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Unread 13-01-2017, 11:05
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Mike Schreiber Mike Schreiber is offline
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FRC #0067 (The HOT Team)
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Re: How Spin Affects Fuel Trajectory

Quote:
Originally Posted by JohnFogarty View Post
In designing a flywheel shooter with my students I've come across something I'm sure many of you have or will discover. Spin causes some pretty weird things to happen to the fuel as they are in flight to their destination.

What I'm looking to do is increase consistency in my shots and I've already got pretty tight control of the RPM of the flywheel.

This suggestion was mentioned by another mentor that works with my team and I wanted to pass it along for thought and clarification as I work today.

Apparently when you use a flywheel shooter with just the the a backplate as the arc/curve you lose some of the energy and get less consistent flight paths with the balls because some of the energy you are trying to impart on the ball as kinectic energy is lost as rotational energy....ie spin on the ball. So the idea is instead of having a curve of plastic you instead have a arc made up of a bunch of small wheels, rollers, something of that sort so that you balance out the rotational energy and the ball simply flys up with no backspin....which could be a good thing especially with the fuel balls. The only reference design where I noticed a team had thought of this and were succesfully able to counteract the spin from their flywheel was team 1717 in 2014.

https://www.chiefdelphi.com/media/im...fe76bdff_l.jpg

I'm not an ME so I hope I'm not explaining things too incorrectly, but I thought this was interesting.
Traditionally teams will intentionally put backspin on a ball to get more air time without the ball dropping into the goal. The spin energy you're putting into the ball helps create lift on the ball due to the magnus effect. This can help to increase shooter accuracy when aiming in a vertical hole in the wall because you have a flatter trajectory. Shooting into a horizontal hole with a ball that has holes means your mileage may vary.
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Mike Schreiber

Kettering University ('09-'13) University of Michigan ('14-'18?)
FLL ('01-'02), FRC Team 27 ('06-'09), Team 397 ('10), Team 3450/314 ('11), Team 67 ('14-'??)
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