Mi-24 HIND - Design
The Mi-24 prototype was a classic single-rotor design helicopter with two turbine engines. Its design is a classic one with a five-bladed main rotor and three-bladed tail rotor. The core of the aircraft was taken from the Mil Mi-8 (NATO reporting name "Hip"), two top mounted turboshaft engines driving a mid-mounted 17.3 m five-blade main rotor and a three blade tail rotor. The engine positions give the aircraft its distinctive double air intake. The five-blade main rotor is mounted on top of fuselage midsection, while short, stubby, weapon-carrying wings are mounted at the fuselsage midsection. It is powered by TV3-117 engines (2 x 1638 kW). The two turboshaft engines are mounted above body midsection with two round air intakes located just above the cockpit and exhaust ports on the sides of engines. The Hind A fuselage consists of a large, oval-shaped body with a glassed-in cockpit, tapering at the rear to the tail boom. The swept-back tapered tail fin features a rotor on the right on some models, with tapered flats on a boom just forward of the fin. The flight control system uses conventional helicopter style flight controls with positive mechanical linkage, hydraulic boost, and a limited authority automatic flight control system (designed to improve helicopter stability and control as well as reduce pilot workload).
External stores are mounted on underwing external stores points. Each wing has three hardpoints for a total of six stations. A representative mix when targeting armor formations would be eight AT-6 ATGMs, 750x 30-mm rounds, and two 57-mm rocket pods. The aircraft can store an additional ammunition basic load in the cargo compartment in lieu of carrying troops. Armored cockpits and titanium rotor head able to withstand 20-mm cannon hits. Every aircraft has an over-pressurization system for operation in a NBC environment.
Weapon hardpoints are provided by two short mid-mounted wings (which also provide lift), each offering three stations. The load-out mix is mission dependent; the Hind can be tasked with close air support, anti-tank operations, or aerial combat. The body is heavily armored and the titanium rotor blades can resist impacts from 12.7 mm rounds. The Hind has only three known vulnerable points: the turbine intakes, the tail rotor assembly, and an oil tank inexplicably but conveniently located beneath the red star on the fuselage. The cockpit is overpressurized to protect the crew in NBC conditions. It is equipped with a hydraulically retractable tricycle type landing gear with a twin-wheel nose unit.
The helicopter has a wing with a span of 6.536 m, which can relieve the tail rotor by up to 30 per cent in higher speeds. The HIND's wings provide 22% to 28% of its lift in forward flight. In a steep banking turn at slower airspeeds, the low wing can lose lift while it is maintained on the upper wing, resulting in an excessive roll. This is countered by increasing forward airspeed to increase lift on the lower wing. Because of this characteristic, and the aircraft's size and weight, it is not easily maneuverable. Therefore they usually attack in pairs or multiple pairs, and from various directions.
Based on studies conducted, the design bureau collective and its leader considered this design optimal for a combat helicopter, including from the standpoint of survivability in combat. If one of the engines are damaged, the crew canin principle, continue to carry out the combat operation. Flight is ensured by the second, automatically switched to maximum power mode. If both engines fail, the helicopter, possessing excellent autorotation qualities of the main rotor system and good directional controllability during autorotation, provided by the tail rotor which continues to operate, could make a landing even on a small landing pad. If the tail rotor is lost, it can continue flying with forward speed and execute a landing like an airplane. The booster elements of the main rotor control system, relatively more powerful than twin-rotor helicopters with the same weight, make the single-rotor design more preferable for combat survivability.
M.L. Mil considered the slight increase in the lateral area of the helicopter at the expense of the tail boom to be insignificant. It is notlikely that anyone would deliver aimed fire specially atthe boom, which is narrow compared to the fuselage, andat the tail rotor power drive passing through it, since the hit probability is very low. Designers of combat helicopters in the West were apparently also guided by similar considerations later on. All the existing helicopters of this sort, for example, the Huey Cobra, Apache, and Mangouste, as well as those being newly designed, are built or being built using this design. Unlike his previous helicopters, M.L. Mil rearranged the work stations of the two crew members on the Mi-24, one behind the other. This reduced aerodynamic drag and at the same time decreased the likelihood of both of the flight crew being hit simultaneously from the most dangerous direction - from the front. Now this seating configuration of helicopter crews has become practically universal.
A cabin designed for several riflemen is located behind the flight crew cockpit. Its specially designed doors enable the riflemen to abandon the helicopter quickly on landing. Both cabins have sufficiently powerful armor to protect the flight crew and the assault troops from small-arms fire and shrapnel.
The helicopter has dual controls to increase its survivability in combat. If the commander occupying the rear seat is wounded, theweapon operator seated in front assumes control of the helicopter. The Mi-24 helicopters were equipped with the most modern machinegun and missile armament. There are hardpoints on the short wings for four rocket pods. Aviation bombs can be mounted in place of them. There are hardpoints at the ends of the wings for guided missiles (ATGMs). The nose section of the flight crew cabin has a swinging machinegun mount-a large-caliber machinegun. At each window in the cabin for the assault troops there is a pin mount which can be used to fire personal weapons directly from onboard the helicopter.
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