Safety is the Number 1 priority!
Be sure to read and follow the safety requirements and recommendations for the tools you are using and those stated by the adult you are working with. Always wear eye protection when building your hovercraft. Always wear ear protection when operating loud items such as saws. Always wear dust masks when you are working with tools that generate dust. Gloves should be worn when working with rough wood to help avoid splinters.
| ||CAUTION! READ and FOLLOW the manual for your saber saw, including all safety notices. NEVER place your hand or fingers under the board you are cutting. The saw blade will be exposed on the underside of the plywood. |
|Mark and cut out the plywood disc. A disc of at least 102 centimeters (40 inches) in diameter is recommended. You want a large surface area disc to lift the weight, and you also want your hovercraft to have a wide base so it is stable. Sand the edges to get rid of and roughness and splinters. Pick one side to be the top and one to be the bottom. |
|Mark a hole on the plywood large enough for the blower exhaust. This should not be in the center of the disc as you are going to cover the center later with the coffee can lid. It should be offset to one side. Also consider how your blower and chair will sit on the disc later and make sure the blower and chair will work without interference. Cut the hole. (Picture 2)|
| ||CAUTION! When using a utility knife, always be sure the sharp edge is pointed away from anyone nearby, including the person doing the cutting. |
|Measure and cut a circle from the plastic sheet. You need enough to cover the underside of the disc -- with some slack -- and then enough extra to wrap around over edge to the top of the disc where you will staple it near the perimeter. We recommend you make the plastic circle at least 15 centimeters (6 inches) in radius (30 centimeters, or 12 inches in diameter) larger than the plywood disc. You can always cut off extra later. You will be forming a bag out of the plastic and the plywood disc and so you will not be pulling the plastic taut over the plywood. The bag will fill up with air that will travel out a number of small holes you will cut in a later step. It is this air that will lift the hovercraft off the ground. |
| ||Turn the disc over so the bottom is facing up. Place the circular plastic sheet over the plywood disc lining up the centers. Place the lid -- a coffee can or whipped topping lid -- over the center of both. With a permanent marker, trace a circle around the lid onto the plastic sheet. Draw a second concentric circle on the plastic sheet about 7.5 centimeters (3 inches) smaller in radius than the outer edge of the plywood disc. These circles can be quickly hand-drawn. They are only to show you approximately where to punch the small holes in the plastic.
Remove the plastic lid.
| ||Using a single-hole office paper hole punch, a utility knife, or hole punch for leather, punch or cut a number of small holes relatively evenly spaced over the surface of the plastic sheet in the area between the two circles. You are creating the exit holes for the air to leave the hovercraft to lift you off the ground. If you use an office hole punch, you can do this by creating small folds in the plastic just where you want to punch, pushing the fold ½ way or less into the punch, and then punching the hole. If the office hole punch method doesn't work, a utility knife or a leather punch and hammer can be used.
This may require some trial and error. In our unit, we used about 100 holes about the size of those in a looseleaf piece of paper. The number and size you need may vary. If you don't cut enough holes, you can add some even after you've attached the plastic sheet to the plywood disc. You may also find that you need some additional holes closer to the edge of the plywood than the circle you drew in step 4. You can add more at any time. When someone is riding the hovercraft you don't want to see these small holes around the perimeter. If you can see them, then they are just wasting air by blowing it out to the side instead of using that air pressure to lift the hovercraft.
If you use a utility knife, you should be careful not to scratch the table or floor you are working on. It is best to put a protective surface underneath. One suggestion is to cut the holes directly on the plywood disc. While the plywood needs to be smooth in general, you don't need to worry about light scratches in the surface of the plywood from the knife.
|CAUTION! Most leaf blowers have a long nozzle that you may need to remove to fit the blower onto your hovercraft. When working with the blower with the nozzle removed, MAKE SURE the blower is UNPLUGGED from the power source. If you do remove the nozzle from the blower, be sure the blower mount or other part of your design fully covers any exposed portion of the fan or impeller.|
|Design and build a mount for your blower. Attach the mount to the top of the plywood disc. You can also do this step at other times, but this order allows you to use flat head screws from the bottom side of the disc to attach the blower mount (before you attach the plastic sheet).
