The Bell YAH-63 (Model 409) was an experimental
attack helicopter for the
Advanced Attack Helicopter
The Advanced Attack Helicopter (AAH) was a United States Army program to develop an advanced ground attack helicopter beginning in 1972. The Advanced Attack Helicopter program followed cancellation of the Lockheed AH-56 Cheyenne. After evalua ...
(AAH) competition. Hughes' ''Model 77/YAH-64'', later developed into the
AH-64 Apache
The Boeing AH-64 Apache () is an American twin- turboshaft attack helicopter with a tailwheel-type landing gear arrangement and a tandem cockpit for a crew of two. It features a nose-mounted sensor suite for target acquisition and night v ...
, was selected over Bell's entry.
Design and development
Background
During the mid-1960s,
United States Army
The United States Army (USA) is the land warfare, land military branch, service branch of the United States Armed Forces. It is one of the eight Uniformed services of the United States, U.S. uniformed services, and is designated as the Army o ...
initiated the Advanced Aerial Fire Support System (AAFSS) program to develop the
Lockheed AH-56 Cheyenne
The Lockheed AH-56 Cheyenne was an attack helicopter developed by Lockheed for the United States Army. It rose from the Army's Advanced Aerial Fire Support System (AAFSS) program to field the service's first dedicated attack helicopter. Lock ...
for the anti-tank gunship role. The U.S. Army pursued the
AH-1G HueyCobra as an interim type for the "jungle fighting" role. However the Army's broader concern was the task of protecting Western Europe from the numerous Warsaw Pact tanks to the east.
[Greg Goebel]
First Generation Cobras
. Vectorsite, 1 December 2008.
In 1972, the Army conducted an evaluation between the
Bell 309 KingCobra
The Bell Model 309 KingCobra was an experimental attack helicopter developed by Bell Helicopter, based on the Bell AH-1 Cobra.
Design and development
Background
The AH-1 Cobra was developed in the mid-1960s as an interim gunship for the U.S. A ...
, the Lockheed Cheyenne, and the
Sikorsky S-67
The Sikorsky S-67 Blackhawk was a private-venture, prototype attack helicopter built in 1970 with Sikorsky Aircraft research and development (R&D) funds. A tandem, two-seat aircraft designed around the dynamic drive and rotor systems of the Si ...
in a competitive fly-off. The fly-off began in the spring 1972 and was completed in July. In August, somewhat to everyone's shock, the Army rejected all three competitors.
[Greg Goebel]
Model 309 Kingcobra / Model 409 AAH (YAH-63)
. Vectorsite, 1 December 2008.
Difficulties delayed the AH-56 Cheyenne development. The Army canceled the Cheyenne program in August 1972. Controversy over the Cheyenne's role in combat and the political climate regarding military acquisition programs caused the Army to amend the service's attack helicopter requirements in favor of a simpler and more survivable conventional helicopter.
[Robb, Raymond L]
"Hybrid helicopters: Compounding the quest for speed"
''Vertiflite''. Summer 2006. American Helicopter Society.[
]
Advanced Attack Helicopter
The Army sought an aircraft to fill an anti-armor attack role. The Army wanted an aircraft better than the AH-1 Cobra in firepower, performance and range. The aircraft would have the maneuverability to fly nap-of-the-earth
Nap-of-the-earth (NOE) is a type of very low-altitude flight course used by military aircraft to avoid enemy detection and attack in a high-threat environment. Other, mostly older terms include "ground-hugging", "terrain masking", "flying under t ...
(NoE) missions. To this end, the U.S. Army issued a request for proposals (RFP) for an Advanced Attack Helicopter
The Advanced Attack Helicopter (AAH) was a United States Army program to develop an advanced ground attack helicopter beginning in 1972. The Advanced Attack Helicopter program followed cancellation of the Lockheed AH-56 Cheyenne. After evalua ...
(AAH) in 1972.[Office of the Assistant Vice Chief of Staff of the Army (OAVCSA)]
''An Abridged History of the Army Attack Helicopter Program''
Washington, DC: Department of the Army, 1973.[Bishop, Chris. ''Apache AH-64 Boeing (McDonnell Douglas) 1976–2005''. Osprey Publishing, 2005. .]
The Army specified that the AAH was to be powered by twin General Electric T700 turboshaft engines with 1,500 shp (1,120 kW) each. This was the same powerplant fit specified for a new Army utility helicopter competition that would be won by the Sikorsky S-70 Black Hawk. The AAH would be armed with a 30 millimeter cannon and sixteen BGM-71 TOW
The BGM-71 TOW ("Tube-launched, Optically tracked, Wire-guided") is an American anti-tank missile. TOW replaced much smaller missiles like the SS.10 and ENTAC, offering roughly twice the effective range, a more powerful warhead, and a greatly ...
anti-tank missiles. The missile armament specification was later modified to include an alternate load of sixteen laser-guided AGM-114 Hellfire anti-tank missiles. Hellfire was then in development and promised greater range and lethality than TOW.[
]Bell
A bell is a directly struck idiophone percussion instrument. Most bells have the shape of a hollow cup that when struck vibrates in a single strong strike tone, with its sides forming an efficient resonator. The strike may be made by an inte ...
