Wow, what a great feedback! Thank you all!
So I should continue immediately with:
Upper wingThe upper side is taped ...

... and painted:

After painting the ribs with wood brown the bottom side is also masked:

With help of a floating mask ...

... I pianted the shadows of the crosses and lighten all up:

The final result after painting the bottom side

... and the upper side. My typical fault: a bit to much paint!

The tail skid is painted in wooden acrylic paints:

I cutted the control horns and soldered a 0,5mm pipe to them ...

... to hold later a Gaspatch tunrbuckle of typ "one end":

The control "wires" are prepared with brass tubes and turnbuckles, which is easier outside of the model.

Little progress for a lot of work!
Cheers,
Bughunter