Integral aerodynamic-structural-control wing design

Abstract

The aerodynamic-structural-control design of a simplified wing and a forward-swept composite wing are studied. In the first example, the wing is modeled as a beam with a control surface near the wing tip. The torsional stiffness is the only physical property varying along the span. The aerodynamic model is based on strip theory, and the control model is based on output feed-back control. With the structural-control interaction being the main focus, two different approaches are taken for the simplified wing design: (1) a sequential approach, (2) an integrated approach. In each approach the wing is designed for minimum weight subject to divergence and control deflection constraints. The results of this study indicated that while the integrated approach produced a better design than the sequential approach, the difference was minimal.

In the second example, a forward-swept composite wing is designed for a high subsonic transport aircraft. The structural analysis is based on finite-element method. The aerodynamic calculations are based on vortex-lattice method, and the control calculations are based on output feed-back control. The wing is designed for minimum weight subject to structural, aerodynamic/performance and control constraints. Efficient methods are used to calculate the control deflection and efficiency sensitivities which appear as second order derivatives in the control constraint equations. To suppress the aeroelastic divergence of the forward-swept wing, and to reduce the gross weight of the design aircraft, two separate cases are studied: (1) combined application of aeroelastic tailoring and active controls, (2) aeroelastic tailoring alone. The results of this study indicated that, for this particular example, aeroelastic tailoring is sufficient for suppressing the aeroelastic divergence, and the use of active controls was not necessary.