Air Powered Rockets

From SEDSWiki

In this demonstration, use a sequence of devices to show how you improve stability and performance.

Balloons

Start by asking the kids if theyve ever made a rocket, and show them that they have, whenever they blow up a balloon and let it go. Obviously it's unstable and going to go everywhere. I like to make a big show of aiming at one of the kids with the balloon. Ask for ideas about how you could make it go straight. If they don't think of fins, show them the second demonstration and ask about the difference.

Straw Rockets

To show how the fins make it go straight, build a couple of rockets by taping some fins and a nosecone to a straw, and fitting it over a smaller stirrer straw, and blowing into it. The furthest these will go is about 12 feet. If you're so inspired you can build bigger rockets with bigger straws and use something more than your own blowing. Discuss the purpose of the fins for stability and the nosecone to decrease drag and make sure the air goes out.

If this is a short presentation you may want to bring a few extra smaller straws to let the kids try it out. For a longer activity you may actually have the students build some.

Pump-air rockets

There are some commercial toys (for instance from Air-hogs) that run for ~$30 that are a good demonstration of improving the range and power by using more air, and using it at a higher pressure, so that you have more propellant moving faster. It also goes really fast and really high (150 feet) or hits the ceiling, and impresses the kids. Change the number of pumps to change the pressure and amount of air.

Discuss how this increases the height and whether or not this can be used to get to space. This is a good gateway to discuss chemical rockets. Obviously this part is rather expensive, and the first two can be very effective on their own.