My dad told me a lot of story about this helicopter. anyway here some info on it.

Lockheed AH-56 Cheyenne

From Wikipedia, the free encyclopedia

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 T64 turboshaft 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.[1] Cheyenne development continued in the hope that the helicopter would eventually enter service. In 1966 the Army ordered the simpler AH-1G Cobra as an interim attack aircraft for combat in Vietnam.

But as American involvement in Vietnam was winding down the Army canceled the Cheyenne program on 9 August 1972. 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.[2] The Army announced a new program for an Advanced Attack Helicopter on 17 August 1972.[3] This lead to the successful AH-64 Apache attack helicopter, a conventional helicopter emphasizing armor protection, armed with laser-guided missiles and cannon.