Originally Posted by
JohnDixson
Number was in the 60% range. So there is some margin between where the qualification test crews operate and the point at which the situation turns really dangerous.
Was that really in a fully developped descent at a high rate?
A transient drop to 60% - 70% (e.g. due to pulling collective while still in Forward flight) while the RoD hasn't built yet is something very different from a constant drop at a high rate of descent. The AOA figures in both cases will be quite different and thus the reaction of the rotor System.
I would be very careful spreading values in the range of 60% as survivable.
For a fully developped descent I have serious doubts. It will depend to some extent on the type of helicopter as well (Disc loading, pitch angle range)