RockSim CP Question

[dbrent]

Hey All,
I'm currently putting together my level 1 cert rocket which is a 4" Nike Smoke from Performance Rocketry. I need to find the CP for this rocket and while I do have a RockSim file that someone did for it, it's not an exact match of the way I built my kit.

I beefed up the centering rings and moved the rear ring flush with the end of the motor tube to accomodate a flanged Aeropack retainer... etc.

My question is, does anything other than the out side dimensions of the rocket affect CP? In other words, since I'm a little new to RockSim, I may not get the internals exactly right, but if the external dimensions are accurate, will the CP be the same?

Thanks,
Don

 

[new2hpr]

That's quite a bird for an L1!

Yes, the CP depends on the components exposed to the airstream, so the guts will have no effect.

To correct my Rocksim model to reality, I weigh the final rocket and find the "real" CG, then add a dummy weight object at the right location to make the RS model match. Then after a couple real flights, I can dial in the drag coefficient to bring the sims close to actual performance.

-Ken

 

[dbrent]

That's quite a bird for an L1!

Yes, the CP depends on the components exposed to the airstream, so the guts will have no effect.

To correct my Rocksim model to reality, I weigh the final rocket and find the "real" CG, then add a dummy weight object at the right location to make the RS model match. Then after a couple real flights, I can dial in the drag coefficient to bring the sims close to actual performance.

-Ken

Thanks for the reply!
I actually selected that rocket for it's durability.