A Real Gem
Vehicles that skim over rough seas and rugged terrain on a cushion of air are called hovercraft, hydroskimmers or ground-effects machines (GEM). You can build a model that will show how these almost friction-free air supported vehicles work.
Materials:
- A metal pie pan with a smooth bottom
- A spool
- Glue
- A balloon
- Turn the pan over and punch a small hole in the center.
- Glue the spool to the inside of the pan, centering it over the hole.
- Stretch the neck of the balloon well down over the spool.
- Inflate the balloon by blowing through the hole in the bottom of the pan.
![A balloon with a spool on the end resting in a metal Pie pan.](https://webarchive.library.unt.edu/eot2008/20081019214256im_/http://www.faa.gov/education_research/education/student_resources/kids_corner/ages_10_12/real_gem/images/image1.gif)