Improving flight performance of the flapping wing MAV DelFly II

Recent years have seen an increasing interest in micro aerial vehicles (MAVs) and flapping flight in connection to that. The Delft University of Technology has developed a flapping wing MAV, “DelFly II”, which relies on a flapping bi-plane wing configuration for thrust and lift. The ultimate aim of the present research is to improve the flight performance of the DelFly II from both an aerodynamic and constructional perspective. This is pursued by a parametric wing geometry study in combination with a detailed aerodynamic and aeroelastic investigation. In the geometry study an improved wing geometry was found, where stiffeners are placed more outboard for a more rigid in-flight wing shape. The improved wing shows a 10% increase in the thrust-to-power ratio. Investigations into the swirling strength around the DelFly wing in hovering flight show a leading edge vortex (LEV) during the inand out-stroke. The LEV appears to be less stable than in insect flight, since some shedding of LEV is present. Nomenclature Symbol Description Unit f Wing flapping frequency Hz P Power W R DelFly wing length (semi-span) mm T Thrust N λci Positive imaginary part of eigenvalue τ Dimensionless time Abbreviations LEV Leading Edge Vortex MAV Micro Aerial Vehicle UAV Unmanned Aerial Vehicle