NOTE: Although the instructions for the water rocket are finished, this page about history and design of water rockets is still under construction.
SODA BOTTLE WATER ROCKET HISTORY DESIGN, AND LINKS (also check out___________)
Although played with a water rocket toy when I was a kid (1960s) as far as I know it was some inventors at the Mother Earth News (a homesteader, back-to-the-land, alternative energy and occupation magazine) who first hit upon the idea of launching soda bottles in 1983. http://www.motherearthnews.com/diy/1983_July_August/Mom_s_Two_Liter_Bottle_Rocket They were apparently developing a garden sprayer (which uses compressed air and liquid) from recycled materials when someone wondered what would happen if the pressurized bottle broke loose. Hats off to those terrific inventors! That short article got me and a whole lot of other people started developing water rocket launcher designs.
That original design used the half-inch PVC pipe, too. Although I have read about and tried launchers that use--for example--a rubber stopper and no pipe going into the bottle, I don't trust them. I like the idea of a pipe guiding the bottle where pipe is aimed. Sure, I know it's only for a few inches, but at least I know it's off to a good straight start. The pipe in the bottle could be faulted for not allowing the air to bubble through the water in the bottle during the air-pumping stage, but there is a fix for that below________________________
Back to that original Mother Earth News design, it wasn't perfect. It did have a very clever but simple seal: a common garden hose washer at the base where the pipe poked through the launch platform. The problem was that you had to hold the bottle onto the hose seal really really hard, or it would leak. In their design a bare, bent welding rod held the bottle on and they claim it could get 50psi in it before it leaked. I suspect there must have been a lot of trial and error to get that good a result. And when they say in the article that launching is, "...of course is a two-person job. Indeed, with one youngster pumping and another handling the release cord..." when I read between the lines it sounds like one person is pumping furiously and the other launches before all the water has leaked out! Also--and maybe I'm just a big dummy--but I had a harder time using parachutes with with water rockets that the article suggests. Unless the rocket is launched with pretty low pressure, the parachute comes out prematurely or not at all. And if the chute gets wet, it sticks to itself and everything else. I've got some links to people adding parachutes to water rockets in links below, but just understand it's very challenging stuff.
My first really successful launcher was similar to the Mother Earth News design but used a split wedge to press the bottle really hard on the seal. We were able to get much higher pressure
To learn how to hurl water balloons out of site, click here
To see the links to the best water rocket web sites I've found--including slow-motion launches, aerial photography and multi-stage rockets click here.
For a frank discussion of the safety issues involved with water rockets, click here
To learn about Newton's laws of motion that make water rockets work and to calculate how high they go under construction
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