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

[Dimlee]

I read years ago in a link I can no longer find that RAF 601 squadron had a Russian aviation expert attached to them when they were using the P-39. So when the P-39 arrived in Russia they had a good idea of what to do to make it a success. (Maybe Dimlee can help with this). Did Bell have their own test pilots or any real feedback from pilots in the field? I just cant understand why this CoG issue went on throughout the war, with Bell designing a replacement for the P-39 and designing in the same ffing problem.

No, I never heard about a Soviet expert in RAF 601. Interesting story, if it's true.

 

[buffnut453]

It goes to show that if someone has a belief you cannot discuss things with them, because that have a belief. That belief encourages them to make wild assumptions and statements that support that belief because they need something to support the belief. To them it's logical and simple. How many times in the threads have the changes to armour, COG, installing new engines been described as 'simple' and 'obvious' and any evidence to the contrary more, or less ignored.

The evidence is irrelevant as they have a belief. When the evidence is against them, they often change the subject and ignore the unanswered questions. Partly because they know that they cannot supply the answers, but to recognise that would dent the belief and that cannot be allowed to happen.

You will notice that at the start of all this there was a recognition from P39 that the aircraft was better at low/medium altitude than higher up, which is true, it is better lower down. The problem was that he believed that it was supreme at low / Medium altitude which it clearly isn't. Now that has been proved beyond any shadow of doubt, he is now trying to pretend that it was better at 25,000ft, which a) it clearly isn't and b) Is contrary to his initial premise that it was better at lower altitude.

DENY EVERYTHING, BALDRICK!!!

 

[Glider]

No, I never heard about a Soviet expert in RAF 601. Interesting story, if it's true.

I doubt that this is true, it would have been published if its true. Also if the first P39's the Russians had were the hand me downs from the UK ones which we rejected. How could there be a Russian expert?

 

[FLYBOYJ]

It goes to show that if someone has a belief you cannot discuss things with them, because that have a belief. That belief encourages them to make wild assumptions and statements that support that belief because they need something to support the belief. To them it's logical and simple. How many times in the threads have the changes to armour, COG, installing new engines been described as 'simple' and 'obvious' and any evidence to the contrary more, or less ignored.

The evidence is irrelevant as they have a belief. When the evidence is against them, they often change the subject and ignore the unanswered questions. Partly because they know that they cannot supply the answers, but to recognise that would dent the belief and that cannot be allowed to happen.

You will notice that at the start of all this there was a recognition from P39 that the aircraft was better at low/medium altitude than higher up, which is true, it is better lower down. The problem was that he believed that it was supreme at low / Medium altitude which it clearly isn't. Now that has been proved beyond any shadow of doubt, he is now trying to pretend that it was better at 25,000ft, which a) it clearly isn't and b) Is contrary to his initial premise that it was better at lower altitude.

The belief that the P39N was some kind of wonder weapon ignores the fact that was little more than a twice around the airfield before it runs out of fuel fighter, ( a little harsh I know but you get the picture). The fact that a Typhoon could lug 2,000lb bombs further that the P39N can go clean sort of proves the point. I would expect the P51 to do something similar and the P40 probably has a better payload range. In fact the P39N doesn't really have much of a payload.

Why was the P39Q pretty much the last production version of the P39 if the P39N was so good?. I don't actually know the detailed reasons but we can assume it was because it was an improvement including the increase in fuel. The users were happy to accept the lower performance for those advantages, which tells me that there was something wrong with the P39N.

Perfect! And lastly, why did General George Kenny, 5th AF do away with all of his P 39's from front line units in favor of the P 38? Why is it that some of the very talented pilots of the 80th Fighter Group struggled to attain any significant kills with the P-39 but when P 38 operations began in late 1942, the kills skyrocketed?

 

[pbehn]

I doubt that this is true, it would have been published if its true. Also if the first P39's the Russians had were the hand me downs from the UK ones which we rejected. How could there be a Russian expert?

I read it ages ago on t'internet but cant find it now. Churchill offered help to the Soviet Union almost immediately after Germany invaded. There was a long time passed between Germany invading Russia and P-39s being put on ships. The article was mainly concerned with why the VVS enjoyed much better service with it than other forces. Mainly it was about using it to do things it could do, not things it couldnt, and being as well prepared for the Eastern Front as possible, which started before the planes were shipped.

 

[GrauGeist]

Perfect! And lastly, why did General George Kenny, 5th AF do away with all of his P 39's from front line units in favor of the P 38? Why is it that some of the very talented pilots of the 80th Fighter Group struggled to attain any significant kills with the P-39 but when P 38 operations began in late 1942, the kills skyrocketed?

It's obvious that the Japanese weren't afraid of the P-38.
But when they heard the fearsome P-39 was in the area, they ran for shelter.

This is clearly the reason behind the disparity in claims between the two types...

 

[FLYBOYJ]

It's obvious that the Japanese weren't afraid of the P-38.
But when they heard the fearsome P-39 was in the area, they ran for shelter.

This is clearly the reason behind the disparity in claims between the two types...

