General Dynamics F-16XL

File:Scamp team1.jpg

Shortly after winning the lightweight fighter program, General Dynamics Fort Worth began investigating possible {{nowrap|F-16}} derivatives with the goal of enhancing both air-to-air and air-to-ground mission capabilities while retaining parts commonality with the {{nowrap|F-16A}}.{{harvnb|Piccirillo|2014|p=7}}: "These were oriented to extending range and payload, expanding basic missions, and developing advanced versions or derivative configurations of the aircraft. Importantly, these were intended to enhance both air-to-air and air-to-ground capabilities while retaining the maximum possible commonality with the basic F-16 design." Under the leadership of Harry Hillaker (designer of the original {{nowrap|F-16}}), the Supersonic Cruise and Maneuver Prototype (SCAMP) project was started. Several wing designs were considered, including one using a forward-swept wing, but the large "cranked-arrow" wing (similar to that of the Saab 35 Draken){{NoteTag |The "cranked-arrow" delta wing originated with the Draken, which was studied by General Dynamics engineers during the SCAMP program.{{sfn|Piccirillo|2014|p=7-10}}}} was pursued due to its much more efficient lift-to-drag ratio at supersonic speeds.{{sfn|Piccirillo|2014|p=7-10}}

The company worked closely with NASA's Langley Research Center{{sfn|Chambers|2000|pp=156-158}} and invested significant R&D funds for wind tunnel testing. Over several years the design was refined which led to the final {{nowrap|F-16XL}} design by late 1980.{{sfn|Piccirillo|2014|pp=34-35, 69-70}}

File:F-16 and F-16XL aerial top down view.jpg

In 1980, the USAF signed on as a partner,{{sfn|Piccirillo|2014|loc=Chapter 3}} providing the fuselages of the third{{NoteTag |Serial number 75-0747; would become F-16XL-2; had been severely damaged in an airshow accident in October 1980}} and fifth{{NoteTag |Serial number 75-0749; would become F-16XL-1}} production {{nowrap|F-16}}s for conversion. These two fuselages became the only examples of the {{nowrap|F-16XL}}.{{harvnb|Piccirillo|2014|pp=76–77}}

In March 1981, the USAF announced the Enhanced Tactical Fighter (ETF) program to procure a replacement for the F-111 Aardvark.{{sfn|Piccirillo|2014|p=149}} The concept envisioned an aircraft capable of launching deep interdiction missions without requiring additional support in the form of fighter escorts or jamming support. General Dynamics submitted the {{nowrap|F-16XL,}} while McDonnell Douglas submitted a variant of the F-15 Eagle. Though the two aircraft were competing for the same role, they had fairly different design approaches. The {{nowrap|F-15E}} required very few alterations from its base {{nowrap|F-15B or D}}, while the {{nowrap|F-16XL}} had major structural and aerodynamic differences from the original {{nowrap|F-16}}.{{harvnb|Piccirillo|2014|p=159}}: "...the F-16E required major changes to the basic F-16 airframe. ... Changes required for the F-15E were not considered by the GAO to be as great as those needed for the F-16E, and mainly consisted of structural modifications to the wings as well as a strengthened landing gear." As such, the {{nowrap|F-16XL}} would have required much more effort, time, and money to put into full production.{{harvnb|Piccirillo|2014|pp=156–157}} Additionally, the {{nowrap|F-15E}} had two engines, which gave it a much higher maximum takeoff weight and redundancy in the case of engine failure.{{NoteTag |F-16E would have had a maximum takeoff weight of {{convert|48000|lb|kg}} versus F-15E's {{convert|80000|lb|kg}}}}

