Vuichard technique for settling with power?

[n5296s]

Anyone have anything to say about the Vuichard technique? According to Wikipedia:

Another recovery technique is called the Vuichard Recovery Technique: initiate the recovery by increasing the collective to takeoff power, then simultaneously applying power pedal to maintain heading and opposite cyclic (15-20 degree bank) cross controls to get lateral movement. As soon as the rotor disc reaches the upwind part of the vortex the recovery is completed. Average loss of altitude during the recovery is 20-50 ft depending on the duration of the recovery procedure.

I was flying with an instructor and a friend at the weekend and we had a for-real SWP, trying to hover OGE close to gross in an R44. (We were at or very close to redline, though my experience in other R44s is that HOGE at 1000 feet at gross is no problem, no idea why this one is different).

The recovery was simple and quick, but my friend got interested and asked me what I thought of the Vuichard technique. Since I'd never heard of it, I thought I'd ask here.

[alouette]

It actually works on any helicopter. Left pedal and right cyclic to pull out or vice versa. It helps. :ok:

[[email protected]]

Probably worth clarifying whether you are talking about recovery from VRS or SWP since they are not the same.

I'm sure that technique would work for VRS but not convinced for SWP (where you haven't got enough power to hover and begin to overpitch).

[Helilog56]

Didn't know it had a name....I was taught that technique back in the 70's by my flight instructor.

[Hawkeye0001]

Just did it in direct comparison to "normal" recovery technique during a base check with someone the other day. It is really astonishing just how much quicker the recovery is and would recommend anyone to give it a try. In a side by side comparison both of us on board managed recovery from fully developed VRS within 50 feet consistently while the normal technique always required at least 100 to 150 feet. However it does feel a lot more violent going through the Vortices.
When it comes to SWP I don't think I'd use that technique though: pushing full left pedal, entering a 10-20° bank, exposing the whole fuselage to more drag by going sideways and the need to bring in collective would certainly aggravate any settling with power situation.

[the coyote]

I am not questioning that the technique might or might not work.

recovery from fully developed VRS within 50 feet

I find that impossible to believe. Hawkeye0001, how long were you established in VRS for, and what was your ROD when you initiated the recovery action using this technique?

If your ROD lets say was only a mere 2000fpm in VRS, then a 50 ft recovery would take only 1.5sec, a huge deceleration.

Perhaps your definition of "fully developed VRS" may not be correct? I don't want anyone thinking they can recover from this condition in 50 ft, because in my humble opinion, that isn't possible.

[oleary]

For both VRS and SWP?

[Hawkeye0001]

I find that impossible to believe. Hawkeye0001, how long were you established in VRS for, and what was your ROD when you initiated the recovery action using this technique?Starting into VRS at 1,500' AGL we let it develop until we hit a descent rate between 800 and 1,100ft / min, started recovery at approx. 1,200' AGL and were able to arrest the descent by about 1,150' AGL give or take some 20ft.

Perhaps your definition of "fully developed VRS" may not be correct? I don't want anyone thinking they can recover from this condition in 50 ft, because in my humble opinion, that isn't possible.Perhaps my definition is not correct, I'm sure that with a 2,000ft/min descent rate (if that is the definition of "fully developed" we go by) you are right in that the 50' quoted are definitely not manageable. But 1,100ft/min is bad enough in my book that you should have begun your recovery a long time before you even got to that point.
And the point is that in direct comparison to the method of lowering collective, accelerating forward, hit ETL, and then raising collective to climb out the Vuichard technique consistently saved us approximately 1/2 to 2/3 of the way on side-by-side comparision throughout 6 attempts of using each method.

[ShyTorque]

The type I fly isn't even likely to get into VRS until it reaches a ROD of 900ft/min. At least, not according to the RFM, which advises pilots to avoid RODs of greater than 900ft/min at low airspeeds.

The one time I saw "proper" VRS on the Puma HC1 the VSI needle was pegged at the bottom, 2,500 ft/min or more.

[Torquetalk]

Echo that. Bigger (higher mass) helicopters get into VRS at a higher rates of decent, and correspondingly require more height to recover. Simulating incipient VRS and recovery at trainer helicopter heights is only for the soon to be dead or unemployed. Ditto zero speed autos.

[chopjock]

the coyote
Perhaps your definition of "fully developed VRS" may not be correct? I don't want anyone thinking they can recover from this condition in 50 ft, because in my humble opinion, that isn't possible.

Perhaps that depends on your definition of "recover"

[Democritus]

Almost 50 years ago I flew with an ETPS graduate in a RN Wasp. He demonstrated fully developed VRS - and I do mean it was really fully developed - we started at 9000ft, commenced the recovery at about 8000ft and recovered at just above 4000ft with the ROD having been pegged to the bottom of the dial. No way can you recover from fully developed VRS within 50 ft!!!!

I do appreciate that a Wasp in auto is like a brick built outhouse anyway but it was a very sobering demonstration of how much height it took to get out of VRS. I shall remind him of that trip when we meet for lunch next month.

[n5296s]

Thanks for the replies everyone. Very interesting. I'll ask the instructors where I fly if they know about it.

Not sure I follow the distinction between VRS and SWP. Looks as though the idea is that one is what happens in (e.g.) a steep approach, where you're descending at reduced power, while the other is what happens when you try to hover OGE and don't have enough oomph to make it work (as happened to me). But it also looks as though Crab and Hawkeye are using them opposite ways round.

Aerodynamically, aren't they the same thing? The FAA Rotorcraft Flying Handbook has a section called "Vortex Ring State (Settling With Power)". The ASA book has the same section heading.

Shawn's book does make a distinction (p. 174) but then goes on to say "Vortex ring state is a more clear, precise definition". I think that what he's saying is that you can be in a situation where you don't have enough power to maintain altitude, without necessarily getting into VRS. Though if you're HOGE with no wind (or sort-of hovering with zero airspeed) then VRS must surely rapidly follow. (And he has a footnote which says "The term [SWP] is very misleading and won't be used. I'd ask you to remove it from your vocabulary.")

[Hawkeye0001]

Nice and simply differentiation of VRS and SWP from Transport Canada (https://www.tc.gc.ca/eng/civilaviation/publications/tp9982-exercise26-973.htm):

There are some uninformed pilots [sic!] 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.
[...]
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.

[paco]

The term Power Settling is apparently the equivalent of VR - SWP is different, as mentioned.

phil

[[email protected]]

I think the 'settling with power' term is used more widely in the Americas than in UK - don't know about the rest of Europe/world.

Often the consequence of not having enough power to arrest the RoD, or even achieve the hover, is pulling past engine limits until the Nr decays which just increases the RoD. That is why SWP and VRS are often confused and SWP accidents are often given a VRS cause incorrectly.

Theoretically if you have enough power to overcome the enormous rotor drag, it should be possible to get out of VRS just using collective.

It is disc loading that determines the speed of the rotor downwash and hence the RoD required to catch up with it and encounter VRS.

I think many demonstrations of VRS are stopped at the incipient stage (probably quite wisely) to highlight the stage at which recovery should have been initiated rather than going the whole hog into full VRS.

[n5296s]

I think the 'settling with power' term is used more widely in the Americas than in UK

That could be it - all the instructors I've worked with, about 6 (all in the US), have used this term rather than VRS, though they know what VRS is. And indeed the FAA evidently uses the two terms interchangeably.

I think many demonstrations of VRS are stopped at the incipient stage (probably quite wisely)

My understanding is that a true fully developed VRS is pretty seriously scary, whereas incipient VRS is no big deal. Just like a fixed-wing spin, really. And in both cases, the only reason you'd ever get in the fully developed flavour is either because you really want to (and presumably know what you're doing), or because you just have no idea what to do at the incipient stage (in which case, you're seriously out of luck!).

Anyway thanks for all the answers, lots to think about.

