It was reported yesterday that Adidas, through the mouth of PR spokesman Thomas Schaikvan, seemed to have conceded that Jabulani behaves differently at the high altitude of some venues. Apparently he said that "… playing at altitude is not the same as playing at sea level. That is just plain science."
Fine, you can't do much about the altitude factor. The problem is that at 3000 meters (e.g. in Johannesburg) the density of air is about 0.9 kgr/m^3.
As in the previous post, assume that the standard size 5 smooth ball (about 0.23 m in diameter) would fly in air at an altitude of 3000 meters (constant r = 0.9 kgr/m^3 and air temperature at 25C) at 90 km/hr (25 m/sec) then the Re would equal:
Re = 0.9 * 25 *0.23 /1002e-6 = 5.2e+3
That is quite a bit of difference versus Re at sea level and the ridges would cause a different behavior. You add the possible effects from some weight variation (recommended air pressure is 11.6-14.5 psi) and the ball trajectory would be quite a bit different from one game to the next!
Thomas Schaikvan also mentioned that Adidas made the ball available to all teams 4 months in advance of the start of the World Cup but most teams did not take advantage of it and did not train with it. Among other things he mentioned: ''We presented the technology and underlined the requirement to get used to it because it is a different ball and a different technology.''
I guess my question is:
When did it become a requirement to adjust the game to a soccer ball? What is next? Adjust the game to Adidas-made rubber goalposts?
Related articles:
TribalFootbal.com: Adidas claim altitude not ball design responsible for keeper errors
The Sydney Morning Herald: Adidas says it warned teams about the Jabulani
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