Aircar I am based in Melbourne and would love to know about the Hawker Demon in your shed - A1-8? Attached pics, if I get it right, are Hawker Demon spar section, with booms formed from high tensile steel strip in an 11 pass strip former. The metallurgy, run through a babelfish from 1930's British Aircraft Standards, is basically US 4140, which you can only seem to find in high pressure gas pipeline material today. All the revheads making tubular racing car frames say they have climbed to the top of the mountain using 4130, which is quite available, but it seems to me that what the aircraft engineers were doing in the 1930's with lightweight 4140 sections was, and still is, exotic, fantastic metallurgy. In a biplane with struts joining wings different parts of the wing spar were subject to greater forces, and this was accomodated by inserting additional sections of tube inside the spar boom, to thicken the section. Sometimes you see old bridges, where a beam section is composed of hot riveted plates, with more plates laid together in stressed sections. These engineers were pushing the boundaries of materials performance, working with exotic new materials while borrowing concepts from the comtemporary age of steam. Another pic shows spar with aluminium ribs attached. There is a fantastic amount of componentry in these wings. I do understand that riveted construction is more reliable in a stressed structure than welding, because I keep reading about welded submarines that leak, work with riveted vibrating quarry screens and fly by preference riveted Boeings. I do also subscribe to the theory that in the 1930s, if an aircraft component could be designed to be manufactured using 10 man hours, it was redesigned to take 50 man hours. I guess that the explicit goal of the German military industrial complex was to employ folk, and it would not have been too much different in the United States. If you put a 1930's design Curtiss Kittyhawk tailplane assembly next to a 1940s North American Mustang tailplane assembly, the manufacturing story has reversed, driven by skilled labour scarcity. I think scarcity drives manufacturing efficiency. The designer of the Mitsubishi Zero, hampered by a lack of high power engines, broke down his design into pieces 1/20,000 of the target weight, and strove to find weight savings in components at this atomised level. He created a fantastic, fearful aircraft that dominated the skies in the Pacific in the first half of the war, but thankfully for Democracy could not survive battle damage or dive after American planes built like warships. The occupation by Japan of most of the global rubber resources in Malaya created a critical problem of scarcity for the Allies in sourcing tyre rubber. I think the greatest manufacturing efficiencies and cost gains came from standardization. Instead of every aircraft or truck having a unique wheel or tyre the Army Navy code (AN) created standard tyres that could be used across a range of aircraft. AN codes covered everything from bolts to oil filters. It took a long time to create and develop a bureacracy to identify these issues and develop solutions. Known reliable engineering solutions such as the Rolls Royce (Packard) Merlin V12 engine, Browning machine gun, Pesco fuel pump and Lockheed (UK) hydraulics were propagated across many aircraft types and manufactured in the UK, US, Canada and Australia. All these standard bits wound up in places with different conditions. With bombs falling on England the 'Shadow factory' was the explicit policy, with numerous, small, dispersed, component manufacturers de risking the system of aircraft manufacture. Even the final assembly of a particular aircraft design was dispersed among a number of factories. It could not grow to the scale of US or Canadian manufacture, but it worked. In the US, free from bomb damage, massive centralised complexes like Boeing, employing thousands, could eventually create colossal scale and efficiency. It is interesting to observe, that when Soviet ICBM could finally reach the US, the Eisenhower administration, via tax breaks, supported the dispersal of American industry. When you drive through some small town in America, and come across a global scale factory making things in the middle of nowhere, it makes no sense until you accomodate this. At least that was the case when I drove through America in the late 90s, when it still made things. No question of manufacturing efficiency can be considered in isolation to the conditions in the environment where the manufacturing occurs. It was the explicit policy of British Bomber command, after failing earlier in the war in accurate, pin point attacks on sensitive manufacturing 'bottlenecks' like ball bearing works, to inconvenience the German worker. It was reasoned that if the German worker could not have a hot cup of tea in the morning or a hot shower after work, or if he could not catch a tram to work, the ball bearing factory would soon fall idle. So basic infrastructure was targetted, most vividly the example of the Rhur Dams, and every day railway locomotives. It worked. Poor old Ferdinand Porsche had to work out of a barn in a forest. You cannot compare the magnificent efficiency of Boeing in Seattle, North American in California or De Havilland in Downsview, Canada without some recognition of the De Havilland worker in Halton in the UK running from a lathe and cowering in a slit trench a lot of the time. Its a wonder that anything was made in wartime Europe at all. War is cruel, but it would have been a fantastic time to be an engineer.