Life Science Curriculum 8-12
Submitted by: Jordan Buzzell
Institution: Azusa Pacific University
Title of Experiment: Build Your Own Hovercraft
Tape (Just in case)
Scientific Background of Experiment:
British engineer Christopher Cockerell invented the hovercraft in 1955. A hovercraft exploits the power of compressed air to lift itself above the surface of the water or ground. Buoyed up on a cushion of air, it can the float and travel rapidly because there is little friction with the water or ground. The hovercraft uses propellers for horizontal movement and rudders for steering. These may operate in the air, as in an aircraft, or underwater like those in a ship.
This project is designed to teach the concept of friction and everything that relates to it. Friction is caused when two objects rub against each other resulting in a resistance against each other. Friction has also been described as "the force that opposes the movement of objects sliding over each other." Friction occurs because no surface is perfectly smooth, however flat it may appear. All surfaces consist of tiny "hills and valleys" and where the microscopic peaks on the two surfaces come in contact they weld together, making it hard for one surface to slide over another. The heavier an object is, the more peaks that come in contact with the other surface, and thus create more welds which is why heavier objects are harder to slide.
When Christopher Cockerell invented the hovercraft in 1955 it started as a pair of tin cans linked up to a vacuum cleaner. Now you have a chance to recreate history and build your own hovercraft. By building your own hovercraft, you will be able to see, firsthand, how friction can be overcome. The balloon acts as the compressed air, and when released, the friction between the cardboard and the surface it sits on is basically eliminated by lifting the microscopic peaks off of the surface and therefore, breaking the "welds" that have formed.
1) Cut a 4 inch square piece of cardboard
2) Punch a hole in the center of the cardboard square about the same size as the hole in the thread spool.
3) Glue the spool to the cardboard being sure that the holes line up. It is very important that no air escape where the spool is glued to the cardboard.
4) Cover the top of the spool with paper and glue it to the top. After it drys, punch a hole in the newly applied paper, again lining it up with the spool.
5) Blow up the balloon and twist the end so that air won't escape. Stretch the balloon over the top of the spool.
6) Put your hovercraft on a flat surface and let go of the balloon.
Misc. Helpful Information/ Hints/ Suggestions:
The instructions call for cardboard, but even poster board will work. While I was performing this experiment, normal cardboard appeared almost too heavy. The piece of cardboard must also be level and not warped. If it is warped, then the compressed air will not support the hovercraft.
As was stated before, it is extremely important that no air escapes where the spool attaches to the cardboard. If air continues to escape, tape does a good job of preventing any leaking of air. Try very durable glue and go from there.
A fully inflated balloon weighs down your hovercraft. You will find that once the balloon is able to stand up straight, the hovercraft will be more mobile.