Meeting Abstract
The smallest flying insects such as thrips and fairyflies have body lengths under 1 mm and operate at very low Reynolds number (Re) on the order of 10 or lower. Flapping flight is challenged in these size scales on account of large viscous forces on the wings. These insects often show unique biomechanical adaptations that include: wings with long bristles at the fringes, and the use of clap and fling wing-wing interaction to maximize wing amplitude. Ellington (1975) observed that the wings of the chalcid wasp Encarsia remain clapped (following end of the upstroke) for 20-25% of the wingbeat cycle. It is not clear if there is an inherent aerodynamic advantage associated with this pause time before the onset of downstroke via fling. In this study, we examined aerodynamic effects of varying pause duration using physical models of bristled wings inspired by biological data. A robotic model mimicking clap and fling motion was used to experimentally test different pause times. Non-dimensional lift and drag coefficients were calculated from strain gauge measurements. Peak lift coefficients in fling increased with increasing pause duration, whereas drag coefficients were nearly unchanged. We will present the effects of varying pause duration on chordwise flow structures.
