A new approach based on undulate propulsion theory for flapping wing analysis and design

This paper is aiming for improving new ways of aerodynamic analysis and high efficiency flapping motion design methods of flapping wing aircrafts, or ornithopter. The concept of Undulate Propulsion wave is put forward to better describe propulsive mechanism and it is found to be determinant of flapping wing aerodynamic efficiency. Based on relative conclusion and rigidity theory, a top-down design method for high efficiency flapping wing is extracted. Relationship between passive torsion or active torsion of flapping wing is also analyzed in this paper, and passive torsion is found an easier and more energy-saving way to match the efficiency optimal working point than active torsion. At last, a passive torsion flapping wing ornithopter is introduced, which is designed based on efficiency optimal method presented in this paper. The successful flight test demonstrated that the design method is effective and passive torsion can indeed match the efficiency optimal working point.