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Condition for Vortex Ring

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Condition for Vortex Ring

Old 20th Nov 2017, 16:12
  #21 (permalink)  
 
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How many times are we going to dance around this Maypole?
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Old 20th Nov 2017, 18:54
  #22 (permalink)  
 
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Slightly off topic but interesting and positive use of vortex ring:



Or the vortex ring blower:

Ring Blower

Cheers SLB
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Old 20th Nov 2017, 21:29
  #23 (permalink)  
 
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My question still stands, has anybody see a useful side of VRS?

To Thomas Coupling, I do not know your experience and what you have done in your career and you don't know nothing about mine. Now to answer your comments in the order they have been written, you don't see any useful side of stall and spins, let me tell you this, there is a usefull side to spin and not to long ago it was used on a day to day basis and SAVED a lot of lives. Ask around. You are simply not aware of it.

You say that I probably never experience VRS in my 8000hrs of VertRef, not to sure what you base your info on? But HeliDuck seems to think otherwise for a vertref pilot and he is not the only one.

Always avoidable you are wrong on that one, it shows that you have never done any longline worth talking about and never work in Mountains or at altitude worth talking about.

I said there was a lot of knowledgeable people on this site and I meant it but I never said they were "All knowing beings"

On the subject of VRS, I have found the condition to be very useful on certain occasion and altitude. You see you can get a tremendous rate of descent (if you don't mind the rock&roll ride on the way down) also you get a STEADY rotor RPM all that time, no overspeed, quite handy at High altitude.

Understand there is no malice or intention of it in my writings.
Also understand that everybody has his own experience and done all sort of different things in this industry.

Question still stands, anybody else that have used that condition on purpose to attained a desired result?
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Old 20th Nov 2017, 21:49
  #24 (permalink)  
 
Join Date: May 2008
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Thomas Coupling,
I have worked along side Jacque , believe me he knows what he speaks of. Probably the most impressive experienced 214ST pilot on a longline in the World. Amongst thousands of hours on other mediums/heavies.
I respect your knowledge and experience in all things Mil and HEMS/Police. If you have never done production/precision longline I imagine you wouldn’t know.
Same as Jacque, I have over 8 grand hours on a longline doing production stuff i.e seismic. It is very easy to get into VR.
Just out of interest, how many hrs you got single pilot on mediums doing precision longline 10 hrs a day?
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Old 21st Nov 2017, 01:54
  #25 (permalink)  
 
Join Date: Apr 2017
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VRS is deadly!
Spent many a years coming down the mountain with a dangling load in everything from lights to the big heavies.
Avoidable, yes! Just have to know it is there waiting to bite you. My Canadian Colleagues may disagree me, but personally I witnessed two drivers on same job experience VRS.
There was a reason for it, production!
It can happen anywhere anytime. (If you are not aware and tired)
My "teacher" retired a short time ago. He was in his 70's yes 70's and had over 30k.... said he only experienced it twice because he was not flying the machine it was flying him.
Wise man!
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Old 21st Nov 2017, 08:43
  #26 (permalink)  
 
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Fijdor/Newfie:

I'm going to put your lack of knowledge about this subject down to definition misunderstanding.

And I'm not going to waste any more of my life trying to educate people who haven't thoroughly researched the subject properly.

I can't force you to DYOR.

VRS is a DEVELOPED state. It is a situation where you as the pilot become a passenger. VRS will always end in disaster if there isn't sufficient height between you and the ground. If you have sufficient height - then an attempt at recovery often leads to a successful outcome - but not always.

INCIPIENT vortex ring [IVRS] is what people like you have 'probably' been into (due to your long line work) several times. You have 'probably' noticed the symptoms of the ONSET of VRS (which is IVRS) and responded appropriately, resulting in a fairly rapid and unexciting recovery. Probably within a couple of hundred feet.

Now there are DOZENS of very well discussed conversations on PPRuNe which dive deep into this subject matter. My advice to you two is to find an hour or two and go sit in a quiet corner and research more thoroughly the subject of VRS.

If you are either american or american trained, it is also essential you learn the difference between VRS and Settling with Power (SWP), because for some obtuse and bizarre reason, even your own FAA believe the two, are one and the same

Please find time (even at your level of competency) to research the following:

VRS versus IVRS.

and

VRS versus SWP.

I continue to be amazed by how many so called professional helicopter pilots out there STILL don't understand basic aerodynamic concepts.

