Balloon Hovercraft

I teach a science workshop with Scientists in School called, "Air and Flight." As part of my introduction, I demonstrate Newton's 3rd Law by pushing my Balloon Hovercraft across the students' desks, much to their delight.

Yesterday, I was at the Malvern Town Plaza in Scarborough teaching children who passed by my table how to build balsawood gliders and hovercrafts.

Using the materials listed, make a hovercraft and try to make it travel as far as possible.

Materials:
1 old CD
1 wooden spool (or plastic..the type that once had thread on it)
1 12" party balloon
20 cm x 2 cm piece of duct tape
Thin card (if needed)

Construction:
1. Tear the duct tape into 4 pieces about the same length.
2. Take 1 piece of tape and attach half of it lengthwise to the base of the spool.
3. Centre the spool over the hole of the CD and tape the spool to the CD.
4. Inflate the balloon to stretch it somewhat. Let the air out. Attach it over the wooden spool.

Testing:
1. Inflate the balloon by blowing through the hole at the base of the CD.
2. Gently push the hovercraft along a smooth surface.

How far did it go in cm (m)?

Extension:
1. How can you make the balloon cover a greater distance? (Possible Answers: Use larger balloons, use smoother surfaces, cut a straw the length of the spool and put it inside to make the hole narrower and possibly increase the thrust).
2. How can you prevent the balloon from dragging behind once its air is expended? (Possible Answer: Place a thin card around the neck of the balloon to prevent it from dragging).