Abstract: Aiming at the multi-parameter coupling problems of flapping-wing flight of birds, a 3D model of bird-like flapping-wing air vehicle (FAV) is established based on overall dimensions of bird. A multi-degree-of-freedom motion model of “swing-torsion-bending and folding” is built. The XFlow is used to analyze the effects of flight angle and flapping-wing bending-folding. Research results show that peak values of lift coefficient and drag coefficient change with different flight angles; at the zero flight angle, minimum mean drag coefficient and maximum lift-drag ratio will be achieved and avail to level flight. Caused by the bending-folding effect, violent vortex and negative pressure are produced on the upper surface of outer wings, which will improve lift-drag ratio and impact drag coefficient less.

Key words: bird-like flapping-wing air vehicle, flight angle, bending-folding, XFlow, aerodynamic characteristics analysis