I think you're misunderstanding the math. Calibrated airspeed is the speed we use for control because it's the effective fluid speed. This changes as a function of altitude, as well as temperature and sea-level barometric pressure. So the factor is only ==1 at sealevel. If you are assuming that you're flying higher than sea level, then it's easy to take this into account. You are simulating altitude, right?

I've already told you where to get the equations from. Copy-paste and assume standard temperature and pressure, and this problem is gone.