Modeling of High Aspect Ratio Active Flexible Wings for Roll Control

Abstract

The study of wing-warping roll control for high-altitude long-endurance vehicle wings is the primary objective of this paper. For that, a formulation is developed for the preliminary design of high aspect ratio active flexible wings. The formulation captures the nonlinear (large) deflection behavior of the wings, the effects of anisotropic piezoelectric composites embedded in the skin, and the unsteady subsonic aerodynamic forces acting on the wing. Because the wing is long and slender, it can be modeled as a beam undergoing three dimensional displacements and rotations. The cross sectional stiffness, inertia, and actuation properties of the wing are calculated along the span, and then incorporated into the 1-D nonlinear beam model derived in this paper. Finite-state unsteady subsonic airloads are incorporated to complete the state space aeroelastic model. The result is a low order model, capable of representing the important aeroelastic behavior, suitable for preliminary structural design and control synthesis. The capabilities of the formulation are exemplified at the end. Among other things it is shown that the wing-warping control with embedded anisotropic piezocomposite actuators can be more effective than conventional aileron for roll control.