NASA operations

In 1967, a deal was struck between NASA and the Air Force whereby the former was given access to early A‑12 wind tunnel data in exchange for NASA providing a small team of skilled engineers to work on the SR‑71 flight‑test program. NASA signed a memorandum of understanding with the Air Force on June 5, 1969, which permitted them access to the two remaining YF‑12As then in storage. Phase one of the program was controlled throughout by the Air Force and got underway at Edwards AFB on December 11, 1969, utilizing YF‑12A 60‑6936. Essentially this phase consisted of developing possible bomber penetration tactics against an interceptor with the YF‑12’s capabilities. It terminated on June 24, 1971, after the aircraft caught fire during the closing stages of the 63rd flight, whilst on base‑leg at Edwards AFB. Fortunately both crewmembers safely ejected, but the aircraft crashed and was totally destroyed.

^{A T‑38 chase plane accompanies a YF‑12A whilst serving with NASA. The YF‑12A has an instrumentation package below the fuselage for a series of so‑called “cold wall” experiments. (NASA)}

Whilst the YF‑12As were being readied for flight two, NASA crews were checked‑out by senior Air Force SR‑71 crewmembers. Utilization of the high‑speed platform proved to be high, since NASA engineers at Langley were interested in aerodynamic experiments and testing advanced structures; Lewis Research Establishment wanted to study propulsion, whilst Ames Research Center concentrated on inlet aerodynamics and the correlation of wind‑tunnel and flight‑test data. In addition, the aircraft was used to support various specialized experimentation packages.

Ultimately, 60‑6935 continued operating until the program ceased after its 145th NASA flight on October 31, 1979. A week later an Air Force crew ferried the aircraft to the Air Force Museum (now the National Museum of the US Air Force) at Dayton, Ohio, where it is displayed as the sole surviving example of the YF‑12A.