JWE
Posts: 6580
Joined: 7/19/2005 Status: offline
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quote:
ORIGINAL: Tiornu Yes, I think you must be right in that no one was going over rivets with a magnifying glass. However, there were problems matching the hull sections. If this is of sufficient interest, I can try to find a direct quote. I would appreciate it muchly. very interested in this. quote:
ORIGINAL: mikemike This is a bit overstated. The workforce was experienced enough, but low on body count, which slowed construction. They may have been demoralized, but I imagine the Gestapo may have compensated for that. The air threat was considerable, of course, that is why much of the section work was shifted to bunkers. Most section yards escaped being targeted for bombing, anyway, because they had nothing showing on the slips anymore. An interesting detail in this context is that, when sections were assembled, this was done by four welders simultaneously, evenly distributed around the circumference of the hull, and that the welding process was not to be interrupted for any reason, even under air attack. I can certainly understand that. Interruptions cause distortion. A bad thing, iirc. quote:
Sections were, as I've said, designated for specific boats from the start. There wasn't normally any mixing/matching, except when sections were destroyed by bombing. I also don't believe in poorly-made components on a large scale. The section yards were responsible for delivering only sections that were up to specifications, meaning they had to do extra remedial work when supplied with substandard components or the section wouldn't have been accepted by the relevant team of the War Production Ministry. Sections were not misaligned as such on assembly, proper (longitudinal) alignment was very carefully checked by optical measuring methods. However, if the diameters of the sections differed too much, the methods used to adapt the sections to each other might well have weakened the structure. This is the part I’m interested in. You can have two problems with cylindrical section components; lateral distortion out of the bond plane, and diameter mismatch. There’s ways of compensating for both but the integrity of the seams just ain’t quite the same. I would really like to know how they solved this; or did they? quote:
I agree that the Type XXI program would have progressed smoother and faster if the section yards had built the whole section by themselves, but the planning called for building rates that couldn't have been achieved in that way, so some subassembly was farmed out to subcontractors. This is still a risk even today, witness the Boeing 787 troubles. Not just Boeing. pretty common problem in modular shipbuilding today. maybe why everybody has gone to the extrusion method.
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