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Condition for Vortex Ring

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Condition for Vortex Ring

Old 22nd Nov 2017, 14:53
  #41 (permalink)  
 
Join Date: Aug 2000
Location: UK
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Breath deeply and count..............................

OK..........mindfullness over.

Rotorbee - you disappoint me.

Bobakat:

When an a/c develops VRS or IVRS, 'stuff' happens inside the lift drag curve where big green arrows and vectors and angles of attack all start moaning and complaining they aren't happy and as a result of this quiet revolution going on around your rotor disc, the aircraft says F-u-*-k it, I'm outta here and goes into freefall.
No one else has come along and spoilt the party - it's all down to that nasty neighbourhood and bunch of trouble makers the "aerodynamic gang".

When an a/c develops SWP, you're in a different neighbourhood. You're in the engine neighbourhood - the hot gas clan - those nasty individuals who spend all day hitting that huge compressor at the back of the class.
The a/c needs to stop as it ends its decent to land or is approaching an obstacle and the hot gas clan come out in force until all of them that are available are hitting the compressor kid as hard as possible, to the extent where the engine says to hell with this excessive violence in my classroom, enough is enough, we cannot continue to produce the output you require from this compressor to bring the MASS of this a/c to a stop (before it hits the ground/obstacle).

Look at it another simplistic way:

You are landing your jumbo jet at Heathrow and for that given AUM you decide to apply maximum reverse thrust to prevent yourself running off the runway. But all the reverse thrust available is not sufficent to arrest the AUM in time to keep it on the runway. Your engines aren't powerful enough (IN THE REMAINING DISTANCE OFFERED) to arrest your particulr AUM.

It is an engine thang! Nothing to do with little green arrows/updraft/alpha.

Learn the difference guys and don't show your ignorance in basic helicopter theory FFS.

Calm..............close my eyes.....relax........
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Old 22nd Nov 2017, 17:32
  #42 (permalink)  
 
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TC, you break my heart. Nothing could be more hurtful than your accusation that I disappoint you ...Er, why exactly?

PS: BOBAKAT and TC - don't you two mean the same thing but keep misunderstanding each other? VRS - aerodynamics, SWP - Pooooowwwweeeer
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Old 22nd Nov 2017, 17:36
  #43 (permalink)  
 
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Originally Posted by Thomas coupling View Post

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?
He wanted to know if anyone had anything positive to say about VRS? Well I do,...it saved my life once!,...and it was in a 44!

I don't know what the FAA calls it when you have insufficient power to stop your decent, but I call it FTS.
FULL THROTTLE STUPID!

"Sunshine"? HA! No one who's ever met me would ever call me that! It was a good laugh though!
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Old 22nd Nov 2017, 19:38
  #44 (permalink)  
 
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Originally Posted by Thomas coupling View Post
Breath deeply and count..............................

OK..........mindfullness over.

Rotorbee - you disappoint me.

Bobakat:

When an a/c develops VRS or IVRS, 'stuff' happens inside the lift drag curve where big green arrows and vectors and angles of attack all start moaning and complaining they aren't happy and as a result of this quiet revolution going on around your rotor disc, the aircraft says F-u-*-k it, I'm outta here and goes into freefall.
No one else has come along and spoilt the party - it's all down to that nasty neighbourhood and bunch of trouble makers the "aerodynamic gang".

When an a/c develops SWP, you're in a different neighbourhood. You're in the engine neighbourhood - the hot gas clan - those nasty individuals who spend all day hitting that huge compressor at the back of the class.
The a/c needs to stop as it ends its decent to land or is approaching an obstacle and the hot gas clan come out in force until all of them that are available are hitting the compressor kid as hard as possible, to the extent where the engine says to hell with this excessive violence in my classroom, enough is enough, we cannot continue to produce the output you require from this compressor to bring the MASS of this a/c to a stop (before it hits the ground/obstacle).

Look at it another simplistic way:

You are landing your jumbo jet at Heathrow and for that given AUM you decide to apply maximum reverse thrust to prevent yourself running off the runway. But all the reverse thrust available is not sufficent to arrest the AUM in time to keep it on the runway. Your engines aren't powerful enough (IN THE REMAINING DISTANCE OFFERED) to arrest your particulr AUM.

It is an engine thang! Nothing to do with little green arrows/updraft/alpha.

Learn the difference guys and don't show your ignorance in basic helicopter theory FFS.

Calm..............close my eyes.....relax........
Hmm, the way you are describing it here makes it sound more like a distance thang to me! Its not settling with power, its just not paying attention!