View attachment 624839

I believe that was straight out of the flight manual!

 

[pbehn]

Dimlee Not the article I read, but this does state Soviet pilots were training with 601 squadron, not unreasonable to think they had a senior person in charge of it all.

Airacobras in the Soviet Union
Quote. Soviet pilots had first seen the Airacobra in Great Britain, when a group of pilots was sent to No. 601 Squadron at RAF Duxford for training. The British had found the Airacobra unsuitable for their own use and were more than happy to turn over their Airacobras to the Soviets, and some 212 of the 675 Airacobra Is ordered by the RAF were diverted to the USSR. The Airacobras first entered service with the Soviet Air Force in May of 1942.

 

[Glider]

Dimlee Not the article I read, but this does state Soviet pilots were training with 601 squadron, not unreasonable to think they had a senior person in charge of it all.

Airacobras in the Soviet Union
Quote. Soviet pilots had first seen the Airacobra in Great Britain, when a group of pilots was sent to No. 601 Squadron at RAF Duxford for training. The British had found the Airacobra unsuitable for their own use and were more than happy to turn over their Airacobras to the Soviets, and some 212 of the 675 Airacobra Is ordered by the RAF were diverted to the USSR. The Airacobras first entered service with the Soviet Air Force in May of 1942.

Interesting information and something I hadn't heard before. I admit my first thought was the most senior person would probably be the NKVD Commissar, but that's just me.

 

[Shortround6]

Alternative method for figuring fuel burn in combat at 25,000ft for the P-39.
Take power at 14,600ft (1150hp) divide by fuel burn (147 gallons an hour) for 7.82hp per gallon, rounded down.

Find HP in performance reports At WW II Aircraft Performance.
770hp at 25,000ft in high speed level flight. Divide by 7.82 and you get 98.46 gallons an hour or 32.8 gallons for 20 minutes.
Not as high as my early estimate but higher than 24 gallons for combat for 20 minutes.

 

[pbehn]

Interesting information and something I hadn't heard before. I admit my first thought was the most senior person would probably be the NKVD Commissar, but that's just me.

The introduction and operation of Hurricanes is better documented. There was an agreement to provide the planes and a nucleus of pilots and staff to get things running. Just from looking at 601 squadron history maybe the same was done with the P-39 but in UK. 601 only did two operations on 9-11 October 1941, it was taken off operations in December but 601 didnt switch to Spitfires until March.

 

[glennasher]

Alternative method for figuring fuel burn in combat at 25,000ft for the P-39.
Take power at 14,600ft (1150hp) divide by fuel burn (147 gallons an hour) for 7.82hp per gallon, rounded down.

Find HP in performance reports At WW II Aircraft Performance.
770hp at 25,000ft in high speed level flight. Divide by 7.82 and you get 98.46 gallons an hour or 32.8 gallons for 20 minutes.
Not as high as my early estimate but higher than 24 gallons for combat for 20 minutes.

Could the Bell even fight at 25,000 feet?, it seems like it wouldn't be worth the trouble to get to that altitude, and have the poor performance as indicated.

 

[pbehn]

Could the Bell even fight at 25,000 feet?, it seems like it wouldn't be worth the trouble to get to that altitude, and have the poor performance as indicated.

The Airacobra I was powered by an Allison V-1710-E4 twelve-cylinder V in-line engine rated at 1150 hp for takeoff. Weights were 5462 pounds empty and 7845 pounds normal gross. Maximum speeds were 326 mph at 6000 feet, 343 mph at 10,000 feet, 355 mph at 13, 000 feet, 341 mph at 20,000 feet. Initial climb rate was 2040 feet per minute. With an internal fuel capacity of 100 Imp gal the Airacobra had an endurance of 1 hour 20 minutes at maximum continuous cruising speed at 6000 feet, 1 hour 5 minutes at 12,000 feet, and 1 hour 35 minutes at 20,000 feet. The true airspeeds at these altitudes were 287 mph, 327 mph, and 308 mph, respectively. Under most economical cruise conditions, the endurance increased to 3 hours 20 minutes, the relevant speeds being 183 mph at 6000 feet, 217 mph at 12,000 feet, and 215 mph at 20,000 feet. Under maximum continuous climb conditions, it took 15 minutes to reach 20,000 feet. The operational ceiling was considered to be about 24,000 feet, although there was a marked decrease in performance above 20,000 feet. At the Airacobra's rated altitude of 13,000 feet, it was 18 mph faster than the Spitfire VB. However, the speed fell off rapidly above that height, and the two planes were almost exactly matched at 15,000 feet. At 20,000 feet, the Spitfire VB was 35 mph faster and at 24,000 feet it was 55 mph faster. The ground run of the Airacobra during takeoff was 2250 feet, as compared with 1470 feet for the Hurricane II and 1590 feet for the Spitfire V.


