General Dynamics F-16XL

The General Dynamics F-16XL is a derivative of the F-16 Fighting Falcon, with a cranked-arrow delta wing. It was originally conceived as a technology demonstrator, later entered in the United States Air Force's (USAF) Enhanced Tactical Fighter (ETF) competition but lost to the F-15E Strike Eagle. Several years after the prototypes were shelved, they were turned over to NASA for additional aeronautical research.


General Dynamics F-16XL
Class Aircraft
Type Fighter
Manufacturer General Dynamics
Origin United States of America
Country Name Origin Year
United States of America 1982
Country Name Operational Year Retirement Year
United States of America View
ManufacturerName Production From Production To Quantity
General Dynamics 2 View

The wing and rear horizontal control surfaces were replaced with a cranked-arrow delta wing 120% larger than the original wing. Extensive use of carbon fiber composites allowed the savings of 600 lb (270 kg) of weight but the F-16XL was still 2,800 lb (1,300 kg) heavier than the original F-16A.

Less noticeable is that the fuselage was lengthened by 56 in (1.4 m) 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°, and the ventral fins removed, to prevent them from striking the pavement during takeoff and landing. However, as the F-16XL exhibits greater stability than the native F-16, these changes were not detrimental to the handling of the aircraft.

These changes resulted in a 25% improvement in maximum lift-to-drag ratio in supersonic flight and 11% in subsonic flight, and a plane that reportedly handled much more smoothly at high speeds and low altitudes. The enlargements increased fuel capacity by 82%. The F-16XL could carry twice the ordnance of the F-16 and deliver it 40% farther. The enlarged wing allowed a total of 27 hardpoints:

  • 16 wing stations of capacity 750 lb (340 kg) each
  • 4 semi-recessed AIM-120 AMRAAM stations under fuselage
  • 2 wingtip stations
  • 1 centerline station
  • 2 wing "heavy/wet" stations
  • 2 chin LANTIRN stations
  • However, the "heavy/wet" stations interfered with up to four wing stations.

NASA testing

In 1988, the two aircraft were taken out of storage and turned over to NASA for research. The first aircraft was fitted with an active suction titanium glove encasing the left wing and delivered to the Ames-Dryden Flight Research Facility at Edwards AFB. Designed and built by North American Aviation (a division of Rockwell International), the glove had laser-cut holes that were nominally 0.0025 in (0.0635 mm) diameter. Distance between holes varied between 0.010 and 0.055 in (0.25 and 1.40 mm) depending on the suction. The glove covered over 5 ft² (0.5 m²) of the wing. It was intended to suck away turbulent airflow over the wing, restoring laminar flow and reducing drag. The aircraft was also involved in testing sonic boom characteristics, takeoff performance, and engine noise, for NASA's civil transport program.

The second aircraft (a two-seater) had its experimental engine replaced with a General Electric F110-129. It accidentally achieved supercruise, a design goal of the F-16XL that was never attained in ETF testing, when it reached Mach 1.1 at 20,000 ft (6,096 m) on full military power. It was mounted with a passive fiberglass and foam glove on the right wing to examine supersonic flow, and an active glove on the left wing. This second glove was composed of fiberglass and foam over a titanium skin, and covers 75% of the wing's surface and 60% of its leading edge. The active portion consists the middle two-thirds of the glove, with laser-drilled holes leading to cavities beneath the wing. It was designed collaboratively by Langley research center, Dryden, Rockwell, Boeing, and McDonnell Douglas. The glove is intended as a testbed for supersonic laminar flow.

The F-16XL flight project office was located at the NASA Dryden Flight Research Center, Edwards AFB, CA. The NASA Langley Research Center, developed and coordinated F-16XL experiments.

At the conclusion of their test programs in 1999, both F-16XLs were placed into storage at NASA Dryden. In 2007, NASA approached Lockheed Martin to request a study into the feasibility and cost of returning F-16XL #1 to flight status and upgrading it with many of the improvements found in the USAF's F-16 Block 40. This was studied while F-16XL #1 was taxi tested at Dryden and given systems checks. However, both F-16XLs were retired in 2009 and stored at Edwards AFB.

Role Experimental fighter
Manufacturer General Dynamics
First flight 3 July 1982
Primary users United States Air Force
NASA
Number built 2
Developed from General Dynamics F-16 Fighting Falcon


General characteristics

  • Crew: One (XL #1) or Two (XL #2)
  • Length: 54?ft 2?in (16.51?m)
  • Wingspan: 34?ft 3?in (10.44?m)
  • Height: 17?ft 7?in (5.36?m)
  • Wing area: 646?ft² (60.0?m²)
  • Empty weight: 22,000?lb (9,980?kg)
  • Loaded weight: 48,000 lb (21,800 kg)
  • Max. takeoff weight: 48,000 lb (21,800 kg)
  • Powerplant: 1 × General Electric F110-GE-100 turbofan
  • Dry thrust: 17,100 lbf (76.3 kN)
  • Thrust with afterburner: 28,900 lbf (125?kN)

Performance

  • Maximum speed: Mach 2.05 (1,400?mph, 698?m/s)
  • Cruise speed: 600?mph (268?m/s)
  • Range: 2,480?nmi (2,850?mi, 4,590?km)
  • Service ceiling: 50,000?ft (15,000?m)
  • Rate of climb: 62,000?ft/min (320?m/s)

Armament

  • Guns: 1 × 20?mm (0.79?in) M61 Vulcan (Gatling) gun
  • Hardpoints: 17 pylons with a capacity of up to 15,000?lb (6,800?kg) of payload

End notes