some further discussion on the air units :
air unit builds and spawns will vary from civ to civ. and there's some reasoning behind it
the map is basically divided into 3 distinct regions : Industry, Imperialism, Pacific Islands. each region will allow for a certain set of air units to be built there (or spawned; more on that later). by this i mean that some form of fighter
and some form of bomber will be able to be built in each of the 3 regions. with that said, here are some comments for each civ and their air unit builds :
US : the most advantageous and complex of the bunch. Japan isn't far behind in terms of total available units. but there is a qualatative edge tot he american aircraft.
land based american fighters will be able to be built with the Imperialism resource. this sets the stage for construction of them in Australia, ie the 4 american 'cities' in Queensland. Hawaii, Alaska, Panama and Cuba round of their starting Imperialism locations. and then there's the possibility of the US taking ground on the map, like in New Guinea or the Philippines or China or any of the other Imperialism locales. rationale for having Imperialism as the req'd resource for the US's top fighters is to put them right on the front lines, immediately. consider the USAAF fighters as 'ordered & delivered' to these far flung locations

call it a built-in advantage based on industrial capacity, logistical capacities etc. of course, the one glaring issue with Imperialism as the req'd resource is that it seems that the USAAF fighters can't be built in the US. well, they'll be spawned by a building (ie not a wonder), likely called something like "P-38 Lightning Contract" [or something to this effect]. now, this "Contract" building will require a host of other improvements, starting with Electricity Co which is required for Factory, which will be req'd for Mfg Plant, which will be required for Aircraft Mfg Plant which will be required for the "P-38 Lighting Contract". that was a mouthful

anyhow, these "contract buildings" will spawn the respective units every so often (haven't developed spawn rate but probably between every 4-10 turns). Aluminum, of course, will be required within city radius to build the Aircraft Mfg Plant. so this limits the number of cities in US that can build these "contract buildings". Mfg Plant is only buildable with the Industry resource. so in the end, there are 3, 4, or 5 spots on map in US with Aluminum.
land based american bombers : heavies in continental US and the mediums and strike with Imperialism. B17 and B24 will be able to be built (and not spawned) but only in US. B29 and B36 will be spawned via "contract buildings", same building sequence, will require Aircraft Mfg Plant etc.
cv fighters : exclusively a Pacific Islands build. always had issues with getting AI to 'replenish' its carrier forces. so here goes with a cheap price tag.
torpedo bombers & dive bombers : same as cv fighters
the Japanese air lineup and build availability differs some from the US and its enemies. in almost all instances, Aluminum & Oil will be required in order to build the non-naval aircraft. iow, the army air force will require resources in order to sustain and replenish. sounds reasonable for the japanese position imo. after all, the quest for resources was the impetus for their east asia sphere push.
so Japanese land based fighters will be able to be built in areas that have access to both Aluminum and Oil. there are plenty of spots on the map where this is present. so at the beginning at least, Japan will have some spots to grow their army air force.
don't be misled by the name 'land based bombers' for the Japanese. this list includes naval aircraft but their land based models. so they were rolled in with the army types. Pacific Islands will be for the naval ones and the Alum/Oil combo for army types. the what-if G10 will be spawned.
all the Zero models will require the PacIslands resource. same for their torpedo and dive bombers.
not sure yet how to handle the Commonwealth air builds, whether to set them in a model that is like the US one (based off of the 3 map regions) or to go with a Japanese model (requiring the Alum/Oil combo). the spreadsheet shots show the US model but not sold on it yet for them.
hope this spells out how the air units will be presented in our little project
