Article Summary and Key Points: The F-16XL was a revolutionary fighter variant with a delta-wing design that doubled its fuel capacity, extended range by 50%, and carried twice the weapons of a standard F-16.
-Entered into the U.S. Air Force’s Enhanced Tactical Fighter competition in the early 1980s, the F-16XL lost to the F-15E Strike Eagle.
-Despite its advanced aerodynamics and increased payload capacity, only two prototypes were ever built.
-They were later used by NASA for supersonic shock wave studies.
-While the F-16XL never entered production, its innovative design demonstrated remarkable fighter/attack potential, marking it as one of aviation’s greatest missed opportunities.
The F-16XL: The Revolutionary Fighter the U.S. Air Force Rejected
The F-16 has always been one of the easiest aircraft to identify, and it isn’t a surprise. The recognizable features include the bubble canopy and the sizeable yawing air intake.
They have been around for over 40 years, and the US has built over 4,600. About 2,600 of them remain in service for the US Air Force.
But the F-16XL was different. And only two of those were ever built.
Meet The F-16XL
Only two F-16XLs were ever made. In 1981, the fighter entered the Air Force’s Enhanced Tactical Fighter (ETF) competition to select a replacement for the F-111 Aardvark.
The F-16XL lost the bid, and the F-15 Eagle ultimately won the ETF competition, joined the US Air Force, and has been mass-produced to become one of the most successful fighter aircraft in Air Force history.
LTG Lawrence A. Skantze spoke when the first F-16XL rolled out on July 2, 1982. At the time, he was the Commander of the Aeronautical Systems Division. He characterized ASD’s perspective as having “one foot in the present and one foot in the future.” And he was spot on.
General Skantze said that “somewhere out there is a new and advanced technology fighter,” and that sometime soon, USAF’s present exploratory work would lead to the definition of that new aircraft. In the meantime, he said, it’s “our responsibility to take the fighter craft we have today and evolve those into higher performers, better performers, and improve their margin and hone the edge of their cutting abilities as the future goes before us.”
The F-16XL could attain a 5G turn in 0.8 seconds, half the time of an F-16A. A 9G turn took just a tad longer. The XL design incorporates a “cranked-arrow” wing to a fifty-six-inch longer fuselage. The cranked-arrow design retains the advantages of delta wings for high-speed flight. Still, the usual disadvantages were rectified by having its aft portion less highly swept than the forward section. It thus retains excellent low-speed characteristics and minimizes the trim drag penalties of a tailless delta.
The larger delta-wing design had more than double the wing area of the standard F-16 (633 square feet vs. 300 square feet), so the drag was reduced.
However, the longer-winged F-16XL could carry more fuel and more weapons. The enlarged wing allowed the new F-16 to store 65 percent more fuel, resulting in a 50 percent further range.
The massive delta wing allowed for more external hardpoints and, hence, larger weapons payloads. The result was a jet that could deploy more weapons than its predecessors and go further to deploy them. And that marked a significant practical improvement over the F-16.
The XL had 17 hardpoints with a capacity of up to 15,000 pounds of payload (stations 2–5 and 13–16 were split into groups, similar to the F-15E). It carried double the armaments of an F-16. It had a 20 mm M61 Vulcan rotary cannon.
The XL was powered by the General Electric F110-GE-100 turbofan, 17,100 lbf thrust dry, 28,900 lbf with afterburner. Top speed was Mach 2.0. It had a climb rate of 62,000 feet per minute.
The Air Force Picked the F-15
Although the USAF chose the F-15, they could have chosen to build some more of the F-16XLs as they would have made great fighter/attack aircraft. But it was not to be. General Dynamics donated the two F-16XLs to NASA.
The F-16XLs were used at Edwards Air Force Base in California in 1988. The idea was to study air flow around the wings, leading them to research how the F-16XL could accelerate to top speed.
One of the tests included a 1995 sonic boom study, in which F-16XL #849 flew 200 feet behind a NASA SR-71 to probe the boundary of the SR-71’s supersonic shock wave. These tests measured and recorded the shape and intensity of the shock waves.
Those studies helped NASA’s High-Speed Civil Transport (HSCT) program engineers to better understand supersonic shock waves in order to reduce sonic boom intensity near populated areas.
Now, the two aircraft are museum pieces; they were outstanding aircraft.
F-16XL: A Story in Photos
F-16XL. Image Credit: Creative Commons.
On October 5, 1993, Langley’s F-16XL High Lift jet was rolled out with a dynamic yellow and black paint job for Aero-Dynamic Flow Studies in High Speed Research.
F-16XL. Image Credit: Creative Commons.
F-16XL. Image Credit: NASA.
Image of what would have been the F-16XL, an artist rendering. Image Credit: Creative Commons.
Image: Creative Commons.
About the Author: Steve Balestrieri
Steve Balestrieri is a 19FortyFive National Security Columnist. He served as a US Army Special Forces NCO and Warrant Officer. In addition to writing for 19FortyFive, he covers the NFL for PatsFans.com and is a member of the Pro Football Writers of America (PFWA). His work was regularly featured in many military publications.
