MarkH
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M3700
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Zebedee
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What kind of velocity are you hitting? I've had cases where OR predicts a rocket going unstable at high mach and chops off the altitude. A tailcone usually moves the CP forward which can introduce that effect.
RASAero usually gives you a higher stability (and I've seen threads where it's been stated that trusting RASAero stability resulted in a shread in real life) so may not be impacted in the same way.
It's interesting that it thinks the shorter but narrower tailcone is so much better - what did you have entered for your Nozzle exit diameter?
RASAero usually gives you a higher stability (and I've seen threads where it's been stated that trusting RASAero stability resulted in a shread in real life) so may not be impacted in the same way.
It's interesting that it thinks the shorter but narrower tailcone is so much better - what did you have entered for your Nozzle exit diameter?
CarVac
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OpenRocket's lower altitude estimation actually comes from coning showing up in the simulation. Bare Necessities did behave very much like the OR simulation, which gave a very low altitude which we initially attributed to bad simulation. That one went to a static margin of exactly 0. However, after the flight, I looked at the simulation again and the angle of attack went pretty high, and the rocket was rotating around much like the actual flight, causing the reduced altitude in the simulation (~20,000 feet, versus the expected 90k-100k).
If you're getting negative stability in OpenRocket, then I would adjust the design until the simulation flies properly.
Regarding RASAero's tailcone optimism: I tried to do an experiment regarding that, but both rockets had issues with deploying the main for some reason... Someday I will do it better.
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