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Advanced Aerial Fire Support System

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Advanced Attack Helicopter (AAH)
Lockheed AH-56 Cheyenne.jpg
AH-56 Cheyenne during testing
Project for Attack helicopter
Issued by United States Army
Prototypes Bell D-262
Lockheed CL-840
Sikorsky S-66
Outcome CL-840 selected for production as Lockheed AH-56 Cheyenne
Successor programs Advanced Attack Helicopter

The Advanced Aerial Fire Support System (AAFSS)

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 evaluating industry proposals, the AAH competition was reduced to offerings from Bell and Hughes. Following a flight test evaluation of prototypes, Hughes' YAH-64 was selected in December 1976.[1]

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. Lockheed designed the Cheyenne using a four-blade rigid-rotor system and configured the aircraft as a compound helicopter with low-mounted wings and a tail-mounted thrusting propeller driven by a General Electric T64 turboshaft engine. The Cheyenne was to have a high-speed dash capability to provide armed escort for the Army's transport helicopters, such as the Bell UH-1 Iroquois.

In 1966, the Army awarded Lockheed a contract for ten AH-56 prototypes, but as a stopgap also ordered the less complex Bell AH-1G Cobra as an interim attack aircraft for combat in Vietnam War. The AH-56's maiden flight took place on 21 September 1967. In January 1968, the Army awarded Lockheed a production contract, based on flight testing progress. A fatal crash and technical problems affecting performance put Cheyenne development behind schedule, resulting in the cancellation of the production contract on 19 May 1969.[2] Development of the Cheyenne continued in the hope that the helicopter would eventually enter service.

As American involvement in Vietnam was winding down, the Army canceled the Cheyenne program on 9 August 1972. By this time, the AH-1 Cobra was widely deployed by the Army during the Vietnam War and equipped with the TOW anti-tank missile. Controversy with the United States Air Force over the Cheyenne's role in combat[3] as well as the political climate regarding military acquisition programs had caused the Army to amend the service's attack helicopter requirements in favor of a twin-engine conventional helicopter, viewed as less technical and more survivable.[4] The Army announced a new program for an Advanced Attack Helicopter (AAH) on 17 August 1972,[5] which led to the development of the Hughes AH-64 Apache.

Iroquois Warrior, Sioux Scout and AAFSS[edit]

Bell Model 207 Sioux Scout

Bell had been investigating helicopter gunships since the late 1950s, and had created a mockup of its D-255 helicopter gunship concept, named "Iroquois Warrior". In June 1962, Bell displayed the mockup to Army officials, hoping to solicit funding for further development. The Iroquois Warrior was planned to be a purpose-built attack aircraft based on UH-1B components with a new, slender airframe and a two-seat, tandem cockpit. It featured a grenade launcher in a ball turret on the nose, a 20 mm belly-mounted gun pod, and stub wings for mounting rockets or SS.10 anti-tank missiles.[6]

The Army was interested and awarded Bell a proof-of-concept contract in December 1962. Bell modified a Model 47 into the Model 207 Sioux Scout which first flew in July 1963. The Sioux Scout had all the key features of a modern attack helicopter: a tandem cockpit, stub wings for weapons, and a chin-mounted gun turret. After evaluating the Sioux Scout in early 1964, the Army was impressed, but also felt the Sioux Scout was undersized, underpowered, and generally not suited for practical use.[7][page needed]

The Army's solution to the shortcomings of the Sioux Scout was to launch the Advanced Aerial Fire Support System (AAFSS) competition.[7] The AAFSS requirement gave birth to the Lockheed AH-56 Cheyenne, a heavy attack helicopter with high speed capability. It proved to be too sophisticated, and was canceled in 1972, after ten years of development and replaced by the Advanced Attack Helicopter program. The Army sought greater survivability in a conventional attack helicopter.[7]

Background[edit]

During the mid-1960s, the United States Army initiated the Advanced Aerial Fire Support System (AAFSS) program, which led to the development of the Lockheed AH-56 Cheyenne for use in 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.[8][9] The main scenario used by NATO throughout the Cold War was that, if the Soviet Union and Warsaw Pact forces were to conduct a massive tank offensive attack on Western Europe, they would probably cross either the Fulda Gap (capturing Frankfurt first and then aiming for the westward bend of the Rhine south of Wiesbaden: a total distance of just 85 miles), or cross the North German Plain (see map). The Advanced Attack Helicopter was conceived from the need to defend against such an attack.

