We remind the reader that Re = 2 × 105 corresponds to a speed of about 14m s−1 (or
about 31.5 miles per hour). Large spin parameters correspond to low-speed, high-spin kicks in
the game of soccer. A typical David Beckham free kick with lots of sidespin has Re 5×105
and Sp = 0.2 [1]. The University of Sheffield sports hall’s size limits our ability to study
balls launched at Reynolds numbers greater than about 3 × 105. Balls launched at greater
speeds collide with the sports hall’s rafters or far wall. Studying larger Reynolds-number
launches would require us to set up a net or other stopping device just past the region filmed by
camera 1. We may pursue such an experiment in the future.