Fig. 13. Schematic reconstruction of vortex generation and shedding during the clap-and-fling maneuver using a generic Drosophila stroke kinematics. (A) Chordwise wing segments at the end of the upstroke, (B) during the clap phase of the two wings, (C) during the early fling phase and (D) the late fling right before the two wings separate for the downstroke. Leading and trailing edge vortices that are generated during the upstroke are shed into the wake at the end of each half stroke. The vortex system generates an inter-vortex stream towards the wing that is thought to enhance flight forces via momentum transfer. Due to near-clap conditions the low pressure region evolving between the wings during the fling pulls fluid around the leading and the trailing wing edges into the opening cleft.