Bending the thread a bit to insert a related video that "makes me think".
This is an archive documentary about the making of the Rolls-Royce Merlin engine - not least the tremendous national effort that was required for volume production.
I find it very interesting on several levels:
1. The pipe smoking draughtsmen, the tool shop chappies and the blueprint girls. RR produced over 50 variants of the Merlin, each one which had to be conceived, designed, calculated, prototyped, drawn up and then production engineered;
2. The selection and stockpiling of materials, particularly high grade steels and alloys. Somehow they kept on top of materials QC, and the Ministry of Supply ran a fine balance of allocating these materials to all the demanding arms productions lines;
3. The induction and training of thousands of ordinary men and women to become skilled engineering workers, plus of course their housing, rationing, transport and welfare;
4. The reality of mass war production, particularly in the way that modern obersevers often can't grasp the context. I.e. historians might go "this engine/gun was better than that engine/gun; why didn't they switch to the latter?". Well, this film demonstrates that, iof you want 100k aero engines, you have to choose early and then get on with it!;
5. My grandfather is somewhere in the film, one of the young RR engineers tasked with training new workers and overseeing the QC of sub-contractors and satellite plants. He had to spend weeks away on the job, whilst his wife and three young children were under constant bombing attacks back home near RR Derby.