Extreme Science: Inertia Sticks

Make a CD hovercraft

What you will need:

  • Old unwanted CD
  • Empty 1 liter pop bottle
  • Scissors
  • Drill
  • 1/8” drill bit
  • Hot glue gun
  • Balloon
  • Razor knife or scraper
  • Adult supervision


1) Check your CD to make sure that the bottom is completely flat. Some CD’s have a very small raised rim near the center that can cause your CD hovercraft not to work as well and should be carefully removed by an adult using a scraper.

2) With the cap secured on the 1 liter pop bottle, carefully drill a 1/8” hole in the center of the cap.

3) Remove the cap and attach it in the center of your cd (on the top side) using your hot glue gun. Make sure that there is no excess glue extending down through the center of the CD or covering the hole that you drilled earlier.

4) Carefully cut the top of the one liter bottle off of your pop bottle. This cut should be just where the bottle begins to flare out. The very top part with the threads is the part that you want to keep.

5) Stretch your balloon over this top of the bottle that you just removed. The balloon should be stretched over the cut end, leaving the threads exposed.

6) Place your mouth over the threaded end of the bottle top to blow up your balloon. Once you have blown up your balloon, pinch the balloon to keep the air in while you thread the bottle top onto the cap that is glued to your CD. Place the CD hovercraft on a flat smooth surface and watch as it effortlessly floats across the surface.

What is going on?

Air molecules take up space. As the air rushes out of the small 1/8” hole that you drilled in the cap, it lifts the CD up in order for the air to escape. Since the force of the air escaping the balloon is greater than the gravitational pull on the CD hovercraft, the CD is lifted just enough to where it is actually riding on a cushion of air molecules.

Try this:

You can use this CD hovercraft to play games at your dining room table similar to air hockey. Get creative and make up a fun filled game with wacky rules!

Try the CD hovercraft on various surfaces. Are there certain surfaces that work better than others? Are there surfaces where the CD hovercraft does not work? Why?

Radical Rick

Extreme Science