1. Build the stomp rocket launcher by inserting the mouth of the two-liter bottle into one end of the pool noodle. Secure thoroughly with duct tape, trying to make it as airtight as possible.
2. Insert the PVC pipe or tube into the other end of the pool noodle. This is the launch position for your rocket.
3. Make your rocket by rolling an 8.5 by 11 piece of paper into a tube so that it fits around the outside of the launch tube. Don't make it tight; the paper should slide on and off. Tape it in place. This is the fuselage of your rocket.
4. Use clear tape to attach a ping pong ball to one end of the rocket's nose.
5. Cut some wings and rudders out of cardstock. Experiment with different shapes and sizes. Attach them to the fuselage with tape, and decorate if you'd like.
6. Load the rocket onto the tube. Place the two-liter bottle on the ground and aim the launcher. (It may be easier to ask a partner to hold the launcher for you.) Stomp on the bottle to watch the rocket fly! To launch again, just blow into the pool noodle until the bottle re-inflates.

What's happening?

When you stomp on the bottle you compress, or squish, the air inside. This compressed air has to go somewhere, so it escapes through the easiest way out—which is the other end of the launcher. By placing the rocket over the other opening, this escaping air pushes it out of the way. If the compressed air didn’t have an escape route, like the launching tube, the container would burst. That’s why compressed air or gas containers like pressure cookers and propane gas cylinders always have a safety valve that keeps the pressure from getting too high.

Tips

• If you don’t have a pool noodle, any tube you can make airtight will work, such as a bike inner tube or PVC pipe.
• The duct tape or bottle will eventually wear out from all the stomping. When that happens, just cut off the end of the pool noodle and attach a new bottle.

Recommended reading

Planes, Gliders and Paper Rockets: Simple Flying Things Anyone Can Make—Kites and Copters, Too! by Rick Schertle and James Floyd Kelly

Explore Flight! by Anita Yasuda, illustrated by Bryan Stone