Its like driving in the rain or ice, if you want to stop in time, you need to start slowing down sooner!
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Old 22nd Nov 2017, 20:19
  #45 (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.
TCoupling bare with me as you have probably noticed the English language is my second language, I am French Canadian.

No worries I see your point. Also I realized last night that there are no confusion in what VRS actually is or what it can do to you or how to recognize the first signs of it or confusion on how get out of it. The confusion/misunderstanding here is in the word itself.
Now let see if you will see my point. The text from TC pasted earlier says "incipient" you are right, but nowhere in any books or anywhere else during your initial training or annual training do they use IVRS. For us here in Canada the term incipient means you are at the beginning , first stage, the start of VRS. We have no separate or different terms to describe the different stages or the evolution of the condition from its beginning/early stage to its fully developed condition.
That you are in it at the beginning or at the end coming down 25,000ft a second it is still only called VRS. First time I heard of IVRS is here on this forum. (earlier tread)
This winter when I start giving training and if I start using the term IVRS they will all look at me and say something like, Are you sure you want to wait another 2 years before retirement. lol Now if you say that before we can call it VRS, it has to be in its full development or solidly on its way there then that might take while to get implemented in this industry.
But again I see your point.

For SuperF, yes it is a lesson or exercise 26 and part of what a student pilot should learn to get his license. But I am not not an instructor and I am not up to speed with how they teach it. I am a training pilot and give annual company training to professional pilots on Mediums (205 nowadays) and also longLine training where VRS SWP are an important part of it. 205 are notorious to get into SWP on a hot and humide day when loaded. Most of the pilots here have a good understanding on the differences of the two conditions. I do have a way of explaining both conditions if needed.

JD
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Old 23rd Nov 2017, 00:50
  #46 (permalink)  
 
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fijdor,

my memory must be still working alright. it was in a 22 a long time ago, and I'm now far more comfortable in a 204 myself. totally agree that you can get all sorts of "fun" in a Bell medium if hot, high, heavy or a combination, especially sitting on top of a longline as you try to sink 200" into the "hole" in the trees!
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Old 23rd Nov 2017, 01:52
  #47 (permalink)  
 
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Tabernac!

Careful boys - this is what fijdor looks like after he gets frustrated!



Ça va, JD?
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Old 23rd Nov 2017, 06:03
  #48 (permalink)  
 
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The other way of considering the difference between VRS and SWP is to look at Nr.

In SWP, you have run out of power - but keep pulling anyway - the Nr will decay and you will descend - often to ground impact.

In VRS, you have run out of lift - because of the stalled roots and the vortex-ingesting tips - you can get to this stage without running out of power.

The 'lesson' given to students about VRS often involves flying downwind at 1500' or so, reducing speed below 30 kts and then allowing a slight RoD to develop - at this point the lever is raised and the ensuing vibration is described as VRS (it isn't VRS) and immediate recovery is made by increasing speed and flying out.

The student is scared by the vibration and the instructor has shown the conditions for entry - everyone goes away happy but there has been no VRS demonstrated or recovered from - only what we are now calling IVRS.

It's a bit like the difference between FW spin recovery (from a fully developed spin) and incipient spin recovery - one involves a specific series of actions to recover from the high RoD into controlled flight and the other usually just requires centralisation of the controls.

The difference between incipient spin and fully developed spin is large - in exactly the same way that the difference between IVRS and VRS is large.
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Old 23rd Nov 2017, 06:21
  #49 (permalink)  
 
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Hi Crab,
Some of us got the other lesson. Climb out to about 8,000’ in a 22. Yes it took a while from memory... same start of lesson, turn down wind, pull airspeed back to zero, start a descent, shaking scary stuff, pull power, going down faster, I remember the VSI being pegged as low as it would go. After what seemed like an hour, and loosing a few thousand feet, we started a recovery and came out about 1000”.

Scared the crap out of me, but I made sure everything was done into wind after that!
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Old 23rd Nov 2017, 16:12
  #50 (permalink)  
 
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Hi Super F - yes that sounds like the real deal alright - I hope everyone reads your post and realises the difference between what you experienced and what so many others get.

I wonder how confident Mr Vuichard would have been in his 'technique'...........
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Old 23rd Nov 2017, 17:35
  #51 (permalink)  
 
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Originally Posted by SuperF View Post
Hi Crab,
Some of us got the other lesson. Climb out to about 8,000’ in a 22. Yes it took a while from memory... same start of lesson, turn down wind, pull airspeed back to zero, start a descent, shaking scary stuff, pull power, going down faster, I remember the VSI being pegged as low as it would go. After what seemed like an hour, and loosing a few thousand feet, we started a recovery and came out about 1000”.