[Nigel Osborn]

On learning to fly over 50 years ago, we were taught to do VRS recoveries. When the rate of decent was around 4000 to 6000 ft/min we would initiate recovery by lowering collective & pushing stick forward. When the air speed came alive we would pull the stick back & apply power to initiate a climb.

The point was made very strongly that the tail rotor hadn't stalled, only the main rotor, so if the cyclic was too sloppy & wouldn't nose down, we would put in a boot of pedal as all you wanted was airspeed & it didn't matter in which direction you were going. Worked every time!

[Outwest]

Because of this confusion in terms ( SWP / VRS ) Transport Canada requires that an ACP ask this specific question during a PPC. The FAA really makes no distinction and as mentioned uses the 2 terms interchangeably when in fact they are as different as chalk and cheese.

VRS requires 3 things to come together. A relatively high rate of decent ( most modern helicopters this is at least 500ft/min). Partial power, and airspeed less than translation. Gross weight is not a factor and actually it is easier to get into VRS at a low GW.

SWP or PS as it is also called is simply a condition which requires more power than is available for the conditions. Think loading your 206 to gross at sea level and then trying to land on a mountain at 10,000 ft on a warm day.

[[email protected]]

Gross weight is not a factor and actually it is easier to get into VRS at a low GW. It is a factor simply because it is easier to get into VRS at lower weights - low weight equals less downwash speed (less collective pitch) equals lower RoD required to catch up with the downwash.

Pilots can be lulled into a false sense of security flying a lightly loaded helicopter - they have bags of spare power and VRS is often the last thing on their mind.

Just the sort of time you might be tempted to continue with a steep approach that you would otherwise have gone around from - you've got loads of power so where's the problem - if you had been heavy, you would be more careful about your approach.

[Outwest]

You are correct Crab....actually I should have said "high gross weight is not a factor" Thanks for clarifying that...

[ShyTorque]

On learning to fly over 50 years ago, we were taught to do VRS recoveries. When the rate of decent was around 4000 to 6000 ft/sec we would initiate recovery.......


Wow! That is 3555 knots downwards.....What sort of helicopter was that? :ooh:

(Reminds me of the Specsavers advert where the bloke and his wife get on a roller coaster by mistake while he eats a cheese sandwich. What sort of cheese was that?). :E

Sorry, Nigel ;)

[Devil 49]

might have come from the preponderance of Vietnam era pilots at one time. Not at all unusual for a Huey driver to be heavy, pulling all the power the engine would make, be within limits, and still not have enough to arrest the descent. I don't recall ever hearing the term VRS at that time although we did demonstrate and teach recovery in Primary, in a TH 55.

[ShyTorque]

I was taught to recognise that as over pitching, not VRS!

[[email protected]]

It's not overpitching until the Nr decays:ok:

[ShyTorque]

Oh, but it will.... :p

[Thomas coupling]

FFS this again! I get the feeling that either modern day helicopter pilots get less and less training in these areas or FI's are more dumbed down than before and don't understand it themselves. Other than CFIT, I would argue that these two phenomenon's alone - are one of the biggest causes leading to a crash.

STILL this subject rears its ugly head. One would have thought that over the years almost all 'experienced' helo drivers are acquainted with the issues, done their own research or spoken to someone who fully understands it. Probably the best "experienced practitioners" for flirting with IVRS - are long liners and cattle musterers, who can sense these states almost instinctively if they live long enough!

For the "Nth" time and for as long as it takes to educate the lumpen proletariat, here it is all over again:

http://www.pprune.org/rotorheads/116124-vortex-ring-settling-power-merged-14.html

Go straight to post 261 by Nick Lappos who used to be Chief Test Pilot for Sikorsky. This is 'probably' the closest anyone will get to trying to illustrate the difference between VRS and SWP.

In a nutshell and K.I.S.S:

VRS: This requires a descent (usually >70% of the induced flow). It requires a LOW fwd speed and finally it requires application of power (You cannot have VRS in auto). 3 FACTORS.

SWP: Descent needed, Velocity (vertical or fwd), Application of power. 3 FACTORS.

To the ignorant (and I chose that word carefully), they appear similar. Far from it.

What then is the difference (drum roll):

VRS is an AERODYNAMIC phenomenon - it is to do with developing blade stall/induced flow/big green arrow movements/vortices.
SWP is a PERFORMANCE phenomenon - it is to do with the engine(s) NOT providing enough power to arrest the 3 defining factors.

Both require height to recover. Fully developed VRS requires 1000's of feet. Let no-one be in any doubt about that.
SWP requires a tiny fraction of this amount.

{Tail rotor effectiveness (TRE): diminished as it enters dirty air from the main rotors during VRS.}

Of course if mother earth chooses to intervene during the recovery phase............:rolleyes::rolleyes:

See you all here again in 2021......:ok:

[Variable Load]

Well done TC :ok:

[AnFI]

TC - you are right - there's a lot of junk information around including your incorrect but confident statement:

"Fully developed VRS requires 1000's of feet. Let no-one be in any doubt about that." wot no-one?

It's as bad as the ETPS story further up 4kft to recover - please, really, come on, get a grip man.

If you actually thought you were plumetting in a barely controlable helicopter in some almost impossible VR then:

In ('Fully Developped') VR with a RoD in the order of an autorotative RoD then simply lowering the lever to eliminate Positive Induced Flow and make Negative Induced Flow places you in a docile Autorotative State, the recovery from which into powered flight doesn't take more than a few 100s of feet - duh!

From fully developed VR to climb can be accomplished in better than 120ft (indicated, ie not taking account of local pressure errors due to local static pressure changes between the 2 states) - of course none of that actually has much to do with what you do about VR at say 50ft on short final - other than to impress upon the happless pilot that it is worth avoiding scenarios that lead you there.

(2 factors for VR: 1 power 2 directly opposing airflow)

[Mast Bumper]

AnFI, serious question for you:

Have you ever been in VRS that has developed past the initial phase, lowered the collective as you say is the smartest thing to do and tried to "fly out of it" but for the first few seconds nothing happens and the VSI is still pegged? You move the cyclic either far forward or off to one side but the helicopter doesn't respond to your control inputs all the while the flying brick that you are seatbelted to continues to plummet towards cumulo-granite? Have you ever experienced this?

[helmet fire]

hearing you TC, ......and it is almost time for the LTE v LTA to start up again...

:}

[Ascend Charlie]

It has already been hit on the head, asking "Why haven't the experienced pilots passed this knowledge on?"

BECAUSE.....

The instructor you are flying with has only 100 hours more than you do. He doesn't have any experience. Zip. SFA. NFI.

[Nigel Osborn]

ShyT
There's a smart one in every family! Definitely a grey hair moment, now fixed!!:ugh:

The S55/Whirlwind was great to demonstrate VRS. As you applied a little power the helicopter would shake & go into VRS ( that's if the other factors are present ) The ROD would settle about 3000 ft/MIN, apply lots more power, then the shake would increase & the ROD could get up to 6000 ft/MIN. Remove all power & out she comes, get some airspeed & climb away if required.

[[email protected]]

Oh, how refreshingly unusual - NOT!

A certain self-professed expert in all matters aviation and especially aerodynamic (yet with no visible CV) rubbishes a bunch of very experienced helicopter pilots (most of whom are well qualified instructors).

Once more the pronouncement of his theory which is supposed to trump ACTUAL experience.

Absolutely no Frickin' Idea who I mean????

[Democritus]

It's as bad as the ETPS story further up 4kft to recover - please, really, come on, get a grip man.

AnFI - so you are calling me a liar? I was there on that occasion and experienced the 4000ft to recover. With that accusation and your incessant ramblings about how two engines are unnecessary I really can't be bothered with reading any more of your drivel. Be proud that you are the only person on my ignore list as of now. PPRune suddenly becomes a better place.

