抄録
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 CL, the drag coefficient CD and the lift-to-drag ratio CL/CD 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*, CL and CD increase. However, Ω*, CL and CD 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.
