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Old 12th Sep 2017, 20:03   #261 (permalink)
 
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Minor rant and then I will grab my hat and coat and head for the door.
"Settling with Power" and "Vortex Ring State" are two totaly separate events.
Both can require a change of underwear if not dealt with but I am so tired of folks lumping them into the same bag of bad things you can experience.
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Old 12th Sep 2017, 20:06   #262 (permalink)
 
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View My Video
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Old 12th Sep 2017, 20:23   #263 (permalink)
 
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Quote:
Originally Posted by Hughes500 View Post
Flimsey

I assume the altimeter is on QNH in which case your instructor is not a wise man demonstrating VRS with less than 1500 ft underneath him.
In fact presumably not in VRS but IVRS
Hello Hughes. It's over a year ago, when I was probably at about 120hrs TT, so the whole thing was quite daunting to be honest.

Screenshot would suggest QNH on steam gauge and QFE on PFD. As to competence of the instructor, I'm led to believe he's got a pretty solid reputation here and in the States, but maybe that's the RHC viewpoint and not that of the wider industry.

If you're able to view the video I posted, you'll see the VT nips the 2200fpm rate of descent in the bud almost immediately.

I'm obviously a simpleton, but do you suggest that this is not developed VRS, even at that rate of descent and what seemed like serious vibration and instability?

I'm not being facetious, just trying to draw my own conclusions presented with a differing set of 'facts' to deal with.

EDIT - I guess whether 2200fpm qualifies as IVRS or VRS or FDVRS, it's still a bad do if it happens at 100ft...

Last edited by FlimsyFan; 12th Sep 2017 at 20:41. Reason: Addition
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Old 12th Sep 2017, 22:05   #264 (permalink)
 
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Quote:
Originally Posted by n5296s View Post
Seems to me that whenever you're HOGE you're spring-loaded for IVRS.
That's among the most scary parts I've learned from PPRuNe. There was that guy doing geometer-work where he had to hover HOGE so that some vertical [email protected] pointer would be hitting the helo's belly inside a 10" x 10" sensor section, hence effectifely staying pinned at some 1000 ft AGL, ROD being 0. He claimed that during this prolonged HOGE he would get inevitably and demonstrably into IVRS.
That somehow doesn't add up to them vids showing the live powerline cleaning stunts which presumable never have such VRS issues, but one truly gets the impression that HOGE has one "springloaded" for VRS.
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Old 12th Sep 2017, 22:19   #265 (permalink)
 
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Flimsyfan - thanks for the video - what it does show clearly is that while he is talking about high RoD, he has over 10 degrees nose down.

Now that to me looks like a fudge - 10 degrees nose down will give you a high RoD in any helicopter and it would also mean that by the time you pulled power to try and recover, you already have enough forward speed not to be in VRS anyway.

He then pulls the nose up and, strangely enough, the RoD reduces rapidly with aft cyclic and power applied.

Definitely not convinced by that demo.
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Old 12th Sep 2017, 22:31   #266 (permalink)
 
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As I say, it's quite a while back, but my recollection is that the nose drop was a function of the VRS rather than a deliberate input.

If the nose down was what instigated the ROD, would the airspeed not increase as a consequence? Would 10 degrees really equate to 2200fpm in a matter of seconds with 40% torque?

It seemed to me at the time that the acceleration in rate of descent was quite breathtaking - more so than an aggressive entry into autorotation.

The good thing to come out of all this for me is to keep the main contributing factors to VRS firmly in mind and avoid any iteration of VRS in the first place.

I promise, I am trying to understand...
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Old 13th Sep 2017, 09:27   #267 (permalink)
 
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Flimsy - at all seems to be over far too quickly for a proper entry into an aggravated full VRS - initially he pulls the nose up to wash off the speed with, from what I can see, 40% Tq applied.

Then he falls behind ETL and describes the 'drop' and an almost instant 2000'/min RoD and by then the nose is 10+ degrees down - then he pulls in power.

So what he has done is enter a slow speed, almost autorotative descent - I expect the Min Pitch on Ground Tq is between 15 and 20% - at least with a very low power.

We can't see from the video what happens to the IAS at this point but with that nose down it will be increasing to take you out of VRS conditions so applying full power will inevitably recover the situation.

To be convincing, he needs to get the descent going, maintain the low IAS and then pull pitch in that configuration - that would induce full VRS.

I don't think he would fly out of that in a few seconds.

As I said earlier, VRS accidents/incidents usually occur with an already high pitch/Tq setting - often in trying to come to an OGE hover or controlling a steep/downwind approach.

The use of roll rather than pitch would be better in the event of a downwind approach since it is a quicker route to clean air but that's the only place I can see it being of value (unless there is a mountain in the way).

