User:BillCJ/Sandbox/Advanced Attack Helicopter

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The Advanced Attack Helicopter was a United States Army program to develop an advanced ground attack helicopter. ...

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[edit] Background

During the mid-1960s, United States Army initiated the Advanced Aerial Fire Support System (AAFSS) program to develop the Lockheed AH-56 Cheyenne for the anti-tank gunship role. The US 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 legions of Warsaw Pact armor to the east.[1]

In 1972, the Army conducted an evaluation between the Bell Model 309 KingCobra, the Lockheed Cheyenne and Sikorsky S-67 in a competitive fly-off, beginning in the spring of 1972 and was completed in July. In August, somewhat to everyone's shock, the Army rejected all three.[1] Development difficulties resulted in the AH-56 Cheyenne being canceled later that year.

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. It would have the maneuverability to fly nap-of-the-earth (NoE) missions. To this end, the U.S. Army issued a request for proposals (RFP) for an Advanced Attack Helicopter (AAH) in 1972.[2]

[edit] Development

The U.S. Army issued a request for proposals (RFP) in 1972 for an Advanced Attack Helicopter (AAH). From an initial list of 5 manufacturers, Boeing-Vertol, Bell, Hughes, Lockheed, and Sikorsky, the finalists selected were Hughes Aircraft's Toolco Aircraft Division (later Hughes Helicopters) and Bell. Hughes' Model 77/YAH-64 was selected over Bell's Model 409/YAH-63 in 1976.

[edit] Bell 409

The simplest way to explain such a seemingly absurd result was that the Army's requirements had changed enough to require a serious rethinking of their helicopter gunship requirements, and the whole AAFSS program had become completely bogged down in politics anyway. The cancellation of AAFSS was immediately followed by the initiation of a new Advanced Attack Helicopter (AAH) program.[3]

The Army specified that the AAH was to be powered by twin General Electric T700 turboshaft engines with 1,120 kW (1,500 SHP) each, 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 TOW anti-tank missiles. The missile armament specification was later modified to include an alternate load of 16 laser-guided AGM-114 Hellfire anti-tank missiles. Hellfire was then in development and promised greater range and lethality than TOW.[3]

Boeing-Vertol, Bell, Hughes, Lockheed, and Sikorsky all submitted proposals for the AAH program. In June 1973, Bell and Hughes were selected as finalists, and were each awarded contracts for the construction of two prototype aircraft.[3]

The Bell entry, the Model 409 (YAH-63), was by no means "just another Cobra design", though it leveraged 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.[3]

Distinctive features included wheeled tricycle landing gear; flat canopy window plates; an unusual "tee" tail; a large ventral fin; and a three-barreled GE XM-188 30 millimeter cannon. One less noticeable feature was that the pilot occupied the front seat instead of the back, the reverse of the AH-1's arrangement. This was felt to be more prudent since the YAH-63 was intended to fly "in the treetops", or what is more formally called "nap of earth (NOE)" operations, and the pilot needed to have a clear view of the surroundings.[3]

The first prototype of the YAH-63 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, entered the flyoff against the Hughes entry, the Model 77 (YAH-64).[3]

The YAH-64 was selected in December 1976, and entered service as the AH-64 Apache. The Army felt the YAH-63's two-blade rotor was more vulnerable to damage than the Apache's four-bladed rotor, and the service didn't like the YAH-63's tricycle landing gear scheme, feeling it was less stable than the Apache's "taildragger" configuration. Some observers also suspected the Army didn't want to divert Bell from AH-1 production.[3]

[edit] Apache text

Following the cancellation of the AH-56 Cheyenne in favor of USAF and Marine projects like the A-10 and Harrier, the United States Army sought an aircraft to fill an anti-armor attack role that would still fall under Army command (the 1948 Key West Agreement having forbidden the Army from commanding fixed-wing aircraft). The Army wanted an aircraft better than the AH-1 Cobra in firepower, performance and range. It would have the maneuverability to fly nap-of-the-earth (NoE) missions. To this end, the US Army issued a Request For Proposals (RFP) for an Advanced Attack Helicopter (AAH) in 1972.[2]

Proposals were submitted by five manufacturers: Bell, Boeing-Vertol (teamed with Grumman), Hughes, Lockheed, and Sikorsky. In 1973, the U.S. Department of Defense selected finalists Bell and Hughes Aircraft's Toolco Aircraft Division (later Hughes Helicopters). This began the phase 1 of the competition.[2]

Each company built prototype helicopters and went through a flight test program. Hughes' Model 77/YAH-64A prototype first flew on September 30, 1975, while Bell's Model 409/YAH-63A prototype first flew the following day.[2] After evaluating test results, the Army selected Hughes' YAH-64A over Bell's YAH-63A in 1976. Reasons for selecting the YAH-64A included its more damage tolerant four-blade main rotor and the stability of the YAH-63's tricycle landing gear arrangement.[4]

The AH-64A then entered phase 2 of the AAH program. This called for building three preproduction AH-64s, and upgrading the two YAH-64A flight prototypes and the ground test unit up to the same standard.[5] Weapons and sensor systems were integrated and tested during this time,[2] including the new Hellfire missile.[5]


.[5]

In the 1960s, the US Army pinned its hopes for a front-line attack helicopter on the advanced Lockheed AH-56 Cheyenne gunship, adopting the less sophisticated Bell AH-1 HueyCobra as an interim solution until the Cheyenne became available. Like many interim solutions, the HueyCobra would remain in service for far longer than originally expected, since in the end the Cheyenne proved to not be quite the machine that the Army really wanted. It was a hefty, powerful "flying tank" that put a premium on raw speed and firepower at the expense of agility and treetop operation. The Army decided that a somewhat smaller and more maneuverable gunship would be more survivable.

