Mil Mi-6 / M-22
Developed to meet both VVS and Aeroflot requirements, the Mi-6 was also the first turbine-powered helicopter to enter production in the USSR. First flown in June 1957 by Rafail Kaprelian, five aircraft were involved in the development programme, which was completed very quickly for such a revolutionary aircraft, with production beginning in 1960. The first flown made its maiden flight originally without the shoulder-mounted stub wings which are sometimes fitted to production Mi-6's. On October 30 1957 an Mi-6 lifted 12,000kg to 2432m.
Of conventional helicopter configuration, the Mi-6 introduced two readily-detachable short-span shoulder wings which offload the rotor by some 20 per cent in cruising flight; for heavy-lift operations the stub wings are removed to give greater payload capability. For normal operations they can be fixed at either of two angles of incidence. Development by Mikhail L Mil's design bureau at Zaporozhye of the dynamic system (rotors and shatting) of the Mi-6 was matched by Soloviev's development of the R-7 gearbox, which weighs 7,054 lb (much more than the pair of engines).
When the Mi-6 first appeared, it was claimed to have a maximum passenger capacity of 120, with normal capacity for 70 to 80, each with 20kg of baggage. Such an airliner was built in 1967, but failed to proceed beyond the prototype stage. The standard capacity of 65 passengers in the convertible model is provided with tip-up seats along the cabin walls and with removable seats on the floor.
The prototypes were powered by two 4635shp Soloviev TV-25VM turboshafts, but production models have the 5500shp Soloviev D-25V developed models. Also fitted is a 100hp AI-8 auxiliary power unit for starting the engines in the absence of any external power source. The developed engines, which keep their rating at altitudes up to 3000m and so make possible operations in 'hot and high' conditions, also allowed some notable records, the most impressive being an altitude of 2840m with a 25,105kg payload on May 28, 1965.
The fuselage construction is a metal semi-monocoque pod-and-boom design, with large hydraulically operated clamshell doors at the rear of the pod. These doors, which can be removed to allow the carriage of outsize cargoes, cover an opening measuring 2.65m by 2.7m and leading into a hold with a volume of 62cu.m, measuring 12m by 2.65m by 2.5m. Freight is handled with the aid of an 800kg winch. As an alternative to internal freight, a load of 9000kg can be carried in a sling suspended from a cable on the aircraft's centre of gravity, dropped through a hatch in the floor. The Mi-6 also has an electric winch for use when hovering which has a capacity of 500kg.
Five-blade main rotor and four-blade tail rotor. Main rotor blades each have tapered steel tube spar, to which are bonded built-up metal aerofoil sections. Conventional transmission. Main reduction gearbox drives tail rotor, fan AC generators and hydraulic pumps. Intermediate reduction gearbox fitted with special fan. Two small cantilever removable shoulder wings mounted above main landing gear struts, offload rotor by providing some 20% of total lift in cruising flight. The wings are removed in the fire-fighting variant, which can carry 12,000kg of water. Tail rotor support acts as vertical stabiliser.
The blades have coincident flapping and drag hinges and fixed tabs. Main rotor shaft inclined forward at 5 degrees to vertical. Control via large welded swashplate. Hydraulically actuated powered controls. Main rotor collective-pitch control interlocked with throttle controls. Variable incidence horizontal stabiliser near end of tailboom for trim purposes.
Power is from two 4,101kW Soloviev D-25V (TV-2BM) turboshafts, mounted side by side above cabin, forward of main rotor shaft. There are 11 internal fuel tanks, with total capacity of 6,315kg, and two external tanks, on each side of cabin, with total capacity of 3,490kg. Provision for two additional ferry tanks inside cabin, with total capacity of 3,490kg.
Crew of five, consisting of two pilots, navigator, flight engineer and radio operator. Four jettisonable doors and overhead hatch on flight deck. Electrothermal anti-icing system for glazing of flight deck and navigator's compartment. Equipped normally for cargo operation, with easily removable tip-up seats along sidewalls. When these seats are supplemented by additional seats installed in centre of cabin, 65 to 90 passengers can be carried, with cargo or baggage in the aisles. Normal military seating is for 70 combat equipped troops. As an air ambulance, 41 stretcher cases and two medical attendants on tip-up seats can be carried. One of the attendant's stations is provided with intercom to flight deck and provision is made for portable oxygen installations for the patients. Cabin floor is stressed for loadings of 2,000kg/sq.m, with provision for cargo tiedown rings. Rear clamshell doors and ramps are operated hydraulically. Standard equipment includes an electric winch of 800kg capacity and pulley block system. Central hatch in cabin floor for cargo sling system for bulky loads. Three jettisonable doors, fore and aft of main landing gear on port side and aft of landing gear on starboard side.
Some military Mi-6s have a 12.7 mm machine gun in the nose.
During flight trials in 1962 the Mi-6 (NATO code name Hook) established a number of impressive load-to-altitude and speed-with-payload records in 1959, most of which it bettered three years later when it set a total of eleven new FAI world records. In one of these, still unbeaten by early 1968, it lifted a payload of 20117kg. The normal load is limited to 26,450 lb (12,000 kg) internally, loaded via huge clamshell rear doors, or 19,840 lb (9000 kg) externally slung. It was also the world's first twin-turboshaft helicopter, and the first to exceed 300km/h in level flight.
