Optimum distributed wing shaping and control loads for highly flexible aircraft

In highly flexible aircraft, the large structural slenderness associated to their high-aspect-ratio wings, while bringing challenges to the design, analysis, and control of such aircraft, can be pro-actively exploited for improving their flight performance, resulting in mission-adaptive morphing configurations. This paper studies the optimum wing bending and torsion deformation of highly flexible aircraft, with distributed control loads along the wing span to achieve the optimum wing geometry. With the goal of improving flight performance across the entire flight regime, a modal based wing shaping optimization is carried out, subject to the requirement of trim and control cost limitation. While a single objective of the minimum drag can be used to find the optimum wing geometry, this paper further considers a trade-off between flight efficiency and structural integrity. In this trade-off study, a multi-objective optimization is formulated and performed, targeting for both minimizing the drag to improve flight efficiency and reducing the gust-induced wing bending moment to enhance the structural integrity. Finally, this paper explores the minimum control cost for different targets of combined flight efficiency and structural integrity. This paper provides not only an efficient way to search for the desired wing planform geometry at a given flight condition but also insights of the required control effort that is necessary to maintain the wing geometry.