SHOULD the P39 have been able to handle the Zero? Was it training or performance?

Good point!
Send all your overweight pilots to the P-39s!

P-39 Expert said:

It did have a two stage supercharger, the first in any production combat plane. Didn't seem to be as efficient as others. Look at the performance graphs, I stand by my statement about the P-39 being faster at all altitudes.

Regarding the P-40, it had the same engine as the P-39 and weighed 750# more (8400-7650). There is no physical way possible for the P-40 to have the same performance in climb or level speed. Physically impossible. Merlin P-40 was faster than the Allison P-40, but no faster then the P-39.

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The F4F was a fat porker of an airplane. It would need a boat load more power to equal the P-39 in speed. However when turning at altitude (over 20,000ft?) it had a lower wing loading due to it's 20% bigger wing, it also had a lower power loading due the engine making 150-200more hp at these higher altitudes.
P-40F was as fast as a P-39 (pre K) at these altitudes and climbed better, generally 150-200fpm better which doesn't sound like much but when you are at 1500fpm and dropping to 530-300fpm of climb it is actually quite substantial.
The P-40F was good for several thousand more feet of altitude than than the Aircobras with 8.80 supercharger gears.
Early P-51s could run away and hide from a P-39 but their climb rate was pathetic at high altitudes using the same basic engine.

Part of the problem with comparing the two stage R-1830 and a single stage Allison (or Merlin) is that the R-1830 had a cooling problem.
The Supercharger may well have been inefficient but the R-1830 was restricted to 2550rpm in high gear compared to the 2700rpm it used in neutral or low gear. What combat pilots did in combat I don't know but test figures have to be looked at with that in mind. Air cooled engines, with very few exceptions, do not take kindly to over boosting.
The P & W supercharger was also designed when the US was using or planning on 100/100 fuel, not 100/125 or 100/130.
I don't know if the intercooler wasn't big enough or if the cooling fins on the cylinders weren't big enough.
Please note the early R-1830s, the early Wright 1820s and the Wright R-2600s NEVER got WEP ratings.
Later higher powered versions all got extensive modifications.

P-39 Expert said:

The 37mm cannon was better than most give it credit for. Yeager said the 37mm "had some trajectory" and was like "throwing a grapefruit". But the trajectory was not that bad inside the effective air to air gunnery range. Inside of about 400 yards the difference in the drop of the .50 caliber MGs and the 37mm cannon was negligible so you could fire all three at once. One strike from the 37mm cannon was usually deadly for anything it hit. Outside of 400 yards you were not likely to hit anything anyway. .

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It is not so much the trajectory as the time of flight requires different amounts of lead, in deflection shooting. Not a big problem if you are shooting almost stationary targets on the ground/water. Or slow moving bombers but against maneuvering fighters? 300mph airplane moves 44ft in 1/10 of a second.
That and the slow rate of fire made getting hits on fleeting targets very difficult.

P-39 Expert said:

P-39N in production between December '42 and April '44 was faster and climbed faster at all altitudes than the Spitfire V. The Spitfire IX was superior in speed and climb to the P-39N and entered full series production about the same time. The comparison I'm making is between the P-39N and the German fighters. Everyone else seems to have me in an argument over the Spitfire.

Regarding fuel, the P-39N carried 120 internal and the Spitfire carried 100 US gallons. During N production the Russians requested that we start deleting the wing guns from the factory and reducing internal fuel capacity. The N and Q gradually reduced capacity to as little as 86 gallons. The wing guns stayed until the late Q models. Apparently less fuel and no wing armament worked for them.

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excusing the typo of the production date (N production ended in APril '43)

we are back to repeating ourselves over the P-39s fuel capacity and performance. You don't get both the 120 gal fuel capacity and the the high rate of climb. Pick one.

The argument with the Spitfire is your claim that the P-40N could out climb everything but a Spitfire MK IX and your rather absurd claim that the Spitfire IX wasn't in full production until very late 1942 ( I guess the 4 squadrons at Dieppe in Augs were just using dozens of the prototype MK IXs?).

