Need of different flapping styles for different flight phases of a flapping wing vehicle: A preliminary analysis

Abstract

Flapping wing vehicles ranging from a large bird sized model to a tiny insect-sized model were made successfully. Still, there is a lot of scope for further research, since their natural counterparts outperform them in most of the flight aspects. The fact that the natural flyers change their flapping style for different flight phases is taken for investigation. Aerodynamic forces at a wing section are analyzed using the general blade-element approach. Using vector mechanics, contributions of the sectional lift and drag forces to the thrust, lift and side force of the vehicle are derived and non-dimensionalized. All the three were in terms of four non-dimensional parameters - the sectional lift to drag ratio, advance ratio, stroke plane orientation and instantaneous flapping angle. The variations of the three force components with the four non-dimensional parameters were plotted. Flapping style with minimized side force and maximized the thrust and lift production is considered as that of efficient flying. The results demand that the stroke plane orientation, speed and amplitude of flapping should be varied for different phases of flight for efficient flying.