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{{short description|Prototype attack aircraft developed for the US Air Force A-X program}} |
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{|{{Infobox aircraft begin |
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<!-- This article is a part of [[Wikipedia:WikiProject Aircraft]]. Please see [[Wikipedia:WikiProject Aircraft/page content]] for recommended layout, and guidelines. --> |
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{|{{Infobox Aircraft Begin |
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|name = YA-9 |
|name = YA-9 |
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|image = Northrop YA-9 prototype.jpg |
|image = File:Northrop YA-9 prototype.jpg |
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|caption = |
|caption = |
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}}{{Infobox |
}}{{Infobox aircraft type |
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|type = Attack aircraft |
|type = [[Attack aircraft]] |
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|manufacturer = [[Northrop Corporation |
|manufacturer = [[Northrop Corporation]] |
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|designer = |
|designer = |
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|first flight = 30 May 1972 |
|first flight = 30 May 1972{{sfn|Jenkins|1998|p=26}} |
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|introduced = |
|introduced = |
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|retired = |
|retired = |
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|status = |
|status = Cancelled |
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|primary user = [[United States Air Force]] |
|primary user = [[United States Air Force]] |
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|more users = [[NASA]] |
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|more users = |
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|produced = |
|produced = |
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|number built = 2 |
|number built = 2 |
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|unit cost = |
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|variants with their own articles = |
|variants with their own articles = |
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}} |
}} |
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==Design and development== |
==Design and development== |
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Criticism that the U.S. Air Force did not take [[close air support]] seriously prompted a few service members to seek a specialized attack aircraft.{{sfn|Coram|2004}}{{page needed|date=March 2021}} In the [[Vietnam War]], large numbers of ground-attack aircraft were shot down by [[small arms]], [[Surface-to-air missile|surface-to-air missiles]], and low-level anti-aircraft gunfire, prompting the development of an aircraft better able to survive such weapons. Fast jets such as the [[North American F-100 Super Sabre]], [[Republic F-105 Thunderchief]], and [[McDonnell Douglas F-4 Phantom II]] proved for the most part to be ineffective for close air support. The [[Douglas A-1 Skyraider]] was the USAF's primary close air support aircraft.{{sfn|Donald|March|2004|p=8}} |
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===Background=== |
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Criticism that the U.S. Air Force did not take [[close air support]] seriously prompted a few service members to seek a specialized attack aircraft.<ref name="Boyd">Coram, Robert. ''Boyd: The Fighter Pilot Who Changed the Art of War''. Los Angeles: Back Bay Books, 2004. ISBN 0-316-79688-3.</ref> In the [[Vietnam War]], large numbers of ground-attack aircraft were shot down by [[small arms]], [[surface-to-air missile]]s, and low-level anti-aircraft gunfire, prompting the development of an aircraft better able to survive such weapons. Fast jets such as the [[North American F-100 Super Sabre]], [[Republic F-105 Thunderchief]], and [[McDonnell Douglas F-4 Phantom II]] proved for the most part to be ineffective for close air support. The [[Douglas A-1 Skyraider]] was the USAF's primary close air support aircraft.<ref name=Donald_p8>Donald and March 2004, p. 8.</ref> |
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===A-X=== |
===A-X=== |
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In mid-1966, the U.S. Air Force formed the Attack Experimental (A-X) program office. |
In mid-1966, the U.S. Air Force formed the Attack Experimental (A-X) program office.{{sfn|Jenkins|1998|p=12}} On 6 March 1967, the Air Force released a [[request for information]] to 21 [[defense contractor]]s for the A-X. The objective was to create a design study for a low-cost attack aircraft.{{sfn|Coram|2004}}{{page needed|date=March 2021}} Discussions with A-1 Skyraider pilots operating in Vietnam and analysis of the effectiveness of current aircraft used in the role indicated the ideal aircraft should have long loiter time, low-speed maneuverability, massive cannon firepower, and extreme survivability;{{sfn|Coram|2004}}{{page needed|date=March 2021}} an aircraft that had the best elements of the [[Ilyushin Il-2]], [[Henschel Hs 129]] and Skyraider.{{sfn|Coram|2004}}{{page needed|date=March 2021}} While turboprop engines were requested in the initial request, by May 1969, requirements had changed to specify use of [[turbofan]] engines.{{sfn|Jesse|Engbrecht|1996|p=58}} |
