Drag Reduction Methodology for Adaptive Tailless Aircraft

An approach is presented for determining optimum lift distributions for adaptive tailless aircraft. In this study, wing adaptation is achieved using multiple trailing-edge flaps that are used to optimally distribute the lift of the wing such that drag is minimized. For tailless aircraft that are stable in pitch, the lack of a secondary lifting surface makes it necessary that the lift distribution on the wing also satisfies a pitching-moment constraint to ensure trim. The current work implements a numerical approach that solves for the optimal scheduling of multiple trailing-edge flaps on the wing of a tailless aircraft for various flight conditions with a pitching-moment constraint to reduce both induced and profile drag. The approach uses superposition to construct the spanwise lift distribution from basic and additional loadings, and decomposes the flap-angle distribution into mean and variation distributions. Together, these elements enable the solution of the problem using semi-analytical methods that also provide insight. The results are presented for a planar, swept, tapered wing with two airfoil-section choices to verify the theory and provide insight for trade studies.