The Mil Mi-24 (Russian: Миль Ми-24; NATO reporting name: Hind) is a large helicopter gunship, attack helicopter and low-capacity troop transport with room for eight passengers.[1] It is produced by Mil Moscow Helicopter Plant and was introduced by the Soviet Air Force in 1972. The helicopter is currently in use by 58 countries.
In NATO circles, the export versions, Mi-25 and Mi-35, are denoted with a letter suffix as "Hind D" and "Hind E". Soviet pilots called the Mi-24 the "flying tank" (Russian: летающий танк, romanized: letayushchiy tank), a term used historically with the famous World War II Soviet Il-2 Shturmovik armored ground attack aircraft. Other common unofficial nicknames were "Galina" (or "Galya"), "Crocodile" (Russian: Крокодил, romanized: Krokodil), due to the helicopter's camouflage scheme, and "Drinking Glass" (Russian: Стакан, romanized: Stakan), because of the flat glass plates that surround earlier Mi-24 variants' cockpits.[2]
During the early 1960s, it became apparent to Soviet designer Mikhail Mil that the trend towards ever-increasing battlefield mobility would result in the creation of flying infantry fighting vehicles, which could be used to perform both fire support and infantry transport missions. The first expression of this concept was a mock-up unveiled in 1966 in the experimental department of the Ministry of Aircraft's factory number 329, where Mil was head designer. The mock-up designated V-24 was based on another project, the V-22 utility helicopter, which never flew. The V-24 had a central infantry compartment that could hold eight troops sitting back to back, and a set of small wings positioned to the top rear of the passenger cabin, capable of holding up to six missiles or rockets and a twin-barreled GSh-23L cannon fixed to the landing skid.
Mil proposed the design to the heads of the Soviet armed forces. While he had the support of a number of strategists, he was opposed by several more senior members of the armed forces, who believed that conventional weapons were a better use of resources. Despite the opposition, Mil managed to persuade the defence minister's first deputy, Marshal Andrey A. Grechko, to convene an expert panel to look into the matter. While the panel's opinions were mixed, supporters of the project eventually held sway and a request for design proposals for a battlefield support helicopter was issued. The development and use of gunships and attack helicopters by the US Army during the Vietnam War convinced the Soviets of the advantages of armed helicopter ground support, and fostered support for the development of the Mi-24.[3]
Mil engineers prepared two basic designs: a 7-ton single-engine design and a 10.5-ton twin-engine design, both based on the 1,700 hp Izotov TV3-177A turboshaft. Later, three complete mock-ups were produced, along with five cockpit mock-ups to allow the pilot and weapon station operator positions to be fine-tuned.
The Kamov design bureau suggested an army version of their Ka-25 ASW helicopter as a low-cost option. This was considered but later dropped in favor of the new Mil twin-engine design. A number of changes were made at the insistence of the military, including the replacement of the 23 mm cannon with a rapid-fire heavy machine gun mounted in a chin turret, and the use of the 9K114 Shturm (AT-6 Spiral) anti-tank missile.
A directive was issued on 6 May 1968 to proceed with the development of the twin-engine design. Work proceeded under Mil until his death in 1970. Detailed design work began in August 1968 under the codename Yellow 24. A full-scale mock-up of the design was reviewed and approved in February 1969. Flight tests with a prototype began on 15 September 1969 with a tethered hover, and four days later the first free flight was conducted. A second prototype was built, followed by a test batch of ten helicopters.
