AH-56 Cheyenne

AH-56 Cheyenne
AH-56 Cheyenne during testing
TypeAttack helicopter
ManufacturerLockheed
Maiden flight21 September 1967
StatusCanceled
Number built10
Developed fromXH-51


The Lockheed AH-56 Cheyenne is a two-seat, single-engine compound helicopter with low-mounted, fixed wings and retractable landing gear. The AH-56 was designed in response to the perceived need for a fast heavily armed helicopter gunship. The compound design gave it a higher top speed and payload capacity than conventional designs. Although a successful design meeting the specifications was built, the project was canceled due to budget cuts.

Development

In the mid-1960s the U.S. Army concluded that a purpose-built gunship with more speed and firepower was required in the face of increasingly intense ground fire (often using heavy machine guns and anti-tank rockets) from Viet Cong and NVA troops. Based on this realization, and with the growing involvement in Vietnam, the U.S. Army developed the requirements for a dedicated attack helicopter, the "Advanced Aerial Fire Support System" (AAFSS). The aircraft would be able to cruise at 195 knots with dash speed of 220 kt. It would be able hover-out-of-ground effect (OGE) at 6,000 feet (PA) and 95 degrees F, and carry a much larger payload of weapons.[1]

In August 1964, the Army released its the request for proposals foe the AAFSS. In February 1965, Lockheed and Sikorsky were selected as finalists. In the end, Lockheed's design was announced the winner in November 1965 on the basis of the design being less expensive, available earlier, and having less technical risk. The quantitative requirements for the AAFSS were finally released by the Army on 17 December 1965, which included several changes including adding an aerial rocket subsystem. In all, fourteen requirements were added to what was in Lockheed's proposal.<ref name="Attack-1" />

An engineering development contract was signed by the Army and Lockheed in March 1966. Later in 1966, options for production were finalized and added to the contract. In January 1967, the Army ordered 375 aircraft in $31.4 million with an option for further aircraft provided validation of the AH-56's need.<ref name="Attack-1" />

A rigid rotor helicopter had been built by Lockheed as the XH-51 and the AH-56 followed in its path. Its first flight was on 21 September 1967. The project suffered a setback on 12 March 1969 when the rotor on one prototype hit the fuselage and killed the pilot. An order for 375 had been approved in 1968 but was canceled in 1969 as a result of budget cuts, and further development was halted in 1972.

The development of the new technologies on the AH-56 led to many cost and time overruns. This, coupled with Vietnam war experience and an adjustment in the Army's specification,[2] along with heavy campaigning by the Air Force which was in the midst of trying to get the A-10 authorized,[3] led to the Cheyenne's demise in favor of the AH-64 Apache, and continued production of AH-1 Cobra, which was quite successful in Vietnam, and would serve in USMC use beyond 2000. The Army would trade speed for survivability in the specification which would lead to the AH-64 Apache.

Cancellation

One of the 10 Cheyenne prototypes was lost in-flight while another was destroyed during wind tunnel testing. Eventually, the Army decided it wanted a smaller and lighter aircraft. The whole program was scrapped in 1972, and the US Army eventually adopted the AH-64 Apache.

Design

Enlarge picture
AH-56A Cheyenne at U.S. Army Aviation Museum, Ft. Rucker, AL, displaying the stub-wing, and both tail rotors.


The AH-56 Cheyenne is compound helicopter with a two-seat tandem cockpit, fixed low wings and retractable landing gear.

The Cheyenne has a short but substantial wing on each side of the airframe and a rigid main rotor. Thrust is provided by a pusher-prop at the rear of the aircraft. Since the main rotor is not relied on for the full amount of lift (provided by the wings) or thrust (from the pusher prop), the Cheyenne is able to reach high speeds - in excess of 200 kts. The design is classed as a compound helicopter, or gyrodyne, and is unable to qualify for speed records in helicopter categories. The Cheyenne also featured an advanced navigation and fire control suite which became the basis for the fire control suite in the AH-64 Apache.

An unusual feature of the AH-56 is the gunner's station. Like the AH-1 Cobra, the AH-56 has two crew members, seated in tandem—a pilot and a gunner. A turret with a 360° firing arc is located in the middle of aircraft underbelly, in contrast to the limited forward arc of the AH-1's chin turret. The AH-56 gunner's station, seat and consoles rotate along with the turret to keep the gunner facing the same direction as the guns, although the aircraft's design obscures approximately 120° of the gunner's rear view. The gun-sight affords the gunner direct viewing from the turret.

