The AD-1 oblique wing aircraft built in 1979 by Ames Industrial for NASA. The AD-1 could pivot its entire wingspan from zero to 60 degrees during flight. Wind tunnel tests on scale models showed that the oblique wing configuration reduced aerodynamic drag at high speeds. This allowed the plane to increase speed and travel longer distances while decreasing fuel consumption. During manned test flights, the AD-1 demonstrated instability at certain wing angles. The project ended in 1982.