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In May 1970, the USAF issued a modified, and much more detailed [[request for proposal]]s (RFP). The threat of Soviet armored forces and all-weather attack operations had become more serious. Now included in the requirements was that the aircraft would be designed specifically for the [[30 mm caliber|30 mm]] cannon. The RFP also called for an aircraft with a maximum speed of {{convert|460|mph|km/h|abbr=on|sigfig=2}}, takeoff distance of {{convert|4000|ft|m|sigfig=2}}, external load of {{convert|16000|lb|kg|sigfig=2}}, {{convert|285|mi|km|adj=on|sigfig=2}} mission radius, and a unit cost of US$1.4 million. |
In May 1970, the USAF issued a modified, and much more detailed [[request for proposal]]s (RFP). The threat of Soviet armored forces and all-weather attack operations had become more serious. Now included in the requirements was that the aircraft would be designed specifically for the [[30 mm caliber|30 mm]] cannon. The RFP also called for an aircraft with a maximum speed of {{convert|460|mph|km/h|abbr=on|sigfig=2}}, takeoff distance of {{convert|4000|ft|m|sigfig=2}}, external load of {{convert|16000|lb|kg|sigfig=2}}, {{convert|285|mi|km|adj=on|sigfig=2}} mission radius, and a unit cost of US$1.4 million.{{sfn|Jenkins|1998|pp=16–17}} Simplicity and low cost were also vital requirements, with a maximum [[flyaway cost]] of $1.4 million based on a 600 aircraft production run. Performance was to be sacrificed where necessary to keep development and production costs under control.{{sfn|Jesse|Engbrecht|1996|pp=58–59}}{{sfn|Aviation Week|1972|p=109}} During this time, a separate RFP was released for A-X's 30 mm cannon with requirements for a high rate of fire (4,000 round/minute) and a high muzzle velocity.{{sfn|Jenkins|1998|p=19}} Six companies submitted proposals to the USAF, with [[Northrop Corporation|Northrop]] and [[Fairchild Aircraft|Fairchild Republic]] selected on18 December 1970 to build prototypes: the YA-9A and YA-10A, respectively. Meanwhile, General Electric and Philco-Ford were selected to build and test [[GAU-8 Avenger|GAU-8]] cannon prototypes.{{sfn|Jenkins|1998|pp=18, 20}} |
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===Design=== |
===Design=== |
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The A-9 was a |
The A-9 was a shoulder-wing [[monoplane]] of all-riveted [[aluminum alloy]] construction, with [[honeycomb structure]]s and [[Chemical milling|chemically milled]] skins. The required twin turbofans were fitted in nacelles under the aircraft's wing roots.{{#tag:ref|By comparison, the A-10 engine location at the tail is less conventional, but offers greater survivability in the case of a hit on the engine area. The double tail of the A-10 also hides the engine infrared and noise signature, and incorporates redundancy in case one of the tails is shot away.{{cn|date=January 2022}}|group=lower-alpha}} Northrop selected the {{convert|7200|lbf|kN|abbr=on}} [[Lycoming YF102]] engine for the YA-9 rather than the more powerful ({{convert|9280|lbf|kN|abbr=on}}) [[General Electric TF34]] used by the A-10, although either engine could be accommodated. The YF102 engine was a new design, based on the [[Avco Lycoming T55]] [[turboshaft]] that powered the [[Boeing CH-47 Chinook]] helicopter, which was selected in order to minimize costs.{{sfn|Jesse|Engbrecht|1996|p=58}}{{sfn|Aviation Week|1972|p=109}} The aircraft had a large cruciform [[Stabilizer (aeronautics)|stabilizer]] in order to improve directional stability for low-level flight. Split [[aileron]]s were fitted that could be used as [[Air brake (aeronautics)|airbrake]]s. When these airbrakes were operated asymmetrically in conjunction with the aircraft's [[rudder]], sideways control forces could be applied (and the aircraft moved sideways) without [[Aircraft principal axes#Vertical axis .28yaw.29|yawing]] or [[Banked turn|banking]], easing weapon aiming.{{sfn|Jesse|Engbrecht|1996|p=58}}{{sfn|Fink|1972a|pp=45–46}} |
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The pilot sat under a large bubble canopy well ahead of the leading edge of the wings. The cockpit was surrounded by a bathtub of armor (aluminum in the prototypes, which would have been replaced by [[titanium]] if production occurred) while the wing-mounted fuel tanks were self |
