Mi-28 HAVOC - Design
The two-place combat helicopter Mi-28 was built according to classical single-rotor design and was intended for the search and the destruction under the conditions of the opposition of the armored technology, of the live enemy target in the open and broken ground, and also the low-speed aerial targets with the visual visibility into the simple and ogranichenno the adverse weather conditions. The overall size of helicopter made it possible to transport it on the military transport aircraft Il-76 without the dismantling. Constructive solutions and layout of basic aggregates ensured the independence of conducting military operations from the areas out of the airfield during 15 days.
the Mi-28 fuselage included nose and center sections, and also tailed and keel beams. In the nose section were located two separate armored sections of the flight deck, in which they were placed from the front the armchair of navigator-radar operator, and from behind also above - armchair of pilot. For increasing the combat vitality of helicopter and survival of crew was provided for the armor protection of cab, to which entered the collection of the ceramic tiles, stuck on the body of the forward fuselage. Furthermore, shielding role performed silicate bulletproof glass. Pilot and navigator were divided by armored bulkhead. The door of navigator was found on the left side, and pilot - on by right. Doors and glass were equipped with the mechanisms of emergency discharge. With the escape of cabs under the doors were inflated the special ladders, which prevent crew from the impact about the chassis. From the front below to the nose section was attached to the stabilized platform the combined survey- aiming station COP and the frame of cannon installation. The blocks of electrical equipment and aiming-piloting- navigation complex were placed under the sex of pilot.
To the ceiling panel of center fuselage were fastened the main rotor gearbox, fan, auxiliary power plant, hydraulic unit, aggregates of conditioning system. To the right and to the left of the axis of symmetry on the ceiling panel and the cantilever elements of frames were established engines and bevel gearboxes, and also outer planes of wing. In the lower part of the fuselage was located the tank-bay liner, on upper panels of which stood the units of equipment. The arrangement of the heaviest aggregates and systems near the center of masses contributed to an increase in the maneuverability Mi-28. Rear cut off radio equipment had sufficiently capacious free volumes, which made it possible to use it as the cargo (for the transportation of airport equipment during the redislocation of the helicopter or of the evacuation of the crew of another helicopter).
Simplicity and convenience in servicing different systems and equipment of helicopter ensured numerous doors and hatchways on the sides of fuselage. The lower arrangement of tail boom excluded the possibility of touching for it by the blade of rotor with the rough maneuver. The tail end of the keel beam was executed in the form fixed control, inside which was placed the cable control run by tail rotor and by the stabilizer, which were being fastened in the upper part of the keel beam. The tail strut of chassis was located under its lower part. Wing of helicopter - be cantilevereding with four pylons, intended for the suspension of rocket, gunnery, bomb armament and extra fuel tanks. The devices for the shooting of interference cartridges were arranged on the wing tips in the fairings. In the emergency the wing could be dropped. The stabilizer control was connected with the knob of collective pitch.
The system of the passive protection of helicopter had to ensure safety of crew members with the emergency landing with a vertical velocity of up to 12 m/s. In this case the amounts of g-force were reduced to the level of those of physiologically transferred. The mechanisms, which set in action the protective system, were established on the cylinders of the shock absorbers of the basic landing gear struts. With their aid was achieved the sag of the energy-consuming crew couches and the deflection forward of the knob of longitudinal-transverse control, which excluded the possibility of the traumatization of pilot. The energing-dissipate armchairs, which are descended on 30 cm, protected crew from the overloads, which appear with the emergency landing. In the emergency was also ensured the forced travmobezopasnoe attraction of pilots to the back of armchair by attachable system.
The selection of the schematic of chassis Mi-28 - tripod with the tailed wheel, was caused by the limitation to the overall sizes of machine, connected with the conditions of its transport. In the construction of the landing gear struts hydropneumatic shock absorbers with the additional emergency motion were included. Lever type basic supports made it possible to change the clearance of helicopter.
The blades of the five-blade rotor had a profile recommended TsAGI, and rectangular planform. The longeron of blade - from the polymeric composite materials formed nose section on the form of profile. To it were attached the rear compartments, made in the form of skin from polymeric composite materials with the polymer filler. Rotor hub was titanium housing with five remote spherical elastomeric hinges. In the moveable connections of bushing widely were used metalloftoroplastovye and tkanievye bearings. Such "maintenance-free" the, i.e., not requiring constant lubricant, bushing for the first time adapted in the domestic helicopter construction. Elastomeric bushing not only made it possible to decrease labor expenses to servicing of helicopter, but also ensured an increase in maneuverability and controllability of machine. (From the application of an alternative torsion bushing on Mi-28 they refused.)
Tail rotor for reduction in noise and increase in the effectiveness was designed four-blade according to X-shaped diagram. Its bushing consisted their two modules, established one above others on the slits of nave. Each module was the articulation of two sleeves of blades. Blade included glass-plastic longeron and tail section from the honeycomb block and the glass-plastic skin. The blades of carrier and tail rotor were equipped with thermoelectric de-icing system. Unfortunately, the development of X-shaped tail rotor was tightened also on the first experiments Mi-28 until 1987. were used tail rotors from Mi-24.