Against the much older MK V your one test P-39N may be technically ahead, but not by much, if any, at certain altitudes and not enough to make a real difference even at 20-25,000ft.

There was no gradually reduced capacity to as little as 86 gallons. you either had the full suite of 12 fuel cells with 120 gallons or you had the 8 tank suite of 87 gallons. The one gallon difference can be written off as a difference in translations or counting full fuel vs usable fuel.
Some loadings of the P-39 count 104 gallons of fuel but that is simply not filling the 120 gallon tanks all the way. Early P-51 loadings show 105 gallons of fuel "normal" and 180 gallons as overload. There were never 105 gallon tanks. Same with some P-40 loadings and many navy weight charts.

Please note that a full set of self-sealing fuel tanks for the P-39 weighed close to 290lbs so taking out the 4 smallest tanks/cells with the worst capacity to weight ratio is going to save a lot more weight than just the 33 gallons of fuel. The self sealing material was heavy. The production of the 87 gallon P-39s coincided with several light weight P-40 projects, culminating in the P-40N. Some of the P-40Ls had done the simple strip routine, yank a pair guns, yank some armor, yank a fuel tank and restrict ammo to the remaining guns. The P-40N was a much more thorough job, although yanking the electric starter and reducing the size of the battery went a little far, blaming the Russians for the reduction in fuel capacity for the P-39s seems a bit unfair unless you have actual documentation?

Please remember when judging use on the Russian front that most Russian aircraft had pretty poor armament by western standards. The LAGG-3 and Yaks having for the vast majority, a single 20mm and two 12.7mmm guns at best. Some deleted the 2nd 12.7mm gun due to weight/performance or supply issues? Some flew with a single 20mm, a single 12.7 and a single 7.62. LA-5s had two 20mm guns firing through the prop, lower cycle rate and ammo capacity was ??? Russian 20mm ammo used a light shell, about 75% the weight of the 20mm Hispano shell and with even less HE per shell. I would note that the Yak-9T with 37mm gun is usually credited with a single 12.7mm machine gun as additional armament.

Well, in the long run, this has been a very entertaining and informative thread. I'm not surprised it's still going on. For my perspective, I've said all I want to say, basically the P-39 wasn't too late, just too useless, especially in the ETO.

Past that, Peace out.

Gentlemen, some general comments about the P-39's tricycle landing gear and flying characteristics.

First - if the P-39 is operated within the guidelines of the POH, there will be no adverse ground handling characterizes. I'll go on to say (sticking my neck out) that the P-39 was probably easier to handle on landing, roll out and taxi than any other US tail wheel fighter of the war, again when operated properly.

Although tricycle aircraft, in general handle better on the ground than tail draggers, they can bite you if you do not land on speed and immediately put too much weight on the nose at high speed, in may cases this will cause a NLG shimmy - the B-24 was notorious for this.

As far as the P-39 flying straight and level, all these comments made but no one mentions that in most if not all flight regimes you can trim out any inherent pitch up or down condition, so I take these comments with a grain of salt.

Shortround6 said:

excusing the typo of the production date (N production ended in APril '43)

we are back to repeating ourselves over the P-39s fuel capacity and performance. You don't get both the 120 gal fuel capacity and the the high rate of climb. Pick one.

The argument with the Spitfire is your claim that the P-40N could out climb everything but a Spitfire MK IX and your rather absurd claim that the Spitfire IX wasn't in full production until very late 1942 ( I guess the 4 squadrons at Dieppe in Augs were just using dozens of the prototype MK IXs?).

Against the much older MK V your one test P-39N may be technically ahead, but not by much, if any, at certain altitudes and not enough to make a real difference even at 20-25,000ft.
.

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From my point of view and what "P39" seems to miss about the Spitfire MkV being used in the discussion is that for long periods of 1942 the RAF didn't operate the Mk V over France because it was completely outclassed. A slight improvement on it was not what was needed. The Pas de Calais was where the Germans thought the Allies would land, indeed they did at Dieppe, it would always be contested by Germany with their best fighters for as long as they could. The Mk IX was better in many respects to the FW190 but the main point was it could get away.