Frightening............................
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Old 21st Nov 2017, 14:45
  #27 (permalink)  
 
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I am a Canadian born and raised here, also trained in Canada by an experience pilot/instructor which seem to be out fashion these days (trained by an experience pilot/instructor that is).
In Canada, Transport Canada (our aviation authority here) is well aware of the difference between VRS and SWP and so am I. But you are right that the FAA do not recognize the differences.
So I will bow to your great knowledge of the subject and leave this tread and when I retire in 2 years from now I might take the time to read on VRS, IVRS and SWP and try to understand how I have been able to survive 40 years + doing what I am doing without knowledge of this condition called VRS (in it's fully developed state of course)

JD
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Old 21st Nov 2017, 15:16
  #28 (permalink)  
 
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Fijdor:

I did a 3 year exchange with the RCAF. During that time (helicopters) they trained me to be a waterbird instructor and also gave me my mountain flying instructors badge courtesy of the Rockies. Lovely people, gorgeous country.

With reference to your Transport Canada piece:
https://en.wikipedia.org/wiki/Vortex_ring_state
In it you will see that the FAA see it the same as SWP whereas Transport Canada don't. (thank god there appears to be common sense somewhere in N America).

When it comes to VRS Fijdor - believe me you have not knowingly entered fully developed VRS, or you'd probably not be here today / bent your aircraft.

You have probably entered Incipient VRS - which is "relatively" common amongst chopper pilots who are in a slow and descending / downwind / updraft scenario. But you have trained yourself to identify the conditions - quickly. Therefore you are out of the condition before you can say Justin Trudeau!

Fully developed VRS:
VERY high RoD. (thousands of feet per minute).
cyclic / collective/yaw - erratic.
Vibration.

{Just in case you weren't aware}.
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Old 21st Nov 2017, 23:37
  #29 (permalink)  
 
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Thomas Coupling, I am glad you had a chance to fly the Canadian Rockies and liked your stay in Canada. Don't hesitate to come back and visit again.

.

JD

Here it is straight from the Transport Canada website. Copied and pasted here.

EXERCISE 26 - VORTEX RING

If the helicopter pilot chooses a flight path, airspeed and a rate of descent that coincides with the aircraft’s downwash, the helicopter could enter a condition known as the Vortex Ring state. The stall condition formed by the rate of descent flow in opposition to the induced flow, combines with the tip vortices present in all regimes of flight to produce a turbulent rotational flow on the blades and an unsteady spanwise shifting of that flow. This condition induces a very rapid rate of descent, vibrations, excessive flapping and a reduction in cyclic authority that could result in an accident. Obviously, this condition is to be avoided and the helicopter pilot should be able to recognize the incipient stage and be able to affect a safe recovery.

Your instructor will review the causes, conditions and symptoms of vortex ring. During a steep approach, at a high gross weight, high-density altitude and in a downwind or light wind condition; the helicopter may enter its own downwash and the development of vortex ring state. This situation would certainly contribute to the onset of vortex ring, but not necessarily cause it. The phenomenon is most likely to occur when all the conditions listed below are present:

in powered flight;
high rate of descent, in excess of 500 feet per minute; and
low airspeed, less than 20 MPH indicated.

Almost every transition from forward flight to a hover utilizes a powered approach, a rate of descent and a reduced airspeed. To prevent the occurrence of vortex ring, control your rate of descent less than 300 feet per minute.

Recovery Techniques. There are two methods of effective recovery from the vortex ring state. Both change the airflow conditions causing it and both involve a loss of height:

Dive out. Normally this technique will result in less altitude loss than with the autorotational recovery. The pilot should apply forward cyclic while reducing the collective; the vortices will leave the disc as the airspeed increases and the helicopter will move forward of its downwash. Normal flight may then be resumed.
Enter autorotation. By this method, the airflow through the rotor changes from the disturbed flow of the vortex ring to the upward autorotational flow. Once autorotational descent has commenced then the pilot may ease the cyclic forward to gain airspeed while power is increased and normal flight resumed.

You should note that an increase in collective alone may not result in a recovery and indeed may only serve to increase the rate of descent. This increase in blade pitch will cause the vortices to intensify in strength and will result in a more rapid descent.

There are some uninformed pilots who use “settling with power” to describe vortex ring, in fact some publications use the terms interchangeably. Confusion results when symptoms are related that do not describe true vortex ring but rather describe “settling with insufficient power”. This may occur when a pilot attempts to arrest a rapid, low power descent only to find that he has insufficient power available to bring the helicopter to either a hover or a no-hover landing without exceeding the engine limits. However, this is not a vortex ring situation.