Scared the crap out of me, but I made sure everything was done into wind after that!
Last time I did SWP downwind like that I got an immediate, surprise 90° yaw,...startled the shit out of me! He had me do that new sideways recovery technique,...its pretty cool!
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Old 23rd Nov 2017, 18:25
  #52 (permalink)  
 
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No butters, your trolling still doesn't have any subtlety....................
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Old 23rd Nov 2017, 18:54
  #53 (permalink)  
 
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Originally Posted by [email protected] View Post
No butters, your trolling still doesn't have any subtlety....................
Nope, that actully did happen!
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Old 23rd Nov 2017, 19:20
  #54 (permalink)  
 
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I don't know where some of you guys are coming from. The U.S. FAA teaches now...has always taught...that "Settling With Power" is recirculation of the vortices produced by the main rotor. I won't reprint or repost the applicable section of the FAA's Helicopter Flying Handbook - you can read it yourself. But it's what I was taught when I was learning to fly in the 1970's. To recap: The FAA says that SWP *is* VRS.

But because the current generation of Robbie Rangers have to over-complicate and try to quantify EVERYTHING, some of you have invented your own definition and explanation of SWP - that of a botched approach (vertical or otherwise) in which the engine does not have enough power to stop the descent. Fine. Sounds like pilot screwupery to me. And strangely, the FAA does not address this "phenomenon" or aerodynamic condition directly. I guess they leave it up to the pilot to know the performance characteristics of his or her particular helicopter and abide by them and not land on a runway so short that full reverse won't stop you. You know, that's not the plane's fault.

In reality...in the real world of helicopter flying, it *almost* doesn't matter what you call it, or whether it's "settling without enough power to stop" or true vortex recirculation. You're probably going to crash. Yeah, yeah, if you recognize it early you might be able to employ Sr. Vuichard's technique (good luck!)...*or*...you might be able to fly out of it forward. But you usually get into it until the very bottom of a poorly-executed approach...you know, where it usually happens to those of us who don't have things dangling under our helicopters on longlines. And if it does happen at the bottom of such a messed-up approach, and you're a little slow to recognize what's happening (welcome to the club!), then you'll probably end up with smiling skids and your peers will be calling you by the nickname Bing Dang Ow from now on. (Ohhhh, just remembering that bimbo newscaster blithely reading the fake names of those Asiana Airline pilots makes me chuckle.)

I often tell the story (faithful readers of my crap have all heard it by now) of sitting in the Vibro-Massage chair attached to the Bo-105 I was flying in the Gulf of Mexico. I'd be on approach to some drilling rig which was situated in a way that the heliport was on the exact WRONG side of the rig for the winds that day. And I'd sit there, pretty much at full power as the 105 did it's notorious shake, rattle and roll coming back through ETL...I'd sit there wondering, "Is this just the 'normal' Bo-105 vibrations, or are we on the edge of SWP?" I'd be super-attentive to the collective, waiting for it to become "unhooked" from the RoD. Because you never know, right? No, you never do.

People ramble on and on about the "differences" between SWP and VRS. They say that during SWP, because you're pulling more than the engine can supply then the RPM will droop. Well...you know...aaaahhhh...most of real helicopter pilotos fly real helicopters powered by this new invention called the turbine engine. We don't pay much attention to the trials and tribulations of the unwashed, bearded riff-raff in the R-44's. I mean, really. And these modern turbines don't droop.. (At least not anymore! Anybody remember the Allison C-18 days? I do. And not fondly.)

So prattle on, boys...drone on and on about how there's such a BIG difference between SWP and VRS. The more experienced pilots among us will just chuckle and shake our heads and fly 'em the way we know how.
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Old 23rd Nov 2017, 19:22
  #55 (permalink)  
 
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What difference does it make going down wind at several thousand feet? Might as well practice your VRS entry in any direction?
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Old 23rd Nov 2017, 20:05
  #56 (permalink)  
 
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Originally Posted by FH1100 Pilot View Post
I don't know where some of you guys are coming from. The U.S. FAA teaches now...has always taught...that "Settling With Power" is recirculation of the vortices produced by the main rotor. I won't reprint or repost the applicable section of the FAA's Helicopter Flying Handbook - you can read it yourself. But it's what I was taught when I was learning to fly in the 1970's. To recap: The FAA says that SWP *is* VRS.

But because the current generation of Robbie Rangers have to over-complicate and try to quantify EVERYTHING, some of you have invented your own definition and explanation of SWP - that of a botched approach (vertical or otherwise) in which the engine does not have enough power to stop the descent. Fine. Sounds like pilot screwupery to me. And strangely, the FAA does not address this "phenomenon" or aerodynamic condition directly. I guess they leave it up to the pilot to know the performance characteristics of his or her particular helicopter and abide by them and not land on a runway so short that full reverse won't stop you. You know, that's not the plane's fault.