FLYBOYJ said:

Gentlemen, some general comments about the P-39's tricycle landing gear and flying characteristics.................. so I take these comments with a grain of salt.

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The P-39 may very well have been easier to handle on the ground, very surprising if it wasn't, and some tail dragger US fighters had a few unique problems of their own, F4Fs for one.

However the transition from approach to actual wheels down may have been a problem?
The P-39 having a higher landing speed than most other (P-38 excepted) US 1942 fighters. While not bad compared to P-47s and late P-51s the P-39 may be 10-20mph faster than P-40s or the navy planes.

Flying any plane on the brink of stall may not be easy and even if a plane is not vicious (rolling on it's back in the blink of eye ) a lack of stall warning can catch the unwary in a difficult position.
Now for many of these planes add 10% or more to approach speed in Pacific Island ( or North African) locations and add 10-20% to the landing run and the potential for landing accidents goes up.
Later planes (like P-47s) almost needed bomber airfields but by then the training was better and the landing fields were getting better on average.

Shortround6 said:

Many evaluations of the P-39 contradict that statement about stalls. and speaking about control reversal. On the P-39 with wing guns and full ammo loads the proper spin recovery use of ailerons was opposite the proper use of ailerons without or with light load of ammo.

You keep claiming one thing and then back tracking. It is true the P-47 couldn't turn with a 109 but the against the 190 it was not so clear cut. And an Aircobra trying to turn against a 109 may not be happy with the result so why pick on the P-47 to begin with?

A Mustang was supposed to be able to get home from the point where it dropped it's tanks and fought for 20 minutes over a distance of 460 miles. The rear tank extended the planning radius to 700 miles. Obviously there were a bunch of missions where the rear tank didn't need to be used or would work perfectly well if some fuel was burned off. A P-51D could do about 5 miles per gallon at 370mph true at 25,000ft. even 25 gallons was good for 125 miles.

You keep getting called on the March 1944 date. That may be the date at which point somebody/s decided the outcome was no longer in doubt, the timing of the outcome was not anywhere near certain and thousands of airmen (on both sides) died in the next year. The air war was hardly over.

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Regarding the March '44 date, most historians say that the Luftwaffe was beaten by that date. Otherwise how did we manage the D-Day invasion the first week of June? I did say the airwar was over by March '44, bad choice of words. The Luftwaffe was beaten by March. To the point that they had to hoard fighters to save them for any big battle they might foresee. They had not been wiped from the face of the earth, but they no longer could put up the most feeble fight without hoarding. They didn't have the fuel to fly them anyway.

I HAVE NEVER BACKTRACKED ON ANYTHING I HAVE POSTED HERE. Yes, acknowledged a few small errors, the airwar was not over in March, I meant to say the Luftwaffe was beaten in March. And the British themselves said the P-400 (one of the heaviest P-39 versions) would easily outturn an Me109E getting on it's tail in three turns.

The P-51 would try to swap ends with a full fuselage tank. Are you going to dispute everything I say? You have so far.

Shortround6 said:

Flying any plane on the brink of stall may not be easy and even if a plane is not vicious (rolling on it's back in the blink of eye ) a lack of stall warning can catch the unwary in a difficult position.
Now for many of these planes add 10% or more to approach speed in Pacific Island ( or North African) locations and add 10-20% to the landing run and the potential for landing accidents goes up.
Later planes (like P-47s) almost needed bomber airfields but by then the training was better and the landing fields were getting better on average.

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And much of this is alleviated with proper training. If you "follow the numbers" there should never be an issue. Also be advised that these vicious tendencies may not happen as quickly as you think.

pbehn said:

www.taphilo.com/history/WWII/Loss-Figures-Aircraft-USA-Training.shtml
The accident rate per 100,000 hrs training/no of fatalities
P38 = 139/379
P39 = 245/395
P40 = 188/350
P47 = 127/455
P51 = 105/137

Looking at the table which is difficult to copy here, the P 39 was not only more likely to have an accident than the other types, if it had an accident it was more likely to be fatal.

