The Lockheed AH-56 Cheyenne is an attack helicopter developed by Lockheed for the United States Army. It rose from the Army’s Advanced Aerial Fire Support System (AAFSS) program to field the service’s first dedicated attack helicopter. Lockheed designed the Cheyenne using a four-blade rigid-rotor system and configured the aircraft as a compound helicopter with low-mounted wings and a tail-mounted thrusting propeller driven by a General Electric T64 turboshaft engine.
source.image: Found And Explained
Prior to the development of the AH-56, all armed helicopters had been modifications to existing aircraft designed for unarmed uses. In 1962, then U.S. Secretary of Defense Robert McNamara convened the Howze Board to review Army aviation requirements. The board recommended an airmobile division supported by 90 armed helicopters.
Based on the guidance from the Secretary of the Army, CDC established Qualitative Material Development Objectives (QMDO) for a rotary-wing aircraft with 361 km/h cruise speed, 410 km/h dash speed, and the capability to hover out-of-ground-effect (OGE) at 1,800 m on a 35 °C day. The speed requirements were derived from the speed of aircraft the helicopter would escort.
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Lockheed designed the Cheyenne as a compound helicopter, which combines a helicopter with fixed-wing features for increased performance, usually speed. The Cheyenne had a two-seat tandem cockpit featuring an advanced navigation and fire control suite. The tandem seating placed the pilot in the rear seat, and the gunner in the front seat. The Cheyenne achieved speeds over 200 knots (230 mph; 370 km/h), but as a compound helicopter was unable to qualify for speed records in helicopter categories.
