If you look at the old picture of a Jeannin Stahltaube you see that both of the traiing edges are curved up some. For control one tip is flexed morewhile the other tip is relaxed some. The servo in my model only has to add the power required to change the flex in both tips, adding flex to one tip while releasing the other tip. The control cables are connected to the same hole in the servo arm and the cable loops pass throughthe loopin the other cable, that way if the servo arm breaks the cables are still tied together.

I tried to post above a youtube video of a real taube that shows the wing warping and in flight video.

Clancy