In the mid-1950s, helicopter transportation became extremely popular in the USSR, as it turned out to be very convenient. Thanks to the advent of helicopters, it became possible to quickly travel to the most inaccessible regions of the country. As a result, the number and volume of transportation constantly increased, and at the same time, the need for more capacious machines grew. By 1958, the largest passenger helicopter was the 16-seat Mi-4, and less than 10 years later, the Mi-8 was operating on passenger routes, which could accommodate twice as many passengers. However, by the early 1960s, even this was no longer enough. Therefore, Aeroflot management asked the Mil Design Bureau-329 for an even larger passenger machine, which it was decided to build on the basis of the Mi-6 helicopter
The Mi-6P remains the largest passenger helicopter ever built. Photo source: twz.com
Mi-6 — the legendary Soviet helicopter
Work on the Mi-6 helicopter was initiated by the Resolution of the Council of Ministers on the development of a heavy transport helicopter dated June 1, 1954. According to this document, the helicopter was to transport cargo weighing up to 6 tons at normal takeoff weight, up to 8 tons at overload weight and up to 11.5 tons during a shortened flight.
OKB-329, which is also known for its other helicopters, such as the Mi-28, began creating the Mi-6 in three versions at once – transport, troop and medical. Moreover, the main purpose of the helicopter was to land troops. After only 3 years, the first finished model was ready for flight tests, which first took place in June 1957. In 1960, the first military Mi-6 helicopters were created for trial operation, and two years later the first civilian helicopter entered testing.
Initially, the Mi-6 was developed as a military helicopter. Photo source: techinsider.ru
It should be said that the helicopter turned out to be very large – its length was 35 meters, and the height when parked was 9.15 meters. Therefore, to this day, it remains one of the largest helicopters in the world. In addition, the machine turned out to be extremely progressive for its time. Mi-6 was able to set several world records. In particular, it overcame the speed of 320 km/h, which at that time was considered unattainable for helicopters. For this achievement, the OKB even received the Igor Sikorsky Prize of the American Helicopter Society. By the way, this speed is still considered very high for helicopters. For example, Boeing is working on creating the fastest helicopter, which will accelerate to 333 km/h.
The largest passenger helicopter in the world
In 1963, Aeroflot's management succeeded in getting OKB-329 to include a passenger version of the helicopter in the development plan. By this time, military and civilian Mi-6 helicopters had been in operation for several years. The first rotary-wing airliner, the Mi-6P, was built on the basis of a cargo helicopter and was introduced in 1965. In fact, it was originally a cargo helicopter converted into a passenger helicopter.
The first passenger helicopter Mi-6 was introduced in 1965. Photo source: twz.com
The capacious cargo compartment, 12 meters long and 2.5 meters wide, included 80 comfortable seats, 5 in a row. As a result, the helicopter was almost as large as the Russian Sukhoi SuperJet jet airliner. Along the sides of the passengers were luggage racks, like in an airplane cabin. Personal lamps and fans were provided above the passenger seats.
The cabin of the Mi-6 passenger helicopter. Photo source: twz.com
The Mi-6P cabin had a ceiling height of 2.65 meters, which is significantly higher than that of aircraft of that time. In addition, it had larger windows, providing good visibility. In this regard, the helicopter was even more comfortable than aircraft. There was a toilet in the tail section of the fuselage. An additional level of comfort was provided by heat and sound insulation of the cabin.
USSR-58647 at the Paris Air Show. Photo source: twz.com
Two years later, the first Mi-6P was built from scratch, receiving the tail number USSR-58647. It also became the last passenger Mi-6, which went down in history, but remained unsurpassed.
Why the Mi-6P was not mass-produced
In 1967, the USSR-58647 was presented at the Le Bourget Air Show in Paris, where it was reportedly very well received by the public. This is not surprising, since nothing like it existed in the West at the time. However, for some reason, it was decided to abandon the serial passenger helicopter. What exactly went wrong remains a mystery – no source reports this information.
The helicopter with the on-board number USSR-58647 was transferred to the USSR Ministry of Defense for operation. Photo source: twz.com
The helicopter with the on-board number USSR-58647 was not used for its intended purpose, and in 1970 it was transferred to the balance sheet of the USSR Ministry of Defense. But despite the fact that the project was effectively curtailed, the need for a large passenger helicopter did not disappear. Therefore, in the 80s, a large passenger helicopter Mi-26P was created based on the next-generation machine.
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But the Mi-26P is inferior in terms of capacity to its predecessor – the cabin accommodates only 63 passengers. True, in the 80s, a project for 70 seats was also developed, but it was not implemented. Nevertheless, the Mi-26P currently remains the largest passenger helicopter in operation in the world.