02.4 - Applied Aerodynamics
STRATEGIES FOR ACHIEVING BACKWARD FLIGHT BY A DRAGONFLY
A.T. Bode-Oke¹, S. Zeyghami, Lehigh University, United States; H. Dong¹; ¹University of Virginia, United States
Highly maneuverable insects such as dragonflies have a vast array of flight capabilities including forward flight, hovering, sideways flight, upside down flight and even backward takeoff flight. In this disquisition, we studied the kinematics and aerodynamics of backward takeoff in dragonflies and compared them to those of forward takeoff. High speed videography and accurate 3D surface reconstruction techniques were employed to extract details of the wing and body motions. While the body velocities of both forward and backward flights were similar, the body orientation as well as the wing kinematics largely differed. Our results indicate that tilting the stroke plane angle of the wings and changing the orientation of the body relative to the flight path are the major means to achieve backward flight. In addition, our detailed analysis of the flow in these flights shows that interaction of the wakes from the fore and hind pair of wings enhances performance of backward flight.