The comparison of conventional Yaw Axis control versus Closed Loop Yaw Axis control

Abstract

The primary flight control system (PFCS) provides full time and full authority three axis, dynamic control law functions (pitch, roll and yaw) and non-dynamic control law functions (aileron droop, speed brake and ground lift dump). In addition, the PFCS calculates operational and limiting airspeed in order to provide full flight envelope protection across the entire flight envelope. PFCS provides limited gust alleviation function in the yaw axis. This paper provides a high level comparison of conventional Yaw Axis control (Pedal to Surface with Augmentation) versus Closed Loop Yaw Axis control. Pedal to Surface versus Closed Loop design options have implications on a variety of factors including Human Factors, Gust Response, structural limiting requirements, asymmetric thrust response, and rudder trim.