Revisiting the Fundamentals of Control Surface Reversal Including Nonlinear Effects

Control surface reversal is a classical aeroelastic phenomenon commonly investigated during aircraft development. It occurs under static equilibrium between the elastic restoring torque and the aerodynamic moment on the system. Besides the equilibrium, it depends on an additional condition defined through the lift force. As discussed in the literature, this second condition can be considered by two different approaches for a linear model. In this context, this paper discusses the reversal considering typical nonlinearities. The two different approaches are compared. The findings demonstrate that the influence of nonlinearities is correctly considered when reversal is defined as when the lift due to control surface rotation is zero. Also, it is concluded that nonlinear reversal cannot be determined by employing the generalized reversal condition often discussed in the classical linear problem. (AU)