06-06-2005, 12:27 AM
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Out To Launch
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Join Date: Mar 2005
Location: Ottawa, Ohio
Posts: 281
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Quote:
Originally Posted by CPMcGraw
In the simulation drawing, I used a 6" motor mount, but installed the motor block at 3.5" from the rear of the tube.
The E15-7 is one of the motors I used in the list. The simulator hit 1518', and reached speed at 36.25". Still needs the 48" rod.
Best altitude was with the F24-7, with 1719'. Speed was reached at 27.2", meaning you can squeak by with a 36" rod here. I'd still use the 48" rod for the additional speed before free-flight.
Craig McGraw
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Hmm.. I noticed on a couple of my D12 flights that my previous 'Roc seemed to "hang" momentarily just off the rod. I wonder if rockets like this and the Mean Machine may actually have such long moments on their CG that they have a bit of "inertial stability" that resists changing direction even if they haven't quite reached aerodynamic stablility off the rod. Not that I wouldn't use a 48" rod just to be safe, but wonder what your thoughts are on this.
The reason I started considering this idea in the first place is because the Thunder Roc would be easy to see at higher altitudes, with a better chance of recovery. Still, a calm day is a must if it's going to 1500'. I went with dual 18" chutes on the last one and never broke a fin, though I DID walk a quarter mile to recover one day with 10 MPH winds. (Where's the emoticon for "exhausted"?)
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John Lance Ladd
Yoyodyne Propulsion Systems
Grovers Mill, NJ
Established 1938
lladd.netau.net
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