course, is why the USAAF didn't bother with the P63

Reactions: Agree Agree:
1 | Like List reactions


----------



## wuzak (Mar 13, 2021)

P-39 Expert said:


> P-38s could have been sent to Europe to escort 8thAF bombers, if they had been available.



They were in mid 1942, but soon moved to support the invasion of Northern Africa for Operation Torch


----------



## XBe02Drvr (Mar 13, 2021)

FLYBOYJ said:


> Agree, but when discussing the P-39 in the SWP, I have a problem using "air superiority" in the same sentence.


The mission, not the performance. "Air inferiority" as a label just doesn't have the required cachet!

Reactions: Funny Funny:
3 | Informative Informative:
1 | Like List reactions


----------



## BiffF15 (Mar 13, 2021)

XBe02Drvr said:


> And even if their performances were identical, the P38 was the better machine because of its range. P39 just wasn't suitable for anything beyond interception and local air superiority.



And I would add, giving fledgling fighter pilots time in something more powerful than an T-6...

The bigger question is how many more pages of round about before this thread is closed as well.

Cheers,
Biff

Reactions: Like Like:
1 | Winner Winner:
2 | Like List reactions


----------



## DerAdlerIstGelandet (Mar 13, 2021)

I think its time. At some point the abuse has to stop.

Reactions: Bacon Bacon:
1 | Like Like:
3 | Agree Agree:
1 | Like List reactions


----------

