During the early 1960s, the NASA Flight Research Center was involved in support of the national Supersonic Transport Program (SST). Two prototype Mach 3+ high altitude bombers, built by North American Aviation for the Air Force, became available for SST research with the cancellation of their intended military program. The XB-70A Valkyrie was the largest experimental aircraft, measuring 190 feet in length, with a wing span of 105 feet and standing 33 feet in height. The aircraft had a delta wing and hinged wing tip that could be folded down to a 65 degree angle to improve stability at the aircraft's supersonic speeds of up to Mach 3. At this speed the Valkyrie was designed to ride its own shock wave.
