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

Vincenzo said:

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)

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Interesting, do you have a link to the thread where he posted that? I'd like to look at how he added that up - but it is not too far from what I would have expected from reading both books myself. I'm guessing about three-quarters of those losses are all early model P-40s - Tomahawk and Kittyhawk Mark 1, probably at least half of them from the South African squadrons, vs. 109F and G. You can also add ~ 100 shot down MC 202s (guessing the total) to that number as they were fighting the DAF in the same air battles.

But if you ran the numbers from say the middle of 1942 through where MAW III ends (about April of 1943) I think it's basically even.

When I have the time I plan to put all of Shores numbers into a database so I can do a little bit of a deeper dive & break down for example late model p-40s versus the 109's, and specifically USAAF P-40's vs 109F and G - I have been starting that process and I would say at this point it looks like USAAF P-40 units came out ahead of their Luftwaffe adversaries overall.

It gets harder to sort out though because most days there's multiple aircraft types in action including Spitfires and P38, Fw 190 and MC 205 and so on. The specific days that I posted upthread were all days in which either P-40 squadrons were fighting by themselves, or it was clear from the German records that their planes were shot down by P-40's specifically (quite often the Germans specified what aircraft type they took losses too, and usually at least gave the area where their planes went down, making it possible to cross-check against allied claims).

However, you won't find any days where American piloted P-39's shot down 6 Bf 109's for no losses, and I daresay you won't find many of the same with RAF Hurricanes and not too many with Spit V's. My point was that the P-40s were not the pushover we had once been led to believe in the Med, and specifically late model P-40s were fairly evenly matched to the Bf 109 in particular.

P-39s clearly were not in the Med. P-38s didn't do that well either.

Volume IV of MAW should tell us more.

S

Elmas said:

...In late February 1943, the Airacobra-equipped 350th FG was withdrawn from first-line service and degraded to coastal patrols with the North-West African Air Force.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.

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I agree with your last sentence but in fact 350th returned to first-line service, on 9 Feb. 1944 it moved to Corsica (much nearer to Italian mainland and more importantly north of the frontline there. In fact in early April 1944 the fighter-bomber P-39s made important contributions to the interdiction of German lines of communications, 0n 2 Apr they badly damaged a bridge over the River Ombrone,S of Grosseto and on 11th destroyed the tracks N of Montalto di Castro. They also combat with 109s and 190s during these missions. see e.g.:2-6 April 1944

Juha

Shortround6 said:

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?

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It makes perfect sense.

Shortround6 said:

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.

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It's all about L/D, lift over drag. When you're at the speed which gives you the most lift at the least cost in drag, your excess power and your Rate of Climb are maximum. That's the sweet spot in your pretty little graph. The same principle under slightly different circumstances will give you your best glide.
Cheers,
Wes

That is true but on some aircraft the "sweet" spot was a little too close to a speed that gave stability problems at the angle of attack needed for max climb. So max climb speed was sometimes a bit faster (by 20mph or so) over the sweet spot to insure good control response in the climb.
Again, forces acting on the vertical stabilizer or horizontal stabilizer go up with the square of the speed. going from 160mph to 180mph increases these forces by around 26%

Shortround6 said:

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.

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Why is it so hard to reconcile the differences between P-39 success in USSR and elsewhere? Let me count the ways. SR6 and others bring up a good point in pilot attitude and training. Pilots in MTO and NA were stuck with what was generally considered an also-ran, likely trained by pilots who detested and feared it, and watched in envy as their colleagues got to fly "the good stuff". This doesn't do good things for morale or esprit de corps, and such conditions don't make for confident, aggressive fighter pilots. Chances are their outfits also weren't high in the pecking order for the resources to keep their aircraft up to date. Add to that a hot humid climate with high density altitudes and an overweight plane with a weak supercharger and a reputation for nasty accelerated stalls and it's understandable why its combat performance might be less than stellar against planes optimized for higher altitudes and thinner air.
Now let's go to the Eastern Front. Here we have Airacobras that have been scientifically analyzed and adapted to the conditions flown by pilots who's prior experience has been in relatively primitive, somewhat shoddily constructed domestic aircraft. It must have seemed like a snazzy imported sports car to them. And its real world battlefield performance was a cut above those tired old dogs in the Med because of the carefully analyzed adaptations it received. The cold dense air optimized it's performance and negated any advantages its more elegant opponents might have had, allowing it to give as good as it got, or even better. In all the performance discussion on this thread there's been very little acknowledgement of the huge difference air density makes in comparative performance other than raw altitude.
Cheers,
Wes

A long time ago I had a conversation over a couple of bears with a pilot that had flown the P-39. P-40 and P-51 in combat against the Japanese. He considered the p-39 to be a huge improvement over the P-36 he was fling before the war. He also said the P-40, overall, was equal to the P-39 in combat and not an improvement. The problem with the P-39 was the tropics and the electrical system which never seemed to be 100 percent functional. No one was worried about accelerated stalls or felt the plane was unstable. On the P-51 he said if they had had them sooner "We all would have been F****** heroes"

Well this is very interesting....

http://www.wwiiaircraftperformance.org/P-39/P-39M-3_42-4706_FS-M-19-1511-A.pdf




The two externally mounted caliber .50 wing guns, their fairing, brackets, and equivalent weight of ammunition were removed. Additional ballast was installed to compensate for this removal....




