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Old 03-06-2011, 10:43 AM
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CPMcGraw CPMcGraw is offline
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Join Date: Mar 2005
Location: Mobile, Alabama
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Quote:
Originally Posted by snaquin
Craig you may want to check the design files I posted when you have a moment. Dv's sure look consistent and low for ALL flights.

Not sure if the two parachutes in the design are throwing it off but just doesn't look correct to me. I can't see how that could make a difference and I checked the settings and both chutes show to deploy at apogee. It was late last night so I didn't run multiples flight profiles.

Let me know if something looks off to you.

.


I got very different results, Steve. Not sure if our starting conditions are similar, but here's what I got on the single-engine version:


B4-4......Alt 275' - 291'......Dv 11 FPS - 23 FPS
B6-4......Alt 290' - 300'......Dv 8 FPS - 18 FPS
C6-5......Alt 642' - 688'......Dv 19 FPS - 39 FPS


Best engine for low Dv is the B6-4.

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For the two-engine version, I get the following results:


A8-3......Alt 270' - 275'........Dv 3 FPS - 10 FPS
B4-4......Alt 594' - 607'........Dv 7 FPS - 19 FPS
B6-4......Alt 603' - 614'........Dv 7 FPS - 17 FPS
C6-5......Alt 1168' - 1199'......Dv 12 FPS - 29 FPS


Best engines for low Dv are the A8-3 and B6-4.

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I ran 10 simulations for each engine. All engines reached safe flight V from a standard 36" x 1/8" rod.
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