Ball's Circumference

[thefro526]

Has anyone measured any of the balls at competition to see what the actual variance is? They didn't seem to vary too much to me, but then again I can't really eyeball differences in circumference that well.

For design purposes though, I averaged out the Soccer balls to have a 8.75" diameter, which is about a 27.5" Circumference. This worked well for me, as competition soccer balls should vary less than 3/16" +/- from this 8.75" Dimension.

[tim-tim]

Originally Posted by thefro526

Has anyone measured any of the balls at competition to see what the actual variance is? They didn't seem to vary too much to me, but then again I can't really eyeball differences in circumference that well.

For design purposes though, I averaged out the Soccer balls to have a 8.75" diameter, which is about a 27.5" Circumference. This worked well for me, as competition soccer balls should vary less than 3/16" +/- from this 8.75" Dimension.

No I didn't measure them, but I can tell you that as the competition went on the balls got "weaker." At the beginning of the day (Match #2) the balls were well inflated (not 9psi by any means probably at 8psi), but by Match #20 they had deflated a considerable amount. From our testing at the shop proved that ball pressure would be such a big factor in its trajectory we had to constantly readjust the kicking strength over the competition. They must have re-inflated them each morning because we saw a jump in performance after not touching it from the previous match the day before.

I think part of the pressure issues comes from rough robot play. However, most of it is probably coming from the seams stretching and an over inflated ball.

[James Tonthat]

I worked Field Crew at Dallas, we inflated the balls to a specific pressure and tested the other ones to be approximately the same (doing a bounce and "thumb push" test). There was no "standard" given pressure that was told to us, we used the indicated pressure on the ball and a gauge. But mostly we were looking for was consistency in the balls.

Balls were inflated so that when dropped from shoulder level, would bounce back to approximately waist level.

We tried keeping ball pressures the same as the day went on, would check between matches. Your results may vary, it's up to the your field crew to keep balls consistently and properly inflated.

Edit: Sorry if I'm not to informative, I'm about to leave for class. I'll elaborate later.