Specifications (AH-56A)

Data from Jane's Aircraft[4]

General characteristics

* Crew: 2 pilots: 1 pilot, 1 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)* Disc area: ft² (m²)* Empty weight: 12,215 lb (45,540 kg)* Loaded weight: 18,300 lb (8,300 kg)* Useful load: lb (kg)* Max takeoff weight: 25,880 lb (11,739 kg)*

Performance

Armament

Avionics

References

1. ^ Office of the Assistant Vice Chief of Staff of the Army (1973). "An Abridged History of the Army Attack Helicopter Program". Department of the Army.
2. ^ TOW MISSILE SYSTEM CHRONOLOGY 1961-2000 accessed 1 October 2007
3. ^ Landis & Jenkins "Warbird Tech Series, Volume 27", page 81. Specialty Press, 2000.
4. ^ (1969) in John W. R. Taylor: Jane's All the World's Aircraft, 1969-70. Sampson, Low, Marston & Co.. 

External links

Related content

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Comparable aircraft

Designation sequence

Related lists

See also

An attack helicopter is a military helicopter armed for attacking targets on the ground such as enemy infantry, armored vehicles and structures, using autocannon and machine-gun fire, rockets, and precision guided missiles such as the Hellfire.
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Lockheed Corporation (originally Loughead Aircraft Manufacturing Company) was an American aerospace company originally founded in 1912 which merged with Martin Marietta in 1995 to form Lockheed Martin.
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The maiden flight of an aircraft is the first occasion on which an aircraft leaves the ground of its own accord. This is similar to a ship's maiden voyage.

The first flight of a new aircraft type is always a historic occasion for the type.
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International Day of Peace
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  • RC Saints - Matthew the Evangelist
  • The Nativity of the Theotokos in Russia.
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  • 19th century - 20th century - 21st century
    1930s  1940s  1950s  - 1960s -  1970s  1980s  1990s
    1964 1965 1966 - 1967 - 1968 1969 1970

    Year 1967 (MCMLXVII
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    Lockheed XH-51 was an experimental helicopter design by Lockheed utilizing a rigid rotor. Lockheed's design, Model 186, was selected for a US military requirement for a high-speed, research helicopter.
    ..... Click the link for more information.
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    ..... Click the link for more information.
    Gyrodyne is a heavier-than-air aircraft with a rotor system that is normally driven by its engine for takeoff, hovering and landing like a helicopter, but which also has an additional propulsion system that is independent of the rotor system.
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    Ground effect is a generic term describing any aerodynamic effects occurring due to a vehicle's body or appendages moving in close proximity to the ground.
    Two main categories of ground effects exist:
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    Events


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    19th century - 20th century - 21st century
    1930s  1940s  1950s  - 1960s -  1970s  1980s  1990s
    1962 1963 1964 - 1965 - 1966 1967 1968

    Year 1965 (MCMLXV
    ..... Click the link for more information.
    Lockheed XH-51 was an experimental helicopter design by Lockheed utilizing a rigid rotor. Lockheed's design, Model 186, was selected for a US military requirement for a high-speed, research helicopter.
    ..... Click the link for more information.
    International Day of Peace
  • International Day against Alzheimer's disease
  • International Banana Festival
  • Day of the trees in Brazil
  • RC Saints - Matthew the Evangelist
  • The Nativity of the Theotokos in Russia.
    ..... Click the link for more information.
  • 19th century - 20th century - 21st century
    1930s  1940s  1950s  - 1960s -  1970s  1980s  1990s
    1964 1965 1966 - 1967 - 1968 1969 1970

    Year 1967 (MCMLXVII
    ..... Click the link for more information.
    March 12 is the 1st day of the year (2nd in leap years) in the Gregorian calendar. There are 0 days remaining.

    Events

    • 515 BC - Construction is completed on the Second Temple in Jerusalem.

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    19th century - 20th century - 21st century
    1930s  1940s  1950s  - 1960s -  1970s  1980s  1990s
    1966 1967 1968 - 1969 - 1970 1971 1972

    Also:
    *:1969 (number)
    *:

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    Total dead: ~314,000
    Total wounded: ~1,490,000
    North Vietnam and NLF
    dead and missing: ~1,100,000 [1] [2] [3] [4]
    wounded: ~600,000+ [5]
    People's Republic of China
    dead: 1,446
    wounded: 4,200

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    Manufacturer Hughes, McDonnell Douglas, Boeing IDS
    Maiden flight 30 September 1975
    Status Active service
    Primary users United States Army
    Israel Air Force
    Japan Ground Self-Defense Force
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    Type Attack helicopter
    Manufacturer Bell Helicopter Textron
    Maiden flight 1965-09-07
    Introduction 1967
    Status Active service
    Primary users United States Army
    Japan Self Defense Forces
    Pakistan Army
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    Manufacturer Hughes, McDonnell Douglas, Boeing IDS
    Maiden flight 30 September 1975
    Status Active service
    Primary users United States Army
    Israel Air Force
    Japan Ground Self-Defense Force
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    wind tunnel is a research tool developed to assist with studying the effects of air moving over or around solid objects.

    Ways that wind-speed and flow are measured in wind tunnels:

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