An optimization study on load alleviation techniques in gliders using morphing camber

This study explores wing morphing for load alleviation as a means to reduce the required wing structural weight without compromising aircraft performance. A comparative study between the lift-to-drag ratio (L/D) performance of a fixed wing glider (FWG) and a cambered morphing wing glider (CMWG) is presented. Both aircraft are aero-structurally optimized for the best L/D for a given speed and payload mass. A combination of lifting-line theory and 2D viscous calculations is used for the aerodynamics and an equivalent beam model is employed for the structural analysis. Pull-up and -down maneuvers at 25 m/s and near stall angle of attack are assumed as critical load cases. Results of the FWG optimization are shown for several trimmed flight conditions with varying mass and velocity. Results are compared to the ones from the CMWG optimization and conclusions are drawn on the improvement in the L/D ratio throughout the flight envelope and on potential reductions in the wing structural mass due to the load alleviation strategy. The wing camber adaptation provides significant performance gains in a large range of flight speeds with negligible penalties in the low speeds range. However, maneuverability is penalized.