, Boeing-Vertol (teamed with Grumman
The Grumman Aircraft Engineering Corporation, later Grumman Aerospace Corporation, was a 20th century American producer of military and civilian aircraft. Founded on December 6, 1929, by Leroy Grumman and his business partners, it merged in 1994 ...
), Hughes
Hughes may refer to:
People
* Hughes (surname)
* Hughes (given name)
Places Antarctica
* Hughes Range (Antarctica), Ross Dependency
* Mount Hughes, Oates Land
* Hughes Basin, Oates Land
* Hughes Bay, Graham Land
* Hughes Bluff, Victoria La ...
, Lockheed, and Sikorsky all submitted proposals for the AAH program. In June 1973, Bell and Hughes were selected as finalists, and each was awarded a contract for the construction of two prototype aircraft.[Bishop, Chris. ''Huey Cobra Gunships''. Osprey Publishing, 2006. .]
The Bell entry, the Model 409 (YAH-63), was by no means "just another Cobra design" though it utilized Cobra technology where possible. Although it had what had become by then the typical configuration for a helicopter gunship, with a sharklike fuselage, tandem crew seating, and stub wings for armament, the YAH-63 was largely a new machine.[
Distinctive features included wheeled ]tricycle landing gear
Tricycle gear is a type of aircraft undercarriage, or ''landing gear'', arranged in a tricycle fashion. The tricycle arrangement has a single nose wheel in the front, and two or more main wheels slightly aft of the center of gravity. Tricycle g ...
, flat canopy window plates, an unusual "tee" tail, a large ventral fin, and a three-barreled General Electric XM-188 cannon. The YAH-63's rotor mast could be lowered and the landing gear could kneel to reduce its height for transport.[Verier 1990, p. 142.] One less noticeable feature was that the pilot occupied the front seat instead of the rear, the reverse of the AH-1's arrangement. This was believed to be more prudent since the YAH-63 was intended to fly "in the treetops" during "nap-of-the-earth
Nap-of-the-earth (NOE) is a type of very low-altitude flight course used by military aircraft to avoid enemy detection and attack in a high-threat environment. Other, mostly older terms include "ground-hugging", "terrain masking", "flying under t ...
" (NoE) operations, and the pilot needed to have a clear view of the aircraft's surroundings.[
The first prototype of the YAH-63 (serial 73-22246)][Pike, John]
YAH-63
GlobalSecurity.org, 12 January 2008. made its initial flight on 1 October 1975. This rotorcraft crashed in June 1976 but a static test prototype was brought up to flight standard and, along with the second prototype (73-22247), entered the flyoff against the Hughes entry, the Model 77 (YAH-64).[
The Hughes YAH-64 was selected in December 1976 and was developed into the production ]AH-64 Apache
The Boeing AH-64 Apache () is an American twin- turboshaft attack helicopter with a tailwheel-type landing gear arrangement and a tandem cockpit for a crew of two. It features a nose-mounted sensor suite for target acquisition and night v ...
version. The Army believed that the YAH-63's two-blade rotor was more vulnerable to damage than the Apache's four-bladed rotor. In addition the service did not like the YAH-63's tricycle landing gear scheme, believing it was less stable than the Apache's "taildragger
Conventional landing gear, or tailwheel-type landing gear, is an aircraft undercarriage consisting of two main wheels forward of the center of gravity and a small wheel or skid to support the tail.Crane, Dale: ''Dictionary of Aeronautical Term ...
" configuration. Some observers also suspected that the Army did not want to divert Bell from AH-1 production.[ Bell would use its experience with the T700 engine to develop the AH-1T+ design and later ]AH-1W
The Bell AH-1 SuperCobra is a twin-engined attack helicopter that was developed on behalf of, and primarily operated by, the United States Marine Corps (USMC). The twin Cobra family, itself part of the larger Huey family, includes the AH-1J Se ...
.[Verier 1990, pp. 143-144.]
Operators
;
* United States Army
The United States Army (USA) is the land warfare, land military branch, service branch of the United States Armed Forces. It is one of the eight Uniformed services of the United States, U.S. uniformed services, and is designated as the Army o ...
(evaluation only)
Specifications (YAH-63)
See also
References
* Verier, Mike. ''Bell AH-1 Cobra''. Osprey Publishing, 1990. .
External links
YAH-63 Helicopter Crashworthiness Simulation and Analysis
U.S. Army, February 1983.
{{USAF helicopters
Bell AH-63
Bell YAH-63
The Bell YAH-63 (Model 409) was an experimental attack helicopter for the Advanced Attack Helicopter (AAH) competition. Hughes' ''Model 77/YAH-64'', later developed into the AH-64 Apache, was selected over Bell's entry.
Design and development B ...
H-063, A
1970s United States helicopters
Twin-turbine helicopters
Attack helicopters
Aircraft first flown in 1975