[Torquetalk]

AnFI

As a few of the posts have already indicated, you are just wrong on this. It WILL take a frightening amount of height to recover from VRS in a higher mass helicopter. And autorotating out won`t fix the problem in a hurry either, because that will also be an auto with a huge ROD. In fact, the odds are that the VSI wouldn`t even indicate the real value, because it will run out of numbers.

TT

[chopjock]

And autorotating out won`t fix the problem in a hurry either

But presumably autorotating out will mean instantly no longer being in VRS.
Maybe not a full recovery anytime soon, but no longer in VRS non the same.

[Torquetalk]

Autorotating out is unlikely to have any advantage over other methods of recovery, including the method which is the subject of this thread. If you don`t have the height to recover, which aerodynamic condition you were in will be of little consolation when the ground comes up to bring events to an ugly end.

[Hughes500]

Well all I can say I have been in full VRS once, terrifying .
In a S300 had demonstrated recovery from incipient state with a ROD of 800 ft a minute to a student and let him recover 6 times. All from 3000 ft agl. Recovery was to dump lever and forward cylic.
Decided to do one last one, as a relatively young instructor had hands close to controls but not on. Had heli at 3000 ft started to go into incipient state, ac shaking pitching and rolling ROD 800 ft min asked student to recover, his action was to apply max collective......... f..k me. We were suddenly falling tail first, from seeing mother earth in a normal plain to sitting with one' s back to her in a split second is a bit of a brown trouser moment ! IVSI almost instantly went to 3000 ft a min. Lever fully down, cylic full forward nothing happening still falling tail first. Could see ground coming up to met us very quickly, applied full left pedal ( don't know why instinct maybe or nothing else left to do ), instantly from looking up at the heavens now looking straight down at mother earth!! Ac then seemed to pick up speed ( don't remember too much ) then stopped shaking, full power applied and levelled the shop at about 200 ft from ground. Student then commented would you like to punch me when we get back to the field.
As they say by the Grace of God. Cant really say I thought too much about what happened as it happened unbelievably quickly !!

[Flying Lawyer]

Crab A certain self-professed expert in all matters aviation and especially aerodynamic (yet with no visible CV) rubbishes a bunch of very experienced helicopter pilots (most of whom are well qualified instructors).


The poster is an experienced helicopter pilot (at least 30 years) and a well qualified instructor/examiner.

NB: Just for info. I don't have sufficient knowledge or experience to join the discussion.

[Thomas coupling]

In that case, I now partly understand why some of the helicopter experience pool is shallow or in this case non existent. ANFI you should be utterly ashamed of yourself, not only are you ignorant of absolute basics but you have now shouted it from the roof tops. What a sad state of affairs you have allowed yourself to deteriorate into. If FL is talking about you - you need to have a long hard look in the mirror before deciding to continue spreading this confusing rubbish you advocate - as an Instructor

Learn by rote, what Mast Bump / Democritus / NigelO stated. Pass their experiences onto as many wannabees as you can. Get them engaged and curious and then pass them onto us, so that we can teach them the correct response!
Understand that Fully developed VR (by which I describe in my musings as: "VR" (as opposed to IVR) is a state of 'uncontrol' inside the helicopter. For most pilots that means they become passengers. ANY recovery procedure (the correct one of nose down and once gaining fwd speed - raise collective) OR attempt to enter auto will depend on when the helo decides to recover (see Hughes 500 very scary (hair raising) experience). ONLY then can you 'pull out'. Until then the RCDI will remain pegged old boy and most certainly won't recover by hundreds of feet:ugh:

Please tell me you'd been drinking when you posted that ANFI? :eek:

[Helilog56]

Hughes 500's story tells it best....true VRS is pretty scary and at best unpredictable. We do on occasion put an aircraft into it to demonstrate what it is about for a student or pilot that has not experienced it.....never, ever less than 6,000 ft agl. In my 38 years of flying, it is still the only air exercise that still gets my heart rate up.....:ooh:

And Anfi.....let me know if you ever come to British Columbia.....I would be more than happy too take you out for a ride.

[Thomas coupling]

This topic is very close to my heart. I and my peers were probably one of the last to demonstrate this as part of the basic flying course (helos) in the British military (Navy). Since then Instructors have only talked about it because they had no alternative.
Hands up how many people "think" they have entered Fully Developed VRS?
As a guide let me suggest the following are prerequisites:

MASSIVE RoD (> 3-4000')
Nil or sluggish response in a minimum of two planes, probably three planes.
Vibration.

IF you don't have all three - whether you THINK you have experienced FDVR or not - guess what....you haven't!

I'm not flying any longer (had my time, done my bit), still in the trade (welded to it) but unlike most other industries the art of flying doesn't change - it is a technique which cannot be shaped to fit in with modern ideals. Subsequently it is what it is.
By this I mean that provided you get a grip of some basic techniques early, you can safeguard that which is most precious (your life) for decades to come :uhoh:
All qualified pilots have ticked most of the training boxes to enable them to fly off into the future and survive most occasions when things get tough, but with an extra amount of effort, research and preparation you could reduce the risk of harm to you and your passengers to an absolute minimum.

Ask yourself this - "Am I conversant and confident about the following helicopter traits that 'may' visit me during my career:"

IVRS
VRS
SWP
PS
LTE
LTA
Tail rotor malfunctions
Ground resonance
Ground loop

(None of the above can be adequately practiced outside of a simulator)

If you (a) understand each one, (b) have a response ready for each one....then you have risk managed your future to the best of your ability. That is a sign of a true professional and no-one can ask more of you.
IF you 'think' you understand these but are not sure - go find someone like many very wise guys on this fantastic forum and talk to them either online or PM them if you don't want to be embarrassed in public. Don't continue in the dark - it might go dark sooner than you think........and forever:\

Fly safe and keep the damn ball in the middle..............................

[Lonewolf_50]

TC: I would hope that a few of the posts on this topic are stickeyed by the Mods, your last included.

I'll raise my hand as one who never ever wanted to experience VRS, and who approached the maneuvers where it was likely (usually some kind of steep approach to a confined area, with a go-no-go point and an escape route already selected. They taught us during my training that we need to avoid it as if our life depends on it.

[[email protected]]

TC - :ok:

Oh dear AnFI - no wonder you have tried to keep your identity a secret - here's hoping FL will properly 'out' you so your students can discover what guff their instructor has been spouting.

FL The poster is an experienced helicopter pilot (at least 30 years) and a well qualified instructor/examiner. what has he been teaching and to whom? Has it just been basic PPL/CPL flying or has he actually been operating a helicopter out in the real world?

[Senior Pilot]

AnFI has not been online since his last post, and will not be contributing further to this thread. As one who was taught and shown developed VRS during training I share the views of others and will not have AnFI tout his bizarre concepts here, regardless of his background.

[MightyGem]

FL
Quote:
The poster is an experienced helicopter pilot (at least 30 years) and a well qualified instructor/examiner.
what has he been teaching and to whom? Has it just been basic PPL/CPL flying or has he actually been operating a helicopter out in the real world?
I thought that perhaps FL's comment was referring to TC as he had thought that your comment:
A certain self-professed expert in all matters aviation and especially aerodynamic (yet with no visible CV) rubbishes a bunch of very experienced helicopter pilots (most of whom are well qualified instructors).
was also referring to TC.

Of course, I could be wrong.

[Thomas coupling]

Mighty (good evening to you), it's late and I notice that the quote from FL has been 'modified' - the last bit is missing from his original post??
Secondly - I'm tired, can't think straight (quiet Crab!) what exactly do you mean?:zzz:

[busdriver02]

Teaching VRS to student pilots is crazy. That **** should be for test pilots only. You older types were off your rocker back in the day!

I always thought this chart was a good visual depiction of the required parameters: Link (http://www.copters.com/aero/pictures/Fig_2-82.gif).

