Attack helicopter
An attack helicopter is an armed helicopter with the primary role of an attack aircraft, with the offensive capability of engaging ground targets such as enemy infantry, military vehicles and fortifications. Due to their heavy armament they are sometimes called helicopter gunships.
Attack helicopters can use weapons including autocannons, machine guns, rockets, and anti-tank missiles such as the AGM-114 Hellfire. Some attack helicopters are also capable of carrying air-to-air missiles, though mostly for purposes of self-defense against other helicopters and low-flying light combat aircraft.
A modern attack helicopter has two primary roles: first, to provide direct and accurate close air support for ground troops; and second, the anti-tank role to destroy grouped enemy armored vehicles. Attack helicopters are also used as protective escort for transport helicopters, or to supplement lighter helicopters in the armed reconnaissance roles. In combat, an attack helicopter is projected to destroy targets worth around 17 times its own production cost before being destroyed.
Development
Background
Low-speed, fixed wing Allied aircraft like the Soviet Polikarpov Po-2 training and utility biplane had been used as early as 1942 to provide night harassment attack capability against the Wehrmacht Heer on the Eastern Front, most effectively in the Battle of the Caucasus as exemplified by the Night Witches all-female Soviet air unit. Following Operation Overlord in 1944, the military version of the similarly slow-flying Piper J-3 Cub high-wing civilian monoplane, the L-4 Grasshopper, begun to be used in a light anti-armor role by a few U.S. Army artillery spotter units over France; these aircraft were field-outfitted with either two or four bazooka rocket launchers attached to the lift struts, against German armored fighting vehicles. During the summer of 1944, U.S. Army Major Charles Carpenter managed to successfully take on an anti-armor role with his rocket-armed Piper L-4. His L-4, bearing US Army serial number 43-30426 and named Rosie the Rocketer, armed with six bazookas, had notable success in an engagement during the Battle of Arracourt on September 20, 1944, employing top attack tactics in knocking out at least four German armored vehicles, as a pioneering example of taking on heavy enemy armor from a slow-flying aircraft.The Germans were also engaged in such ad hoc low-speed light aircraft platforms for ground attack very late in the war, with one subtype of the Bücker Bestmann trainer—the Bü 181C-3—armed with four Panzerfaust 100 anti-tank grenade launchers, two under each of the low-winged monoplane's wing panels, for the concluding two months of the war in Europe. This sort of role, being undertaken by low-speed fixed-wing light aircraft was something that was also likely to be achievable after World War II, from the increasing numbers of post-war military helicopter designs. The only American helicopter in use during the war years, the Sikorsky R-4, was only being used for rescue and were still very much experimental in nature.
In the early 1950s, various countries around the world started to make increased use of helicopters in their operations in transport and liaison roles. Later on it was realised that these helicopters, successors to the World War II-era Sikorsky R-4, could be armed with weapons in order to provide them with limited combat capability. Early examples include armed Sikorsky H-34s in service with the US Air Force and armed Mil Mi-4 in service with the Soviet Air Forces. This "experimental" trend towards the development of dedicated attack helicopters continued into the 1960s with the deployment of armed Bell UH-1s and Mil Mi-8s during the Vietnam War, to this day the pair of most produced helicopter designs in aviation history. Bell helicopter employee and Vietnam war veteran, Billy "Bill" Frank Perkins, though more widely unknown, was the first person to ever fly an attack helicopter; he is in possession of an official certificate stating so. These helicopters proved to be moderately successful in these configurations, but due to a lack of armor protection and speed, they were ultimately ineffective platforms for mounting weapons in higher-threat ground combat environments.
Since the 1960s, various countries around the world started to design and develop various types of helicopters with the purpose of providing a heavily armed and protected aerial vehicle that can perform a variety of combat roles, from reconnaissance to aerial assault missions. By the 1990s, the missile-armed attack helicopter evolved into a primary anti-tank weapon. Able to quickly move about the battlefield and launch fleeting "pop-up attacks", helicopters presented a major threat even with the presence of organic air defenses. The helicopter gunship became a major tool against tank warfare, and most attack helicopters became more and more optimized for the antitank mission.
United States
Amid the opening months of the Korean War era, during August 1950, a joint US Navy and Marine Corps test used a newly acquired Bell HTL-4 helicopter to test if a bazooka could be fired from a helicopter in flight. One of the larger 3.5 inch models of the bazooka was chosen, and was mounted ahead and to the right of the helicopter to allow the door to remain clear. The bazooka was successfully tested, although it was discovered that it would require shielding for the engine compartment, which was exposed in the model 47 and other early helicopters. The helicopter itself belonged to HMX-1, a Marine experimental helicopter squadron.In the mid-1960s, the U.S. Army concluded that a purpose-built attack helicopter with more speed and firepower than current armed helicopters was required in the face of increasingly intense ground fire from Viet Cong and NVA troops. Based on this realization, and with the growing involvement in Vietnam, the U.S. Army developed the requirements for a dedicated attack helicopter, the Advanced Aerial Fire Support System. The aircraft design selected for this program in 1965, was Lockheed's AH-56 Cheyenne.