Background[edit]

The AH-1 Cobra was developed in the mid-1960s as an interim gunship for the U.S. Army for use in Vietnam. The Cobra shared the proven transmission, rotor system, and the T53 turboshaft engine of the UH-1 "Huey".[7]

By June 1967, the first AH-1G HueyCobras had been delivered. Originally designated as UH-1H, the "A" for attack designation was soon adopted and when the improved UH-1D became the UH-1H, the HueyCobra became the AH-1G.[7] Bell built 1,116 AH-1Gs for the US Army between 1967 and 1973, and the Cobras chalked up over a million operational hours in Vietnam.[7]

The US Army purchased the AH-1G as an "interim type" for the "jungle fighting" role, but the Army's broader concern was the task of protecting Western Europe from the legions of Warsaw Pact armor to the east.[10]

The Army had initiated the Advanced Aerial Fire Support System (AAFSS) program to develop the Lockheed AH-56 Cheyenne for the anti-tank gunship role, but development of the Cheyenne did not go smoothly, and as one writer put it, "the vultures began to gather", with Sikorsky and Bell trying to sell unsolicited alternatives to the Army. The Sikorsky offering was the S-67 Blackhawk, a sleek gunship, which despite the name was no real relation to the later S-70 Black Hawk utility-transport helicopter. The Bell offering was a refined HueyCobra, the Model 309 KingCobra.[10]

AAFSS and S-66 bid[edit]

The United States Army issued a request for proposals (RFP) for its Advanced Aerial Fire Support System (AAFSS) program on 1 August 1964.[11] Lockheed offered its CL-840 design, a rigid-rotor compound helicopter.[12] Sikorsky submitted the S-66, which featured a "Rotorprop" serving as a tail rotor but as speeds increased would rotate 90° to act as pusher prop.[13] The S-66 had short, fixed wings and was powered by a 3,400 shp (2,500 kW) Lycoming T55 turboshaft engine. The design was to have a speed of 200 knots (370 km/h) with the ability for 250 knots (460 km/h) for brief periods.[14]

The US Army awarded Lockheed and Sikorsky contracts for further study on 19 February 1965.[11] On 3 November 1965, the Army announced Lockheed as the winner of the AAFSS program selection. The Army perceived Lockheed's design as less expensive, able to be available earlier, and that it would have less technical risk than Sikorsky's Rotorprop.[11]

Development[edit]

Background[edit]

Prior to the development of the AH-56, all armed helicopters had been modifications to existing aircraft designed for unarmed uses.[15] In 1962, then U.S. Secretary of Defense Robert McNamara convened the Howze Board to review Army aviation requirements. The board recommended an airmobile division supported by 90 armed helicopters.[16] The recommendation of the Howze Board came at the same time the Army was preparing to deploy its first armed escort helicopters to Vietnam; 15 UH-1A Iroquois were modified with systems for mounting machine guns, grenade launchers, and rocket pods.[17]

In June 1962, Bell Helicopter presented a new helicopter design to Army officials, in the hopes of soliciting funding for further development. The D-255 Iroquois Warrior was envisioned as a purpose-built attack aircraft based on the UH-1B airframe and dynamic components, with a nose-mounted ball turret, a belly-mounted gun pod, and stub wings for mounting rockets or SS.10 anti-tank missiles.[18]

Attack helicopter requirements[edit]

In December 1962, Combat Development Command (CDC) drafted a Qualitative Material Requirement (QMR) for an interim, commercial off-the-shelf (COTS) aircraft, with a 140-knot (161 mph, 259 km/h) cruise speed and a 1,500-pound (680 kg) payload. This was seen as an attempt by Army officials, anticipating the potential of the D-255, to acquire an interim aircraft to fill the escort role until the Army could determine the requirements for a dedicated armed helicopter. However, the Secretary of the Army disapproved the interim approach and directed that the Army look for a more advanced system that would dramatically improve over current helicopter designs.[15]

Based on the guidance from the Secretary of the Army, CDC established Qualitative Material Development Objectives (QMDO) for a rotary-wing aircraft with 195-knot (224 mph, 361 km/h) cruise speed, 220-knot (253 mph, 407 km/h) dash speed, and the capability to hover out-of-ground-effect (OGE) at 6,000 feet (1,830 m) on a 95 °F (35 °C) day. The speed requirements were derived from the speed of aircraft the helicopter would escort. The Director of Defense Research and Engineering (DDRE) conditionally approved the changes to the development objectives, pending his review of the proposed program. He also directed the Army to determine whether or not any other helicopter could offer an improvement in performance over the UH-1B in the meantime.[19]

As a result, the Army Material Command (AMC) conducted a study to determine if the development objectives were feasible and also established a program office for the Fire-support Aerial System (FAS). AMC recommended to narrow the competition to compound helicopters, as they were considered the only helicopter configuration at the time capable of being developed to meet the objectives. In March 1964, the Secretary of the Army advised DDRE that modification of existing aircraft would not approach the required performance of the FAS program; the Army would continue using the armed UH-1B until development of the FAS could proceed.[19]

