Multiple time scale analysis of aircraft longitudinal dynamics with aerodynamic vectoring

The paper analyzes the longitudinal dynamics of sustained high angle-of-attack flights performed by a small agile Unmanned Aerial Vehicle (UAV) equipped with an aerodynamic vectoring feature. This unique feature is achieved through variable-incidence wing that allows the angle of incidence of the wing with respect to fuselage to be decoupled. The aerodynamics of the UAV is estimated through wind-tunnel experiments. Subsequently, the dynamics of the UAV motion are studied for trim conditions across the complete spectrum of velocity between hover and forward cruise flight. The short-period eigenvalue migration, as the trimmed flight conditions are changed, studied, and the peculiarities observed from this linear analysis are highlighted. Further, the Multiple Time Scales method in conjunction with bifurcation theory is used to obtain the approximate solutions of the multiple degree-of-freedom nonlinear equations of motion. The explicit analytical results obtained are useful to identify the key parameters affecting the dynamics and stability of the aircraft??s longitudinal motion. The conditions leading to limit cycle responses in the vicinity of the stall regime are also highlighted.