The Kalinin K-7 was designed by the Russian Army in the early 1930’s as an experimental Heavy Bomber aircraft that could also be used to transport civilians. Designed by World War I and civil war pilot Konstantin Kalinin at the aviation design bureau he headed in Kharkov. The K-7 was one of the biggest aircraft built before the jet age.
The K-7 relied on conventional prop engines since jet engine technology had not yet been invented. It had 20 engines in total, six propellers along the leading edge of each wing, another pair on the trailing. The bomber’s unusual twin boom configuration and under-wind pods, which housed the landing gear and machine gun turrets, actually seated up to 120 passengers inside the plane’s seven foot tall, 173 foot wide wings in addition to a crew of 11.
Even though the sheer size of it made it uneasy to the eye, the Russians put it to good use. Other that housing 120 passengers, it could drop 114 fully armed and ready paratroopers, carry 7 tonnes of mail, eight twenty millimetre cannons, eight seven millimetre machine guns and 9.6 tonnes of explosives. The aircraft was much more than its working, it was seen as a victory of the successful national steel industry.
During its first test flight, the super plan experienced serious in-flight instability. The K-7 did complete seven test flights, proving the plane’s ability to reach a 13,000 foot operational ceiling and a top speed of 140 mph. A crash in 1933, which killed 15 people in total and destroyed the aircraft, was widely speculated to be the result of sabotage and political intrigue, marked the end of the K-7’s development.