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PHOTO 1


skins were approximately 3


⁄32


composed of an inner layer of fiberglass, the intermediate “strength” layer of


-inch thick and “Airex”-


type foam and an outer fiberglass/gel coat layer that were joined at the middle of the leading edge with a strip of balsa and a bead of what appeared to be Hysol 9462 (Photo 1). This made me think “simple”, so away we go.


Close examination of the full length spar and end plate showed them in good shape, so the edges of crushed and broken skin were trimmed to straight edges (Photos 2 & 3). Since the other side was not damaged, 3


⁄32 -


inch balsa sheet was soaked with an ammo- nia/alcohol mix, wrapped around the lead- ing edge, and allowed to dry. Four sheets were needed, with two each for the bottom and top. When they were dry and formed, the first layer (cut longer than the patch and deep enough to butt up to the spar) was epoxied into place (Photo 4).


When the inner layer was cured, the outer skin pieces, were trimmed to the smooth and straight edges of the break and also epoxied into place using a thick layer of epoxy mixed with micro-balloons to ensure all voids be- tween the existing structure and the re- paired structure were solidly joined (Photo 5). In one of the photos (Photo 6) it can be seen that both the top and bottom skins fit smoothly and well with the existing wing, and that the junction of the skins is offset to the bottom allowing a smooth continuation of the leading edge contour, thanks to the molded balsa. The joined balsa-wing skin edges need to be sanded and filled with a lightweight “Bondo” (I used Bondo’s “Ultimate” materi- al), the skin lightly sanded to give some “tooth” to the resin and a glass layer applied


PHOTO 2


PHOTO 3


PHOTO 4 FLYING MODELS 43


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