Experimental Aerodynamics on Rolling Delta Wings at High Angles of Attack

Normal force and rolling moment acting on delta wings under forced roll oscillation are measured in a low speed wind tunnel. Results for two wings, one with 14 degree apex half angle and the other one with 7 degree apex half angle are compared with flow visualization. Large hysteresis in normal force and rolling moment. is observed even at very slow roll rates. At higher roll rate, positive energy supply from free stream to roll oscillating wings is confirmed. Reduction of stabilizing moment as well as normal Force with the leeward vortex lift-off is shown. At high angle of attack, splitting of lifted-off leeward vortex into one attached and the other one merging into the third vortex from apex is observed on the 7 degree apex half angle model.