Aerodynamic power efficiency comparison of various micro-Air-vehicle layouts in hovering flight

Flapping rotary wing, rotating wing, and flapping wing are feasible wing layouts applicable to micro-Air-vehicles capable of hovering flight.Anumerical study in this paper presents which wing layout can be more efficient in terms of aerodynamic power for the given kinematic and geometric parameters with or without the constraint of vertical force. In the cases under typical conditions, rotating wing layout is the most efficient one when a small vertical force is needed. However, if a much larger vertical force is required, flapping rotary wing is the only wing layout that fulfills the requirements of the two aspects due to its coupling effect. At relatively high Reynolds number (Re > 2000), flapping amplitude (>70°), and aspect ratio (= 6), comparative relationships from the cases under typical conditions among three wing layouts in terms of vertical force and aerodynamic power efficiency are kept unchanged. Nevertheless, at relatively low Re(< 500), flapping amplitude (<40°), or aspect ratio (=3), horizontally flapping wing and flapping rotary wing could achieve higher aerodynamic power efficiency with a larger vertical force. These findings have great significance in guiding us to select an appropriate wing layout based on various design conditions and requirements in primary design phase to ensure efficiency in micro-Air-vehicle design.