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{|{{Infobox aircraft begin
 |name = Advanced Aerial Fire Support System (AAFSS)
 |image= File:Lockheed AH-56 Cheyenne.jpg
 |caption= AH-56 Cheyenne during testing
}}{{Infobox aircraft program
 |aim = [[Attack helicopter]]
 |requirement =
 |issuer = [[United States Army]]
 |service =
 |value =
 |initiated =
 |proposals =
 |prototypes = [[Bell D-262]] <br/> [[Lockheed AH-56 Cheyenne|Lockheed CL-840]] <br/> [[Sikorsky S-66]]
 |concluded =
 |outcome = CL-840 selected for production as Lockheed AH-56 Cheyenne
 |predecessors = 
 |successors = [[Advanced Attack Helicopter]]
 |related =
}}
|}

The '''Advanced Aerial Fire Support System''' ('''AAFSS''') was a United States Army program to develop the service's first dedicated 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 evaluating industry proposals, the AAH competition was reduced to offerings from [[Bell Helicopter|Bell]] and [[Hughes Helicopters|Hughes]]. Following a flight test evaluation of prototypes, Hughes' [[Boeing AH-64 Apache|YAH-64]] was selected in December 1976.<ref name="Bishop_AH-64">Bishop, Chris. ''Apache AH-64 Boeing (McDonnell Douglas) 1976–2005''. Osprey Publishing, 2005. {{ISBN|978-1-84176-816-8}}.</ref>

The '''Lockheed AH-56 Cheyenne''' was an attack helicopter developed by [[Lockheed Corporation|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 [[Helicopter rotor#Rigid|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-1 Cobra|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.<ref name=Army_p7>OAVCSA 1973, p. 7.</ref> 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 [[BGM-71 TOW|TOW]] anti-tank missile. Controversy with the [[United States Air Force]] over the Cheyenne's role in combat<ref name=Rivalry>Horwood, Ian. [http://carl.army.mil/download/csipubs/horwood.pdf "Interservice Rivalry and Air Power in the Vietnam War"] {{Webarchive|url=https://web.archive.org/web/20111009064121/http://carl.army.mil/download/csipubs/horwood.pdf |date=9 October 2011 }}. Combat Studies Institute Press. pp. 131–134.</ref> 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.<ref name=Robb_p47>Robb 2006, p. 47.</ref> The Army announced a new program for an Advanced Attack Helicopter (AAH) on 17 August 1972,<ref name=Army_p9>OAVCSA 1973, p. 9.</ref> which led to the development of the Hughes AH-64 Apache.

====Iroquois Warrior, Sioux Scout and AAFSS====
[[File:Bell 207.jpg|thumb|Bell Model 207 Sioux Scout]]
{{main|Bell 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&nbsp;mm belly-mounted gun pod, and stub wings for mounting rockets or [[SS.10]] anti-tank missiles.<ref name=Verier_p12-7>Verier 1990, pp. 12–17.</ref>

The Army was interested and awarded Bell a proof-of-concept contract in December 1962. Bell modified a [[Bell 47|Model 47]] into the [[Bell 207 Sioux Scout|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 (aviation)|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.<ref name=Donald/>{{page needed|date=January 2021}}

The Army's solution to the shortcomings of the Sioux Scout was to launch the [[Advanced Aerial Fire Support System]] (AAFSS) competition.<ref name=Donald/> 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.<ref name=Donald/>

==Background==

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.<ref name="Vectorsite_Cobras">[http://www.vectorsite.net/avcobra_1.html First Generation Cobras], Vectorsite.net, 1 December 2008. {{webarchive |url=https://web.archive.org/web/20070807001809/http://www.vectorsite.net/avcobra_1.html |date=7 August 2007 }}</ref><ref>[http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA450121&Location=U2&doc=GetTRDoc.pdf Critical Technology Events in the Development of the Apache Helicopter]</ref> 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-am-Main|Frankfurt]] first and then aiming for the westward bend of the [[Rhine]] south of [[Wiesbaden]]: a total distance of just 85&nbsp;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===
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".<ref name="Donald">Donald, David: ''Modern Battlefield Warplanes''. AIRtime Publishing Inc, 2004. {{ISBN|1-880588-76-5}}</ref>

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.<ref name="Donald"/>  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.<ref name="Donald"/>

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.<ref name="Vectorsite">Goebel, Greg. [http://www.vectorsite.net/avcobra_1.html#m4 Model 309 KingCobra / Model 409 AAH (YAH-63)] {{webarchive|url=https://web.archive.org/web/20070807001809/http://www.vectorsite.net/avcobra_1.html |date=2007-08-07 }}. Vectorsite, 1 December 2008</ref>

