Monday, February 9, 2009

Mil Mi-24

The Mil Mi-24 (Cyrillic Миль Ми-24, NATO reporting name "Hind") is a large helicopter gunship and low-capacity troop transport produced by Mil Moscow Helicopter Plant and operated from 1972 by the Soviet Air Force, its successors, and over thirty other nations. In October 2007, the Russian Air Force announced it would replace its 250 Mi-24 helicopter gunships with 300 more modern Mi-28s and possibly Ka-50s by 2015.
In NATO circles the export versions, Mi-25 and Mi-35, are simply denoted with a letter suffix as "Hind D" and "Hind E" respectively. Soviet pilots called the aircraft летающий танк (letayushchiy tank, “flying tank”). More common unofficial nicknames were Крокодил (Krokodil, “Crocodile”), due to the helicopter's new camouflage scheme and Стакан (Stakan, “Glass”), because of the flat glass plates which surrounded the three place cockpit of the Hind A version.


Design
The core of the aircraft was derived 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 configuration gave the aircraft its distinctive double air intake. Original versions have an angular greenhouse-style cockpit; Model D and later have a characteristic tandem cockpit with a "double bubble" canopy. Other airframe components came from the Mi-14 "Haze". Two mid-mounted stub wings provide weapon hardpoints, each offering three stations, in addition to providing lift. The load-out mix is mission dependent; Hinds 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 .50 caliber (12.7 mm) rounds. The cockpit is overpressurized to protect the crew in NBC conditions.
Considerable attention was given to making the Mi-24 fast. The airframe was streamlined, and fitted with retractable tricycle undercarriage landing gear to reduce drag. The wings provide considerable lift at high speed, up to a quarter of total lift. The main rotor was tilted 2.5° to the right from the fuselage to counteract dissymmetry of lift at high speed and provide a more stable firing platform. The landing gear was also tilted to the left so the rotor would still be level when the aircraft was on the ground, making the rest of the airframe tilt to the left. The tail was also asymmetrical to give a side force at speed, thus unloading the tail rotor.
As a combination gunship and troop transport, the Mi-24 has no direct NATO counterpart. While some have compared the UH-1 ("Huey") as NATO's direct counterpart to the Mi-24, this is inaccurate. While UH-1s were used in Vietnam to ferry troops, and were used as gunships, they were not able to do both at the same time. Converting a UH-1 into a gunship meant stripping the entire passenger area to accommodate extra fuel and ammunition, making it useless for troop transport. The Mi-24 was designed to do both, and this was greatly exploited by airborne units of the Soviet Army during the 1980-1989 Soviet invasion of Afghanistan. The closest Western equivalent was the Sikorsky S-67 Blackhawk, which utilized many of the same design principles and was also built as a high-speed, high-agility attack helicopter with limited troop transport capability; it, like the Mi-24, was also designed using many components from an already existing product, the Sikorsky S-61, itself a close approximation to the Mi-8/Mi-14. The S-67, however, was never adopted for service.


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