04-26-2010, 11:04 PM
Incurable SEMROC Fan
Join Date: Mar 2005
Location: Twin Falls, Idaho, USA
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.
"Centuri Guy"/"Tau Zero"
YORF Member 28
Semroc SAM #0029
"Your lightyears may vary."
“Centuri fret buzz in an updated form.”
Bill “Wallyum” Eichelberger re: Estes Flutter-By
03 Sept 2014