If anyone has more convincing video footage of this 'technique' then it would be good to see it.
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Old 13th Sep 2017, 10:14   #268 (permalink)
 
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You are slowly coming around to it Crab .....even just a little bit !! So you say that in a downwind approach a roll may be quicker ( which makes sense as pitch forward is going with the air ) . On the basis that full VRS is unlikely ...or MORE likely to happen in a downwind approach then this technique could by definition quite regularly be the best action ??!!
So not withstanding that we all agree the old method works ......maybe this technique should be taught as another tool in the tool box that all pilots need for a long life ! That is a massive change in the old guards stance i would say ....is TC in with you or are you going it alone ??
Lets not lose sight that we are all , joking aside, interested in making our profession or hobby safer . However i believe like many others that for 90% of pilots there should be no reason to ever get near full VRS even if you are stupid !
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Old 13th Sep 2017, 11:01   #269 (permalink)
 
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Not quite Nige - although there may be merit in roll rather than pitch in limited circumstances the 'technique' hasn't been demonstrated in full VRS which is the condition it has been touted to be so special and new in.

Neither the Vuichard video nor the one from the Robinson course come close to being convincing.

So, no change from me really
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Old 13th Sep 2017, 11:07   #270 (permalink)
 
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Quote:
Originally Posted by Hughes500 View Post
Flimsey

I assume the altimeter is on QNH in which case your instructor is not a wise man demonstrating VRS with less than 1500 ft underneath him.
In fact presumably not in VRS but IVRS
When Tim Tucker demonstrated this technique to me as part of a Robinson course, we only had a 1000'-1100' cloud base. He was happy putting the machine in an 800FPM descent VRS before using the Vuichard technique to pop out at around 600'. I managed to slot it into more like 1000 FPM accidentally when it was my turn, pulling about 23" MAP. Popped out as per the Vuichard video in around 100' once the recovery was initiated. I was impressed.

Whether or not I could pull it out of the bag at the gravy stroke is another thing altogether...
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Old 13th Sep 2017, 12:01   #271 (permalink)
 
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...and I thought the Vuichard technique was designing nice web sites.

Vuichard Recovery Aviation Safety Foundation

Quote:
Popped out as per the Vuichard video in around 100' once the recovery was initiated.
Bzzzzzz: Incorrect. The web site says 20-50 ft.

Ya'now, VRS is next to impossible on a windy gusty day. Therein lies the answer.
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Old 13th Sep 2017, 12:23   #272 (permalink)
 
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Having read and re-read the link you sent about Vuichard's web page, and having looked at the testimonies regarding departure from the VRS, I am genuinely beginning to wonder if there is a difference in translation here between european definitions and ours.
For the same reasons many of us get confused/mixed up over:
SWP and PS,
and
LTE and LTA

I think Vuichard et al is using VRS to cover IVRS.

Just think about it. He harps on about side slipping out of the tunnel of vortices below the tip path plane and making a miraculous recovery between: "20 - 50 feet".
Let's analyse this shall we - IF Vuichard insists he is talking about FULLY DEVELOPED VRS, we would have an aircraft descending at around 3,4,5000 feet per minute, oscillating around pitch, roll and yaw and he then swiftly drags the cab sideways out of the disc effect and arrests this descent and wayward aircraft movement within 20 to 50 feet. That would suggest a massive stop effectively, of the entire descending helicopter which in reality would break something, I would suggest!
This leads me to suspect that all along, Mr Vuichard is really discussing IVRS where (even in asociated videos) he rarely descends greater than 1 or 2000fpm. His beautiful web based video looks like a descent of hundreds of feet - maximum and a relatively stable helicopter platform.

So, in summary: If Mr V really means IVRS, yes, his technique would work (although even then, 20-50 feet halt distance is still unlikely).

But if he insists he is demonstrating FDVRS, he is either:
A liar.
Stupid.
Incompetent.
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Old 13th Sep 2017, 12:40   #273 (permalink)
 
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Quote:
But if he insists he is demonstrating FDVRS, he is either:
A liar.
Stupid.
Incompetent.
It smells of salesmanship to me by creating a little contentious controversy to what is considered common lore which brings attention to his other activities. Yes, he must be discussing IVRS in which case being a little less smooth on the controls would often keep you out of the poo. I've heard the Aaaaa-Chooo recovery technique works just as well for IVRS.

Nice web site but.
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Old 13th Sep 2017, 16:06   #274 (permalink)
 
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And we go in circles ... again. No reason to spare you my five cents.
A few things you might consider.

We have to parties here, one party consisting of mostly very or less experienced Robinson pilots who claim the darn thing works. And I think we can trust Paul Cantrells judgement when he says he thinks it works quite well.

