Multidisciplinary Drag Optimization of Reduced Stiffness Flexible Wing Aircraft With Variable Camber Continuous Trailing Edge Flap

This paper presents a study of the optimization of an aeroelastic wing shape in order to improve aerodynamic efficiency through minimization of drag at different cruise flight conditions. The aircraft model used for the study is based on the NASA Generic Transport Model (GTM), with the wing structures of the model incorporating a novel aerodynamic control surface known as the Variable Camber Continuous Trailing Edge Flap (VCCTEF). The wings of the aircraft are modeled both with a baseline stiffness distribution typical of current commercial aircraft, and also with the stiffness in both bending and torsion reduced by 50%. The aeroelastic structural framework developed for the GTM model is implemented using finite element analysis. Aerodynamic modeling conducted using a vortex-lattice method is coupled with the structural framework through a geometry generation tool to form the static aeroelastic model. Additional corrections are applied to the model to include aerodynamic effects due skin friction drag and potential shock formation at transonic flight conditions. Gradient-based constrained optimization, with the gradient approximated using a forward finite difference method, is conducted to tailor the initial wing jig-shape twist and VCCTEF deflection settings for drag reduction at offdesign cruise flight conditions. Optimization is performed on both the aircraft with baseline stiffness wings and the aircraft with half stiffness wings, and a comparison is made as to the effectiveness on wing shaping using the VCCTEF for a stiff versus more flexible wing. The results demonstrate the potential of utilizing the novel control surface on aircraft for wing shaping control to improve aerodynamic efficiency for both baseline stiffness and half stiffness wings.