The F-16XL is a lesser-known but highly advanced derivative of the iconic F-16, showing testimony to the innovative spirit behind military aviation. It features a quite distinct cranked arrow delta wing and an overall stretched prototype ordered specially to test the probabilities for supersonic cruise speed. Over time, this would find its way to evolve into a fighter aircraft and then become a test-bed for the U.S. Air Force and NASA.
In February 1980, General Dynamics proposed a radical modification of the F-16 fighter to achieve supersonic cruise speed; the SCAMP was born. The primary purpose was to establish whether or not a cranked-arrow-shaped delta wing—having an area greater than twice that of a standard F-16 wing—was going to provide low drag at supersonic velocities without reducing maneuverability at low speeds.
A contract was subsequently signed with the USAF in late 1980, under which General Dynamics purchased two FSD F-16As, while two more were supplied by the Air Force for modification.
The F-16XL spanned 54 feet and 2 inches, and measured 17 feet and 7 inches high, with an empty weight of 22,000 pounds and a maximum takeoff weight of 48,000 pounds. There were two variants built: the single-seat F-16XL-1 and the twin-seat F-16XL-2. This did so by lengthening the fuselage by two new sections so as to raise the tail 3 degrees, not to have the engine nozzle strike the runway during takeoff and landing.
It was made of carbon composite material; its surface area was 120% larger than that of an F-16, with swept angles ranging from 50 to 70 degrees. This design gave the F-16XL an increase in fuel-carrying capacity by 82%, making it among the long-range and heavy-payload-carrying aircraft. It could be armed with a single 20-mm M61A1 cannon, AIM-9 Sidewinder missiles, and up to 15,000 pounds of ordnance externally, carried on 17 hard points.
The single-seat F-16XL-1, powered by a single F100-PW-200 turbofan, flew for the first time on 3 July 1982 after more than 3,600 hours of wind tunnel test, and a twin-seat F-16XL-2, powered by the 110-GE-129 engine, took to the air on 29 October 1982. This aircraft had much greater abilities than the F-16XL; it was able to fly at supersonic speed with a full load of bombs, and throughout Mach 0.96 at 26,000 feet, it was 83 knots faster than the F-16A. Bittick climbed into the cockpit of the single-seat F-16XL 1 and lit the burners; at approximately 20,000 feet, he saw the needle of the machometer inch its way rightward, passing Mach 1.00—the speed of sound—without so much as a shudder.
The USAF initiated a search in March 1981 for a next-generation, high-performance tactical fighter, with the requirement to replace the aging F-111. General Dynamics offered both F-16XLs in the competition against a tandem-seat variant of the McDonnell Douglas’ F-15B Eagle. Although the F-16XL easily outclassed the F-15B Eagle in range, payload, and stability, the latter was selected due to the preference for a twin-engine configuration with more powerful thrust and lower production cost. Both F-16XLs were stored in 1985.
In the autumn of 1988, NASA modified the Fs-16XLs as a testbed for aerodynamic research at supersonic speeds. An experimental titanium segment, a kind of ‘glove’ reducing drag and fuel consumption, was fitted to the F-16XL-1; this prototype flew a range of supersonic evaluations and then took part in tests studying takeoff performance and engine noise reduction.
From 1991 to 1992, the F-16XL-2 was refitted with a General Electric F110-129 engine and fitted with both ‘passive’ and ‘active’ gloves for studies on aerodynamic fluid mechanics. With some minor problems, the F-16XL-2 flew 45 times.
After the project ended in 1999, both F-16XLs were put into storage until 2007, when NASA briefly considered bringing one back to operational status. Today, one F-16XL remains stored while another is on display at the Air Force Flight Center Museum at Edwards.
The F-16XL, although overshadowed by its contemporaries, still is an outstanding achievement in aeronautical innovation and an important part of military aviation history.