P-39 fun info, techniques, experiences

[TP_Sparky]

I thought it'd be fun to share experiences with the P-39.  

 

First, some fun facts I'm learning in Dmitriy Loza's, Attack of the Airacobras.  The two doors were made by the Hudson car company under contract and both had windows you could open at any speed.  Both doors could be opened but not in flight (I'm presuming air pressure) but they had a handle inside and outside each door to jettison that door.  The left door was not recommended for use as throttle actuating rods ran by it.

 

Wing guns, when installed, discharged empty cartridge cases and ammo belt links below the wing but the two nose-mounted machine guns and the cannon cartridge cases emptied into a storage bin in the nose section (reportedly) so the a/c center of gravity didn't shift during firing weapons.  The rear-mounted engine caused enough center of gravity problems and any loss of weight forward of the c/g would exacerbate this. 

 

The a/c had armor around the engine, oxygen bottles (Airacobra I) and pilot's cabin.  The pilot's was protected from behind by the engine and behind his head was 2.5 inches of bulletproof glass.  The deck beneath the pilot was an armored sheet and before him was bullet-proof glass 1.4 inches thick.  The propeller reduction gear was protected by five armor plates.  These also served to protect the pilot's cabin from the front.  Taken together the pilot was protected by armor from front and rear.

 

The biggest initial challenge was learning effective use of the "boxes".  Each P-39 had two radio transmitters and three radio receivers.  As pilots cooled their heels eagerly awaiting their squadron's compliment of P-39's to arrive at the transition training station they learned about the a/c and honed entirely new skills in radio use and prowords and brevity.  Some pilots feared this innovation would distract from air combat awareness but battle experience immediately showed its vital part in coordinating movement, attack and defense.

 

The tricycle gear delighted the pilots for ground handling.  One fact I found odd was "The aircraft could take off and land even on relatively soft dirt strips without fear of nosing over."  In my experience and general knowledge tailwheel a/c are better in soft dirt.  Nosewheel struts tend to sink in soft soil and could bend or snap and your nose pitches into the dirt.  

 

The transition to the P-39 coincided with the Kuban Campaign and the incorporation of wide-scale tactical and operational innovation in the Soviet Air Force.  Two ship and four ship formations, widespread use of radios tactically and to vector formations, new and better a/c, and a host of other innovations that changed the Eastern Front Air War forever.

[Blackhawk_FR]

12 minutes ago, slparker17 said:

In my experience and general knowledge tailwheel a/c are better in soft dirt

Well, for tailwheel aircrafts, it depend how heavy is your tail / how close the CG is from the rear limit. And of course, how wet is the ground.

Edited March 13, 2018 by F/JG300_Faucon

[Ehret]

Soviets tended to remove machine guns from wings, but they might be useful for us, actually. They are grouped in close pairs and have higher rate of fire than ones mounted in the Spitfire. There is a mod to load 1000 rpg for them, too - a nice "spray'n'pray" ordnance. The only drawback is the trigger is (probably) shared with the nose 50cals and the latter have only 200 rpg.

Edited March 13, 2018 by Ehret

[TP_Sparky]

13 minutes ago, Ehret said:

The only drawback is the trigger is (probably) shared with the nose 50cals and the latter have only 200 rpg.

 

I'll probably remove my wing guns to be historical but it's be nice to have some wing gun ammo remaining as a reserve in case you get jumped after you exhaust your 37mm/.50 cal. ammo and are returning to base.

[Ehret]

Quite the amount when you load 1000rpg! Over 650rpg and 30s firing time, once the 50cals are empty.

Edited March 13, 2018 by Ehret

[Tag777]

Soviet pilots removed the wing's guns because they considered that the nose guns and the cannon were enough to knock down any german plane, and that increase the roll rate, too.

[TP_Sparky]

Yes and since their primary mission was air to air anything that increased agility in dogfighting was primary.

[TP_Sparky]

The Soviets were troubled by their fighters inability to bring down German bombers, hence the progressive increase in size and number of armaments.  The P-39's 37mm cannon could easily down bombers and a single 37mm cannon shell could destroy German fighters.  

 

Despite Russian reluctance to credit foreign arms, the P-39 answered two Russian prayers at exactly the right time.  First, the heavy armament.  Yes, slow firing and limited ammunition but lethal against German bombers that previously proved difficult to down.  No more. 

 

Second, at the moment the Soviets decided to adopt widespread use of radios like their German foe the P-39 gave them two transmitters and three receivers in every a/c.  Previously, a leader MIGHT have a radio, and if he they did, it MIGHT or might not function.  The U.S. radios worked and every pilot could listen on three nets and talk on two.  The down time awaiting aircraft allowed endless classes studying a/c systems, radio operations, PROWORDS (like the equivalents of "roger, over, wilco", etc.) and most important net discipline to decrease excited chatter and keep the channel open. 

