Mending a Broken Wing
For those extreme hits that break a foam wing (or other parts) in two or more pieces, repairs can be quite simple. Some of the great traits of foam are that it is usually easy to piece back together and each part fits together quite well.
Step 1. Mix equal parts of epoxy (15- or 30-minute) on a disposable surface, such as a plastic-can lid. Mix well, and apply just enough epoxy to cover the exposed ends of the break.
Step 2. Place some waxed paper under the wing pieces to keep the repair area from sticking. Use some masking tape to hold the parts together while they rest flat on the work surface, on top of the waxed paper. Using a paper towel and some denatured alcohol, wipe away any excess epoxy that oozes from the repair. Check again after a few minutes for any extra epoxy that may have made its way out over time.
Step 3. After the epoxy has set, remove the tape and use a sanding bar to smooth out the repair. Using some fine sandpaper, sand the surface smooth and flush with the rest of the wing surface.
Step 4. Cut a slot across the break and then insert a 1/2x5-inch piece of 1/32-inch plywood to act as a brace to strengthen the wing. Use slowsetting CA and insert the plywood so it is below the surface of the wing. Let it dry.
Step 5. Once the glue has dried, use some hobby filler and fill in the broken area and the brace slot. Let it dry and sand it smooth.
Step 6. Apply some matching foam-safe paint to the area, and let it dry. The repair is complete, but if you like, you can apply some decals over the repair area to completely cover the mended section.
MATERIALS NEEDED
For most repairs, the two most important items are glue and a sharp hobby knife. A good selection of CA glues will be needed
(thin, medium, and thick) along with some accelerator (kicker); for high-stress areas,
15- or 30-minute epoxy will fit the bill. A sharp hobby saw is perfect for making smooth crosscuts in the wood. A good hobby knife with extra blades will be used for all other cuts. When it comes time to smooth things out, you’ll need a couple of sanding blocks or bars with medium (100- to 150-grit) and fine (220- to 320-grit) sandpaper. If you need to remove large amounts of material, a good razor plane is helpful. Also, you’ll need a pencil and pen for marking, along with a ruler, extra balsa, and matching covering material. A covering iron and heat gun will also be required for applying the covering material.