Cicada wings experience drag in the downstroke, and generate thrust during the upstroke. In the cicada forward flight, approximately 79% of the total lift is generated during the downstroke. Some other vortex features include: independently developed left- and right-hand side leading edge vortex (LEV), dual-core LEV structure at the mid-wing region and near-wake two-vortex-ring structure. Another is the cicada posterior body vortex, which entangles with the vortex ring composed of wing tip, trailing edge and wing root vortices. One is the thorax-generated vortex, which helps the downwash flow, indicating a new phenomenon of lift enhancement. We report two new vortices generated by the cicada's wide body. Free forward flight of cicadas is investigated through high-speed photogrammetry, three-dimensional surface reconstruction and computational fluid dynamics simulations.
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