How to build a hovercraft out of “found” materials that could be used to transport a heavy backpack full of school books.
BackPack On A Leash
How it works:
We are using a gas leaf blower to power our hovercraft. The blower forces air at the approximate rate of 150 cubic feet per minute into the skirting on the bottom of the craft.
The skirt inflates around a 10 inch plastic disc forming a “doughnut hole” in the center of the skirt. We cut 6 holes in the skirt around the disc to let the air out and direct it toward the center of the craft.
This forces the air under the craft creating an “air bearing”, or a thin layer of air under the skirting. The hovercraft then floats on this thin layer of air making it possible to transport our backpack with a full load of books. We tested the maximum weight it would carry and still float at 110 pounds.
To move our hovercraft we either have to push it in the direction we want it to travel, or we attached a piece of rope which we used like a leash to tow it around.
Materials and tools used:
- Sheet of ½” 4’ X 8’ plywood
- Piece of 4 mil. plastic sheeting
- Lid from a 5 gallon bucket
- Lid from a 2 gallon bucket
- Duct Tape
- 4X4 post bracket
- 4X4 post
- Screws, nuts and bolts
- Piece of 4” drain pipe
- Old piece of garden hose
- Small bungee cord
- Staple gun
- Utility knife
- Short piece of garage door weather stripping
- Scroll saw
How to build the hovercraft:
- Create a compass to draw out a 4’ circle on the sheet of plywood. We used a pencil attached to a string and a nail. Center the nail on the plywood, 2’ from the end and 2’ from the edges. Pull the string tight and use the pencil at 2’ to draw a 4’ circle.
- Use the scroll saw to cut the circle of plywood so you have a 48” round piece that will become the deck of the hovercraft.
- Cut a hole in the plywood to exactly fit the end of your leaf blower tube. Put the hole half way between the edge of the deck and the center.
- Take the lid from the 5 gallon bucket and cut a hole in it to match the blower tube and the hole you cut in the deck. Screw the lid to the deck so the holes match up.
- Cut the 4” drain pipe to approximately 18” or enough that it will secure your blower tube standing up. Duct tape the pipe to the lid making sure it is lined up over the holes.
- Next to the lid, bolt a 4X4 post bracket to the base. Make sure the bolts don’t stick too far off the bottom of the deck as this will damage your plastic skirting.
- Stand your blower in the tube to get a measurement for the support post. Cut a 4X4 post to this measurement and bolt it in the bracket. Cut a second block of wood to fill the gap between your blower and the stand post.
- Drill a hole in the center of the deck to fit the bolt for the doughnut hole.
- Cut a 10” circle or disc from the 2 gallon bucket lid. Smooth the edges so the disc doesn’t cut your plastic sheeting. Drill a hole in the center of the disc for the mounting bolt.
- Cover the bottom of the deck with 4 mil. plastic sheeting. Leave enough to wrap over the edges on top. Put the 10” disc in the center and bolt it onto the deck over the plastic sheet. Make sure your bolt doesn’t stick too far out on the bottom.
- Pull the plastic so it is fairly tight, but not too tight. You must leave enough room for the skirt to inflate at least two inches. Staple the sheeting around the top of edge of the deck at least every 4”. Trim the extra plastic off with a utility knife. Duct tape the edge of the plastic sheet to create a seal that will keep the air below the deck.
- On the bottom side, cut 1” holes in the plastic sheeting, around the center disc – need 6 holes evenly spaced.
- Cut the old garden hose up the center, wrap it around the edge of the plastic covered deck, and staple to secure it. This gives you a bumper to protect the plastic sheeting from being torn. We also found the hovercraft operated better with the bumper on than with the bumper off.
- Mount your blower in the stand. Make sure the tube is place tightly in the holes you cut through the deck. Use a short bungee cord to hold the blower against the stand.
- Stuff the garage door seal around the top of the drain pipe to seal the tube and make sure all the air is directed into the skirt.
- Start up the blower to operate your hovercraft. You may have to lift the deck up a bit to allow the skirt to inflate. Make sure your backpack or payload is placed on the deck to balance the weight to the center as best as possible.
You now have a working hovercraft!