Force generation and wing deformation characteristics of the ’DelFly II’ MAV in hovering flight conditions

The study investigates the relation between wing deformation and unsteady force generation of the flapping-wing MAV DelFly II in hovering flight configuration. The three-dimensional wing deformation was measured with a stereo-vision system, while fluid forces were acquired simultaneously with a force sensor. Comparison of the results for different flapping frequencies reveals different wing kinematics and deformation characteristics. The high flapping frequency case produces higher forces throughout the complete flapping cycle. Moreover, a phase difference occurs in the variation of the forces, such that the low flapping frequency case precedes the high frequency case. A similar phase lag is observed in the temporal evolution of the wing deformation characteristics, suggesting that there is a direct link between the two phenomena.