Acceptance testing for the design began in June 1970, continuing for 18 months. Changes made in the design addressed structural strength, fatigue problems and vibration levels. Also, a 12-degree anhedral was introduced to the wings to address the aircraft's tendency to Dutch roll at speeds in excess of 200 km/h (124 mph), and the Falanga missile pylons were moved from the fuselage to the wingtips. The tail rotor was moved from the right to the left side of the tail, and the rotation direction reversed. The tail rotor now rotated up on the side towards the front of the aircraft, into the downwash of the rotor, which increased its efficiency. A number of other design changes were made until the production version Mi-24A (izdeliye 245) entered production in 1970, obtaining its initial operating capability in 1971 and was officially accepted into the state arsenal in 1972.[4]
In 1972, following completion of the Mi-24, development began on a unique attack helicopter with transport capability. The new design had a reduced transport capability (three troops instead of eight) and was called the Mi-28, and that of the Ka-50 attack helicopter, which is smaller and more maneuverable and does not have the large cabin for carrying troops. In October 2007, the Russian Air Force announced it would replace its Mi-24 fleet with Mi-28Ns and Ka-52s by 2015.[5][6] However, after the successful operation of the type in Syria it was decided to keep it in service and upgrade it with new electronics, sights, arms and night vision goggles.[7]
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The core of the aircraft was derived from the Mil Mi-8 (NATO reporting name "Hip") with two top-mounted turboshaft engines driving a mid-mounted 17.3 m (57 ft) 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 loadout mix is mission dependent; Mi-24s can be tasked with close air support, anti-tank operations, or aerial combat.
The Mi-24's titanium rotor blades are resistant to 12.7 mm (.50 caliber) rounds.[citation needed] The cockpit is protected by ballistic-resistant windscreens and a titanium-armored tub.[8] The cockpit and crew compartment are overpressurized to protect the crew in NBC conditions.[9]
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. At high speed, the wings provide considerable lift (up to a quarter of total lift). The main rotor was tilted 2.5° to the right from the fuselage to compensate for translating tendency at a hover. The landing gear was also tilted to the left so that 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.[10]
A modified Mi-24B, named A-10, was used in several speed and time-to-climb world record attempts. The helicopter had been modified to reduce weight as much as possible—one measure was the removal of the stub wings.[4] The previous official speed record was set on 13 August 1975 over a closed 1,000 km (620 mi) course of 332.65 km/h (206.70 mph); many of the female-specific records were set by the all-female crew of Galina Rastorguyeva and Lyudmila Polyanskaya.[11] On 21 September 1978, the A-10 set the absolute speed record for helicopters with 368.4 km/h (228.9 mph) over a 15/25 km course. The record stood until 1986, when it was broken by the current official record holder, a modified British Westland Lynx.[12]
As a combination of armoured gunship and troop transport, the Mi-24 has no direct NATO counterpart. While the UH-1 ("Huey") helicopters were used by the US in the Vietnam War either to ferry troops, or 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, and removing its troop transport capability. The Mi-24 was designed to do both, and this was greatly exploited by airborne units of the Soviet Army during the 1980–89 Soviet–Afghan War. The closest Western equivalent was the American Sikorsky S-67 Blackhawk, which used many of the same design principles and was also built as a high-speed, high-agility attack helicopter with limited troop transport capability using many components from the existing Sikorsky S-61. The S-67, however, was never adopted for service.[1] Other Western equivalents are the Romanian Army's IAR 330, which is a licence-built armed version of the Aérospatiale SA 330 Puma, and the MH-60 Direct Action Penetrator, a special purpose armed variant of the Sikorsky UH-60 Black Hawk.
The first combat use of the Mi-24 was with the Ethiopian forces during the Ogaden War against Somalia. The helicopters formed part of a massive airlift of military equipment from the Soviet Union, after the Soviets switched sides towards the end of 1977. The helicopters were instrumental in the combined air and ground assault that allowed the Ethiopians to retake the Ogaden by the beginning of 1978.[13]
The Libyan air force used Mi-24A and Mi-25 units during their numerous interventions in Chad's civil war.[10] The Mi-24s were first used in October 1980 in the battle of N'Djamena, where they helped the People's Armed Forces seize the capital.