In the other corner some very known figures in our business with a lot of experience and knowledge. Many of those would not touch a Robby with a pole.
I also think we can trust Vertical Freedom that he also knows what he is saying, and crab, and TC and so on.

Might it be possible, that the Vuichard Technique is more effective in a Robinson? Or in two bladed rotor systems?

Next question. What the h*** is the point?
I personally find it rather appalling that Vuichard is calling it his technique, when we know he was not the first. Apart from that fact, it is just very, very bad style (let's just say not everybody in Switzerland sees the greates helicopter pilot of all times in him). But aerodynamically why not let the thing work in certain circumstances? Who cares? It is not going to help a lot of people because it solves a problem that isn't really there. Only Vuichard claims hundreds of accidents happen because of VRS. Nobody else. Probably he almost died once a week because he did not realise what was going on when the controls get sluggish and the ride more uncomfortable. He probably always thought what a hero he is making through these terrible turbulences when in reality he did not recognise VRS ... again. Until the day he pushed the pedal and voilà, he was saved from the daily terror.
And with all those videos that are a lot of show and few substance, he just makes an a** of himself.

I find it rather strange when the chief instructor of Robinson demonstrates IVRS happily from 1'000 ft. But thinking about it, he lost 400 ft. Well, nice demo, but what students should learn is to loose no feet whatsoever. It would be a rare event if you have 400 feet below you while hovering and descending. That is not a place we like to be, and if we have to, we try to do that very gently. It just isn't something that is common place (You may demo VRS till the cows come home, but that isn't the point when learning about how to avoid it).
Therefore who cares what technique you are using to get out of it, when the height lost to get into it is far more important. Because it takes quite a while to get even a Robinson to shake like a bull in a rodeo.
What a student must learn is to recognise the danger early and then just a gentle forward pressure on the stick will already have saved the day. There is not point of neither dropping the collective to the floor and shoving the stick to the forward stop nor pushing the pedal one direction (powerpedal apparently) and the stick in the other - something that does not come naturally to us rotorheads and even Robinson does not like you to do it in a mariner with the floats on, because the thing can flip, given enough sideward speed.
Therefore guys, let it rest. Vuichard and his disciples will not stop. As he said, he is pursuing a place in the Smithsonian alongside Lindberg. People like that are hard to argue with.

Last edited by Rotorbee; 14th Sep 2017 at 07:18. Reason: Said that allready ...
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Old 13th Sep 2017, 16:29   #275 (permalink)
 
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The website press-release has a hint of the paranoid 'The system knows this is the answer but they're keeping it quiet' conspiracy theory.

Fist it references the Sumburgh accident which was caused by mismanagement of the AP and poor CRM, the fact that they eventually entered VRS was just seconds before impact.

I would love to see him use his famous recovery technique in a situation like that.

His only other example of the
Quote:
Every year, numerous helicopter accidents happen due to the vortex ring state.
which is the opening gambit is an instance when he frightened himself in the mountains on long-line work.

They talk a lot about the 'suction' from underneath the rotor and how you need to get away from it - are they really the words of an aviation professional?

So the only other person to 'validate' this technique is Tim Tucker who may or may not have a vested interest in adding something that looks like good value to the Robinson Safety Course other than 'don't chop the tail off'.

It would be interesting to know how many other manufacturers have been offered/shown this technique since no-one else seems to be interested in it.

Perhaps the secret lies in the words of the website
Quote:
However, the
certification specifications CS27 and CS29, analogical to the FAR27/29 in the United States, do not require a defined maneuver in order to escape the
“vortex ring state”.
since the FAA helicopter flying handbook defines
VRS as
Quote:
A transient condition of downward flight (descending through air after just previously being accelerated downward by the rotor) during which an appreciable portion of the main rotor system is being forced to operate at angles of attack above maximum. Blade stall starts near the hub and progresses outward as the rate of descent increases.
it would be quite difficult to specify such a manoeuvre.

Therefore you can call any low speed descent VRS and claim a recovery technique for it.
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Old 13th Sep 2017, 20:34   #276 (permalink)
 
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http://sendvid.com/wemap6we

A further video from last year's training. In spite of all the arguing, I've actually found this thread quite informative.

Last edited by FlimsyFan; 13th Sep 2017 at 22:12.
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Old 13th Sep 2017, 21:08   #277 (permalink)
 
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Quote:
Originally Posted by FlimsyFan View Post
...In spite of all the arguing, I've actually found this thread quite informative.
2nd that..

I find arguing is good, makes yer think about it in a more in depth way.





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Old 14th Sep 2017, 09:48   #278 (permalink)
 
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PPrune - the virtual crewroom
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Old 14th Sep 2017, 11:01   #279 (permalink)
 
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...so, where is the Uckers board then?
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Old 14th Sep 2017, 11:47   #280 (permalink)
 
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Once aaaat!
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