Whether for a school science project or just for family activity on a sunny afternoon, building a water bottle rocket is an enjoyable way to learn. This water bottle rocket can reach heights of nearly 75 feet in the air using an ordinary bicycle tire pump. Some other methods suggest using an air compressor to propel the water bottle rocket, but using a bicycle tire pump is safer for children and easier to complete.
Create the launch pad for the rocket by inserting the ¼-inch metal rod into flat, level ground. Choose an area away from any trees that could obstruct the launch.
Drill a small hole in the rubber stopper, just large enough to insert the needle from the bicycle tire pump. Attach the needle to the end of the pump and place the needle through the stopper.
Tape the straw vertically onto one side of the bottle using duct tape, in order to create balance for the rocket.
Cut three right triangles out of the construction paper using the scissors and duct tape them onto the upside-down plastic bottle. These will serve as the fins on the rocket and should be four to six inches long on the longest side. You can also make a cone out of the paper and tape that to the top of the rocket.
Fill the soda bottle approximately half full of water. Use trial and error to determine if you need more or less water for your rocket.
Insert the stopper into the open end of the plastic bottle with the needle inserted through the stopper. Stand the plastic bottle up on the end of the metal rod.
Begin creating pressure inside the bottle by pumping with the bicycle tire pump. After enough pressure is built up in the bottle, it will shoot up into the air leaving a trail of water behind it.
If you are doing the pumping, be prepared to get wet when the rocket launches.