2000 年 48 巻 560 号 p. 501-506
Dynamic characteristics of a delta wing in pitching motion near ground as well as in an air were investigated experimentally. Its flight attitude can be changed smoothly and periodically by a robot with six degrees of freedom which is controlled by a microcomputer. A ring-shaped force balance to measure lift, drag and pitching moment was also developed in the research, and it could get force and moment within the error of 1. 6%. It is found that the existence of the ground causes a faster stall and increases the maximum lift coefficient over 5. 6% compared with the result out of ground effect. Coefficients of lift, drag and pitching moment plot a 8-shaped hysteresis loop owing to the time lag of leading edge vortex formation. This hysteresis becomes remarkable at such region of high angle of attack as a stall with an ground effect. Derivative of measured pitching moment coefficients with respect to an attack angle indicates that longitudinal static stability increases in the case of ground effect.