Directional control at high angles of attack using blowing through a chined forebody

Abstract

Directional control through the use of pneumatic blowing was investigated on a generic subscale model with a chined forebody. Pneumatic control was accomplished by blowing through a chine slot in a direction normal to the forebody surface. Comparisons are made with a vertical tail on and off, and with control through conventional rudder deflection. Force and moment data were obtained for various blowing coefficients over an angle-of-attack range from 0 to 75 deg to document the techniques effectiveness. Flow visualization was also conducted in order to obtain qualitative information about the effect on the flowfield. Results indicate that pneumatic blowing through a chined forebody can be an effective technique for generating yaw moments at large angles of attack where conventional control surfaces lose their effectiveness. Yaw moments generated are typically much larger than that obtained by just the jet thrust effect alone since the forebody flowfield is significantly modified from the interaction of the jet with the chine vortices. Directional control capability was found to increase with angle of attack for a given blowing coefficient until a maximum was reached. Further increases in angle of attack result in a rather rapid loss of effectiveness. In addition, the effectiveness of the pneumatic concept was found to be dependent on tail configuration.