Classic shot!
The outer wing panels and vertical tails were built by subcontractors and shipped to the assembly plants pre-painted. Like Rich says, even though all were painted Olive Drab, the standard varied widely, and some paint faded faster than others, or shifted to different shades. Certainly they weren't gonna shut down the production line just because the paint was a slightly different shade. I've even heard of "transitional" B-17s in bare metal with OD outer wings and verticals, and even some that had the pre-painted parts re-painted silver.
Another thing clearly shown in the photo, which 99.9% of B-17 models get wrong, is the staining around the hot air vents aft of the engine nacelles. Most modelers paint big black streaks coming out of them, as if they're exhausts, but you can see that the area aft of the vents is clean..the hot air actually keeps the area clear of the oil staining from the engines.
Quote:
Interesting to me is that 3 guns (2 waist guns, 1 at radio(?) position) are pointed aft and up as if they are shooting at an approaching aircraft.
I wonder if this was simply the "at rest" position for the guns. I'm not sure how well balanced the mounts were, but left alone it seems to me the guns would naturally sit with the barrels pointing up, and the slipstream would push them back.
SN