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Unread 06-02-2012, 02:51
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VEX Robotics Engineer
AKA: Arthur Dutra IV; NERD #18
FRC #0148 (Robowranglers)
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Re: Top/bottom roller shooter vs. bottom roller only

Quote:
Originally Posted by wireties View Post
But our "car" is not moving. The speed on the edge is r * omega where omega is rps * 2 * pi. If there is a second wheel above the first why would it increase the speed on the edge of either wheel? Perhaps the real issue is that single-wheeled shooters lose velocity because of the balls interaction with the hood? And double-wheeled shooters (which generally have no hood) do not?

Jeez - I should have paid more attention in physics but I don't get it. How could you possibly accelerate the ball to an initial speed greater than the speed on the edge? Happen to know any illustrative web sites?

TIA
The problem is very simple.

With single wheel shooters, the ball has to roll along the hood. When you make the edge of a rolling object move at 1x ft/sec, the object as a whole moves forward at 0.5x ft/sec.

With double wheeled shooters, the ball is just pushed through the two wheels. It doesn't have any backspin and leaves at a maximum velocity of 1x.
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Art Dutra IV
Robotics Engineer, VEX Robotics, Inc., a subsidiary of Innovation First International (IFI)
Robowranglers Team 148 | GUS Robotics Team 228 (Alumni) | Rho Beta Epsilon (Alumni) | @arthurdutra

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