In reality...in the real world of helicopter flying, it *almost* doesn't matter what you call it, or whether it's "settling without enough power to stop" or true vortex recirculation. You're probably going to crash. Yeah, yeah, if you recognize it early you might be able to employ Sr. Vuichard's technique (good luck!)...*or*...you might be able to fly out of it forward. But you usually get into it until the very bottom of a poorly-executed approach...you know, where it usually happens to those of us who don't have things dangling under our helicopters on longlines. And if it does happen at the bottom of such a messed-up approach, and you're a little slow to recognize what's happening (welcome to the club!), then you'll probably end up with smiling skids and your peers will be calling you by the nickname Bing Dang Ow from now on. (Ohhhh, just remembering that bimbo newscaster blithely reading the fake names of those Asiana Airline pilots makes me chuckle.)

I often tell the story (faithful readers of my crap have all heard it by now) of sitting in the Vibro-Massage chair attached to the Bo-105 I was flying in the Gulf of Mexico. I'd be on approach to some drilling rig which was situated in a way that the heliport was on the exact WRONG side of the rig for the winds that day. And I'd sit there, pretty much at full power as the 105 did it's notorious shake, rattle and roll coming back through ETL...I'd sit there wondering, "Is this just the 'normal' Bo-105 vibrations, or are we on the edge of SWP?" I'd be super-attentive to the collective, waiting for it to become "unhooked" from the RoD. Because you never know, right? No, you never do.

People ramble on and on about the "differences" between SWP and VRS. They say that during SWP, because you're pulling more than the engine can supply then the RPM will droop. Well...you know...aaaahhhh...most of real helicopter pilotos fly real helicopters powered by this new invention called the turbine engine. We don't pay much attention to the trials and tribulations of the unwashed, bearded riff-raff in the R-44's. I mean, really. And these modern turbines don't droop.. (At least not anymore! Anybody remember the Allison C-18 days? I do. And not fondly.)

So prattle on, boys...drone on and on about how there's such a BIG difference between SWP and VRS. The more experienced pilots among us will just chuckle and shake our heads and fly 'em the way we know how.
Easy there turbine boy! Don't blame this crackpot "SWP isn't VRS" crap on Robbie Rangers! We're the ones who still believe the textbook!
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Old 23rd Nov 2017, 20:43
  #57 (permalink)  
 
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Originally Posted by RVDT View Post
Tabernac!

Careful boys - this is what fijdor looks like after he gets frustrated!



Ça va, JD?
RVDT, you funny guy you. lol Oui ca va. Looks like they took THAT picture out of the message.

JD
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Old 23rd Nov 2017, 20:47
  #58 (permalink)  
 
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FAA's Helicopter Flying Handbook - you can read it yourself. But it's what I was taught when I was learning to fly in the 1970's. To recap: The FAA says that SWP *is* VRS.
Your FAA "Bible" has a lot of Fake News in it, being designed to teach the lowest common denominator, so it glosses over things and simplifies them to the point of error.

For example, it states as a fact that the air pressure increases under a rotor disk in IGE, causing less induced flow. Wrong.

On page 2.19 it shows a diagram from above with coloured part on the right saying that with forward motion, the advancing side gets more lift, and the retreating side gets less lift (IF NOTHING IS DONE ABOUT IT) and this will cause the aircraft to roll left. Garbage.

It preaches gyroscopic precession, which should only be used as a guide to understanding the delays in blade movement and the advance angles built into the swash plate to make up for them, not as the reason the disk behaves like it does.

So don't quote the FAA book as being absolute truth, it is merely a teaching aid, and not a particularly good one at that.
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Old 23rd Nov 2017, 22:53
  #59 (permalink)  
 
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TC,
We hear where you coming from Mate. Your experience seems to be Mil/Police/Medevac etc. We get that.
One simple question how much time you got in the mountains, and I don't mean the Beacons, at altitude, heavy all day, single pilot doing the longline stuff we do in Canada?
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Old 24th Nov 2017, 01:03
  #60 (permalink)  
 
Join Date: May 2010
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Originally Posted by chopjock View Post
What difference does it make going down wind at several thousand feet? Might as well practice your VRS entry in any direction?
I guess that was asked to me? I've got no idea, except maybe if you are doing it into wind, that when you get into the falling out of the sky part, that you are actually travelling backwards relative to the ground. I doubt if that makes any difference to the actual experience, but "maybe" it was proving the point that its best to make an approach into wind when you can.

Having never done any instructing, i would only be guessing.
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