Tuesday, June 13, 2006

teamgeist balls and sports by design

I have recently noticed a number of articles about the aerodynamics of the teamgeist balls and how it can have random meanderings which confuse the goal keeper. Some people even point out how the orientation of the ball is very important for this to happen etc.

Some examples:
cfdreview says
Some of the world’s greatest goalkeepers have been beaten by unusual swerving balls which move to the left and the right before hitting the back of the net, even though they have little or no spin applied to them. The new research has found that the shape and surface of the ball, as well as its initial orientation, is critical in terms of its trajectory through the air.


And the above link also says
A team of researchers, led by Dr Matt Carré at the Department of Mechanical Engineering at the University of Sheffield, used the most advanced software, known as Computational Fluid Dynamics (CFD), for simulating the physics of airflows in and around objects.

Hmm. I thought CFD was a field of study.

BBC seems to have better journalists. Here is their take:
In the early 1950s a young Brazilian midfielder nicknamed Didi invented the swerving free kick. He realised that a ball kicked with spin would deflect significantly in flight.

It is no accident that the technique emerged first in the South American game. The leather ball of that era was very prone to water absorption and the weight increase made it much less responsive to the aerodynamic forces caused by the spin. This was seldom a problem in the warm, dry conditions of Brazil but a serious drawback in Europe's winter game.

Not until a ball with a synthetic, impermeable surface was introduced in the 1960s could the technique catch on. European players then became as adept as their Brazilian masters and a long line of expert free-kickers stretches from Didi to the present day.


I would think that in a sports that is played by 22 people in a large play ground in varying and widely different weather conditions, good sportsmen would already have adapted to these things. Any random air pocket could easily cause a much different flight dynamics. It somehow seems that these kinds of researches are misguided. And sports by design is not very possible. Good players have to adapt to the game conditions and play well (and thats why they are good players, in the first place).

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