On Wed, May 21, 2008 at 12:16 PM, Onno Meyer <[EMAIL PROTECTED]> wrote: >> Another failing of GURPS Vehicles mixed TL stuff. > > Yes, but ... > >> Nobody with access >> to TL8 tech builds a TL 6 boat. Even where they're building basically >> a TL6 boat, there are things you'd use from higher TL. A TL 8 prop >> would improve performance -- and it's no more expensive than a TL6 >> one, as the difference is shape, not manufacturing process or >> material. It can be green sand cast iron from a wooden mold, just >> like a TL6 one. You just need the right mold. > > That makes the mold TL8, right? >
Not really. To make a piece of cast iron, the usual method is to take a pattern, bury it in green sand (which is just sand, with some oil or water in it, so it holds its shape), pack the sand around the pattern, remove the pattern, and pour molten iron into the void. For complicated shapes, mulitple piece molds and sand forms can be used. For copying a simple shape in small volume (one to tens of copies, say) it's not unusual to use the actual thing you're copying as the pattern. For higher volume, or where you're making something for the first time, you make a pattern out of wood, or other suitable material. Propellers have improved by quite a lot in the last 50 years or so. Some of that is material improvements, but most of it is better understanding of the aerodynamics involved. The exact shape of the foils on the prop, its pitch, the speed it's normally going to be operated at all mater a great deal. That process lends itself to high-powered engineering analysis and computer simulation, so it's TL8. But once you've got the drawing, making the thing, including the patterns, is just the same as anything else. There's actually a whole lot of products where the manufacturing is lower tech than the design. And lots more where, if you had some reason to want to make the stuff out of obsolete material and with obsolete methods, modern engineering and design would make a better product. much of this is below the resolution of GURPS, of course. -- David Scheidt [EMAIL PROTECTED] _______________________________________________ GurpsNet-L mailing list <[email protected]> http://mail.sjgames.com/mailman/listinfo/gurpsnet-l