Airacobra I for RAF, P-400

 

[Juha3]

Juha - do you know how many claims P-39 were recorded by the VVS? I'm trying to find data for Soviet P-39 claims vs Luftwaffe claims of P-39s

Hello Flyboyj
sorry, no. All i can say is that the pilots of 9 GIAD, the Fighter Division whose pilots were credited highest number of kills of the P-39 equipped divisions and also probably of the all VVS fighter divisions, scored 1147 aerial kills. This according to Mellinger. But IIRC the highest scoring P-39 regiment was only the 3rd in regimental ranking.

 

[FLYBOYJ]

Hello Flyboyj
sorry, no. All i can say is that the pilots of 9 GIAD, the Fighter Division whose pilots were credited highest number of kills of the P-39 equipped divisions and also probably of the all VVS fighter divisions, scored 1147 aerial kills. This according to Mellinger. But IIRC the highest scoring P-39 regiment was only the 3rd in regimental ranking.

Thank you!

 

[Juha3]

Could the Bell even fight at 25,000 feet?, it seems like it wouldn't be worth the trouble to get to that altitude, and have the poor performance as indicated.

At lest Ns and Qs could, see the message #1,569. One reason why some of them were allocated to PVO units, as air defense interceptors.

 

[Juha3]

A bit OT but the top three VVS fighter regiments, 402 IAP 810 kills, notice, in spite of its achievements it did not get the Guard title. At the beginning of the Great Patriotic War equipped with MiG-3s, then with different Yaks.
5 GIAP (ex-129 IAP) 735 kills, I-16, MiG-3, LaGG-3, La-5 and at the very end of the war La-7
16 GIAP (ex-55 IAP), 697 kills, notice, not all under 9 GIAD with P-39s but was equipped before that period with I-153s/I-16s/MiG-3s at the beginning of the war (was converting from older fighters to MiG-3s), then Yak-1s before converting to P-39s at the beginning of 1943.

 

[Shortround6]

Our Expert is claiming a number of things.
One is that the P-39N seems to have been the answer to most of the allies fighter requirements.
Early P-39s, Aircobra I/P-400s used 8.80 supercharger gears and had about 1150hp at 12,000ft.

Since the later P-39N had 9.60 supercharger gears and was supposed to make 1125hp at 15,500ft (why the flight operation chart for the P-39N says 14,600ft I don't know) this seems to transform the P-39 from a fighter that struggled at 20,000ft and above to one that could take on or perform nearly as well as any fighter in the world in 1943 at well above 20,000ft.

Sometimes I apply the "smell" test.
P-39 with the uprated engine had about 770hp at 25,000ft including RAM for a plane that weighed about 7000lbs or bit more (depending on fuel burn off)
P-51B had an engine that gave 1300hp at 26,400ft no ram and 1300hp at 32,000ft with ram at military rating for a plane that went just under 9000lbs with 1/3 of it's fuel burned off.
P-51B using WER had 1410hp at 29,300ft with ram.

P-51B had 180 gallons internal and was rated at a 150 mile combat radius.
Our Expert is claiming that the P-39 with 2/3rds the fuel could do as well???

 

[FLYBOYJ]

Our Expert is claiming a number of things.
One is that the P-39N seems to have been the answer to most of the allies fighter requirements.
Early P-39s, Aircobra I/P-400s used 8.80 supercharger gears and had about 1150hp at 12,000ft.

Since the later P-39N had 9.60 supercharger gears and was supposed to make 1125hp at 15,500ft (why the flight operation chart for the P-39N says 14,600ft I don't know) this seems to transform the P-39 from a fighter that struggled at 20,000ft and above to one that could take on or perform nearly as well as any fighter in the world in 1943 at well above 20,000ft.

Sometimes I apply the "smell" test.
P-39 with the uprated engine had about 770hp at 25,000ft including RAM for a plane that weighed about 7000lbs or bit more (depending on fuel burn off)
P-51B had an engine that gave 1300hp at 26,400ft no ram and 1300hp at 32,000ft with ram at military rating for a plane that went just under 9000lbs with 1/3 of it's fuel burned off.
P-51B using WER had 1410hp at 29,300ft with ram.

P-51B had 180 gallons internal and was rated at a 150 mile combat radius.
Our Expert is claiming that the P-39 with 2/3rds the fuel could do as well???

I also think he is mixing and confusing information from the P-39N manual and the P-39Q manual. Both manuals show internal fuel capacity of 87 gallons in the weight and balance charts. I see no reference of 120 gallons.

He is correct about the IAS/ TAS conversion table only found in the P-39Q manual. With no instruction to convert in the earlier manuals, I think there was the source of some confusion (as you pointed out earlier).

Bottom line, I think with some of the numbers shown, the P-39 had a dismal high altitude intercept radius.

 

[Thumpalumpacus]

Are we cruising at 25000ft? Then combat should be at 25000ft.

That doesn't follow. What if the enemy is climbing up to you? Are you gonna wait 'til they get to your altitude before attacking? And if you don't get shoot-downs on the first diving pass, aren't you still flying and fighting at a lower level?

This is a non sequitur. Combat altitude and cruise altitude are not necessarily the same. Sloppy thinking, ten yards and loss of a down.