[Flying Lawyer]

I responded to Crab's post #34.

AnFi is an experienced helicopter pilot (at least 30 years) and a well qualified instructor/examiner.

[Mast Bumper]

Busdriver, I don't agree. Every helicopter pilot should be demonstrated what it looks/feels like when a helicopter enters the early stage of VRS and the various recovery methods. This doesn't mean that every pilot needs to go full retard and wait to recover until the vsi is pegged, but we all should have enough experience to recognize the onset of VRS and also know how to get out of it.

[[email protected]]

It is worth highlighting that fully developed VRS was historically taught because it was much easier to get into in older helicopters than it is now and simulator technology was very basic.

Back when engines weren't very powerful, rotor discs were bigger and downwash speeds were much lower so it was much easier to get to the sort of RoD where you started to catch up with your downwash.

The standard avoidance figures for VRS - keep the RoD below 500 ft/min when speed is less than 30 kts - were probably far more relevant back in the 50s and 60s when helicopter disc loadings were small.

Unfortunately the teachings haven't moved on with the increases in technology, power and performance of modern helicopters.

For most modern helos I think VRS is now best taught in a simulator, but the old criteria (30 kts/500'/min) needs to be updated when programming the sim.

However in a very light helo (R22 and the like) it is still worth demonstrating the incipient stages of VRS and the recovery so that student will learn to recognise and avoid the preconditions for the phenomenon.

[busdriver02]

Onset warning signs, especially in a lighter helo, I'll concede it's not really insane. I don't think it's strictly necessary however. I haven't had a problem avoiding VRS over the past ten years and it was not demoed to me during pilot training.

[Torquetalk]

Well that was a grave oversight in your training. It is part of the JAR/EASA syllabus and FAA syllabus. No offence intended, I just find that astonishing.

Can VRS be sim programmed?

[n5296s]

Onset warning signs, especially in a lighter helo, I'll concede it's not really insane. I don't think it's strictly necessary however.
I'm not in a position to disagree with anyone on here, but I can say that it (incipient VRS) happened to me for real, not as practice. An R44, a bit below gross (three people, half fuel), warm but not hot day, HOGE at 1000 MSL. It was taking noticeably more power than in other R44s I've flown and I'm pretty sure something must somehow be set up wrong on that particular aircraft (though it does have glass panel and pop-out floats).

Anyway... the point is that given the training that I did receive, and seeing where the power was, I was spring-loaded for it to happen, so when it did, no big deal. But we were nearly 200 feet lower afterwards, so it might have been a bit more serious if we'd been at 190 feet instead of 1000.

Practising fully developed VRS would be another matter. It's a bit like practising 6 turn spins. Can be interesting and even fun, but has nothing to do with basic flying skills (imo).

[Thomas coupling]

It's the dumbing down syndrome. Happens everywhere.
Modern jetliners where the pilots can't even spell spin and stall never mind do them. Air France losing their last crash because of it.
Modern day pilots aren't pilots they are systems managers. I hear some airlines give their crews some 'real flying practice' occasionally to remind them what it's like to "FLY" an aircraft.
When I joined the RN in '77....we did demo VRS, EOL's from 50'/120kts, double engine off landings, Jack stall, aeros in a helo. None of this is taught now, not one bit. People only talk about that list I gave out earlier.
I often wonder whether the Strathclyde crash was a symptom of some of the above but with a twist. We shall learn soon (I hear the AAIB have completed their findings and are in discussion with relatives before they go to press).
And all of the above was in the military - God only knows what civvy helo pilots are being taught these days!!!:\
SDSR 2010 (mil defence review) attempted to assuage the critics by directing that 25% of all mil training would be in the simulator by 2015 and 50% by 2020. The conversion to SAR S92 glass cockpit is >90% simulator.
Better than nothing I suppose - at least it addresses each of these helo orientated aerodynamic issues. How many civvy pilots (GA) use a sim, I ask?

It's good to read feedback from people like N5296 and mastbumper who have respect for these 'gottcha's. I worry about people like Busdriver02 (nearly called him a pilot then :eek:) who have complete contempt for the very subject matter.

Let's hope the former are in the majority.

[ShyTorque]

I often wonder whether the Strathclyde crash was a symptom of some of the above but with a twist. We shall learn soon (I hear the AAIB have completed their findings and are in discussion with relatives before they go to press).The (ex RAF) captain of that aircraft would have trained on the Gazelle at a time when the the syllabus would have been similar to the one you describe. Or, at least, it was when I instructed in that role at Shawbury in the mid 1980s.

But not aerobatics, because iirc, they were prohibited, being outside the terms of the flight manual.

[Thomas coupling]

Hi ShyTorque.

We both knew the pilot of the Strathclyde crash. I don't want to divert this thread nor do I want to cast ANY shadow over his exemplary and distinguished record. I qualified my last post with the word "twist" because many of the skills required of an aviator - are perishable over time unless they are constantly practiced.. Many many years will have past since doing one's last (single engine off) in a Gaz piece and (allegedly) losing both engines in one's twin at night.

Aeros were off limits to 'most' Gaz pilots those days.............................but not all ;)

[ShyTorque]

Aeros were of limits to 'most' Gaz pilots those days.............................but not all ;)With the approval of the manufacturer, and the service, as an ex helicopter display pilot, I'd have no objections either. But nothing to do with VRS.

Every pilot of a twin should get to practice entry into autorotation, though, at least annually, during the OPC/LPC.

[cattletruck]

Incipient VRS was demonstrated to me and I found it was very easy to get out of. I was told and left to believe that, like low RRPM, if left unchecked you will die, simples.

I have no reason to question the wisdom of my instructor on this matter. I'd imaging fully developed VRS in training does cause wear and tear on your machine and carries unnecessary risk - thanks Hughes500 for sharing your story, incipient VRS is as far as I would ever want to go.

[busdriver02]

Torquetalk,

Given the mis-understanding between VRS/SWP/Power Settling, etc. I'd say it isn't being taught correctly many places. It was discussed, I'd say more time was spent on tail rotor effectiveness. But the rate of descent needed to teach that in a UH-1 is pretty silly when the other hand is telling the student not to exceed 800fpm (can't remember if we used the 500fpm ROT back then) on the approach.

I don't see why it couldn't be put into a SIM, the old Huey sim at Rucker would simulate a loss of tail rotor gearbox. That was a rough ride.

I think crab said it better. I'll admit having the lightest helo a pilot has ever flown be a UH-1 isn't the norm around the world either.

[Hughes500]

I still teach incipient vrs and in particular the areas where it is most likely to happen i.e. downwind landings and low and slow aerial photography going round and round a target
It is absolutely essential that it is taught. I show students that in a 300 and 500 that the machines vibrate when losing translational lift I remind a student to check their vertical speed as the onset of this rumble if more than 500ft a min think about going round ! One can have a 500ft vertical descent in either machine with less than 20 its and pull collective and it will climb. Get that to 700 to 800 ft and I start breaking into a sweat and have my body weight poised over the collective ( i am 100kgs ) in case the lever is unexpectedly pulled up !
People are right the standard of training is woeful everyone seems to concentrate on pointless exercises such as Vor tracking for instance and not on the more important things !

[busdriver02]

Hughes500, All of that sounds perfectly reasonable and isn't any different really than the way I was taught. But do you take your student out intentionally setup in your case an 800fpm descent below ETL and then add collective? I guess that's what I envisioned when guys said they "taught" VRS.

[Tourist]

TC

The RN was still teaching your list of fun stuff when I went through in the 90s, plus annual VRS reminder in the Seaking. I fondly remember the out of control falling sensation....


That all said, can any of the wise heads here tell me why fully lowering the lever doesn't instantly take you out of VRS?
You should be clear of the vortex almost instantly, surely?

Just to be clear, I know it doesn't work quite like that, I just want to know why.

