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AH-56A Cheyenne - Design

The Cheyenne had one engine, an anti-torque rotor, small wings, a pusher-propeller, and a rigid main rotor. During high-speed forward flight, the wings and pusher-propeller provide most of the lift and forward propulsion, respectively. The rigid rotor system was not used to any great extent for lift at high speeds but serves to provide flight control stability and maneuverability.

The aircraft had tandem cockpits, (The copilot-gunner was in front.) It had some armor to protect critical components against small projectiles, had self-sealing fuel tanks, and redundant pilot controls. It was 60 feet long (55 feet when main rotor blades are folded) and 14 feet high and had a wingspan of 27 feet and an empty weight of 12,215 pounds. Variations in atmospheric conditions and the weight of fuel and ordnance affect the performance of any combat aircraft. Under standard day conditions (59O F. at sea level), the Army expects the Cheyenne to be capable of vertically lifting about 12,000 pounds of fuel, ordnance, and weapon pods. If the Cheyenne was given a few hundred feet of runway for a short takeoff, its payload can be expected to increase slightly. The aircraft's maximum internal fuel load was 2,861 pounds.

The Cheyenne's maximum dash speed was expected to be about 245 miles an hour, and its maximum cruise speed was expected to be about 225 miles an hour, although these speeds would decrease with heavy payloads. The Cheyenne was capable, as are more conventional helicopters, of hovering and of sideward and rearward flight. These flight characteristics, coupled with its low speed, permit nap-of- the- earth flight (just clearing ground vegetation) and allow the aircraft to operate in inclement weather with visibility and ceilings that are not negotiable by fixed-wing aircraft.

The Cheyenne had gun turrets in its nose and belly and six hardpoint stations on its wings and belly to carry rockets and missiles. Its missile guidance equipment was built in. In the nose turret was a 7.62 mm antipersonnel minigun with a selectable rate of fire of 750 to 6,000 shots a minute. Interchangeable with that was a 40 mm grenade launcher that fires 350 shots a minute against personnel and light armor. Either weapon may be (1) traversed 120' to the right or left of the aircraft's nose, (2) lowered 60' or (3) raised 18'. Mounted on the belly turret was a 30 mm automatic cannon that fires 405 shots a minute to an effective range of about 10,000 feet. It would be used against personnel and light armor and can be fired in any direction; it can be lowered 70 and raised 18'.

The wing stations would accommodate up to 152 rockets (2.75 in.) or 36 tube-launched, optically tracked, wireguided (TOW) missiles. The rockets are forward firing and are used for area fire suppression, and the TOW missile was to be used against heavy armor. Although only one missile can be fired and guided at a time, the aircraft may take evasive action once a missile was locked onto the target. An evaluation by U.S. Army, Europe, in the European environment showed that a scout-aircraft pilot needed an observer to acquire a target, since the pilot could not simultaneously acquire a target and perform the many other tasks required of him. This may indicate that the Cheyenne pilot may be too involved in flying the aircraft (maneuvering, etc.) to provide effective suppressive fire while the copilot was firing the TOW. The Cheyenne's fire control system and the pilot's helmet sight, however, which were not available during the European evaluation, may enhance the pilot's ability to deliver suppressive fire.

The Cheyenne had fully integrated and highly sophisticated avionics. Its communication equipment, for instance, was designed to provide coordination with supported ground units, communication with other aircraft, and air traffic control. There are a self-contained navigation system and other navigational aids to help provide continuous operation in the forward combat area.

The fire control system permits the pilot and copilot gunner to fire all weapons, but only the copilot can fire the TOW missile. The pilot and gunner, though, can fire simultaneously at different targets. The gunner had a direct sight and a magnifying periscope sight. The two sights and the gunner's seat are mounted together on a 360 swiveling gunner's station. The lower sight assembly of the station extends out the bottom of the fuselage and contains the telescopic optics, a laser range finder, and the TOW missile guidance equipment. By activating the control for the swiveling gunner's station, the gunner may change his view to any direction.

The pilot can use a direct sight or his helmet sight at will; the turreted weapons are slaved to the helmet sight, so that they turn automatically as the pilot turns his head. A computer manages the fire control system: as the pilot changes his sight direction the computer automatically transmits corrective commands to the turreted weapons to achieve accuracy. The computer was expected to be capable of storing data about several target positions for subsequent attack and of incorporating a thermal-imaging (heat silhouette) night-vision system for fighting in darkness and poor visibility. The night vision system enhances visibility through smoke, haze, and fog.

It should be noted that the Army expected the Cheyenne to offer increased capabilities over the UH-1B helicopter which was used in the RAC studies. The survivability of the Cheyenne, the Army believed would be enhanced by the aircraft's:

  1. Greater speed and maneuverability.
  2. Additional protective armor.
  3. 360' weapon-firing capability.
  4. Greater weapon load and accuracy through computerized fire control.
  5. Self-contained navigation system.
  6. Night-vision system.
  7. Podded electronic counter measure devices.
  8. Improved target-acquisition equipment.



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Page last modified: 15-02-2014 17:32:55 ZULU