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Mil GM-1 / Mi-1 / Mi-3
PZL Swidnik SM-1
PZL Swidnik SM-2

Mikhail Mil was a contemporary of Nikolai Kamov at the TsAGI (Central Aero and Hydrodynamic Institute) during the 1930s, was given charge of his own design bureau in 1947 and became responsible for the first Soviet helicopter to go into quantity production. The GM-1 / Mi-1.

Designed to meet a requirement for a three-seat communications machine which was issued in late 1947 and originally designated GM-1 (Gelikopter Mil, or Mil helicopter), the Mi-1 first of three prototypes was completed and flown in September 1948 piloted by M.K.Baikalov (ex-Bratukhin).

 

 

The Mi-1 was a compact machine with a fully-enclosed metal-skinned fuselage. Fuselage light alloy, except for welded steel tube basis of mid-section housing engine with crankshaft horizontal and cooling fan, driving through angle box to transmission with centrifugal clutch and rotor brake. Four-seat cabin with left/right hinged doors. Fuel in welded aluminium tank 240 lit behind engine and, from about 40th production, provision for external supplementary tank of 160 lit on left side. Monocoque tail boom and pylon for tail rotor with three wooden blades. A 2.5m shaft runs from the gearbox to the tail rotor. Fixed nosewheel-type landing gear with brakes, plus long rear skid to protect tail rotor. Three-blade main rotor, blades based on A-15 and related autogyros, mixed steel/ply/fabric NACA-230 profile, fully articulated hub with friction dampers, normal speed 232 rpm. The powerplant was an Ivcheriko AI-26V radial engine driving a three-bladed rotor and producing 575 hp at takeoff. Like Soviet equipment during World War II, the Mi-1 is designed to operate at very low temperatures and has anti-freeze sprays for not only the rotors but also the windscreen.

Both the first two GM-1 were lost, the second killing Baikalov after a weld failure in the tail-rotor bearing. Project taken over by Mark Gallai and V.V.Vinitskii, followed in summer 1949 by NII testing by G.A.Tinyakov and S.G.Brovtsyev. The Mi-1 reached a height of 6800m and speed of 190.5km/h. Yak-100 delayed so production was authorized as Mi-1 and delivery of the production models began in 1951. The Mi-1 made its public debut when eight took part at the Tushino Air Display in 1951, by which time it was already in production and service with the Soviet armed forces. The four-seat Mi-1 was ordered into production in September 1949. NATO code name ‘Hare’.

 

 

Subsequent production of the Mi-1, both in the Soviet Union and in Poland, has been extensive. Polish production began with the standard Mi-1 late in 1955, this being built at the WSK works at Swidnik under the designation SM-1 with a licence-built version of the AI-26V engine.

Once military requirements had been met by a production run of several hundred, the Mi-1 was also widely adopted for a great variety of civil tasks, such as air ambulance duties, fish-spotting or whaling, ice patrol in polar regions, highway patrol and for carrying mail.

 

 

From about the 40th, the Mi-1M was produced with a 0.32m adjustable stabilizer (tailplane).

From 1957 new blades with extruded steel-tube spar. By this time the basic model was the Mi-1T, which carries only 2 passengers plus radio and fluid de-icing, the 1950 Mi-1MU which is a dual-control trainer and the 1956 Mi-1NKh (Narodnoye Khozyaistvo), a utility model for such duties as freight and mail carriage, ambulance and agricultural operations. In an agricultural role it can be fitted with spraying bars and two 250-litre tanks, carrying 400kg at the sides of the fuselage.

In 1961, the Mi-1 Moskvich passenger version was developed for Aeroflot, with an all-metal rotor of almost untapered plan, hydraulic controls, better cabin soundproofing and night flying or all-weather instrumentation. The name was dropped and the improvements were mostly standardized.

Mil produced an ambulance version, the patients carried on stretchers in streamlined pods on either side of the fuselage. Pipes connected the pods to the fuselage to allow the temperature to be controlled.

The final production run was the Mi-1T, a three-seater with different operational equipment.

In 1956, a prototype (identified in the West as Mi-3) was also evaluated. This had a four-blade rotor, wider cabin, and various other external modifications, such as two lateral stretcher panniers, but it did not enter production.

Several of the Mi-1's supplied to foreign air forces were Polish-built, and subsequent versions included the SM-1W (pilot and 3 passengers), SM-1WS (2-stretcher ambulance), SM-1WZ (agricultural) and SM-1WSZ (dual-control trainer). Production of the Mi-1/SM-1 is thought to have been phased out around 1963 in favour of the later turbine-powered developments.

 

The PZL Swidnik SM-2, Polish development of the basic design was flown late in 1959. This has a longer nose, enlarging the cabin to accommodate 4 passengers in addition to the pilot. In the ambulance role, the SM-2 can take a third stretcher inside the cabin in addition to the two carried on external panniers. Production of the SM-2 was initiated in 1961 to fulfil both military and civil orders.

 

 

Other variants include the Mi-1MRK reconnaissance and fire adjusting helicopter of 1960, Mi-1MG (Mi-1G) helicopter with float-type gear, SM-1/300 experimental helicopter with additional wing of 1971, and Mi-1M experimental helicopter with additional servo-tab of 1959.

The first armed Mi-1MU helicopter had TRS-132 rocket pods in 1958, and 4 Falanga anti-tank guided missiles in 1961.

In addition to those built for the Soviet armed forces, military Mi-1's have also been supplied to the DOSAAF and the air forces of Albania, Afghanistan, Cuba, Czechoslovakia, Finland, Iraq, Poland, Syria, the United Arab Republic and the Yemen. A wide range of duties has included those of observation, liaison, rescue, ambulance and training.

Production of the Mi-1 ended in 1961 in the Soviet Union and in 1965 in Poland.

 

 

Gallery

 

Mi-1
Engine: 1 x Rybinsk AI-26V piston, 432kW
Main rotor diameter: 14.35m
Length without rotors: 12.05m
Height: 3.28m
Max take-off weight: 2550kg
Empty weight: 1900kg
Max speed: 190km/h
Cruising speed: 140km/h
Service ceiling: 4000m
Hovering ceiling: 2000m
Range: 360km
Payload: 500kg
Crew: 1
Passengers: 2

Mil Mi 1
Engine: Ivchenko AL-25 V, 424 hp
Length: 39.698 ft / 12.1 m
Height: 10.827 ft / 3.3 m
Rotor diameter: 46.916 ft / 14.3 m
Max take off weight: 5622.8 lb / 2550.0 kg
Weight empty: 3880.8 lb / 1760.0 kg
Max. speed: 111 kts / 205 km/h
Cruising speed: 76 kts / 140 km/h
Initial climb rate: 1377.95 ft/min / 7.00 m/s
Service ceiling: 18045 ft / 5500 m
Range: 319 nm / 590 km
Crew: 1+2