I'm still wrestling with aircraft production. There are so many different models now. Here's some interesting info that may shed a little light on what to do. This shows a roll up of how the starting air units upgrade. This may be a good planning factor for airframe production (and engine production too). Note that this applies with PDU off. I like to play this way. It's more historical. Here is the IJN. IJA will come shortly.
Edit: This does not include carrier aviation. I don't have all the info to do them yet.
