RE: Alfa Model Mig 15
Not needed. The airframe is just fine as designed. The problem is the paint. You must sand the area where the wing attaches, and poke a few holes in the area with a straight pin. This will give the epoxy something to bite to, as it doesn't stick to the paint very well. The wing root fillets cover this area when you're done. You will also want to sand the wing spar joiner and clean it well before gluing.
Tim