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Unread 01-02-2017, 16:11
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Re: pic: Spectrum 3847 - 2017 CAD Model: Gamma Ray

Quote:
Originally Posted by EricLeifermann View Post
I don't know what we were spinning them at accurately but it was faster than 6000. The problem wasn't that the expansion was affecting the shots, its that I wasn't comfortable safety wise with the expansion. We were also using 2in roller over a 1.5 aluminum tube, so maybe the smaller diameter doesn't expand as much was we saw with the large.
Centrifugal acceleration* = w^2 * r. More RPMs and more radius = more force expanding your tube. Since this acceleration applies to all of the tube, thickness won't matter, aside from the smaller force on the ID of the tube. The only material property that matters is some sort of ratio of density and elastic modulus, but that'd be the same since ou said it was the same stuff.

So all in all, not surprising your tube wanted to expand more than Spectrum's. Are you guys going for a longer shot to need that much more surface speed?

*Yes centrifugal. Pedants are welcome to spend 15 minutes drawing a FBD with a tangential velocity, required change in velocity to create a circular path, implied acceleration, unbalanced force to create that acceleration, etc, etc. I'm going to pretend it's a real force and get on with my life.
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Last edited by Kevin Sevcik : 01-02-2017 at 16:19.
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