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 [[Sikorsky S-67 Blackhawk|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.<ref name="Vectorsite"/>

===AAFSS and S-66 bid===
The United States Army issued a request for proposals (RFP) for its Advanced Aerial Fire Support System (AAFSS) program on 1 August 1964.<ref name=Army_AAH>Office of the Assistant Vice Chief of Staff of the Army (OAVCSA). [https://www.webcitation.org/5JNGWqTeh?url=http://cgsc.cdmhost.com/cdm4/item_viewer.php?CISOROOT=%2Fp4013coll11 ''An Abridged History of the Army Attack Helicopter Program''], pp. 4–5, 9. Washington, DC: Department of the Army. 1973.</ref> Lockheed offered its CL-840 design, a rigid-rotor compound helicopter.<ref name=Landis_p25>Landis and Jenkins 2000, pp. 25, 85–87.</ref>  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.<ref name=Apostolo_p89>Apostolo 1984, p. 89.</ref> The S-66 had short, fixed wings and was powered by a {{convert|3400|shp|kW|abbr=on|sigfig=2}} [[Lycoming T55]] turboshaft engine.  The design was to have a speed of {{convert|200|kn|km/h|sigfig=2}} with the ability for {{convert|250|kn|km/h|sigfig=2}} for brief periods.<ref name=Landis_p21>Landis and Jenkins 2000, p. 21.</ref>

The US Army awarded Lockheed and Sikorsky contracts for further study on 19 February 1965.<ref name=Army_AAH/>  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.<ref name=Army_AAH/>

==Development==

===Background===
Prior to the development of the AH-56, all armed helicopters had been modifications to existing aircraft designed for unarmed uses.<ref name=Army_p1>OAVCSA 1973, p. 1.</ref> In 1962, then [[United States Secretary of Defense|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.<ref>Bonin 1986, pp. 5–6.</ref> 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.<ref>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}}.</ref>

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 missile]]s.<ref name=Verier_p12-17_138>Verier, Mike. ''Bell AH-1 Cobra'', pp. 12–17, 138. Osprey Publishing, 1990. {{ISBN|0-85045-934-6}}.</ref>

===Attack helicopter requirements===
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&nbsp;mph, 259&nbsp;km/h) cruise speed and a 1,500-pound (680&nbsp;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 [[United States Secretary of the Army|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.<ref name=Army_p1/>

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&nbsp;mph, 361&nbsp;km/h) cruise speed, 220-knot (253&nbsp;mph, 407&nbsp;km/h) dash speed, and the capability to [[Ground effect in aircraft#Wing in ground effect and helicopters|hover out-of-ground-effect]] (OGE) at 6,000&nbsp;feet (1,830&nbsp;m) on a 95&nbsp;°F (35&nbsp;°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.<ref name=Army_p1-2>OAVCSA 1973, pp. 1–2.</ref>

As a result, the [[United States Army Materiel Command|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.<ref name=Army_p1-2/>

===AAFSS competition===
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 [[Aviation Applied Technology Directorate|Transportation Research and Engineering Command]] contacted 148 prospective contractors with a request for proposals (RFP).<ref name=Army_p4>OAVCSA 1973, p. 4.</ref> Bell submitted the D-262, a modification of the D-255, but still a conventional helicopter design. Sikorsky submitted the [[Sikorsky S-67#AAFSS and S-66 bid|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.<ref name=Apostolo>Apostolo 1984, p. 89.</ref> 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.<ref name=Landis_p25>Landis and Jenkins 2000, pp. 25, 85–87.</ref>

The Army announced Lockheed and Sikorsky as winners of Project Definition Phase contracts on 19 February 1965.<ref name=Army_p4/> 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.<ref name=Army_p3>OAVCSA 1973, p. 3.</ref>

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.<ref name=Army_p4-5>OAVCSA 1973, pp. 4–5.</ref>

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.<ref name=Landis_p35-36>Landis and Jenkins 2000, pp. 35–36.</ref> The first flight of the AH-56 occurred on 21 September 1967.<ref name=Landis_p45_97>Landis and Jenkins 2000, pp. 45, 97.</ref> The Secretary of Defense approved pre-production funding to support an initial production order for 375 aircraft on 8 January 1968.<ref name=Army_p6>OAVCSA 1973, p. 6.</ref><ref name=Landis_p48>Landis and Jenkins 2000, p. 48.</ref> Manufacture of the 10 Cheyenne prototypes was completed by 1969.<ref name=Landis_p69>Landis and Jenkins 2000, p. 69.</ref>

