Building and testing a tabletop hovercraft has been a big hit at our STEM events. You can easily build and test one at home to see and learn about how cushions of air enable things to float and hover.
- A CD or DVD (old, used ones are fine for this activity – this is a great way to re-purpose those music and movie discs you don’t want anymore)
- A 9” balloon (having multiple balloons is handy since they occasionally pop)
- A pop-top cap from a liquid soap bottle or a disposable water bottle
- A hot glue gun
Building the hovercraft is pretty simple – hot glue the pop-top cap over the middle of the CD. It is important that the hot glue makes a complete circular seal around the cap – you don’t want any air to escape between the cap and the CD when you’re using the hovercraft later. Then give the glue a few minutes to set.
Here are the basic steps to use your hovercraft:
- Make sure the pop-top cap is in the closed position
- Blow up a balloon and hold the balloon closed so air can’t escape
- Place the balloon onto the pop-top cap
- Place the hovercraft on a smooth surface (like a table or counter top)
- Pull up the pop-top cap so that air can escape
- Give the hovercraft a gentle nudge so it can float across the surface
The airflow going out the bottom of the CD created by the balloon creates a cushion of air between the CD and the surface. This lifts the CD up and reduces friction, enabling it to hover and move. For comparison, you can hypothesize and test what will happen if you:
- Give the hovercraft a nudge without an inflated balloon
- Only open the pop-top cap halfway
- Use a larger and/or smaller balloon
- Use a non-smooth surface like a rug
- Place small weights like pennies or paper clips on the hovercraft
Hoverboards, air hockey pucks, and even Elon Musk’s proposed Hyperloop system use thin cushions of air to move more easily. Let us know how your hovercraft works and if you find anything else that uses these same principles!