Kalinin K-7
The Soviet Union started constructing this aircraft in 1931. They called it the Kalinin K-7. Konstantin Kalinin, a World War I aviator and aircraft designer, came up with the idea. It was one of the largest aircraft ever made at the time, with a length of 91 ft 10 in (28m) and a wingspan of 173 ft 11 in (53 m). It had an engine in the pusher configuration, six tractor engines on the wing leading edge, and underwing pods, twin booms, and machine-gun turrets. The K-7 had seven flights before structural failure resulted in it crashing. The Soviets canceled the project in 1935.