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

[pbehn]

Operational: A fully combat ready aircraft in a fully combat ready unit positioned in an
area capable of putting a hurt on the enemy's aircraft immediately. And, proven themselves
so by putting their aircraft in hostile air.

Thank you Darren, you are right I did ask for help of which P-47D variant was in fully combat
operational service by 25 December 1943. That was the limiting date that pbehn put on his
post. So I used that limitation. Wuzak is partly right about the P-39N's luck against the P-38J-5.
While I believe the Spitfire 14 would do just fine against the Airacobra at tree top levels, I
believe the J-5 lightning would more than have its hands full in a maneuvering contest.

My date of 25 Dec 1943 was itself based on how long a new type aircraft which started to be produced in USA in Dec 1942 would actually be expected to be operational in UK. Shipping and training take much longer than you would think.

 

[Schweik]

We may be getting into arguments about semantics. One man's "twitchy" is another man's "highly responsive" .

yes, I actually think the two things very much go together. I-16's were considered very maneuverable AND "twitchy" - so were Fw 190's for that matter (though I know some people will disagree with that) and even early Ki-43's. Hurricanes were very stable but not as dynamic, by contrast.

Handling and maneuverability are two different things, and maneuverability can mean multiple different things too. An aircraft can be slightly unstable but also very agile simultaneously. That is actually what I was alluding to - for a pilot experienced with this particular kind of challenge it isn't really a problem at all. Clearly the Soviets had few problems with this aspect of the P-39, comparatively, but it's also very clear that many if not most American, Italian, and French pilots positively dreaded maneuvering with the P-39 and feared that it would go into a spin that would kill them. A lot of them found the P-39 risky to bail out of too due to the 'car type' doors (though some people in New Guinea seemed to have made a career out of bailing out of them).

I think being comfortable with "twitchy" aircraft, and spending more time in familiarization with the type- is one of the main reasons the Soviets did so much better with the P-39, aside from the requirements / conditions of the Theater.

S

 

[Elmas]

The most dreaded thing Italian P-39 pilots feared were the nickname the other pilots, who remained in the Stormo equipped with Macchi gave them: "the truck drivers", for the car style door of their planes...

 

[Elmas]

RTO - Eastern Front, I assume.
...

Yes, Russian Teater of Operation.

 

[Dimlee]

That Lend Lease aircraft site is a fantastic resource, and that article in particular is indeed a good read and it helped me understand how the Soviets did so well with the P-39. The Soviets got their P-39's in December and January of 1941/42, and spent the next 4 moths preparing them, training pilots and doing their workup. Some quotes from the article mentioned:



This is one of the key aspects of solving the mystery of why the Soviets got so much mileage out of this aircraft when nobody else could. They liked it initially and recognized it's potential, they had already had experience with Anglo-American fighters and had recognized certain problems they wanted to avoid with the P-39. So they collected all the ones they were sent in some airfield in Siberia, had test pilots fly them, did a complete workup on systematic adjustments, some already widely known like removing the wing-guns to save weight, but others were less widely understood like winterizing and working out maintenance systems in advance. For example they had to modify all Anglo-American fighters so that all fluids could be drained out every night (not just during overhauls) during the Winter, which meant adding plugs and drains on some systems not designed for it - and do it in such a way that would not damage hydraulics, coolant or oil. They did this much more carefully with the P-39's thanks to the work-up, by comparison with the P-40's and Hurricanes this was done in the field, haphazardly, often with damaging results. Another major issue was the "oil culture" and fuel requirements. Finally they trained their pilots to use the new aircraft and worked out tactics (exploiting the radios, among other things) for their optimal use.

One of the big differences between the P-39's and the P-40's and Hurricanes they had gotten earlier was that the P-39's came with spare engines and at least some spare parts. The other parts and supplies were figured out by Soviet engineers, copied as needed added to the Soviet logistics systems. Thus when P-39 engines burned out, as they quickly did in field conditions partly due to using them at high power settings, they could be replaced with new engines. This was much more of a problem with P-40's for example which initially came without any spare engines.

Once all of this was all worked out, and only then, the Soviets committed the P-39 in some numbers, and it caused something of a shock to the Germans.

