Trackballs

[smurfgirl]

Originally Posted by Uberbots

according to my calculations, the mass of the air in the ball is about 1.5 pounds (at stp)... which is actually pretty significant.

either way... any progress on where to purchase the balls yet?

I know that additional parts are available at IFI's online store... wouldn't the game pieces be available there?

[AndyB]

Just give it some time. I'm sure FIRST will point out a carrier if IFI doesn't end up carrying it. Just give it some time. You don't really need a ball for another few weeks yet to be honest. At least until you get prototyping.

[artdutra04]

Originally Posted by AndyB

Just give it some time. I'm sure FIRST will point out a carrier if IFI doesn't end up carrying it. Just give it some time. You don't really need a ball for another few weeks yet to be honest. At least until you get prototyping.

I'll bet that the FIRST LogoLoc store will be carrying it this year, since they were the distribution channel for all of the tubes last year.

[cbudrecki]

Originally Posted by Eragon301

Here is a site that will sell 40" gym balls, but its just the blatter, and i have yet to find a site to get the cloth cover.

Are these the same grade PVC as this year's bladders, or are these more like the '04 2X balls?

[cbudrecki]

Originally Posted by TomZ

If at the beggining of the match during the hybrid period, you knock down a ball of the opposing alliance, who recieves the points?

This question has been answered in this thread. Also, READ THE MANUAL. <G08>

[Wayne Doenges]

FYI, a fully inflated ball will bounce 17' when dropped from a third story balcony
I just had to throw this in. Good luck to all.

[razor95kds]

our ball weighed 7.0 pounds before AND after inflation. Our scale is pretty accurate to the tenth digit too (its not a bathroom scale fyi)

[Eragon301]

Originally Posted by tb222

Are these the same grade PVC as this year's bladders, or are these more like the '04 2X balls?

I'm not sure, I couldn't find anywhere that said it, but I'm still looking

[DonRotolo]

Originally Posted by Uberbots

according to my calculations, the mass of the air in the ball is about 1.5 pounds (at stp)... which is actually pretty significant.

1.5 pounds? To clarify, are you trying to tell me that you calculated the weight of about 20 cubic feet of air as being 24 ounces?

That's off by several orders of magnitude. That doesn't even pass the 'reasonable' test.

Don

[Mike Betts]

Originally Posted by Don Rotolo

1.5 pounds? To clarify, are you trying to tell me that you calculated the weight of about 20 cubic feet of air as being 24 ounces?

That's off by several orders of magnitude. That doesn't even pass the 'reasonable' test.

Don

Don,

The answer is quite near correct. actually 22.4 cubic feet of air weighs about 28.8 oz if you assume an 80/20 mix of Nitrogen/Oxygen...

You may wish to clarify or rescind your criticism on this point...

Mike

[DonRotolo]

Indeed, Mike - what I foolishly ignored (to my own detriment!) is that while the air inside the ball DOES weigh several ounces, I forgot that it's immersed in air of similar density and composition, so the DIFFERENCE in weight (which is what I was thinking about) is a very small number (accounted for only by the pressure increase above the air outside the ball.)

I apologize to Uberbots for typing before thinking, and humbly thank Mike for pointing out the error.

No matter who you think you are, you can still get trapped by your own mind. If it really matters, ask a colleague for a reality check.

Don

[Kevin Sevcik]

Does anyone have an estimate of the pressure in a properly inflated ball? 1 atm is about 15 psi. So if the balls are inflated to 15 psi, then the extra air would come out to 1.5 pounds. FIRST's inflation standards are size and not pressure based, so if it takes 10 psi or so to inflate some track balls, then the variances could be fairly significant.

[Elgin Clock]

I found a site that sells balls similar to the trackball, and the 40" balls themselves cost approximately $60 to $110. The covers for the balls cost $45, and the replaceable inner bladder costs $20.50.

Those numbers are just posted by me as reference, and not to be taken for anything other than reference at this point.

I WILL NOT provide a link to my source until the official source of the balls is made public, so you will just have to trust me on this one.

[Francis-134]

Originally Posted by Kevin Sevcik

Does anyone have an estimate of the pressure in a properly inflated ball? 1 atm is about 15 psi. So if the balls are inflated to 15 psi, then the extra air would come out to 1.5 pounds. FIRST's inflation standards are size and not pressure based, so if it takes 10 psi or so to inflate some track balls, then the variances could be fairly significant.

At the kickoff, the balls were inflated to the point that the cloth cover was completely taught with no wrinkles on any of the seams. This is also what the manual says.

When we inflated our ball, everyone thought that it would break well before it reached full inflation. However, the ball reached the proper size without any problems. We were even able to press on it a small amount without it breaking. I've seen a lot of pics on CD lately with people that seem to have under inflated balls. To be blunt, don't be shy about inflating those balls!

[Elgin Clock]

Also, one more thing should be noted about the balls that is worth some interest.

The zipper head should be under a flap of fabric when you inflate your balls and zip up the outer Red or Blue cover. If it is not, then you did not turn your ball's cover inside out, and put it on correctly.

The ball covers were shipped to you in the "inside-out" position.

Just make sure your zipper is hiding under the flap when it is closed, and you should be golden.