make a dragon fly?

I'm trying to make a dragon fly. By making its wings roll left and right, it looks like it's flying, but I also want to make the wing flap move so that the wing is completely outstretched. No matter what I try, the flap moves away from the rest of the wing even though the vehicle of the flap is the wing.

Grateful for any help you can offer.

I am having the same problem. I'm doing the 3-2.6 exercise with the dragon and the blimp. This is tough.