What is the process for applying leather fillets? They came with my cobra kit. I want to try them but have no idea what the process is.

Pat

Well some swear by them. But the process for me would be pick up the phone call Wicks Aircraft and order Superfil and after receiving the filler walk to the trash can and deposit them. I know that not what you wanted to hear but maybe one of the guys who use them can chime in. That's only my opinion.

  I'm guessing, but I think the procedure is to glue them down with Ambroid or similar, and use the leather as a base for some other material to go over it, so that keeps the fillet material to a minimum and excess weight down. You get a bigger, smoother fillet this way, I think. In the good old days I think it was common to mix balsa dust and glue and put that over the leather, and then sand smooth. The procedure was in the instructions or on the plans of some old stunt kits, if I remember correctly. I have never done it myself, but have a few feet of it around somewhere and might try it one of these days for the same reasons you are. Might be a good idea to pass the technique on so it isn't lost to time.
   Type at you later,
     Dan McEntee

Leather fillets is my second best discovery for making good fillets. First one was West System 105+209+baloons mix. Now I use leather for fillets up until the fillet needs to be tapered. I then switch to West System for tapering. If I can figure out how to make leather fillets taper nicely, I'll use them exclusively.

If needed, the above post addresses it well. The only tricky part can be wrapping around the LE of the wing, they tend to go convex, instead of concave. It really does not show in the finished plane but if you are reeeeeealy picky, it may be an issue. 

True, the fillet does become less concave but this is why they invented 120 grit sandpaper and dowels.  You can sand it right back to the original radius.

Thank you everyone!