During the late 1950s, the Soviet administration decided to design a helicopter with the world's largest carrying capacity. The tests of the new helicopter began ten years later. However, it just so happened that no one wanted to replicate the potential pride of Soviet engineers.
The helicopter is known as B-12, and it is unofficially known as Mi-12. Its unsuccessful story has proved that world records may at times be reductive.
During the 1960s, the production of helicopters was thriving, and military requirements were getting increasingly demanding. It was during those times when engineers designed the first intercontinental missile.
First-generation intercontinental missiles were too heavy to be transported on any means other than trains. A R-7 warhead could only be delivered by plane or train because the warhead without fuel weighed 26 tons.
Needless to say that railway transportations could be easily tracked. The USSR found that out after a story with the American reconnaissance aircraft.
After the Japanese attack on Pearl Harbor during World War II, the United States took every effort to prevent such attacks in the future.
Thus, the Lockheed U-2 appeared in 1955. The aircraft was carrying various modules, including those using ray tracing and ultra-precise lenses.
The camera of the US reconnaissance aircraft was so powerful that it was possible to count cows in a photograph of a field, taken from an altitude of 18 km.
The aircraft was flying quietly over the USSR for more than five years, until one of them was shot down and its pilot was taken hostage in 1960. However, 24 previous flights helped the Americans find out the whereabouts of Soviet military facilities, including missile ranges.
It was easy to track down those facilities on the ground with the help of conspicuous railway tracks. The USSR was convinced that it was about time to develop aerial means of transportation for missiles.
By 1963, the largest Mi-6 helicopter could lift 12 tons, but it was not good to carry a 26-ton cargo. This prompted Soviet engineers to start working on the B-12 helicopter.
At first they simply wanted to upscale the Mi-6, but it then became clear that one huge rotor could not be adapted to the laws of physics. Soviet designers decided that it would take them too long to stabilise the new technology.
They opted for a different variant, in which they took 35-meter rotors with a total capacity of 26,000 horsepower from the Mi-6 helicopter and arranged them to the sides of the hull.
The rotors moved in the opposite direction to balance each other, while the rear wing was stabilizing the swing.
We can now see this solution in the design of modern-day drones, but there were no helicopter models with this type of rotors in the past.
In terms of the size of the hull, it was larger than the Boeing 737, which can house up to 189 people.
The B-12 could carry a record 192 passengers. As for equipment, the new helicopter could fit a nuclear intercontinental missile.
In April 1965, a decree was adopted to build the first prototype of the helicopter. Two years later, the helicopter was ready, and five years after the beginning of development, the B-12 took the first flight test.
The first test turned out to be unsuccessful due to a resonance in the movement of rotor blades. Simply put, the pilot lost control of the helicopter.
The helicopter became unstable immediately after takeoff, and it started hitting the ground from a height of 10 meters. This ruined the chassis and took engineers another year to correct the mistake.
During the second test in 1969, the B-12 lifted 31 tons. A year later, the B-12 was able to hold a record 44 tons at an altitude of 2.2 km, which proved its efficiency in the task of transporting missiles weighing 25 tons.
The successful performance of the new jumbo helicopter prompted it to appear at Le Bourget international aerospace exhibition in Paris in 1971.
Being 37 meters long and 69.1 tons heavy, the B-12 was twice as large and four times heavier than largest American exhibits. The B-12 holds this record to this day.
The B-12 could develop the speed of up to 260 km/h and reach altitudes of up to 3.5 km.
Six crew members were required to pilot the B-12: the pilot, the co-pilot and the flight engineer would sit in the cockpit on the first level, and the navigator, the radio operator and the electrical engineer would help them on the second level.
Such capabilities and requirements demonstrated the military purpose of the helicopter. At the same time, the helicopter needed to be developed further. Landing and takeoff were still difficult to control, and airborne stability was far from being satisfactory too.
The exhibition in Paris became the brightest and the last triumph of the jumbo B-12 helicopter. It became redundant when new missiles were invented. The development of the helicopter was stopped 15 years after the idea to design it emerged for the first time.
There were two reasons to shelve the project:
Only two prototypes of the B-12 have been preserved to this day. The first one remains in the Museum of the Air Force of the Russian Federation near Moscow, and the second one is located in Tomilino as part of Mil and Kamov National Helicopter Center.
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