Modelling the ‘run-out’ Throw in Cricket

In cricket a ‘run-out’ can occur if fielders return the ball whilst batsmen are temporarily out of position. This may involve a throw to the wicket keeper or a direct hit on the stumps. Time of flight is important and this is determined by astute control of the release parameters, ball speed and elevation especially. These variables were investigated by monitoring a series of throws from 20 to 40 metres, performed by experienced cricketers in an indoor sports hall. Throwers achieved greater distances by increasing both the speed and elevation at release, but increasing the elevation was the preferred way of extending the length of throw. Aerodynamic effects associated with the ball’s raised seam are also important as they can affect the throwing accuracy. Unwanted deflections can be avoided if the ball’s seam is ‘scrambled’ i.e. rotated rapidly in flight. Elite cricketers achieve this by throwing with backspin, but the results show that aerodynamic drag is increased in the process. Spinning the ball does produce aerodynamic lift, however, and modelling the flight confirms that this lift is essential in achieving the required carry, especially for the longest throws.