The official ball for the 2014 FIFA World Cup in Brazil has a stable flight trajectory thanks to the shape and number of panels that it is constructed from, a study in Scientific Reports indicates. An analysis of different soccer balls shows that the characteristics of panels on a soccer ball have a substantial impact on how the ball travels through the air.
Traditionally, soccer balls are constructed from 32 pentagonal and hexagonal panels, although newer balls produced from 32, 14, and eight panels with shapes and designs dramatically different from those of conventional balls. The newest type of ball has been produced from just six panels and will be used in the 2014 FIFA World Cup in Brazil. Few studies have investigated how different panel formats affect the aerodynamic properties of balls, a question that Sungchan Hong and Takeshi Asai now address.
Wind tunnel tests reveal that drag (air resistance) varied with panel orientation and show that drag is lowest for the six-panel ball, followed closely by the conventional 32-panel ball. When the balls were kicked by robots the authors observed that the trajectories were substantially affected by the orientation of the panel, implying that the panel orientation significantly affected the flight. The six-panel and conventional 32-panel balls displayed relatively stable and regular flight trajectories relative to the other balls.
Other factors affect the aerodynamic forces acting on a soccer ball, such as the surface roughness and material, the bonding method, and the symmetry of the panels, the authors note. They suggest that effects of these other features would need to be clarified in a future study.
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