The pilot sat under a large bubble canopy well ahead of the leading edge of the wings. The cockpit was surrounded by a bathtub of armor (aluminum in the prototypes, which would have been replaced by [[titanium]] if production occurred) while the wing-mounted fuel tanks were self-sealing and filled with foam to minimize the potential for fires or massive fuel loss. Dual redundant hydraulic flight control systems were fitted, with a further manual backup to prevent a single hit from causing control failure. These design features were hoped to reduce combat losses by as much as 90% in Vietnam-type operations.{{sfn|Jesse|Engbrecht|1996|p=58}}{{sfn|Aviation Week|1972|p=113}} A single 30 mm [[rotary cannon]] was to be fitted in the belly of the aircraft, with the gun barrels extending under the nose. As the gun was mounted on the aircraft's centerline, the undercarriage nosewheel was offset {{convert|1|ft|m|spell=in}} to the left. As the [[GAU-8 Avenger]] cannon was not ready, both YA-9 prototypes (and the two YA-10s) were fitted with the smaller 20 mm [[M61 Vulcan]] instead. Ten underwing [[hardpoint]]s were fitted, allowing up to {{convert|16000|lb|kg|abbr=on}} of weapons, including bombs and [[AGM-65 Maverick]] [[air-to-ground missile]]s, to be carried.{{sfn|Jesse|Engbrecht|1996|p=59}} |
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The A-9 used the Lycoming F-102 engine, while the A-10 used the GE [[TF34]].<ref>"The Fairchild A-10A: More Thunder for the USAF", ''[[Air International|Air Enthusiast International]]'', Vol. 6, No 5, May 1974, p. 220.</ref> The YA-9 took its first flight on 30 May 1972.<ref name=Jenkins_p26>Jenkins 1998, p. 26.</ref><ref name=Donald_p9>Donald and March 2004, p. 9.</ref> |
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===Fly-off=== |
===Fly-off=== |
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Apart from aircraft themselves, the A-X program was also developing a powerful cannon for the winning plane to carry. Eventually, this would result in the [[GAU-8 Avenger]], but for trials, the YA-9 and YA-10 were both equipped with the smaller [[M61 Vulcan]] [[Gatling gun]]. By comparison, the A-10 engine location at the tail is less conventional, but offers greater survivability in the case of a hit on the engine area. The double tail of the A-10 also hides the engine infrared and noise signature, and incorporates redundancy in case one of the tails is shot away. |
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The YA-9 took its first flight on 30 May 1972,{{sfn|Jenkins|1998|p=26}}{{sfn|Donald|March|2004|p=9}} with the second prototype flying on 23 August.{{sfn|Jesse|Engbrecht|1996|p=59}} Northrop's flight testing was successful, with the aircraft claimed to have "fighter-like" handling and to be a good weapon platform.{{sfn|Fink|1972a|pp=44–46}} A fly-off by USAF test pilots of the two competing designs took place between 10 October and 9 December 1972.{{sfn|Fink|1972b|p=20}} While the YA-9 fully met the USAF's requirements, the YA-10 was declared the winner on 18 January 1973. The use of the established TF34 engine by the YA-10 rather than the untried F102 may have been preferred by the Air Force, while Fairchild had no alternative work available and was unlikely to survive if it did not win the A-X contract.{{sfn|Jesse|Engbrecht|1996|p=59}} |
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A fly-off of the two prototypes took place between 10 October and 9 December 1972, with the YA-10 declared the winner on 18 January 1973. |
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The two YA-9 prototypes were subsequently relegated to [[NASA]] for continued flight testing before being |
The two YA-9 prototypes were subsequently relegated to [[NASA]] for continued flight testing before being retired.{{sfn|Jesse|Engbrecht|1996|p=59}} When retired, the YA-9s' custom-built engines were removed and were later mated to a [[C-8 Buffalo]] airframe as part of the NASA-[[Boeing]] joint Quiet Short-haul Research Aircraft (QSRA) study into a quiet short-haul commercial aircraft.{{sfn|Richardson|1978|pp=29–30}} |
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==Aircraft disposition== |
==Aircraft disposition== |
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[[File:Northrop YA-9A ‘11368’ (26683410563).jpg|thumb|Northrop YA-9A display at the [[March Field Air Museum]], Riverside, |
[[File:Northrop YA-9A ‘11368’ (26683410563).jpg|thumb|Northrop YA-9A display at the [[March Field Air Museum]], Riverside, California]] |
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*71-1367 - storage yard awaiting restoration at [[Edwards AFB]], [[California]].<ref> |
* 71-1367 - storage yard awaiting restoration at [[Edwards AFB]], [[California]].<ref>{{cite web |title= Aviation History And Aircraft Photography: A-9A |work= JohnWeeks.com |url= http://www.johnweeks.com/a9a/a9aafftcm.html |access-date= 2 March 2021}}</ref> |
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*71-1368 - on display at [[March Field Air Museum]], [[March Air Reserve Base]], |
* 71-1368 - on display at [[March Field Air Museum]], [[March Air Reserve Base]], California.<ref>{{cite web |title= YA-9A |work= March Field Air Museum |url= https://www.marchfield.org/aircraft/attack/ya-9a-northrop/ |access-date= 2 March 2021}}</ref> |
