Balsa sheeted foam wing repair - RC Groups
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Aug 29, 2004, 08:18 PM
jcosta's Avatar

Balsa sheeted foam wing repair

When I landed my 2.2 m ASW-20 (10-15 years old) today, I got a lateral gust and touched a wing tip and did a partial cartwheel.
Looking at the plane I found a small crease on top of one of the wings, with nothing underneath. The crease is in line with the servo well, that is, unfortunately, aligned with the beginning of the aileron.
The wing still feels solid but must obviously be repaired. It is balsa covered white foam.
It was suggested to try a covering iron first (the wing is covered with Monokote or similar) to see if the crease goes away. Somehow I feel this will not be enough...
What are my options?
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Aug 31, 2004, 11:51 PM
Go get them Meg!
lrsudog's Avatar
I usually repair something like this by de-skinning the crease by making a cutout in the shape of a diamond to give the strogest joint possible, shaping a new but slightly too thick balsa skin replacement, and glue it in place using micro balloons in epoxy (Which fills any little gaps in the foam). Then I block sand it even and re-cover it.
Sep 01, 2004, 05:06 AM
jcosta's Avatar
Thanks for the suggestion!
After removing a strip of the covering I found the veneer was not split along the crease, just compressed.
I ended up injecting a little water in several spots along the crease and ironing, which "puffed" the foam and straightened the crease. Then with a long needle I injected PU glue in the same spots, making sure to apply it all along the crease by injecting at a very shallow angle and I applied weight (phone books to keep the airfoil).
Now I have applied balsa filler to cover any imperfections and when it finishes drying I'll sand and patch the covering.
A sticker from my club will go on top of the patch until I get the courage to remove all the covering and apply new covering.
Anyway, the wing is perfectly solid now.

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