Modeling and simulation of cormorant's webbed-feet assisted take-off from water surface

Cormorants can take off from water surface by cooperatively regulating the propulsion respectively produced by wings and two webbed-feet, which can provide an inspiration for an aquatic unmanned aerial vehicle's (AquaUAV) takeoff from water. This paper adopts modeling and simulation methods to investigate the take-off process of a cormorant from water surface, and to explore how the wings and feet function to improve the takeoff performance on water. Quasi-steady blade element method and hydrodynamic equation were used to analyze the forces produced by flapping wings and slapping feet respectively. The dynamic model of the cormorant's take-off from water was established. Then video-based kinematic data were obtained to verify the accuracy of this model. Further, The effects of the flapping frequency, body angle attack and webbed feet area on takeoff distance were investigated and discussed based on simulation results. The results demonstrate that the flapping frequency and webbed feet area contributes substantially to reducing take-off distance.