Why they liked it so much

• It was the most similar to Soviet fighters. The P-39 was the only Anglo-American single-engined fighter with a cannon in the spinner plus nose guns. Their aerial gunnery training was mostly oriented toward nose guns and most (except I-16 pilots or those checked out on P-40's or Hurricanes) were not used to wing-guns. The P-39 was streamlined like a Soviet fighter. It was agile and climbed well. These characteristics endeared it to the Russians and marked it for the careful work-up it got.
• It was fast. Properly stripped down, the P-39 was faster than a Bf 109E at low altitude and arguably, maybe even Bf 109F. No Soviet planes could match this down low (the MiG 3 could at high altitude only but that really didn't matter in combat along the Russian Front).
  
• They got some new ones. Most of the P-40's and Hurricanes they had gotten to that point were already worn out battle veterans with weakened engines. But the British didn't use their P-39's very much at all before sending them on, and the Americans sent new ones.
  
• It had good radios. The Soviets had been unable to get enough radios into production and the ones they had suffered from very short range and ineffective transmitters, due to ineffective grounding and other problems. All the Anglo-American planes, the American in particular, had good reliable radios for both transmitting and receiving. This was a huge help for the Soviets!
  
• It was all -metal. Soviet planes were mostly made with substantial wooden parts, using new types of plywood which had not in all cases been fully developed and sometimes failed in flight. The P-39 had none of these problems.
  
• Superior build quality. All of the newer Soviet fighters - MiG-3 / La GG-3 / Yak 1 / Yak 7 etc., suffered from severe problems with build quality. Many parts which would be interchangeable on a Western fighter were unique one-off's on Soviet planes. Variations in production quality, which in many cases was being done in factories that had just been moved across the Urals and didn't even have roofs, could mean that an aircraft with an official speed of 350 mph was in reality limited to 280 or 290 mph. The early P-39 didn't have the world's best build quality (some serious defects were revealed by British testing such as landing gear doors opening up at speed etc.) but it was better than all of the newer era Soviet planes up until probably 1943.
• The altitude ceiling didn't matter - almost all of the bombing in the Russian Front zone was tactical and there was often a cloud ceiling at ~4-5,000 feet especially during the long winter. So not only did most of the fighting take place at low altitude the Germans couldn't use their superior climb and ceiling to attack from above all the time like they did so much in North Africa.
  
• They liked the heavy armament and heavy construction. The Soviet pilots actually liked the Oldsmobile 37mm as it allowed them 'authority' in a head-on pass with German fighters (who would veer off to avoid what they described as an "anti-aircraft caliber weapon") and the Soviets seemed to be able to get it working, although in some cases it was replaced by 20mm guns. They also felt the P-39 could survive belly landings which would destroy most other aircraft.
• Dive speed and high-G turns. One effect of the heavy construction was that the P-39 could out-dive most other Soviet planes, which had fairly low speed limits due to their partly wooden construction and typically uneven-build quality. The P-39 could dive very fast and could evade Bf 109's this way. This was key to the survival of Soviet P-39 pilots, the ability to disengage. This also meant that the P-39 could pull higher-G turns (so long as the pilot could keep it out of a Spin) than some other Soviet types.

Most of this of course is well known. So we can see why the Soviets liked the P-39. The question remaining is why they did so well with it compared to say, the British, the Americans, the Free French, the Italian Co-beligerant forces who suffered from it so badly, and whoever else got stuck with it (I think Australians maybe?). This is the biggest question to me.

Why the Soviets did so well with it compared to others

• The main reason is I think the big workup described in that article.on Leand Lease P-39's. In general with early war Anglo-American aircraft, success seemed to hinge on modifying the aircraft appropriately for actual use (as opposed to however they arrived from the factory) usually involving both weight saving and maintenance issues, and training on the particular fighter type. Flying a P-39 in combat right out of flight school was a recipe for death. The Soviets solved both of these problems with their extended workup of the P-39.
  
• The lower altitude ceiling - the tactical flight ceiling of the Russian Front battlefield really made a difference. It was a low-altitude battlefield, and due to the frequent cloud ceiling, German fighters often could not attack from above. Almost all of the bombing on both sides was dive bombing or close-support (Sturmovik) low altitude attacks. This was one of the main weaknesses of the P-39 for other Theaters but it just didn't matter nearly as much on the Russian Front.
  
