When do you learn that your scientists have mastered the design and manufacture heavier than air aircraft? Its 1917 in my game as Japan, and I have been able to build air bases, but whenever I attempt to request proposals for aircraft, no aircraft roles appear on the drop down menu to choose from. Is this usual? Will I get a very specific message such as "my scientists have mastered flying boats" before I can actually procure any?
I think it may be possible for key researches to be delayed and thus get things like airbases without planes.
There should be a research like "torpedo planes" or "airborne tropedoes" which unlocks the torp bomber. I know in one game I had lots of delays to get the air dropped bombs to the point I was designing bomb capable ships but they never actually bombed things in the battle map even if on an strike mission.
So I discovered as I kept playing. I had airbases and seaplane carriers before I finally got the magic notices that our scientists had mastered any airplanes I could procure to buy...and then I was inundated with private companies wanting to sell me planes. I was also playing with the "slow aviation development" option selected, which is also probably is why I kept wondering why we didn't invent any airplanes until well into the late 1920's. It does seem a bit out of order to be able to build and develop air bases and seaplane carriers before you actually have the airplanes to use on them. But as it was I enjoyed the overall effect of the "slow aviation" option. When the game ended in 1955, CVs were still outnumbered by BBs and BCs in most navies, and (except for scouting) they were never a factor in any war I fought in the 1940's and 1950's. As a BB guy, I rather liked that.