Well, what is it that you need to Repair? Here I will show how I fixed a Scuffed Wing Tip and also a Crack down the center of the Wing. First I'll concentrate on the Wing Tip. First thing you have to do is add some CyA to the wood to make it hard. Noticed I used thin CyA so that It would soak in. I Use a stuff called "Evercote" Part #400 found at most auto body stores and some Home Depot type stores. It is a Polyester Glazing putty. Basically it's like Epoxy in some ways because you use the putty and then have to add a little hardener to it. Once mixed you apply it over the Area you need to fill or shape. Picture #4 shows how I really poured it on the wing tip. You can let it sit for about 5 minutes and it starts to get hard. You can wait another 10 minutes before you can sand it. Or better yet you can take an Exacto Knife and remove the excess (Picture #5). Sort of like Carving into shape ( Makes for a lot less sanding later.). Picture #5 shows the wingtip after the first Sanding. As you can see not all is filler so a second coat will be needed. I use 150 Grit Sandpaper to get it down to shape and then run it through with 250 and finally with 400 prior to primer. Make sure you sand all the sand paper maks out before you start painting.
Cracks on wings is another story. The repair will be different depending on the Damage. If you have a simple cosmetic crack and it did not go through the wing, then just fill it in with 10 minute epoxy. Use a tooth picks or something else smalle to CRAM the epoxy as deep into the crack as you can. This, of course is would be used only if you didn't break any wingspars or other structures. O.K. People the same wing also had a small crack on the wing next to the Aileron pocket. If you look close at the Aileron/Flap servo box, it does not have a balsa lining (IE. You can see the foam in the walls). If you add a balsa or ply walls to the servo box, then that will make your wing a lot stronger. Since this is a wing from a high speed BVM Sabre, I added carbon Fiber tubes to act as stiffeners where the crack occurred. First make a cut out for where the stiffners are going to go. Make sure the stiffner goes past the crack by at least one and half inches. Fill the bottom with epoxy, place the tube inside and then fill the top with epoxy too. Before it dries, remove any excess that will bulge or protude from the wing. It is O.K. if it sinks just a little leaving you a small channel to fill. Get that "Evercote" out again and repeat the procedure from Above.
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Ralphs@pcmagic.net.