Hovercraft Basics

It's really amazing how simple a hovercraft is. In fact, you might have all of the components for building a simple hovercraft in your house right now. Whatever components that you don't have can be purchased at a local hardware store. Here's a list of everything you need to put together a homemade hovercraft:

• Leaf blower or vacuum cleaner that can reverse its air flow
• Large piece of plywood
• Large piece of plastic
• Small section of PVC piping
• Contact cement
• Staple gun
• Electric drill
• Skill saw
• Plastic can lid
• 1-inch bolt and nut

This Web site walks you through all of the steps of building a simple hovercraft. Children should ask for their parent's permission before attempting to build a hovercraft on their own.

When you've finished your hovercraft, you should have a vehicle that has a piece of plywood skirted with a piece of plastic and a vacuum cleaner or leaf blower sticking through a hole in the plywood so it can blow air underneath the craft. When you turn the motor on, the plastic skirt will fill up with air and the hovercraft will rise off the ground. Depending on how airtight it is and how much air is discharged into the skirted chamber, it will rise several inches to a couple of feet above the ground. It's really pretty cool, if it's done right.

Commercial hovercraft operate just like your homemade hovercraft. They usually have an oval or rectangular platform, a motorized fan and a large skirt material to trap the air underneath the vehicle. This air cushion underneath the hovercraft is called the plenum chamber. This plenum chamber is formed by the bottom of the craft and the skirt material. The air flowing into the plenum chamber will form a ring of air circulating around the base of the skirt to insulate the air cushion from the lower pressure air outside the skirt. This ring of air keeps the air under the craft from escaping.

Most large hovercraft have a large propeller attached to the back of it to propel it forward. Rudders attached to the propeller's housing allow drivers to steer the vehicle. On some smaller hovercraft, steering is performed by the driver leaning left or right. Steering a hovercraft is a little tricky: There's no contact with the ground, so steering the craft will feel slippery. In order to stop the vehicle, you just have to slow down the engine and the craft comes to a rest on the ground. One problem with driving a hovercraft is that the faster you go, the harder it is to maintain the cushion of air underneath the craft.