• Range didn't matter as much on the Russian Front- I think range is the main reason the P-39s did so poorly in general in the Pacific. Altitude ceiling of course was more important there too, since the Japanese were using level-bombers that were coming in at 20-25,000 feet. But short range exacerbated that problem because short range meant less time to get up to altitude. But the Russians were already operating from forward airfields close to the front and combat was at low altitude, so range wasn't as important.
• The Russians were used to twitchy planes. I think this is one of the other main factors. Western allied pilots were afraid of the P-39, they didn't trust it, because it was somewhat unstable aircraft which could go into an unforgiving spin (the 'flat spin' and tumble are debated issues, but lets agree a spin in a P-39 could be dangerous). The Soviets had a head start on this due to the 4 month training and evaluation period they did, but they also had a lot of pilots already used to 'twitch' fighters and able to fly well in them and get kills in spite of their touchy handling. The I-16, the LaGG-3, the MiG 3, and the early Yak 1 were all known to be 'twitchy' fighters. Many Soviet pilots assigned to P-39 fighters came directly from flying these somewhat 'difficult" planes. This I suspect is one of the other crucial missing ingredients.
• The Soviets had some input into the aircraft development. Later model P-39's were adjusted according to feedback from their only happy customer, the Soviets, and the P-63 was basically built to Soviet specifications and under direct Soviet supervision.

I think ceiling and range were the two biggest performance issues preventing the P-39 from doing well in the Pacific. i suspect the 'twitchyness' and training were the major issues in the Med.

Anyway, that's my $.02

S

And very valuable $.02, indeed !
Many thanks to Schweik for such detailed commentary. And - especially - for bringing attention to:
1. Massive pre-flight preparations, research and improvements. They continued with later models as well.
2. Advanced training that many pilots received. Human factor should not be underestimated.

Just a couple of small things:
- 22 ZAP and other reserve/training regiments were never based in Siberia. Siberian airfields were just transit points for AlSib route.
- Certainly "not the most similar to Soviet fighters". Actually most, if not all qualities of P-39 praised by VVS pilots were not typical to domestic production. As for nose guns orientation - interesting hypothesis, but it needs to be verified.

 

[Dimlee]

Also, not many kills against JU-87s. I thought they were pretty numerous on the Eastern Front. Were they depleted by this time, or was it due to their agility and their tail gunner?
Cheers,
Wes

Good question. I'd suggest both general attrition and (probably) Ju 87 tactics changes after 1941. If they were more and more used at lower altitudes then their typical opposition would be Yak and La, IMHO. P-39 did not excel very low.
One of Rudel's stories was about P-39 on his tail in long ground level chase in 1944...
As for numbers of Ju 87, if someone has enough time to count them from here or from similar source:
http://www.oocities.org/sturmvogel_66/LWJul42.html#May43

 

[Schweik]

And very valuable $.02, indeed !
Many thanks to Schweik for such detailed commentary. And - especially - for bringing attention to:
1. Massive pre-flight preparations, research and improvements. They continued with later models as well.
2. Advanced training that many pilots received. Human factor should not be underestimated.

Just a couple of small things:
- 22 ZAP and other reserve/training regiments were never based in Siberia. Siberian airfields were just transit points for AlSib route.
- Certainly "not the most similar to Soviet fighters". Actually most, if not all qualities of P-39 praised by VVS pilots were not typical to domestic production. As for nose guns orientation - interesting hypothesis, but it needs to be verified.

Interesting, do you know where the 22 ZAP base was exactly? I thought it was Western Siberia / Central Asia.

Similarity I think is mainly regarding the nose gun and overall streamlined appearance, but also small wings and some other features. Admittedly just a theory. I think the nose gun thing is important because so many Soviet pilots mentioned it.

S

 

[Schweik]

The most dreaded thing Italian P-39 pilots feared were the nickname the other pilots, who remained in the Stormo equipped with Macchi gave them: "the truck drivers", for the car style door of their planes...

For Italians, pride is very important of course . A lot of them died in accidents in P-39's though including IIRC at least one important ace, so that is pretty tragic.

