Designed by World War I aviator Konstantin Kalinin with a wingspan
greater than a B-52's and a much greater wing area, the K-7 was one of
the biggest aircraft built before the jet age. It was only one engine short of
the B-52 as well, having the curious arrangement of six pulling on the wing
leading edge and one pushing at the rear.
The K-7's very brief first flight showed up instability and serious vibration
caused by the airframe resonating with the engine frequency. The solution to
this 'flutter' was thought to be to shorten and strengthen the tail booms, little
being known then about the natural frequencies of structures and their
response to vibration. On the 11th flight, during a speed test, the port
tailboom vibrated, fractured, jammed the elevator and caused the giant
aircraft to plough into the ground, killing 15.
Undaunted by this disaster, Kalinin's team began construction of two
further K-7s in a new factory, but the vicissitudes of Stalin's Russia
saw the project abandoned, and in 1938 the arrest and execution
of Kalinin on trumped up espionage and sabotage charges.
Jim Winchester "The World's Worst Aircraft", 2005
FACTS AND FIGURES
© The K-7 was one of the
first metal aircraft with a
twin-boom layout.
© As originally designed the
K-7 was to have engines in
the undercarriage sponsons.
As completed the bomber
had gun positions, the bomb
load and an internal staircase
as well as two large wheels in
each massive sponson.
© The K-7's control surfaces
were all deflected by the use
of large trim tab surfaces
mounted on struts.
© The K-7 was said to have
had a pilot, 18 crew
members and one passenger
when it crashed, killing all
but five crew. It is not clear
what they all did, but no
doubt tending to the engines
was a full-time task.
Kalinin K-7 on YOUTUBE
