Investigation of toppling ball flight in American football with a mechanical field-goal kicker
A mechanical field-goal kicking machine was used to investigate toppling ball flight in American football place-kicking, eliminating a number of uncontrollable impact variables present with a human kicker. Ball flight trajectories were recorded using a triangulation-based projectile tracking system to account for the football’s 3-dimensional position during flight as well as initial launch conditions. The football flights were described using kinematic equations relating to projectile motion including stagnant air drag and were compared to measured trajectories as well as projectile motion equations that exclude stagnant air drag. Measured football flight range deviations from the non-drag equations of projectile motion corresponded to deficits between 9 and 31%, which is described by a football toppling compound drag coefficient of 0.007 ± 0.003 kg/m. Independent variables including impact location and impact angle orientation resulted in 15 impact conditions. We found that an impact location of 5.5 cm from the bottom of the ball maximized trajectory height and distance. At the 5.5-cm impact location, alterations in impact angle produced minimal change in football trajectory, including launch angle (range = 1.96 deg), launch speed (range = 1.06 m/s), and range (range = 0.94 m).
KeywordsKicking Football Drag Place-kicking American football Trajectory
This research greatly benefited from the help of our research assistants, Andrew Palmesano, Margret Clay, and Jesse Lin. We would also like to acknowledge the Nebraska Athletic Performance Lab and the Athletics Department at the University of Nebraska-Lincoln for providing the laboratory space necessary for performing this study. This work was supported in part by the National Science Foundation through award PHY-1505794(TJG).
Compliance with ethical standards
Conflict of interest
The authors have no conflict of interest.
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