Flight dynamics and control in relation to stall

Control of fixed-wing aircraft at high angles of attack is particularly challenging. In this case, aerodynamic forces can be subjected to strong variations, among which stall is certainly the most critical. This paper tackles flight dynamics and control for aerial vehicles subjected to the stall phenomenon. We propose a class of modeling functions for the lift coefficient, and we investigate the control problem. The equilibria analysis is addressed prior to the control design. We show that the stall phenomenon never forbids the existence of an equilibrium orientation for any reference trajectory, but the uniqueness of this orientation is not in general ensured. Consequently, the equilibrium orientation can be subjected to discontinuities leading to an ill-conditioned control problem. Feedback control laws are derived for reference velocities associated with continuous equilibrium orientations.