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Great chart. In 1942 the P-39 had a lower loss rate than the P-40 (351 vs 507). In 1943 the P-39 had a lower loss rate than the P-40 (228 vs 297). In 1944 the P-39 losses were greater than the P-40 (228 vs 127) but remember that by '44 the P-39 was the main advanced combat trainer and almost every fighter pilot flew a P39 in training. Would think that training accident rate would be higher than normal operating accident rate.

XBe02Drvr said:

Whoa! Bell had to have been playing "Disingenuous" here. The idea that the possibility of aft CG stability issues never entered their minds, considering the unconventional layout of their bird begs credibility. And then to build a wing with no washout, thus guaranteeing a buffetless, violent stall? And whoever thought of not including the entire range of CG scenarios in flight testing?
IIUC, the purpose of the midships engine was to minimize polar moment of inertia and enhance agility. Any kindergartner can forsee that this will likely result in very light stick force gradients and a "twitchy" machine prone to over controlling and PIOs unless compensated for in the flight control linkages. Add that to the wobbly aft CG and the sharp stall characteristics, and you've got a tailor made "lieutenant loser". (The unintended Lomcevak is a free of charge fringe benefit! People pay good money at amusement parks across the land to experience thrills like that.)
It's hard to believe Bell would not have been aware of this, or that they would knowingly foist such a deathtrap on the government.
I've read here and there in dark ages of prehistory that USAAC Wright Pat forced a number of changes on Bell Aircraft to comply with some high ranking infantry officer in Procurement's concept of "improvements". IIRC, this included reducing the wing area to "go faster, like a GeeBee", adding a heavy radio behind the cockpit to talk to ground troops, and removing some bobweights from the elevator linkage and some other (don't remember) weight from the nose section.
Since we seem to have a P-39 expert in our midst, maybe he can enlighten us on this. Fact or fiction? And if fiction, any idea where that story came from?
Cheers,
Wes

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All hearsay. Everything except the actual government/military tests are hearsay. Somebody said this or that and it may have been taken out of context.

I don't know much about washout, but the symmetrical airfoil was in use prior to and throughout the war. If it was a pilot killer it would have been discontinued.

There was more than one purpose for the midships engine. It allowed the very heavy armament of the 37mm cannon, allowed the use of the tricycle undercarriage, and allowed a very streamlined nose contour as well as the enhanced agility. Properly equipped it did not have a rearward CG. Planes can't fly with a rearward CG.

I'm unaware of the Wright Patterson incident. Hap Arnold ordered a complete wind tunnel test of the P-39 by the NACA) shortly after the turbo was discarded which recommended the small reduction of wingspan and lowering the canopy profile along with eliminating the turbo and intercooler and moving the coolant radiator and oil radiators to the wing center section. This was the final configuration that lasted throughout production.

Whether Bell was aware or not, they certainly never "foisted a deathtrap" on the government. The government (military) dictated exactly how any military plane was built and tolerated no deviation from that. The contractors gave the military exactly what they contracted. Any blame lies with the military.

P-39 Expert said:

Regarding the March '44 date, most historians say that the Luftwaffe was beaten by that date. Otherwise how did we manage the D-Day invasion the first week of June? I did say the airwar was over by March '44, bad choice of words. The Luftwaffe was beaten by March. To the point that they had to hoard fighters to save them for any big battle they might foresee. They had not been wiped from the face of the earth, but they no longer could put up the most feeble fight without hoarding. They didn't have the fuel to fly them anyway.
.

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Any historian who says that the Luftwaffe was defeated in March 1944 does not know the meaning of the word defeat.

