Active control of wing rock using tangential leading-edge blowing

Experiments were performed to demonstrate positive poststall roll control of a free-to-roll wind-tunnel delta wing model using tangential leading-edge blowing. Previous static experiments had shown that significant rolling moments could be produced up to an angle of attack of 55 deg using asymmetric tangential leading-edge blowing. The implication was that poststall dynamic roll control ought to be possible using only blowing. To demonstrate experimentally that this was indeed the case, a free-to-roll wind-tunnel model sting mounting system and a pair of fast acting blowing control servo-valves were developed and manufactured. An automatic feedback roll control algorithm using tangential leading-edge blowing was then synthesized and implemented on a digital controller. Results from the present dynamic experiments indicated that with just symmetric blowing alone, wing rock at an angle of attack of 55 deg was damped. Furthermore, with the use of an automatic roll feedback control algorithm employing asymmetric blowing, the same wing rock was stopped in less than one cycle of the limitcycle oscillation.