When the Soviet military wanted some heavy lifting done, they called in a Mil Mi-10 helicopter. This behemoth was a military transport helicopter developed from the more conventional looking Mil Mi-6. Designed in the late 1950s at the request of the Soviet government, the Mil Mi-10 (NATO reporting name Harke) was designed to carry its loads externally – unlike the Mi-6. This meant that it could carry larger cargo, and as the helicopter itself was lighter, it could also carry heavier loads.
The first prototype of the Mil Mi-10 helicopter was completed in 1959. It used the same engines and avionics as the Mi-6. But the fuselage was smaller and narrower. It also featured long, gangly legs which meant it could either taxi over its cargo, or the cargo could be maneuvered underneath for attachment. Inside the Mil Mi-10 helicopter there was space for up to 28 passengers, or up to 6,600 lbs (3,000 kgs) of cargo. The Mi-10 could carry up to 33,000 lbs (15,000 kgs) externally on its load platform.
The first flight of the Mil Mi-10 helicopter was on 15 June 1960. Testing continued uneventfully until May the same year, when the first prototype crashed killing everyone on board except for the navigator/radio operator. The cause of the crash was attributed to a problem with the gearbox.
The second prototype soon joined the test flight program and development continued. During testing the Mil Mi-10 helicopter broke several world records for altitude and payload for turbine powered helicopters. The helicopter was approved for production in 1961, although production didn’t start until 1964. 40 Mil Mi-10 helicopters were built from 1964 to 1969. Later a short-legged version called the Mi-10K was manufactured from 1974 to 1977. 17 of these were built in total.
In flight the Mil Mi-10 helicopter proved slightly unstable when unloaded. In addition the tv camera used to monitor the external loads proved to be inadequate. The later Mi-10K models were fitted with an external gondola complete with flight controls for flying the helicopter with a better view of the cargo for take off and landing.
Although the Russian air force has ceased using the aircraft, some small Russian domestic carriers still use the Mil Mi-10 helicopter for commercial use.
For some additional images of the Mil Mi-10 English Russia has some great photos of one held at the museum of Monino near Moscow.