Aerodynamic Performance of a Flyable Flapping Wing Rotor With Passive Pitching Angle Variation

This article is based on an experimental study on the aerodynamic performance of a flapping wing rotor (FWR) and enhancement by passive pitching angle variation (PPAV) associated with powered flapping motion. The PPAV (in this article, 10(o)-50(o)) is realized by a specially designed sleeve-pin unit as part of a U-shape flapping mechanism. Through experiment and analysis, it is found that the average lift produced by an FWR of PPAV is >100% higher than the baseline model, the same FWR of a constant pitching angle 30(o) under the same input power. It is also noted that the lift-voltage relationship for the FWR of PPAV is almost linear and the aerodynamic efficiency is also over 100% higher than the baseline FWR when the input voltage is under 6 V. The aerodynamic lift or efficiency of the FWR of PPAV can be also increased significantly by reducing the weight of the wings. An FWR model is fabricated and achieved vertical take-off and free flight powered by 9 V input voltage. The mechanism of PPAV function provides a feasible solution for aerodynamic improvement of a bioinspired FWR and potential application to micro air vehicles.