Operation Steinbock was a German bombing campaign that ran from January to 29 May 1944
Operation Steinbock - Wikipedia

The last German aircraft to crash in the UK was a Ju 88 on the night of 3/4 March 1945, it was one of approximately 100 to infiltrate the RAF bomber stream 24 RAF planes were destroyed 9 damaged with 78 RAF personnel plus 17 civilians killed. The LW lost 22 aircraft with 12 damaged and 48 crew killed. You can say the LW was weakened and in a hopeless position but it wasn't completely defeated until the last days of the war.


Operation Gisela - Wikipedia
aircrashsites.co.uk/air-crash-sites-5/the-last-of-the-luftwaffe/

Actually I read of a case of a P-38 pilot who was not satisfied with merely strafing Japanese airbases but landed and taxied around shooting the place up. He did it a couple of times before the Japanese finally got him on about the third try. Back in the early 70's, I think it was, someone found the remains of a P-38 on a former Japanese airbase. They asked the natives there, who explained the pilot's tactics.

Greg Boeser said:

P-39expert cites Attack and Conquer.
So will I. The 8th FG entered combat 30 April 1942 with P-39Ds and P-400s, within 5 days they had lost 9 pilots and 14 aircraft. Clearly, the pilots were no match for the Tainan AG. The P-39 lacked range to effectively bring battle to the enemy, and were hard pressed to defend their own air base. slow climb performance meant that with the short warning afforded the Port Moresby defenders, they often had no choice but to scramble out to sea to avoid being swatted down while in the climb. Trying to engage the Japanese while still in a climb was suicide as demonstrated by the 75 Sqn. RAAF.
The 8th and 35th FGs held the line in New Guinea during 1942, but suffered considerable losses.
The 80th FS was reequipped with P-38s and entered combat 30 March 1943. The P-38 was a game changer. As the book states, the 35th and 36th Fighter Squadrons continued to fly combat missions in spite of the fact that the P-38 was pushing the fight out of the radius of other fighter types. Both squadrons eventually re-equipped, The 35th got P-40Ns in late 43, and the 36th got some P-39Qs before converting to P-47s in early 44. Both eventually got P-38s

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As I said before the pilots were no match for the Japanese navy pilots. Our kids were green and the Japanese navy pilots were experienced. The P-39 (early heavy D,F,K and L) were all at least 30mph faster than the Zero at all altitudes. They were hard pressed to defend their base yet with all these disadvantages they managed a 1:1 kill ratio.

pbehn said:

This may be true, that the P39 was faster than the P40 but it is an aerodynamic issue not weight, the P51B was faster by about 30MPH than a Spitfire with the same engine and heavier too. How did the P51 and P39 compare with identical engines?

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Best I can tell from the charts the P-51A and the P-39N (same engine in both) had about a 10mph difference at all altitudes. The P-39N being lighter than the P-51A climbed a lot faster..

Shortround6 said:

The P-39 may very well have been easier to handle on the ground, very surprising if it wasn't, and some tail dragger US fighters had a few unique problems of their own, F4Fs for one.

However the transition from approach to actual wheels down may have been a problem?
The P-39 having a higher landing speed than most other (P-38 excepted) US 1942 fighters. While not bad compared to P-47s and late P-51s the P-39 may be 10-20mph faster than P-40s or the navy planes.

Flying any plane on the brink of stall may not be easy and even if a plane is not vicious (rolling on it's back in the blink of eye ) a lack of stall warning can catch the unwary in a difficult position.
Now for many of these planes add 10% or more to approach speed in Pacific Island ( or North African) locations and add 10-20% to the landing run and the potential for landing accidents goes up.
Later planes (like P-47s) almost needed bomber airfields but by then the training was better and the landing fields were getting better on average.

