Numerical optimization of the S4 Éhecatl UAS airfoil using a morphing wing approach

Abstract

In this paper, we describe the new methodology and the results obtained for multiple flight conditions optimization of the airfoil of the S4 unmanned aerial system, using a morphing wing approach. The goal of reducing the airfoil drag coefficient over a broad range of speeds and angles of attack has been achieved using an in-house optimization tool based on the relatively new Artificial Bee Colony algorithm, coupled with the Broyden-Fletcher-Goldfarb-Shanno algorithm to provide a final refinement of the solution. The obtained results were validated with an advanced, multi-objective, commercially available optimizing tool. The aerodynamic calculations were performed using a 2D linear panel method, coupled with an incompressible boundary layer model and a transition estimation criterion, to provide accurate estimations of the airfoil drag coefficient. For very small displacements of the airfoil surface, less than 2.5 mm, drag reductions of up to 14% have been achieved for a wide range of different flight conditions.