Back Lockheed AH-56 "Cheyenne"
1967

Lockheed AH-56 "Cheyenne"

The Lockheed AH-56 Cheyenne attack helicopter was created in response to the US Army's need for a fast, armoured and heavily armed helicopter to supplement the escort/attack role.

The Cheyenne featured a revolutionary compound helicopter configuration as well as a gyro-controlled rigid-rotor and three-bladed pusher tail propeller as well as a four-bladed anti-torque rotor. It had small wings attached to the side of the fuselage that could off-load the rotor during high speed flight. The helicopter was powered by a 4350shp General Electric T64-GE-16 gas turbine engine derated to 3925shp. The Cheyenne could accommodate a crew of two sitting in tandem in the enclosed cockpit with the gunner co-pilot in front of the pilot on a gun platform which could swivel 360°. A second gun system was housed in a nose turret. Six under-wing attachment points were used for missiles or rocket pods. The sophisticated weapon-sighting system included night-vision equipment and a helmet-gun sight.

The Cheyenne at first proved highly capable and in December 1967 the Army ordered a production batch of 375 Cheyennes. During further flight testing however there were three crashes. The helicopter proved unstable at high speeds in excess of 320km/h. After the third crash in 1969, when the main rotor collided with the fuselage, the production order was delayed. Further design modifications took place and by 1972 most of the Cheyennes' faults were cured but the program was cancelled due to budgetary problems. There were ten Cheyennes built.

Armed with a nose turret, with either a 7.62mm minigun or 30mm XM140 cannon, or a 40mm XM 129 grenade launcher, wing mounted TOW missiles or 2.75mm rocket pods, the Cheyenne could cruise at 388kmh with a max speed of 407km/h. It had a rate of climb in excess of 1025m/min and a range of 1970km.

P.Allen "The Helicopter", 1996

Lockheed AH-56 "Cheyenne"

The ambitious AH-56 Cheyenne helicopter, with which Lockheed hoped to establish a foothold in the rotary wing sector, was in fact a resounding failure for the Californian company. It featured a rigid main and tail rotor, which Lockheed had been researching since 1959 — a rigid rotor enables helicopters to perform genuine aerobatic manoeuvres.

The AH-56A Cheyenne was driven by a General Electric T64 turbine delivering over 3400shp. It had a stub wing with an 8m span and an area of 24m2, attachment points for six underwing stores weighing 900kg each, a streamlined fuselage with a tandem cabin seating arrangement, retractable front landing gear units, a fixed tailwheel, a rigid four-blade anti-torque tail rotor and three-blade pusher propeller at the tip of the tail boom. However the Cheyenne was technically too complicated and US Army orders were cancelled and development suspended in 1972.

G.Apostolo "The Illustrated Encyclopedia of Helicopters", 1984

Lockheed AH-56 "Cheyenne"

Developed as Lockheed's entry in the Army's Advanced Aerial Fire Support System (AAFSS) competition, the Cheyenne was a highly sophisticated compound rotorcraft whose design incorporated several features pioneered in Lockheed's earlier XH-51A. The Cheyenne was named winner of the AAFSS contest in March 1966, at which time Lockheed was awarded an Army contract for the production of ten YAH-56A prototypes. The first of these made its maiden flight in September 1967, and all ten aircraft (serials 66-8826 through -8835) had been delivered to the Army for flight testing by July 1968. In January of that year the Army had placed an initial order for 375 production machines, and the ten prototypes were subsequently redesignated AH-56A in early 1969.

The Cheyenne was, to say the least, a rather exotic-looking aircraft. The forward end of its long and narrow fuselage was dominated by an outsized segmented canopy covering a tandem, two-seat cockpit, while the tailboom supported a large ventral fin, a conventional anti-torque tail rotor, and a decidedly unconventional pusher propeller. A pair of small, low-set stub wings fixed to the fuselage sides contributed to the Cheyenne's hybrid look, as did its retractable, wheeled main landing gear. The AH-56A's ungainly appearance was deceptive, however, for in flight the craft was amazingly agile and extremely fast. The Cheyenne's impressive performance was the product of an innovative propulsion system built around a 3435shp General Electric shaft turbine engine. This powerplant drove a rigid, four-bladed, gyro-stabilized main rotor, the tail-mounted anti-torque rotor, and the pusher propeller at the extreme end of the tailboom. During vertical and hovering flight all power was applied to the main and anti-torque rotors, while during forward flight all but about 700shp was shafted to the pusher propeller. In forward flight lift was generated by the stub wings and windmilling main rotor, and in absolutely 'clean' configuration the AH-56A was capable of sea-level speeds in excess of 400kph.

The Army's AAFSS specifications had called for an aircraft capable of undertaking armed escort, long range interdiction, fire support, and anti-tank operations by day or night and in all weathers, and the Cheyenne had been armed and equipped accordingly. The AH-56A's armament consisted of a nose turret housing either an XM129 40mm automatic grenade launcher or XM134 7.62mm multi-barrelled minigun, a 30mm cannon mounted in a revolving belly turret, and an impressive number of TOW anti-tank missiles and/or pods of 2.75 inch unguided rockets carried on underwing hardpoints. The Cheyenne's day and night, all-weather flight capability was based on an extensive avionics suite which included automatic terrain-following radar, Doppler radar, an inertial navigation unit, and an automatic flight control system that allowed high-speed flight at altitudes as low as fifteen feet.

