#1
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Starlight
The Starlight is online now.
Sheryl@semroc |
#3
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Quote:
Bring some to NARAM, I want one!
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"I'm a sandman. I've never killed anyone. I terminate runners when their time is up." Logan from "Logan's Run" http://sandmandecals.com/ |
#4
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Hmm. The photo or artwork is not showing up for me.
Next order will have to include it. Man, I have a backlog to build down.
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Retro-grouch |
#5
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Order in ----- Hehehehehehehehe...this is so cool
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Dumpster Diver |
#6
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Quote:
My order is in also. I loaded the RockSim file into OpenRocket and found that I needed to increase the nose weight from .2 oz to .7 oz to get a the rocket to show as stable (Cal => 1.0) when any engines were installed. Is this because OpenRocket does not understand the Rings?.. or should I trust it and add the extra weight?
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Member: Washington Aerospace Club NAR Section #578 NAR #94383 TRA #15009 HPR Level 2 Last edited by Right Wing Wacko : 07-07-2012 at 09:48 PM. |
#7
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I'd trust Semroc. I don't think they'd sell you an unstable rocket.
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Retro-grouch |
#8
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The Starlight is another old design that was probably marginal at the time. With no nose weight, Rocksim gave a margin of .54 using a C6-5 and a margin of 1.27 with the added .2 oz. weight. I never saw a Starlight back then that was unstable, but we still added the weight for margin in our release.
I have been trying OpenRocket on our designs and the results are always more conservative. I do not know where the differences are. We always select Rocksim stability equations instead of Barrowman equations for stability calculations. Perhaps OpenRocket uses the older, less accurate equations. Probably half of our kits would be marginal or unstable if we used Barrowman, yet they clearly are not. (Well the Mars Lander is clearly marginal and should never have been released. )
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Carl McLawhorn NAR#4717 L2 semroc.com |
#9
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Semroc Groonies: *Marginally* stable?
Quote:
Empty -- 1.15 calibers A8-3 -- 0.78 marginal B6-4 -- 0.75 marginal C6-5 -- 0.68 marginal But you *say* it flies okay "in the real world?" It makes me want to push that motor mount back until the engine hook lines up with the main body tube, instead of having it recessed. Just sayin'. .
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Jay Goemmer "Centuri Guy"/"Tau Zero" YORF Member 28 Semroc SAM #0029 NAR 86131 "I think about organizing things all the time. Never seems to happen. I find something that piques my interest and I'm off on a quest. Or a Centuri. " --Bill Eichelberger, 02/22/2022 “Centuri fret buzz in an updated form.” Bill “Wallyum” Eichelberger re: Estes Flutter-By 03 Sept 2014 |
#10
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The Goonies and Groonies are all "short, squat" designs that somehow get "aerodynamic exemptions" from the one caliber rule. I have heard of people changing the engine mount in the old Goonies from 13mm to 18mm, not adding nose weight and having stable flights. Rocksim shows that to be impossible.
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Carl McLawhorn NAR#4717 L2 semroc.com |
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