The collapse of the Cheyenne program led the Army to issue a new request for proposals (RFP) for an "Advanced Attack Helicopter (AAH)" in August 1972. Five manufacturers submitted designs, and on 22 June 1973 the Bell "Model 409 /YAH-63" and the Hughes "Model 97 / YAH-64" were selected as finalists. Each contractor was to build two flight prototypes and a ground-test machine for evaluation.

Bell believed their YAH-63 was the front-runner because of the company's proven experience with the HueyCobra, and in fact their contender was basically a bigger and badder HueyCobra. The initial YAH-63 prototype performed its first flight on 1 October 1975, with the second machine flying on 21 December.

The first Hughes YAH-64 actually beat the first Bell prototype into the air by one day, performing its first flight on 30 September 1975. The second YAH-64 performed its initial flight on 22 November 1975. The Army put all four machines through an intensive test program. A separate competition was conducted for the sensor and targeting suite for the AAH, with Martin Marietta and Northrop submitting proposals in November 1976.

Late in the prototype evaluation, the Army threw Bell and Hughes a curve ball by changing the specification for the primary antitank weapon for the AAH from the proven TOW wire-guided missile to the new Hellfire laser-guided missile, with longer range and greater killing power than TOW. This was risky because Hellfire hadn't even been flown at the time, with the initial development contract with Rockwell International signed in October 1976.

In any case, the Hughes YAH-64 was declared as the winner on 10 December 1976. Both designs were regarded as very good, but the Hughes design seemed to have an edge in survivability. The "Phase 2" development program funded development of three preproduction "AH-64s", as well as bringing the two YAH-64 flight prototypes and the ground test machine up to the same specification.

The Phase 2 program suffered through a number of delays for various reasons and stretched out to over five years. First Phase 2 flight, of an upgraded initial prototype, was on 28 November 1977, with first flight of a new-build preproduction prototype on 31 October 1979. Initial Hellfire launches had already taken place by that time, with first firings in April 1979. A competitive evaluation of preproduction machines, one fitted with the Martin Marietta sensor / targeting suite and the other fitted with the Northrop suite, was performed, with Martin Marietta winning the competition in April 1980.

An initial production order for 11 "AH-64A Apache" attack helicopters was finally issued on 26 March 1982, with a follow-on order for 48 more machines delayed until the government and Hughes could work out some differences.

The first production machine was formally rolled out at the Hughes factory in Mesa, Arizona, on 30 September 1983. An Apache tribesman, in native dress and on horse with a Winchester rifle, helped honor the occasion, though embarrassingly the Hughes in-house newspaper failed to report his name while listing every other person of importance who attended.

Initial production hand-over to the US Army was on 26 January 1984, with the machine painted in dark green colors that would become standard for the Apache. By that time, the helicopter had become the "McDonnell Douglas (MDD) Apache" since MDD had bought out Hughes Helicopters in December 1983. MDD was bought out in turn by Boeing in the late 1990s, and so the machine is now the "Boeing Apache".

The AH-64A reached formal operational status with the US Army in July 1986, and went into service with the Army National Guard in 1989. The Army initially planned to buy 536 Apaches. Rising costs of the type ended up forcing cutbacks to 436 machines, but additional procurement eventually led to acquisition of 807 machines by 1994, not counting the six prototypes. A number of attrition replacement machines were also ordered, bringing the total of US Army production AH-64As to 821, with final deliveries in 1996.

[edit] References

  1. ^ a b First Generation Cobras, Greg Goebel's Vectorsite.
  2. ^ a b c d e Bishop, Chris. Apache AH-64 Boeing (McDonnell Douglas) 1976–2005. Osprey Publishing, 2005. ISBN 1-84176-816-2.
  3. ^ a b c d e f g Model 309 KingCobra / Model 409 AAH (YAH-63), Greg Goebel's Vectorsite.
  4. ^ Donald, David. Modern Battlefield Warplanes. AIRtime Publishing Inc, 2004. ISBN 1-880588-76-5.
  5. ^ a b c The Boeing AH-64 Apache, vectorsite.net, July 1, 2007.

The initial version of this article was based on a public domain article from Greg Goebel's Vectorsite.

[edit] External links

[edit] See also



Category:U.S. attack aircraft 1960-1969 Bell YAH-63 Category:Abandoned United States military projects

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