In March 1987, the Armed Forces of the North, which were backed by the US and France, captured a Libyan air force base at Ouadi-Doum in Northern Chad. Among the aircraft captured during this raid were three Mi-25s. These were supplied to France, which in turn sent one to the United Kingdom and one to the US.[4]
The aircraft was operated extensively during the Soviet–Afghan War, mainly for bombing Mujahideen fighters. When the U.S. supplied heat-seeking Stinger missiles to the Mujahideen, the Soviet Mi-8 and Mi-24 helicopters proved to be favorite targets of the rebels.
It is difficult to find the total number of Mi-24s used in Afghanistan.[14] At the end of 1990, the whole Soviet Army had 1,420 Mi-24s.[15] During the Afghan war, sources estimated the helicopter strength to be as much as 600 units, with up to 250 being Mi-24s,[16] whereas a (formerly secret) 1987 Central Intelligence Agency (CIA) report says that the number of Mi-24s in theatre increased from 85 in 1980 to 120 in 1985.[17]
In April 1979, Mi-24s were supplied to the Afghan government to deal with Mujahideen guerrillas.[18] The Afghan pilots were well-trained and made effective use of their machines, but the Mujahideen were not easy targets. The first Mi-24 to be lost in action was shot down by guerrillas on 18 July 1979.[19][20]
Despite facing strong resistance from Afghan rebels, the Mi-24 proved to be very destructive. The rebels called the Mi-24 "Shaitan-Arba (Satan's Chariot)".[18] In one case, an Mi-24 pilot who was out of ammunition managed to rescue a company of infantry by maneuvering aggressively towards Mujahideen guerrillas and scaring them off. The Mi-24 was popular with ground troops, since it could stay on the battlefield and provide fire as needed, while "fast mover" strike jets could only stay for a short time before heading back to base to refuel.
The Mi-24's favoured munition was the 80-millimetre (3.1 in) S-8 rocket, the 57 mm (2.2 in) S-5 having proven too light to be effective. The 23 mm (0.91 in) gun pod was also popular. Extra rounds of rocket ammunition were often carried internally so that the crew could land and self-reload in the field. The Mi-24 could carry ten 100-kilogram (220 lb) iron bombs for attacks on camps or strongpoints, while harder targets could be dealt with a load of four 250-kilogram (550 lb) or two 500-kilogram (1,100 lb) iron bombs.[21] Some Mi-24 crews became experts at dropping bombs precisely on targets. Fuel-air explosive bombs were also used in a few instances, though crews initially underestimated the sheer blast force of such weapons and were caught by the shock waves. The 9K114 Shturm was used infrequently, largely due to a lack of targets early in the war that required the precision and range the missile offered and a need to keep to stocks of anti tank missiles in Europe. After the Mujahideen got access to more advanced anti aircraft weapons later in the war the Shturm was used more often by Mi-24 units.[22]
Combat experience quickly demonstrated the disadvantages of having an Mi-24 carrying troops. Gunship crews found the soldiers a concern and a distraction while being shot at, and preferred to fly lightly loaded anyway, especially given their operations from high ground altitudes in Afghanistan. Mi-24 troop compartment armour was often removed to reduce weight. Troops would be carried in Mi-8 helicopters while the Mi-24s provided fire support.
It proved useful to carry a technician in the Mi-24's crew compartment to handle a light machine gun in a window port. This gave the Mi-24 some ability to "watch its back" while leaving a target area. In some cases, a light machine gun was fitted on both sides to allow the technician to move from one side to the other without having to take the machine gun with him.
This weapon configuration still left the gunship blind to the direct rear, and Mil experimented with fitting a machine gun in the back of the fuselage, accessible to the gunner through a narrow crawl-way. The experiment was highly unsuccessful, as the space was cramped, full of engine exhaust fumes, and otherwise unbearable. During a demonstration, an overweight Soviet Air Force general got stuck in the crawl-way.[4] Operational Mi-24s were retrofitted with rear-view mirrors to help the pilot spot threats and take evasive action.
Besides protecting helicopter troop assaults and supporting ground actions, the Mi-24 also protected convoys, using rockets with flechette warheads to drive off ambushes; performed strikes on predesignated targets; and engaged in "