Insect-inspired two-vein flapping wings with anisotropic rigidity

A network of veins confers insect wings their anisotropic rigidity. We study the aerodynamics of a flapping flexible wing with a two-vein pattern that mimics the elastic response of insect wings in a simplified manner. The experiments reveal an optimal configuration for aerodynamic force production by the flapping wings when the two veins are spaced at an angle of about 20 degrees. The 3D deformation of the wings is monitored during the experiment while, simultaneously, the instantaneous aerodynamic forces are recorded with a force balance. The optimal distribution of the vein network in terms of propulsive force is well explained by a model based on the average wing deformation during a flapping cycle.