[Hughes500]

Busdriver

I certainly do but putting into incipient vrs is fine, I describe it to the student as the helicopter not wanting to fly ( the whole airframe is shuddering through the base of your seat as opposed to vibrating through the controls ) at this point stick the cylic forward, as soon as the ac stops shuddering apply full power and maintain fwd cyclic to climb away( as the nose will violent rise with full power ). I am trying to teach " muscle memory " I know you might not require full power but prefer to teach that and then slacken power rather than the other way. Bear in mind the average private guy takes no or little continuation training so really have to drum it in !

[jymil]

Back to the original topic of the thread: the whole point of the "Vuichard" recovery technique is to get out of a vortex in situations where you don't have sufficient altitude for a standard recovery (i.e. lower collective and pick up speed before you raise collective again). This can be applicable e.g. when long lining and in this situation you should have HOGE power (i.e. you're not settling because you have insufficient power).

[Dynamic Roller]

That all said, can any of the wise heads here tell me why fully lowering the lever doesn't instantly take you out of VRS?
You should be clear of the vortex almost instantly, surely?

Just to be clear, I know it doesn't work quite like that, I just want to know why.

Not a wise head by any stretch, but here is what I think.
Yes, fully lowering the lever will instantly get you out of VRS (and into an auto), but your ROD and inertia at that point can be quite significant, to the tune of thousands of fpm in the extreme.
So even if forward speed is quickly gained at that point, you'd still need to arrest the high ROD, and near the ground, where inadvertent VRS is most likely, there is not a lot of cushion for that. Even if normal auto ROD is less than 2000 fpm, the VRS ROD can be much greater, and being in auto doesn't instantly reduce the ROD.

[busdriver02]

Fair enough, I suppose my frame of reference is stuck in a helicopter that would require something like 1500fpm to get into that regime.

On topic, is this technique based on shortest distance to get out of the vortices? Why would this take less altitude than nosing over? I suspect most folks aren't comfortable putting the nose down 20 degrees, but are perfectly happy with 20 degrees of bank.

[Mast Bumper]

Jymil, you're absolutely correct. I learned this recovery technique a long time ago while flying a longline. After a bit of practice, the recovery maneuver can be done quickly and without much drama.

[[email protected]]

busdriver - I think the point of this technique is that in full VRS, cyclic response can be erratic and sluggish, whereas the TR should be clear of any vortex.

[Thomas coupling]

Crab: Morning to you, hope you're enjoying your new job!
I'm moving on also......still aviation.

WRT your last comments: don't forget - in FDVRS the tail rotor could and can get caught up in dirty air from the main rotor. ALSO as and when Nr decays during VRS, this drags the TRE by a disproportionate amount thus reducing its effectiveness even more.
Do not rely on the TR helping anyone out during VRS :uhoh:

This so called " Vuichard Recovery Technique" seems only to be relevant to recovery during Settling with power and not FDVRS, I would suggest...............

The last thing one would want to do during VRS is to pull FULL collective power :ugh::ugh:

[mdovey]

Are there any references to the Vuichard technique in particular how\why it is suppose to work?

The only reference I could find googling is the wikipedia article (or direct quotations from it), and let's face it neither wikipedia (nor anonymous forum posts!) are necessarily reliable sources of information.

The wikipedia article suggests the technique is described in the 2013 R22\R44 Flight Training Guide (which looks like it is only available in hard copy from Robinson).

Matthew

[[email protected]]

TC - congrats on the new job - do pm me with details.

Very happy in my new role:ok:

I think this technique is only suitable for VRS, definitely not for SWP as you are already decaying the Nr as you overpitch which, as you say, degrades TR thrust markedly.

I know yaw variations can be a theme of VRS due to the 'bursting bubble' disruptions from the MR upwash and, in this case, the TR would be less effective.

However, not every episode of VRS will give those symptoms and it will vary with aircraft type. Equally not every excursion into FDVRS will give Nr decay - that will only happen if you keep pulling until you hit engine limits.

It may be that this technique has some validity in some circumstances and it certainly can't make things worse if you are limited on recovery height available.

[n5296s]

Are there any references to the Vuichard technique in particular how\why it is suppose to work?

The only reference I could find googling is the wikipedia article

The wikipedia article suggests the technique is described in the 2013 R22\R44 Flight Training Guide (which looks like it is only available in hard copy from Robinson).


One question I CAN answer since I started the thread... the only place I've seen is the Wiki article and some things that quote it. It came up because the friend who was with me when it happened - who is also a fixed wing & autogyro pilot and very curious about things in general - looked around and I guess found the Wiki article.

It certainly isn't described in the R44 POH, which I have at home.

[Devil 49]

"WRT your last comments: don't forget - in FDVRS the tail rotor could and can get caught up in dirty air from the main rotor. ALSO as and when Nr decays during VRS, this drags the TRE by a disproportionate amount thus reducing its effectiveness even more.
Do not rely on the TR helping anyone out during VRS

This so called " Vuichard Recovery Technique" seems only to be relevant to recovery during Settling with power and not FDVRS, I would suggest...............

The last thing one would want to do during VRS is to pull FULL collective power."

Interesting thoughts, TC. If the tail rotor thrust and anti-torque were compromised then I think the expected torque effect yaw would present. If not, I would expect that the TR was still effective and might be helpful in slipping the aircraft into 'clean air' without the considerable loss of altitude with the conventional recovery. I do wonder what advantage the described technique offers to just putting the nose down.
I share your apprehension at increasing power in VRS situation.

[gator2]

A couple of thoughts on this from a 200 hr pilot, (but an engineer).
When full lever down, lift is still created by the rotor. As proved in my R44 with a solo auto, cold day, little fuel, full down lever still doesn't drive rpms into green, and the whole auto can be performed with the lever down.


Therefore, lift is still being created at full lever down, therefore downwash is still being created, therefore downwash is still being added to the VR column even as we pray for the machine to drop through that column.


When the cyclic is rammed forward and not much happens, it is because we're still roughly at the speed of the downwash, so not much of a horizontal vector is created because not much "felt" by the rotor disk.
s
So, fully developed VRS, drop the lever, ram the cyclic forward, you have to wait for the machine to drop THROUGH the downward column of air, which it is still adding to somewhat, or hope what little horizontal vector you can put on the disk will pull the machine forward out of the column.


On the other hand, if the tail rotor is outside the column of air going down, it can add significant translational force to the right ('Murican helis), while crossing the controls adds to that translation to the right with whatever horizontal vector the rotor disk can bite out of the downward column. Sidestep 40 feet to the right, and viola! Clean air. So, in theory, that seems to me the underlying cause that the vuichard technique might be quicker.


Or not. I'm just a rookie.

[busdriver02]

Why I went the way I did:

Tail rotor effectiveness or not, unless I'm missing something accelerating the airflow over the disc is key. Just booting the tail out wouldn't cause an acceleration. Given it's supposed reference in the R22 manual (wiki source, I have no truth data) it seems more a link to getting the disc tilted rapidly without getting negative G and the associated mast bumping problem. If I were concerned with mast bumping and felt the onset of VRS, I could make a faster recovery with this technique just based on time to get to say 20 degrees of tilt. I guess I fail to see what cross controlling does different than shoving the nose into the dirt. Both rely on having some level of cyclic control remaining, just a different axis.

Not trying to be a snarky smart ass, I swear.

[gator2]

Well, I think that is why you apply full right cyclic with power pedal. If it was just power pedal you'd get mainly yaw. But with power pedal and cyclic you get translation. If the cyclic is full forward, or full right, you get the same horizontal vector. In fully developed VRS, not much. But, add in the full power pedal and you get the sum of the two horizontal vectors, and by pulling full power you lessen the tendency to yaw as you boot in full pedal so the tail rotor is fighting the engine and all that hp is pushing everything to the right.

