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Old 10-04-2011, 01:24 PM
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jharding58 jharding58 is offline
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I think that there may be a little more getting worked up than is needed over a piece of software that is after all designed for the hobbyist. Getting in to the more robust capabilities of RS-Pro I would expect a high order simulation of launch charactersitics and design considerations. With more esoteric creations it is a given that at some point you will reach the limitations of the software's abillity to accurately model. In the case of the Stovepipe for example, being a tractor design the CG cannot help but move aft during the flight reducing stability. I seriously doubt that Rocksim takes into consideration the effect of burn on motor mass (although I could certainly be wrong) and the translation aft of the CG. Again with the Stovepipe the CG and CP are so close coupled that stability would be difficult to accurately predict. Also the Reynolds numbers of components this small are very hard to model, although I am relatively sure that RS does not embark down that path.

Between the RockSim and Barrowman equations there is a high order of predictability in the ability to define a model, plot the characteristics of the proposed model in flight, and render a predictable confidence of stability and success in flight. I agree completely that there needs to be a balance in terms of reliance upon modelling and mingling of experience and instinct in the operations of any software (given that there is not a computer in the world which multiplies), but from the 99 percentile perspective RockSim provides a reasonable modelling modality without the effort and expense of producing and testing an artifact.
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