Aerodynamic performance comparison between micro revolving wing and flapping wing

In comparison with flapping mode, a little more amount of average lift and better aerodynamic efficiency are obtained by a revolving wing in hovering. The ratio of lift to drag can approach 3.1 in Reynolds number 4000 when a wing revolving at 15° angle of attack, and high lift can be produced with several rotors at 15° angle of attack. Hence, several rotors at 15° angle of attack seem to be a more attractive candidate than flapping mode in the design of insect-scale aircraft.