Ok, quick question: I'm getting ready to cut out the skins for the foam wing of my latest world-beater. Do I cut them so the grain is parallel to the leading edge or the trailing edge? I'm guessing the leading edge but it's been awile since I made a sheeted foam wing. 

Thanks Clint, that sounds 'bout right. That would keep the grain parallel to the curve in the airfoil and straight with the thinnest portioin of the wing (the TE), possilby adding a little warp resistance. But as you mentioned, not a big deal, I'm probablly just tripping over mouse droppings here. Hope all is well in NorCal. 

You can make the grain parrallel to both edges by putting a tapered piece in between the two edge pieces, you will have to put a tepered piece somewhere..

I believe the best way to align the grain is to make it perpendicular to the spar.  This would maybe be the most difficult way.

Sorry, my dyslexia set in.  Yes, parallel to the spar was what I meant to say. 

No you don't.

If the wing is tapered, how do you get away without using angled or tapered piece of sheeting??

Cheers Neville

If the wing is tapered, how do you get away without using angled or tapered piece of sheeting??

Cheers Neville

Read Mark's last post, except I line my sheeting up with the trailing edge. That about covers it. Why would want to make such a simple process WAY more difficult by trying to insert tapered pices? I mean, It's fine if you want to do it, but why would you want to?

the sheeting as I understand it, lies parallel to the leading edge, the trailing edge is just trimmed off allowing the grain to run at a slight angle relative to the trailing egde

Then you are STILL using an angled or tapered piece of wood! It might not be in the middle of the wing, but its still tapered!  . Surely its better  to join-up and sand all the sheeting before attaching to the ribs? Sanding sheeting joints when already attached to the wing, can give you hollows! That starved horse look


Cheers    Neville

Build an Adimisin wing that is sheeted with no spar.  Frame up the wing in a Lincoln Log Jig.  Lay out the sheet wood on the bench a little over size with the sheeting grain in proper directions.   Have a bunch of weights, pins and whatever else you can think of.  A good supply of really slow cure epoxy.  Put the epoxy on the frame work, ribs, leading and trailing edge.  Lay the sheet in plane and start pinning to hold in place.  Start putting weights on the surface  to make contact.  It takes times that is why  I use slow cure epoxy.  When you are done make sure you have not put any twists in the wing.  The next day or two go remove the weghts and pins.  Turn the wing over and look at all the joints.  If done properly there will be no gaps.  You will also see the panel is a lot stiffer.  Now you do the sheet on the uncovered side the same way.  Yes it will take a week or more to do it right.  But, when done you will have a fully sheeted wing that is very stiff. 

The other alternative and I have used it on quick builds is to use white glue.  You have to mark your sheet where the ribs, trailing and leading edges will be.  Also the spar if there is one at the surface.  If the spar is not into the ribs to make a smooth surface, do so even if you have to cut the notches deeper.  Now you take the bottle of plain ole Elmer's White Glue and put a coat over all the areas you have marked for gluing on the sheet balsa.  While it dries do the same on the wing frame work.  When and only when the glue has dried do you do the next step.  Get an iron and turn the heat up on it.  After it gets hot put your sheet of balsa on the wing where you want it.  Use a pin or two to hold it in place when you start.  Now start at trailing edge and start ironing.  Go slow as you want the heat to activate the white glue.  When done and you have taken your time the sheet should be permanetly adhered to the structure.  I have done it and know it works.  But like anything it takes time and patience.

Any questions PM me .

Doc, to your reply #16...

Elmer's (yellow) Carpenters' glue is an aliphatic resin. The white isn't. The yellow cures waterproof; the white doesn't. Heating the white speeds up its cure by boiling off the solvent: water.

Dozens of years ago, possibly in RCM when it was still around, a building tip pointed out that aliphatics "final-cure" slowly. I seem to recall the article claimed it took several days for aliphatic to "final-cure" completely - a chemical change - at room temps. Heat speeds up the "final-cure" reaction. Ever since, I've applied LE sheeting on C-tube/D-tube wings as you described, but with aliphatic. The yellow Elmer's is pretty thick - it can be thinned with water, but don't go overboard. A mix of one part water to three parts aliphatic should do.
 
Serious jigging is really worthwhile when heat-setting sheeting, as it ain't gonna move after the heat works on it. Pressure on the $Kote iron assures full, continuous contact while it kicks. 1/16" sheeting seems to work out best; thicker doesn't allow the heat through as dependably. You should have the glue lines damp enough that you hear the sizzle when it does kick. Not soggy, just about dry to the touch.

The recent FM article on Brickhaus' Fairey Barracuda (scary name?) describes a different method for using slightly thinned aliphatic. Worth a look, to inspire some thoughts.