RE: Balsa USA Fokker DR1 1/4 scale
SDP,
I have used windex alot for softening sheeting to make it more flexible, it will keep it from cracking too easy. You want to spray the windex on the outside of the area you want to curve. I spray just a light coat that will only soak about 1/2 way thru the sheet. Once the sheet is glued in place and it dries you will not see any ill effects from the windex. The sheet will start to curl slightly as soon as you spray it with the windex. From my experience this will put less stress on the wing than forceing a stiff sheet to conform to the shape dry. It will want to spring back to the flat surface and can cause warping. The sheet sprayed with windex will dry to the shape it was glued and will put less stress on the wing once dry.
For the pipe you need a fairly thick walled pipe and of course it must be straight. The one I am using is 65" long and is pretty stout. The longer the pipe the thicker the wall needs to be to prevent flexing.
Later!!
Anthony