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D-25V

D-25V THE WORLD’S FIRST GAS TURBINE ENGINE FOR HELICOPTERS

Gas turbine engine D-25V was developed in 1959 for heavy transport helicopters Mi-6, Mi-10, Mi-10K created in Mikhail Mil’s design bureau. The engine was based on the D-20P gas turbine engine core. For developing the D-25V-based helicopter propulsion unit, P.A. Solovyov, his deputy I.P. Evich and project engineer G.P. Kalashnikov were awarded with the USSR State Prize.

The D-25V engine with 5 500 horsepower output, had a high gas dynamic resistance to environment factors. The maximum power remained unchanged at heights of up to 3000 meters and at temperatures of up to +40°С during on-ground operation.

A free turbine allowed for the opportunity to establish its rpm regardless of the mode of the turbo-compressor section of the engine. This feature provides for a number of design and operational advantages including:

getting the desired rpm of the helicopter rotor shaft for flight modes and heights regardless of the engine turbine-compressor section rpm;
reaching the optimal fuel consumption at different conditions of the engine operation;
providing for an easy start of the engine;
no necessity to equip the helicopter propulsion unit with a friction clutch (feed clutch).

The R-7 gearbox created by the Perm Design Bureau specialists for the propulsion units of Mi-6 and Mi-10/10K with two D-25V, had been second to none in the world’s gearbox development industry for a quarter of a century.

The D-25VF uprated version was developed in 1965 for world’s heaviest helicopter V-12 with the maximum output of 6 500 hp.

In 1970, the State Committee recommended to start the serial production of the V-12 helicopter powered by Pavel Solovyov’s engines. One year on, this unique rotary-wing machine was destined to become a “spice” of the 29th International Aviation and Space Show in Les Bourget (France).

General Characteristics
Application
Memorable Dates

SPECIFICATIONS

Full Power Conditions Н=0, М=0, ISA
Maximum Power Output, hp	5500
Pressure Ratio	5,6
Maximum Gas Temperature at Turbine Inlet, K	1240
Specific Fuel Consumption, kg/hp/hr	0,296
Corrected Air Consumption, kg/s	26,2

First Wheel Diameter, mm	572
Length, mm	2737
Weight, kg	1200

Heavy transport helicopters Mi-6, Mi-10, Mi-10K.

Heavy transport helicopter is intended for carrying cargo with the maximum weight of 12t, or 61-90 passengers. Modifications of Mi-6 (Mi-10/10K) were used as flying crane helicopters during installation and construction works.

In June of 1957 the crew of test pilot Rafail Kaprelyan were the first to bring Mi-6 to the sky. In 1959-1963 the State Tests were performed followed by introducing Mi-6 into service. Since 1963, the helicopter had been widely used in the national economy.

Transport helicopter Mi-6 is constructed in accordance with the single-rotor configuration with the lifting five-blade fullmetal control rotor and four-blade wooden control rotor. The propulsion unit consists of two turboshaft engines D-25V. In case one of the two failed, the helicopter was capable of continuing the horizontal flight. The torque at the gearbox outlet could reach 60 000 kgf·m. Other countries managed to develop such powerful gearboxes only 17 years later.

In 1959–1980, more than 850 helicopters Mi-6 and its versions were built in Rostov-on-Don, and 50 more helicopters were built in Moscow (1959-1962). The helicopter construction was constantly improved during the manufacturing process. Mi-6 were delivered to Algeria, Bulgaria, Vietnam, Egypt, Pakistan, India, Iraq, China, Indonesia, United Arab Republic, Peru, Poland, Syria, Ethiopia.

Helicopters Mi-6 participated in military operations in Afghanistan, in the rectification of the consequences of the accident at the Chernobyl Atomic Electric Power Station and others.

In 1959–1963 there were 16 world records set using Mi-6. The speed record for a closed-circle flight – 340.15 km/hr – has not been broken up to the present. In some of the record flights, the takeoff weight of the helicopter was more than 48 t. For reference: the takeoff weight of the foreign analogues still does not exceed 34 tons.

June 4, 1957

The first takeoff of the Mi-6 helicopter powered by turbofan engine D-25V, the crew headed by R.I. Kaprelyan.

The first flight: June 18, 1957.

June 14, 1960

The first flight of the Mi-10 helicopter with two Perm turbofan engines D025V, the crew headed by R. I. Kaprelyan.

September 10, 1964

The first flight of the first Mi-10 serial helicopter powered by Perm turbofan engines D-25V, the crew headed by R.I. Kaprelyan, Rostov Helicopter Plant.

January 6, 1966

The first flight of the Mi-10K flying crane helicopter with Perm turbofan engines D-25V, the crew headed by R.I. Kaprelyan

June 26, 1967

The first takeoff of giant helicopter V-12 (Mi-12) powered by Perm turbofan engines D-25VF, the crew headed by V. P. Koloshenko. The first flight: July 10, 1968.