The AD-1 (Ames-Dryden One) is arguably NASA’s strangest looking aircraft. She was a collaborative effort between the Ames and Dryden (now Armstrong) research centers to explore a new concept variable geometry wing. Changing the geometry of a wing in flight makes an aircraft operate more efficiently at a wider range of speeds. Variable geometry wings have been successfully deployed on many aircraft like the Grumman F-14 Tomcat in a variable-sweep, or swing wing configuration. The swing wing design requires complicated, heavy mechanisms with many moving parts which decreases reliability and increases maintenance cost and time. Instead of a swing wing, the AD-1 uses an oblique wing design, rotating its entire wing with a light, simple mechanism.
She was designed by the Rutan Aircraft Company in Mojave, California and built by The Ames Industrial Company in Bohemia, New York, making the first and only manned oblique wing aircraft. The AD-1 first took to the air over NASA Dryden Flight Research Center on December 21, 1979, piloted by Thomas C. McMurtry. NASA pilots gradually increased the rotation angle of the wing up to 60 degrees over the course of the program. This exposed strange flying characteristics which coupled roll and pitch because of its asymmetric design. This could easily be solved in future aircraft using digital stability augmentation systems. McMurty flew the last flight of the program on August 7, 1982 at the Experimental Aircraft Association Annual Convention in Oshkosh, Wisconsin. Now, she hangs in Hiller Aviation Museum in San Carlos, California.