Tuning the Deformation of Flapping Wing to Improve the Flight Efficiency of Dove FWMAV

How to conveniently tune the flexibility of the composite anisotropic flapping wing to an optimum level to improve flight efficiency is still an open question. Two simple methods have been put forward to realize the quick adjustment of flexibility to improve flight efficiency: one is to change the diameters of two outer ribs of the baseline flapping wing, and the other is to add a minor mass lump at the end of two outer ribs of the baseline flapping wing. The ground experimental results show that adding a minor mass lump at the end of the outer ribs can simultaneously improve the static thrust and the static propulsive efficiency, whereas increasing diameter can only improve the static thrust. A flight test was performed to verify that adding a proper mass lump can effectively improve the flight efficiency by 9% compared with that of the baseline flapping wing. Adding a mass lump can simultaneously improve the static thrust and propulsive efficiency. However, the trade-off between the loss of lift and the increase of thrust that arises from the nonlinear wing deformation and the increase of power consumption contributed by the added mass should be carefully weighed. Furthermore, a new parameter can be used to determine whether the flight performance can be effectively improved simply by tuning the mass distribution.