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==Specifications (YA-9A)== |
==Specifications (YA-9A)== |
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[[File:Northrop |
[[File:Northrop-ya-9.png|frameless|right|3-view line drawing of the Northrop YA-9]] |
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[[File:Northrop A-9A parked.jpg|thumb|A rear view]] |
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{{Aircraft |
{{Aircraft specs |
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|ref= Airdata File: Northrop A-9A{{sfn|''Air Enthusiast'' September 1972|p=160}} |
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|prime units?=kts |
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|plane or copter?=plane |
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|jet or prop?=jet |
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General characteristics |
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|ref= Airdata File: Northrop A-9A<ref name="AI972 p160">''Air Enthusiast'' September 1972, p. 160.</ref> |
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|crew=1 |
|crew=1 |
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|length |
|length ft=53 |
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|length |
|length in=6 |
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|length note= |
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|span main=58 ft 0 in |
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|span |
|span ft=58 |
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|span in=0 |
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|height main=16 ft 11 in |
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|span note= |
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|height alt=5.15 m |
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|height ft=16 |
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|area main=580 sq ft |
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|height in=11 |
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|area alt=53.88 m<sup>2</sup> |
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|height note= |
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|empty weight main= |
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|wing area sqft=580 |
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|empty weight alt= |
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|wing area note= |
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|loaded weight main=25,000 lb |
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|aspect ratio=<!-- sailplanes --> |
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|loaded weight alt=11,340 kg |
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|airfoil=<!--'''root:''' [[NACA airfoil|NACA ]]; '''tip:''' [[NACA airfoil|NACA ]]<ref name="Selig">{{cite web |last1=Lednicer |first1=David |title=The Incomplete Guide to Airfoil Usage |url=https://m-selig.ae.illinois.edu/ads/aircraft.html |website=m-selig.ae.illinois.edu |accessdate=16 April 2019}}</ref>--> |
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|max takeoff weight main=41,000 lb |
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|empty weight lb= |
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|empty weight note= |
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|gross weight lb=25000 |
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|gross weight note= |
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|max takeoff weight lb=41000 |
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|max takeoff weight note= |
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|fuel capacity= |
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|more general= |
|more general= |
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<!-- |
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Powerplant |
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--> |
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|eng1 number=2 |
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|eng1 name=[[Lycoming YF102-LD-100]] |
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|eng1 type=[[turbofan]] engines |
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|eng1 lbf=7200 |
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|eng1 note= |
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<!-- |
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Performance |
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--> |
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|max speed kts=452 |
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|max speed note= |
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|max speed mach=<!-- supersonic aircraft --> |
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|cruise speed nmi= |
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|cruise speed note= |