===Program demise===
In 1971, political friction increased between the Army and the Air Force over the close air support (CAS) mission.<ref name=Campbell_p84>Campbell 2003, p. 84.</ref> 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.<ref name=Dahl_p2>Dahl 2003, p. 2.</ref> The Department of Defense (DOD) conducted a study that concluded that the Air Force's A-X program, the Marine Corps' [[Hawker Siddeley Harrier|Harrier]], and the Cheyenne were significantly different that they did not constitute a duplication of capabilities.<ref name=Army_p9/> 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]].<ref name=Bonin_p32-3>Bonin 1986, pp. 32–33.</ref>

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.<ref name=Army_p9/> 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.<ref name=Army_p9/><ref name=Verier_p12-17_138/><ref name=DAHSUM_1972>Center of Military History. [http://www.history.army.mil/books/DAHSUM/1972/ch05.htm#b6 "Chapter V: Force Development"] {{Webarchive|url=https://web.archive.org/web/20170101044225/http://www.history.army.mil/books/DAHSUM/1972/ch05.htm#b6 |date=1 January 2017 }}. ''Dept. of the Army Historical Summary, 1972''. Washington, D.C.: Headquarters, Department of the Army, 1972. Accessed 31 October 2008.</ref>

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.<ref name=Landis_p81>Landis and Jenkins 2000, p. 81.</ref> 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 [[Fairchild Republic A-10 Thunderbolt II|A-10 Thunderbolt II]], and limited procurement of the Harrier for the [[United States Marine Corps|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.<ref name=Bonin_p32-3/>

The Cheyenne program was canceled by the Secretary of the Army on 9 August 1972.<ref name=Army_p9/><ref name=Landis_p79-82>Landis and Jenkins 2000, pp. 79–82.</ref> 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.<ref name=Landis_p79-82/>{{refn|U.S. Army reports state projected unit costs in $3.2–3.8&nbsp;million range. Landis and Jenkins (2000) states a $3&nbsp;million unit cost in 1972.<ref name=Landis_p79-82/>|group=nb}}

On 17 August 1972, the Army initiated the Advanced Attack Helicopter (AAH) program.<ref name=Army_p10>OAVCSA 1973, p. 10.</ref> AAH sought an attack helicopter based on combat experience in Vietnam, with a lower top speed of 145&nbsp;kn (167&nbsp;mph, 269&nbsp;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.<ref name=Landis_p81-82>Landis and Jenkins 2000, pp. 81–82.</ref> The AAH program led to the [[AH-64 Apache]], which entered service in the mid-1980s.

==See also==
{{Portal|Aviation}}
* [[List of attack aircraft]]
* [[List of military aircraft of the United States]]
* [[List of rotorcraft]]

==References==
{{reflist}}

===Notes===
{{reflist|group=nb}}

===Bibliography===
* Donald, David. "AH-64A/D Apache and AH-64D Longbow Apache", ''Modern Battlefield Warplanes''. AIRtime Publishing Inc, 2004. {{ISBN|978-1-880588-76-5}}.
* Government Accounting Office. [http://archive.gao.gov/f0202/092647.pdf ''Staff Study: Advanced Attack Helicopter'']. Washington, D.C.: US Government Accounting Office, 1974.
* Landis, Tony and Jenkins, Dennis R. ''Lockheed AH-56A Cheyenne – WarbirdTech Volume 27''. Specialty Press, 2000. {{ISBN|978-1-58007-027-0}}.
* Office of the Assistant Vice Chief of Staff of the Army (OAVCSA). [https://web.archive.org/web/20060712135303/http://cgsc.cdmhost.com/cdm4/item_viewer.php?CISOROOT=/p4013coll11&CISOPTR=175&REC=1 ''An Abridged History of the Army Attack Helicopter Program'']. Washington, DC: Department of the Army. 1973.

==External links==
* [http://www.globalsecurity.org/military/systems/aircraft/ah-63.htm YAH-63 page on GlobalSecurity.org]
* [http://www.janes.com/defence/air_forces/news/jawa/jawa001013_1_n.shtml Jane's AH-64 page]
* [http://www.globalsecurity.org/military/systems/aircraft/ah-64.htm AH-64 page on GlobalSecurity.com]

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[[Category:Military helicopters]]
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