 

After a couple months in the manuals and classroom from oh-dark-thirty to lights out the Soviet pilots were ready to operate their new P-39's in new tactical formations with new radio communications procedures.  In a way, the delivery delay insured Soviet pilots were ready for their a/c when their squadron allotment finally arrived from Persia.

[SCG_motoadve]

Does the P39 has the same engine as the P40?

[=362nd_FS=RoflSeal]

14 minutes ago, II./JG77_motoadve said:

Does the P39 has the same engine as the P40?

No better in game terms

1560hp for 2 minutes, 1325hp for 5 mins, 1150 hp for 15mins vs 1150hp for 5 mins

[SCG_motoadve]

Glad to see that.

 

[Ehret]

Just now, RoflSeal said:

No better in game terms

1560hp for 2 minutes, 1325hp for 5 mins, 1150 hp for 15mins vs 1150hp for 5 mins

 

If the throttle is similar to the P40', then even higher power may be available, although briefly.

[A_radek]

7 hours ago, 19//Rekt said:

And a manifold pressure regulator, right?

I don't think we know that yet. I believe that rumor started because Han omitted specifically writing it lacked one in the aircraft spec sheet. 

[TP_Sparky]

I've flown the P-39L a few times.  I removed wing guns.  She has interesting stall characteristics. 

[Mauf]

1 hour ago, slparker17 said:

I've flown the P-39L a few times.  I removed wing guns.  She has interesting stall characteristics. 

 

I have noticed a strange tendency to become unstable in flight after recieving even a few 8mm hits (few bullet holes on wing, no tech chat damage reported). Wobbling could almost be described as violent jerking on random axis (primarily roll by the feel of it). Can you report the same? P39 overall feels very unstable but nimble.

[-332FG-Hank_DG]

3 minutes ago, Mauf said:

 

I have noticed a strange tendency to become unstable in flight after recieving even a few 8mm hits (few bullet holes on wing, no tech chat damage reported). Wobbling could almost be described as violent jerking on random axis (primarily roll by the feel of it). Can you report the same? P39 overall feels very unstable but nimble.

 

I can report the same thing. Although my fuel tank was hit and i was streaming, no apparent holes in the wings or tail. Intense wobble and unstable. Also whenever i got shot in the engine, failure would occur within 10 seconds.

[Mauf]

Okay, so it's not just my imagination. What I find weird is that it's so jerky. I would expect drag that would be constant, even with fuel leaking. I shall henceforth call my P39 "Flipper".

[TP_Sparky]

40 minutes ago, Mauf said:

 

I have noticed a strange tendency to become unstable in flight after recieving even a few 8mm hits (...no tech chat damage reported). ...P39 overall feels very unstable but nimble.

 

I set mine on invulnerable just to get a feel for the a/c as if I were dogfighting with a squadron mate to explore the new a/c characteristics.   

 

I'm used to a Yak-1b and later flew a La-5FN Series 2 and I was manuvering my P-39L vs. a Me-110 and oddly it seemed my P-39 couldn't turn worth a darn without entering an accelerated stall that was difficult to exit.  The 110 seemed to consistently out-turn me.  I'd have eaten him up in a moment in the Yak or the La-5FN but the P-39 seemed to have terrible turning performance even compared to a Me-110!  And yes, I removed the wing guns before I flew her.

 

The program simulates the onset of stall buffet so I tried flying "on the tickle" (on the edge of the stall) to maximize performance but she'd fall out of the turn in an accelerated stall or a spin and I'd baptize the airframe in the Kerch Strait.

[Mauf]

24 minutes ago, slparker17 said:

 

I set mine on invulnerable just to get a feel for the a/c as if I were dogfighting with a squadron mate to explore the new a/c characteristics.   

 

I'm used to a Yak-1b and later flew a La-5FN Series 2 and I was manuvering my P-39L vs. a Me-110 and oddly it seemed my P-39 couldn't turn worth a darn without entering an accelerated stall that was difficult to exit.  The 110 seemed to consistently out-turn me.  I'd have eaten him up in a moment in the Yak or the La-5FN but the P-39 seemed to have terrible turning performance even compared to a Me-110!  And yes, I removed the wing guns before I flew her.

 

The program simulates the onset of stall buffet so I tried flying "on the tickle" (on the edge of the stall) to maximize performance but she'd fall out of the turn in an accelerated stall or a spin and I'd baptize the airframe in the Kerch Strait.

 

Weird, I found her pretty stable in the turn. Not a great turner but able to go with a 109 for a few seconds.  Roll rate is where it's at though it seems. What speeds did you turn at? I never let her go below 200 mph. Below 180 or so, it feels like a cork in the bathtub.

[TP_Sparky]

I'll have to see.  I was using the HUD kph.  One problem was my throttle only gave about 80% throttle fully opened at 3,000' AGL.  I didn't lift the throttles into burner (ha!) but I never have to do that to get Military power or Boost out of my Soviet a/c.  In my YAk or La-5 full throttle is 100%+ boost.  Full throttle in the P-39L is 80%.