This experiment used a low-speed circulating wind
tunnel with a six-component balance (maximum wind
velocity = 40 m s–1; measuring section = 1.5 × 1 m; turbulence
level = 1%) at the Department of Aeronautics
& Astronautics, Tokai University, Japan. Tests were
performed on a hand-stitched soccer ball with panels
(Size 5 Adidas Fevernova), and two thermally bonded
soccer balls with panels (Size 5 Adidas Roteiro and
Size 5 Adidas Teamgeist), all of which were officially
approved for use in international games. Each ball was
supported at the rear, with the sting fitted to the sixcomponent
wind tunnel balance (Fig. 1). Each ball was
fixed to the sting with an adhesive, so that it could not
rotate.