Help With Tennis Ball Launcher?

[Penguin10]

My partner and I are making a tennis ball launcher for a physics project. We are going to use either a bungee cord or spring inside of pvc pipe. Do you have any ideas for how to set up the device on the inside? Also, we were going to use a camera tripod as a stand, but are skeptical on if it will tip over or not. We might make one out of wood, but the angle would not be easily adjustable as if we were to use the tripod. How could we adjust the angle and set up the launching device inside? Also, the device needs to be triggered from a distance. No combustion or pneumatic devices are allowed either

 

[Delphi51]

One possibility is to use a second pipe that fits inside the first to push the ball. Then you could use springs or bungees outside the pipes to pull the small pipe inside the large one.

Would a long string attached to a pull pin be considered remote control?

 

[Penguin10]

One possibility is to use a second pipe that fits inside the first to push the ball. Then you could use springs or bungees outside the pipes to pull the small pipe inside the large one.

Would a long string attached to a pull pin be considered remote control?

I'm not sure what you mean by a second pipe inside of the first one. We also would prefer the spring or bungee cord to be inside the device. I think remote control would be a battery operated device, like the ones you see with remote control cars. We will probably use a long string and pull pin since it is one of the easiest to make and effective triggers