In 1941, the Polikarpov OKB began work on an Istrebitel' Tyazhely Pushechny - heavy cannon fighter - which was to mount a 37mm cannon between the cylinder banks of a 1,650hp Klimov M-107P 12- cylinder liquid-cooled Vee engine, and also carry two synchronised 20mm cannon. The aircraft was of mixed construction, the fuselage being a wooden monocoque and the wing of steel and dural. The first prototype, referred to as the M-1, was completed in October 1941, but difficulties with the engine delayed the initiation of flight testing until 23 February 1942. An M-107A replaced the M-107P late in 1942, but engine difficulties were still experienced, and a second prototype, the M-2, was completed with an AM-37 engine of 1,400hp with which it flew on 23 November 1943. The M-2 had an armament of three 20mm cannon and eight RS-82 unguided rocket projectiles, the engine eventually being replaced by an AM-39 of 1,700hp. Factory flight testing continued until June 1944 when the programme was abandoned.
Max take-off weight: 3570 kg / 7871 lb
Empty weight: 2960 kg / 6526 lb
Wingspan: 10.00 m / 33 ft 10 in
Length: 8.95 m / 29 ft 4 in
Wing area: 16.45 sq.m / 177.07 sq ft
Max. speed: 655 km/h / 407 mph
Range: 1280 km / 795 miles