Aerodynamic and flying characteristics of modern volleyball

Abstract

In this research, four types of volleyballs used in modern day competitions were targeted to clarify the aerodynamic and trajectory characteristics through wind tunnel experiments and a hitting robot. We confirmed, in particular, that the critical Reynolds number (Recr) changed depending on the ball type and panel orientation (i.e., side A and side B). Recr for a conventional panel-type volleyball Mizuno volley ball was determined to be ~2.8 × 10⁵ (Drag coefficient; C_d = 0.16) on panel side A and 2.0 × 10⁵ (C_d = 0.20) on panel side B. On the other hand, Recr for the Olympic Official Mikasa ball was 2.9 × 10⁵ (C_d = 0.16) in the panel orientation A and 3.3 × 10⁵ (C_d = 0.15) in panel orientation B. Moreover, we found that the landing position of all volleyballs varied depending on the ball type and the orientation of the panel. In particular, the Molten ball has a longer flight distance than other balls and its landing point was biased toward the left side. On the other hand, the Mikasa ball had a relatively short flight trajectory and its landing point was biased to the right. Therefore, it can be hypothesized that during a float serve, the flight trajectory will change depending on the panel orientation and type of volleyball.