AAFSS competition[edit]

On 26 March 1964, the Army Chief of Staff redesignated the FAS program as the Advanced Aerial Fire Support System (AAFSS). The development objectives document (QMDO) for the AAFSS was approved in April 1964, and on 1 August 1964, the Transportation Research and Engineering Command contacted 148 prospective contractors with a request for proposals (RFP).[20] Bell submitted the D-262, a modification of the D-255, but still a conventional helicopter design. Sikorsky submitted the S-66, which featured a "Rotorprop" that would serve as a tail rotor but as speeds increased would rotate 90° to act as pusher propeller.[21] Lockheed submitted the CL-840 design, a rigid-rotor compound helicopter with both a pushing propeller and a conventional tail rotor mounted at the end of the tail.[12]

The Army announced Lockheed and Sikorsky as winners of Project Definition Phase contracts on 19 February 1965.[20] Meanwhile, the Army also continued to pursue an interim aircraft for combat in Vietnam until the AAFSS could be fielded, resulting in development of the Bell AH-1 Cobra which would become the backbone of the Army's attack helicopter fleet during and after the Vietnam War.[22]

Lockheed and Sikorsky developed proposals for their respective designs, establishing three configurations to satisfy both the development objectives and a revised RFP based on a draft requirements document. An evaluation board studied each company's proposal and then submitted its recommendation to a selection authority council on 6 October 1965. On 3 November 1965, the Army announced Lockheed as the winner of the AAFSS program. The Army perceived Lockheed's design as less expensive, able to be delivered sooner, and a lower technical risk than Sikorsky's Rotorprop. On 17 December 1965, the Army released the final requirements document. The document added fourteen requirements that were not previously addressed by Lockheed's proposal, including the addition of an aerial rocket armament subsystem.[23]

On 23 March 1966, the Army awarded Lockheed an engineering and development contract for 10 prototypes, designating the aircraft AH-56A. Initial operating capability was planned for 1972 with an optimistic target of late 1970. Lockheed began construction of the aircraft at its Van Nuys, California facility, and on 3 May 1967, Lockheed held a roll-out ceremony for the AH-56A. The aircraft was christened Cheyenne by the Army.[24] The first flight of the AH-56 occurred on 21 September 1967.[25] The Secretary of Defense approved pre-production funding to support an initial production order for 375 aircraft on 8 January 1968.[26][27] Manufacture of the 10 Cheyenne prototypes was completed by 1969.[28]

Program demise[edit]

In 1971, political friction increased between the Army and the Air Force over the close air support (CAS) mission.[29] The Air Force asserted that the Cheyenne would infringe on the Air Force's CAS mission in support of the Army, which had been mandated with the Key West Agreement of 1948.[30] The Department of Defense (DOD) conducted a study that concluded that the Air Force's A-X program, the Marine Corps' Harrier, and the Cheyenne were significantly different that they did not constitute a duplication of capabilities.[5] On 22 October 1971, the Senate Armed Services subcommittee on Tactical Air Power conducted hearings to evaluate the CAS mission and the pending programs. The most damaging testimony for the Army's program came from the commander of the Air Force's Tactical Air Command, General William W. Momyer, who cited helicopter casualty statistics of Operation Lam Son 719.[31]

The Army convened a special task force under General Marks in January 1972, to reevaluate the requirements for an attack helicopter. The purpose of the Marks Board was to develop an "updated and defensible" material needs document.[5] The task force conducted flight evaluations of the AH-56, along with two industry alternatives for comparison: the Bell 309 King Cobra and Sikorsky S-67 Blackhawk. Analysis of the three helicopters determined that the Bell and Sikorsky helicopters could not fulfill the Army's requirements.[5][18][32]

The Army also conducted a weapons demonstration for the Senate Armed Services Committee in early 1972, to show off the Cheyenne's firepower and garner support for attack helicopter development. The first TOW missile that was fired in the demonstration failed and went into the ground. The second missile was fired and hit the target. Previously, 130 TOW missiles had been fired without failure, but the failure of the first missile was now linked to perception of the aircraft.[33] In April 1972, the Senate published its report on CAS. The report recommended funding of the Air Force's A-X program, which would become the A-10 Thunderbolt II, and limited procurement of the Harrier for the Marine Corps. The report never referred to the Cheyenne by name and only offered a lukewarm recommendation for the Army to continue procurement of attack helicopters, so long as their survivability could be improved.[31]

