Kalinin K7 Winged huge bomber, dream design of Soviet

Aircraft History and Specification

In 1925, Kalinin made a series of single-engined aircraft characterized by having a quasi-elliptical wing that made his OKB famous in the USSR. In 1930, he designed a gigantic transport aircraft, the K-7 which has seating capacity of 60 or 20 tonnes of cargo. The K-7 design caused attention from the Ministry of Aviation Industry. It was given permission for the prototype to be built, but with the role changed to a heavy bomber. The aircraft was completed and was taxied onto the runway in June 1933. When all the seven engines were run a serious vibration throughout the aircraft was noted, so the affected parts were quickly strengthened. In August 1933 the K-7 made the first flight. Continuous tests revealed fair flying characteristics. In November 1933, during speed runs at low altitude, resonance suddenly struck and the right tail boom fractured, The K-7 dived into the ground and burned. The USSR aviation leadership changed views on production of heavy aircraft. Kalinin was not allowed to complete the development of K-7. The scheme was abandoned in 1935.
Three other Kalinin experimentals also included