Archive for March, 2015
It’s Spring Break and, as a result, time for a fun project. After Drew saw a video of a similar project on YouTube, we had to try it so today was our day to build a hovercraft! We’re not talking about a water-going, self-propelled vehicle here, though, but the first step in that direction in the form of a leaf-blower-powered platform that can be pushed around. Think hoverboard or something along the lines of a very large air-hockey puck.
The original project we saw on YouTube used a plastic coffee can lid in place of the jam jar lid we used in the instructions below. We started with the plastic lid but discovered that it wasn’t strong enough and ripped off within a few minutes of testing the hovercraft. The metal jam jar lid proved a much more robust alternative.
Without further ado, here are the instructions…
- 1 x 8’x4; sheet of 1/2″ plywood
- A roll of duct tape (of course!)
- A 6′ diameter circle of thick (6 or 7mil?) plastic sheet.
- 12 feet of plastic pipe insulation or pool noodles
- 1 x plastic garden chair
- 1 x leaf blower. Gas powered is better but electric would work too.
- 1 x metal jam jar lid
- 1 x 2 inch bolt with nut and washers
- 4 x 3/4″ screws (or any length suitable to join 2 1/2″ ply sheets without protruding)
- 4 x 1 1/2″ screws (or length suitable to attach chair to ply without protruding)
- Staple gun
- Router and/or sander if you have them, sandpaper and elbow-grease otherwise.
- Cut the 8’x4′ into two 4’x4′ pieces and stack them on top of each other to form a single 4’x4′, 1 inch thick platform.
- Drill a hole through the exact centre of the sheet and use the bolt to hold the pieces together temporarily.
- Use the 4 short screws to attach the sheets firmly together. Make sure that you choose screws which are long enough that the sheets are securely joined but do not protrude through the bottom since this could puncture the skirt plastic later.
- Attach a 4′ piece of string to the central bolt and tie a pencil to the end then run it around the sheet to draw a 4′ circle within the 4′ square.
- Use the jigsaw to cut out the circle.
- Round off the edges of the plywood to remove any sharp pieces. We used a router to round off the edges then a sander to finish the process. Make sure that you clean up both the top and bottom edges.
- Measure the diameter of the leaf blower output tube and cut a hole the same diameter about half way between the edge of the plywood and the center. The leaf blower tube should fit snugly but be able to be inserted and removed without too much difficulty. We’re not going to permanently attach the leaf blower so this fit is important (though, if you wanted to duct tape the blower to the platform, I’m sure that would work).
- Remove the bolt you used to hold the plywood sheets together in step 2. Don’t forget to do this! If you leave it in place, you’ll have to remove the plastic skirt to get it off later and that wouldn’t be good.
- Place the plywood over the top of the plastic sheet so that the centres line up. Be careful not to puncture the plastic!
- Fold the plastic up over the edge of the wood and attach with staples about 1 inch in from the circumference of the wood, pulling the plastic towards the center between each staple. We used 1 staple every couple of inches around the entire circumference.
- Trim the plastic sheet so that about 1 inch remains between the staple line and the center of the plywood. You should end up with about 2 inches of plastic visible around the whole edge of the plywood with a line of staples in the middle.
- Cut 6″ pieces of duct tape and use them to seal the plastic to the plywood. Go round the whole circle twice to make sure that all the staples are covered and that you have a good seal.
- Turn the whole assembly over and you should have a reasonably tight sheet if plastic covering the bottom of the plywood circle. It shouldn’t be too loose. Don’t worry about the skirt inflating – it should be fine.
- Cover the center area of the plastic sheet with a layer of duct tape. You will end up with a 1 foot square of tape centred over the bolt hole you drilled earlier.
- Drill a hole in the middle of the jam jar top and use the bolt with washers to attach this to the underside of the skirt. This holds the skirt up in the middle and allows it to form a ring when inflated.
- Cut 6 holes in the duct tape square around the jam jar lid. Each hole should be about 2 inches in diameter and about an inch or so from the jam jar lid. These are the vents through which air will pour to lift the hovercraft.
- Cut the pool noodles or pipe insulation along one long edge and slide the cut over the edge of the plywood to form a bumper around the hovercraft. It should cover the duct tape and edge of the skirt. Use staples to hold it in place on the top of the hovercraft. DO NOT staple it underneath.
- Depending upon the size of bumper, you may need to cut a piece off on the underside. You don’t want the bumper to be deeper than the inflated skirt. We had to cut about half of the bumper off after our first test because it was dragging on the ground when the skirt inflated. Here’s what the skirt looks like when it’s being inflated. Notice that the inflated skirt is lower than the bottom of the bumpers.
- Screw a plastic lawn chair to the top of the hovercraft taking care not to use screws that will protrude through the bottom of the plywood and puncture the plastic skirt.
- Fire up the leaf blower, stick it into the hole on the top of the hovercraft and start sliding around!