A review of beetle hindwings: Structure, mechanical properties, mechanism and bioinspiration

Insects have a small mass and size and a low flying Reynolds number. Consequently, they serve as an excellent bionic representation of a micro air vehicle (MAV). Coleoptera (popularly referred to as beetles) have different characteristics from other flying insects. Not only can they fly at a low Reynolds number, but they also have deployable hindwings, which directly leads to a reduction in the size of their bodies. In narrow working spaces or unfavorable environments, a beetle's hindwings can fold automatically under the hard elytron. When the environment becomes conducive to flight, the hindwings can extend and help the beetle take off. This characteristic provides inspiration for the design of a bionic deployable wing system. In this paper, the structures and mechanical properties of hindwings and the mechanism of hindwing movement are reviewed, in addition to research on bioinspired deployable wings.