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|stall speed nmi= |
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|stall speed note= |
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|never exceed speed nmi= |
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|never exceed speed note= |
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|minimum control speed nmi= |
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|minimum control speed note= |
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|range nmi= |
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|range note= |
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|combat range nmi= |
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|combat range note= |
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|ferry range nmi= |
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|ferry range note= |
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|endurance=<!-- if range unknown --> |
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|ceiling ft= |
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|ceiling note= |
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|g limits=<!-- aerobatic --> |
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|roll rate=<!-- aerobatic --> |
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|glide ratio=<!-- sailplanes --> |
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|climb rate ftmin=5000 |
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|climb rate note= |
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|time to altitude= |
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|lift to drag= |
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|wing loading lb/sqft= |
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|wing loading note= |
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|fuel consumption lb/mi= |
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|thrust/weight= |
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|more performance=<!--</br> |
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|engine (jet)=[[Honeywell ALF 502|Lycoming YF102-LD-100]] |
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*'''Take-off run:''' {{cvt||ft|0}} |
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|type of jet=[[turbofan]]s |
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*'''Take-off distance to {{cvt|50|ft|0}}:''' {{cvt||ft|0}} |
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|number of jets=2 |
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*'''Landing run:''' {{cvt||ft|0}} |
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|thrust main=7,200 lbf |
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*'''Landing distance from {{cvt|50|ft|0}}:''' {{cvt||ft|0}}--> |
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|thrust alt=32.1 kN |
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<!-- |
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Armament |
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--> |
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|guns=1x 20 mm [[M61 Vulcan]] [[Gatling gun]] (Substitute for [[GAU-8/A]]) |
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|hardpoints=10 underwing |
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|hardpoint capacity={{convert|16,000|lb|kg|abbr=on}} |
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|avionics= |
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|max speed main=520 mph |
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|max speed alt=837 km/h |
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|combat radius main=288 mi |
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|combat radius alt=463 km |
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|range main= |
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|range alt= |
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|ceiling main= |
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|ceiling alt= |
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|climb rate main=5000 ft/min |
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|climb rate alt=25.4 ft/s |
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|loading main= |
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|loading alt= |
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|thrust/weight= |
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|more performance= |
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|armament= |
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* 1x 20 mm [[M61 Vulcan]] [[Gatling gun]] (Substitute for [[GAU-8/A]]) |
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* Up to 16,000 lb (7,260 kg) of ordnance |
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}} |
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|related= |
|related= |
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|similar aircraft= |
