Calculation method in RockSim: RockSim versus Barrowman equations

[MetricRocketeer]

Hi everyone,

I have asked a few people whose judgment I trust as to whether to use the RockSim or the Barrowman stability equations when using RockSim. I think that I have always gotten the answer to use the RockSim equations, which as I am sure you know indicate greater stability.

I would just like to nail this down. Should you ever use the Barrowman equations? Why or why not?

This is an open-ended question, but I would be curious to see the feedback from this community of rocket experts.

Thank you.

Stanley

 

[mikec]

I did a fair amount of research on this several years ago. The Rocksim equations are less conservative than Barrowman and it was unclear they were well-motivated. I use Openrocket and Openrocket only implements standard Barrowman. My advice is to use the Rocksim equation only at your own risk.

That said, all of these simple stability equations are at best approximations for near-zero angles of attack and don't capture the full physics.

 

[SpaceManMat]

Are you are cutting the stability so fine that you need to second guess the simulation?
You should be aware that the static stability of RS/OR does not give you the full picture,. While static stability is generally ok for lpr, you need to look at stability vs time for a simulation that is close to a stability of 1 or for a supersonic flight (most in particular there are some dramatic changes to CP in the Mach 1.5 - 2 range). This goes for OR, RS or Ras Areo. I would not use RS for supersonic it does not do as well there.

 

[Bat-mite]

I would want to err on the side of being overstable.