Aerodynamic Characteristics of a Tumbling Plate under Free Flight

Abstract

In this study, we deal with the tumbling, which is a rotating motion with the axis perpendicular to the falling direction. Our purpose is to reveal the fundamental aerodynamic characteristics of the tumbling, experimentally. Regarding a test plate, we consider a prism with a rectangular cross section with a depth-to-width ratio λ of 0.3. The results are as follows. The reduced terminal rotating rate Ω * , the lift coefficient C L , the drag coefficient C D and the lift-to-drag ratio C L /C D are independent of the aspect ratio AR, when AR is greater than 10. As the inertia moment ratio I * increases from zero to 50, Ω * , C L and C D increase. However, Ω * , C L and C D become almost constant, at I * greater than 50. We propose the empirical formulae to predict them. At low I * , the tumbling shows a dominant periodicity of 360 deg.