By Randy Treadwell
Winter flying can be fun with a simple way to make skis for your airplane. Here are some simple steps and photos to help you.
The object here is to make a light, easy set of skis. Start with a 2x4 to make the mold. Band saw the shape of the ski on the 4" side of the wood.To make a quick smooth molding surface on the 2x4 mold, I used packing tape. Epoxy or resin
will not stick to it. After light sanding and
application of the packing tape on the
mold surfaces, clamp the top and bottom together, and then use
screws to pull the mold halves tight to each other. Your mold is now
ready to use.
Now select the materials to make the skis from. I like epoxy because it is less stinky and a little stronger. Resin will work. After selecting the liquid part comes the material. Simple fiberglass tape 2" wide was what I used here. You could use carbon fiber, Kevlar, or some other special materials. Fiberglass is flexible and will do well on uneven snow. The other materials are stronger and stiffer as well as lighter. The cost goes up also, but I don’t see
better performance needed. I used 3 layers of cloth in the lay up. Make sure the entire weave is wet. I use a cardboard sheet to wet each layer one at a time and then move it to the mold. As you tighten the screws, some epoxy (resin) should squeeze out. I use the oven to cure the molded parts by setting the kitchen oven to a low setting under 170° for 20 min. If you do this with resin, you may be run out of the kitchen because of the stink. You can let it cure at room temperature for a much longer time.
After curing, remove the screws and pry the 2x4 mold apart. You will have a part that needs to be trimmed to shape. I used a band saw, but a scroll saw or handsaw will work. To attach the skis to the landing gear, I used a plywood block with a hole in it for the landing gear. When you glue the plywood block on the ski, sand the top of the ski and use some small scraps of cloth to bond the block to the ski by going down the side of the block and out onto the top of the ski. Use the same material you used for the ski; it will bond the best. I also installed a small block aft of the gear mount to make a small light wire brace to the bottom of the fuselage. That will make it easy to keep the ski in the correct position during flight. Make sure that you have more ski behind the gear mount just in case it comes loose so it will hang in a safe position for landing.
I made these skis in 2 work sessions of about an hour each. I cut the
mold and made 2 skis oven-cured in under an hour. The mounts and
wire rear frame took the second.