Aerodynamics and flight stability of a prototype flapping micro air vehicle

Inspired by novel mechanisms in insect and bird flights, in particular, the clap-and-fling mechanism associated with the aerodynamic force enhancement owing to the wing-wing interaction, we developed a prototype flapping micro air vehicle (fMAV), which is weighted 2.4 - 3.0 g, equipped with a X-type wing and a wingspan of 12 -15 cm. In this study, we carried out an integrated study of flexible wing aerodynamics and passive dynamic flight stability of the MAV by a combination of flexible wing kinematics and force measurements and computational approaches. We designed a high-speed camera filming system to measure the flexible wing kinematics and deformations and constructed the computational wing kinematic model. Together with the force measurements we investigated the wing stiffness effects on the force generation associated with the flexible wing deformation. We further used a biology-inspired, dynamic flight simulator to evaluate the aerodynamic performance of the flexible wing MAV. This simulator, by integrating the modeling of realistic wing-body morphology and realistic flapping-wing and body kinematics, provided an evaluation of the MAV's unsteady aerodynamics in terms of vortex and wake structures and their relationship with aerodynamic force generation. Our results show that the clap-and-fling mechanism is indeed realized by the prototype four-winged MAV and the flexible wing deformation even further enhance its effects. Furthermore, we employed a computational approach to analyze the passive dynamic flight stability of the MAV's forward flight. Results based on a linear theory indicated that the MAV is very likely of dynamical stability even with no active feedback control system.