Longitudinal flight dynamics and control of highly flexible solar UAV

The structure of the wing of High Altitude Long Endurance (HALE) Unmanned Aerial Vehicle (UAV) is highly flexible, it's deformation of aeroelastics is obvious and coupled with the flight dynamic responses of the UAV, this influent the flight security seriously. In the stage of conceptual design of a solar UAV, in order to estimate the scheme rapidly and accurately, it is necessary to research the characteristics of flight dynamics and control thoroughly. In this paper, the Lagrangian method is employed to model the motion of rigid UAV and the same configuration undergoing static deformation and aeroelastic deformation, the characteristics of flight dynamics and control are compared and it can be found that, while considering the static deformation only, since the pitch moment of inertia become large, the damp and frequency of short period and phugoid are reduced, and the gain of control law should be reduced a little for the same response with rigid UAV. While for elastic UAV, since its phugoid movement is coupled with the aeroelastic movement of wing, the damp and frequency of phugoid increase distinctly, so the gain of control law must be adjust greatly for the same response.