Forebody Vortex Manipulation for Aerodynamic Control of Aircraft at High Angles of Attack 892220

Control of forebody vortices on fighter aircraft to generate yawing moments at high angles of attack has been investigated with wind tunnel tests on a generic fighter model. Simultaneous force and moment measurements on the complete configuration and the isolated forebody were obtained. Individually controlled tip strakes and pneumatic surface jets were both evaluated. The magnitude and direction of the yawing moment can be controlled by regulating the asymmetric deployment of the strakes or by differential blowing rates from the jets. Various strake sizes and locations were investigated. Strakes at 105° from windward were very effective for eliminating naturally asymmetric vortices and generating controllable yawing moments. Blowing jets aligned tangential to the surface in either aft or forward directions at 135° from windward were also very effective. The best method for controlling the yawing moment is to minimize the natural forebody vortex asymmetry with a small pair of tip strakes and utilize blowing to drive the yawing moment away from the symmetric condition.