On to the wing.
First picture shows what it should look like after being cut and the foam removed.
Picture two showing the bevel cuts and paper removed from the forward portion of the top wing skin. You'll want to roll this section over the edge of the table to establish a curve. If you don't the airfoil will kink slightly when you fold things over.
Spars get glued on. The wider spar is scored down the middle, as per the plans, then glued and folded over on itself. This is the main structure of the wing. I haven't found it necessary on the prototype, but if you want some extra strength you could add a dowel, arrow shaft, or piece of wood along this spar between both wing halves. The thinner spar just helps establish the rounded curve at the leading edge.
The cutout in the lower skin for the aileron gets folded over and glued. (c-fold) Before you fold the wing over, crush the trailing edge of this spacer slightly or you will have a slight gap on either side of the aileron bay.
Next we start the airfoil. The paperless skin makes for a really smooth curve, but it is harder to get consistent curves from one side to the other. It might be easier to get a consistent airfoil if you glue both wing halves together before forming the airfoil, but I have not tried this method yet. Remember to pre-curve the top skin over a table edge or else it may kink as it bends over the spars.
Spread hot glue along the leading edge bevels and fold the top skin back until it touches the first spar. The hot glue will help melt the foam and form the curved leading edge. Once the leading edge has cooled, let the top skin lift again, spread glue on the first and second spar, then press the skin down until the glue has cooled. Try to keep even, downward pressure along the leading edge when you do this to keep the lower skin from lifting off the table and changing the airfoil.
Now you can squirt some hot glue in the trailing edge and press it flat until everything cools.
If you haven't already, now is the time to glue the wing halves together.
On my build I installed the servos first, but the arms get in the way, so I would recommend doing it last.
To join the wing halves, put a strip of packing tape across the seam on the lower skin. Hinge it open on this tape, coat the wing root generously with hot glue and then fold it back together, doing your best to align both halves. If you've built an FT wing you'll know how this works. There is no dihedral, so you don't need to prop a wingtip or anything. The last thing is to glue in the wing base. This is the cutout from the top of the fuselage and it helps keep the wing aligned when rubber-banded on. I make sure my glue gun is really hot, spread glue generously across the wing base, then press it roughly in place on the wing. Then, while the glue is still warm, I set the whole assembly lightly on the fuselage and nudge the wing until it is square to the plane.
Here is the servo setup I have. Two 9g servos, FT control horns, two 6" servo extensions, and a Y-harness. For one side I plug the servo wire, extension, and y-lead together then tape the connections. Feed it from the servo hole, along the spar and out the center hole of the wing.
For the other side I run the servo wire and extension. Since we're installing these after the wing is folded you need a long enough extension wire to pull the connector out the center hole in the wing and plug it into the Y-harness.
From here it's just a matter of gluing the servos in their pockets, making pushrods, and installing control horns. All this is pretty standard FT procedure.
And we're done! The wing base nestles in the cutout on top of the fuselage and rubber bands hold it all on.
If you wanted to add a little dihedral for a more docile flying experience you could always trim the upper skin slightly and prop up a wingtip when you glue the wing halves together. Personally, I don't think this is necessary and it takes away a little of the flying personality of the Spirit of St Louis. It's not a hard plane to fly, but you do have to fly it all the time, no letting your mind or thumbs wander, else the plane will go with them. The choice is yours.