[busdriver02]

Any way you cut it, I think accelerating at 1G in a helo is the realm of gravity only. I seriously doubt tail rotor thrust will make a significant impact. I have some experience trying to teach high angle strafe to AF guys/gals. They almost universally are not comfortable putting the nose 20-30 degrees down at first. All of them are perfectly fine banking the same number of degrees.

[gator2]

Get into OGE. Go full up on collective, full left pedal. Don't move the cyclic. How long does it take you to move 40 feet off center? In theory, that's the incremental movement of machine vs column you get from vuichard vs just shoving the cyclic forward.


ummmm. You first.


Like I said, I'm just a rookie. And, I can only afford to fly the much maligned Robbies.


But, for what it's worth, when I got my ticket 2 years ago my instructor did spend time with me in FDVRS. I'm not afraid to shove the cyclic as far forwards as it would go, and I did, and nothing happened for what seemed like forever. We just kept going down. And this VRS demo, which he has repeated with me a couple of times since as I do reccurency, is the only time he's up on the edge of his seat, hand hovering over the lever, looking pretty worried.


I won't be testing my understanding of this theory, or betting anything on it, in the future. But, it's a good thing to have in the back of my head if I'm stupid and inattentive enough to get past incipient VRS, can't get out of it, and have nothing left to try. And I never intend or have to do that because I'm not only a rookie, I'm an amateur. Peace out.

[Thomas coupling]

Going back to the OP who begins with a quote for a techinque to address settling with power:
Another recovery technique is called the Vuichard Recovery Technique: initiate the recovery by increasing the collective to takeoff power, then simultaneously applying power pedal to maintain heading and opposite cyclic (15-20 degree bank) cross controls to get lateral movement. As soon as the rotor disc reaches the upwind part of the vortex the recovery is completed. Average loss of altitude during the recovery is 20-50 ft depending on the duration of the recovery procedure. .
The message that needs to be out there is that IT IS THE WRONG TECHNIQUE for recovering from either IVRS or VRS.
It is bad enough trying to pronounce this guys name never mind trying to remember whether to PULL power or LOWER the lever.
[Although - technically in VERY powerful turbine engined helos - there is a case for removing oneself from VRS using 'application of power'].
In MOST cases, when in VRS, the following is observed:
Vibration.
Sloppy feedback response in the controls.
Pitching, rolling and yawing to some extent.
Blade slapping.

Recovery technique for VRS:
Select smooth (do not "ram") and progressive nose fwd using cyclic to around 20 degrees n/d.
As the a/c departs the turbulent VR, controls become more responsive.
Feed in collective power to minimise height loss. (Usually >8kt fwd speed).

VRS requires most helo's to be in a RoD of around 800 - 2500 feet per minute. Anything greater than this is due to the a/c simply 'falling' out of the sky. In fact, >2500fpm pushes the descending helo out of the VR.

WHILST IN A VRS DO NOT RAISE THE COLLECTIVE -it will aggravate the VRS.

http://www.pprune.org/rotorheads/116124-vortex-ring-settling-power-merged-3.html
refers (post 51+)

Quote from N Lappos:

During VRS, typical modern helicopters retain some cyclic control. The rate of descent will make the horizontal tail try to pitch the nose down, which will help you recover. Reduced collective and nose down will produce a fast exit from VRS. Increased collective will only help if the aircraft has a great deal of excess power, not at all likely in anything but an empty machine with powerful turbine engines.

Note from the data on the web site that VRS is unlikely in a purely vertical descent, some forward speed is needed, maybe 8 knots. In practice, it is difficult to attain and hold VRS, as the condition is unsteady and tends to break of its own if any disturbence is induced. That does not mean it can't do harm, since the first 1000 feet of drop might be several hundred feet too many! .

Please make sure you are 100% certain you know how to avoid VRS in the first instance (IE: Identify IVRS early and recover with N/d and power ).
IF you are unfortunate to find yourself in fully developed VRS (and you have the height beneath you to recover) - select >20 degrees n/d, check down on collective, clear the VR, then and only then pull power.:ok:

[[email protected]]

So Monsieur Vuichard, whoever and wherever you may be, it seems your 'technique' has been sent to room 101, never to see the light of day again.

It might have been an interesting idea if it wasn't for the 'apply full power' part which, as TC has highlighted will just make things worse in VRS and, since the definition of SWP is that you don't have any power left, is pointless when dealing with SWP.

Since modern rotor systems with bigger hinge offsets retain control power much better than teetering heads, it is possible that the lateral cyclic might help, but no more than forward cyclic will.

Application of pedal may or may not be effective but not as effective as pushing the nose down.

Short answer - stick to the basics as described by TC and others.

[jymil]

This recovery technique has been proven to be working during official test flights for the Swiss CAA. You can inquire more information from Mr Vuichard directly if you want, his contact data are available in the Swiss CAAs helicopter examiner list:
FOCA - Examiners for pilot examinations (http://www.bazl.admin.ch/experten/ausbildung_lizenzen/03160/03161/03620/03670/index.html?lang=en)


The whole point is: this technique can save lives, e.g. the 4 people which got killed by the CHC crash in 2013. And it is counter-intuitive, because we were all taught pulling collective up during VRS is wrong, as Thomas coupling reiterated. However, it does work because you can get out quickly of the vortex column into undisturbed air left or right of you by applying a 20 degree bank.

[[email protected]]

This recovery technique has been proven to be working during official test flights for the Swiss CAA Any data to support this? test configuration, aircraft type, AUM, IAS, RoD?

Seems strange that only the Swiss advocate this method or is it wider spread than that?

The CHC crash would not have been avoided using this technique - you have to recognise you are in VRS first. There were a whole lot of other factors which could have prevented it.

[mdovey]

It certainly isn't described in the R44 POH, which I have at home.


The wikipedia article says it is in the (2013 edition) R22\R44 Flight Training Guide (FTG), which is the fifth manual listed at Robinson Helicopter Co. (http://www.robinsonheli.com/manual.html)

Whilst, I can find html versions of all the POH's Robinson website (and it isn't in those), there doesn't appear to be a html version of the FTG and I don't have access to a hard copy.

[n5296s]

Seems strange that only the Swiss advocate this method or is it wider spread than that?
Maybe it's because they have a different relationship with the holes in the cheese?

(Sorry, couldn't help it. And thanks for all the contributions to this thread, it's all quite amazing actually - and also the reference to the ancient (by Internet standards) contributions by Nick Lappos et al).

There seem to be a lot of parallels between FDVRS and fully developed fixed-wing spins. They both have a fairly simple aerodynamic explanation, on the face of it. They both behave predictably about 95% of the time, so you're not really prepared for the 20th time when it turns around and bites. And it's only when you get into deeper analysis of exactly what is going on that you realise just how complex the whole thing it is.

From a pilot training pov, there's no reason ever to be in either, just to know what causes it and to recognise the onset so you can NEVER go there. (That said, I've done a lot more spins than I ever intend to do FDVRS, for which my target is zero unless one day I'm lucky enough to fly with one of the handful of people who could safely demonstrate one).

Thanks again for all the quality input and reflection on here...

John

[Peter-RB]

A random Question Not an excuse to Take me out at Dawn.!! :eek:

Would VRS and or Ivrs be the fixed wing equivalent of a Full stall ?

Now moved away from the screen, to watch from a safe distance..!

Peter-RB :ooh:

[FH1100 Pilot]

It's all well and good to talk about theoreticals like how many thousands of feet it takes to recover from FDVRS. But it doesn't really matter. Conditions like VRS and SWP do not typically occur up at altitude where the hapless pilot has plenty of time and altitude to figure out what's happening. No, these things usually happen down low, at the bottom of a mucked-up approach. And then it's over pretty quickly. BAM! as Emeril Lagasse would say.

