jest a thought from a texture mapper dood from long ago ..who loves the B-17..
When I did the textures for AW bare metal planes ..I took my cues right from photographs of the planes I could find ..(I have a LOT of them)
..since game engines can't do all the reflections there are, as the texture mapper ..you have to put some in. Not too much .. just enough to hint at it ..and the human eye-brain interface will put in the rest because it expects it to be there.
ie: a little brighter, more contrast on topside ..a little duller, less contrast on the bottom side ..a 'horizon' line down the fuselage (I chose level flight attitude, cause that's where you see them most when yer flyin em')
..a little 'concrete' color below the horizon line, darkening as the texture progressed to bottom center of fuse, cowl, etc.
For topside, you gotta mix a lil blue in ..these planes dint fly in massively bad weather (solid gray skies) if they could help it.. it was partly cloudy or clear on best days.
For examples you can check out some stuff still up at +mia's web site dedicated to the San Francisco Veteran Pilot's Association:
http://www.worldwar2pilots.com/ww2GrayEagleHangar.htm-GE ( combat planes weren't museum peices, they leaked, had patches,
..and that new aluminum glaring shine dint last long, but bare aluminum even 2 years old still reflects rainbows of color )
