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Mi-1 HARE

The Mi-1 Hare entered series production in 1951. The Mi-1 remained in production until 1964. Poland built a version designated SM-1. The three-blade main rotor is mounted on a high hump on top of the fuselage midsection. The single radial piston engine is mounted beneath a hump on top of cabin. The fuselage, which is tadpole-shaped when viewed from bottom, features a rounded nose and rear sections with a stepped, glassed-in cockpit and a long, thin, tapered tail boom. The tail consists of a swept-back fin with a rotor on the right top. Small flats are equally tapered and mounted directly in front of the fin.

The first helicopter created by the Mil Design Bureau was initially designated GM-1 (Ghelikopter Mil'a-1, Mil's helicopter No. 1). While developing a wholly original design, the Soviet engineers strove to take advantage of the experience of autogyro and helicopter construction both at home and abroad, but they had to take into account the real capabilities of the Soviet aircraft industry. For example, the only Soviet engine suitable for helicopters was the AI-26GR seven-cylinder air-cooled radial designed by Aleksandr G. Ivchenko (OKB-478), delivering 500 to 580 hp. It was around this engine that Mil's first helicopter was designed (the same was the case with helicopters which were being developed at the time in Ivan P. Bratukhin's and Aleksandr S. Yakovlev's Design Bureaux).

The GM-1 was designed as a liaison helicopter intended to carry one pilot and two passengers. The helicopter had a classic single-rotor layout with three-bladed main and tail rotors.

Main rotor diameter and tail rotor diameter were 14.36 m and 2.5 m accordingly. The main rotor blades were tapered from root to tip and were fully articulated. The hub featured offset flapping and drag hinges. Friction dampers were used to damp oscillations of the blade in the rotation plane. The main rotor blades were of mixed construction, with a steel spar consisting of three tubes with telescopic joints, wooden ribs and stringers, and fabric covering. In order to rule out the loss of the blades' stability, M. L. Mil suggested that a special universal joint be incorporated into the actuating shaft governing the blades' pitch. The trapezoidal wooden blades of the tail rotor were attached to the hub by means of flapping and feathering hinges.

The forward fuselage incorporated a glazed cabin for the pilot and passengers. A two-seat bench was placed behind the pilot's seat. Behind the cabin was the engine compartment with the AI-26GR engine, two-stage main gearbox, main rotor brake, combined coupling and freewheeling clutch and cooling fan. The main fuel tank holding 290 litres (63.8 Imp gal) was placed behind the engine. The helicopter's range could be increased by installing a supplementary external strap-on fuel tank. Attached to the rear fuselage was the tailboom of semi-monocoque construction housing the transmission shaft and the intermediate gearbox. The tailboom ended in an upward-angled monocoque pylon carrying the tail gearbox and the anti-torque rotor. The control system featured cables and inertia dampers. The helicopter's wheel undercarriage comprised main units with oleo legs and bracing struts, a nose unit with a castoring wheel and a skid under the tail boom.

OKB-4 had no production facility, and the first three prototypes were built at the aircraft plant No. 473 in Kiev (at present the Aviant factory). The first prototype was completed in August 1948. Its first tethered tests took place in Kiev, then the helicopter was moved to Zakharkovo airfield where on 20th September the first free hover, with tethers still attached, was performed. As early as 30th September the GM-1 made a flight with a forward speed of 50 to 100 km/h (31.1 to 62.1 mph). Factory tests were conducted by test pilots M. K. Baikalov, M. L. Gallai and V. V. Vinitskiy, while G. V. Remezov was chief project engineer. The final assembly and refinement of the helicopters after their delivery from Kiev was in the charge of M. N. Pivovarov. Sadly, the first two prototypes were lost in the course of the factory tests. The first aircraft crashed on 24th November 1948 when test pilot M. K. Baikalov was performing a flight to establish the machine's service ceiling. The lubricant in the control system's mechanisms froze, rendering the helicopter uncontrollable and leaving Baikalov no choice but to bail out. The other prototype was lost on 7th March 1949. The cause was traced to the failure of the pylon shaft of the tail boom transmission. Baikalov was killed in the crash. At the end of August 1949 the third prototype was presented for State acceptance trials which were passed successfully. In 1950 The GM-1's ability to make emergency landings in autorotation mode was tested. In the course of building and testing the helicopter its designers succeeded in solving a number of complicated problems connected with ensuring the fatigue strength of the primary structure members subjected to high variable stresses.

On 21st February 1950 the Council of Ministers of the USSR issued a directive calling for the construction of a test batch of 15 GM-1 helicopters, now designated Mi-1, at Plant No. 3 in Moscow. Unfortunately, State leaders and high military officials underestimated the role of helicopters in the Armed Forces and in the national economy. As a result, the introduction of the Mil Design Bureau's first progeny into a large-scale production was constantly delayed. The situation changed only after the helicopter was shown to Stalin at his country-house near Sochi in the summer of 1951, and after reports had come in about the effective use of helicopters by Americans in Korea. This was followed in October by the adoption of a Government resolution (see Mi-4 chapter) which called for the design of new transport and troop-carrying helicopters, and the Mi-1 was put into production at several aircraft plants. In the time frame between 1952 and 1953 a small batch (30 machines) was built at Plant No. 387 in Kazan' (at present the Kazan' Helicopter Plant). This was followed by large-scale production of the Mi-1 which was started in 1954 at Plant No. 47 (at present the Strela enterprise) in Orenburg; 597 machines were built there between 1954 and 1958. Three years later, Plant No. 168 (at present Rostvertol Joint Stock Company) in Rostov-on-Don joined in the production of the Mi-1; it produced 370 machines between 1956 and 1960. The Mi-1's rivals - the Yakovlev Yak-100 and Bratukhin B-11 helicopters - did not enter series production.

The first production Mi-1s were delivered to an independent training and communications squadron in Serpukhov near Moscow, where civil aviation pilots were converted to helicopter took conversion training on the helicopter. Originally, the intention was to put the Mi-1 on the strength of Transport Aviation regiments. Instead, production helicopters were assigned to the aviation elements (flights) of mechanised infantry divisions; which these flights were later upgraded to squadron status.

The Mi-1 became the first rotary-wing training machine to be delivered to military schools and DOSAAF air clubs. (DOSAAF = Dobrovol'noye obschchestvo sodeystviya armii, aviahtsii i flotu - the Voluntary Society for Supporting the Army, Air Force and Navy; now called ROSTO - the Russian Defence Sports & Technical Society.) It was on this helicopter that the Soviet Union's national team took part and gained victories in international competitions. Thanks to its high flying performance the Mi-1 established 27 world records. 'In its category the Mi-1 helicopter is on a par with any Western helicopter as far as performance is concerned' - this was the opinion voiced by foreign pilots who had flown this Russian helicopter. The Mi-1 was operated in military and civil roles not only in the Soviet Union. Besides the Warsaw Pact countries, it was supplied to Afghanistan, Austria, Brazil, Egypt, Finland, Iraq, Indonesia, China, Cuba, Lesotho, Mongolia, Nicaragua, North Korea and even Australia. In 1955 the process began of transferring Mi-1 production to Poland where it was built in series under the designation SM-1 (smiglowiec Mila - Mil Helicopter, Type 1) at the WSK Swidnik plant between 1957 and 1965 (WSK = Wytwrnia Sprzetu Komunikacyjnego, Communications Machinery Plant). Thus, the first Mil helicopter laid the foundation of the Polish helicopter construction.



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