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

michaelmaltby · Sep 7, 2020

".... Did they successfully defend the Stukas and fighter bombers against the Yaks and P-39's?" The answer is NO."

However, I would argue, the P-39 in the hands of Soviet experten, was as good as any Soviet fighter AC that faced the Germans. There were very extensive air battles over the Crimea and Kuban after which the Soviets ultimately achieved air superiority. Spitfires and P-39s were the principal Soviet fighter AC in that theater, IIRC

MIflyer · Sep 7, 2020

michaelmaltby said:
However, I would argue, the P-39 in the hands of Soviet experten, was as good as any Soviet fighter AC that faced the Germans. There were very extensive air battles over the Crimea and Kuban after which the Soviets ultimately achieved air superiority. Spitfires and P-39s were the principal Soviet fighter AC in that theater, IIRC

I would agree with you. Note that when The Soviets brought in Yak-3's and 9's and LA-5N's they did not replace the P-39's but other fighters instead.

Here is a picture that says a lot about the P-40. It was taken near the Aleutian Islands. Note that there are short tailed P-40's that can only be E models that must have gotten there in 1942. One even has what looks like the Aleutian Tiger paint that Chennallt's son led. Also note there are are P-40N's, which did not start to come off the production lines until March 1944. The P-40N-5 with the first clear section behind the cockpit came out even later than March of 44. So we are looking at some E models that had to have been in that very harsh combat environment for at least 2 years.

In one of Edwards Parks's books about his WWII experience, a friend flying with a P-40 unit stopped by for a visit at his P-39 unit in New Guinea and said, "I don't know when we will get any new airplanes. These just won't wear out!" The P-40 had some significant faults and a number of serious inadequacies, but it clearly was one damned durable airplane.

By the way, for you modelers, the AMT 1/48 P-40N is one of best kits to get. With not too much work you can build any Allison engined variant, since it has the long tail and a choice of either an original style "razorback" or clear aft fuselages.

HAPPY LABOR DAY!

pinsog · Sep 7, 2020

The P39 at Guadalcanal was mainly used as a ground attack aircraft against ships, barges and troops. The 37mm cannon was supposedly very effective against barges. The lack of range wasn't a problem as I recall one pilot didn't bother to raise his landing gear between taking off and strafing a Japanese supply ship or barge.

One big difference between the P39 and most other American fighters was that it was very vulnerable from behind. P40's, P47's, Wildcats, Hellcats, Corsairs and P38's were well known for being tough. The P39 with its engine in the back could be downed pretty easily, vs the other fighters with the engine in the front protected by all the armor and aircraft structure to the rear.

FLYBOYJ · Sep 7, 2020

P-400s were used at Guadalcanal as well

CORSNING · Sep 7, 2020

Here's my 2 cents worth:

Acheron said:
I would like to use the expertise of you other forum members to ask about more obscure aircraft.

For example, what do you have to say when comparing the P-39 vs the P-40? All I (think to) know so far:

- The US used the P-40, not the P-39.
As already pointed out the USAAF used both the P-40 & P-39/P-400 extensively.
They were available.

- Both had poor high-altitude performance.
Correct, good aircraft up to about 15,000-16,000 ft.

- The P-39 had the engine behind the cockpit and could field a big 37-mm gun in the front.
Correct, and the Russians like the concentrated fire of the 37mm/twin 0.5 in. guns.

- According to wikipedia, the P-40 had the stronger engine.
The P-40's was better protected. Not sure about stronger. Although the Allison -85
of the P-39N/Q was rated at 1,420 hp. while the Allison -81 of the P-40N had a
maximum rating of 1,480 hp. both using 57"Hg boost.

- Also according to wikipedia, the P-39 was faster than the P-40, though this could easily be due to comparing different versions or altitudes.
This question brings up one of my favorite comparisons. The contemporary P-39N vs. P-40N
vs. P-51A (which Allison -81 was also rated at 1,480 hp. max.
http://www.wwiiaircraftperformance.org/P-39/P-39N_level-speeds.jpg
http://www.wwiiaircraftperformance.org/mustang/P-51A-1-43-6007-Chart-1400.jpg
P-39N: Best climber, P-40N: The most maneuverable & P-51A: The speed champion.

Otherwise, I would assume the P-39 to be preferred over the P-40.

The USAAF upper brass actually preferred the P-40 from what I have read.
1. It had a longer internal fuel range 750 ml. vs. 525 ml. in the N models.
2. It was more maneuverable.
3. It was more rugged and its engine was better protected.
I am sure there was more reasons, but that's the short take on the thread title.

