Developed for the USAF as reconnaissance aircraft more than 30 years ago, SR-71s were the world's fastest and highest-flying production aircraft. The aircraft could fly at speeds of more than 2,200 miles per hour (Mach 3+, or more than three times the speed of sound) and at altitudes of over 85,000 feet.
Dryden had a decade of past experience at sustained speeds above Mach 3. Two YF-12A aircraft and an SR-71 designated as a YF-12C were flown at the center between December 1969 and November 1979 in a joint NASA/USAF program to learn more about the capabilities and limitations of high-speed, high-altitude flight. The YF-12As were prototypes of a planned interceptor aircraft based on a design that later evolved into the SR-71 reconnaissance aircraft.
The two SR-71s at Dryden were assigned the following NASA tail numbers: NASA 844 (A model), military serial 61-7980 and NASA 831 (B model), military serial 61-7956. From 1990 through 1994, Dryden also had another "A" model, NASA 832, military serial 61-7971. This aircraft was returned to the USAF inventory and was the first aircraft reactivated for USAF reconnaissance purposes in 1995. It has since returned to Dryden along with SR-71A 61-7967.
The last SR-71 flight was made on Saturday October 9, 1999, at the Edwards AFB air show. The aircraft used was NASA 844. The aircraft was also scheduled to make a flight the following day, but a fuel leak grounded the aircraft and prevented it from flying again. The NASA SR-71s were then put in flyable storage, where they remained until 2002. They were then sent to museums.