In February 1984, the USAF awarded the ETF contract to McDonnell Douglas.{{sfn|Piccirillo|2014|p=161}}{{cite web |title=February 24, 1984: F-15 Became the Air Force's New Dual-Role Fighter |url=https://www.aftc.af.mil/News/On-This-Day-in-Test-History/Article-Display-Test-History/Article/2481449/february-24-1984-f-15-became-the-air-forces-new-dual-role-fighter/ |website=www.aftc.af.mil |publisher=Air Force Flight Test Center |access-date=8 March 2023 |date=24 February 2021 |archive-date=8 March 2023 |archive-url=https://web.archive.org/web/20230308200713/https://www.aftc.af.mil/News/On-This-Day-in-Test-History/Article-Display-Test-History/Article/2481449/february-24-1984-f-15-became-the-air-forces-new-dual-role-fighter/ |url-status=live }}{{Cite web |last=Walton |first=Bill |date=2017-11-11 |title=The F-16XL: This Advanced F-16 Variant Lost Out To The F-15E Strike Eagle, But Was It Better? |url=https://avgeekery.com/f-16xl-advanced-f-16-variant-lost-f-15e-strike-eagle-better/ |access-date=2023-02-12 |website=Avgeekery.com |language=en-US |archive-date=2023-02-12 |archive-url=https://web.archive.org/web/20230212134655/https://avgeekery.com/f-16xl-advanced-f-16-variant-lost-f-15e-strike-eagle-better/ |url-status=live }} The two {{nowrap|F-16XLs}} were returned to the Air Force and placed in storage at Edwards Air Force Base.{{sfn|Piccirillo|2014|p=169}} Had General Dynamics won the competition, the {{nowrap|F-16XL}} would have gone into production as the F-16E/F (E for single seat, F for two seats).{{sfn|Piccirillo|2014|p=143}}

File:F-16XL loaded with 500lb bombs.jpg and four fuselage-mounted AIM-120 AMRAAM missiles along with 12 Mark 82 500-pound bombs.]]

The wing and rear horizontal control surfaces of the base {{nowrap|F-16A}} were replaced with a cranked-arrow delta wing 115% larger than the original wing.{{harvnb|Piccirillo|2014|p=69}} Extensive use of graphite-bismaleimide composites allowed the savings of {{convert|595|lb|kg}} of weight,{{sfn|Piccirillo|2014|p=74}} but the {{nowrap|F-16XL-1}} and {{nowrap|XL-2}} were {{convert|4100|lb|kg}} and {{convert|5600|lb|kg}} heavier respectively than the original {{nowrap|F-16A}}.{{harvnb|Piccirillo|2014|pp=60–61}}{{NoteTag |Dry weights: XL-1 weighed {{convert|19690|lb|kg}}; XL-2 weighed {{convert|21157|lb|kg}}; F-16A weighed {{convert|15586|lb|kg}}}}

Less noticeable is that the fuselage was lengthened by {{convert|56|in|cm}} by the addition of two sections at the joints of the main fuselage sub-assemblies. With the new wing design, the tail section had to be canted up 3.16°,{{sfn|Piccirillo|2014|p=78}} and the ventral fins removed, to prevent them from striking the pavement during takeoff and landing.{{sfn|Piccirillo|2014|p=75}} The {{nowrap|F-16XL-2}} also received a larger inlet which would go on to be included in later {{nowrap|F-16}} variants.{{sfn|Piccirillo|2014|pp=83-84}}

These changes resulted in a 25% improvement in lift-to-drag ratio in supersonic flight{{harvnb|Piccirillo|2014|p=116}}: "As speed approached Mach 1.0, the F-16XL's comparative cruise efficiency improved, and at Mach 1.4, the F-16XL had a 25-percent-higher lift-to-drag ratio than that of the F-16C." while remaining comparable in subsonic flight,{{harvnb|Piccirillo|2014|p=9}}: "...the L/D ratios of the cranked-arrow, canard-delta, and baseline F-16 were essentially equal at subsonic speeds..." and a plane that reportedly handled smoothly at high speeds and low altitudes.{{cite web |author1=F. Clifton Berry Jr. |title=The Revolutionary Evolution of the F-16XL |url=https://www.airandspaceforces.com/article/1183f16xl/ |website=Air & Space Forces Magazine |access-date=21 February 2023 |archive-date=12 February 2023 |archive-url=https://web.archive.org/web/20230212135422/https://www.airandspaceforces.com/article/1183f16xl/ |url-status=live }} The enlargements increased internal fuel capacity by {{convert|4350|lb|kg}}, or about 65%.{{NoteTag |Just under {{convert|11300|lb|kg}},{{sfn|Piccirillo|2014|p=84}}{{sfn|Piccirillo|2014|p=116}} up from the F-16A's {{convert|6950|lb|kg}}}} The {{nowrap|F-16XL}} could carry twice the ordnance of the {{nowrap|F-16A}} and deliver it 50% farther.{{sfn|Piccirillo|2014|p=291}} The enlarged wing and strengthened hardpoints allowed for a highly configurable payload:{{harvnb|Piccirillo|2014|pp=85–87}}

