Aerodynamics of oval shaped sports balls

Oval shaped sports balls are used in American, Australian and rugby football codes. The flight trajectory of oval shaped balls largely depends on their aerodynamic characteristics which are significantly different from spherical balls. Despite the popularity of the game, it appears that there is scant information on the aerodynamic forces experienced by oval shaped balls especially the American and Australian Rules football is available in the open literature. Attempts were made to construct the flight trajectory of oval shaped balls, however without knowing the aerodynamic properties; it is difficult to build such a model. The primary purpose of this study is to experimental measure the aerodynamic forces of several oval shaped balls (American football, rugby ball and Australian Rules football) under a range of wind speeds and yaw angles. The non-dimensional drag coefficient were estimated and compared. The results indicate that the drag coefficients of these balls are close to each other. The results also illustrate that the drag coefficient is nearly four times lower when the longitudinal axis is pointed to the wind.