Another situation, ‘over-pitching’ is often misinterpreted as vortex ring. This is where the pilot rapidly increases collective considerably and the engine cannot produce enough power to overcome the large, swift increase in drag on the rotor system. The result is that the rotor system quickly slows down and loses efficiency causing the helicopter instantly to sink. Again, this is not vortex ring.

The most common situations, where you would be most likely to encounter vortex ring, are usually when you misjudge the wind with a heavy load on a hot day. Downwind approaches to a confined area, or a mountain pad, are two good examples. Always control your rate of descent carefully on these occasions, and make sure an escape route is available. Your instructor will discuss the symptoms and recovery techniques more fully. Demonstration of this exercise is not generally performed, as the stresses on the airframe and rotor system are unknown.

PREVENTION IS BETTER THAN CURE!!!

Last edited by fijdor; 21st Nov 2017 at 23:56.
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Old 22nd Nov 2017, 00:12
  #30 (permalink)  
 
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Originally Posted by fijdor View Post
...I never heard anybody say anything good about it, so my question here is.

Does anybody here sees a good practical/useful side to VRS? just asking.

JD
Once while scuddrunning in an R44 I went IIMC, but eventually got clear of the clouds when I started falling after getting into VRS as well!
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Old 22nd Nov 2017, 03:12
  #31 (permalink)  
 
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Originally Posted by Thomas coupling View Post
Fijdor/Newfie:

I'm going to put your lack of knowledge about this subject down to definition misunderstanding.

And I'm not going to waste any more of my life trying to educate people who haven't thoroughly researched the subject properly.

I can't force you to DYOR.

VRS is a DEVELOPED state. It is a situation where you as the pilot become a passenger. VRS will always end in disaster if there isn't sufficient height between you and the ground. If you have sufficient height - then an attempt at recovery often leads to a successful outcome - but not always.

INCIPIENT vortex ring [IVRS] is what people like you have 'probably' been into (due to your long line work) several times. You have 'probably' noticed the symptoms of the ONSET of VRS (which is IVRS) and responded appropriately, resulting in a fairly rapid and unexciting recovery. Probably within a couple of hundred feet.

Now there are DOZENS of very well discussed conversations on PPRuNe which dive deep into this subject matter. My advice to you two is to find an hour or two and go sit in a quiet corner and research more thoroughly the subject of VRS.

If you are either american or american trained, it is also essential you learn the difference between VRS and Settling with Power (SWP), because for some obtuse and bizarre reason, even your own FAA believe the two, are one and the same

Please find time (even at your level of competency) to research the following:

VRS versus IVRS.

and

VRS versus SWP.

I continue to be amazed by how many so called professional helicopter pilots out there STILL don't understand basic aerodynamic concepts.

Frightening............................
Here in America VRS and SWP are the same thing, so there's no need to learn the difference!
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Old 22nd Nov 2017, 03:15
  #32 (permalink)  
 
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For years, i don't understand the big mistake/confusion/ of the FAA about VRS and SWP. I am a " old French school helicopter pilot" and when we are young duck, we learn the difference...Why the FAA not ?
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Old 22nd Nov 2017, 07:24
  #33 (permalink)  
 
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Please cut the FAA some slack. They are not that stupid. Actually at least to me they proved to be a quite educated, helpful and very polite bunch of people. Well nicer than some other aviation authorities I had the misfortune to deal with.

If you read the FAA Helicopter Flying Handbook in its latest version in chapter 11 page 9 you find this:

Settling With Power (Vortex Ring State)
Vortex ring state describes an aerodynamic condition in
which a helicopter may be in a vertical descent with 20
percent up to maximum power applied, and little or no climb
performance. The term “settling with power” comes from
the fact that the helicopter keeps settling even though full
engine power is applied.
The FAA sees Vortex Ring State as an aerodynamic condition and Settling with Power as the phenomenon the pilot will experience. A reasonable explanation, if you ask me. I could live with it (apparently the confusion is a result from a time the US Navy messed it up). The FAA is certainly aware of the mess about VRS and SWP in its own country and having read their stuff about it in several editions, there is a clear tendency to straighten things out. But they have to deal with a whole bunch of different types of pilots who raise their voices about everything all the time. Especially the old FI's do not read that book again they have read 30 or 40 years ago (at least nobody here did it). To keep the confusion to a minimum, the FAA has to do this slowly. One day, everybody will be on the same page.

Somebody should probably go and change the wikipedia article to be more precise.