• 16× {{convert|1000|lb|kg}} wing hardpoints
• 5× {{convert|2000|lb|kg}} wing hardpoints
• 4× semi-recessed AIM-120 AMRAAM stations under fuselage{{NoteTag |Dummy AIM-120s, fabricated from wood & sheet metal, were scabbed onto the undersurfaces of the F-16XL flight demonstrators because the AIM-120 missile had yet to be integrated onto the standard F-16; incorporation of the semisubmerged missile housing with its associated ejector launcher would have required a separate development and integration effort.}}
• 2× wingtip stations
• 1× centerline station{{NoteTag |Intended for a 300-gallon drop tank}}
• 2× wing "heavy/wet" stations{{NoteTag |Intended for either 2× 600-gallon drop tanks or 4× air-to-ground weapons, but not both simultaneously}}
• 2× chin LANTIRN stations

File:F-16XL NASA.jpg F-16XL #2 conducting laminar flow research]]

File:F16xl2_glove_diagram.jpg

File:NASA-F-16XL-and-SR-71A.jpg F-16XL #1 flying alongside a NASA SR-71A]]

In 1988, the two aircraft were turned over to NASA Ames-Dryden Flight Research Facility for supersonic laminar flow research for the High Speed Civil Transport (HSCT) program.{{sfn|Piccirillo|2014|pp=183-184}} The F-16XL was considered ideal for these tests because of its cranked-arrow wing and high-speed, high-altitude capabilities.{{sfn|Anders|Fischer|1999|p=5}} The tests were carried out by a NASA and industry team{{NoteTag |NASA teams included the Ames-Dryden Flight Research Facility and Langley Research Center; industry partners were Boeing, McDonnell Douglas, and Rockwell International{{sfn|Anders|Fischer|1999|p=2}}}} and were intended to achieve laminar flow over the wings, validate computational fluid dynamics (CFD) design methodology, and test active suction systems.{{sfn|Anders|Fischer|1999|p=2}} These tests involved the installation of either passive or active suction aerodynamic gloves. The active suction glove was intended to suck away turbulent airflow over the wings during supersonic flight, restoring laminar flow and reducing drag.{{cite web |title=NASA - NASA Dryden Technology Facts - F-16XL Supersonic Laminar Flow |url=https://www.nasa.gov/centers/dryden/about/Organizations/Technology/Facts/TF-2004-12-DFRC.html |website=www.nasa.gov |publisher=NASA |access-date=4 March 2023 |language=en |archive-date=4 March 2023 |archive-url=https://web.archive.org/web/20230304153523/https://www.nasa.gov/centers/dryden/about/Organizations/Technology/Facts/TF-2004-12-DFRC.html |url-status=live }}{{sfn|Anderson|Bohn-Meyer|1992|pp=2-3}} The NASA Langley Research Center developed and coordinated {{nowrap|F-16XL}} experiments.{{cite web |url= http://www.nasa.gov/centers/dryden/history/pastprojects/F16XL2/index.html |title= Past Projects: F-16XL Ship #2 Supersonic Laminar Flow Control |date= 10 May 2017 |publisher= NASA |access-date= 5 March 2023 |archive-date= 26 November 2022 |archive-url= https://web.archive.org/web/20221126233838/https://www.nasa.gov/centers/dryden/history/pastprojects/F16XL2/index.html |url-status= live }}