S

 

[Elmas]

Still, I cannot understand how a plane like P-39 could have had such a good score against Luftwaffe fighters. Difficult handling, not the best suitable armament...

Certainly, while in the Western Front Luftwaffe gave precedence to quality, in the Eastern Front took precedence quantity and, probably, the percentage of unskilled LW pilots there was in the East was higher.

Or was outstandingly high the skill of Russian pilots? Could be, but I doubt: Ulrich Rudel could ride on a Stuka well into 1944, if not 1945 on the Russian Front...

 

[Schweik]

Good question. I'd suggest both general attrition and (probably) Ju 87 tactics changes after 1941. If they were more and more used at lower altitudes then their typical opposition would be Yak and La, IMHO. P-39 did not excel very low.
One of Rudel's stories was about P-39 on his tail in long ground level chase in 1944...
As for numbers of Ju 87, if someone has enough time to count them from here or from similar source:
http://www.oocities.org/sturmvogel_66/LWJul42.html#May43

From reading Black Cross / Red Star it seems like a lot of German bomber sorties were able to take place without fighter opposition, especially during periods when the LW had achieved local air superiority such as during the first part of Stalingrad.

S

 

[Elmas]

For Italians, pride is very important of course . A lot of them died in accidents in P-39's though including IIRC at least one important ace, so that is pretty tragic.

S

Last victory of Teresio Martinoli, top italian Ace in the Regia Aeronautica, was against a P-39 in Tunisia, and then he died in a training flight with an Airacobra. His last victory, a Ju-52 over Jugoslavia, was with a P-39 as well.
Googling "Martinoli, Tunisia" I did find this:

"In the final chapter in "Fighters over Tunisia" (by Shores, Ring & Hess), "Conclusions", there are some quite interesting pilot comments on the various fighter planes used. With earlier discussions on the Airacobra in mind, it is interesting to note that there are several pilot remarks on the Airacobra, and none of them is kind. In fact, no fighter type is torn apart to such an extent by the pilots interviewed in "Fighters over Tunisia" as the Airacobra.

Jerry Collingsworth, who flew as a Lieutenant with US 31st FG in Tunisia, is quoted saying:

"The P-39 [Airacobra] was a miserable fighter for Tunisia; we used to have to escort them because the Me 109 and Fw 190 outperformed them in every conceivable way; dive, climb, manoeuvre, speed - you name it!" (p. 416)

Wg.Cdr. M. G. F. Pedley, who served as a Wing Leader in 323 Wing in Tunisia, is quoted on the same subject:

"P-39 Airacobra . . . Its rate of climb was poor, armament inefficient and engine unreliable." (p. 424)

John L. Bradley of US 33rd FG is quoted to say this on the Airacobra:

"I flew a couple of escorts for P-39s during my tour. Many of the pilots on these aircraft were afraid of them and figured they didn't have a chance if they were jumped by enemy aircraft without top cover." (p. 404)

There is not one positive word on the Airacobra among these harsh condemnations. Hardly suprising, since by looking up the two Airacobra units operating in Tunisia (81 FG and 350 FG) in the index of "Fighters over Tunisia", one gets the impression of a fighter plane which was badly mauled by Luftwaffe fighters without any chance to pay back. In late February 1943 350 FG was withdrawn from first-line service and degraded to coastal patrols with the North-West African Air Force. A little later, the other Airacobra unit, 81 FG, was badly beaten up by II./JG 77.

On 13 March 1943, Bf 109s of II./JG 77 - possibly reinforced by some Bf 109s from III./JG 77 - attacked 12 Airacobras of 81 FG, provided with top cover by Spitfires of 307 and 308 Sqns. In the ensuing combat, seven of the twelve Airacobras were shot down without any loss to the Germans. The shot down Airacobras were piloted by Lt. Murray, Lt. Turkington, Lt. Smith, Lt. Leech, Lt. McCreight, Lt. Lewis, and Lt. Lyons. The Eastern Front veteran Ernst- Wilhelm Reinert scored five victories against Airacobras (at 1744, 1748, 1756, 1756 again, and 1800 hours)

(Earlier that day, II./JG 77 had clashed with 34 P-40 Warhawks of US 57 FG and shot down four of these against one own loss. II./JG 77 claimed to have shot down five Warhawks, including two by Ernst-Wilhelm Reinert; thus, the Eastern Front veteran Reinert scored seven victories against US fighters on 13 March 1943, increasing his total victory tally to 135.)

