The Kalinin K-7 (Russian: Калинин К-7) was a heavy experimental aircraft designed and tested in the Soviet Union in the early 1930s.
It was of unusual configuration, with twin booms and large underwing pods housing fixed landing gear and machine gun turrets.
The K-7 design had an intended capacity of 120 passengers and 7,000 kg (15,000 lb) of mail, or 112 fully equipped paratroopers when configured for military transport.
The aircraft completed seven test flights before a crash due to structural failure of one of the tail booms on 21 November 1933.
However, there appeared recently some speculation in the Russian aviation press about the role of politics and the competing design office of Andrei Tupolev, suggesting possible sabotage.