{{nowrap|F-16XL-1}} was fitted with an active suction glove encasing the left wing.{{sfn|Piccirillo|2014|pp=199-202}} Designed and built by North American Aviation, it had laser-cut holes that were nominally {{convert|0.0025|in|mm}} diameter at a uniform {{convert|2500|/in2|/cm2}} spacing.{{sfn|Piccirillo|2014|pp=199-202}} The suction was provided by a Convair 880 air-conditioning turbocompressor where the 20mm cannon's ammunition had been.{{harvnb|Piccirillo|2014|pp=183–187}}{{sfn|Piccirillo|2014|pp=199-202}} The glove covered over {{convert|5|sqft|m2}} of the wing. Overall, {{nowrap|F-16XL-1}} completed 31 test flights for these tests from May 1990 to September 1992. Afterwards, it was used to test takeoff performance, engine noise, and sonic boom phenomena.{{sfn|Piccirillo|2014|p=184}}

{{nowrap|F-16XL-2}} had its engine replaced with the more powerful General Electric F110-129.{{sfn|Piccirillo|2014|p=202}} It achieved limited supercruise, a design goal of the {{nowrap|F-16XL}} that was never attained in ETF testing, when it reached {{nowrap|Mach 1.1}} at {{convert|20000|ft|m}} on full military power.{{harvnb|Piccirillo|2014|p=202}}: "F-16XL-2 was also able to demonstrate limited supercruise performance by maintaining Mach 1.1 at an altitude of 20,000 feet in full military power without resorting to the use of afterburner." It was mounted with a passive glove on the right wing and an active suction glove on the left wing. The passive glove was fitted with instruments to measure the flow characteristics over the wing.{{sfn|Piccirillo|2014|p=206}} The active suction glove was designed and fabricated by Boeing; it was made of titanium and had over 12 million laser-cut holes, each {{convert|0.0025|in|mm}} in diameter, spaced {{convert|0.010|to|0.055|in|cm}} apart.{{sfn|Piccirillo|2014|pp=209-210}}{{sfn|Anders|Fischer|1999|p=12}} Suction was provided by a cabin-air pressurization turbocompressor from a Boeing 707, installed where the 20mm ammunition drum had been, which exhausted above the right wing.{{sfn|Piccirillo|2014|pp=211-214}}{{sfn|Anderson|Bohn-Meyer|1992|pp=2-3}} Overall, {{nowrap|F-16XL-2}} performed 45 test flights from October 1995 to November 1996.{{sfn|Anders|Fischer|1999|p=23}}

While "significant progress" was made towards achieving laminar flow at supersonic speeds, neither aircraft achieved the requisite laminar flow characteristics at intended speeds and altitudes.{{sfn|Piccirillo|2014|pp=226-227}}{{sfn|Anderson|Bohn-Meyer|1992|pp=4-5}}{{sfn|Anders|Fischer|1999|pp=40-42}} Nonetheless, NASA officials considered the test program to have been successful. NASA briefly investigated using a Tupolev Tu-144 which would more closely resemble the high-speed civil transport aircraft to continue supersonic laminar flow research, but did not pursue the idea due to a limited budget.{{sfn|Piccirillo|2014|pp=227-228}}

At the conclusion of their test programs in 1999, both {{nowrap|F-16XLs}} were placed into storage at NASA Dryden. In 2007, Boeing and NASA studied the feasibility of returning {{nowrap|F-16XL-1}} to flight status and upgrading it with many of the improvements found in the USAF's {{nowrap|F-16 Block 40}} in order to further test sonic boom mitigation technology.{{harvnb|Piccirillo|2014|pp=281–283}} {{nowrap|F-16XL-1}} was taxi tested at Dryden and given systems checks. However, both {{nowrap|F-16XLs}} were retired in 2009 and stored at Edwards AFB.{{cite web |title=F-16XL (Ship #1) |url=https://www.nasa.gov/centers/dryden/aircraft/F-16XL/index.html |publisher=NASA Armstrong Flight Research Center |access-date=January 31, 2021 |archive-url=https://web.archive.org/web/20160619061105/https://www.nasa.gov/centers/dryden/aircraft/F-16XL/index.html |archive-date=June 19, 2016 |date=April 19, 2011 |url-status=live}}

