"Pitching Machine" motors

[Djur]

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.

Originally Posted by EricLeifermann

You can get backspin with just 1 wheel...

Yes, but that results in less ball energy at the same launch speed. There's the extra friction given by the cowling and the lack of energy from a second wheel. If you're aiming to hit a goal from a distance with any accuracy, you'll need to have more energy in your system to hit from ~20' or more than a single CIM or similar motor can supply.

Also, this.

[Jeffy]

Originally Posted by Mk.32

Some examples of that would be nice ^^

Well, it was a bit of trick question. Using a sort of flywheel setup, a system could have any amount of energy as long as the flywheel fit in weight and size requirements.

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!

[dellagd]

Originally Posted by Ninja_Bait

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.

Doesnt that all depend on how much backspin you want? Elaborate please.

[Djur]

Originally Posted by dellagd

Doesnt that all depend on how much backspin you want? Elaborate please.

If you have 2 rollers spinning in opposite directions (clockwise and counter-clockwise) with the higher roller spinning slightly slower than the bottom one, you'll get backspin because the 2 rollers both give energy to the ball. If you had just the bottom roller and a hood, you'd still get backspin, but that's because of the friction of the hood keeping the top of the ball from spinning as easily. So basically two rollers are better than one + hood because of more power given to the ball and less power needed (you don't need to overcome friction).

[Ninja_Bait]

Originally Posted by dellagd

Doesnt that all depend on how much backspin you want? Elaborate please.

It's time for a free-body diagram explanation.

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.

[EricLeifermann]

Originally Posted by Ninja_Bait

It's time for a free-body diagram explanation.

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.

Have you seen some of the shooters from 2006 with only 1 wheel? They could shoot pretty far, the only thing keeping them from shooting as far as they could was the speed limit the had that year...