Alright, i have a Goldberg Superchipmunk with a O.S. FS-91 engine, i had a hard landing (in a tree haha) and it took a chunk about 3 inches long and 2 inches tall right on the front airfoil part of the wing, i managed to find most of the wood but there was still a hole, so i tried something new, i got some expandable foam spray, some clear flexible pastic, and some wood filler, i covered the holes with the plastic foamed the inside of the holes, once it dried i sanded the foam so it was flush with the remaining wood and then put wood filler over it and sanded it till it was flush also, would this process throw off the balance or anything i have pics i dont think it did anything to it when it comes to weight except maybe an ounce on the right side of the wing. please help!!!!!!