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Unread 09-01-2012, 09:00
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Michael Hill Michael Hill is offline
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Re: Drag coefficient of 2012 Game Piece

I just did some back of the envelope aerodynamic calculations for the game piece this year and realized we're RIGHT on a near asymptote when trying to predict drag on a ball. (Hey, I'm bored at work with nothing else to do.)

I estimated the Reynolds number to be around 120000 (assuming around 10 m/s) and the relative roughness factor to be around 4.9 *10^-3 (I assume 1 mm dimples with an 8 inch ball, best I can estimate without having the game piece in my posession).

Then I found this little jewel (see attachment):

As you can see, the roughness (epsilon/D) line for 5*10^-3 has a nice little vertical right around Re=120000.

This doesn't take into account any spin, mind you (and I really don't feel like getting into Magnus Effect forces right now).

Enjoy!

P.S. In my opinion, the dodgeball couldn't be any more imperfectly designed if consistancy is desired.
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