The ribs have been built and are temporarily attached to a jig. They were cut from 1X6, #2 FPS (Fir, Pine, Spruce...I knew those forestry classes would come in handy someday). The jig is made of 2 20' 2X4's and is used to keep the ribs spaced out correctly, and to keep the whole thing level. Along with the plans, I also bought a full rib outline which I highly recommend. After I cut the wood for the ribs, I laid a clear drop cloth over the outline and did all of my gluing on it to assure proper fit.
The stringers are now attached. You can see how they fit together at the nose. A triangle block of wood is used to glue and screw the stringers to. The block is not in the plans, so if you're planning on building a similar hovercraft, I highly recommend using one. It helped out tremendously in forming the point. Although this pic makes the nose appear off center, it really isn't. The support on the rib is off center, not the nose.
I've begun to skin the bottom of the craft. I epoxied all of the contact surfaces and used galvanized brad nails to hold the skin tight to the ribs while the epoxy cured
Another pic of the nose skinned. I'm using 1/8" marine grade Mahogany luann that has been imported from France. I've worked with a lot of wood in the past, but this stuff takes the cake. It has incredible strength and is wonderful to work with. Granted, as everything else, quality comes at a price. I need approximately 9 sheets, and at $31-38 a sheet, it's just about enough to break the bank, but it's well worth it.
Here, the flat bottom of the craft has been skinned. All joints will be taped with fiberglass on the exterior, and plywood splices will be used in the interior. That's Walt with the camera in the background.
Okay, time laps here. This was taken July of '99. After a not so harsh, abnormal Minnesota winter, and many feuds with the 'rents about garage space, I'm back to working on the hovercraft. The sides have been skinned with 1/8" luann. Next comes the slightly harder task of skinning the angled bottom where the skirt will be attached. I have since added a new tool to my arsenal. Installing the skin with a pneumatic brad nailer has increased speed greatly. Pounding nails through the skin into the stringers is like nailing into a springboard. I highly recommend the use of either a pneumatic nailer or stapler. Screws work as well, but may require wood filler.
I've installed a skin support for the nose section. It's nailed and
epoxied in between the two main stringers and to the nose block.
Again, the support isn't in the plans, but I feel it's necessary for strength.
The last thing I need is to have the nose cave in.
With the exception of the nose, the entire bottom has been skinned. The angled bottom area is where the bag skirt will be attached. 1/4" ply is used here because the skirt tack strips will be glued directly to the skin. The extra thickness is required for strength so the skirt doesn't pull the tack strips and skin right off.
A closer shot. Incidentally, the joint where the nose skin and the skin that's already on the hovercraft does not meet at the rib. To strengthen the joint, I glued and nailed a block of wood from the inside to connect the two pieces of skin
The nose has been skinned now. They're kind of hard to see, but notice to blocks of wood behind the rib used to splice the skin seam together as mentioned above. The seam going down the center of the nose was filled with thickened epoxy. Epoxy alone is much too thin and would have just flowed right through the seam, so I added saw dust from the belt sander which thickened it up nicely. It also gave it a wood appearance. Imagine that! West Systems Micro Balloons or Fiber would have worked as well, but I happened to have an abundance of saw dust, which is free.
I grew tired of needing 2 people pick up the frame, move it to the center of the garage, while a third person put benches under it, so I built stands with casters. This puppy moves with just the touch of a finger. I have to give old college roommate credit for the wheels. He works at NH Northern in Forest Lake, and without his help (discount), I wouldn't have those nice wheels. Thanks Shawn!
It's really starting to look like something now. Notice the top stringers, how they continue past the last support. These will be used to form the engine enclosure later on.
My brother and his wife moved into their first home. While that's great for them, the house came with this huge garage. There's enough room for 2 cars, the hovercraft, all the tools and toys you'd ever need, and an elephant if you had such a need. Since space at my 'rents house was tight, My brother offered to store the craft in his massive new (heated) garage. (Secretly, I think he just wanted the bragging rights of having a hovercraft in his garage. I know I would!) Thanks Mark!
These are my two favorite shots of the hovercraft so far. Just picturing it flying off of the trailer in the parking lot, down to the boat launch, and into the water helps keep the enthusiasm up. A note about the stand. It was bumped off center, not the hovercraft. I must have bumped it sometime before taking this shot. The hovercraft is living in South St. Paul and I'm going to school about 250 miles north from there. I didn't notice this until I was back up at school. I was really concerned that being off center would depress the skin more on one side, but nope, not a problem.
A shot from the inside pointing forward. The hovercraft spent almost a full year out in my back yard under what I thought was a good enclosure. As you can see, it sustained minimal water damage, nothing major. I've since sanded off the water damage, now it's as good as new. The quarter round on the left will be epoxied into the drain track as a support for the landing skids. Because the landing skids are wider then the main stringers, which they're glued over, the quarter round is used to support the skin because there is quite a bit of overhang onto the unsupported skin. I'll get a pic of that next time I go home.
Here are the landing skids. They're 10 ft long running from the 7th rib, forward. I epoxied and nailed them into place. The front end of the skids are angled so they won't catch on anything while hovering or landing. Steel strips will eventually be attached to the skids for wear protection.
Here's the bottom right rear corner. You can see where the tack strips are attached. The strips are what the skirt is attached to.
A closer look.
Here, my father and I are flipping over the hovercraft. It's still light enough for two people to pick up and flip.