Resumen
The pattern of a modern volleyball is greatly different from that of a conventional volleyball, with several changes being made to the shape and design of the surface on the ball. Furthermore, at the 2020 Tokyo Olympics, a new volleyball (V200W; Mikasa) with 18 panels will be shown as the official ball. Therefore, this study compared the basic aerodynamic characteristics of conventional volleyballs with those of new designs in a wind tunnel. We used three full-size FIVB (Fédération Internationale de Volley-Ball) official volleyballs (V5M5000; Molten, MVA200; Mikasa and V200W; Mikasa) to determine the aerodynamic forces acting on each ball. The results indicate that the critical Reynolds number (Recr) differed depending on the ball types and their orientations. The Recr for the Molten ball (conventional) was determined to be ~3.4 × 105 (Cd = 0.17) on panel orientation A and ~2.7 × 105 (Cd = 0.14) on panel orientation B. Moreover, the Recr for the conventional Mikasa ball was determined to be ~2.6 × 105 (Cd = 0.14) on panel orientation A and ~3.0 × 105 (Cd = 0.13) on panel orientation B. On the other hand, the critical Reynolds number for the new volleyball (V200W) was ~2.9 × 105 (Cd = 0.17) in the panel orientation A and ~2.6 × 105 (Cd = 0.15) in panel orientation B. From these results, it can be hypothesized that, during a float serve, the flight trajectory will change depending on the type of volleyball and their orientation.