Aerodynamic analysis of upper surface wing morphing efficiency for the S4 Éhecatl unmanned aerial system

This paper investigates the aerodynamic performance improvement of the Hydra Technologies S4 Unmanned Aerial System using a morphing wing concept. A part of the wing's upper surface is morphed, as function of the flight condition, in order to increase the S4's lift-to-drag ratio. The wing airfoil shape optimizations are performed using a hybrid Artificial Bee Colony and Broyden-Fletcher-Goldfarb-Shanno algorithm, coupled to a two-dimensional viscous flow solver. The wing geometries are reconstructed based on the morphed airfoils, and three-dimensional computations are performed, including the effects of the fuselage and tail, using a panel method. The viscous drag is estimated using strip theory, empirical and experimental approximations. The optimizations and three-dimensional results are obtained for fifteen flight conditions, corresponding to cruise and surveillance flights at various altitudes. Comparisons are made between the original and morphed geometries, and identify the conditions for which significant lift-to-drag ratio improvements are obtained using the upper surface morphing concept.