Hope that helps Acheron.
, Jeff

Shortround6 · Sep 7, 2020

Acheron said:
Thank you!

One thing I recall, the Soviets reportedly claimed that the 37-cannon was great against the rugged FW-190. Having a radial engine, the FW-190 supposedly could take quite some punishment, but a 37-mm shell would ruin its day. I wonder though if 37-mm shells were considerably more destructive than 20-mm shells, anyone got any idea?

GregP and M MIflyer regarding the use of the P-39 in a round attack role, please let us know whether you are talking about the P-39 being used as a ground-attacker in its primarily role or ground-attacks on targets of opportunity. Given the normally low altitudes of Eastern Front air combat, the later could be significant, no?

Regarding the 37-mms destructive power vis-vis the Ju-87's gun, the Ju-87 was tasked with cracking the T-34's, right? To my knowledge, the Panzer III's and IV's were considerably lighter armored (or at least had much mess slope), especially early in the war. Any ides if the P-39's 37-mm could have been effective against these?

A US 37mm shell weighed 608 grams and contained 45 grams of Tetryl.
A 20mm Hispano shell weighed 130 grams and contained 10.2 grams of Tetryl (the were a number of similar shells). However the 37mm gun fired at 150-180 rounds per minute (book figure) vs the 20mm firing at around 600 rpm. A single 37mm shell was certainly destructive. the Problem was hitting the target with the low rate of fire gun (barges don't move very fast).

The Russians may have been impressed because the projectiles out of the 20mm ShVAK cannon went around 91-96 grams and contained 4.7 or 6.1 grams of RDX and aluminium.

For punching holes in armor you need velocity and the American 37mm didn't have a lot. The German 37mm used on the Stuka had about twice the potential energy with standard ammo and the Germans made AP rounds with tungsten cores. The US did not.

30mm of armor was generally considered the minimum needed to defeat 75mm HE ammunition from field guns or howitzers, this was generally the minimum specified for a "shell proof" tank (See British A10 for example) A 37mm HE round would have only a very small chance of disabling a tank with a single hit. AP shot for the field guns changed things. As did the proliferation of 37-47mm AT guns with high velocity AP rounds.

Hope that helps.

Acheron · Sep 8, 2020

C CORSNING and S Shortround6 thanks a lot, you are quite hellpful indeed

S Shortround6 where did you et the weight and explosive weight values from the shells? I am puzzled by what I read on wikipedia regarding German comparative cannons:
MK108: 330g shell, 85 g RDX
MG151/20: 57g shell, 3g "of HE"
Did shells of similar or even the same diameter vary that massively?

So the P-40 had superior maneuverability and range. The P-39s gimmick, the big 37-mm cannon, was overkill against fighters and due to lower RoF worse than lighter cannons. Would you folks agree with my assessment?

And do you think the 37-mm cannon might have been of use against heavy bombers (nevermind that the axis never got around to fielding these)? So even iof so, the poor altitude performance meant the P-39 as a whole would be useless I presume?

FLYBOYJ said:
P-400s were used at Guadalcanal as well

These were P-39s, correct?

pinsog said:
One big difference between the P39 and most other American fighters was that it was very vulnerable from behind. P40's, P47's, Wildcats, Hellcats, Corsairs and P38's were well known for being tough. The P39 with its engine in the back could be downed pretty easily, vs the other fighters with the engine in the front protected by all the armor and aircraft structure to the rear.

But, if one of these other aircraft got shot form behind, sure, the engine will be safer, but what about the pilot?

nuuumannn · Sep 8, 2020

Not wishing to add weight to either side of the discussion, but from a Commonwealth perspective, the P-40 was the fighter that the Commonwealth countries went to war with. For nations that were equipped with what can only be described as second rate equipment - and in the RNZAF's case truly museum piece quality; the only single-seat fighter the country had was an unarmed Gloster Grebe (!), the P-40 was a godsend and purposefully equipped the RNZAF, RAAF and RCAF in quantity and proved itself worthy of those forces' needs. Yes, the RAAF received Capstans and Mustangs, and the RCAF received FF-1s ( ) and Hurricanes and the RNZAF Corsairs, but it was the P-40 that held the line for all these air forces during the thick of the fighting.

As an aside it's worth noting that the P-39 has its own wee place in naval aviation history as the first tricycle undercarriage aircraft to operate from a British aircraft carrier. In 1944, a P-39 (sorry, Airacobra I) was used to assess the flexible deck concept the British were toying with and a landing was made on the escort carrier HMS Pretoria Castle on 4 April 1945. It was subsequently catapulted off; a notable first.