|similar aircraft= |
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*[[Fairchild Republic A-10 Thunderbolt II]] |
* [[Fairchild Republic A-10 Thunderbolt II]] |
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*[[ |
* [[Ilyushin Il-102]] |
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*[[ |
* [[Sukhoi Su-25]] |
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|lists= |
|lists= |
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*[[List of attack aircraft]] |
* [[List of attack aircraft]] |
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*[[List of military aircraft of the United States]] |
* [[List of military aircraft of the United States]] |
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}} |
}} |
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==References== |
==References== |
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{{Reflist|group=lower-alpha}} |
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;Notes |
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{{Reflist|30em}} |
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===Notes=== |
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;Bibliography |
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{{ |
{{Reflist}} |
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*[http://archive.aviationweek.com/issue/19720626/#!&pid=102 "AX Fighter Paved Way for Prototyping"]. ''[[Aviation Week and Space Technology]]'', Volume 96, No. 26, June 26, 1972. pp. 103–104. (Registration required). |
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*"Airdata File". ''[[Air Enthusiast|Air International]]'', Vol. 3 No. 3, July 1972. pp. 156–160. ISBN 0-903234-31-9. |
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*Donald, David and Daniel J. March, eds. "A-10 Fighting Warthog". ''Modern Battlefield Warplanes''. Norwalk, CT: AIRtime, 2004. ISBN 1-880588-76-5. |
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*Donald, David, ed. "Northrop YA-9". ''The Complete Encyclopedia of World Aircraft''. Barnes & Noble Books, 1997. ISBN 0-7607-0592-5. |
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*Jenkins, Dennis R. ''Fairchild-Republic A/OA-10 Warthog''. North Branch, Minnesota: Specialty Press, 1998. ISBN 1-58007-013-2. |
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*Fink, Donald E. [http://archive.aviationweek.com/issue/19721002/#!&pid=44 "Contractors Prepare for 90-Day AX Flyoff"]. ''Aviation Week and Space Technology'', Volume 97, No. 14. October 2, 1972. pp. 44–48. (Registration required). |
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*Fink, Donald E. [http://archive.aviationweek.com/issue/19721211/#!&pid=20 "USAF Completes AX Flight Evaluations"]. Volume 97, No. 24. December 11, 1972. p.20. (Registration required). |
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*Jesse, William and Engbrecht, Bradley. "Not Quite Ten: Northrop's A-9, A-X runner-up". ''[[Air Enthusiast]]'', No. 64, July–August 1994. pp. 57–59. {{ISSN|0143-5450}}. |
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*[http://archive.aviationweek.com/issue/19720626/#!&pid=106 "Northrop Streamlines A-9A Management"]. ''Aviation Week and Space Technology'', Volume 96, No. 26, June 26, 1972. pp. 107–113. (Registration required). |
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===Bibliography=== |
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{{Refend}} |
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* {{cite magazine |title= AX Fighter Paved Way for Prototyping |magazine= [[Aviation Week and Space Technology]] |volume= 96 |issue= 26 |date= 26 June 1972 |pages=103–104 |url= http://archive.aviationweek.com/issue/19720626/#!&pid=102 |url-access= subscription |ref=none }} |
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* {{cite magazine |title= Airdata File |magazine= [[Air International|Air Enthusiast]] |volume= 3 |number= 3 |date= September 1972 |pages= 156–160 |isbn= 0-903234-31-9 |ref={{harvid|''Air Enthusiast'' September 1972}}}} |
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* {{cite book |last= Coram |first= Robert |title= Boyd: The Fighter Pilot Who Changed the Art of War |location= Los Angeles |publisher= Back Bay Books |date= 2004 |isbn= 0-316-79688-3}} |
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* {{cite encyclopedia |editor-last1= Donald |editor-first1= David |editor-last2= March |editor-first2= Daniel |title= A-10 Fighting Warthog |encyclopedia= Modern Battlefield Warplanes |location= Norwalk, Connecticut |publisher= AIRtime |date= 2004 |isbn= 1-880588-76-5}} |
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* {{cite encyclopedia |editor-last= Donald |editor-first= David |title= Northrop YA-9 |encyclopedia= The Complete Encyclopedia of World Aircraft |publisher= Barnes & Noble Books |date= 1997 |isbn= 0-7607-0592-5 |ref=none}} |
