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18 December 1969

 

Speed Equals Stealth

The SR-71 "Blackbird" was designed & developed in secrecy by the Lockheed "Skunk Works" by a team headed by Clarence L. "Kelly" Johnson.  First built as a Mach 3 interceptor for defense against supersonic bombers (the A-12 and YF-12), it was find to be unsuited to the task, but much better as a supersonic high-altitude photographic reconnaissance platform.  Fueled by JP-7, and powered by two Pratt & Whitney J58 Turbojet Engines, the Blackbirds were capable of cruising at Mach 3.2 and attaining altitudes in excess of 80,000 feet.  

The Dryden Flight Research Center's involvement with the YF-12A began in 1967. Ames Research Center in Sunnyvale, California, was interested in using wind tunnel data that had been generated at Ames under extreme secrecy. Also, the Office of Advanced Research and Technology (OART) saw the YF-12A as a means to advance high-speed technology, which would help in designing the Supersonic Transport (SST) that Boeing was designing, and the Air Force needed technical assistance to get the latest reconnaissance version of the A-12 family, the SR-71A, fully operational. Eventually, the Air Force offered NASA the use of two YF-12A aircraft, 60-6935 and 60-6936. A joint NASA-USAF program was mapped out in June 1969.

NASA and Air Force technicians spent three months readying #953 for flight, which first flew in June of 1965. On 11 December 1969, the flight program got underway with a successful maiden flight piloted by Col. Joe Rogers and Maj. Gary Heidelbaugh of the SR-71/F-12 Test Force.  

After some modification were made to this SR-71 #953's Electronic Counter-Measures (ECM) systems, the aircraft was tasked with a test flight to insure the ECM's proper function.  SR-71 #953 was climbing and accelerating after an in-flight refuel over Nevada.  Suddenly, a explosion rocked the nose.  Severe nose pitch up attitude occurred with the nose oscillating from side to side violently even though the pilot had the stick full forward. An irrecoverable high-speed stall resulted. Lt Col Joseph Rogers (Director of the Test Force, and holder of the Absolute Speed Record for a single-engine aircraft) and Reconnaissance Systems Officer (RSO) Lt Col Gary Heidelbaugh both ejected safely.  Falling through the air, the aircraft's fuselage broken into two major pieces, and plowed into the desert north of the remote town of Shoshone, east of Death Valley.

Although the exact cause of this accident was never determined, an obstruction in the pitot static system could have caused a delay in the pressure sensing to the Stability Augmentation System (SAS) and may have been a factor in this accident.

 

 

 

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