This instructable will show you how I made my monstrous tennis ball launcher (cannon) from mainly scrap metal and just a few things from eBay. Also included are tips and potential improvements for certain areas in both design and construction. And of course, how could I nearly forget, how to have lots of fun with it.
Propulsion source: Compressed air from compressor or foot pump (depends how lazy I’m feeling)
Barrel dimensions:90mm OD x 70mm ID x 500mm
Main ammunition: Tennis ball
Max distance of main ammunition: 100m
Secondary ammunition: anything you can stuff down the barrel with wadding at bottom
I first came up with the idea of making a tennis ball launcher to help enthuse school children (year group 9) about mathematics by getting them to aim for a target on the ground behind a wall of paper so that they had to use complex equations and mechanics principles. I did think about making a ping pong ball launcher to the same general design but scaled down as this would have been cheaper and easier, but then I thought that it would be much more fun for them to use a cannon outside. Using this instructable you could still make the ping pong cannon, but what says I love my dog more than a tennis ball cannon strapped to the roof of your car in the dog park car park.
At the end of the instructable I will include the relevant equations of motion that i hope to be able to teach the year 9's. I will also include a link to a simulator that also accounts for drag .