• 75-0747 – Museum Air Park, Air Force Flight Center Museum, Edwards AFB, California{{cite web |url=https://flighttestmuseum.org/aircraft-inventory-list/ |title=Aircraft Inventory List |publisher=The Flight Test Museum Foundation |access-date=6 March 2023 |archive-date=18 March 2023 |archive-url=https://web.archive.org/web/20230318031320/https://flighttestmuseum.org/aircraft-inventory-list/ |url-status=live }}
• 75-0749 – in storage at the Air Force Flight Center Museum, Edwards AFB, California

File:General Dynamics F-16XL afg-041110-016.jpg

File:F-16XL Scamp Flow Visualization Test - GPN-2000-001935.jpgs illuminate airflow over a model F-16XL in a NASA wind tunnel ]]

{{Aircraft specs

|prime units?=imp

|ref= Darling,{{Harvnb | Darling | 2003 | pages = 63, 64, 69}}. F-16.net,{{Citation | contribution-url = http://www.f-16.net/f-16_versions_article1.html | contribution = F-16 XL, Cranked-Arrow Wing | title = F-16 | access-date = 18 April 2009 | archive-date = 22 April 2009 | archive-url = https://web.archive.org/web/20090422185425/http://www.f-16.net/f-16_versions_article1.html | url-status = live }}. Piccirillo{{sfn|Piccirillo|2014|loc=Chapter 4: Design and Construction Details}}

|crew= One (XL #1) or Two (XL #2)

|length ft=54

|length in=2

|length m=16.51

|span ft=32

|span in=5

|span m=9.88

|span note=({{convert|34|ft|3|in|m}} with an AIM-9 on the wingtip mount){{sfn|Piccirillo|2014|p=71}}

|height ft=17

|height in=7

|height m=5.36

|wing area sqft=663

|wing area sqm=61.6

|empty weight lb=21157

|empty weight kg=9600

|empty weight note=

|gross weight lb=48,000

|gross weight kg=21,800

|max takeoff weight lb=48,000

|max takeoff weight kg=21,800

|eng1 name=General Electric F110-GE-100

|eng1 type=turbofan

|eng1 number=1

|eng1 lbf=17,100

|eng1 lbf-ab=28,900

|max speed kts=1170

|max speed mach=2.0

|max speed note={{NoteTag |Mach 2.0 was only achieved during the supersonic laminar flow tests from around 1990–1992;{{sfn|Piccirillo|2014|p=203}} maximum speed prior had been limited to Mach 1.95, though faster speeds were likely possible.{{sfn|Piccirillo|2014|p=123}}}}

|range nmi=1985

|range miles=2285

|range km=3675

|range note=(longest achieved through October 1985{{sfn|Piccirillo|2014|p=303}})

|ferry range nmi=2245

|ferry range miles=2580

|ferry range km=4160

|ferry range note=(with 2x {{convert|600|gal|L}} drop tanks{{sfn|Piccirillo|2014|p=116}})

|ceiling ft=55,000

|ceiling m=16750

|ceiling note={{sfn|Piccirillo|2014|p=203}}

|climb rate ftmin=62,000

|climb rate note=

|guns= 1 × 20 mm M61 Vulcan rotary cannon{{NoteTag |Ammunition bay was removed in 1991–1992 and replaced with a turbocompressor to provide suction for the aerodynamic glove tests}}

|hardpoints= 17 pylons

|hardpoint capacity= up to {{convert|15000|lb|kg}} of payload (Note: stations 2–5 and 13–16 were split into groups, similar to the F-15E)