Despite its technological sophistication, or perhaps because of it, the AH-56A was fated never to enter regular Army service. The flight test programme revealed several significant problems with the aircraft's innovative propulsion system, problems which ultimately resulted in the fatal crash of one of the ten prototypes. In addition, by March 1979 significant cost overruns had increased the per-unit Cheyenne price by more than $500.000, an increase that was unacceptable in light of the Army's continued high expenditures in support of operations in Vietnam. And, finally, the USAF had become increasingly vocal in its opposition to the Army's acquisition of an aircraft as capable as the Cheyenne, and continued to push for the cancellation of the AH-56 project. The Army ultimately decided to develop a cheaper and less sophisicated helicopter in place of the Cheyenne, and in August 1972 formally terminated the AH-56 programme.

S.Harding "U.S.Army Aircraft since 1947", 1990

FACTS AND FIGURES

- Since the Cheyenne project, Lockheed has not put a military or civil helicopter into production.

- Power of the T64 engine was increased to 3,922hp during testing.

- Cancellation, in May 1969, came just six months before production began.

- In common with other US Army helicopters, the Cheyenne was named after a native American tribe.

- The highly manoeuvrable AH-56 was found to be a stable weapons platform.

- The other short-listed AAFSS prototype was the Sikorsky S-66.


Photo Gallery 

An AH-56A with underwing stores and a 30mm antitank cannon in a turret under the fuselage

Technical data for AH-56A "Cheyenne"

Crew: 2, engine: 1 x General Electric T64-GE-16 rated at 2580kW, main rotor diameter: 15.36m, length: 18.30m, height: 4.10m, take-off weight: 13600kg, empty weight: 5320kg, max speed: 408km/h

Comments1-20 21-40 41-60
Lukas Farber, e-mail, 30.07.2008reply

I have been doing some very extensive research on this airframe while at fort rucker for flight school. We are talking about 2.5 hours on station with 30 minutes transit time and a top speed of 240 knots (holy crap)I have not been to the "sandbox" yet however from what I understand this acft is exactly what we need over there. Once I get out of flight school I will try my hardest to get at least a test bed of one or two acft up and flying. I am going to contact Lockheed and see how much it would cost to get an updated model (touchscreen panels similiar to the Apache, fully digital fire control system, 4275 hp T64-GE-716 engine, AMCS, and all other final improvements made to the Cheyenne). There were a total of 11 cheyennes made (one static test article) 4 are still intact. If anyone can direct me to some people who can help restore the cheyenne to operational (in the process of contacting Dn Segner) or if you have experience in the field and can point out the Apache's shortcoming please email me at lukasfarber@hotmail.com (if you have an AKO account you can email me that way also)-Wo1 Luke, William M.

DODSWORTH, e-mail, 19.05.2008reply

This helicopter gunship of 1950's is very well designed.Truly cheyenne is great.

Migz, e-mail, 16.06.2008reply

I first saw this incredible machine as a kid my uncles house. He had cable and I was awe struck. I later found a hold helicopter book with it and it's specs I was impressed it was fast heavily armed. I feel if they had built it there would be no AH-64 the would have just upgraded the Cheyenne. Could you image it with 16 hellfire missiles and the fact that it could use it's 30mm cannon for heavy targets and a 7.62mm mini-gun for softer targets. To bad it didn't set any records due to symantecs aerodyne vs helio. I think the reason it was canceled had to do more with the Air Force crying foul for developing a helicopter that was too bad. As far number I'm not to sure how many were actually produced I know 1 crashed for sure. A 2nd may have to. I think 2 made it to a museum. 10 were suppose to be built for evaluation that means 2 down 2 in a museum but where are the other 6?

cocknuckle, e-mail, 31.03.2008reply

I agree with whiskers. I just returned from Afghanistan flying AH64D Longbones... and they were nearly useless. We had better technology in 1968!

Unkldave, e-mail, 07.02.2008reply

I flew one of these fine aircraft in 1978 from Fort Hood Tx to the airfield at Fort Eustis Va. where it was to be decommissioned and put into the museum on static display. That is not to say that I didn't have some fun on the flight over. Verrrrry fast and boy did that thing handle!It was very odd to have the main rotor so close overhead?

steve, e-mail, 22.05.2008reply

Another air force forced cancellation this when fully developed would have been the ultimate A H until the Apache and the Apache would be a better design

whiskers, e-mail, 30.12.2007reply

Yeah, this aircraft would have been perfect for the Afghanistan AO. We routinely flew behind 47s and 60s, all the time asking them to slow down since we couldn't keep up. But we keep on relying on the Air Force for CAS. Don't ask the Canucks how they feel about A-10s delivering CAS. They were too busy ducking for cover.

Charles Migot, e-mail, 14.12.2007reply

Where are the remaining 9 aircraft?

CannonFodder, 18.11.2007reply

Ummm...yeah, just look at the last line of the text.
"The Army ultimately decided to develop a cheaper and less sophisicated helicopter in place of the Cheyenne, and in August 1972 formally terminated the AH-56 programme."

Sgt.KAR98, 07.10.2007reply

Wasn´t?

"STINGRAY", e-mail, 26.11.2006reply

I THOUGHT THE PRODUCTION OF THIS HELICOPTER WAS CANCELED.

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