Soviet gas-turbine helicopter engine

The D-25V turboshaft gas-turbine engine was designed in 1959 on the base of the D-20P gas turbine engine core and is considered the first engine with a free turbine.

The D-25V and the R-7 gearbox were installed on large helicopters Mi-6, Mi-10 and Mi-10K, having replaced the TV-2F engines produced by the N.D. Kuznetsov Scientific and Technical Complex of Samara JSC.

The R-7 gearbox, developed by the specialists of Perm experimental design bureau for the propulsion units of the Mi-6, the Mi-10 and the Mi-10K, remained unique in the world’s gearbox industry for 25 years. The R-7 gearbox is capable of transmitting power of 11 000 hp.

For the development of propulsion unit on the base of the D-25V and the R-7, the Chief Design Engineer P.A. Soloviev, his deputy I.P. Evich and project engineer G.P. Kalashnikov were awarded with the USSR State Prize. 

The D-25VF engine (modified version of the D-25V) with the power of 6 500 hp was designed for the heavy lift helicopter ever built – the V-12 (Mi-12). The propulsion unit included 4 D-25VF engines and 2 R-12 gearboxes mounted on helicopter wings.

In 1971, the V-12 was presented in the 29th Paris Air Show (in Les Bourget). The unique rotary-wing machine created a sensation in the aviation.  

Maximum Power Output N=5 500hp

Specific Fuel Consumption С=0,296 kg/hp/hr

Gas Temperature at Turbine Inlet Т =1160K

First Wheel Diameter D=572mm

Length (without transmission) L=2737mm

Length with transmission L=5537mm

Height h=1158mm

Breadth b=1086mm

Motor Maintenance Weight М=1243kg

• At the time when the Mi-6 heavy helicopter with the takeoff gross weight of 40t was developed, the foreign analogues had maximum takeoff weight of 15t.   
• In the Soviet Union, the Mi-6 was the first to be designed to transport bulky cargo on an external sling. 
• The Mi-6 is the first Soviet helicopter powered with gas-turbine engine. 
• In total, the Mi-6 set 16 world records.
• The Mi-6 is considered to be the heaviest lift and high-speed helicopter in the world.
• In 1961, the Mi-6 set the world record of making 300 km/hr.
• It was in service during Chernobyl Nuclear Plant disaster in 1969.

Heavy helicopters Mi-6, Mi-10 and Mi-10K