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Old 04-26-2010, 11:04 PM
Tau Zero's Avatar
Tau Zero Tau Zero is offline
Incurable SEMROC Fan
Join Date: Mar 2005
Location: Twin Falls, Idaho, USA
Posts: 2,319
Exclamation New Design -- Centuri Scram-Jet 1.37X

As I discovered when I RockSimmed the ST-8 Centuri Chuter-2, sometimes the original designs have *very* high deployment velocities. The Centuri Scram-Jet displayed the same tendencies.

I noticed that when I upscaled the Chuter-2 1.48X to an ST-13, the performance on 18mm motors greatly improved. This led me to conclude that at least some classic designs may have simply been overpowered for given motor sizes.

To that end (and since I can't ever seem to leave well enough alone), I upscaled the Scram-Jet to ST-7 (1.40X) and ST-10 (1.37X) body tubes. I was surprised and pleased to find much better performance figures on standard 18mm motors.

Bill E. "Wallyum" and I have wrestled with making this particular design work in the 21st century *without* ejection charges burning through Kevlar thread. Finally it seems I have a solution: upscale to these dimensions, use 3/32" thick balsa (*not* basswood!), and use 600 lb. Kevlar on an ST-710 18mm motor mount.

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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

Last edited by CenturiGuy : 05-01-2012 at 07:51 PM.
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Old 04-27-2010, 10:52 PM
A Fish Named Wallyum A Fish Named Wallyum is offline
BP Mafia
Join Date: Mar 2005
Location: Ft. Thomas, KY
Posts: 8,642

Loved this design, but I never had any luck with any of the 2? 3? 4? that I built and flew. The last one was the big heartbreaker. It was beautiful when I finished it, then had the Kevlar break on one of the review pic flights. It was a hot day, so we were able to watch the nose cone and parachute thermal away toward Bellevue and the river for quite some time. Heavy sigh.
Bill Eichelberger
NAR 79563

I miss being SAM 0058

Build floor: Estes - Low Boom SST Semroc - Marauder, Shrike, SST Shuttle

In paint: Canaroc - Starfighter Scorpion Centuri - Mini Dactyl Estes - F-22 Air Superiority Fighter, Multi-Roc, Solar Sailer II, Xarconian Cruiser Semroc - Cyber III

Ready to fly: Estes - Solar Sailer II Semroc - Earmark
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Old 12-28-2010, 07:49 PM
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CPMcGraw CPMcGraw is offline
Join Date: Mar 2005
Location: Mobile, Alabama
Posts: 5,357
Default Fin Patterns

One sheet with all fin pieces.
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Craig McGraw

BARCLONE Rocketry --
BARCLONE Blogsite --

BARs helping BARs

SAM 0044
AMA 352635
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