The Cheyenne program was canceled by the Secretary of the Army on 9 August 1972.[5][34] The helicopter's large size and inadequate night/all-weather capability were reasons stated by the Army for the cancellation. The Cheyenne's analog and mechanical weapons systems were becoming out of date as new digital systems that were more accurate, faster, and lighter were being developed. The Cheyenne's unit cost had increased and was likely to increase further if new avionics were incorporated.[34][nb 1]

On 17 August 1972, the Army initiated the Advanced Attack Helicopter (AAH) program.[35] AAH sought an attack helicopter based on combat experience in Vietnam, with a lower top speed of 145 kn (167 mph, 269 km/h) and twin engines for improved survivability. Lockheed offered the CL-1700, a modified version of the Cheyenne with two engines and omitted the pusher propeller, without success.[36] The AAH program led to the AH-64 Apache, which entered service in the mid-1980s.

See also[edit]


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References[edit]

  1. Bishop, Chris. Apache AH-64 Boeing (McDonnell Douglas) 1976–2005. Osprey Publishing, 2005. ISBN 978-1-84176-816-8 Search this book on Amazon.com Logo.png..
  2. OAVCSA 1973, p. 7.
  3. Horwood, Ian. "Interservice Rivalry and Air Power in the Vietnam War" Archived 9 October 2011 at the Wayback Machine. Combat Studies Institute Press. pp. 131–134.
  4. Robb 2006, p. 47.
  5. 5.0 5.1 5.2 5.3 5.4 OAVCSA 1973, p. 9.
  6. Verier 1990, pp. 12–17.
  7. 7.0 7.1 7.2 7.3 7.4 7.5 Donald, David: Modern Battlefield Warplanes. AIRtime Publishing Inc, 2004. ISBN 1-880588-76-5 Search this book on Amazon.com Logo.png.
  8. First Generation Cobras, Vectorsite.net, 1 December 2008. Archived 7 August 2007 at the Wayback Machine
  9. Critical Technology Events in the Development of the Apache Helicopter
  10. 10.0 10.1 Goebel, Greg. Model 309 KingCobra / Model 409 AAH (YAH-63) Archived 2007-08-07 at the Wayback Machine. Vectorsite, 1 December 2008
  11. 11.0 11.1 11.2 Office of the Assistant Vice Chief of Staff of the Army (OAVCSA). An Abridged History of the Army Attack Helicopter Program, pp. 4–5, 9. Washington, DC: Department of the Army. 1973.
  12. 12.0 12.1 Landis and Jenkins 2000, pp. 25, 85–87.
  13. Apostolo 1984, p. 89.
  14. Landis and Jenkins 2000, p. 21.
  15. 15.0 15.1 OAVCSA 1973, p. 1.
  16. Bonin 1986, pp. 5–6.
  17. Wheeler, Howard A. Attack Helicopters, A History of Rotary-Wing Combat Aircraft, pp. 57–62, 64–65. The Nautical and Aviation Publishing Company, 1987. ISBN 0-933852-52-5 Search this book on Amazon.com Logo.png..
  18. 18.0 18.1 Verier, Mike. Bell AH-1 Cobra, pp. 12–17, 138. Osprey Publishing, 1990. ISBN 0-85045-934-6 Search this book on Amazon.com Logo.png..
  19. 19.0 19.1 OAVCSA 1973, pp. 1–2.
  20. 20.0 20.1 OAVCSA 1973, p. 4.
  21. Apostolo 1984, p. 89.
  22. OAVCSA 1973, p. 3.
  23. OAVCSA 1973, pp. 4–5.
  24. Landis and Jenkins 2000, pp. 35–36.
  25. Landis and Jenkins 2000, pp. 45, 97.
  26. OAVCSA 1973, p. 6.
  27. Landis and Jenkins 2000, p. 48.
  28. Landis and Jenkins 2000, p. 69.
  29. Campbell 2003, p. 84.
  30. Dahl 2003, p. 2.
  31. 31.0 31.1 Bonin 1986, pp. 32–33.
  32. Center of Military History. "Chapter V: Force Development". Dept. of the Army Historical Summary, 1972. Washington, D.C.: Headquarters, Department of the Army, 1972. Accessed 31 October 2008.
  33. Landis and Jenkins 2000, p. 81.
  34. 34.0 34.1 34.2 Landis and Jenkins 2000, pp. 79–82.
  35. OAVCSA 1973, p. 10.
  36. Landis and Jenkins 2000, pp. 81–82.

Notes[edit]

  1. U.S. Army reports state projected unit costs in $3.2–3.8 million range. Landis and Jenkins (2000) states a $3 million unit cost in 1972.[34]

Bibliography[edit]

External links[edit]

Category:Military aircraft procurement programs of the United States Category:Military helicopters


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