The Kalinin K-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. In the passenger version, seats were arranged inside the 2.3-meter thick (7 ft 7 in) wings. The original design called for six engines in the wing leading edge but when the projected loaded weight was exceeded, two more engines were added to the trailing edges of each wing, one right and one left of the central passenger pod.

The K-7's very brief first flight showed up instability and serious vibration caused by the airframe resonating with the engine frequency.On the eleventh flight, during a speed test, the port tail boom vibrated, fractured, jammed the elevator and caused the giant aircraft to plunge to the ground, killing 15. The K-7 was yet another example of the aviation policy dictated by the infant Soviet regime, which believed that the way to impress the rest of the world was to build aircraft bigger than anyone else's.