Tennis Ball Launcher trouble

[Deadeye]

A friend and I tried making a tennis ball launcher out of 3 feet of pipe
about 3 inches wide (see attachment), we stuff whatever we want shot out
into it, then add a capful of camping stove fuel. Sometimes we can get a
nice "thoomp", but it doesn't launch our projectile?? What are we doing
wrong?? Can anyone help us??

--

Deadeye
************************************************************
Please reply to my e-mail address, if asked, 'cause I'm lazy.
Take out *SpamBgone* in e-mail address
************************************************************

[Greg]

Try warming the fuel to just before its flash point the vapor will have
a better compression also I had a friend ad black powder to the mix
useing the camping fuel as an ignitor good luck and start slow. Blowing
things up is fun blowing your friends up is only funny until the heal!