Ive been wondering a lot on this but how do you check stability in a large rocket. i know in model rocketry there's always the swing test and things like that but how to you check stability on a rocket that is too big to be able to do that
Most Kits will have A Rocksim or OpenRocket simulator file that provides this information..
Don't use a rope, you will throw our your rotator cuff.
I use a saw horse.
You train the horse to trot in a circle whilst reciting "The Jabberwocky." If the rope vibrates like the gyre and gimble in the wabe, your borrogroves are not mimsy. This is of utmost concern, as if they're not mimsy, then, by default, they're outgrabe, which means the rocket cannot fly in that configuration, of course. The mome raths have to be outgrabe... never the borrogroves.
Later!
--Coop
that's good for the CP. for thr CG, I hang the rocket with a rope making a loop around the rocket on the ceilling of my shop , I slide the rope until the rocket is in balance. I do it also hang to the canopy on the field.
Big thing I would say is trust the CP calculation, but not CG.
I measure the CG by basically balancing the completed rocket on a simple balancing beam (less the motor) and then input that number into Open Rocket.
So here's a question - say my stability is great than 1.0 with no motor but when I select a certain motor, the stability drops to 0.6. Would you add nose weight?
Absolutely. 0.6 is an unstable rocket. If nose weight is impossible in the given situation, go with a smaller motor.
I mark my CP with a piece of tape, and then for each motor, I rebalance it and mark my CG. If it isn't 1 to 1.5 cal., then some adjustment needs to be made.
Depends. My Minie-Maggs, for example, are close to 0.6 with most motors, and stable. But there's a fair amount of base drag on them and other rockets similarly-configured (i.e: short, fat).
Later!
--Coop
Build a smaller scale model and do flight tests.
A rocket scientist would find a work-around for that.CG won't be the same. Seven-foot long rocket with a 54mm MMT won't balance the same as a seven-inch long rocket with an 18mm MMT. CP will be the same if it is scale, but CG won't.
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