For me it all started with a small plastic launcher that used to be sold by that wonderful place that every hobbyist should know about, American Science and Surplus (once known as Jerryco), for around 10 dollars. The same launcher, called a POP FLIGHT launcher, is also sold by Apogee Components, a model rocket supplier. The catalog copy said I could make a water rocket from a plastic pop bottle: that sounded like a fun little diversion, so I ordered the thing on a whim. When it arrived, I innocently took it out to my tiny San Francisco backyard, put some water in a 2 liter bottle, clamped it on the launcher, pumped it up to 40 psi or so, and yanked the string. I wasn't quite ready for what happened next...
The simplest kind of rocket doesn't really require a launcher at all, just some way to prop the bottle in position while you pump. This kind of rocket is made by simply stuffing a rubber stopper in the neck of the bottle, inserting an inflation needle through a hole in the stopper, and pumping it up until it blows! You never quite know when it's goiing to go, which of course adds to the excitement (kids love this). There's lots of good information on this sort of launch technique at the Interplanetary Water Rocket Society home page, maintained by Gordon McDonough in Santa Fe, New Mexico.
Summer may be officially over, but that doesne’t mean that you cana’t still play outside. Need some motivation? How about the Aquapod Water Bottle Launcher. Itr’s the first professionally manufactured bottle launcher on the market that can launch a 2-liter plastic bottle up to 100 feet in the air. Get yours for $24.99. Full press release after the jump.
Unlike other bottle rocket launchers, launching the Aquapod is simple—it requires no assembly and is easily portable. To launch, fill an ordinary 2-liter plastic bottle 1/3 full of water, place it over the launch tube, and secure the latch. Attach a bicycle pump to the front air valve, and give 10 to15 pumps or until the check valve releases. Moving back 15 feet to the launch position, pull the trigger lanyard with a short, quick tug to release the bottle. Watch it soar up to 100 feet in the air.