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 entered the United States Air Force's (USAF) Enhanced Tactical Fighter (ETF) competition in 1981 but lost to the F-15E Strike Eagle. The two prototypes were shelved until being turned over to NASA for additional aeronautical research in 1988. Both aircraft were fully retired in 2009 and stored at Edwards Air Force Base; one of the two aircraft has since been placed on display.

Shortly after winning the lightweight fighter program, General Dynamics Fort Worth began investigating possible F-16 derivatives with the goal of enhancing both air-to-air and air-to-ground mission capabilities while retaining parts commonality with the F-16A. Under the leadership of Harry Hillaker (designer of the original 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) was pursued due to its much more efficient lift-to-drag ratio at supersonic speeds.

The company worked closely with NASA's Langley Research Center and invested significant R&D funds for wind tunnel testing. Over several years the design was refined which led to the final F-16XL design by late 1980.

In 1980, the USAF signed on as a partner, providing the fuselages of the third and fifth production F-16s for conversion. These two fuselages became the only examples of the F-16XL.

In March 1981, the USAF announced the Enhanced Tactical Fighter (ETF) program to procure a replacement for the F-111 Aardvark. 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 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 F-15E required very few alterations from its base F-15B or D, while the F-16XL had major structural and aerodynamic differences from the original F-16. As such, the F-16XL would have required much more effort, time, and money to put into full production. Additionally, the F-15E had two engines, which gave it a much higher maximum takeoff weight and redundancy in the case of engine failure.

In February 1984, the USAF awarded the ETF contract to McDonnell Douglas. The two F-16XLs were returned to the Air Force and placed in storage at Edwards Air Force Base. Had General Dynamics won the competition, the F-16XL would have gone into production as the F-16E/F (E for single seat, F for two seats).

The wing and rear horizontal control surfaces of the base F-16A were replaced with a cranked-arrow delta wing 115% larger than the original wing. Extensive use of graphite-bismaleimide composites allowed the savings of 595 pounds (270 kg) of weight, but the F-16XL-1 and XL-2 were 4,100 pounds (1,900 kg) and 5,600 pounds (2,500 kg) heavier respectively than the original F-16A.

Less noticeable is that the fuselage was lengthened by 56 inches (140 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°, and the ventral fins removed, to prevent them from striking the pavement during takeoff and landing. The F-16XL-2 also received a larger inlet which would go on to be included in later F-16 variants.