HighPlains
Posts: 2640
Joined: 3/2/2003
From: Over da rainbow,
KS, USA
Status: online
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It would be difficult to deal with compound curves with bagging.
However, thousands of Formula Ones were built with glassing after the wing construction.
How I would do it:
Prepare the skins, align balsa grain with leading edge, sand smooth both sides before bonding to cores. Use 6 to 8 lb. wood, with 3/32 on top and bottom. Glue some .007 carbon 1/2" wide to the bottom skin on inside before sheeting cores. Put a strip at least half span at the thickest point. Doesn't need any on top skin, since it will be in compression only in racing. Finish shaping wings to get ready for glass.
I prefer polyester resin because it gives the hardest surface, but stinks like hell. Glass the bottom surfaces first with 3/4 oz. glass. After it sets, sand around the edges with 320 paper to cut off the glass at the edges. Then glass the top with a bit of overlap on the leading edge. When putting on the resin, just mix it up, and pour it on in the middle of the surface and squeege it to wet the cloth, working out the wrinkles as you go. Squeege it as thin as you can.
After you have the glass on, squeege on a second coat of resin and let it set. At this point you can wet sand very lightly to skuff the surface up slightly. Go ahead and cut the ailerons, insert torque tubes (from bottom) and cut hinges. Fill behind the torque rods and sand smooth. Also do the landing gear blocks, and wing hold downs at this point. If you use epoxy, be sure it is compatable with the resin system. If not sure, you can smear a barrier layer of white glue over the epoxy.
Now add the center section glass. Use three layers of 2 oz. cloth, with the widest layer on first. Make the first layer widest at front (10-12"  tapered to about 5-6" at trailing edge. Second layer is about 2/3" the width of the first, and the third is about 1/3 of the first. Place all three layers on the same time and resin it on with light squeege action. To get a smooth surface, place the waxy surface of wax paper onto the wet resin and smooth out the air pockets. Let it set up, then peal off wax paper and throw away. Trim and sand afterward, then do the other side of wing.
After the center is glassed and lightly sanded, you may want to squeege on one more coat of resin, and wet sand with 320. Use a 3M sanding block, sanding with circular motions. You can achieve an amazing finish with a bit of work, but be careful not to sand through the glass. When 80-90% of the surface looks dull when wiped down, you are finished and ready for primer.
It is a bunch of work, and the wing performance depends on how well you shape it and sand the surface. But you can also make minor changes over molded designs that are locked into what ever the designer thought right at the time. For instance, you might consider slightly more area, washout, or change to wing sweep.
As far as surface shape and finish, the leading edge and first 1/3 of the airfoil is critical. The rest of the chord, no so much. Make and use templates on the leading edge, while on the rest use the shadows moving across the surface when you hold the wing up to late afternoon sun and slowly rotate the wing. If the shadow skips and jumps, you have sanded flat spots and the performance will suffer. If you get the leading edge too high or too low, the performance will suffer. Take your time, sand and shape it over the course of several days and you will do a better job.
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Glassing wing? - 