Tkdog · Sep 8, 2020

Capstan?

ah found it.
An explanation is here.

SaparotRob · Sep 8, 2020

Tkdog said:
Capstan?

Hey, it worked!

Tkdog · Sep 8, 2020

Indeed it did!

Tkdog · Sep 8, 2020

Obscure cigarettes aside, I wonder how much of an impact the tricycle landing gear had in regards to senior officer acceptance. It's another thing to have to train new pilots on.

Stig1207 · Sep 8, 2020

GregP said:
The Soviet Fighter Units were viewed by the Soviet high command as an extension of the ground Army. Their reason to be, in upper Soviet circles, was as support for ground operations.

The Luftwaffe tried coming in at high altitudes and the Soviets responded by ignoring the high-altitude German aircraft entirely and sending many aircraft at low altitude to attack the German ground troops. The Germans were faced with a simple decision: 1) Continue high-altitude attacks and suffer unsupportable ground casualties, or 2) Come down to low altitude and fight to save their ground troops. Without ground troops, there was no Operation Barbarosa. They chose to save their troops and the Soviet fighters got to dogfight with German fighters at low altitudes.

The P-39s were used as Soviet fighters. Yes, there was some ground attack involved, but the primary ground attack airplanes were Il-2 and Il-10 later on, with a few other Soviet attack types thrown in, such as the Pe-2 (outstanding) and Su-2 and others. The P-39s, P-40s, Spitfires, Hurricanes, P-47s, P-51s, etc. were mainly used to escort the attack planes in support of ground forces, so they primarily dealt with German fighters.

At first, Soviet equipment and pilots weren't very good. After mid-1941, it was hard for a Soviet fighter to live in a German sky over the Soviet Union, and many Germans racked up impressive scores quickly. The Soviets even had to move aircraft production more than 1,000 miles east to escape German bombing. But, by mid-1943, it was getting hard for a German pilot to live in a Soviet-controlled sky over the Soviet Union, Erich Hartmann notwithstanding (he got to the fight in Oct 1942). The La-5/7 were excellent, as were the Yak-3/9 series, and Soviet tactics caught up with the reality of situation. The German attacks in 1942 (Case Blue) and 1943 (Operation Citadel) were failures, helped by Russian weather, and resulted in the German retreat and eventual collapse.

At least, that is my current understanding from books and conversations with former VVS pilots and Russian internet contacts. I suppose it could be wrong ... but I'd need some evidence of it more than a few posts to think otherwise.

MIflyer said:
Certainly the Soviet P-39's could and no doubt did hit targets of opportunity in terms of ground attack. The 37MM was effective against thin skinned vehicles and I recall reading that a USAAF P-39 pilot in the Med described it was great for attacking barges, a 37MM round doing a good job of clearing the decks.

Now, the Soviets built a version of the Yak-9 that had a 45MM gun firing through the prop hub, for ground attack.

As Grep P says, there was no high altitude war in the East. Remember that neither the Germans nor the Soviets had high altitude heavy bombers in numbers that would represent even a decent airshow by US standards

But I recall that German ace Erich Hartmann said, "The P-39 performed like the BF-109 at low altitudes." That says a lot right there. It was not better than a 109, but it was in the ball game. On the other hand, the P-39 certainly was easier to land than the 109, especially the later "Beul" models. If the Soviets had been given all the 109's they wanted they would have been lucky to get one mission out of them with neophyte pilots.

And while Hartmann and some others racked up big scores against the Soviets, the real questions are, "Did they keep the IL-2's and Pe-2's off their ground troops? Did they successfully defend the Stukas and fighter bombers against the Yaks and P-39's?" The answer is NO.

Have a look at the disparity in strength between the Luftwaffe and Soviets:

Eastern Front Aircraft Strength and Losses 1941-45 .

It would seem a lot was being asked of the German fighter pilots, defending their ground troops, escorting bombers and ground attack aircraft over a long front line. Despite that, the Soviets were still losing 3 times as many aircraft in combat as the Germans were, after mid-43 and until the end of '44 .

pbehn · Sep 8, 2020

Tkdog said:
Obscure cigarettes aside, I wonder how much of an impact the tricycle landing gear had in regards to senior officer acceptance. It's another thing to have to train new pilots on.

Only in the heady world of an aviation write up would a capstan become an obscure cigarette.

FLYBOYJ · Sep 8, 2020

Acheron said:
These were P-39s, correct?

