Mi-12 Homer (MIL)
The Mil Mi-12 (V-12) was a 120-seat heavy transport helicopter powered by four Soloviev D-25VF turbo shaft engines. Footage of the first flight was released in 1968. This giant helicopter had fixed wings and was lifted by two Mi-6 rotors mounted at the ends of outrigger wings. Two [or three??] prototypes of MI 12 were built, but the helicopter never entered production.
Although it was constructed only two copies of Mil Mi-12 (V-12) experimental helicopter, the famous giant machine is the biggest helicopter in the world. Rotor, transmission and engine were taken from the MI-6, but are duplicated and located at the ends of the still backed truss brace consoles wing. The use of two rotating in opposite directions rotor ruled out the need for a tail propeller, and the plumage was traditional - with two additional washers at the end inhibitor. Four turbovalnyh engine Soloviev D-25VF had a total capacity of the shaft 19388 KW (26000 HP), which enabled a helicopter-12, first took off July 10, 1968., Set in February 1969. a series of records that will be presented for approval were first received in the West reported on the existence of the giant helicopter. He received the NATO code of"Homer" ( "Homer"). Later, on 6 August 1969., B-12 raised the payload 40204.5 kg (88,636 pounds) to an altitude of 2255 meters (7398 feet), setting a record which has so far not exceeded. The first test copy was destroyed during landing (with no deaths) in 1969. The second Mi-12 participated in the demonstration flights.
The Mil Mi-12, known as V-12 in the Soviet Union, and by the NATO reporting name Homer, is so far the only helicopter produced by the Mil bureau to depart from the single main rotor plus tail rotor formula. The tandem rotor (or twin-rotor) configuration is used mainly with large helicopters. Because of the opposite rotation of the rotors, the torque of each single rotor is neutralized. The construction of the control system is much more complicated compared to a helicopter with a tail rotor. The arrangement of two rotors side by side was never very popular. This design was used for the largest helicopter ever built - the Mil Mi-12.
The giant V-12 was a four-engine troop-carrier helicopter of twin-screw transverse layout. Power plants from Mi-6 were fastened to the ends of the truss consoles. The diameter of the finished rotors proved to be insufficient for this helicopter that it required boosting initial power plants. Two main rotors contra-rotating, slightly mesh into one another, turning A122 rpm, are mounted each at the end of a wing. The left rotor turns in the direction clockwise, the right rotor in the opposite direction to clockwise, seen from below. The metal blade entirely, each weighing 840 kg for 17 m in length are composed of metal spar on a tight tubular diameter, but whose thick walls are decreasing. The hubs are a classic cyclical plateau consists of two welded half-shells. The two rotors are linked by two shafts rigid, leading large diameter, a central gear box with a take-off (drive hydraulic pumps). This transmission is calculated so as to transmit the power necessary with two turbines arrested on the same side.
Four Soloviev D-25VF turboshaft engines developing 4 850 kW each are mounted in pairs. Each pair is coupled to cause a rotor, but is also interconnected with each other to ensure relief lift of the aircraft. The lower cowl under each pair may fall to 1.80 m with a crank, to form a working platform where three men maintain engines and the rotor head. The rollovers for later fell back down to the same purpose. For the V-12 the OKB P.A.Solovyev created the special modification of the production engine D-25f with a power of 6500 hp. In the center section the intermediate gearbox, which ensured the fracture of power shaft, was established. Power shaft synchronized the rotation of had three-meter overlap rotors and delivered power from one reducer to another with the roll control and in the case of failure of one or even two engines from one side. Fuel was placed in the wing and external external fuel tanks.
The wings with a contraction of less than one had a small dihedral angle for an improvement in the piloting helicopter characteristics. The high rise wing of inverted trapezoidal shape in plan view, the string is the smallest side emplanture at corner and many high profile guy, is metal construction. Flap-edges equip the prototype but would no longer appear on the aircraft. The fuselage, construction classic semi-monocoque, all-metal, has in the back of a rack and two doors opening in shell laterally. The ramp is equipped with two large bumper side by side to adjust the height from the ground.
The fuselage of the V-12 was executed in the form semi-monocoque and resembled inside, according to descriptive expression of one of the foreign specialists, the gigantic Gothic cathedral. Two-story flight deck occupied its forward section. The cockpit, very classic, is located halfway up the front of the fuselage. It is occupied by a pilot on the left, a co-pilot side by side, right, a flight engineer behind the driver and an electrician behind the co-pilot. On the upper deck, above the cockpit are the positions of the browser and the radio operator. The crew would only fan blades rubber for air conditioning. A large cargo freighter, without any obstruction following posts before. The ceiling has rails on which the wings, from one end to another of the fuselage, a crane with 10 tons capacity. Fifty people can be carried on canvas folding seats against the side walls. Access to the main cabin is done by two side doors left and right, the crew with sliding doors front right and left. The cargo and vehicles entering the ventral rear hatch. In the aft fuselage section the power ladder and the lateral folds, which during deployment formed aperture for the entrance of self-propelled technology and loading of different loads with the aid of the powerful electric hoists and the telphers, were found. Center fuselage occupied large cargo hold by the size of 28,15 X of 4,4 X of 4,4 meters. In it could be placed 196 soldiers or 158 injured.