Difference in speed was 12.5 mph for this particular aircraft, with and without gun pods. But at least we can see that the speed of the P-39Q WITHOUT the wing guns was 13.5 mph SLOWER at the critical altitude of our one and only P-39N test aircraft . But to be fair the P-39Q was ballasted for the additional weight of the guns and ammo, and it weighed almost 600 pounds more than the P-39N at take-off. What do you gentlemen make of this?

Schweik said:

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

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22nd ZAP was based mainly in Ivanovo (about 250km NE of Moscow). Also in Kineshma for short period in 1942.
P-39 training was done later in other locations as well, for example, in Azerbaijan.

XBe02Drvr said:

It must have seemed like a snazzy imported sports car to them.
Wes

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Agree.
Higher quality equipment boosted morale, indeed. That was said by Soviet veterans and not only pilots. It cured despair caused by catastrophic losses of early war. It helped soldiers to feel themselves not as a cannon meat hastily prepared for another slaughter but as warriors again. It restored self respect. "Human factor" - which is hard to figure out of charts and tables...

Dimlee said:

As for nose guns orientation - interesting hypothesis, but it needs to be verified.

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What's to verify? It's a known and obvious fact. Getting the highest percentage of bulletstrikes into a target profile is going to occur if your guns are clustered together and shooting down the sightline to the target, even if there are variances in the trajectories. Witness the P-38 or the A-20/B-25/A-26 strafers. Convergence angle is minimal and is only in one plane, resulting in a much longer "sweet spot" rangewise where the bullet density is maximum. All it takes is one 37MM hit. Game over.
Not like "sawing away" at your target with multiple wing mounted .30s.
Cheers,
Wes

DarrenW said:

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?

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Assuming no increase in parasitic drag, a 1% increase in weight will cause about a 1.5% increase in power required for flight at the best rate of climb speed (drag coefficient will remain the same but speed will increase 0.5% and power required is proportional to speed cubed). If the plane had a 1,000 shp engine, and needed 500 shp for level flight before, it would have 500 shp to use for climb. Add 1% to its weight, it now needs 508 shp for level flight, and has only 492 shp for climb, a drop of 1.5%.

XBe02Drvr said:

What's to verify? It's a known and obvious fact. Getting the highest percentage of bulletstrikes into a target profile is going to occur if your guns are clustered together and shooting down the sightline to the target, even if there are variances in the trajectories. Witness the P-38 or the A-20/B-25/A-26 strafers. Convergence angle is minimal and is only in one plane, resulting in a much longer "sweet spot" rangewise where the bullet density is maximum. All it takes is one 37MM hit. Game over.
Not like "sawing away" at your target with multiple wing mounted .30s.
Cheers,
Wes

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Sorry, we are talking about different things.
I'd like to verify this hypothesis (quoting original message of Schweik):
"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"
Schweik's argument is valid, I'm just not sure if it's true. It does require verification since not every "pre P-39" fighter type in VVS had only nose MG.
But this argument reminded me about another and real feature of VVS pre-war training: deficit of gunnery practice. If we assume that pilots who received P-39 were poorly trained in gunnery, then (probably) central mounted guns were easier for them ? For the obvious reason you stated in your post.

Dimlee said:

But this argument reminded me about another and real feature of VVS pre-war training: deficit of gunnery practice.

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Didn't VVS pre-war training feature a deficit of all kinds of practice, not just gunnery? Didn't the Japanese in Manchuria in 1938 point out some pilot proficiency deficits in the VVS?
Cheers,
Wes

Elmas said:

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...

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Edited in bold by me.
We probably should define "skill". Soviet pilots could be good in aerobatics but bad in tactics, better or worse in communication, gunnery, individual initiative, etc.. Then there were management skills at squadron and higher levels. And ability of skilled commanders to withstand pressure from less smart superiors (huge issue in Red Army overall). "Average quality" of VVS is hard to define, this is very complex subject and politically sensitive - yes, until today. My humble opinion (some of my fellow Russians will curse me): average qualification of individual in VVS remained below the counterpart in other major air forces, through all WWII (and probably for most period of Cold War as well). But from summer 1943 and on there was enough "higher than average" personnel to gain superiority, step by step.

XBe02Drvr said:

Didn't VVS pre-war training feature a deficit of all kinds of practice, not just gunnery? Didn't the Japanese in Manchuria in 1938 point out some pilot proficiency deficits in the VVS?
Cheers,
Wes

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It did, especially during the rush of mass training in 1940-early 1941. And Finns in Winter War pointed out the same as well.

XBe02Drvr said:

Didn't VVS pre-war training feature a deficit of all kinds of practice, not just gunnery? Didn't the Japanese in Manchuria in 1938 point out some pilot proficiency deficits in the VVS?
Cheers,
Wes

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I think the Japanese provided those lessons to pilots in several air forces.

