Papers by Keyword: Flapping

Abstract: Dragonflies possess one of the most maneuverable flights among various insects. As the bionic Micro Air vehicles (MAVs) with the flight capabilities like dragonflies have been widely applied, detailed studies of dragonfly flight become critical and necessary for improvement and accomplishment of MAVs design. The phase relation between the forewings and hindwings is the most distinct feature of dragonfly flight and it plays an important role in the aerodynamic performance. In this paper, both tethered and quasi-free flapping flight of the dragonfly Pantala flavescens was filmed using a high-speed camera in indoor laboratory. Dragonflies tend to flap in-phase when an additional force is expected, while out-of-phase flapping is conducive to the stability and control of flight. In the takeoff maneuver, the large-and small-amplitude wingbeat alternated. Dragonflies obtain a high acceleration rapidly by the suddenly enlarged wingbeat amplitude which increases by 42%, and maintain the velocity and make ready for following acceleration by the small-amplitude but high-frequency wingbeat with amplitude decreases by 51% and frequency increases by 30% relatively.

Abstract: Myliobatidae is a family of large pelagic rays including cownose, eagle and manta rays. They are extremely efficient swimmers, can cruise at high speeds and can perform turn-on-a-dime maneuvering, making these fishes excellent inspiration for an autonomous underwater vehicle. Myliobatoids have been studied extensively from a biological perspective; however the fluid mechanisms that produce thrust for their large-amplitude oscillatory-style pectoral fin flapping are unknown. An experimental robotic flapping wing has been developed that closely matches the camber and planform shapes of myliobatoids. The wing can produce significant spanwise curvature, phase delays down the span, and oscillating frequencies of up to 1 Hz, capturing the dominant kinematic modes of flapping for myliobatoids. This paper uses dye flow visualization to qualitatively characterize the fluid mechanisms at work during steady-state oscillation. It is shown that oscillatory swimming uses fundamentally different fluid mechanisms than undulatory swimming by the generation of leading-edge vortices. Lessons are distilled from studying the fluid dynamics of myliobatoids that can be applied to the design of biomimetic underwater vehicles using morphing wing technology.