I can see either the P-39 Airacobra or P-63 Kingcobra added to the game.
But since half the P-39's, and nearly all the P-63's went to Russia, and as a nod to Lend-Lease, I'd prefer to see either in the Russian planeset with Soviet markings.
For P-39, Skin of Aleksandr Ivanovich Pokryshkin (Allies second highest scoring Ace) plane would be appropriate; 55th Fighter Regiment possibly, but not sure if that's where he served most of the War or not.
Some accounts, as well as papers of Pokryshkin himself, place him in the P-63 later in the war, but nothing definite.
How do you model the tendancy for the plane to be unrecoverable from a flat spin?
weight distribution of the P-39 supposedly is the reason for its tendency to enter a dangerous flat spin — a characteristic Soviet test pilots were able to demonstrate to the then-skeptical manufacturer who had been unable to reproduce the effect. After extensive tests, it was determined that the spin could only be induced if the plane was improperly loaded, with no ammunition in the front compartment. The flight manual specifically noted that one had to ballast the front ammunition compartment with the appropriate weight of shell casings to achieve a reasonable center of gravity.
P-39 Maiden flight = April 1939 Introduced = 1941 Produced = 1940-May 1944 Number built = 9,584
P-63 Maiden flight = 7 December 1942 Introduced = October 1943 Produced = 1943-1945 Number built = 3,303 (2,397 to Russia)
What's the date limitations to Early War and Mid War? I'm thinking, because the P-63 fixed a lot of the problems with the P-39 (except the flat spin), why not the P-63 over the P-39.