How do I measure the wing incidence? Is the reference a line from the lead edge through the wing to the trail edge? This assumes a line from the furthest point forward on the lead edge to the center of the trail edge. In that case, there is an obvious angle between that line and the bottom surface of a flat bottom wing or a semi symmetrical wing. This means the bottom surface of the wing would be pointed down if the line were used as "level". That seems contradictory. I don't want to be argumentative or take over this thread with my problems, so if there is a book (if there is such a thing as a book, anymore) that could guide me, please let me know. And thank all who have replied to my question. You are greatly appreciated.