The Lockheed YF-12 was an interceptor that could go high and fast, Mach 3, to defend against supersonic bombers developed in the 1960s. Derived from the A-12 reconnaissance aircraft, YF-12A led to the SR-71 Blackbird strategic reconnaissance aircraft. For years to come, it would remain the standard bearer for American aeronautical prowess.
The first flight of the YF-12 program was in August 1963, and three prototypes were built. By May 1965, the first and third YF-12s established numerous world speed and altitude records, which included a world speed record of 2,070.101 mph and a world altitude record of 80,257.65 feet. These records were flown by Col. Robert L. “Fox” Stephens and Lt. Col. Daniel Andre in the record-setting aircraft, for which they earned the 1965 Thompson Trophy.
The YF-12 program was canceled in early 1968. The reasons were threefold: first, the program was so expensive; secondly, the furious argument raging over Southeast Asia; and lastly, changing air defense priorities at home. In 1969, the second YF-12A was taken back from storage for a joint USAF/NASA study to research supersonic cruise technology and is now on display at the National Museum of the United States Air Force. It was the last remaining YF-12A; the first had been irreparably damaged in a landing mishap, and the third was scrapped following an in-flight fire.
The YF-12 was armed with three Hughes AIM-47A missiles and powered by two Pratt & Whitney J58 engines of 32,000 lbs. thrust with an afterburner. It was capable of speeds over Mach 3; its range was well more than 2,000 miles, and it could fly above 80,000 feet.
In the 1990s, NASA flew three SR-71 aircraft: two SR-71A models and an SR-71B pilot trainer, for high-speed and high-altitude research. Based at NASA’s Dryden Flight Research Center at Edwards, California, the aircraft were transferred from the U.S. Air Force following the cancellation of their program. The ability to cruise at Mach 3 for more than one hour made the SR-71 an extremely useful platform for many research topics, which included aerodynamics, propulsion, and atmospheric studies.
Notable NASA experiments included a laser air data collection system that gathered airspeed and attitude reference data using laser light instead of air pressure. Another major program was the Linear Aerospike Rocket Engine or LASER experiment. The SR-71 also was used as a science camera platform for NASA’s Jet Propulsion Laboratory to study celestial objects in ultraviolet wavelengths.
Among others, the operational record of the YF-12 includes setting a speed record of 2,070.101 mph and an altitude record of 80,257.86 feet on May 1, 1965. Its special weapon system showed great promise; it fired six AIM-47 missiles and registered very positive results. However, the program was finally scrapped after the production of F-12B was canceled.
The NASA test program was aimed at investigating several problems associated with high-speed and high-altitude flight. Two of the more important parameters to be investigated were engine inlet performance and heat transfer under high-Mach conditions. Although two YF-12As were lost in accidents, the remaining aircraft continued to provide data of inestimable worth for both the USAF and NASA.
Part of its legacy is retained through its contributions to research into supersonic flight and in the making of the SR-71 Blackbird, still today the fastest and highest-flying production aircraft in the world. The only surviving YF-12A now hangs on display at the National Museum of the United States Air Force and pays homage to the pioneering spirit of innovation in aviation.