Power plant included two turboshaft engines TVZ-117VM, with the power of 1950 hp each, whose independent work provided the possibility of the execution of flight with one operating engine. At the entrances of engines mushroom-shaped dustproof installations stood. Engines were equipped with the screen- exhaust devices, which decrease thermal distinctness of helicopter. The system of water injection ensured the surge-free work of engines with unguided rocket firings. As the auxiliary power plant was used the engine AI-9V, which ensured also the drive of systems with the checkings on the earth and the heat input air for the cabin heating. In the space of reduction section under the cowl, above the ceiling panel of center fuselage, were arranged the fan and oil radiator.
The fuel system of the Mi-28 was executed in the form two independent balanced systems of the nourishment of each engine with the automatic cross nourishment and the pumping. It consisted of three tanks (two expense to each engine and one general), which were being located in the tank-bay liner, whose walls were protected penorezinoy. Fuel tanks themselves were filled up with polyurethane foam preventing from the explosion.
The special feature of the transmission of helicopter was the presence of two bevel gearboxes UR-28, which are used for the transfer of torque from the engines to the main rotor gearbox VR-28 and being been first stages of reduction.
In control system they were begun to operate four established on the main rotor gearbox of the combined autopilots of drive, who fulfilled the functions of hydraulic amplifiers and control actuators of autopilot. Hydraulic system Mi-28 consisted of two independent systems, which are used for the nourishment of the combined steering drives of the systems of control and hydraulic shock absorber in the system of azimuth guidance. Into the content of the equipment of helicopter entered also the pneumatic system, airconditioning system and oxygen equipment.
The Mi-28 established a set of instrumentation, which made it possible to pilot helicopter and to solve the problems of the aeronavigation at any time of twenty-four hours, also, under any meteorological conditions. The helicopter was equipped for solving of combat missions, and also execution of flights: by the complex of the controlled rocket armament, which includes the combined survey- aiming station, intended for the realization by the navigator-radar operator of search, recognition and target tracking with the launches of the guided missiles and the shooting from the gun; the helmet system of the aim designation of pilot, which ensures control of gun; and the aiming-piloting- navigation complex prPNK-28.
The Ramenskim Instrument-making KB complex created the prPNK-28, which ensured search, detection, recognition of purposes, aimed fire and bombing, an improvement in the piloting characteristics, flight at the predetermined trajectory, fixed hovering above the given point, the stabilization of height, and also continuous position finding. Complex consisted of the sensors of primary information, two onboard computers and devices of control and indication. They were used as the sensors: the information complexes of vertical line, course, altitude-speed parameters, the Doppler speed meter and removal and the helmet system of aim designation. They entered into the composition of the devices of control and indication: automatic plotting board, navigation instruments and the system of mapping information.
The armament of the Mi-28 consisted of non-detachable mobile cannon installation NPPU-28 with the powerful 30-mm gun 2A42, a development Tula KB of instrument manufacture, and system of the detachable armament, hung up on the stores racks of the pylons of wing. Like the majority of the combat helicopters, the Mi-28 was equipped with rotary to the large angles gun, which made it possible to conduct fire from different types of weapon simultaneously along two purposes, which are located on different azimuths (gun it was analogous the established in the combat vehicle infantry of ground forces BMP-2). The spread OF NPPU-28 comprised: along the azimuth of ±110°; on the angle of elevation for +13. - 40°. The ammunition of gun in 250 projectiles was arranged in two boxes with the selective bilateral supply on the rotary part of the ring mount. The extension of ammunition increased the reliability of weapon and the vitality of helicopter.
On the external stores racks was provided for the suspension to 16 anti-tank guided supersonic missiles of 9M120 of complex "Attack-V" or 9M114 of complex "Sturm-V" (with the radio-command guidance systems) development Kolomna KB of machine building, intended for destruction not only ground targets, but also low-flying low-speed aerial targets. To the internal holders could be fastened the units of the unguided rockets B -5V35, B -8V20 or B -13L1, the standardized helicopter nacelles GUV in the machine-gun and grenade-throwing versions, the containers of small loads KMGU-2 with mines and aircraft bombs of small caliber. On the holders also it was possible to transport the aerial bombs of caliber 250 and 500 kgf or extra fuel tanks. During the subsequent years arsenal Mi-28 was supplemented by the heavy unguided rockets S -24b, cannon containers UPK-23-250 and igniting tanks ZB-500.
Protection from defeat by the guided missiles on Mi-28 was ensured by equipment for setting of radar jamming and to the guided missiles with the infrared and radar homing heads; equipment for warning about the irradiation of helicopter by radars and by the laser target indicators of enemy; the device of the shooting of interference cartridges UV-26 for the protection from the heat-seeking missiles.
Important value with the development of helicopter was given to convenience in the maintenance under the conditions of autonomous basing. In comparison with Mi-24 the labor expense for maintenance was lowered approximately three times.
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