Dimlee said:

Edited in bold by me.
We probably should define "skill". Soviet pilots could be good in aerobatics but bad in tactics, better or worse in communication, gunnery, individual initiative, etc.. Then there were management skills at squadron and higher levels. And ability of skilled commanders to withstand pressure from less smart superiors (huge issue in Red Army overall). "Average quality" of VVS is hard to define, this is very complex subject and politically sensitive - yes, until today. My humble opinion (some of my fellow Russians will curse me): average qualification of individual in VVS remained below the counterpart in other major air forces, through all WWII (and probably for most period of Cold War as well). But from summer 1943 and on there was enough "higher than average" personnel to gain superiority, step by step.

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And if not previously said, quantity has a quality all of its own.

Cheers,
Biff

XBe02Drvr said:

What's to verify? It's a known and obvious fact. Getting the highest percentage of bulletstrikes into a target profile is going to occur if your guns are clustered together and shooting down the sightline to the target, even if there are variances in the trajectories. Witness the P-38 or the A-20/B-25/A-26 strafers. Convergence angle is minimal and is only in one plane, resulting in a much longer "sweet spot" rangewise where the bullet density is maximum. All it takes is one 37MM hit. Game over.
Not like "sawing away" at your target with multiple wing mounted .30s.
Cheers,
Wes

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This rather depends on the target, both it's size and what it is doing.

My own belief is that trajectory is somewhat overrated or over valued when dealing with aircraft gunnery. Maybe for shooting at small fighters it matters. When shooting at even medium bombers? you have hundreds of sq ft of wing area and fuselages that are 4 to 6 ft high.
The British were pretty poor in gunnery training pre-war and in the early part of the war when they instructed their pilots to open fire on target sleeves at 300yds they found that the pilots were sometimes opening fire at 800-1200yds.
You need a laser beam to to fix that "trajectory problem", not nose mounted guns.

Unless it is a head on pass or you are sitting directly on the target's "6" deflection shooting will be required to a greater or lesser extent.
for deflection shooting the time of flight is the more important aspect. If you are shooting ahead or behind (much more likely) the target trajectory doesn't matter.
I will grant that 'flat' trajectory gun will usually have a low time of flight compared to a high trajectory gun and so the terms can be confused.

Another problem comparing wing mounted guns is that at times "convergence" didn't really happen at any range. The British and perhaps others deliberately aimed the guns in a wide pattern to increase the chances of hit/s to compensate for the poor gunnery.
One "official" pattern for the Spitfire even had the 20mm cannon hitting at different heights so as the guns "crossed" over they formed a figure 8 pattern and not a circle or oval. And none of the machine guns were pointed where the cannon were pointed. what an individual pilot may have been able to do is different but unless assigned to one plane constantly mucking about with the "patterns" in different aircraft in the squadron wasn't likely to improve things overall.

Claiming that fuselage mounted guns were so much more accurate than wing mounted guns often does not take this into account.

When ground strafing the target is essentially stationary (even 30mph trains and trucks compared to 300mph aircraft) and firing starts further away than the convergence planed for air to air combat. You do need to allow for the pull out

The Russians and Germans had opposite problems with fuselage mounted guns, for the Russians their 12.7mm machine gun/s have a shorter time of flight than the 20mm cannon does. Not a problem at short range but at long range?
For the Germans the machine guns had longer times of flight than the prop mounted 20mm gun and the prop mounted 20mm gun used ammo of rather different ballistics. Again not a problem at short ranges (under 300 meters) but makes long range gunnery a bit of a joke.

XBe02Drvr said:

I beg to differ on the twitchiness angle. Twitchiness is usually a low speed/high AOA phenomenon, unless workmanship or shoddy materials has weakened flight controls. The Soviets praised the high speed controllability of the 'Cobra and used tactics that took advantage of it. The twitchiness comes into play when you are foolish enough to get into a high G, energy draining knife fight with a Zero at tropical air densities and altitudes where your aircraft is running out of steam. This also is where dealing with the three separate trajectories of your gun package is at its most vexing.
Now let's go to the forested plains of NW Russia. (NOT Siberia, BTW). Bitterly cold, air so dense you can cut it with a knife, one less trajectory to deal with, and all your remaining firepower boresighted line of sight. Combat is high speed, down low, and against fighters optimized for altitude, while yours has been carefully adapted and optimized for this environment, and flown by pilots used to living and fighting rough. What more could a poor, maligned venomous snake ask for?
BTW, the victory tallies in the Lend Lease article don't seem to show high kill numbers against LW bombers and transports. Looks like mostly fighters. 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

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Wes - Stuka's were rarely unescorted. Although agile, they were so slow that they could never disengage from a fighter of any current performance. The firepower of a 109E/F or G was far superior in range and destructive power. Any escape maneuver involved a desperate high G turn or even an initial dive which surely hampered the gunner.

If a Stuka initiates a turn too early, he gives the closing fighter a pretty easy (comparably speaking) deflection shot at fuel/pilot/engine. There was a reason that they converted to FW 190 as fast as they could.