Experimental investigation of the flapping performance on `DelFly Micro’

This study addresses the quantification of the aerodynamic performance of the ‘Delfly Micro’, which is currently the smallest ornithopter in the ‘Delfly’ family with an X-Wing configuration. Aerodynamic forces were measured on a full-scale ‘Delfly Micro’ by a sophisticated balance system. In view of the influence of the wing flexibility on the performance, wings with varying membrane thicknesses and stiffener orientations were examined in hovering case. To characterize the forward flight regime, aerodynamic forces were also measured with varying free stream velocities and angles of attack in wind tunnel. The results indicate that wing flexibility indeed influences the aerodynamic performance, where a more rigid wing can produce more force, whereas with a lower force to power ratio. According to the wind tunnel data, the ‘Delfly Micro’ can attain a flight speed up to 3 m/s, at a flapping frequency over 30 Hz and angle of attact of 30 degrees