I do not want to belittle the work of the volunteers of The Ultimate Sacrifice Memorial Foundation but “My Gal Sal” is painted wrong.
The ships of the 97th Bomb Group were originally intended not for Britain but for the AAF to hunt down U-boats during the shipping sinking crisis of early 1942.
They were painted in an ad hoc rush fashion by Boeing of the then in effect Air Ministry Temperate Sea Scheme for patrol aircraft of an disruptive pattern Extra Dark Sea Grey and AAF Shade 41 Dark Olive Drab, in lieu of Dark Slate Grey for the upper surfaces and Sky under surfaces. By the photographs the paint crews eye ball the pattern and at least two different crews did the painting, one crew did a “straight” edge pattern and one did a “wave” pattern for the disclamation between the upper and lower surfaces.
Here are some color photos of this scheme:
The well repeated landing of 41-9020 piloted by Lt. Dempsy after its collision with Lt Wiley’s 41-9051.



And 41-9023 ALABAMA EXTERMINATOR II about a year later in 1943 as seen in the movie “The Memphis Belle” note how the Extra Dark Sea Grey has by then fade out across the rudder or is a different color.


I think that the Extra Dark Sea Grey and Sky was painted over the Dark O.D. and Neutral Gray in the rush to get them out for in this photo of the 1965 Society of Automotive Engineers expedition to the crash site the top layer of paint has been ice blasted off leaving behind the Dark O.D. underneath.

The Star insignia along with the under wing U.S. ARMY were painted on during sub-assembly and mask off during final painting thus the neat edge.
As far as the blue shade of the under surface I think again this is the Neutral Gray that is left from the years of ice blasting, some paint manufactures made a very blue Neutral Gray.
I think that the volunteers followed the reasonably assumptions of now some 50 years that if it was a British day bomber they were painted in the A.M. Temperate Land Scheme but the A.M. did ordered Catalinas, some Hudsons and some Fortresses in the Temperate Sea Scheme for anti-submarine patrol work and the air force said to Boeing “paint them the way the Brits are doing and make it quick”.
Best regards to you all
Tom