English: This 20-second video from the 1970s shows a purported YF-12C takeoff from Edwards Air Force Base. In actuality, this aircraft was the second production SR-71 Blackbird airframe, serial number 61-7951, which was loaned to NASA under the false number 60-6937 to hide its identity.

The YF-12 "Blackbird" was an experimental fighter-interceptor version of the Lockheed A-12 aircraft. In Air Force flight tests on May 1, 1965, the YF-12 set a speed record of 2,070.101 miles per hour and an altitude record of 80,258 feet. First publicly displayed at Edwards Air Force Base, CA, in 1964, the YF-12 was never adopted by the military as an operational aircraft. It was, however, a precursor to the SR-71 Blackbird reconnaissance plane.

Two YF-12 aircraft were flown in a joint Air Force-NASA research program at the NASA Flight Research Center (now the NASA Armstrong Flight Research Center) between 1969 and 1979, although the second plane, piloted primarily by the Air Force, was lost to an inflight fire in 1971. The two YF-12 aircraft bore the serial numbers 60-6935 and 60-6936.