The Autorotation Boundary in the Flight of Samaras

Abstract

The flight behaviour of the samaras can be analysed precisely by performing tests on free-falling rotary samaras in a vertical wind tunnel. They are freely suspended in vertically ejected air flow and lit up by a stroboscopic lamp. By performing similar tests with simulated models of samaras (which are made of styrene foam and sliced balsa in the form of a thin paper with simplified geometrical configuration), the autorotation boundary of the center of gravity can be determined in connection with the geometrical configuration of the models. The flight characteristics such as descending speed and spinning rate of autorotation depend strongly on the combination of the location of center of gravity, the disc loading or wing loading, the curve of mean chord line or camber and the surface roughness near the leading edge of the model.