This is great morvael thanks. Only slightly hijacking the thread, but could you also explain how new airfield resupply works? My impression is sorties draw first from airbase then from nearby towns (determined at beginning of turn or dynamic?) and then finally through rail supply to a permanent source. If this is correct, does the last option expend vehicles and if so how many and where can we see this? What if a town has only supply (presumably automatically converted to ammo)? Is fuel separately drawn from rail? Finally, does rail inefficient affect this just-in-time supply and does this afffect supply rail cap (and if so where can we see currently available supply rail cap)? A lot I know but it is quite opaque to me as a newer player, thanks!
Yes, a bit may be drawn from airbase, more from cities nearby. It does not expend any vehicles, nor is affected by supply rail cap though.
I never had a good solution for airbases and groups they resupply. If the airbases carry extra supplies that depend on the number of planes, then it's easy to abuse the system by removing aircraft from any base every second turn. If they always carry a lot of supplies, they become vehicle hogs. If there will be limits to resupply (for example distance limits), then it's too easy to block aircraft from flying at all. I guess the only good solution in this model would be to make air groups "carry" their supplies with them, and resupply them like ground units.
Towns and HQs always carry generic supply that gets converted to supply and ammo. Generic supply is both supplies and ammo. But fuel is separate resource at town/HQ level, so it's drawn separately.