Force Measurements on a Flapping and Pitching Wing at Low Reynolds Numbers

Force measurements from experiments conducted in water on a flapping-and-pitching thin flat plate wing of semi-elliptic planform at low Reynolds numbers are reported. Time varying force data, measured using a force transducer, provide a means to understand the mechanisms that lead to enhanced performance observed in insect flight compared to fixed wing aerodynamics. Experimental uncertainties associated with low level (~1N) fluid dynamic force measurements on flapping-and-pitching wings are addressed. A previously proposed pitching mode in which the leading edge and trailing edge switch roles to allow using cambered airfoils has been shown to be viable, and may have advantages over the non-switching mode. The present data are part of a larger database planned to experimentally investigate various aspects of insect flight including another previously proposed idea that performance may be improved by flying at optimum reduced flapping frequency. The study has applications in micro air vehicle development.