Design Guidelines for Flapping-Wing Micro UAVs

The effect of various wing parameters on the performance of a micro air vehicle using insect-like flapping wings is studied. A nonlinear aerodynamic model that was developed for modelling the flow associated with such wings in the hover is used to make a parametric study. The effects of both wing kinematics and wing shape on a flapping wing is investigated by considering their influence on lift and lift-to-torque ratio. A default set of parameters is defined and wing performance is measured with respect to this benchmark case. It is found that lift is greater for larger stroke amplitudes and higher flapping frequencies, varying almost as the square in both cases. The effect of advanced wing rotation is generally to improve the lift performance but lift-to-torque ratio begins to diminish beyond a lead of about 5% of the flapping cycle. A number of wing shape parameters are also investigated and it is found that the effect of increasing aspect ratio is to improve lift performance but at the detriment of lift-to-torque ratio. Although increasing wing area also increases lift for the flapping wing, it further shows a general improvement in lift-to-torque ratio. Finally, a comparison of some synthetic wing planform shapes reveals that wing designs with substantial area outboard are more favourable due to their ability to extract larger forces from the higher outboard velocities. However, such wings come with the cost of higher wing-root bending moment.