Wind-Tunnel Measurements of Wing-Canard Interference and a Comparison with Various Theories

CANARD-CONFIGURED AIRCRAFT DESIGNS have played a historic role in aeronautical research. However, only in the past decade or two has a canard been incorporated into a significant number of aircraft designs. Powered flight began with the Wright Flyer, which was a canard-configured aircraft. Unfortunately, however, that aircraft was longitudinally unstable and the misconception arose that all canard aircraft would be unstable in pitch, irrespective of the placement of the center of gravity. In the early years of aircraft development, the canard concept was dropped in favor of conventional tailaft designs. It was not until the 1960s that canards were again seriously considered for several high-speed, designs. For example, in the United States’ supersonic transport program, a canard was initially considered; because of several problems with aerodynamic interference, however, the idea was abandoned. For example, the canard wake passed around the vertical stabilizer and resulted in erratic directional behavior. Canard tip vortices