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Old 04-06-2006, 12:51 AM
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CPMcGraw CPMcGraw is offline
Join Date: Mar 2005
Location: Mobile, Alabama
Posts: 5,357
Exclamation New Plan -- Prowler

Another Schoolyard Sounder...

OK, folks, I know these 3FNC designs are not the most interesting, but there is a purpose behind them. Especially this one, as it again uses that stepped fin shape to reach the lowest Dv possible with a rocket of this shape and weight. Altitude was not a priority, but keeping it stable and getting the softest deployment possible were priorities.

You will notice a full dozen runs on a single motor, which demonstrates the range for the Dv better than a single run. It took me over two hours to tweak the shape to get those low numbers; even the slightest shift in the fin plot points could alter the Dv by as much as 200% from what you see here (or, the Dv's would easily double to 8 and 10 FPS).

Take this one as an academic study in fin shapes and their respective flight characteristics...

Length: 15.0434"
Diameter: 0.908" (ST-8)
Fin Span: 3.2272"
Weight: 0.822 oz

Average range:

A3-4T.....397'.....4.75-to-6.19 FPS Dv.....576.70 FPS/S.....36" Rod

I think it still makes a great flying design, even if it is just 3FNC...

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Craig McGraw

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