[Scharnhorst1943]

most US bombers use a desert (PTO) and a summer (ETO) folder

except B-17D, it uses a summer only

of course the desert maps use the summer folder

Huh what? Please explain... so if I put a skin in both PTO and summer in my mods folder I can replace both US and international skins?

Not exactly ... well kind of ... see below

In your 3do/plane folder you have all the aircraft, and you should see folders like the following:

B-17D(USA)
B-17D(Multi1)
B-17E(USA)
B-17E(Multi1)
B-17F(USA)
B-17F(Multi1)
B-17G(USA)
B-17G(Multi1)

All folders for (USA) are for any of the American branches (USN, USAF, USMC). Any folders marked (Multi1) are for any other country, either Allied or Axis.

Within each of the above folders, you can have the following folders:

Summer
Desert
Winter

So that gives you up to three skin options per plane type, per branch. However, having your skin appear depends on some additional factors ...

It depends on the map you are flying on. The way the game is set up, Europe, Russian and Mediterranean maps use the SUMMER folder. Pacific maps use the DESERT folder. And any Winter map uses the WINTER folder. However, if the map maker did not specify in his map, it will use the SUMMER folder as default. This can be changed but I don't remember where.

Some planes cannot have a (multi1) folder. Other planes cannot have a DESERT folder. For example:

The F4U1A plane cannot use the desert folder. It ONLY uses the summer folder regardless of anything else.

Most of the Russian planes, like the Li-2, cannot have a (Multi1) folder. Whether you are playing for Russia or US or Britain, it uses the same skins.