Two retired US Air Force F-15 jets have joined the flight research fleet at NASA’s Armstrong Flight Research Center in Edwards, California, USA to support the X-59 quiet supersonic flight test program.
The F-15s will support supersonic research for NASA’s Flight Demonstrations and Capabilities project, which includes the quiet supersonic flight test program (Quesst) mission. One of the aircraft will return to the air as an active NASA research aircraft, while the second will be used for parts to support long-term fleet sustainment.
“These two aircraft will enable successful data collection and chase plane capabilities for the X-59 through the life of the Low Boom Flight Demonstrator project,” said Troy Asher, director for flight operations at NASA Armstrong. “They will also enable us to resume operations with various external partners, including the Department of War and commercial aviation companies.”
The aircraft have been acquired from the Oregon Air National Guard’s 173rd Fighter Wing at Kingsley Field. The two aircraft arrived at NASA Armstrong on December 22, 2025.
“NASA has been flying F-15s since the early 1970s,” Asher said. “Dozens of scientific experiments have been flown over the decades, and NASA’s F-15s have made a significant contribution to aeronautics and high-speed flight research.”
The F-15s allow NASA to operate in high-speed, high-altitude flight testing environments. The aircraft can carry experimental hardware externally under its wings or slung under the center and can be modified to support flight research.
Now that these aircraft have joined NASA’s fleet, the team at Armstrong can modify their software, systems and flight controls to suit mission needs. The F-15’s ground clearance allows researchers to install instruments and experiments that would not fit beneath many other aircraft.
NASA has already been operating two F-15s modified so their pilots can operate safely at up to 60,000ft (18,288m), the top of the flight envelope for the X-59, which will cruise at 55,000ft (16,764m).
The new F-15 that will fly for NASA will receive the same modification, allowing for operations at altitudes most standard aircraft cannot reach. The combination of capability, capacity and adaptability makes the F-15s suited for flight research at NASA Armstrong.
“The priority is for them to successfully support the X-59 through completion of that mission,” Asher said. “And over the longer term, these aircraft will help position NASA to continue supporting advanced aeronautics research and partnerships.”
