How to control spin of a launched ball

[Nicholas Bunker]

Hello, i have to launch a ping pong ball for an engineering course. We have a system set up with two wheels spinning as fast as we can get them and a ping pong ball feeds between them and shoots. Our asignment is to create a model that shows distance shot related to the angle of launch. We also will have a competition where we try and hit the other team. The distances are short so we could decrease the speed of the wheels but because of the nature of the conpetition we want to get as much force out as possible. We also don't want to hit line drives at people because that would defeat the purpose. So my question is, what is the best way to create topspin so we can increase speed but decrease distance traveled. Much like tennis, but much more violent. Should we create a high friction point directly beneath the ball between the spinners? Slightly forward of the spinners? Advice please thank you in advance

 

[JBA]

You might try replacing the lower spinning wheel with a fixed flat surface.

 

[billy_joule]

Or gear the wheels so the top wheel is spinning faster than the bottom. Or have a motor on each wheel running at different speeds.

How do tennis ball machines do it? (Assuming they do do it)

 

[Nicholas Bunker]

Our wheels are horizontal :/ i will look into tennis machines thank you.

 

[Mech_Engineer]

As others said if you reconfigure your machine to have the wheels oriented vertically, adjusting the relative speed of the top vs. bottom wheel should induce spin on the ping pong ball.

Edit: This might be difficult to model, will you be expected to have a model showing how spin will effect the ping pong ball's flight?