the little book of experiments...
build your own hovercraft
Model Universe / Feel the Force
Air cushion technology
Age range 7-14
you will need
A balloon - not blown up (yet)
An old CD (e.g. free junk mail ones)
A cotton reel
Blu-tack
instructions
Stretch the neck of the balloon over one end of the cotton reel. You should be able to blow up the balloon through the hole in the centre of the cotton reel. But don't do that yet!
Blow up the balloon through the hole in the CD and through the cotton reel. Try not to let the air escape through the side of your mouth. It's difficult to inflate the balloon as you get a faceful of CD, but it's quite funny to watch others try!
Hold the neck of the balloon above the cotton reel to stop the air escaping. Place the CD on a smooth flat surface like a table top, let go of the balloon and give it a gentle push and off it goes.
further information
The air coming out of the balloon forms a layer between the CD and the table, so it can move around with far less friction to slow it down.
A hovercraft moves around on a cushion of air. Real hovercrafts have an engine and one or more fans to create the air cushion and also to provide thrust. The balloon in your model represents the engine and the fans. Real hovercrafts also have a ‘skirt’ around the perimeter of the craft, to contain the air cushion and to help them move over obstacles.
more ideas
Try making a hovercraft with a skirt. You could use one of the circular boxes that hold portions of processed cheese. Or try the polystyrene trays that some food is sold in – clean them out and turn them upside down.
If you just want to add a skirt to your CD hovercraft you could cut one out of a plastic bag and stick it on with tape.
Does the skirt make any difference to how long the craft stays above the table?
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