Most P-39s were used by the Soviet Air Force. The Soviet Air Force scored the highest number of individual kills attributed to any U.S. fighter type in the Eastern Front. The tactical environment of the Eastern Front did not demand the high-altitude performance needed by the RAF and USAAF.
Bell P-39Q Airacobra
The Bell P-39 had an innovative layout, with the engine installed in the center fuselage, behind the pilot, and the propeller connected via a long shaft. It was also the first fighter fitted with a tricycle undercarriage. Although it had an innovative design, the P-39 was handicapped by the absence of an efficient turbo-supercharger, preventing it from performing high-altitude work.