Originally Posted by YellowBlueBird
BMatthews, you are right on all accounts. Pressure on the sheeting is most likely what caused the rod to bend. It held the bend and was easy to reshape. It does not stay straight any length of time.
I had to scrap a wing that had built in curvature due to the sheeting. I've been a LOT more careful to avoid the same issue since.
Try some steam or even soak down the wing and put it in a warm environment with some curve in the opposite direction. At this point you have nothing to lose since it sounds like it's not useable in the present condition.
I'd suggest making up a temporary "oven" that is made from building insulation Styrofoam on all sides with a couple of incandescent lights inside as the heating elements. They'll get hot so be sure to support them off the foam to avoid melting the foam. But with a couple of 60 watt lights inside such a box it should get up to well over 100F inside. That and the wetted down wood should give you a reasonable chance of forcing the wing to warp the other way and come out straight.
Another thing you could try is to soak down the sheet wood with a strong ammonia. Not the sudsy wash day stuff. Some industrial strength basic ammonia. Prop the wing in a jig that holds it slightly over bent in the desired direction then swab down the sheeting with the pure ammonia. As the stuff on the wood dissipates hit it again with a generous application. Two or three times of this should let the ammonia soak well into the wood and soften it enough to stretch and compress as needed. After it dries so it's no longer wet or smelling of ammonia the wood will be back to it's normal strength. But keep it locked into the jig until then.
Over a the next few days some of the locked in tension might make it warp a little again or it may not. Hard to say.
If the wing uses webbing with the sheeting to form a "D" tube you will likely need to bust out the webbing. Or at least cut the majority away. That'll unlock the "D and allow the wing to take and hold the new shape. After you know it's stabilized straight then you can replace the D tube webbing.