Summary: As the F-16 Fighting Falcon prepares for a new role in the Russia-Ukraine conflict, its storied past in the U.S. military comes into focus. Over forty years, the F-16 evolved through numerous variants to remain relevant. Among these was the F-16XL, a prototype designed in the early 1980s with enhanced payload and range.

-Despite its advanced capabilities, the F-16XL lost out to the F-15E due to budget and complexity concerns.

-The two F-16XL prototypes ended up in NASA’s research programs. Though never deployed, the F-16XL's innovative design remains a respected chapter in aviation history.

F-16XL: The Prototype That Redefined Fighter Jet Capabilities

As the F-16 Fighting Falcon continues to make headlines for its imminent role in the ongoing Russia-Ukraine war, a look back at the platform’s aerial contributions to the U.S. military is timely. The American-made supersonic multirole fighter aircraft has served the Air Force for more than forty years, providing key capabilities along the way.

As new technologies have emerged over time, an array of F-16 variants were developed in order to ensure the platform’s relevance in a changing threat environment.

While these subtypes are all unique, some never made it past the prototype phase—including the F-16XL.

Introducing the F-16 Fighting Falcon family of fighters

Designed to answer the lessons learned during the Vietnam War, the F-16 was conceptualized to fulfill America’s need for more air superiority fighter platforms. The “Fighter Mafia,” spearheaded by renowned Colonel John Boyd in the late 1960s, secured Department of Defense funding to make this concept a reality.

However, some Air Force officials were not pleased with the emergence of a new fighter theory since they believed it could threaten the service’s own F-15 Eagle program. In the end, the Air Force adopted the Lightweight Fighter proposal, leading to the prototype which would grow to become the YF-16.

Shortly after manufacturer General Dynamics was awarded the Lightweight Fighter program contract, the manufacturer began brainstorming subsequent variants equipped with improved air-to-air and air-to-ground capabilities. Around this time in the early 1980s, the service announced the creation of the Enhanced Tactical Fighter program in an effort to secure a replacement platform for the F-111 Aardvark.

The Air Force specifically was seeking a jet able to launch deep interdiction missions without needing additional support via jamming measures or fighting escorts. In response, General Dynamics submitted its proposal for the F-16XL variant, while McDonnell Douglas submitted its design plans for a new F-15 Eagle variant. While the F-15E was meant to be largely derived from its sister variant, the F-16XL would have required much more time, effort, and funds to build.

Due in part to budgetary constraints and the desire to avoid complications that would have come with creating essentially a new fighter, the Air Force awarded the ETF contract to McDonnell Douglas. The pair of F-16XL prototypes developed by General Dynamics were returned to service and ultimately relegated to storage duty at Edwards Air Force Base.

The F-16XL: Proposed specs & capabilities

Before the prototype was nixed, the chief project manager for the F-16XL variant, Harry J. Hillaker, revealed that the new variant sported enhanced payload and range capabilities. Notably, the fighter was designed to be able to carry twice the payload of its F-16 predecessor and travel up to 44 percent farther without the need for external fuel tanks.

In other words, the fighter was able to fly farther while still carrying four Advanced Medium-Range Air-to-Air Missiles and a pair of Sidewinder AIM-9 infrared missiles. With this payload, the airframe’s missile radius could be nearly doubled.

As detailed by Air and Space Forces, “As for penetration and survivability, the F-16XL can dash supersonically with a load of bombs at either high or low altitude. It can climb at high rates with the bombs aboard. And it has a speed advantage of up to eighty-three knots over the F-16A at sea level at military power setting and 311 knots on afterburner at altitude while carrying a bomb load.” In terms of size, the wing and rear horizontal control surfaces of the proposed variant were replaced with a delta wing more than 1,100 times the size of the original wing. Additionally, the F-16XL’s fuselage measured roughly 56 inches longer than its predecessor due to the inclusion of two sections at the joints of the main fuselage sub-assemblies.

Despite these key capabilities, the F-16XL was passed for the F-15E Eagle. However, two of these prototypes referred to by their serial numbers (#849 and #848) were first moved to NASA’s Langley Research Center, where they participated in an array of experiments that would continue until the late 1990s.

Interestingly, #849 was used in a sonic boom study where it successfully flew just a couple hundred feet behind an SR-71 Blackbird to determine the boundary of the platform’s supersonic shockwave.

The F-16XL may have never made it to the frontlines of the Air Force, but the formidable variant remains well respected by aviation experts.

About the Author: Maya Carlin 

Maya Carlin, National Security Writer with The National Interest, is an analyst with the Center for Security Policy and a former Anna Sobol Levy Fellow at IDC Herzliya in Israel. She has by-lines in many publications, including The National Interest, Jerusalem Post, and Times of Israel. You can follow her on Twitter: @MayaCarlin.