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Old 01-18-2009, 02:23 AM
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Mark II Mark II is offline
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Originally Posted by CenturiGuy
Here's how the aforementioned Bruce S. Levison did it in RockSim 7 (see attached file originally downloaded from The Rocketry Forum [TRF]). He did it to contrast how inaccurate RockSim 8 was with its tube fin calculations.

Of course, now that I look at it, I realize *I* may have been misinterpreting the way Bruce models tube fins. On the other hand, I think I have *ring* fins down okay, since Bruce was kind enough to look over an early version of my Tau Zero design and tweak it so it actually worked.


OK, Bruce Levison's RS8 version looks almost identical to mine, yet his version works (at least for BP A's and B's) and mine doesn't. I don't see what the critical difference is. Can anyone point out what I am missing?

I encountered this same problem when I tried to simulate a Quest Totally Tubular. That's what caused me to think that there was something very odd about the way that RS does tube fins.

BTW, what are those extra fin-like structures in the tubes in the RS 7 version of Bruce's file? What the heck is that all about? And what is that blue star-like structure at the base of the main BT in your file?

Finally, you mention ring fins. Does RS do something weird with them, too? (See next post.)

I like RockSim's concept, its execution and its polish. I want to keep this on topic and find answers about these particular things, in order to gain some insight and learn a trick or two or a tip that I can use in the future.

If Scott creates a new subsection under the Workbench as James and Jay propose, then I'd be happy to confine the discussion of this one issue to one particular thread within it. That would work well, I think.

I think that the proposed subsection should be confined to talking about specific techniques, solving specific problems and answering specific questions. IOW, "hands-on" stuff. (Conceptual ranting about the program itself or anything else, which I am as prone to doing as anyone else, could still be done in other places, just not there. )

Mark \\.
Mark S. Kulka NAR #86134 L1,_ASTRE #471_Adirondack Mountains, NY
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