Re: How to build a launcher out of PVC pipe and no propellants

Dear User,

An obvious solution would be to use compressed air. One of the relatively 
simple designs would be to borrow a locking mechanism from the 
water/compressed air rocket. You probably can use a bike pump to develop 
sufficient pressure, provided that your cannon fits the tennis ball tightly 
enough.

Other than that, I guess you could try to make a slingshot type device, by 
cutting two parallel slits through the sides of the "cannon" and passing a 
tight rubber band through them, affixing it at the upper part of the tube, 
roughly like this :


fix here->==============
------------------------=           -----   <-tube with slits 
                        *=
                       ***=   ----> pull to load
                        *=
-----------------------=            -----
and here->=============

 *
*** tennis ball
 *

Hope it helps,

A.G.E.