Corsair Paint Schemes

From my understanding, and my source may be wrong, is that they used the topside color on the outer wings in order to blend the aircraft better with the topside color of a carrier deck, if so deployed. Otherwise, the light underbelly colors might tip off a search plane that a carrier was there.

Mississippivol is correct. The reasoning was to make the aircraft on the deck, and therefore the carrier harder to spot from the air. I'm not aware of any Corsairs on which the undersurface color (light grey on N.S. blue gray or white on tri-color aircraft) was carried all the way out to the wing tips.

 

The folding mechanism on Grumman aircraft (Wildcat and Hellcat) faced the wing underside toward the fuselage when folded.  This meant that they could paint the underside of the wings the underside colour.  The Corsair wings folded straight up, as you know, and the undersides faced outward and needed to be camouflaged.

Edit:  Some of the Goodyear built FG-1's were produced without folding wings.  Folding mechanisms could also be removed to save weight and improve performance for land-based Corsairs.  Theoretically, a land-based squadron could have painted the entire lower surface the lower surface colour.  I doubt it, though.  Navy mainenace crew painted by the book, and Marine maintenance crew didn't paint anything if they didn't have to.  If I saw a picture of a Corsair with the underside of the outer panel looking the same shade as the underside fo the fuselage, I would believe it.

The aircraft were painted at the factory per Navy specifications at the time of construction. USMC aircraft also fall under those regulations. 

But the whole source of the outer wing underside color was when the Navy switched to light gray overall on aircraft in 1941 as War was approaching. Flight decks were changed at that time from Mahogany stain to Blue stain. The light gray aircraft stood out markedly from the ships camouflage colors and the order came down, any  aircraft surfaces visible from above, to include the undersides of folded wings, was to be painted in the Blue Gray that was adopted in late 1941. At that time, that would have been on the TBD and SB2U due to their upward folding wings. When the F4U entered production, Blue Gray over Light Gray was the standard and the upward folding wings dictated the outer wing under surfaces in upper surface color. When the transition was made to the tri color scheme in 1943, this practice continued, but in Intermediate Blue instead of the Blue Gray. Early SB2C Helldivers also followed this practice. The above mentioned Grumman aircraft with their aft and inward canted folding wings negated the need for that style of painting.

Thanks guys! All this was really helpful (and interesting!) makes total sense now.