Investigation of longitudinal stability analysis of general aviation aircraft by phase plane method

This paper describes using phase plane analysis to investigate the short-period longitudinal stability of a general aviation aircraft during take-off and landing phases. Firstly, the aerodynamic coefficients and characteristics of the aircraft in take-off and landing configurations are analyzed. What is more, considering the effects of deploying flaps during take-off and landing, a second-order short-period modal equation is constructed to evaluate the pitch stability of the aircraft. The stability criterion for the system is also provided. Finally, phase plane analysis is performed on 3 Cases, and the phase trajectory and equilibrium points of the system under 8 different combinations of flight surfaces are obtained. The results show that the deployment of flaps during take-off and landing affects the longitudinal stability of the aircraft, and also some unstable regions that could affect flight safety are predicted.