Influence of aerodynamic parameters on short-period mode characteristics of closed-loop aircraft

Owing to the relaxed static stability technology applied to the modern high-performance fighter aircraft, the design of an advanced flight control system is required to confirm its closed-loop system for an excellent dynamic property within the flight envelope. The ability of flight control system (FCS) is limited as a result of the control effectiveness and deflection rate of the control surface. The designed aerodynamic parameters of aircraft must meet certain requirements to confirm good flying qualities in its closed-loop system. This paper presents a new method which describes the influence of various aerodynamic parameters on short-period mode characteristics of closed-loop aircraft. A relaxed static stability aircraft with model reference dynamic inversion control law is provided to investigate the influence rules of various aerodynamic parameters on short-period mode characteristics based on the equivalent parameter criterion. The results show that the elevator control effectiveness has a great influence on the short-period mode characteristics and the aerodynamic parameters need to match a certain match value set to keep excellent short-period mode flying qualities. The proposed method can provide reference for flight control system design with the optimized aerodynamic parameters for relaxed static stability aircraft.