P-39D-2 right nose weapon

[greybeard]

Hi!

I'm struggling to ascertain what was the real armament of this variant of the Airacobra; about half of sources state that it shared the HS 20 mm cannon with earlier D-1, whilst the other half state it reverted to the Oldsmobile M4 (a.k.a. T9) 37 mm cannon.

Which is the truth?

 

[Snautzer01]

Intended export version (RAF) the 20mm hs

 

[Shortround6]

Hi!

I'm struggling to ascertain what was the real armament of this variant of the Airacobra; about half of sources state that it shared the HS 20 mm cannon with earlier D-1, whilst the other half state it reverted to the Oldsmobile M4 (a.k.a. T9) 37 mm cannon.

Which is the truth?

This seems pretty good: Bell P-39D-1,2 Airacobra

In a book by Birch Mathews "Cobra" he lists 675 P-400s (or contracts for) 429 P-39Ds (with 37mm ) 186 P-39D-1s (20mm) and 158 P-39D-2s (37mm cannon) so the possibility for confusion is great.
What may have been done in the field by a particular squadron may also be subject to question. Given what the majority of aircraft in a unit may have been equipped with or the supply situation. This is speculation on my part as I have read nothing about gun swaps in teh field. Merely pointing out the possibility.

 

[tomo pauk]

The Soviet manual on the P-39 says that both D-1 and D-2 were with 20mm, but then again the US-bound D-2s might've had the 37mm instaled.

 

[FLYBOYJ]

Bell P-400/ Airacobra I

 

[Shortround6]

It is plausible that some of the P-39D-2s sent to Russia were either completed with 20mm guns or refitted with 20mm guns prior to shipment because up until then the P-400/P-39s they had gotten had 20mm guns and the introduction of the 37mm gun and ammo would have meant supply problems. With larger shipments of later P-39s and the establishment of better supply situation/s the change over could be made to the 37mm gun.
I don't know, just throwing it out there as a possibility.

 

[GregP]

They built some Curtiss Hawks with metric instruments, so refit of "standard? items was definitely happening in the industry, depending on what was ordered. It is not inconceivable that some D-1s and D-2s were built with different cannons from one another ... though I'd expect at least a different dash number if the production line had a change order incorporated. At least, that is what USUALLY happened.

That is not to say that exceptions didn't occur, they did.

 

[greybeard]

Sorry, I forgot to specify that I had in my mind Russian Airacobra when asking.

So, the Soviet manual should be a good clue, supported by the plausible hypothesis to avoid supply problems by retaining the 20 mm weapon.

I found a good article about ("The P-39D-2 in the Soviet VVS"); unfortunately, it does not mention its armament. The only drawing there represents an M1 armed example, though.

Same opinion is of Massimo Tessitori on his "P-39 Airacobras in VVS", where he interestingly details visual differences among early 37 mm delivered without protecting cover, later with, and long barrel of the 20 mm. Indeed, looks to me easy to confuse early 37 mm without cover

with "long barrelled" 20 mm.

although he rightly points out: "It could be said in general that if "short simple barrel" is going through spinner it should be 37mm cannon and if "something long with complicated barrel" is going through spinner it should be 20mm cannon."

This doesn't mean that some, many or even all P-39D-2 couldn't be fitted with the Oldsmobile weapon, also by retrofitting; just trying to depict what I think to have understood.

Thanks gentlemen for your kind replies.

Cheers,
GB

 

[XBe02Drvr]

According to my dad, who worked at Bell Niagara in '44, they were building planes with the "big cannon" for the Russians, who were not happy, because they preferred the "small cannon". Now what my dad knew or cared about planes or guns wouldn't quite fill a small thimble, so you can decide how many grains to take with that. He said some of the Soviet procurement officers who hung around the plant were pretty colorful characters.
Cheers
Wes

 

[greybeard]

"...my dad, who worked at Bell Niagara in '44..."

Thanks, Wes, for your contribution.

Indeed, I was speaking of variant D-2, built and ferried in 1943, that then fought in the Kuban and Kursk during spring-summer of same year.

I think in 1944, when your father was working at Bell, probably they built later models (K, L, M, N, Q), all fitted with the 37 mm cannon.

Cheers,
GB