Aerodynamic characteristics of new soccer balls
University of Tsukuba, Japan 1. INTRODUCTION Many studies have been conducted on the aerodynamics of sports balls, for example, golf balls (Bearman and Harvey, 1976; Smits and Ogg, 2004), cricket balls (Mehta et al., 1983), tennis balls (Haake et al., 2000; Mehta and Pallis, 2001), baseballs (Watts and Ferrer, 1987), rugby balls (Seo et al., 2004), volleyballs (Wei et al., 1988; Cairns, 2004), and soccer balls (Asai et al., 2007). Mehta (1985) conducted the first proper review of sports ball aerodynamics by investigating the performance of cricket balls, golf balls, and baseballs in detail and demonstrated that the drag on a ball is largely determined by the size and deflection of its wake. However, few such studies have been conducted on new soccer balls. Specifications for soccer balls are determined by Fédération Internationale de Football Association (FIFA), and new soccer balls that meet these specifications are routinely manufactured and used in competitive and recreational sports around the world. However, the aerodynamic characteristics of such newly manufactured soccer balls have not been clarified.