Some aeromechanical aspects of insect-like flapping wings in hover

Abstract

Micro air vehicles (MAVs) are defined as flying vehicles ca. 150 mm in size (hand-held) weighing 50–100 g, and are developed to reconnoitre in confined spaces (inside buildings, tunnels, etc.). For this application insect-like flapping wings are an attractive solution and hence the need to realize the functionality of insect flight by engineering means. Insects fly by oscillating (plunging) and rotating (pitching) their wings through large angles, while sweeping them forwards and backwards. During this motion the wing tip approximately traces a figure-of-eight and the wing changes the angle of attack (pitching) significantly. This paper presents some aspects of aerodynamic modelling and mechanical design pertinent to engineering realization of insect-like flapping wings on the MAV scale. The aerodynamic modelling uses an indicial Polhamus approach which is implemented in a modular manner. Comparisons are presented with experimental force data from a dynamically scaled insect model and generally show good agreement. The design is then described of a four-bar linkage mechanism to drive an insect-like flapping-wing motion. The indicial Polhamus aerodynamic model was used as part of the design process to predict wing loading. This highlighted some interesting interactions between the position of the wing pitch axis and its loading. The paper concludes with some directions for future work in this challenging field.