Aquila XL balsa shear webs with epoxy???

[ferincr]

Hi, I started the assembly of the spars for an A XL and according to the instructions the balsa shear webs should be epoxied.
I mean between the two spar caps is filled with 1/2" vertical balsa shear webs (epoxied), then where the wing rod assembly is, there are the two birch ply shear webs (epoxied) and contiuing those( and covering the "internal 1/2" balsa shear webs) the regular vertical grain balsa shear webs sandwiching everything.
Those are the ones I'm asking about, I mean this spar assembly is rock hard already do those last balsa shear webs need epoxy? don't just yellow wood glue would do?
I know I won't hurt to have too much epoxy but if it is not nessesary I would rather use something simpler.
Fernando

[mhmitchell]

Actuall the shear webs are very important to the strength of the wing. I believe they are there to help distribute the compressive forces of the wing. I have noticed that carpenters glue never really loses its flexability so epoxie (30 minute not 5 minute ) is the way to go. You might try slow super type glue but recently have discovered it is quite brittle and might fail under extreme loads. The problem with pro bond types is that it expands too much when it dries.

[ferincr]

Thanks mhmitchell,
Actually I was trying to get away without using epoxy, because I find it messy to work with, but I laready did one of the spars and I think we (epoxy and me) are learning to work together.
Fernando

[mhmitchell]

See http://www.rcgroups.com/forums/showthread.php?t=358208 in this forum. It talks about the West System epoxies. It IS expensive but a little will go a long way. Its thinner and can be thinned even more. Its great as a laminated resin in case you get into that. Its good for sticking balsa ro wing cores. And as a finished surface.

But I use carpenters exclusively for laminating balsa shetes and for building the fuselages where super strength is not required. Mainly I am sloppy and always have drips to clean up so carpenters glue sands well and is easier to wipe up with a paper towel. So dont throw the yellow stuff away. By the way fast CA can be used to hold pieces together while other glue are drying. Just leave a bare spot in a couple of place and after everything is aligned a small drop will do ya.