04-01-2009, 11:38 AM
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BARCLONE Rocketry
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Join Date: Mar 2005
Location: Mobile, Alabama
Posts: 5,357
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Quote:
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Originally Posted by jetlag
But a D12-5 is not on the list of recommended motors (Idon't have RS 9)
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The D12-5 was used in the simulation runs, but it should have been the D12-3. Even so, the problem isn't the time delay. It's the static margin. With no engine loaded, the model only has a margin of 1.49. When you add the D12-3, it falls to 0.69, which is below the minimum of 1.00 (one body tube diameter between the CG and the CP).
The point is this, if the static margin is that low on just a D12, how low will it be on the larger engines? What this brings up is a question of how accurate the RockSim calculations are, since it's obvious Apogee and Shrox have working prototypes of this design. |