Building a Projectile Launcher: Rubberband, Spring or Catapult?

[helpwithphysics]

I have a question- How exactly should I go about building a projectile launcher with a ping pong ball?

Would you recommend a catapult launcher, a rubberband launcher, or a spring launcher?

Thanks.

 

[helpwithphysics]

I Need Help Please.

I'm pretty sure that I'm building a rubber band launcher.



How would you assemble this?

 

[rcgldr]

There are table tennis practice machines, the cheap ones use air, but the good ones use two wheels, similar to a baseball pitching maching. The two wheels are driven by dc motors, and and run forwards or backwards independently so that extreme backspin or top spin can be generated.

http://www.megaspin.net/store/default.asp?cid=robots&scid=butterfly&pid=b-amicus-3000-p

 

[Mk]

Can you give us a little bit more information including:
time period
money
class you are taking, unless it is for fun
means for propulsion

You could built a nice rubber band and catapult hybrid with PVC, having the armature as-pulled-back increase tension on many rubber bands (thick, or even another material). When the arm is let go of, the elastic potential will release and catapault! WHOOO!

 

[helpwithphysics]

Thanks, its for a regular physics class, just for fun. We just need to have the ping pong fly accurately.
Great Ideas! Thank you

 

[Danger]

For accuracy, I'd recommend something along the approach that Jeff mentioned. Top or bottom spin should keep the ball going pretty much in a straight horizontal trajectory. Your elevation can be adjusted by varying the speed or the vertical angle of the launcher. Side spin would make it curve, and probably not with acceptable accuracy.

 

[Mk]

Just get a small motor out of an old computer's fan or something like that to drive the wheels. If that is too complicated you could put a spring in the bottom of a tube, put the ball in the tube, and push down on the ball, then let go.

 

[Farsight]

Get a vacuum cleaner. One that blows as well as sucks:

http://shinyvacuumcleaner.en.alibaba.com/product/50009348/50041996/Vacuum_Cleaners/Mini_Vacuum_Cleaner.html

 

[Mk]

That's the n00b way.

 

[rcgldr]

If you use a hose with air blowing through it, you can place a rubber band on one side of the opening to impart spin on the ping pong ball. You'd want the rubber band on the top to generate backspin.