They were the export version of the P-39 with a 20MM cannon in the nose and 2 30 cal in the wings. The 20mm cannon was said to be more reliable than the 37mm cannon

CORSNING · Sep 8, 2020

The USAAF upper brass actually preferred the P-40 from what I have read.
1. It had a longer internal fuel range 750 ml. vs. 525 ml. in the N models.
2. It was more maneuverable.
3. It was more rugged and its engine was better protected.
I am sure there was more reasons, but that's the short take on the thread title.

Added tidbits;
Roll Rates (deg./sec.) P-39D/P-40F: 200mph: 63/85, 250 mph: 72/94.5, 300 mph: 62/94,
325 mph: 60/92. From NACA chart. The P-40 rolled faster at all speeds.
Turn Times (360 degrees/1,000 m): P-39N-1: 19.0 sec. vs. P-40N-1: 17.0 sec.
Dive: The P-40 could pull away from a P-39 in a dive fairly quickly (opinion formed from
all that I have read about both. The P-40N was a much lightened P-40 and dived a little
faster than the P-39N.
Acceleration: I believe it was in the book 'Forked-Tailed Devil' that I read that of the
Allison powered aircraft the P-38 was the drag king. The p-39 & P-51 were about even
and the P-40 brought up the rear. ( I was surprised when I read that the P-40E could
out accelerate a Spitfire V at low altitudes on the P-40E vs Spitfire V thread.)

Shortround6 · Sep 8, 2020

CORSNING said:
The P-40N was a much lightened P-40

Only the first couple of hundred (200?) P-40Ns were much lightened, later P-40Ns gained a lot of the weight back.
A number of the "light" P-40Ns gained weight back in the field as squadrons/local maintenance units added electric starters/bigger batteries, forward fuel tank, brought the number of guns back up to six and a few other changes. The Aluminium radiators/oil coolers and magnesium wheels stayed standard for the rest of production run and did shave some weight.

Shortround6 · Sep 8, 2020

Acheron said:
where did you et the weight and explosive weight values from the shells? I am puzzled by what I read on wikipedia regarding German comparative cannons:
MK108: 330g shell, 85 g RDX
MG151/20: 57g shell, 3g "of HE"
Did shells of similar or even the same diameter vary that massively?

The numbers are from "Flying Guns World War II" by Anthony G. Williams & Dr Emmanuel Gustin. Guns of different calibers varied considerably as the weight varied with cube of the diameter for projectiles of the same shape.
However the shape was often not the same, the Japanese army 20mm Ho-5 cannon used a short, stumpy projectile of 79 grams, it was the lightest 20mm projectile used in an aircraft cannon. The heaviest explosive 20mm projectile used in service was 136 grams.
Construction could also cause considerable variation. As an example the British changed to a fuse made of aluminum instead of brass post war for their 20mm cannon before the ADEN cannon. No other change and the weight dropped from 128-130 grams to 116 grams. Quality of the steel used governed how thick the shell walls needed to be as did the intended velocity of the shell, higher velocity shells need stronger walls to keep them from buckling when fired.
The Germans developed a new way of making shells, drawing the steel into a tube much like a cartridge case is drawn from a slug or short cup into a full length case. However the thin walls, while allowing higher explosive content, didn't provide much material for fragments. These were the famous mine shells like the MK 108 330 gram shell. The older shell used in the MK 101 (and MK 103) cannon weighed 433 grams and held 29 grams of explosive.
I would note that putting a tracer component in a shell often cut the HE content considerably so make sure you are comparing like to like.

Acheron said:
So even iof so, the poor altitude performance meant the P-39 as a whole would be useless I presume?

Maybe, most of the axis bombers didn't have very good altitude performance. The Japanese managed to attack with bombers well into the 20,000ft range but they weren't all that fast at high altitudes and their small bomb loads were also a handicap.

GregP · Sep 8, 2020

Hi Archeron,

You might try to Google "The Great Fighter Gun Debate" for gun tables. It goes a long way toward explaining the columns and numbers.

nuuumannn · Sep 8, 2020

Tkdog said:
Capstan?

The worst kept secret in Australia. Capstan was adopted as the code name for Spitfires being sent to defend the country.

Tkdog said:
I wonder how much of an impact the tricycle landing gear had in regards to senior officer acceptance. It's another thing to have to train new pilots on.

The RAF employed civilian tricycle undercarriage aircraft to train crews transitioning onto US types that entered the RAF, such as the Boston, Mitchell Liberator and Marauder. Specifically this one, the GAL Cygnet, which not only bears the distinction of being the first tricycle undercarriage aircraft built in Britain, but the first all-metal stressed skin monoplane lightplane built in Britain.

Cygnet

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

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