One day while at Lowes I spotted some 7/16th roofing OSB that was on sale for nine dollars. I just couldn’t resist and ended up buying a piece. For deep within the recesses of my mind the dreams of sliding about on a personal hovercraft started to bubble forth into my consciousness. A small voice whispered to me, “It is time”, and before I knew what was going on, I was strapping a 4x8 piece of OSB to the top of my vehicle.
Step 1: Setting the Stage for Success, Let's Draw a Circle!
Because, and I must stress again that, I am lazy. I was all ready to engage my saber saw into cutting out this crudely drawn pattern on the OSB, when I started to feel a little pang of shame growing inside of me. Sure this is a crappy ghetto version of a hovercraft but I should at least have an ounce of self respect in making it appear as if some symmetry was involved with its construction. It then became clear to me that I needed a better way to draw a circle on to the OSB.
Step 2: Drawing a Circle Part Deux
Next I drilled two ½ inch holes in a scrap piece of wood. The distance apart being the radius of the circle, this was around 2 feet. I then secured one side of the scrap wood to the center hole of the OSB and dropped a purple crayon into the other hole.
I have to say that I was pleased with the results. I was left with a big fat purple line that my saber saw could easily follow. Unfortunately, by the time I had figured all of this out it was starting to get late so I decided to save the cutting for another day.
Step 3: Time to Start Cutting
Additionally, I notched out the vent hole, where the air will enter the skirt. According to Beaty’s Ultra-Simple Hovercraft design, the vent hole is placed halfway between the center and the edge of the disc. I obliged him on this. While I was cutting this hole I started to think about the center hole. Beaty uses a bolt to hold the center of the skirt up close to the disc to create a doughnut shape. I wondered if, instead of using a bolt and nut, I instead used a small pipe and then screw a pressure gauge onto the pipe. This way I could get a pressure reading of the air under the skirt.
Step 4: Mounts
Step 5: Finshing the Mounts
If I wanted the vent pipe to be secure against the disc I would need it to protrude at least a little from the bottom. To minimize this distance I used a PVC coupling that I cut down with the miter saw.
Once the vent pipe was installed I used a sort of woodworkers putty/glue to secure it into the hole.
Step 6: Considering the Skirt
Next I drilled a hole though an old lid from a drywall Spackle bucket to act as the center support for the skirt. for measuring purposed a bolt was screwed into it and the center hole of the disc. Later, I plan to fasten it to the disc with a small pipe that will allow me to take pressure readings. Some may be puzzled as to what the lid is used for. This will act like a big washer holding the center of the skirt against the disc and allowing the air filled skirt to maintain a doughnut shape. The skirt will have strategically placed holes in it to allow air out to form a cushion of air. For now I am using this dirty lid to measure how far away from the center I will place the standoffs.
Step 7: The Standoffs
These things are cheap and have all the properties to fit my needs. I think I spent $1.99 on one at Target. What else can you buy for $1.99? I just needed to run some tests on how I could secure pieces of this to the bottom of the disc. I figured I can slice it down like a meatloaf into 2 inch thick pieces and then line the outer perimeter of the disc with them. I took a small slice and used epoxy to affix it to a scrap piece of OSB. I then placed a weight on top of it and let it sit overnight. The result was perfect. No matter how hard I tried I could not pull the noodle off of the OSB. I just need to slice the noodle down and get to gluing.
Step 8: Drawing More Circles
Next I roughly placed the standoffs along the yellow line.
Step 9: Glue and Wait
Twenty four hours later and everything appeared to be glued nicely. I was not able to remove any of the standoffs no matter how hard I twisted and turned them. I must admit that the picture made me think that I was assembling a gigantic escarpment wheel. Hmm, a neat idea for a future project?
Step 10: The Skirt
The main issue I had to tackle was how to get a hole in the plastic that would be strong enough that it would not rip the plastic when tugged around by the forces of movement and inflation. I tried two things. I cut the plastic with a razor and I also melted a hole with a soldering iron. The melting seemed to produce a better more durable hole in the plastic so I settled with that. I further reinforced the hole with a piece of Gorilla Tape on each side of the hole. Below is a picture of my test piece. I pulled and tugged and attempted to rip the hole and was not able to. So I think I have my method.
Finally, I laid out my 6x8 tarp and placed the disc on top of it. I then marked where my cuts and holes would go.
Step 11: More on the Skirt
Next I needed to secure the skirt to the center of the disc to insure a doughnut like shape. I used the top of an old Spackling container as a sort of giant washer to take some of the wear off of the skirt when inflated. Also, I was able to find a small ½ inch threaded pipe to secure it all together while allowing for pressure measurements top side.
Step 12: Up on the Top Side
Next I had to tape and staple the skirt around the edges of the disc. I first pulled the skirt taunt and then placed a small piece of Gorilla Tape on the tarp to hold it to the wood. I then stapled through this to hold things permanently. I made sure that every staple went through both tape and tarp. There had to be a layer of Gorilla Tape on top first to insure nothing would rip. The end result was like a billion staples and about a quarter of a big roll of Gorilla Tape. Yeah I know it looks trashy, but what the hell, it was holding :P
Step 13: Mounting Everything
Step 14: The Test Flight
Complete details of construction at Zero Sum Hacking
The attached video pretty much shows the life cycle of the construction, a brief test flight and some analysis at the end. Enjoy!