Making a hovercraft

Thursday, January 7th, 2010
We were talking about hovercrafts today, about how they move by floating over the water or over land, on a layer of air. We thought it would be very interesting to make a hovercraft.
We needed only 4 things to make our hovercraft - a top from a drinks bottle, blue tack (or play dough or sticky tape), an old CD or DVD and a balloon. First of all we stuck the bottle top to the CD with blue tack. We were careful to make a good seal between the bottle top and the CD. Next we blew up the balloon, and put a twist in the neck of the balloon to make sure that the air didn't escape from the balloon as we were stretching it over the bottle top. When the balloon was untwisted, the air from the balloon went through the bottle cap, and through the hole in the CD, and under the CD. This caused the CD to sit on a layer of air (caught between the CD and the floor). The whole hovercraft slid nicely across the floor. We wondered if we could make a hovercraft with other materials rather than the CD, so we tried a cardboard hovercraft, a plastic cup hovercraft and a hovercraft made from tin foil. We thought they might travel better because the materials we were using were lighter than the CD.

This is what we discovered:

The hovercraft made from cardboard didn't move at all. The air was escaping from the balloon but the cardboard was probably too soft to let the hovercraft move. The hovercraft made from the plastic cup did work, but not as well as the CD hovercraft. And finally - the tinfoil hovercraft didn't move at all, probably because the tinfoil was very soft which meant that the air could easily escape from under it, without making the hovercraft float on the air at all.

It is really interesting thinking up different ways of getting things to move. We always guess what is going to happen before we try our investigations out. We are using all our scientific skills each time we try a new investigation.