CD Hovercraft

Challenge

Can you make a CD hover?

Supplies

• • CD

  • Balloon

  • Drink bottle cap

  • Glue

What to do

• 1. Glue the drink bottle cap to the center of the CD

  2. Wrap the opening of the balloon over the top of the bottle cap

  3. Blow through the CD to inflate the balloon

  4. Set it down on a table and watch it hover

Inquiry Questions

• • Why does it hover but not fly?

  • Do some surfaces allow it to hover better than others?

  • What happens if you release it on a ramp?

What’s happening?

When the balloon deflates, the air is pushed under the hovercraft. This creates a small pocket of higher pressure air between the CD and the table. The difference in pressure above and below the CD is enough to lift the CD off the table. However, if the CD is too far away from the surface, the air pressures quickly equalize which prevent the hovercraft from flying. The smoother the surface, the easier it is to trap air underneath and the better the CD hovers.