Aerodynamic Characteristics of a Rugby Ball Spinning on Its Transverse Axis

Abstract

We have measured aerodynamic forces and moments acting on a rugby ball spinning on its transverse axis by wind tunnel experiments. A full-size model of a rugby ball was tested in a low-speed wind tunnel with a 1.5m×1.0m rectangular nozzle. It was made of fiber reinforced plastics by molding a fully-inflated ball. The spinning mechanism was composed of a motor and four shafts inserted the ball along its transverse axis. The results are summarized as follows : the lift increases with increasing the spin rate because of the Magnus force. The Magnus force is at its maximum when the spinning (transverse) axis is perpendicular to the flight direction. The side force depends on the angle between the spinning axis and the direction of flight. The side force is a maximum when this angle is 45°.