Aerodynamic interceptors efficiency for subsonic missiles roll attitude control

Abstract

The excessive roll of air-launched missiles is a result of disturbances during the flight due to airframe misalignment, asymmetric control in pitch and yaw planes, atmospheric disturbances or large torque disturbances in the vicinity of aircraft. In order to overcome the undesired roll motion effects, most missiles are equipped with the roll autopilots to stabilize their roll attitude in spite of disturbances. In this paper, the classical and optimal control theory are applied in the design of a roll autopilot of the missiles controlled by the aerodynamic interceptors with the roll rate feedback in the inner loop and the roll angle in the outer loop. The desired command is transformed to the aerodynamic interceptor deflection by the pulse width modulation. The efficiency of the roll autopilot is verified on a wind tunnel model mounted on a free rotating adapter which enables movements around the longitudinal axis of the model support system. Based on the wind tunnel model response to the interceptor command, the transfer function of the wind tunnel model is determined. The results of the experiments show the influence of the roll autopilot gains on the wind tunnel model response. The wind tunnel experiments have also shown that missile oscillations occur due to the pulse width modulated deflection of the aerodynamic interceptors.