The OKO-7 was to have been a heavy fighter produced in the Ukraine region of the USSR in 1940 Designed to a 1940 VVS requirement for a heavy fighter, the OKO-7 was to have been powered by two I,500 hp Shvetsov M-90 (Ash-90) or two 1,380 hp Mikulin AM-37 engines, with armament of three 20mm ShVAK cannon and two 7.62mm ShKAS machine-guns. The OKO-7. was Tairov's last known design before he was killed in an air crash in December 1941.