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Old 09-23-2007, 10:35 AM
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CPMcGraw CPMcGraw is offline
Join Date: Mar 2005
Location: Mobile, Alabama
Posts: 5,357
Exclamation New Plan -- Dead Ringer

Originally Posted by Bohica
I have no idea. I am not a RockSim user...

Main body tube = T-50 @ 18"
Nose Cone: PNC 50
1st ring: CR5060
2nd ring: CR5070
3rd and 4th rings: CR5080
13mm mount
Streamer recovery.
No nose weight required.
Stable and able from 1/2A to A10.



I worked up a simulation of Dead Ringer, using an invisible paper transition with no mass and no CG to simulate our suspicions about how the rings work. The components are not exactly as in your design, but they should be close.

Nose Cone: BNC-50K
Body Tube: BT-50
Ring 1: CR-5060, 3.50" from rear
Ring 2: CR-5070, 1.75" from rear
Ring 3: CR-5080, 0.63" from rear
Ring 4: CR-5080, 0.10" from rear
EM-59 motor mount (SEMROC package)
12" Parachute (or 2x20 streamer)
SE-10 screw eye
Snap Links
SC-24 elastic
SCK-24 Kevlar

Length: 22.35"
Diameter: 0.976" (BT-50)
Span: ~2.80"
Weight: 1.16 oz

1/2 A3-2T......90'......Dv 2 FPS.......requires 25" of guide length
A10-3T........215'......Dv 10 FPS......requires 20" of guide length

Margin with A10-3T motor installed: 2.29 (VERY STABLE!)
Margin with 1/2A3-2T motor installed: 2.08 (VERY STABLE)

CG with A10-3T: 15.54" from NC tip
CG with 1/2A3-2T: 15.75" from NC tip

Let me know if this comes close to your observed performance with the prototype.
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Attached Files
File Type: rkt Dead Ringer.rkt (48.6 KB, 86 views)
Craig McGraw

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