An initial batch of thirty production Mi-6's was undertaken in 1958. Aeroftot was reported in 1963 to have introduced the big Mi-6. It is being used at present to carry large and unwieldy loads such as pipes for natural gas and oil installations. Test pilot I.G.Drobishevsky has taken charge of Mi-6 development for Aeroflot and is working on further applications such as the un-loading of ships and the carriage of timber. The Mi-6's in service with Aeroflot are employed mainly as freighters, in which role they have an internal capacity for 12000kg of payload. The standard passenger version seats 65 people normally, although up to 120 persons can be accommodated in a high density seating arrangement. If used as an ambulance, the Mi-6 can carry 41 stretchers and 2 medical attendants.
Major production version was the Mi-6A of which 864 were built at Rostov-on-Don (now Rostvertol) factory 1959-80, plus 50 at Moscow-Fili 1960-62.
The 'Hook' was exported to Algeria, Bulgaria, Egypt, Ethiopia, Indonesia, Iraq, Syria, Vietnam and Peru, where it was used by both the air force and army.
Flown by a crew of five, the Mi-6 has also seen extensive use with Aeroflot in civil engineering support work on projects such as bridge-laying, and as a versatile heavy transport in areas inaccessible to other vehicles. Most have the rotor unloaded in cruising flight (typically 150 mph) by a fixed wing of 50 ft 21 in span. These huge helicopters have played an active role in field exercises carrying troops (typically 68) and tactical missiles or vehicles. The under-fuselage hook can support an externally slung load of 9000kg.
Another version, developed into the Mil-10 'Harke', is optimised as a flying crane, and the Mi-6 formed basis for Mi-22 airborne command post.
Mi-6 / Hook-A
Basic transport with TV-2V. First 30 preproduction aircraft. Able to carry 70 combat-equipped troops or 65-90 civil passengers; also used in the air ambulance role, it can accommodate 41 stretcher cases and two medical attendants; can also be fitted for fire-fighting role with spraying or water bombing equipment; in the freight role the Mi-6 can carry an internal cargo payload of 12000 kg (26,455 lb)
Airline-style seating for 80 passengers; rectangular windows.
Military SAR/medevac version, first noted in 1977.
Mi-6PZh and Mi-6PZh2
Firefighters with 21,000 litres capacity in single 12,000 litre metal tank and six 1,500 litre bag tanks suspended from the fuselage.
Medevac version for 41 litters and two attendants.
Basic military transport with machine gun in nose glazing.
Convertible model with 65 folding seats.
Tanker version for ground refuelling.
Mi-6VKP (vozduzhnyi komandnyi punkt) ('Hook-B')
Command support version with dorsal 'clothesline' antenna; flat-bottom U-shape antenna under tailboom; large heat exchanger on starboard side of cabin; small cylindrical container aft of starboard rear cabin; small cylindrical container aft of starboard rear cabin door.
Mi-6VR (vodolei: Aquarius)
Rotor systems testbed used in Mi-26 development; subsequently equipped as icing spray rig.
Mi-6AYaSh / Hook-D
Airborne command post; flat-panel (reportedly SLAR), forward of external fuel tank as starboard side, many small antennas.
Mi-22 / Hook-C
Developed command support version with single large dorsal blade antenna on forward part of tailboom; small antennae under fuselage; pole antenna on starboard main landing gear of some aircraft. Also known as Mi-6AYa or Mi-6VUS in service.
Engines: 2 x D-25A turboshaft, 4045kW
Main rotor diameter: 35.0m
Length with rotors turning: 41.74m
Fuselage width: 3.2m
Max take-off weight: 42500kg
Empty weight: 27240kg
Max speed: 300km/h
Cruising speed: 250km/h
Rate of climb: 6.5m/s
Service ceiling: 4500m
Hovering ceiling: 1000m
Range with 8,000kg payload: 620km
Range with max fuel: 1450km, payload: 12000kg
Engines: 2 x Solowjew D-25W, 5425 shp
Length: 108.793 ft / 33.16 m
Height: 32.349 ft / 9.86 m
Wingspan: 114.829 ft / 35.0 m
Max take off weight: 93712.5 lb / 42500.0 kg
Weight empty: 60064.2 lb / 27240.0 kg
Max. payload weight: 26460.0 lb / 12000.0 kg
Max. speed: 162 kts / 300 km/h
Cruising speed: 135 kts / 250 km/h
Service ceiling: 14764 ft / 4500 m
Cruising altitude: 3281 ft / 1000 m
Maximum range: 783 nm / 1450 km
Range: 783 nm / 1450 km
Payload: 65 Pax / 12000kg
Engines: 2 x Soloviev D-25V single-shaft free-turbine engines driving common R-7 gearbox, 5,500 shp (4045kW) each
Main rotor diameter: 114 ft 10 in (35 m)
Overall length (rotors turning): 136 ft 11½ in (41.74 m)
Fuselage length: 108 ft 10½ in (33.18 m)
Height: 32 ft 4 in (9.86 m)
Empty weight (typical) 60,055 lb (27,240 kg)
Max loaded weight 93,700 lb (42,500 kg)
Max speed: 186 mph (300 km/h) (set 100 km circuit record at 211 36 mph, beyond flight manual limit)
Cruise speed: 250km/h / 158 mph
Service ceiling: 14,750 ft (4500 m)
Range (with half payload) 404 miles (650 km)
Range w/ aux. fuel: 1450km
Armament: normally none, or 1 x 12.7 mm calibre
Crew: Five - two pilots, flight engineer, navigator, and radio operator
Payload: 70 troop or 17,640 lb (8000 kg)