All of this, including Reinert's feat, is a perfect illustration of the Luftwaffe Eastern Front veterans repeating what they previously had accomplished on the Eastern Front against the same kind of fighters.

To compare with the Eastern Front, 216 SAD, equipped with Airacobras and Warhawks, sustained five Airacobras and a Warhawk shot down in a similar outburst of air fighting on 15 April 1943.

However, to be fair, it should be noted that only a few days before II./JG 77's massacre on US-piloted Airacobras, other Airacobras flown by Soviet pilots of 19 GIAP managed to shoot down three of III./JG 5's Bf 109s in a single engagement (against only one own Airacobra lost). Lt. Jakob Norz's Bf 109 F-4 (WNr 13108), Lt. Gerd Grosse-Brauckmann's WNr 10183, and Fw. Ernst Schulze's WNr 10122 were all reported destroyed as a result of that combat. Without drawing any far-fetched conclusions, I can only note that AFAIK the American Airacobra pilots never managed to accomplish anything similar against Luftwaffe fighters.

In any case, shortly after it had received such a bad beating by II./JG 77, this US Airacobra unit also was withdrawn from first-line service and joined the other Airacobra unit in coastal patrols with the North-West African Air Force - where they were saved from encountering any Bf 109s or Fw 190s."

and also

In late February 1943, the Airacobra-equipped 350th FG was withdrawn from first-line service and degraded to coastal patrols with the North-West African Air Force. It is not quite correct to state that "it returned to front line action", as you will see below.

In fact, the 350th FG Airacobras never were sent back to regular first-line service. From February 1943, their dominant task would remain coastal patrols in the rear area. In November 1943 it was transferred from North Africa to Cagliari/ Elmas, Sardinia."

I'm looking if I will be able to find some pics of Airacobra here in Sardinia...

P-39 is certainly a very controversial aircraft.

 

[DarrenW]

Operational: A fully combat ready aircraft in a fully combat ready unit positioned in an
area capable of putting a hurt on the enemy immediately. And, proven themselves
so by putting their aircraft in hostile air.

Thank you Darren, you are right I did ask for help of which P-47D variant was in fully combat
operational service by 25 December 1943. That was the limiting date that pbehn put on his
post. So I used that limitation. Wuzak is partly right about the P-39N's luck against the P-38J-5.
While I believe the Spitfire 14 would do just fine against the Airacobra at tree top levels, I
believe the J-5 lightning would more than have its hands full in a maneuvering contest.

Thanks Corsning, I just needed the clarification. And just to make clear I enjoy your posts and value your input as always.

 

[DarrenW]

So are we in agreement that the loaded weight of the Q model was roughly 150-200lbs more than the P-39N (extra weight of guns, ammo, and additional fairings) ? How would an increase like that affect the level speed and climb rate?

 

[Schweik]

Earlier that day, II./JG 77 had clashed with 34 P-40 Warhawks of US 57 FG and shot down four of these against one own loss. II./JG 77 claimed to have shot down five Warhawks, including two by Ernst-Wilhelm Reinert; thus, the Eastern Front veteran Reinert scored seven victories against US fighters on 13 March 1943, increasing his total victory tally to 135.)

All of this, including Reinert's feat, is a perfect illustration of the Luftwaffe Eastern Front veterans repeating what they previously had accomplished on the Eastern Front against the same kind of fighters.

Good post overall, and yes these were the same quotes included in MAW III which I was referring to about US pilots being "afraid" of their P-39's.

Be careful lumping the P-40 and the P-39, especially the late model P-40's flying with the 57 FG, because based on the newer books by the same author (Shores) which compare actual victories vs. losses on each side, USAAF P-40 squadrons on numerous occasions shot down more Bf 109's than they themselves lost. I cited about ten examples in another thread - I know this too is a controversial topic and I don't want to detail this conversation about the P-39 so if you want to discuss P-40's post in that one probably or create a new thread.

