video Water Rocket 2-Liter compressed air
I made this rocket and launcher which uses a 2 liter bottle as the rocket body and and compressed air and water as the propellant. I was able to get the rockets up about 500 feet and even shot some on-board aeial footage. This is not a new idea. I have seen several before. But this one combines the best features of many designs and incorporates some of my own improvements.
here it is if you just want a direct link
http://www.instructables.com/id/Awesome-Water-bottle-rocket-launcher/
For the rocket all you need is a 2-liter bottle. I taped on plastic fins. Here again, you can use whatever you have availible.