If you want to read the whole chapter about it go HERE

PS: What many of us will not like too much is the recovery part. Read it, it might annoy you.
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Old 22nd Nov 2017, 07:53
  #34 (permalink)  
 
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fijdor, is that a lesson that is taught to students in Canada? Reading it looks like you go out and show the newbies VRS, how to get in and out, ho to recognise that you are getting in, so you can avoid, or at least know that you are getting close.

I'm sure I went through a lesson like that a couple of decades ago in a 22....
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Old 22nd Nov 2017, 08:51
  #35 (permalink)  
 
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Fijdor:
It seems TC and TC (get it: transport canada and thomas coupling) are singing from the same hymn sheet. Probably because they are not american
Are we all agreed now that you and others who say they have entered VRS several times - haven't really? It;s almost certainly IVRS.

R22butters:
C'mon now sunshine - you can do better than that, three or four hooks on your fishing line (R22, IIMC, scud running, VRS). - no subtlety at all.

Rotorbee:
For clarification - what do the FAA call the engine performance phenomena where the power available to a helicopter attempting to stop a descent is insufficient to prevent that aircraft from stopping - IE: Settling with Power?
Do they call it: Power Settling?
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Old 22nd Nov 2017, 08:58
  #36 (permalink)  

 
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I have always thought that your example is power settling.

A Canadian friend of mine explained VRS/SWP it this way (if it helps):

You could probably say that VRS is “settling with a bit of power applied” and SWP is “settling with lots of power applied.” One will happen with an empty water bucket, as you descend into the dip-site and the other will happen with a full water bucket as you prepare for a drop.

Phil
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Old 22nd Nov 2017, 10:17
  #37 (permalink)  
 
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I can't help myself - I did say I'm not wasting my life getting back into this, but it really does worry me that very experienced pilots like you Paco, still haven't gripped a fundamental phenomena like VRS or PS or SWP.

Watch and learn!

VRS is an AERODYNAMIC EVENT - it's all to do with bernoulli and air flow.
swp is an ENGINE PERFORMANCE EVENT - it's all to do with horse power and AUM.

and neither the twain shall meet (except in la la land in america ).

Please will anyone who can't or hasn't grasped this very basic phenomena (VRS/SWP) go find time to research it properly and learn to UNDERSTAND it before it bites you hard in the damn ASS FFS.
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Old 22nd Nov 2017, 10:52
  #38 (permalink)  

 
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But Bernoulli only accounts for about 2% of why anything flies....

Be that as it may, VRS only happens when power is applied, so it can't be just aerodynamic. I use the term power settling to try to avoid confusion. That way the guys over the other side of the pond can be happy as well.
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Old 22nd Nov 2017, 13:39
  #39 (permalink)  
 
Join Date: Jul 2004
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@TC: Frankly I did not have the time to read the whole latest issue of the FAA book. It's online, it's free, why don't you have a look around, too? Who knows, with time we might find something.

But there is something else you might consider. About the only organisation that really does that differentiation is TC. Until now, I have not found the term power settling or settling with power other than as synonym for VRS in any other newer official publication.
What I have found so far is that almost everybody calls it VRS(SWP) - with the brackets -, even EASA, and when pilots do have the "real" SWP it is called pilot error, plain stupid or that dreaded "sudden power loss on approach" the pilot said in the accident report.
Nick Lappos once wrote that this effect was also called HTG (Hit The Ground).

From the dumb fat and happy pilot's perspective the two terms are not that far apart. From SWP/PW you can get into VRS, circumstances permitting. To solve the problem, the pilot must do the same thing - speed up, flee, get out of there, try again. Having said that, Vuichard disciples would be in for a surprise, if it was SWP and not VRS.

I personally think we should consider the following. Get rid of one of the terms, preferably SWP and never to bring it up again in any pilot handbook or publication.
It would probably save a lot of bytes in the long run. On the other hand, that would deprive us from a very funny discussion theme.
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Old 22nd Nov 2017, 14:24
  #40 (permalink)  
 
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1/You make a vertical approach but you are :
heavy
down wind
low speed , nearly zero..
High rate of descent...
You are in good conditions to going to VRS...but not sure at 100% Sometimes nothing happens...

2/From the edge of the Grand canyon, you go in hovering just at the power limit nearly 95 %... you translates slowly to te grand Canyon....When you arrive above the Grand Canyon, you lose the IGE and you falling down : That is Settling with power and sure at 100% it's happens all the time..

The really one difference is , you need much more power in OGE than IGE....no matter with thewind, yourspeed or your rate of descent asYour are hovering..but VRS is aerodynamic and SWP is justa power matter.. and exactly 7%...No more, no less
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