AH-56 Cheyenne

The AH-56 Cheyenne was a four-bladed, single-engine attack helicopter developed by Lockheed for the United States Army's Advanced Aerial Fire Support System (AAFSS) program to produce the Army's first dedicated attack helicopter. Lockheed designed the AH-56 utilizing a rigid-rotor and configured the aircraft as a compound helicopter; with low-mounted wings and a tail-mounted thrusting propeller. The compound helicopter design was powered by a GE T64turboshaft engine and was intended to provide a 212-knot (244 mph, 393 km/h) dash capability in order to serve as an armed escort to the Army's transport helicopters, such as the UH-1 Iroquois.

The AH-56 was armed with a 30 mm (1.18 in) cannon in a belly turret and either a 7.62 mm (.308 in) minigun or a 40 mm (1.57 in) grenade launcher in a nose turret. Two hardpoints under each wing were capable of mounting 2.75 inch (70 mm) rocket launchers and TOW missiles. Two additional hardpoints under the fuselage were equipped for carrying external fuel tanks.

In 1966, the Army awarded Lockheed a contract to develop 10 prototypes of the AH-56. The first flight of an AH-56 occurred on 21 September 1967. In January 1968, the Army awarded Lockheed a production contract, based on flight testing progress. A fatal crash and technical problems affecting performance put Cheyenne development behind schedule, resulting in the production contract being canceled on 19 May 1969. Cheyenne development continued in the hope that the helicopter would eventually enter service.

On 9 August 1972, the Army canceled the Cheyenne program. Controversy over the Cheyenne's role in combat, as well as the political climate regarding military acquisition programs had caused the Army to amend the service's attack helicopter requirements in favor of a twin-engine, conventional helicopter; viewed as less technical and more survivable. The Army announced a new program for an Advanced Attack Helicopter on 17 August 1972.

Prior to the development of the AH-56, all armed helicopters had been modifications to existing aircraft designed for unarmed uses. In 1962, then Secretary of Defense McNamara convened the Howze Board to review Army aviation requirements. The results of the board envisioned an airmobile division that was supported by 90 armed aircraft. The recommendation of the Howze Board came at the same time the Army was preparing to deploy its first armed escort helicopters to Vietnam, 15 UH-1A Iroquois modified with armament systems capable of mounting machine guns and rockets.

In June 1962, Bell Helicopter presented a new helicopter design to Army officials, in the hopes of soliciting funding for further development. The D-255 Iroquois Warrior was envisioned as a purpose-built attack aircraft based on the UH-1B airframe and dynamic components, with a nose-mounted ball turret, a belly-mounted gun pod, and stub wings for mounting rockets or SS-10 anti-armor missiles.

Specifications (AH-56A)

General characteristics

• Crew: Two; one pilot, one copilot/gunner (front seat)
• Length: 54 ft 8 in (16.66 m)
• Rotor diameter: 51 ft 3 in (15.62 m)
• Height: 13 ft 8.5 in (4.18 m)
• Empty weight: 12,215 lb (5,540 kg)
• Loaded weight: 18,300 lb (8,300 kg)
• Max takeoff weight: 25,880 lb (11,740 kg)
• Powerplant: 1× General Electric T64-GE-16 turboshaft, 3,925 shp (2,930 kW)

Performance

• Maximum speed: 212 knots (244 mph, 393 km/h)
• Cruise speed: 195 kn (225 mph, 362 km/h)
• Range: 1,063 nmi (1,225 mi, 1,971 km)
• Service ceiling: 20,000 ft (6,100 m)
• Rate of climb: 3,000 ft/min (15.23 m/s)

Armament

• Guns:
  

1 × nose turret with either an M129 40 mm (1.57 in) grenade launcher or an XM196 7.62x51 mm machine gun and

1 × belly turret with an XM140 30 mm (1.18 in) cannon

• Hardpoints: 6
• Rockets: 2.75 in (70 mm) FFA rockets
• Missiles: BGM-71 TOW missiles