SIMS are only as good as the flight model that supports them-agreed. Real data is hard to come by as there would be few QTP's that would volunteer to collect test data points for this EP real time.
As discussed a knowledge of concepts is required. As for letting the NR get to 70% holy S - - T Bat Man, sounds like a death wish not to mention undervoltage protection kicking in below 85% NR, which now means dealing with the EP with no AFCS, Stabilator, generators and inside indications of actaul rortor speed at this point (unless APU start). At 70% NR the blades fold up do a clap and you glide like the titanic.
Food for thought.
Lasty.
