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Old 11-28-2011, 07:38 PM
VonMises VonMises is offline
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Default Velocity / Acceleration / Stability Calculations

What’s the formula for calculating minimum velocity for stability, and the distance required to reach that velocity?
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Old 11-28-2011, 08:02 PM
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A common rule of thumb is thrust five times the liftoff weight (mass.)


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Old 11-29-2011, 12:57 PM
shockwaveriderz shockwaveriderz is offline
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Estes TR-10 has some equations that may help to determine this at http://www.oldrocketplans.com/publications.htm#TR-10 page 35 .

You are going to need to determine altitude as a function of time and velocity as a function of time and thrust as a function of time ( I think). I think SmartSim in RockSim can calculate this value but it obviously doesn't provide you with the equations that it uses to do so.



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Old 11-29-2011, 02:20 PM
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this page is a good source
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Old 11-29-2011, 07:13 PM
VonMises VonMises is offline
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Thanks everyone.
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Old 11-30-2011, 01:02 PM
DGLand DGLand is offline
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Quote:
Originally Posted by VonMises
What’s the formula for calculating minimum velocity for stability, and the distance required to reach that velocity?


I posted a whole bunch of info over on TRF about how to model the flight performance; check:

http://www.rocketryforum.com/showthread.php?t=22871

If you want me to step you through my calculations, I would be happy to help you either here, or using PMs, or by email. I hope some bit of all that stuff helps.

The calculation would be much more simple if the motor produced one constant level of thrust for the entire burn, but when you select almost any motor under the sun the detailed thrust curve will be different. Starting right there, you are pretty much required to switch over to some form of simulation or mathematical modeling. You will still be using all the same basic physics eqns but at a micro-time scale instead of as a simplistic overall math problem.
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Old 11-30-2011, 07:03 PM
VonMises VonMises is offline
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Thanks,

Last edited by VonMises : 04-21-2013 at 12:15 PM.
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