IFMU, settling with power is not vortex ring. It is being unable to arrest a rate of descent due to a lack of power and can occur at rates of descent needed for vortex ring.

For something like an R22 you need about 700fpm to be in the VR area. From a previous post by Nick Lappos:
Nick did have all this on the web, but his site has disappeared.

This:
is from this site on VRS.


I have to agree that it is probably unlikely to get into VR "ridge soaring" due to the horizontal componant of the airflow. However, you are still descending. Not in relation to the ground, but in relation to the air around you.

Strong Updraft
 

Flying quite a bit in Mountainous area's, I regulary get updrafts that are more powerful than the autorotative capacity of the heli.

As TFS described it - not hovering but level- I assume he lowered collective quite a bit to stay level, so entered in full autorot, which will not pass via a VRS-area, because reversal is fast.

Even a few weeks ago I nearly had an overspeed because of trying to maintain altitude and lowering the collective to far. A complicating factor is that the wind streams are turbulent, so with low collective you can still be hit by a stronger updraft, which at this points requires you to pull collective and start climbing to avoid overspeed. It helps to know that there is no solid deck right above you, or strict altitude requirements at this stage....

So imho the sound could have been overspeed


d3

Quick way down
 

Many years ago, flying from Prince George to Vancouver, after leaving the High Arctic, and just north of my planned refuelling stop at Hope, BC, and near the junction of the Thompson and Fraser Rivers, I ran into significant updrafts in a very heavy Alouette II. ::(
After the lever was on the bottom the next move was to push the nose over until near vne. Problem was that I was in a valley with very hard walls and the cloud base at 2500'. With the cloud base approaching - like a couple of hundred feet - wrapped it into a 'very' tight turn. The ROD increased nicely but so did the RRPM. Keeping it in the 'green' made for a VERY Interesting ride.
Now I know why they call the place Hope ! :cool:

The reason you won't get VRS in an updraught by a cliff face/mountain is that the all the air isn't going even close to straight up so you won't have the low IAS required.

The updraught is caused by the horizontal movement of air, that is the air all the way from the bottom to the top of the cliff being forced up and over it, so whilst you may have very low power (even autorotation) due to the vertical component, the horizontal component of the wind at the top of the cliff where you are hovering is going to be too high to give you VRS problems.

This is not the same as descending vertically (or nearly so) in a uniform airmass.

You can get into VRS into air that is moving forewards, backwards, sideways, upwards, downwards, a combination of those five, or stationary. The point is not where the air is moving relative the ground, but how the helicopter is moving relative to the air.

If the helicopter is moving slowly forward and down through the air with power on, then you can approach VRS conditions. To make this happen in an updraft, your airspeed needs to be low, power needs to be applied and you must be moving down through the airmass (not necessarily descending relative to the ground...).

Matthew

I would agree if speed is really low, see different other tracks on that, where it was stated that VRS is very unlikely at any significant speed. A theoretical approximation is a linear relation between (relative, I fully agree with your statement) vertical speed and forward speed.
So FS you remember at what forward speed that was ..?

d3

Matthew, your groundspeed may be low or zero if you are hovering in an updraught but your airspeed is likely to be significant, we are talking winds in the region of 30 kts plus to produce an updraught strong enough to give a low power setting and that 30 kts is blowing across the disc from ahead of you (if you are pointed into wind) while the air blowing against the cliff below you has been deflected upwards. This is my point - you are not simply in a mass of air moving straight up - the rest of the air mass (the bottom of which has hit the cliff and been pushed up) is still blowing in your face. Therefore no VRS as the resultant airflow is nowhere near vertical so the tip vortices (which are less powerful at low AoA) are not recirculated and the root stall doesn't happen, again because AoA is low.

Crab.....

The shape of the terrain and the strength of the wind dictate the direction of the airflow, a vast majority of the time a 30 kt wind on the top of a cliff will still result in a horizontal component to the airflow, on rare occassions it will be a very localized strictly vertical airflow.

It all depends on the shape of the terrain, the strength of the wind and the exact location that you are hovering. You can be in good air with some horizontal flow in one spot....move 40 meters toward or away from the cliff and now the flow is a lot more vertical

Consider.....a 10 knot vertical wind is moving at approximatly 1000 feet per minute.....thats significantly more than what most pundits would say is required for VR never mind 30 kts......

Granted it's a rare occurance for you to happen to be in the exact spot where all these conditions come together and try to nail your ass but it does happen.

I suppose its all a matter of how often you work in the mountains and how much time you spend hovering on the edge of cliffs. The more you do it the more you are likely to eventually hit the sweet spot.

Signed: Dammyneckhurts