Lockheed AH-56 (Cheyenne)

An attack helicopter developed for the United States Army by Lockheed which is known as Lockheed AH-56 Cheyenne rose from the Army's Advanced Aerial Fire Support System (AAFSS) program in order to field the service's first dedicated attack helicopter.

Cheyenne was designed by Lockheed to use a four-blade rigid-rotor system. Lockheed configured the aircraft as a compound helicopter. This aircraft also featured a tail-mounted thrusting propeller, low-mounted wings, and a single General Electric T64 turboshaft engine. In order to provide armed escort for the Army's transport helicopters, such as the Bell UH-1 Iroquois, the Cheyenne was to have a high-speed dash capability.

SPECIFICATIONS:

Armament: Guns: 1) One nose turret with either an M129 40 mm (1.57 in) grenade launcher or an XM196 7.62x51 mm machine gun 2) One belly turret with an XM140 30 mm (1.18 in) cannon | Hard-points: Six | Missiles : BGM-71 TOW missiles | Rockets : 2.75 in (70 mm) FFA rockets
Engine: One General Electric T64-GE-16 turboshaft, 3,925 shp (2,930 kW)
Rotor systems: 4 blades on main rotor, 4 blades on tail rotor, 3 blades on pusher propeller
Maximum speed: 244 mph
Range: 1,225 miles
Service ceiling: 20,000 ft.
Length: 54 ft. 8 in.
Height: 13 ft. 8.5 in.
Weight: 18,300 lbs. loaded
Cruise speed: 255 mph
Rotor diameter: 51 ft. 3 in.
Fuel capacity: Internal: 7,320 L of JP-5 fuel | External: Two 1,136 L tanks
Crew: Two (one pilot, one copilot/gunner [front seat])

The Army awarded Lockheed a contract for ten AH-56 prototypes in 1966 and a production contract, based on flight testing progress later in January 1968. The AH-56's first flight took place on 21 September 1967. On 19 May 1969, the production contract of Cheyenne was being canceled due to a fatal crash and technical problems affecting performance. Due to the problems too, Cheyenne development had been put behind schedule. However, the development of the Cheyenne continued with the hope that the helicopter would eventually enter service.

The Army canceled the Cheyenne program on 9 August 1972 due to the controversy with the United States Air Force over the Cheyenne's role in combat as well as the political climate regarding military acquisition programs. These were the reasons that had caused the Army to correct the service's attack helicopter requirements in favor of a twin-engined conventional helicopter which was viewed as less technical and more survivable. On 17 August 1972, the Army announced a new program for an Advanced Attack Helicopter (AAH) which led to the development of the AH-64 Apache.