A sophisticated new model for assessing whether ball stop mitigation is required for a sports facility has been announced winner of the SAPCA Award 2021 for innovation.
Developed by SAPCA member Labosport, the Ball Trajectory Analysis service will help those responsible for designing, developing and operating sports facilities to accurately predict the types of ball stop methods needed. In many sports there is a real or a perceived risk of a ball leaving the field of play and ball stop mitigation is often required to protect users of a facility. The new service assesses not just whether mitigation is required, but also its recommended height and location.
The science of aerodynamic modelling
Labosport has developed highly-advanced trajectory models for a number of sports – including cricket, football, rugby and golf. The task for rugby was particularly challenging, owing to the shape of the ball.
“A sophisticated trajectory model was developed to analyse the trajectory of the rugby ball,” says Professor David James, MD of Labosport.
“The model was built using numerical programming software and incorporates aerodynamic drag and lift forces, and the significant complexities arising from the rugby ball’s rotation and its ovoid shape. Under rotation, the rugby ball’s cross-sectional frontal area constantly changes in relation to the air flow.
“The angle of attack between the velocity of the ball and its pitch is also subject to continuous change as the ball rotates. Angle of attack, and cross-sectional area are both important determinants of the ball’s aerodynamic coefficients and were accounted for in the model.”
Flight analysis
The model used peer-reviewed wind tunnel studies on rugby balls at different angles
of attack to the airflow. Rugby balls were also kicked inside a large aircraft hangar (to avoid the effects of wind), and the real trajectories were compared to the trajectory model predictions.
The model was found to have high accuracy and various in-game scenarios where the rugby ball may leave the field were identified. Data from the peer-reviewed studies were also used to estimate the launch conditions of the ball (speed, angle and spin rate) for different types of player (junior, recreational or professional).
“The sophisticated analysis creates accurate simulations of ball trajectories that can be used to assess the risk of a rugby ball passing a site boundary,” Professor James says.
“Furthermore, where risks have been identified, the trajectory simulations can determine the height of the ball as it passes the site boundary, and thus inform decisions about potential requirements for ball stop mitigation.
“We believe that this highly innovative and technical service is providing significant value to sports facility managers and developers.
“The experimentally validated trajectory model simulations are ‘state of the art’ and the analysis provides a clear indication of what ball stop mitigation may be required and aids the stakeholders with objective information.”
Now in their sixth year, the annual SAPCA Awards celebrate exceptional achievements by SAPCA members within the sports, play and physical activity sectors. Entries are accepted for construction projects, technical innovations, new products and services – and any other successes by members.
