Experimental optimization of wing shape for a hummingbird-like flapping wing micro air vehicle

Abstract

Flapping wing micro air vehicles (MAVs) take inspiration from natural fliers, such as insects and hummingbirds. Existing designs manage to mimic the wing motion of natural fliers to a certain extent; nevertheless, differences will always exist due to completely different building blocks of biological and man-made systems. The same holds true for the design of the wings themselves, as biological and engineering materials differ significantly. This paper presents results of experimental optimization of wing shape of a flexible wing for a hummingbird-sized flapping wing MAV. During the experiments we varied the wing 'slackness' (defined by a camber angle), the wing shape (determined by the aspect and taper ratios) and the surface area. Apart from the generated lift, we also evaluated the overall power efficiency of the flapping wing MAV achieved with the various wing design. The results indicate that especially the camber angle and aspect ratio have a critical impact on the force production and efficiency. The best performance was obtained with a wing of trapezoidal shape with a straight leading edge and an aspect ratio of 9.3, both parameters being very similar to a typical hummingbird wing. Finally, the wing performance was demonstrated by a lift-off of a 17.2 g flapping wing robot.

Wing inertia as a cause of aerodynamically uneconomical flight with high angles-of-attack in hovering insects

“…The PL, which represents the amount of vertical force per unit power, was used as a basic metric to assess the economical hovering flight in this study (Young et al, 2009;Mayo and Leishman, 2010;Zheng et al, 2013). Based on the 3D wing kinematics of the beetle, we sought the best local AoA at each wing section along the wingspan for the highest PL by using a simple approach developed in our previous work (Phan et al, 2017a), as depicted in Fig.…”

“…In addition, the method based on BET, which requires cheap and less time-consuming computations, allows us to obtain the results without a high cost. Most of the available optimization approaches for the flapping wings are performed experimentally (Chaudhuri et al, 2014;Nan et al, 2017) or based on simplified 2D wing kinematics (Usherwood, 2009;Taha et al, 2013;Pesavento and Wang, 2009;Berman and Wang, 2007). While we lack a fully formulated global optimization approach to find the optimal 3D wing kinematics, this simple optimization-like method may be an appropriate way to obtain the optimal AoA for a 3D wing using a real insect's wing kinematics.…”

“…During flapping motion, insects spend extra flight energy to overcome wing inertia. Consequently, wing inertia may reduce the hovering efficiency of the flapping wing, which is based on power loading as a performance metric (Young et al, 2009;Mayo and Leishman, 2010;Zheng et al, 2013).…”

Aerodynamics and dynamic stability of micro-air-vehicle with four flapping wings in hovering flight

“…With the theories how insects fly in mind, scientists turned their focus into how to fully apply those flying principles to a man-made FMAV and conducted systematical researches on aerodynamic, structure, power and control problems. For example, extensive experimental and numerical studies have been conducted on the effects of wing geometrical [14][15][16] (including wing aspect ratio, area, span et al) and on both lift and power consumption. Wing passive deformations beneficial for lift augment and power efficiency enhancement have also been discovered [17][18][19][20].…”

Can Scalable Design of Wings for Flapping Wing Micro Air Vehicle Be Inspired by Natural Flyers?

“…Natural flyers have wings with several degrees of freedom when flapping. They can vary from one flight mode to another by adjusting the wing motion pattern with the wing shape deformation [16,20]. It means that natural flyers flex their wings actively or passively to change the shape, geometry, and surface of the wing when flapping.…”