Since we are nice and calm now and I had a bit of time at hand, I think there are few informations about VRS, that might be interesting to some of you.
First, ONERA with Pierre-Marie Basset et.all did a research paper on VRS in 2006 for a better prediction of the VRS boundary with flight tests and everything.
One of their findings with flight test data.VH: rotorcraft horizontal velocity
Vih: rotor-induced velocity
Vz: vertical speed
The important thing to take away from this is, when you reach a vertical speed (no forward speed) of about 1.5 the rotor induced velocity, you are out of VRS (no more big vortices). In fact, now it is an autorotative decent and the rotor does get energy from the inflow. You may still call that deep VRS, for what I care, but the thingy with the eddies is over. Depending on the experiment, or helicopter, the boundary changes. But -2 is probably a good rule of thumb.
What is different from your normal autorotation, is that the AOA on the blade is much higher and therefore the driving region is smaller, but the stalled and driven regions are larger. Which explains nicely, why you have so little control in certain helicopters. That the whole thing is not very smooth comes from the fact, that there is still a lot of turbulence hitting the rotor and produced by it. But VRS is gone.
What is also remarkable, Vz stabilises at the VRS boundary. At least for me, that explains, why for the love of god I never could get the R22 descend more than around 2000 ft/min during demos.
This has been know for a long time as the vertical wind tunnel experiments of NASA have shown the same. Or Prouty.
The thing that I find a bit more interesting, is a paper from the Naval Postgraduate School by Rumsey from 2003 about the Vortex Ring State in a water tunnel.
Here is the blade bending load:
H-34 Flapwise Bending Moment At R/R=0.575
That is really hard on the components and while it is positif over the tail boom, it is negative at a substantial part of the disc.
There you have it. At a certain Vz, VRS is gone, deep VRS is in reality an autorotation and the flapping in VRS is quite erratic.