But here are a few examples involving USAAF P-40 F/L vs. Bf 109s specifically:

23 March 1943 (USAAF 79 FG P-40F vs. JG 77 & JG 51) 2 Bf 109s lost to P-40's / 0 P40's lost
29 March 1943 (USAAF 33 FG P-40L vs. JG 77) 6 Bf 109 lost (4 destroyed +2 crash-landed) and 3 He 111's and 1 Ju 88 / 2 P-40's lost (1 to AA)
31 March 1943 (USAAF 33 FG P-40L vs. JG 77) 6 Bf 109 lost (3 destroyed +3 crash-landed) / 1 P-40 lost

However, to be fair, it should be noted that only a few days before II./JG 77's massacre on US-piloted Airacobras, other Airacobras flown by Soviet pilots of 19 GIAP managed to shoot down three of III./JG 5's Bf 109s in a single engagement (against only one own Airacobra lost). Lt. Jakob Norz's Bf 109 F-4 (WNr 13108), Lt. Gerd Grosse-Brauckmann's WNr 10183, and Fw. Ernst Schulze's WNr 10122 were all reported destroyed as a result of that combat. Without drawing any far-fetched conclusions, I can only note that AFAIK the American Airacobra pilots never managed to accomplish anything similar against Luftwaffe fighters.

Good point and absolutely true. I believe the reasons are as outlined in my previous post. It's certainly a striking contrast.

In any case, shortly after it had received such a bad beating by II./JG 77, this US Airacobra unit also was withdrawn from first-line service and joined the other Airacobra unit in coastal patrols with the North-West African Air Force - where they were saved from encountering any Bf 109s or Fw 190s."

Quite true but even as the P-39 was relegated to coastal patrol duties, it's worth noting that multiple RAF, Free French and USAAF squadrons were still using the P-40 for front line combat operations, including escort and fighter sweep missions, well into the middle of 1943, with some units continuing until 1944. In Shores MAW P-40 squadrons are still scoring kills against the Luftwaffe well into 1943 as I noted above. it's also worth pointing out that while there was only 1 US ace flying the P-39, and no others in the West that I know of (at least, none who made 5 kills in a P-39) there were at least 80 P-40 aces in the Med Theater alone and something like 15 or 20 double aces. The Soviets also had dozens of P-40 Aces and several double, triple and even quadrouple aces flying the type, including 3 HSU recipients.

S

 

[pbehn]

Since most P-39s sent to Russia were the N and Q versions, is it possible these were quite well sorted as far as engine and CoG issues went while the earlier versions just shouldn't have been put into service?

 

[Shortround6]

So are we in agreement that the loaded weight of the Q model was roughly 150-200lbs more than the P-39N (extra weight of guns, ammo, and additional fairings) ? How would an increase like that affect the level speed and climb rate?

The weight alone has a negligible impact on speed. It is the drag associated with the weight that causes the speed reduction.
For instance if you were add internal ballast with NO exterior changes the only increase in drag would be a very marginal shift in the angle of attack of the wing and the induced drag, since forces on the plane (both drag and lift) go up with the square of the speed adding a few hundred pounds to an aircraft does very little to the speed.
However, pods, protruding gun barrels, gun ports/troughs, cartridge ejection slots can cause a much bigger disruption of airflow and increased drag.

When climbing there is a bit of a double whammy. Since climb speed is relatively low, in fact it is a cross/blend between lowest speed with good controllability and the lowest drag speed ( lowest drag caused by lift and lowest drag caused by speed/shape). I am not explaining that well.

Picture worth 1000 words. Climb is done near the minimum drag speed, an increase in weight is going to cause the lift induced drag to rise at low speed in greater proportion than at high speed. This leaves less power to perform the climb with and when climbing you are lifting every pound.

Hope that makes sense?

 

[Shortround6]

Since most P-39s sent to Russia were the N and Q versions, is it possible these were quite well sorted as far as engine and CoG issues went while the earlier versions just shouldn't have been put into service?

I am not sure how bad things really were and how much was "hanger talk". The P-39 certainly had a higher landing speed than a P-40 but then so did a P-47. The P-39 may have been more responsive than some other fighters, more results (change of angle of aircraft)for the same movement or effort on the stick/rudder pedals.
The P-39 may parallel the B-26? Early pilots transitioning from easier to fly aircraft had trouble with it (and inexperienced instructors didn't help) while later pilots had a better training program?
Once a plane gets a bad reputation it takes a LOOOOOOONG time to live it down.

