Experimental Study on Aerodynamic Performance of Flapping Wing with One-Way Holes/Gaps

Gaps between feathers can be observed when some birds are flying. They can control the opening and closing of gaps to achieve the goal of good aerodynamic performance. The effects of the wing gaps on aerodynamic performance is investigated by experimental study. Firstly, a kind of flapping wing with one-way holes is designed and tested. The holes are connected by hinge, which is open during the up-stroke process and close during the down-stroke process. One-way holes can increase the lift significantly. However, the hinge connection makes the movement process less continuous. And there’s more resistance because the windward area is increased by hinged holes. Further on, the method was improved by using one-way deforming characteristics of bird feathers. The goose feathers are used as a covering skin of flapping wing, which can have continuous opening and closing gaps, making the flapping process more smoothly and getting smooth aerodynamic characteristics. The results show that the one-way holes/gaps flapping wing can effectively increase the lift and reduce the power consumption. The using of natural feathers as flapping wing covering skin is a conducive way to improve the aerodynamic performance.