Depending on your design, you can either attach the blower to the mount and plywood disc now, or do that later. Use duct tape to seal any gap between the blower outlet and the plywood disk or blower mount. If you can design a mount that lets you attach the mount now, and the blower later, it will make some of the remaining steps easier.
|CAUTION! READ and FOLLOW the manual for your staple gun, including all safety notices. NEVER point the stable gun at anyone. Only use it when it is placed firmly up against the surface you are applying staples to.|
|Place the plastic sheet on the floor or table, and place the plywood disc on top with the top of the plywood facing up and the centers aligned. Wrap the plastic around the plywood disc and staple to the top of the plywood at the perimeter. Leave some slack. We recommend 1.2 to 2.5 centimeters (1/2 to 1 inch) of extra plastic sheet along the radius all the way around the plywood disc as the plastic lays flat under the plywood. This too may require some trial and error. Place duct tape over the staples and edges of the plastic to seal this edge.|
|CAUTION! If the tips of your screws come through the top side of the plywood disc, cover the point with something to avoid injury. Silicone caulk or silicone glue can be used to make a rubbery protective cap.|
|Attach the coffee can lid to the center bottom of the disc with flathead wood screws. Use at least 10 screws evenly spaced near the perimeter of the lid. This keeps the hovercraft more evenly balanced by making the plastic bag into the shape of a donut when it inflates. We recommend you consider using a thin washer with each flathead screw to reinforce the attachment. The screw heads will stick out a bit further, but should still not interfere with the operation of your hovercraft.|
|Attach a rope to a point on the top of the disc or the blower mount. This will be used by the operator to pull the rider along on the floor.|
|Attach the chair so that the rider's weight will be approximately located over the center of the disc. Remember that the rider and chair are probably going to be heavier than the blower, and you are trying to place the center of all the mass over the center of the hovercraft disc.|
|CAUTION! Be sure the emergency stop switch and the power switch on the blower are both in the "OFF" position prior to connecting either to the power source.|
|Attach the emergency stop switch to the chair where the rider will easily reach the switch. This will let the rider stop the hovercraft any time. Connect the extension cord and blower to the emergency stop switch. If you are using a power outlet strip as shown in the photos, connect the blower motor cord to one of the outlets in the strip, and the plug from the power strip to the extension cord. Use electrical tape to cover unused outlets in the power strip and tape, clips or tie-wraps to secure the cords to the hovercraft.|
|Anchor the extension cord to the hovercraft near the attachment point for the rope, using clips or tie wraps. |
|Lay the rope and the cord out on the ground along side each other. Pull the rope taut, and tape the extension cord to the rope every 45 centimeters (2 feet), leaving some slack in the extension cord. This will allow you to move the hovercraft by pulling on the rope and not straining the extension cord. The operator will stand about 1.2 to 3 meters (4 to 10 feet) away from the hovercraft and pull on the rope to move the hovercraft.|
|14|| ||Clear an open, dry, flat space. A garage floor works well.|
|15||Test your hovercraft with no one riding it. See that it lifts off the floor and floats about as the operator pushes on it or pulls on the rope. Test the emergency stop switch to turn the hovercraft off.|
CAUTION! Never suddenly stop, start or redirect the motion of the hovercraft as it glides across the floor. Always move the hovercraft slowly across the floor and gently stop, start or redirect it.
Never ride or test the hovercraft in a wet or damp area. Be sure the entire length of the electrical power cord, from the hovercraft to the power outlet, is also in a completely dry area as well.
Always have an adult present when operating the hovercraft.
The rider should ALWAYS be sitting in the chair during the hovercraft operations.
|If it looks like it's working fine, turn the hovercraft off and have the first rider get onboard. Only one rider should ride the hovercraft at once. The adult operator should turn on the blower and the give the hovercraft a slight push. The rider should see if the craft is balanced -- or which way the chair should be moved to balance it.|
|17|| ||If the hovercraft seems unbalanced, stop the power and get off the hovercraft. Move and re-attach the chair, and try again.|