IN combat in 1942 and early 43 the P-39 was usually going to be the plane being dived down upon and seldom being the plane doing the diving upon others, which means it is at a disadvantage a larger percentage of the time.

I am not saying the P-39 was a great combat plane in the west, just that some pilot's comments have to be put in context.

 

[pbehn]

The weight alone has a negligible impact on speed. It is the drag associated with the weight that causes the speed reduction.
For instance if you were add internal ballast with NO exterior changes the only increase in drag would be a very marginal shift in the angle of attack of the wing and the induced drag, since forces on the plane (both drag and lift) go up with the square of the speed adding a few hundred pounds to an aircraft does very little to the speed.
However, pods, protruding gun barrels, gun ports/troughs, cartridge ejection slots can cause a much bigger disruption of airflow and increased drag.

When climbing there is a bit of a double whammy. Since climb speed is relatively low, in fact it is a cross/blend between lowest speed with good controllability and the lowest drag speed ( lowest drag caused by lift and lowest drag caused by speed/shape). I am not explaining that well.
View attachment 488300
Picture worth 1000 words. Climb is done near the minimum drag speed, an increase in weight is going to cause the lift induced drag to rise at low speed in greater proportion than at high speed. This leaves less power to perform the climb with and when climbing you are lifting every pound.

Hope that makes sense?

Great post, the proof of that particular pudding is the Mustang Mk I (P51A) bigger and heavier than the P39 but faster, it actually did do 400MPH with and Allison engine, and the P51B bigger and heavier than the Spitfire but faster at all altitudes on the same engine. Rates of climb may have been slightly lower but not seriously behind.

 

[pbehn]

I am not sure how bad things really were and how much was "hanger talk". The P-39 certainly had a higher landing speed than a P-40 but then so did a P-47. The P-39 may have been more responsive than some other fighters, more results (change of angle of aircraft)for the same movement or effort on the stick/rudder pedals.
The P-39 may parallel the B-26? Early pilots transitioning from easier to fly aircraft had trouble with it (and inexperienced instructors didn't help) while later pilots had a better training program?
Once a plane gets a bad reputation it takes a LOOOOOOONG time to live it down.

IN combat in 1942 and early 43 the P-39 was usually going to be the plane being dived down upon and seldom being the plane doing the diving upon others, which means it is at a disadvantage a larger percentage of the time.

I am not saying the P-39 was a great combat plane in the west, just that some pilot's comments have to be put in context.

The pilots of 601 sqdrn RAF had previously flown Hurricanes, the take off of the P-39 was much longer, so much that it couldn't be used on some RAF bases. The landing speed and I presume take off speed was much higher, the pilots manual says that you can side slip to lose height but the rate of descent means this shouldn't ne necessary. However of the planes used by 601, one crashed after take off with engine failure killing the pilot, another crashed during aerobatics killing the pilot while another had to do a wheels up landing. The actual tests by Boscombe down said it could be used as a low altitude fighter, it just happened that the pilots actually using it hated it. Personally I think Operation Barbarossa and Japanese activities in the Pacific trumped all discussions. The British were already sending planes and tanks to Russia starting June 1941, sending P39s to UK while UK was sending Hurricanes and later Spitfires to Russia makes no sense at all.

 

[Vincenzo]

But here are a few examples involving USAAF P-40 F/L vs. Bf 109s specifically:

23 March 1943 (USAAF 79 FG P-40F vs. JG 77 & JG 51) 2 Bf 109s lost to P-40's / 0 P40's lost
29 March 1943 (USAAF 33 FG P-40L vs. JG 77) 6 Bf 109 lost (4 destroyed +2 crash-landed) and 3 He 111's and 1 Ju 88 / 2 P-40's lost (1 to AA)
31 March 1943 (USAAF 33 FG P-40L vs. JG 77) 6 Bf 109 lost (3 destroyed +3 crash-landed) / 1 P-40 lost

S

Nikademus time ago posted him sum from Shore's books on war in Africa this give 522 P-40 losses vs 206 109 losses (my sum for both the books)