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Old 01-17-2007, 05:32 PM
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CPMcGraw CPMcGraw is offline
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Join Date: Mar 2005
Location: Mobile, Alabama
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Exclamation Revised Plan -- Andromeda Mk VI

The Andromeda has been a work-in-progress for some time, now, and I hope you don't mind the constant revisions. Discovering the issue with the ring fins and simple inside tubes didn't help, but at least I have a better understanding of what to expect in future designs with this detail. Now, as I look more at the last-posted version (Mk V.2) I see the need to "dress it up" just a bit. So with that, I give this additional caveat: These details add visually to the design, but they also kill about 150' off the top altitude with the C6. I don't think it's the weight as much as it is the negative stability this detail works against the static margin when applied to the forward shroud, and what I had to do on the rear shroud to compensate. Visually, these details make sense...

Length: 27.95"
Diameter: 1.64" (ST-16 shrouds)
Fin Span: 5.799"
Weight: 2.022 oz

CG: 19.5362" [empty location]
CP: 22.8574"

B4-4......316'......Dv 16 FPS
B6-4......324'......Dv 12 FPS
C6-5......756'......Dv 7 FPS

All motors in this list reach flight velocity on a standard launch rod. The A8-3 had poor overall performance and required a longer rod, so it was dropped.

Enjoy!

Addendum: As with all the other issues in RockSim, I think this detail issue is over-calculated by the program. These shroud details should never have caused as much instability as shown. The problem is these items had to be created as FINS, and not as raised surface items, which probably would not affect the flow of air to the same degree. I am sure, with more research into the program, I can compensate for the extreme effects. I really need to pull out those older "Peak Of Flight" newsletters and rummage through them for anything on fins...
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