True, but if the outside surface is sealed, how will the moisture get in there?
Also, not all epoxies are brittle. Depends on the chemistry of the resin and the catalyst/resin mix.
Without a substrate (fiberglas, carbon fiber, etc) no resin I know of will add any appreciable strength to the structure.
I can assure you, if and when I construct another wooden wing, it will again have a suitable epoxy coating applied to seal against moisture. Most likely West Systems with slow hardener. On both sides, like my existing Tailwind's wing. It works for boats - good enough for me... after all, boats float, at least for a while :-)
Yes, the resin adds some weight, but IMHO I wouldn't say a LOT of weight (unless you just plop on gobs of the stuff and do not spread it with a squeegee or brush). I remember Jim C. saying that multiple coats of West squeegeed on were lighter than filler when filling up the FG deck cloth, prepping for primer/paint.
I believe him.
DAL
On Feb 14, 2012, at 1:07 PM, Richard wrote:
A couple of detail points about epoxy treatments:
The phrase "epoxy saturation" is extremely misleading. Epoxy doesn't "saturate" into wood more than a few hundredths of an inch. For the most part it's a surface treatment, leaving the core of the panel quite unprotected from moisture.
Epoxy, by itself, is heavy, stiff, and brittle. It adds no real strength to the structure, but does add a lot of weight. Being brittle, any flex can cause small cracks that will allow moisture to enter the structure.
It's the glass that does all the work here. It adds weight, but also a lot of strength. It holds the epoxy i place and keeps the finish from being so delicate that it will crack when flexed.
Having said that, please don't think that an unsupported (except by ribs) fiberglass skin is a direct replacement for plywood. Fiberglass structures get strong enough to carry a load long before they get stiff enough not to distort under that load.
I will continue to support the Drawings accomplished on Steve Wittman's O&O. There is at this point an accurate dimensional computer 3D drawing of the Fuselage...
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A couple of detail points about epoxy treatments: The phrase "epoxy saturation" is extremely misleading. Epoxy doesn't "saturate" into wood more than a few...
True, but if the outside surface is sealed, how will the moisture get in there? Also, not all epoxies are brittle. Depends on the chemistry of the resin and...
Dave for what it's worth, the Tailwind wing is not sealed, it has a multitude of drain holes at the trailing edge. I do agree that coating every thing with...
John, I hate to drag this discussion on more, but my wing is coated on the inside as well as the outside. So the wood is coated (dare I say sealed?). Yep,...
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Dave, I have thought about the drain holes in the wings and am thinking that those holes are put there to vent each cavity rather than to drain moisture ...
Dave, I have the wing covered in plywood and now filling the staple holes getting ready to put on the fiberglass. If I had waited two days to staple on the...
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