Soviet Union always loved everything big. So the decision to make the biggest helicopter with the largest carrying capacity was quite natural for the country.
Development of the V-12 project began in 1963, the serial Mi-6 helicopter became the basis for the new huge vehicle. To simplify the task the engineers just decided to double propelling plants. What they got was a “heaven monster” with four gas-turbine engines, 6497 hp each!
Full album is here he
http://www.aviationcv.com/pilot-foru...er-engineering