1997 年 45 巻 519 号 p. 222-230
Unsteady aerodynamic characteristics of rolling delta wings were investigated by measuring normal forces and rolling moments acting on delta wing models of 14 and 7 degree apex half angles, which are forced to oscillate sinusoidally in roll. The experiment was conducted in a low-speed wind tunnel at several roll frequencies. Vortex breakdown is observed in more limited range of one roll cycle in forced oscillation than in static test, therefore, normal force and restoring rolling moment increase with applying roll oscillation. With increasing the roll rate, energy is supplied from rolling wings to free stream at low angles of attack, but energy is supplied from free stream to rolling wings at higher angle of attack, which will result in wing rock. The effects on wing rock of roll damping, the convective time lag in separated vortex movements and the time lag in vortex breakdown are also discussed in relation to the direction of roll hysteresis curves.