How to Make a 250 ml Water Bottle Rocket
- 1). Secure and empty a 250 ml plastic bottle. This is a type of bottle used for soft drinks or water. Discard the cap, you won't need it anymore. Set the bottle aside.
- 2). Cut two lengths of 7/8-inch PVC pipe. The first length should be 5 feet long, and the second length 2 feet. Smooth the edges to remove any burrs. Attach the two pieces together with the 90 degree pipe angle, using your PVC pipe cement. Coat each interior section of pipe with the cement, and then connect the pieces. Allow full curing time for the pipes to seal.
- 3). Drill a hole on the inside of the open end of the longer piece of pipe of the appropriate size to hold your bicycle tire valve. You can get the bicycle tire valve by cutting it out of bike innertube, leaving a 1/2-inch flange of rubber around the base of the valve. Insert the valve into the pipe from the inside out. Caulk the surface of the rubber flange and press the valve securely through the hole. Seal the outside with caulk as well, and allow full curing time, to ensure an air-tight seal. It's best to use a presta-style valve, since these come with a locking nut that will give the valve an extra measure of security when it's fastened into the pipe. When the valve is secure and the caulk set, glue the pipe closed on that end with the pipe stopper and PVC cement.
- 4). Using your 2 by 4 lumber, build a base that consists of a 5-foot length of 2 by 4, with two 1 1/2-foot crosspieces underneath at either end. Using the duct tape, secure the PVC pipe assembly's long end to the 2 by 4, so that the short end sticks straight up into the air.
- 5). Attach electrical tape to the vertical section of pipe, about two inches down the pipe from the top. Slide the bottle over the pipe and test the fit. The opening of the bottle should fit snuggly over the electrical tape so a good seal is made.
- 6). Attach your pump to the PVC assembly. Now fill the bottle about half-way full of water, and invert it onto the vertical pipe, and snug it down against the electrical tape seal. Clear spectators away from the area, and begin pumping the bicycle pump. When the pressure gets too high, the rocket will take off. Experiment with different amounts of water in the bottle for the best results.
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