Using the Sr. Vuichard's method might work for a VRS encounter (although I personally have not yet tried it). But what would happen if you were just running out of power to stop an increasing rate of descent? You feed in a bunch of right cyclic and push the left pedal...and...you hit the ground sideways.

Remember, there's not a lot of time to sort things out. Either way, it'll probably be over before you know it.

Then there's the feelings of panic, denial and the resultant "this can't be happening" inaction. Even just a couple of seconds of that can mean the difference between saving the day and crashing. Oh, we all like to think we're some magic combination of the Chucks: Yeager and Aaron, but sadly we pilots can sometimes be very, very human. I know I can. And my name ain't Chuck.

And anyway, why are we even discussing this? Are helicopters still crashing due to VRS?

[jymil]

Any data to support this? test configuration, aircraft type, AUM, IAS, RoD?
Aircraft was an AS350, that's all I know. But again: feel free to contact Mr Vuichard directly yourself, I'm pretty sure he can give you all those details.

The CHC crash would not have been avoided using this technique - you have to recognise you are in VRS first. There were a whole lot of other factors which could have prevented it.

Sure, this is all speculation at the end. But from what I read, it kind of fits the scenario in my opinion:

There was then a second automated call of "check height" followed by a "100 feet" automated call. The report stated: "At some point the commander saw the sea, but he was unable to arrest the helicopter's descent and it struck the water shortly thereafter.

So the pilots didn't have much altitude left, certainly not enough for doing a standard vortex recovery.

[Thomas coupling]

Why should Britain tremble..............................................:ugh:

[busdriver02]

Well between TC's rather definitive response, FH's astute point about altitude and rolling the aircraft while crashing, and I totally missed the increase in collective part of the original post; I'm done exploring this on an academic level. It was fun gents, thanks for letting me play.

[dammyneckhurts]

I have spent most of my 11,000 ish hours looking down a longline, flying in the mountains in Western Canada. In my world we work upwind, downwind, uphill, downhill and nasty combinations of downwind and downhill. We work in a "Production based" environment and we get very accustomed to working in conditions that are conducive VRS.

When VRS happens close to the ground it's usually immediately following a power increase and the first thing you will feel is that you ass gets lighter in the seat. You will feel lightness in the seat way before you feel rotor vibration or sloppiness in the controls. Usually when you add power your ass gets heavier in the seat... if you pull the collective and you get lighter you need to take corrective action immediately.

[MightyGem]

The last thing one would want to do during VRS is to pull FULL collective power."
Obviously not for "normal" helicopters, but can't those with excessive amounts of power(an unladen UH60, for example), power themselves out of VR?

[ShyTorque]

MG, I wouldn't rely on trying to power out of VRS. When I experienced it, albeit in a Puma rather than a Blackhawk, we were just about at max continuous power when the aircraft entered (the HP was trying to achieve an OGE hover at high altitude in the dark). The rate of descent was very impressive and we lost a lot of altitude during the event.

Thinking about this, an analogy is having a powerful car at full throttle but having wheel spin and little traction.

[Vertical Freedom]

Tried the Vuichard technique & it's complete bollocks :yuk: firstly in settling with power (SWP) there is no emergency & recovery is to pull more power (if You have extra) or just pole forward.......end of story :8 If in IVRS or VRS, in my humble opinion; simply pole forward, as the shake/rattle/roll dissipates apply more power to climb away ;)

If it ain't broke...............don't try & fix it!!! :}

[MightyGem]

MG, I wouldn't rely on trying to power out of VRS.
I wouldn't, but I'm pretty sure that Nick Lappos mentioned it in one of his posts on the subject.

[jymil]

can't those with excessive amounts of power(an unladen UH60, for example), power themselves out of VR?

No, because power is actually a factor causing the problem. In the vortex ring state, the helicopter is trapped in a recirulation of its own wake. The more power you apply, the faster the recirulation goes and the faster you sink.

However, the point many people seem to miss here is that the vortex ring does not only consist of a downdraft, but also an updraft and the core idea of the Vuichard recovery technique is to use the updraft to get out of the vortex as quickly as possible.

It this wouldn't work, then Tim Tucker wouldn't have put it in the Robinson Flight Training guide.

If it ain't broke... don't try & fix it
Well, it is "broke" as long as we see unnecessary VRS accidents happen, the latest just being the Rega A109 crash last month.

[Vertical Freedom]

If it ain't broke... don't try & fix it Hey jymil

I meant the recovery technique, works no need to reinvent the wheel. :8 If someone is (still) getting into VRS & crashing then they don't understand the causes of entering VRS & blindly bumbling on oblivious :* It's there flying technique that needs adjustment & not the recovery technique :ok:

Happy Happy avoid VRS :)

[Nigel Osborn]

With older type helicopters with limited max power, in VRS pulling more power did increase the ROD. However when the Wessex 5 came on line, especially at low weights, by pulling max power it would blast its way our of VRS & climb. Do that in a Whirlwind & big trouble!

A few years ago a Puma 330 made a steep slow night descent to a ship & got into VRS. From 500 feet to splash was about 15 seconds & that's with 2 experienced Puma instructors on board! Luckily both survived.

[n5296s]

I flew the R44 again today (a different one, no floats or glass panel). My instructor hadn't heard of the Vuichard technique by name, but when I explained it, he said, "we've just started teaching something very similar". Just using right cyclic to slide out of the VRS, no pedal. We tried it, it certainly works (for incipient VRS, not the fully developed beast) - whether it works faster/better than forward cyclic is hard to say.

[Lonewolf_50]

Just using right cyclic to slide out of the VRS, no pedal. We tried it, it certainly works (for incipient VRS, not the fully developed beast) - whether it works faster/better than forward cyclic is hard to say. Between the point you make there, and the post by dammyneckhurts, the takeaway is "catch it early and recover" to avoid it getting worse ... regardless of your recovery technique.

[Devil 49]

Recently flew with a utility guy who also instructs. discussing VRS, he argued that most pilots will encounter it at low altitude, so conventional rcovery is problematic. Utility is frequently in that low/slow/high power, so often tried alternates. His point was get out of the VRS losing as little altitude as possible, lateral cyclic, that's it.
On my expressing doubt, we did a full VRS, conventional recovery, lots of altitude lost, perhaps a couple thousand feet.
Repeat maneuver, VRS, right cyclic and almost immediate recovery. Jaw drop. I can't say that the VRS was as fully developed the second time...
Explanation offered was that maneuvering laterally adds airspeed, but unlike reducing power and nosing down, the lateral move gets you into a normal airflow with minimal altitude loss.

[AlfonsoBonzo]

Same here. Just tried it last month for the first time and it works

[Vertical Freedom]

Why not just pole forward? :8

[BOBAKAT]

:ok::D I do....

[Helitin]

Rotor & Wing Magazine :: Flying Through the Vortex (http://www.aviationtoday.com/rw/personal-corporate/personal-ac/Flying-Through-the-Vortex_85872.html)

[[email protected]]

Still yet to be convinced that this technique works in fully developed VRS any better than the conventional recovery.

How did Mr Vuichard get into VRS so often that he needed to develop a 'new' technique for recovery from it?

Lets see some empirical testing with proper criteria for entry, steady state (if that can be described as steady) VRS and then a comparison of recovery techniques.

The big danger with this technique is that it will lull pilots into a false sense of security that they can push their RoD limits at low speed and altitude believing they have a magic bullet of a recovery to save them if they screw it up.

As ever - avoidance of VRS is the real skill of a helicopter pilot, not the recovery from it.

[Reely340]

suggestion (for side cyclic instead fwd.): rotational inertia

A helicopter requires much less force to turn around its longitudinal axis (a.k.a. roll) than around its vertical (yaw) or lateral (pitch) axis.
(Only in part due to the horizontal stabilizer, it's mainly a question of mean distance of affected mass from the rotational axis)

Proof: grab your household broom and
first twist it 90° along its broomstick's axis
then twist it 90° perpendicular to said axis (watch out for your ceiling lamps).
If undecided remove brush and repeat with the stick alone.

