World cup ball gives goalies a tough time
15 June 2006
The 2006 World Cup has kicked off with the most high-tech ball ever used. Its innovative smooth design means more players will be bending it like Beckham. But goalies are criticising the ball, and a UK sports scientist agrees. Antenna tackles the issue...
The 2006 World Cup match ball is a top scorer for technology. The designers, adidas, believe it is the roundest, most consistent and most accurate football ever developed. With a radical design made up of just 14 panels; it is much smoother than the 26- or 32-panelled traditional footballs. |
But the ball has been criticised by the England and Germany goalkeepers, and a sports scientist from Bath University believes he knows why the smooth design is giving goalies a tough time.
'We've known for some time that the seams on a football affect its aerodynamics - providing a roughness which improves the ball's stability. Fewer panels mean fewer seams - and a lower stability for the ball in flight.' Ken Bray, soccer science expert, Bath University
Ken Bray, soccer science expert, Bath University
Image: Ken Bray
The ball - named Teamgeist, which means 'team spirit' in German - is made from specially designed curved panels bonded together using heat. Stitching was dropped from World Cup balls in 2002 because it sucks up water, affecting performance. |
The ball was put through its paces at Loughborough University and passed with flying colours. |
Roy Jones, professor of sports technology, Loughborough University
'The Teamgeist ball was scrutinised under all of the present FIFA rules. There are seven tests for top level balls. The Teamgeist football exceeded all of these comfortably. It is undoubtedly superior to the last World Cup football.' Roy Jones, professor of sports technology, Loughborough University |
'But there are no FIFA regulations for testing the aerodynamics of a football. With fewer panels, this year's ball is aerodynamically closer to a baseball, which has only two panels. When it is hit with a slow spin, it will become more unstable, making it hard for players to predict how it will move.'Ken Bray
In baseball, pitchers can throw 'curveballs', which swing in the air like one of David Beckham's bending free kicks might. When a ball is kicked or thrown with spin, the seam disrupts the airflow around the ball, causing it to swerve in one direction.
Occasionally though, pitchers will throw a 'knuckleball' which bobs about randomly in flight and is very tricky for batters to hit. This happens when the ball is thrown with very little spin.
'As the ball rotates lazily in the air, the seam disrupts the airflow around the ball at certain points on the surface, deflecting the ball first in one direction, and then another.'Ken Bray
The seam moves in and out of the airflow randomly, causing the ball to move in different directions unpredictably. But for this to happen, players must strike the ball perfectly, causing it to spin very little. This trick is a lot easier to achieve in baseball than it is in football. |
It is these football equivalents of a 'knuckleball' that Ken Bray thinks will bamboozle goalies: 'With the world's best players in Germany this summer, there are bound to be plenty of spectacular scoring free kicks.
'But watch the slow motion replays to spot the rare occasions where the ball produces little or no rotation and where goalkeepers will frantically attempt to keep up with the ball's chaotic flight path. They're also much more likely to punch these balls away, rather than trying to catch it.'
The Italian goalie, Fabio Cannavaro, fights for the ball with Ghana's Richard Kingston.
Image: Action Images Limited
'The Teamgeist football tends to be more unpredictable than previous World Cup balls, veering out of its predicted path. I expect we'll be seeing lots of nail-biting goals as the tournament progresses.'Scott McKenzie-Cook, captain of the Science Museum football team
Scott McKenzie-Cook, captain of the Science Museum football team