Hi Paul;
You have a pretty good description, but without having the model right in front of me, it's hard to be really precise in determining what it needs. The flap issue is definitely causing you some problems and needs to be addressed first. Sounds like it may have been made form some softer, punkish wood. The flaps and elevators need to be very stiff, and might not be the best place to try and save weight with really light wood, which can be soft. If the outboard flap is OK, I would concentrate on repairing the inboard flap. This can be done sevral ways. One is to make a completely new flap using stiffer wood. Another would be to steam the old flap and get it to lay flat. Once you achieve that, you can take a piece of hard, stiff wood and inlay a sort of spar in the middle of the flap running span wise. The spar can be 3/22 or 1'8" wood, cutting it as straight as you can possibly make it, and sand one edge flat.. Cut it wider than what you would need by about 1/32" Cut the slot on the flap as nicely as you can. Take your time and make several cuts. start and stop the slot about an inch from each end. Sand the slot to accept the spar and make it just snug, where you don't have to force it in. When you are satisfied with the fit, pin the flap to a plat board laying on some wax paper. Next apply some Elmers glue to the spar and work it into place. Push it all the way down and pin it into place. Let the glue dry thoroughly. If you can, trim the spar while the flap is still pinned down, carefully, then block sand it flush with the surface. When satisfied, pull it off the board and sand the other side. It should still be flat and be ready to refinish. That may sound like a whole lot of work, but if you don't have wood for a new flap and want to get at it right away, it's what you can do right now, and really won't take much longer than building a new flap. While you have the flap off, you can sight the wing to see if it's straight. You do this by looking at it from the back of the airplane. Raise and lower the tail and put the trailing edge in the middle of the top and bottom of the wing surfaces. If there is a twist in it, you will see it. This takes a bit of practice. Sometimes just sighting down the trailing edge from the tip will do oit also. If it's twisted, twisting it the opposite way and heating the wing gently with a monokote irona to shrink the covering will help hold the adjustment. Just tweak it until you see some wrinkles, and then apply the heat, relax, and then let it sit a few minutes. This can work with iron on coverings and with dope finishes. Steaming it can work also. Again, it helps to have the patient right here on the table, but this all should get you started. GHood luck with it.
Type at you later,
Dan McEntee