Russ:
I am a huge fan of your work. Love the subject and the light quality of this piece. It is wonderfully rendered.
However, before starting the final version, IMHO there are two areas that you may wish to revisit ...
The first is the upper wing. The area around the port aileron and wing tip doesn't look right. It may actually BE correct, but to my eye it seems oddly foreshortened. Gives the impression the upper wing is the same cord as the lower wing. Also, the characteristic angular shape of the Albatros upper wing is somehow lost. That said, rendering these shapes in an almost edge-on view is quite a challenge. Geometrically this could be absolutely correct. It is just that to my eye it does not describe the shape convincingly. Maybe it is just me.
The second is the light on the lower surfaces of the wings. If the light is coming from below and casting a shadow on the fuselage, it seems as if the lower surfaces should be more illuminated. Albeit close to edge on.
Again, just suggestions offered as constructive criticism. The overall effect is excellent, and I do indeed love the painting.
Cheers!
Tom