As the Army began its acquisition of a dedicated attack helicopter, it sought options to improve performance over the continued use of improvised interim aircraft. In late 1965, a panel of high-level officers was selected to evaluate several prototype versions of armed and attack helicopters to determine which provided the most significant increase in capability to the UH-1B. The three highest-ranked aircraft, the Sikorsky S-61, Kaman H-2 "Tomahawk", and the Bell AH-1 Cobra, were selected to compete in flight trials conducted by the Army's Aviation Test Activity. Upon completion of the flight evaluations, the Test Activity recommended Bell's Huey Cobra to be an interim armed helicopter until the Cheyenne was fielded. On 13 April 1966, the U.S. Army awarded Bell Helicopter Company a production contract for 110 AH-1G Cobras. The Cobra had a tandem cockpit seating arrangement to make the aircraft a smaller frontal target, increased armor protection, and greater speed.
In 1967, the first AH-1Gs were deployed to Vietnam, around the same time that the Cheyenne successfully completed its first flight and initial flight evaluations. And while the Cheyenne program suffered setbacks over the next few years due to technical problems, the Cobra was establishing itself as an effective aerial weapons platform, despite its performance shortcomings compared to the AH-56 and design issues of its own. The cost estimates of the AH-56 increased substantially. By 1972, when the Cheyenne program was eventually cancelled to make way for the Advanced Attack Helicopter, the interim AH-1 "Snake" had built a solid reputation as an attack helicopter. In June 1972 the USMC began deploying AH-1J SeaCobra Attack Helicopters for combat operations in South Vietnam.
During the late 1970s, the U.S. Army saw the need of more sophistication within the attack helicopter corps, allowing them to operate in all weather conditions. Although AH-1Gs served well, they proved vulnerable even in a mid-intensity environment. With that the Advanced Attack Helicopter program started, aiming for a more durable, more advanced, longer range, stronger close air support helicopter, capable of destroying armored formations. It would be capable of carrying the new AGM-114 Hellfire and night fighting capabilities. From this program the Hughes YAH-64 came out as the winner. The prototype YAH-64 was first flown on 30 September 1975. The U.S. Army selected the YAH-64 over the Bell YAH-63 in 1976, and later approved full production in 1982. After purchasing Hughes Helicopters in 1984, McDonnell Douglas continued and turned it into the AH-64 Apache production and development. The helicopter was introduced to U.S. Army service in April 1986.
Today, the US attack helicopter has been further refined, and the AH-64D Apache Longbow demonstrates many of the advanced technologies being considered for deployment on future gunships. The US Marine Corps also continued to employ attack helicopters in the direct fire support role, in the form of the AH-1 Super Cobra. While helicopters were effective tank-killers in the Middle East, attack helicopters are being seen more in a multipurpose role. Tactics, such as tank plinking, showed that fixed-wing aircraft could be effective against tanks, but helicopters retained a unique low-altitude, low-speed capability for close air support. Other purpose-built helicopters were developed for special operations missions, including the MH-6 for extremely close support.
Soviet Union and its successor states
During the early 1960s, Soviet engineers started experimenting with various designs aimed at producing an aerial vehicle that could provide battlefield mobility for infantry and provide fire support to army forces on the ground. The first of these concepts was a mock-up unveiled in 1966 in the experimental shop of the Ministry of Aircraft's factory number 329, where Mikhail Leont'yevich Mil was head designer. The mock-up, which was designated V-24, was based on another project, the V-22 utility helicopter, which itself never entered production. The V-24 had an infantry transport 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 rocket pods, along with a twin-barrel GSh-23L cannon fixed to the landing skid.These designs were proposed by Mil to the Soviet armed forces, and 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 of gunships and attack helicopters by the US Army during the Vietnam War convinced the Soviets of the advantages of armed helicopter ground support doctrine, which had a positive influence on moving forward with the development of the Mil Mi-24. After several mock-ups were produced, a directive was issued on 6 May 1968 to proceed with development of a twin-engine design of the helicopter. 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. A number of other design changes were made until the production version Mi-24A entered production in 1970, obtaining its initial operating capability in 1971 and was officially accepted into the state arsenal in 1972. Numerous versions have been developed to this day.
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 and was called the Mil Mi-28.
File:Mi-28N from Berkuti aerobatics team.jpg|thumb|left|A Russian Mil Mi-28N. The Mil Mi-28 along with the Ka-50 represented the first dedicated attack helicopter of the Soviet Air Forces in the 1980s.
In 1977, a preliminary design of the Mil Mi-28 was chosen, in a classic single-rotor layout. Its transport capability was removed and it lost its similarity to the Mi-24. Design work on the Mi-28 began under Marat Tishchenko in 1980. In 1981, a design and a mock-up were accepted. The prototype was first flown on 10 November 1982. In this same time frame, Kamov was also attempting to submit its own designs for a new helicopter to the military, which they had designed throughout the early and mid 1980s. In 1984, the Mi-28 completed the first stage of state trials, but in October 1984 the Soviet Air Force chose the more advanced Kamov Ka-50 as the new anti-tank helicopter. The Mi-28 development was continued, but given lower priority. In December 1987 Mi-28 production in Rosvertol in Rostov-on-Don was approved. After several prototypes were built, production ceased in 1993 with additional development continuing into the 21st century. Changes in the military situation after the Cold War made specialized anti-tank helicopters less useful. The advantages of the Mi-28N, like all-weather action ability, lower cost, and similarity to the Mi-24, have become more important. In 2003, the head of Russian Air Force stated that the Mi-28N and Ka-50 attack helicopters will become the standard Russian attack helicopter. The first serial Mi-28N was delivered to the Army on 5 June 2006.