I-320(R), A.I.Mikoyan/M.I.Gurevich

28k b/w photo of the R-2 "History of aircraft construction in the USSR", Vol.2 p.321

Twin-engined all-weather heavy fighter-interceptor. Its electronic equipment was quite advanced for the historic period, so wide cockpit provided room for two side-by-side seated crew members. Cockpit was protected by 105mm thick bullet-proof glass with electric heating. Thin swept wing (35°) was optimized for high speed. Two soft fuel tanks were located inside the fuselage.

The engines were fitted in tandem:

• one engine in the nose, exhausting just after the the cockpit.
• another engine behind the center of the fuselage and exhaust under the tailfin.

A circular nose intake was used with a radar cone on the upper lip. Three cannons with 50 shells/gun (later 60) were fitted symmetrically under the front section of the fuselage.

Two I-320 were built - R-1 with RD-45F and R-2 with VK-1. The R-2 also differed by raised crew seats to improve view. Emergency ejection system was modified, de-ice equipment was installed on the wing and tailplane. Air intake channels had electric heating system to prevent ice buildup.

The R-1 was flown first on April 16, 1949. Flights by A.A.Vernikov, Akhmet-khan Soultan (factory trials) and Yu.A.Antipov (state acceptance trials) proved that aircraft is a success. Performance was adequate to solve tasks of night all-weather interceptor. The R-2 was flown in 1950 (same pilots plus M.L.Gallay and S.N.Anokhin). It had stronger wing, skin and equipped with airdynamic interceptors.

I-320 (both R-1 and R-2) was capable to takeoff with only one (any of two) engines running. But 17% thrust gain of the VK-1 failed to provide speed increase... Speed was limited by elasticity of thin wing and danger of flatter. Despite R-2 had strengthened wing with extra airdynamic fences, critical flatter speed was not changed substantially.

The Yak-25 was preferred as superior - for 1950 I-320 speed limitations were found unacceptable.