The minimax stress analysis (which was done on the original "1984" version I think) shows the safety factor of the forward ply box fuselage at greater than 10x (see page 19 of attached analysis) so the absence of fabric there should not be a structural problem.
I think many methods of covering would work fine but that is a large area of glue surface. IIRC I put glue on the entire surface and glued down the edges and the "low spot" (the concave area created by the "buckling" of the ply when pulling the fuselage sides inward toward each other) then shrunk it a bit and then activated the rest of the surface area by brushing MEK or acetone through the fabric. It is easy to get "lumpy" glue under the fabric on this large surface area and thinning the glue and being conservative on the amount applied is probably a good idea. Perhaps it would even work fine to not apply any glue before the fabric (except around the edges) and simply brush a thinned coat or two on afterward.
Note that if you fully shrink the fabric before gluing down the entire area you may find that it is very difficult to get the fabric to stick to the "low spot" as it will want to "bridge" across it.
Also herein lies the question of to varnish or not under the fabric. I think (but stand to be corrected) most recommend varnishing all the wood and not depending on the fabric and paint to protect the wood. The varnish used depends on the covering system used. Some "activators" are reported to turn "normal" varnish into goo and require a 2 part epoxy varnish to be used on areas that will be exposed to the glue activator/thinner.
As a point of reference I used "poly tak" for glue and used acetone for a thinner/solvent/activator. I also used "common" polyurethane varnish from wal mart (minwax, red devil, etc.) and experienced no problems with the acetone dissolving the varnish. YMMV
In selecting varnish from wal mart or Lowe's you can usually choose a gloss or matte finish. I first used matte because the gloss "sounded" like it would be harder to get the glue to stick to. But then discovered that the matte is simply glossy with "flattening agents" added to it which must be stirred a lot to mix evenly in the product. The next time I used gloss to prevent all that stirring. Other than the stirring I found no difference in the performance of either one. This time I'm using gloss again. |