The electrical system has a capacity of 480 kW. An auxiliary power Ivchenko AI-8V allows for his power to make the aircraft independent of its parking place. A ground mapping radar is mounted under a radome at the bottom of the front fuselage. The aircraft is equipped with an automatic stabilization and a command system that continually "fail-safe", but it can land manually.
Non-retractable tricycle with twin wheels at each leg of the train. The main gear is fixed, through numerous shrouds, the wing and fuselage. Two small diabolos are set at the lower rear fuselage to avoid shocks to the nose landing position. Tires main wheel x 1 750 730 mm 730 mm ; ceux de roues avant 1 200 X ; Those front wheels 1 200 X 450 mm 450 mm.
The fuel would seem to be stored in the wing or under the cabin floor. Two reservoirs cylinder fitted latÚralement the device seen in 1971 in the West. They could only be intended as conveying over long distances.
From behind under the fuselage was arranged "aircraft" tail assembly with the elevators and direction and two vertical washers. Rudder was intended for increasing the effectiveness in the azimuth guidance. The elevator control was accomplished synchronously with the collective pitch control of rotors. The schematic layout of control V-12 was the standard for the helicopters transverse layout: the amount of lift was regulated by a simultaneous change in the collective pitch; the differential collective pitch control ensured roll control; a change in the longitudinal balance and amount of propulsive force was accomplished by a change in cyclic pitch of both rotors with the aid of the automatic pitch-control mechanisms; a differential change in the cyclic pitch ensured azimuth guidance.
The system of control V-12 was designed taking into account the large extent of installation, possible of the structural distortions, large mass it is sufficient large frictional forces of the elements of installation. System was two-stage and included basic and intermediate hydraulic amplifiers, automatic devices, which ensure the permissible loads on the control elements and the effective synchronization of their deviation. The sustainment of the intermediate hydraulic amplifiers of the rudders and height was achieved from the hydraulic system, which is located in the section of the intermediate gearbox, while that of basic hydraulic amplifiers - from the hydraulic systems, located in the left and right pods. All three systems were completely autonomous, each of three systems, in turn, consisted of main and duplicating systems.
The helicopter V-12's landing gear was tripod. Front support with the swivel dual wheels was located under the flight deck, basic supports with the dual wheels - under the left and right farms. All landing gear struts had pneumo-oil shock absorbers. From behind fuselage it was arranged the additional tail struts, which make it possible to load heavy technology into the cargo compartment.
The new helicopter was equipped with the contemporary flight systems, which make it possible to carry out flights in the adverse weather conditions. Substantial simplified piloting of the V-12 was done with a four-channel autopilot and system of the automatic maintenance of the master frequency of the rotation of rotor.
In spite of its unique characteristics, the V-12 did not enter into the series production and the operation. There were several reasons. The main thing consisted in the fact that the task, for the fulfillment by which it was created by V-12, guarantee of a mobile basing of strategic ballistic missiles - lost urgency toward the end the 60's. Customer changed the concept of the basing of rockets. Some types of missile complexes, under which was developed V-12, proved to be unsuccessful and they were taken from the armament (for the same reason the planned to the production large series An-22 it was sharply reduced). Other analogous forms of military loads did not require so sharply this expensive means of delivery by helicopter. Furthermore, the Saratov plant, which was being prepared for the production V-12, for the moment of making a decision about the starting of this giant into a series proved to be the tightly loaded production of another form of production. And to crown it all, in the prevailing circumstances of OKB it proved to be not interested in the introduction V-12, since this could prevent the begining of development of the new promising heavy helicopter of the third generation Mi-26, inferior to the twin-screw giant on the load capacity, but considerably exceeding it according to the technical and economic indices.
The pride of MVZ im. M.L.Mil and the entire domestic helicopter construction - the V-12 remained unsurpassed in two copies, but the experience of designing and tests of these exceptional machines was not in vain. Development V-12 made it possible to create the complex method of analysis and selection of the optimum parameters of helicopter taking into account the phenomena of dynamic structural instability, to confirm the advantages of the helicopters of transverse layout, to prove the expediency of using the method "of the doubling" of power plants for an increase in the load capacity of rotating wing aircraft.
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