Sierra Sue

Built in 1953, the Sierra Sue was Northrop Company’s flying demonstrator for the Air Force’s AX close-support aircraft design competition in 1972. The AX Competition led to the manufacture of two prototypes, Northrop’s A-9A and Fairchild-Hiller’s A-10A. After an extensive flight test program, the Fairchild-Hiller design won the competition.

Designed and flown by Ron  Beattie and Walt Fellers, the aircraft was manufactured by Acme's (Sierradyne Inc.) Crawford and Keeney.  It was used by Sierradyne in the '60s to test and promote Northrop's and Dr Werner Pfenninger's boundary layer control concepts. The plane was never officially considered a Northrop aircraft.

                          Northrop’s A-9A concept aircraft