A big part of the misunderstanding among rocketeers of how aerodynamic stability actually works is the common use of approximations and "rules of thumb" in general discussion and in both Open Rocket and RockSim software. The assumptions we put into simulation software need to be corrected to the actual numbers once the rocket is finished. This is most easily done by adding a mass object to correct the estimated weight and balance of the simulated rocket match the real rocket. Remember the basic issue with calculations and simulations: Garbage In=Garbage Out What stability ratios are you getting with Open Rocket? Have you weighed your rocket and measured actual CG (always) with the motor you intend to use and compared the simulation to relaity?