 | This is the hotwire bow I used to cut the styrofoam. It is made from scraps of 1x2 and nichrome wire from an old hairdryer. The wire is about 8 inches long. | ||
 | This is a jig I made to make straight cuts with the hotwire bow. It is somewhat analogous to a table saw in that there is a rail that keeps the styrofoam aligned correctly while it is fed through the hotwire bow.. | ||
 | This is a jig I made to make radial cuts with the hotwire bow. I used this to cut the styrofoam for the thrust duct. These jigs took much longer to design and build than I anticipated, but there was simply no other way to get the quality cuts that I wanted. | ||
 | I cut the thrust duct using the radial jig. | ||
 | This is another jig I constructed to cut the rudders. I traced the airfoil shape onto pieces of 1/8 inch plywood and then used the wood as guides for the hotwire. | ||
 | I sanded the thrust duct to give it the profile of an airfoil. | ||
 | Here you can clearly see the airfoil cross section of the thrust duct You can't see it here but the underside has a light coat of fiberglass (using 0.56oz glass cloth. | ||
 | I cut slots into the inner surface of the thrust duct to make the styrofoam flexible enough to bend into a 7.5 inch radius duct. Here you can see how well the styrofoam bends when notches have been cut into the inner surface. | ||
 | I wrapped a sheet of 1/64 inch plywood around the 1/4 inch plywood circle and then applied epoxy to the outside surface of the 1/64 inch plywood and bent the styrofoam into place. | ||
 | I secured the foam around the plywood circle with twine while the epoxy cured. | ||
 | I applied three layers of fiberglass using 0.75 oz glass cloth to the outside of the thrust duct. The leading edge also got three layers, and the trailing edge has two layers. | ||
 | This is the main hull of the hovercraft. It measures 4 feet long by 2 feet wide by 3/4 inch thick. Most of the top deck has been covered with 1/32 inch birch plywood. | ||
 | The 1/32 inch plywood deck is very light and makes the hull very rigid.. | ||
 | I glued 1/8 inch by 1/2 inch strips along the sides of the hull. These strips will provide a solid place to anchor the top side of the skirt and they will also protect the outside part of the hull that will likely take the most abuse. | ||
 | Now the lift air holes have been cut out. The larger hole feeds air underneath the craft, and the smaller hole channels about one tenth of the lift air into the skirt itself. | ||
 | Now all the styrofoam pieces are glued in place. The large piece of styrofoam centered directly in front of the large lift air opening is not called for in the plans. I added this piece (which will be directly under the engine) to give the rear half of the craft greater flotation. | ||
 | Here are the strips of plywood which will anchor the underside skirt attach strips. These are 1/32 inch birch plywood. | ||
 | Another view of the underside of the hull. |
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