[Aur0r4]

As a point of clarification, when we used the term density, we were referencing the density of the foam matrix and its effect on the ball's stiffness. This has a direct impact on the behavior of the ball in most pitching machine style shooters. We didn't weigh them, but it stands to reason that the balls with a denser foam might weigh more.

For our purposes, and most teams with a rotary shooter, the stiffness changes will produce a greater variation than will the mass changes as it can be thought of as a change in the interference between the ball and the rotating mechanism. From our test, we discovered that the variations in density could be equivalent to a nearly half inch change in our wheel spacing!

We also agree that FIRST demands robust design, and these variables add to the fun! However, to appropriately design a solution, one must first have a solid grasp of the problem. In this case, we are hoping teams can help develop an idea for how the stiffnesses of the balls could vary at the competition.