ok, i'm caught up and now know what this thread is all about. Good luck Mike!
I was going to post a few of my recent calcs on airframes and engines etc in the war room but will throw them up here instead. Mike, I hope you convert your modern ships to IJN use and don't waste them on hauling resources!
On airframe and engine research. I won't waste time trying to convince anyone what model of each type of plane to build, but to figure out how many airframes of each type I first figured out the peak demand of each to fill out the existing and arriving sentai/chutai. You then need to select a replacement rate. I chose 1/5th (20%) for fighters and 1/8th (12.5%) for everything else. Yet to be tested in anger.
Then once you select your models to meet the production rate you can set your factories for build and research. I also went heavy on fighter research but went a single research factory on certain types that I want to build and they come just before standard arrival, and start building at 30/month on day 1. I think GA does this and I agree as it avoids you having to spend supply again changing the factory later. There are definite diminishing returns on research factories once you get > 10ish. Each additional factory above about 12 might save you a few weeks, but not months of research time.
Your engine demand can then be calculated. Engine factories are one thing I steadily increase just-in-time to keep up with aircraft production. Surprisingly, I found that the 500+ engine pool bonus only applies to a few engine types and sometimes only for a few months. Some months it will only be partial assistance to your research factories, but it all helps.
I'll throw up the aircraft demand graphs separately and it shows that you need to at least have a plan to seriously ramp up production of aircraft and engines to be able to fill your mid and later war arrivals as the demand for some types hits like a tsunami. I've plotted out Plan A for this so I have something to adjust as the in-game situation onfolds.
I have also just done some calcs on what setting all of this up in the first month or two does to supply, and that did make me adjust a few things. My model suggests you can be aggressive and set most things up in the first few months. By doing that, supply is tight for 2-3 months so no export from Japan, hold off an anything else but building a few key Ports for resource/oil movement, but my choices show that by Mar 42 I'll be well into supply surplus at home again and all my aircraft factories will already be set up with research pumping. Same for initial research factory changes to 0(30) each.
I then modelled engine factory changes to keep pace with the aircraft demand for the entire war, and engine factories need to be steadily increased over time. Once an early engine factory isn't needed anymore it converts to a later war engine and expands steadily again to feed the demand for the modern planes.
I then modelled HI demand for all industry expansion and manufacturing for the duration and tweaked a few other things to avoid HI going into the negative. The HI pool never gets into the multi-millions. To enable my aggressive aircraft/engine program I had to give up on a bit of the naval shipyard expansion that I would have liked, but that was it. Everything links to everything else!
I'll also throw up the HI pool graph to show how it looks and interestingly the critical point was some time in late 44 when pilot training ramps up and manufacturing is high everywhere, with limited numbers of research facilities left apart from the late war models. Once naval and merchant shipyards start ramping down from late 44 the HI pools start to build again. I'll throw up a few graphs to spark some discussion, but I am planning to produce pretty high numbers of fighters through all phases to try and maintain air superiority. I don't care if I slightly over-produce early (Oscar/Zero, not Nate!) and mid-war fighters as when I finally get to test this on a human opponent I am expecting that they will have read something like an obvert vs lowpe AAR and will be aggressive allied early, so if anything I will have still undercooked my early fighter production. These graphs are for Scenario 1, generally based on the # of things needed to fill the groups by type as they arrive except for my FP expansion plan for ASW.
This graph shows the # of aircraft required on map to fill out your IJN afloat air groups (Kido Butai + FP units on ships).
To translate this into how many aircraft factories, apply your own replacement rate:
