Vsyevolod Konstantinovich Tyrov (thus pronounced, but written in Russian as Tairov, hence designations) was lecturer at MAI (Moscow Aero Inst.) 1930-39, and first deputy to Polikarpov. Formed OKO at Kiev, managing following until killed in crash December 1941: OKO-1 transport (October 1937), 7 passengers, 730-hp M-25A; OKO-4 sesquiplane fighter/bomber; Ta-1 (OKO-6) long-range escort (31 December 1939) with heavy armament and 2 x 1,100-hp M-88R, developed into excellent Ta-3 when Tyrov killed. OKO-7 heavy twin-engined fighter never completed.