The helicopter had its first significant impact on military operations during the Korean War, but it came of age in Vietnam. Helicopters fielded air-mobile infantry units, evacuated casualties, hauled artillery and ammunition, rescued downed aviators, and served as ground-attack craft. Helicopters became serious operational machines only after American manufacturers fitted them with gas-turbine engines, which were much less sensitive than piston engines to high temperatures and low atmospheric density, had far greater power-to-weight ratios, and occupied considerably less space.
Assault and attack helicopters
The mainstay of U.S. Army assault units in Vietnam was the Bell UH-1 Iroquois, popularly known as the Huey. As early as 1962, army aviators were adding turret-mounted automatic 40-mm grenade launchers, skid-mounted rocket pads, and remotely trainable 7.62-mm machine guns. These experiments, which proved effective in supporting helicopter assault operations, led to the AH-1G HueyCobra, deployed in 1967 as the first purpose-built helicopter gunship. With its pilot seated behind and above the gunner, the HueyCobra pioneered the tandem stepped-up cockpit configuration of future attack helicopters.
After the Vietnam War the lead in gunship design passed to the Soviet Union, which, in the Afghan War of the 1980s, fielded the Mil Mi-24 Hind, the fastest and possibly most capable helicopter gunship of its time. A primary role of the Hind was to attack armoured vehicles; to this end it mounted guided antitank missiles on stub wings projecting from the fuselage. In addition to the two-man cockpit configuration of the HueyCobra, it had a small passenger and cargo bay that gave it a limited troop-transport capability. Later the Soviets produced the Mi-28 Havoc, a refinement of the Hind that, with no passenger bay, was purely a gunship.
The successor to the HueyCobra was the McDonnell Douglas AH-64 Apache, a heavily armoured antiarmour helicopter with less speed and range than the Hind but with sophisticated navigation, ECM, and fire-control systems. The Apache became operational in 1986 and proved highly effective in the Persian Gulf War (1990–91).
Naval helicopters
Helicopters have been adapted extensively to antisubmarine roles, given the capability of “dipping” sonar sensors into the water to locate their targets and launching self-homing torpedoes to destroy them. Ship-borne helicopters also serve as firing platforms for antiship missiles and are used to carry warning and surveillance radars, typically sharing information with their mother ships. By firing heat-producing or chaff flares to confuse infrared and radar homing systems, naval helicopters can serve as decoys for antiship missiles.