I built a Super Chipmunk over the winter and found the inner wing to be warped on it's first trip to the flying field. I am sure it was straight when I built it and attached it to the fuselage. It may have showed up when I Monokoted the wings, I don't know. Regardless what caused it, it was there. I tried heating it with my heat gun and twisting it, a hot towel around the wing and twisting it, no improvement. The balsa on this SIG kit is really stiff and I was twisting it to the point where I was hearing it creaking. I really didn't want to write this plane off as a "it's okay but will never be a great flier", I spent too much time on it. The inner wing trailing edge was about an 1/8" to 3/16" high at the wing tip. It flew with the inner wing low, I could see the top of the wing in level flight, and it would lose line tension coming out of an inside loop. I didn't dare try an outside loop. I decided to try to straighten the wing by putting weights on it. What I did was block the fuselage up between the landing gear and at the tailwheel so wheels were off the floor. Then I also put a block under the trailing edge of the outer wing just until it was high enough to touch from the floor. I folded two bath towels and put one on the main spar of the outer wing and the other on the trailing edge of the inner wing. I folded them so that they were thicker toward the trailing edge so I could sit barbell weights on them without them sliding off the back of the wing. (If only I would have taken a picture to show) I put about 15lbs. of weight on each wing and left it sit for about 3 days. A litle better, but not enough. I set it back up and left it sit for about 5 days. Still not enough. I did it again for another 4 or 5 days and that was enough. I also heated the leading edge of the inner wing with my heat gun once or twice while it had weight on it. The warp hasn't come back. I'll keep an eye on it and if I need to I'll put it back on "The Rack" to bend it back. It flies great now, I can't see the top of the wing in flight and the lines stay tight.
Topic: Wing Straightening (Read 1057 times)