English

Noun

unstart ‎(plural unstarts)

1. A sudden compressor stall that can occur in the jet engines of supersonic aircraft.
   • 1988 November, T. A. Heppenheimer, quoting Jim Eastham, “Mach 5 spy plane”, in Popular Science, volume 233, number 5, ISSN 0161-7370, page 114:

     Jim Eastham, one of the original SR-71 test pilots, vividly remembers unstarts: “An unstart demands your full and undivided attention,” he recalls.

   • 1996, Richard H. Graham, “Technical Features of the SR-71”, in SR-71 Revealed: The Inside Story, Zenith Imprint, ISBN 9780760301227, Unstarts and Aerodynamic Disturbances (ADs), page 56:

     An unstart was usually a very unpredictable and violent manoever of the aircraft. […] At altitudes above 75,000 feet, aileron control may in ineffective in controlling the roll during an unstart unless the Angle of Attack is immedicately reduced. the instant an unstart occurs, the pilot's first action is to arrest any pitch-up motion of the aircraft.

   • 2006, National Research Council (U.S.). Steering Committee for the Decadal Survey of Civil Aeronautics,, Decadal Survey of Civil Aeronautics: Foundation for the Future, National Academic Press, ISBN 9780309101585, Appendix A: R&T Challenges for Aerodynamics and Aeroacoustics, page 73:

     At supersonic speeds, adverse interactions between shock waves and boundary layers can increase drag and cause engine unstart.

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