guten Morgen Burkhard..
Responding from your second to last post. The wing has polyhedral, The upper outer panels that support the ailerons have a dihedral of a few degrees, in addition the aileron,
which is very deep, has what I would call inverted undercamber. I would guess that this provides some level of washout, which is a very good thing.
In addition, the wings are parallel to each other, since there is a great deal of positive incidence, the upper wing is pushed back some to form a reverse stagger.
Here is a photo that shows the Ilya Muromets in flight. What is interesting is that, like I read, it flies nose down.
More later.
Cheers, Sal