I'd be interested to find out just what flight phenomina is experienced in the famous 8,000 feet descents, but for my money it is not a sustained system of rotor tip vortices. I mean, fair suck of the sav guys, how on earth could those vortices withstand the force of the uprushing relative airflow from directly beneath?
Perhaps it may have been stalled rotor airfoils, something which occupies my imagination a bit, whilst I am demonstrating the maneuvre.
In all the thousands of times that i have done it, in both '47's and R22's, the aircraft will accelerate very quickly and fall vertically but never more than 200 feet at the outside. The altimeter is the only guide, it will all of a sudden show the height lost in one gulp just after the rotors hit clean air and the aircraft slows the descent appreciably.
Usually one can control the exit as one must as if one stuffs up and inadvertantly encouters VRS, it willusually only drop about 80 feet, so remember, if you enter at fifty feet or less it will only ever be the last 30 feet that will hurt.
i disagree that one cannot control the A/C attitude in the vortex state, as the rotor blade is still flying and generating lift in the cocoon of vortices. duh - that is how the vortices are being generated. so use that control to tilt the rotor disc and then it will simply "slice out' of the cocoon of vortex ring, which was attached to the disc.
(and yes also lower the collective A of A if possible, which should also stop the generation of vortex, but I would never roll off throttle with the collective still up, sacre bleu, there would be two of the perfect conditions for rotor blade stall)
similarly when I tried to hold the aircraft upright, the it always fell to the heavy side, with the same slice out effect effect, that is with only the pilot on board of course, remembering that the 'cocoon' that you are in has separated from the surrounding air mass.
demonstrating VRSlearning IVRS and recovery is an absolute must. IVRS is best explained and demonstrated as the commencement of the falling sensation in the pit of the stomach. at that point do something real quick.
as discussed before, jumping it out of the VRS state very early and quickly with collective can be done, but don't go into a state of overpitch by doing so.
the very first time I got caught I did just that. I had descended quickly into a fairly large hole in 60 feet high timber to turn some belligerant cattle, hard and fast like. The ground had been burnt recently and rained upon with a heavy storm straight afterwards, no dust or loose material to show me that the headwind I had on entry was now a tailwind with a just developing willy willy on the starboard side.
i dropped about ten feet and jerked it to stop it at about 2 feet. I had over pitched, I landed carefully and breathed a couple of times before proceeding.
I have no intention of replicating the maneuvre in heavy aircraft, neither do i think it needs to be.
But, if you guys want to argue about a sustained VRS for about 8000 feet, put a bloody smoke generator on your aircraft and film the effect, before going on, please.
Last edited by topendtorque; 29th May 2010 at 09:01.