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* {{cite magazine |last= Fink |first= Donald E. |year= 1972a |title= Contractors Prepare for 90-Day AX Flyoff |magazine= Aviation Week and Space Technology |volume= 97 |number= 14 |date= 2 October 1972 |pages= 44–48 |url= http://archive.aviationweek.com/issue/19721002/#!&pid=44 |url-access= subscription}} |
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* {{cite magazine |last= Fink |first= Donald E. |year= 1972b |title= USAF Completes AX Flight Evaluations |magazine= Aviation Week and Space Technology |volume= 97 |number= 24 |date= 11 December 1972 |page= 20 |url= http://archive.aviationweek.com/issue/19721211/#!&pid=20 |url-access= subscription}} |
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* {{cite book |last= Jenkins |first= Dennis R. |title= Fairchild-Republic A/OA-10 Warthog |location= North Branch, Minnesota |publisher= Specialty Press |date= 1998 |isbn= 1-58007-013-2}} |
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* {{cite magazine |last1= Jesse |first1= William |last2= Engbrecht |first2= Bradley |title= Not Quite Ten: Northrop's A-9, A-X runner-up |magazine= [[Air Enthusiast]] |number= 64 |date= July 1996 |pages= 57–59 |issn= 0143-5450}} |
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* {{cite magazine |title= Northrop Streamlines A-9A Management |magazine= Aviation Week and Space Technology |volume= 96 |number= 26 |date= 26 June 1972 |pages= 107–113 |url= http://archive.aviationweek.com/issue/19720626/#!&pid=106 |url-access= subscription |ref= {{sfnref|Aviation Week|1972}} }} |
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* {{cite magazine |last= Richardson |first= Doug |title= Quiet and vertical at NASA Ames |magazine= [[Flight International]] |volume= 114 |number= 3515 |date= 1 July 1978 |pages= 29–32 |url= https://www.flightglobal.com/pdfarchive/view/1978/1978%20-%201073.html |url-access= registration}} |
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==External links== |
==External links== |
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{{Commons|Northrop YA-9}} |
{{Commons|Northrop YA-9}} |
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*[http://www.aero-web.org/specs/northrop/ya-9a.htm YA-9A page on aero-web.org] |
*[https://web.archive.org/web/20100622075307/http://www.aero-web.org/specs/northrop/ya-9a.htm YA-9A page on aero-web.org] |
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{{Northrop aircraft}} |
{{Northrop aircraft}} |
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[[Category:Twinjets]] |
[[Category:Twinjets]] |
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[[Category:Northrop aircraft|A-09]] |
[[Category:Northrop aircraft|A-09]] |
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[[Category:United States attack aircraft |
[[Category:1970s United States attack aircraft|Northrop A-09]] |
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[[Category:Cancelled military aircraft projects of the United States]] |
[[Category:Cancelled military aircraft projects of the United States]] |
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[[Category:High-wing aircraft]] |
[[Category:High-wing aircraft]] |
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[[Category:Aircraft first flown in 1972]] |
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Find sources: "Northrop YA-9" – news · newspapers · books · scholar · JSTOR (June 2010) (Learn how and when to remove this message) |
| YA-9 | |
|---|---|
| |
| Role | Attack aircraft
Type of aircraft
|
| Manufacturer | Northrop Corporation |
| First flight | 30 May 1972[1] |
| Status | Cancelled |
| Primary users | United States Air Force NASA |
| Number built | 2 |
The Northrop YA-9 was a prototype attack aircraft developed for the United States Air Force A-X program. The YA-9 was passed over in preference for the Fairchild Republic YA-10 that entered production as the A-10 Thunderbolt II.
Criticism that the U.S. Air Force did not take close air support seriously prompted a few service members to seek a specialized attack aircraft.[2][page needed] In the Vietnam War, large numbers of ground-attack aircraft were shot down by small arms, surface-to-air missiles, and low-level anti-aircraft gunfire, prompting the development of an aircraft better able to survive such weapons. Fast jets such as the North American F-100 Super Sabre, Republic F-105 Thunderchief, and McDonnell Douglas F-4 Phantom II proved for the most part to be ineffective for close air support. The Douglas A-1 Skyraider was the USAF's primary close air support aircraft.[3]
In mid-1966, the U.S. Air Force formed the Attack Experimental (A-X) program office.[4] On 6 March 1967, the Air Force released a request for information to 21 defense contractors for the A-X. The objective was to create a design study for a low-cost attack aircraft.[2][page needed] Discussions with A-1 Skyraider pilots operating in Vietnam and analysis of the effectiveness of current aircraft used in the role indicated the ideal aircraft should have long loiter time, low-speed maneuverability, massive cannon firepower, and extreme survivability;[2][page needed] an aircraft that had the best elements of the Ilyushin Il-2, Henschel Hs 129 and Skyraider.[2][page needed] While turboprop engines were requested in the initial request, by May 1969, requirements had changed to specify use of turbofan engines.[5]
