Fixed‐Wing Lateral and Directional Dynamic Stability

Abstract Stability and control are fundamental properties of an aircraft's dynamic characteristics, influencing flying qualities and hence pilot workload and safety. They are closely linked to other fundamental aspects of aircraft design, including aerodynamics, performance, systems, structure, and operating cost factors. This chapter discusses the governing equations of motion for a rigid‐body aircraft and their linearized form, the latter facilitating the decoupling of lateral–directional stability and control from its longitudinal counterparts for conventional aircraft. The consideration of flight responses in terms of their constituent modes of motion is introduced, using the linear state‐space form of the equations and a stability‐and‐control‐derivative representation of the aerodynamic loads. Thereafter, the stability and response associated with each lateral–directional mode is described in some detail for standard aircraft configurations, with reference to the aerodynamic parameters governing the behavior. The chapter concludes with a brief comment on nonlinearity and how it may modify the linear system stability and control characteristics.