In February of 1980, General Dynamics
made a proposal for a Fighting Falcon version with a radically-modified wing shape. The
project was known as SCAMP (Supersonic Cruise and Maneuvering Prototype) and later as
F-16XL. The wing was to be of a cranked-arrow wing shape, with double the area of the
standard F-16 wing. This new wing would, it was hoped, make supersonic cruise performance
possible.
This program was initially funded by the
manufacturer, and involved conversion of two FSD F-16As. In late 1980, the USAF and
General Dynamics agreed to a cooperative test program, with the Air Force providing the
third and sixth FSD F-16s for modification into F-16XL prototypes. The fuselage was
lengthened to 54 feet 1.86 inches, and was fitted with a cranked-arrow wing incorporated
carbon composite materials to save weight. The increased area allowed the incorporation of
up to 17 stores stations. Although the rebuild did involve a modest increase in the length
of the fuselage, the new XL designation did NOT stand for "Xtra Length". I am
not sure what it DID stand for, though.
The first of two F-16XLs (75-0749) had a
single seat and was powered by an F100-PW-201 turbofan. It flew for the first time on July
3, 1982, with James McKinney at the controls. The second F-16XL was originally the third
FSD F-16A (75-0747) which had been damaged in a landing accident. It was fitted with an
F-16B two-seat cockpit. It was powered by a 29,000 lb.s.t. General Electric F110-GE-100
turbofan. It flew for the first time on October 29, 1982, piloted by Alex Wolf and Jim
McKinney. The single-seater is sometimes known as the F-16XL-1, the two-seater as F-16XL-2
The ventral fins of the standard F-16
were not fitted. The absence of ventral fins and the canting of the aft fuselage three
degrees allows greater angles of attack on landing, which decreases the approach speed.
Split airbrakes were fited to either side of the rear jetpipe exhaust, and a drag chute
assembly similar to that fitted to the Norwegian, Belgian, and Venezuelan F-16s was fitted
underneath the vertical fin trailing edge. The drag chute assembly was initially fitted
only to the two-seat F-16XL, but was later retrofitted to the single-seat F-16XL during
NASA service.
The centerline and two inlet stations are
common to the F-16C/D. Four AIM-120 AMRAAM stations are partially submerged in the wing
roots. Four hardpoints with twn stations are underneath each inboard wing panel, and
AIM-9/AIM-120 missile launch rails can be carried at each wingtip.
The handling of the F-16XL was reportedly
quite different from that of the standard F-16, offering a much smoother ride at high
speeds at low altitudes.
In March of 1981, the USAF announced that
it would be developing a new advanced tactical fighter to replace the F-111 in the
low-level, night, and bad-weather interdiction role. Since the F-16XL was already on hand,
General Dynamics entered the F-16XL in the competition, the McDonnell Douglas company
submitting an adaptation of the two-seat F-15B Eagle. In February of 1984, the Air Force
announced that it had selected the McDonnell Douglas design in preference to proposed
production versions of F-16XL. The McDonnell Douglas proposal was later to enter
production as the F-15E Strike Eagle.
Had the F-16XL won the competition,
production aircraft would have been designated F-16E (single-seat) and F-16F (two-seat).
Following the loss of the contract to McDonnell Douglas, General Dynamics returned both
F-16XLs to Fort Worth during the summer of 1985 and placed them in storage. They had made
437 and 361 flights respectively. Although supersonic cruise without afterburner had been
an original goal of the F-16XL program, the aircraft never did quite achieve this feat.
In late 1988, the two prototypes were
taken out of storage and turned over to NASA. They were used in a program designed to
evaluate aerodynamics concepts to improve wing airflow during sustained supersonic flight.
The first F-16XL was reflown on March 9,
1989 and delivered to the Ames-Dryden Flight Research Facility at Edwards AFB. This
aircraft was modified for laminar-flow studies with an experimental titanium section on
its left wing with active suction to siphon off a portion of a layer of turbulent surface
air via millions of tiny laser-cut holes. The first flight with the new wing took place on
May 3, 1990, pilot Steve Ishmael at the controls. This aircraft has been assigned the NASA
number of 849.
The single-seat F16XL was briefly
assigned to the NASA/Langley facility in Virginia from April to November 1994 to evaluate
takeoff performance and engine noise as part of a project to evaluate the configuration of
a possible future high-speed civil transport.
The second F-16XL (75-0747) went to
NASA's Dryden Flight Research Center at Edwards AFB. The aircraft has carried the NASA
number 846 (briefly) and 848. The two-seater has continued with the laminar-flow studies
initiated by the single-seater.
Specification of F-16XL:
Engine: One Pratt & Whitney
F100-PW-200 turbofan, 23,770 pounds with afterburning. Maximum speed: Mach 2.05 at 40,000
feet. Dimensions: wingspan 34 feet 3 inches, length 54 feet 2 inches, height 17 feet 7
inches, wing area 646 square feet. Weights: 43,000 pounds combat, 48,000 pounds maximum
takeoff. Armament: 0ne 20-mm M61A1 cannon. An AIM-9 Sidewinder infrared-homing air-to-air
missile could be carried at each wingtip. An external ordnance load of up to 15,000 pounds
could be carried on up to 17 external hardpoints.
Sources:
- Combat Aircraft F-16, Doug Richardson,
Crescent, 1992.
- General Dynamics Aircraft and their
Predecessors, John Wegg, Naval Institute Press, 1990.
- The American Fighter, Enzo Angelucci and
Peter Bowers, Orion, 1987.
- United States Military Aircraft Since
1909, Gordon Swanborough and Peter M. Bowers, Smithsonian, 1989.
- F-16 Fighting Falcon--A Major Review of
the West's Universal Warplane, Robert F. Dorr, World Airpower Journal, Spring 1991.
- The World's Great Interceptor Aircraft,
Gallery, 1989.
- Modern Military Aircraft--F-16 Viper, Lou
Drendel, Squadron/Signal Publications, 1992.
- Lockheed F-16 Variants, Part 1, World
Airpower Journal, Volume 21, Summer 1995.
- F-16XL--Fighting Falcon in Extra Large
Size, World Airpower Journal, Volume 1, Spring 1990.