In May 1970, the USAF issued a modified, and much more detailed request for proposals (RFP). The threat of Soviet armored forces and all-weather attack operations had become more serious. Now included in the requirements was that the aircraft would be designed specifically for the 30 mm cannon. The RFP also called for an aircraft with a maximum speed of 460 mph (740 km/h), takeoff distance of 4,000 feet (1,200 m), external load of 16,000 pounds (7,300 kg), 285-mile (460 km) mission radius, and a unit cost of US$1.4 million.[6] Simplicity and low cost were also vital requirements, with a maximum flyaway cost of $1.4 million based on a 600 aircraft production run. Performance was to be sacrificed where necessary to keep development and production costs under control.[7][8] During this time, a separate RFP was released for A-X's 30 mm cannon with requirements for a high rate of fire (4,000 round/minute) and a high muzzle velocity.[9] Six companies submitted proposals to the USAF, with Northrop and Fairchild Republic selected on 18 December 1970 to build prototypes: the YA-9A and YA-10A, respectively. Meanwhile, General Electric and Philco-Ford were selected to build and test GAU-8 cannon prototypes.[10]
The A-9 was a shoulder-wing monoplane of all-riveted aluminum alloy construction, with honeycomb structures and chemically milled skins. The required twin turbofans were fitted in nacelles under the aircraft's wing roots.[a] Northrop selected the 7,200 lbf (32 kN) Lycoming YF102 engine for the YA-9 rather than the more powerful (9,280 lbf (41.3 kN)) General Electric TF34 used by the A-10, although either engine could be accommodated. The YF102 engine was a new design, based on the Avco Lycoming T55 turboshaft that powered the Boeing CH-47 Chinook helicopter, which was selected in order to minimize costs.[5][8] The aircraft had a large cruciform stabilizer in order to improve directional stability for low-level flight. Split ailerons were fitted that could be used as airbrakes. When these airbrakes were operated asymmetrically in conjunction with the aircraft's rudder, sideways control forces could be applied (and the aircraft moved sideways) without yawingorbanking, easing weapon aiming.[5][11]
The pilot sat under a large bubble canopy well ahead of the leading edge of the wings. The cockpit was surrounded by a bathtub of armor (aluminum in the prototypes, which would have been replaced by titanium if production occurred) while the wing-mounted fuel tanks were self-sealing and filled with foam to minimize the potential for fires or massive fuel loss. Dual redundant hydraulic flight control systems were fitted, with a further manual backup to prevent a single hit from causing control failure. These design features were hoped to reduce combat losses by as much as 90% in Vietnam-type operations.[5][12] A single 30 mmrotary cannon was to be fitted in the belly of the aircraft, with the gun barrels extending under the nose. As the gun was mounted on the aircraft's centerline, the undercarriage nosewheel was offset one foot (0.30 m) to the left. As the GAU-8 Avenger cannon was not ready, both YA-9 prototypes (and the two YA-10s) were fitted with the smaller 20 mmM61 Vulcan instead. Ten underwing hardpoints were fitted, allowing up to 16,000 lb (7,300 kg) of weapons, including bombs and AGM-65 Maverick air-to-ground missiles, to be carried.[13]
The YA-9 took its first flight on 30 May 1972,[1][14] with the second prototype flying on 23 August.[13] Northrop's flight testing was successful, with the aircraft claimed to have "fighter-like" handling and to be a good weapon platform.[15] A fly-off by USAF test pilots of the two competing designs took place between 10 October and 9 December 1972.[16] While the YA-9 fully met the USAF's requirements, the YA-10 was declared the winner on 18 January 1973. The use of the established TF34 engine by the YA-10 rather than the untried F102 may have been preferred by the Air Force, while Fairchild had no alternative work available and was unlikely to survive if it did not win the A-X contract.[13]
The two YA-9 prototypes were subsequently relegated to NASA for continued flight testing before being retired.[13] When retired, the YA-9s' custom-built engines were removed and were later mated to a C-8 Buffalo airframe as part of the NASA-Boeing joint Quiet Short-haul Research Aircraft (QSRA) study into a quiet short-haul commercial aircraft.[17]
Data from Airdata File: Northrop A-9A[20]
General characteristics
Performance
Armament
Aircraft of comparable role, configuration, and era
Related lists
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Northrop aircraft and aircraft engines
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