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There was a war goin' on... you have to fly in situations where even the gulls stay on the ground.
To fly a war mission, where actually you have to kill someone, and you know that someone will do his best to try to kill you, is not exactly as to fly a training mission in Southern California or from Decimomannu AB to spend some ammunition in Capo Frasca.
Even Decimomannu AB can be dangerous of course, it is not rare to have 60 kts mistral over there. And a flying accident is a kill the enemy got at no expense.
So to return from a mission in the middle of a tropical storm, landing, at the best, on Marston mats, with an oveheated engine, some holes here and there, fuel to zero, knowing that your plane will not forgive an error at landing, by my personal point of view could only be described as scaring.
Personaly I would have been in this situation inside a Macchi 202 or in a Spitfire or in a Hellcat, but I see that some other gentlemen would prefer to be inside a P-39.
De gustibus non est disputandum, ancient Romans used to say.

pbehn said:

Any historian who says that the Luftwaffe was defeated in March 1944 does not know the meaning of the word defeat.

Operation Steinbock was a German bombing campaign that ran from January to 29 May 1944
Operation Steinbock - Wikipedia

The last German aircraft to crash in the UK was a Ju 88 on the night of 3/4 March 1945, it was one of approximately 100 to infiltrate the RAF bomber stream 24 RAF planes were destroyed 9 damaged with 78 RAF personnel plus 17 civilians killed. The LW lost 22 aircraft with 12 damaged and 48 crew killed. You can say the LW was weakened and in a hopeless position but it wasn't completely defeated until the last days of the war.


Operation Gisela - Wikipedia
aircrashsites.co.uk/air-crash-sites-5/the-last-of-the-luftwaffe/

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Okay, they were weakened to the point of curtailing operations to hoard their remaining planes for last ditch efforts. Definitely in a weakened and hopeless position, especially with Allied airpower reaching its maximum production. Plus no fuel to fly or even train. Call it what you want, they were done.

P-39 Expert said:

Okay, they were weakened to the point of curtailing operations to hoard their remaining planes for last ditch efforts. Definitely in a weakened and hopeless position, especially with Allied airpower reaching its maximum production. Plus no fuel to fly or even train. Call it what you want, they were done.

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Certainly not in March 1944 not by a long way, fuel was a major issue especially after Bagration but in March 1944 they were not defeated and not "done".

P-39 Expert said:

.

I HAVE NEVER BACKTRACKED ON ANYTHING I HAVE POSTED HERE. Yes, acknowledged a few small errors, the airwar was not over in March, I meant to say the Luftwaffe was beaten in March. And the British themselves said the P-400 (one of the heaviest P-39 versions) would easily outturn an Me109E getting on it's tail in three turns.

The P-51 would try to swap ends with a full fuselage tank. Are you going to dispute everything I say? You have so far.

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Last first, yes I am going to dispute the things I think are wrong, of which there is a lot. Like
And the British themselves said the P-400 (one of the heaviest P-39 versions) would easily outturn an Me109E getting on it's tail in three turns.

The P-400 was not one of the heaviest if you compare like to like ( like comparing P-39s with 120 gallon fuel tanks and nearly full fuel)
The 20mm cannon was over 100lbs lighter than the 37mm. The 60 round drum was lighter than the 30 rounds of 37mm ammo.
The basic weight (no fuel, oil, ammo or pilot) for a P-400 was 6328lbs
for a P-39D it was 6290, for a P-39D-2 it was 6421lbs and for a P-39K it was 6392lbs , for a P-39L it was 6467lbs (different prop) and for an early P-39Q it was 6416lbs with the small 87 gallon fuel cells.
Please be careful comparing weights as some accounts/charts, move the pilots weight ( which varied from 160 to 200lbs) and oil from one catagory to another.
Hard to how the P-400 is one of the heaviest if you put the same amount of gas and machine gun ammo in the planes.
But hey, lets not let facts get in the way of a good theory.

As for out turning an 109E, who cares, the 109 went out of production in the winter of 1940/41 and the 109F could easily out turn the 109E using the same engine let alone the improved engines introduced during the summer of 1941. More powerful engine allowed less altitude loss in a given turn.

Others have covered the March 1944 nonsense.

Elmas said:

De gustibus non est disputandum, ancient Romans used to say.

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Not only Romans I knew an Italian bar maid who spoke like that too.