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Since 1970, Adidas has used the design of the World Cup ball to showcase the latest advancements in design and technology. After decades of tweaks to the classic 32-panel design, 2006 brought an unprecedented 14-panel ball glued together with heat. No longer stitched by hand, the marble-like +Teamgeist ball was the most symmetrical sphere to date, attempting to create more predictable results in play. The resulting outcry proved otherwise. Blasted for behaving like a beach ball, players were thrown by erratic swerves of the ball, course changes mid-flight and unpredictable swerves that had goalies grimacing. The next tournament’s ball, the Jublani, proved to be no better.
With the same thermal bond technology used on this year’s Brazuca ball, will we see the same lack of control and ball-related berating from players?
Adidas would probably say ‘no.’ A study done at the Centre for Sports Engineering Research at Sheffield Hallam University suggests the sports giant may have finally solved the dilemma, and it all comes down to physics.
A quick physics lesson that will help explain why: Any object travelling through the air creates different amounts of wind resistance and drag based off of its shape. A perfectly smooth surface allows air to hug the surface and release quickly, while a ball has more edges to catch the air. The lower the speed, the smoother the air can flow over the ball, creating a large wake that results in drag. At higher speeds, the air is more turbulent and can stick to the ball longer, creating less air trailing off as a wake, and less drag in flight.
There’s a big difference in air flow and drag at low speed (left) and high speed (right) (Photo: Courtesy of Carré, M.J., Goodwill, S.R. and Haake, S.J. | Journal of Mechanical Engineering Science)
It’s here where we find the most important feature to how a ball plays: its seams. The uneven texture of seams allows for a ball kicked at lower speed to generate air turbulence that allows the ball to travel with a smaller wake and less drag – more similar to a smooth ball kicked at higher speed. The seamless technology of the +Teamgeist and the Jublani (used in 2006 and 2010 respectively) reduced the depth of seams to nearly half that of a standard ball. This smoothness created more drag, even for a higher speed kick, and affected both the length of the kick and the precision of the player’s aim.
With the Brazuca, Adidas takes a step in the opposite direction, with seams that are 50% deeper than your average 32-panel ball. This groov-y addition may make this ball the most accurate the World Cup has ever witnessed, or it may spark another controversy as players adjust to a different “ball feel.” We’ll simply have to wait for the games to see how this controversy does or doesn’t take flight.
Watch the rigorous testing every ball receives at the Adidas headquarters here.
