When I built my P38 the wing tips wound up with wash in in the tips, is this correct?

From : Don Stackhouse

No, there should be some wash-OUT (i.e.: trailing edge higher than leading edge). The correct amount of washout is cut into the bottom edges of the ribs, so the washout is correct if they all sit flat on a flat surface.

If you don't have everything held flat on a flat surface when gluing on the upper wing skins, you can end up with warps. Also, it's possible for the wood to want to do this even though you did your best when putting the wings together. Fortunately it's fairly easy to fix. Just heat up your covering iron (about 350deg. F works well), twist the wing in the correct direction, and run the hot iron all over it, just like re-shrinking a warp out of a plastic film-covered wing. You can straighten out some surprisingly big warps this way.

Don Stackhouse
DJ Aerotech