The Air Water Rocket Launcher!!!!!!

this simple and cheep rocket launcher uses NO EXXPLOSIVES , only water and air pressure and is made with PVC pipe.
if you want to build it click http://www.thisoldhouse.com/toh/video/0,,20263020,00.html for a video
if you want instructions, click http://www.thisoldhouse.com/toh/how-to/intro/0,,20258045,00.html  
have fun!