My fellow modders and I are creating a mod for Hearts of Iron IV that besides other features tries to get as close to historical WW2 production numbers as possible. For tanks this has been rather easy, and the same is true for ships and other equipment like rifles or artillery pieces. We largely rely on the publications of Paul Kennedy and Mark Harrison, who even replied to our emails and helped us tremendously.
Now we are beginning our work on the various aircraft and we quickly came to the realization that while we have quite accurate numbers for the monetary production costs, overall production capacity and output, we don't have any actual manhour statistics. That is quite contrary to what we encountered with especially tanks, but also more or less any other equipment. This seems to only impact planes which is kind of surprising. It also makes it almost impossible to smack a number on a single plane and call it "production cost/time".
Now the question is, is this just an oversight on our end and have we just failed to find the proper source yet? Which would be not too surprising since we are all amateurs, but on the other hand we are all experienced with online archive research. I have found around a dozen papers on the Luftwaffes production numbers for WW2, why it failed yadayada...but none of the papers mentioned any exact numbers how long it took to produce a plane of any kind, how many people were necessary for it or anything like that. Finding such information for something like the T-34, the M4 or the Tiger is pretty easy in comparison. So why is that, and does anyone here actually know one or multiple sources?
You might find something useful to you in these works if you haven't already looked into them:
Klein, Maury "A Call to Arms: Mobilizing America for World War Two"
Tooze, Adam "The Wages of Destruction: The Making and Breaking of the Nazi Economy"
But I don't remember a specific breakdown in man hours per aircraft for either work. Possibly the British Ministry of Aircraft production may have some statistics in their archives that'd be useful, since they did a lot of coordination of British efforts during WWII. You may also find it worthwhile reading thru the U.S. Strategic Bombing Survey and seeing if there are any statistics in there on German Aircraft production that you can use.
One practice that may make the labor calculations a lot harder than it is for ships and ground vehicles is the widespread practice of subcontracting and subassembly in the Aircraft industry. So you can't just take the output of a big aircraft plant like say, Willow Run, and divide the number of planes that come out by the number of labor hours put in at the plant, because a lot of the aircraft components arrive at Willow run already assembled.
I know in a general sort of way that the number of hours it took to produce a plane fell during the war in most countries and manufacturing processes became more efficient, which is another difficulty.
Anyways, best of luck to you, but I suppose you'll have to fudge it a bit unless you get lucky on a wartime or postwar study. In the rush to make the war economy work ASAP, organizations didn't always stop to compile accurate statistics on costs and labor hours.