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"Pitching Machine" motors
Has anyone had any good results shooting the balls a good distance accurately using any of the allowed motors other than the CIM motors? Do any of the other motors provide the required power to shoot at least half way across the field, or are we stuck having to use the CIM motors?
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Re: "Pitching Machine" motors
My team was prototyping this using treaded wheels with a CIM attached to each. We maybe were getting two feet out of them. To be fair the set-up was far from optimal and we've still got to try fiddling with the gear ratios, but initial results aren't that impressive.
Edit: No we haven't tried anything other than CIMs, but even the CIMS were unimpressive |
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Do you need help with the math to find out how much energy it takes to get a basketball X feet?
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Since Work = 1/2 * mv^2 (final velocity) - 1/2 * mv^2 (initial velocity) and Work = Force * Distance, you can find the force can be found if you know the other variables. Use this spreadsheet for specifics including angles and the velocities you need.
So say you're shooting from 6 meters (about midfield) at a 45 degree angle at the top hoop. Code:
f * d = (mVf^2 - mVi^2) / 2 |
Re: "Pitching Machine" motors
If you took a momentum/impulse approach, do you think you would get the same answer, or would that add other factors in that this solution ignores?
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As a side note: Back in the day ('07 to be precise), when we were trying to throw Poof balls, we were getting an amazing lack of distance, sometimes maybe reaching 6'. This would have been pitiful in competition.
On a whim we decreased the space between the spinning wheels, thus "squeezing" the balls more. Suddenly, we were exceeding 30' on a regular basis, without any other changes to the thrower. Photo of work in progress. Can't find one "proving" the distance, but the turned faces are an indication. |
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Thanks for all the help, guys
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You can get backspin with just 1 wheel...
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It's more efficient with two wheels instead of one wheel with a hood. The loss in momentum is divided over two wheels and the bottom wheel doesn't have to work against as much friction to launch the ball.
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Oh, check out this post that has a spreadsheet to calculate velocities, angles, etc. and try reading this thread that has stuff with torque, speed, and motors in it that address the questions on the OP.
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Also, this. |
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This gets difficult for me to explain without a whiteboard for drawings in front of me, but here is my best shot: What you really want to find out is if you can get a ball moving fast enough to go the distance. The speed at which you need can be solved with basic high school physics using motion formulas. Enlist a student or physics teacher at your school if this isn't making sense. This is often taught as "projectile motion" in the classroom. After you have found the speed you need, gear the shooter to spin at this speed, and off you go. Other things to consider on a shooter: -How much you compress the ball -Weight of flywheel (heavier will keep it from slowing down on shots as much because it will have a higher moment of inertia) -Gripping material (KoP wheels from this year have not wielded good results for me either) -Time and distance of contact (remember force times distance) -Spin Best of luck! |
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Bottom roller + hood: Two forces: the force from the wheel and the force of friction from the hood. both work together to create backspin; friction works against the wheel to create forward acceleration. Top and Bottom roller: Two forces: The wheels work against each other, with the bottom wheel applying more torque to create backspin; the wheels work together to create forward acceleration. So yes, there is a backspin consideration involved here - more backspin would be easier to get out of a hooded shooter. However, the wheel is forced to do more work, so you lose more momentum between shots, and can't shoot as far. |
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