Republic XF-91 Thunderceptor Please note: This aircraft is in storage. Originally conceived in the mid-1940s as an interceptor, the XF-91 was America’s first rocket-powered fighter to fly faster than the speed of sound. The Thunderceptor’s rocket engine supplemented its main turbojet engine, greatly increasing the aircraft’s speed and climb rate. With its afterburning turbojet and rocket engine in operation, the XF-91 possessed a remarkable climb rate of nearly 30,000 feet per minute. Republic built two prototype XF-91s -- the museum’s aircraft was the first one built, and it first flew in May 1949. Although the F-91 fighter program was canceled due to lack of funding, the prototypes were extensively tested and modified. The Museum’s XF-91, the only remaining example, was transferred from Edwards AFB, Calif., in 1955. TECHNICAL NOTES: Engines: General Electric J47 of 6,700 lbs. thrust with afterburner and Reaction Motors rocket of 6,000 lbs. thrust Maximum speed: 984 mph Cruising speed: 560 mph Service ceiling: 48,700 feet Weight: 28,300 lbs. loaded Click here to return to the Research & Development Gallery. Note: The appearance of hyperlinks does not constitute endorsement by the National Museum of the USAF, the U.S. Air Force, or the Department of Defense, of the external website, or the information, products or services contained therein.