Extremely in-depth link for costume's from world war II. It breaks it down to: USA, Germany, and Japanese.
It further goes into what a foot-soldier or soldiers of that war wore; from personal items, to badges, boots, shirts, helmets and so on. You can even buy the stuff!!
This link has all the books you might want to buy. Another great resource.
Various tilt-wing/rotor, etc (not from 1940's... but from 1950's)
PROTOTYPES from the 1940's