Measurement of Spanwise Torsional Angles and Camber Deformation on Wings of Free-flying Dragonflies

摘要

Knowledge of wing orientation and deformation during flapping flight is necessary for a complete aerodynamic analysis, but to date these kinematic features have not been simultaneously quantified for free-flying insects. A projected comb-fringe (PCF) method has been developed for measuring spanwise camber changes and torsional angles on free-flying dragonflies through the course of a wingbeat, which bases on projecting a fringe pattern over the whole measurement area and then measuring the wing deformation from the distorted fringe pattern. Experimental results demonstrate substantial camber changes both along the wingspan and through the course of a wingbeat. The ratio of camber deformation to chord length for hindwing was up to 0.11 at 75% spanwise with a flapping angle of -0.66 degree.