Tag Archives: Soloviev D-25VF

6 August 1969

One of the two Mil Design Bureau Mi-12 heavy lift helicopter prototypes, 1971. (Groningen Airport-Eelde)

6 August 1969: The largest helicopter ever built, the four-engine, transverse-tandem rotor Mil Design Bureau Mi-12, registration CCCP-21142, lifted a payload of 40,204.5 kilograms (88,635.7 pounds) to an altitude 2,255 meters (7,398 feet), setting three Fédération Aéronautique Internationale (FAI) world records for payload to altitude. These records have never been broken by any other helicopter.

The helicopter was flown by Vasily Kolochenko, with L.V. Vlassov, V.V. Juravlev, V.P. Bartchenkov, S.G. Ribalko, and A.I. Krutchkov.

FAI Record File Num [Direct Link]
Status: ratified – current record
Region: World
Class: E (Rotorcraft)
Sub-Class: E-1 (Helicopters)
Category: General
Group: 2 : turbine
Type of record: Altitude with 35 000 kg payload
Performance: 2 255 m
Date: 1969-08-06
Course/Location: Podmoskovnoe (USSR)
Claimant Vasily Kolochenko (URS)
Crew L.V. VLASSOV, V.V. JURAVLEV, V.P. BARTCHENKOV, S.G. RIBALKO, A.I. KRUTCHKOV
Rotorcraft: MIL M-12 (V-12)
Engines: 4 Soloviev D-25 VF

FAI Record File Num [Direct Link]
Status: ratified – current record
Region: World
Class: E (Rotorcraft)
Sub-Class: E-1 (Helicopters)
Category: General
Group: 2 : turbine
Type of record: Altitude with 40 000 kg payload
Performance: 2 255 m
Date: 1969-08-06
Course/Location: Podmoskovnoe (USSR)
Claimant Vasily Kolochenko (URS)
Crew L.V. VLASSOV, V.V. JURAVLEV, V.P. BARTCHENKOV, S.G. RIBALKO, A.I. KRUTCHKOV
Rotorcraft: MIL M-12 (V-12)
Engines: 4 Soloviev D-25 VF

FAI Record File Num [Direct Link]
Status: ratified – superseded since approved
Region: World
Class: E (Rotorcraft)
Sub-Class: E-1e (Helicopters: take off weight 3000 to 4500 kg)
Category: General
Group: 2 : turbine
Type of record: Greatest mass carried to height of 2 000 m
Performance: 40 204.5 kg
Date: 1969-08-06
Course/Location: Podmoskovnoe (USSR)
Claimant Vasily Kolochenko (URS)
Crew L.V. VLASSOV, V.V. JURAVLEV,V.P. BARTCHENKO,S.G. RIBALKO,A.I. KRUTCHKOV
Rotorcraft: MIL M-12 (V-12)
Engines: 4 Soloviev D-25 VF

This is the first of two Mil-12 prototypes built by the Mil Design Bureau. (Both had the same registration number: 21142.) They were intended to transport intercontinental ballistic missiles and load them directly into underground silos where there were no existing roads. The aircraft was operated by a six-man crew.

The Mi-12 has a length of 37.00 meters (121 feet, 4.69 inches) and rotor span of 67 meters (219 feet, 9.79 inches). Its height is 12.50 meters (41 feet, 0.13 inches). The helicopter has an empty weight of 69,100 kilograms (152,339 pounds) and maximum takeoff weight of 105,000 kilograms (231,485 pounds).

The Mi-12 uses two main rotor, transmission and twin engine systems from the single rotor Mil Mi-6 helicopter. Each rotor had a diameter of 35.00 meters (114 feet, 9.95 inches). The total disc area is 1,924 square meters (20,710 square feet). The left rotor turns counter-clockwise, as seen from above. The right rotor turns clockwise. (The advancing blades of both rotors are inboard.) With counter-rotating main rotors, the torque created by each rotor system is cancelled out, eliminating the need for a tail, or anti-torque, rotor. This makes the total power produced available for lift.

Three-view illustration of Mil Mi-12. (Aviastar)

The Mil Mi-12 is powered by four Soloviev Design Bureau D-25VF turboshaft engines. The D-25VF has a nine-stage axial-flow compressor section and a three-stage turbine. Each engine is 2.737 meters (8 feet, 11.76 inches) long, 0.508 meters (1 foot, 8.00 inches) in diameter, and weighs 1,200 kilograms (2,646 pounds). In the Mi-12, two engines are coupled to a single gear box, and mounted at the ends of the wings. The D-25VF has a maximum power rating of 4,847 kilowatts (6,500 shaft horsepower). The four engines, combined, produce 19,388 kilowatts (26,000 horsepower).

The helicopter’s internal cargo bay is 4.40 meters (14 feet, 5.23 inches) wide, 4.40 meters (14 feet, 5.23 inches) high, and 28.15 meters (92 feet, 4.27 inches) long. It can carry 40,000 kilograms (88,185 pounds) of cargo internally, or 5,500 kilograms (12,125 pounds) as a sling load.

The Mi-12 has a maximum range of 500 kilometers (311 statute miles) with a 35,400 kilogram (78,044 pounds) payload. The maximum speed is 260 kilometers per hour (162 statute miles per hour/140 knots) and the service ceiling is 3,500 meters (11,483 feet).

The Mi-12 was not put into series production. The record-setting first prototype is at the Mikhail Leontyevich Mil helicopter factory at Panki-Tomilino, near Moscow.

World Record Mil Mi-12 at Tomolino.
World Record holding Mil Mi-12 at Tomolino. (Yuriy Lapitskyi)

© 2023, Bryan R. Swopes