Design Optimization of a Variable-Span Morphing Wing for a Small UAV

Abstract

The present work describes the design optimization of a variable-span morphing wing to be fitted to a small UAV which flies in the speed range 11m/s to 40m/s. An in-house aerodynamic shape optimization code, which uses a viscous two-dimensional panel method formulation coupled with a non-linear lifting-line algorithm or a non-linear vortex lattice algorithm and a sequential quadratic programming optimization routine, is used to solve a drag minimization problem to determine the optimal values of wing span for various speeds of the vehicle’s flight envelope while subject to geometric constraints. A simple weight representation model based on semi-empirical formulae and data obtained from a wing prototype was used to estimate the variable-span wing weight. Near its maximum speed it is possible to obtain a 20% wing drag reduction with the variable-span wing in comparison with the original fixed wing. An analysis is also developed and performed to compute the roll rate available with asymmetric span control of the variable-span wing showing that this matches the roll authority of a conventional wing with aileron control.