}}

{{Portal|Aviation}}

{{aircontent

|see also=

• Tupolev Tu-144
• Saab 35 Draken
• High Speed Civil Transport

|related=

• General Dynamics F-16 Fighting Falcon
• General Dynamics F-16 VISTA

|similar aircraft=

• McDonnell Douglas F-15E Strike Eagle

|lists=

• List of fighter aircraft
• List of military aircraft of the United States

}}

{{Reflist}}

{{NoteFoot}}

• {{cite tech report |last1=Anders |first1=Scott G. |last2=Fischer |first2=Michael C. |date=1 December 1999 |title=F-16XL-2 Supersonic Laminar Flow Control Flight Test Experiment |publisher=NASA Langley Research Center |id=NASA/TP-1999-209683 |url=https://ntrs.nasa.gov/citations/20000004183 |access-date=5 March 2023}}
• {{cite conference |last1=Anderson |first1=Bianca T. |last2=Bohn-Meyer |first2=Marta |title=Overview of supersonic laminar flow control research on the F-16XL ships 1 and 2 |date=1 October 1992 |publisher=NASA |url=https://ntrs.nasa.gov/citations/19930002033 |location=Anaheim, CA |id=93N11221 |access-date=4 March 2023}}
• {{cite book |last1=Chambers |first1=Joseph R. |title=Partners in Freedom: Contributions of the Langley Research Center to U.S. Military Aircraft of the 1990's |date=1 October 2000 |publisher=NASA |url=https://history.nasa.gov/monograph19.pdf |access-date=21 February 2023}}
• {{cite book |last1=Darling |first1=Kev |title=F-16 Fighting Falcon |series=Combat Legend |place=London |publisher=Crowood Press UK |year=2003 |isbn=978-1-84037-399-8}}
• {{cite book |last1=Piccirillo |first1=Albert C. |title=Elegance in Flight: A comprehensive history of the F-16XL experimental prototype and its role in NASA flight research |date=2014 |publisher=NASA |location=Washington, D.C. |isbn=978-1-62683-022-6 |url=https://www.nasa.gov/sites/default/files/atoms/files/elegance_in_flight.pdf |access-date=20 February 2023}}

{{Commons category}}

• {{Citation | url = http://www1.dfrc.nasa.gov/Gallery/Photo/F-16XL1/ | publisher = NASA | title = DFRC | contribution = F-16XL | type = photo gallery | volume = 1 | url-status = dead | archive-url = https://web.archive.org/web/20050908024402/http://www.dfrc.nasa.gov/Gallery/Photo/F-16XL1/ | archive-date = 2005-09-08 }}, [https://web.archive.org/web/20050317081312/http://www1.dfrc.nasa.gov/gallery/photo/F-16XL2/ photo gallery number 2]
• {{Citation | url = http://www.nasa.gov/centers/dryden/pdf/88653main_H-2382.pdf | title = F-16XL experiment report | publisher = NASA | date = December 1999 | place = Dryden | access-date = 2005-05-24 | archive-date = 2023-06-06 | archive-url = https://web.archive.org/web/20230606222500/http://www.nasa.gov/centers/dryden/pdf/88653main_H-2382.pdf | url-status = dead }}.
• {{Citation | url = https://www.airforcemag.com/article/1183f16xl/ | title = The Revolutionary Evolution of the F-16XL | newspaper = Air Force magazine |date=November 1983}}.
• {{Citation | url = http://www.flightglobal.com/articles/2007/07/10/215385/nasa-could-put-f-16xl-back-in-the-air.html | title = NASA Could Put The F-16XL Back In The Air | newspaper = Flight International | year = 2007 | publisher = Flight global}}.
• {{Citation | url = http://www.codeonemagazine.com/article.html?item_id=37 | title = F-16 Designer Harry Hillaker | newspaper = Code One Magazine | year = 1991 | publisher = Lockheed Martin}}.
• {{Citation|url=http://www.codeonemagazine.com/archives/1991/articles/jul_91/july2a_91.html |title=Harry Hillaker — Father of the F-16 |newspaper=Code one |date=Jul 1991 |url-status=dead |archive-url=https://web.archive.org/web/20070202184707/http://www.codeonemagazine.com/archives/1991/articles/jul_91/july2a_91.html |archive-date=February 2, 2007 }}
• {{Citation | url = http://home.att.net/~jbaugher4/f16_29.html | title = F-16XL | first = Joseph 'Joe' | last = Baugher | publisher = ATT | url-status = dead | archive-url = https://web.archive.org/web/20081006151517/http://home.att.net/~jbaugher4/f16_29.html | archive-date = 2008-10-06 }}

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Category:Tailless delta-wing aircraft

F-16XL

Category:NASA aircraft

General Dynamics F-16XL

Category:Single-engined jet aircraft

Category:Relaxed-stability aircraft

Category:Aircraft first flown in 1982

Category:Mid-wing aircraft

Category:Aircraft with retractable tricycle landing gear