Thus if we want to redirect rotor downwash away from our VRS descend path
rolling the ac might work much faster than pitching.

[mdovey]

How effective is this technique in an ac with a fenestron TR?

From the description, the lateral thrust produced by the tail rotor is an important factor of this recovery. A fenestron has different characteristics to a TR, and also the tail of of a fenestron equipped ac will act as a blade which would(?) oppose any lateral thrust more than a traditional TR ac.

I can't see any references to using this technique in any other aircraft than a R22\R44.

Matthew

[[email protected]]

Reely - that might be an issue in a rotor system with limited control power - eg teetering head (or close to) on R22 but anything with even a slight hinge offset will have control power to spare.

Also, any helo with a horizontal stabiliser will have natural nose-down pitch in a low speed descent.

[Lonewolf_50]

suggestion (for side cyclic instead fwd.): rotational inertia

A helicopter requires much less force to turn around its longitudinal axis (a.k.a. roll) than around its vertical (yaw) or lateral (pitch) axis.
(Only in part due to the horizontal stabilizer, it's mainly a question of mean distance of affected mass from the rotational axis)

Proof: grab your household broom and
first twist it 90° along its broomstick's axis
then twist it 90° perpendicular to said axis (watch out for your ceiling lamps).
If undecided remove brush and repeat with the stick alone.

Thus if we want to redirect rotor downwash away from our VRS descend path
rolling the ac might work much faster than pitching.That's a good point, but there is also the inertia of the entire mass of the aircraft with its load moving in the direction of intended flight. The lift vector (when changed in the direction of lateral movement) has to overcome that ... and is doing so (if one is actually entering VRS or in it) with a less effective "bite" into the air. As I've not flown Robinsons, no further ideas.

[maddmatt]

My first FI, a veteran of 2 wars, would frequently tell me that while training for emergency procedures were necessary, the fundamental approach was not to get the helicopter into a situation that led to you needing to implement those procedures. Obviously he was referring to thing like VRS, SWP etc but his advice has stuck with me.

[Chucklehead]

I stumbled upon this article describing an alternate way of getting out of vortex ring state. The conventional recovery I've been taught is to reduce collective and establish forward airspeed. The article suggests applying left pedal, right cyclic and cruise torque to fly out with minimal altitude loss (on a CCW rotor system).

Anyone had experience utilizing this type of recovery? For some reason I find it difficult to believe that no one's considered sideward cyclic application before, but the idea seems to make sense. Link below:

Aviation Today (http://www.aviationtoday.com/mobile/getitem.php?item=85872)

Thanks!

Edit: forgot to search before asking... Sorry folks!

[Gordy]

See here:

http://www.pprune.org/rotorheads/557861-vuichard-technique-settling-power.html

[Vertical Freedom]

You need (again) air speed, so then; why pole Left or Right to recover to only again need to pole forward to regain critical speed? 'if it ain't broke, don't fix it" The old basics of pole forward for air-speed whilst leaving power ON, is the fastest & most effective recovery from VR & regain a Safe Flight configuration :8

[TIMTS]

You can't always "pole forward"...approach to elevated pad etc. Always nice to have another trick in the bag. I was taught this by Bristow back in '07, to avoid smashing into a deck offshore should you get into vortex ring state on short final. So it's hardly a new trick at all.

[Vertical Freedom]

Hey TIMTS, yep good point, similar to making a confined mountain pad approach with no way out forward or to the side........so approach in a way to avoid the risk of VR, yep it's another technique that in a confined I'd use :ok: actually in 30 years only had it once whilst HOGEing for a film shoot when I over flew an area of massive updraft which inducing VR & not ROD :eek: but I had somewhere to pole forward too, so walked away on wobbly legs :hmm:

Happy Landings :cool:

[jymil]

@VR
You need (again) air speed

That is not correct (assuming you have HOGE power). All you need is to get into undisturbed air which doesn't exert a downward force on you through recirculation.

[Vertical Freedom]

Hey jyml; so the Vuichard stops the VR, great news & now You have now airspeed & a high rate of descent & then.......the circle begins again; VR due high rate of descent, no airspeed & power on hmmmmmmm :ouch:

[jymil]

Seems as if you have a misconception of the procedure somehow. The rate of descent is quickly stopped to zero, so you cannot get into another vortex.

This might also help:
Rotor & Wing Magazine :: Flying Through the Vortex (http://www.aviationtoday.com/rw/personal-corporate/personal-ac/Flying-Through-the-Vortex_85872.html)

[Bellrider]

sorry for that question! I´am a littlle confused!
Hovering HOGE with max power available, heli starts decending due to not enough power availible. In that case i can´t increase power or left pedel (still full forward).
Settling with power and Vortex are quite close togehter. But can´t get out of settling with power with that method..

[Thomas coupling]

The other thing to be very clear about with Tim Tuckers description of VR is that it isn't Vortex Ring that he talks of. He should be more circumspect and call it: Incipient vortex ring state (IVRS).

For starters he talks about "commencing this above 1000 feet" Yeah - good advice Tim. Like VR induces 3-4-5000 feet per minute descent.

Secondly - Fully developed VR causes intermittent LOSS of CONTROL of the cyclic and or the collective inputs. Its a game of luck as and when the controls respond inside FDVR. So "applying the Vuchard technique".....how?

Thirdly. The VT is another means of departing the vortices, correct? So too, is the normal response to recovery, except instead of popping out to the 3 or 9 o clock, you bugger off to the 12 o clock.

Vuchard technique....my arse! Vuchard buchard......:ugh:

[jymil]

@Bellrider and TC: you both talk about situations in which the VT is not relevant. If you haven´t got the power to hover, you´ll settle no matter what. And if you´re in a 5000ft/min uncontrollable descent, then it might be too late anyways.

VT is for when you´ll be guaranteed to crash with the standard recovery because you´re too close to the ground. At 100 feet AGL, it does make a huge difference whether you need 30 feet to recover or 150 feet.

[Thomas coupling]

jymil

Here we go again - or rather.....no we don't. I'm not going to waste any more time on VRS, SWP et al.
Suffice to say once and for all, the following:
IVRS is identified by buffeting, vibration and unintended height loss under power.
Atleast several hundred feet will be lost before any half awake pilot will identify they are in IVRS.
Once they initiate recovery using normal or VR technique, atleast 1 or 2 hundred feet will be lost. Overall - no-one here has ever recovered from IVRS in less than 2 or even 300 feet. If you have - you did not enter IVRS.

If you find yourself in FDVRS, then goodbye several thousand feet height loss - minimum, while you battle to regain full response from the cyclic/collective (Yaw not normally affected).

Don't ever convince yourself that any of these aerodynamic phenomena will only lose you 50 - 100 - 150 feet. You're in la la land sunshine.
Bye di bye....................:ugh::ugh::ugh:

[Hughes500]

I have spent a long time trying to work this out
1. How can you get out of VR with a loss of 20 to 30 ft ???? I can assure you having been in Fully developed VR where the ac was pitched up by about 75 degrees falling on its tail with IVSI off the clock ( goes to 3000 ft a minute ). My only recovery after trying cyclic in every direction ( result sweet FA ) Lever fully down ( result FA ) only thing left was full right pedal that then put ac into about 80 degrees nose down regained speed, nearly pulled head of the 300 pulling out of dive with about 200 ft to spare. Please someone tell me how full right cyclic and virtual max power with loads of left pedal do anything when you have 3000 ft plus rate of descent with ac pitched about 75 degrees nose up ??? Let alone come out of it with a loss of 20 to 30 ft. How powerful is your f..ing rotor system that is going to stop a high ROD in just 20 to 30 ft ?????
2. I can perhaps understand getting into incipient vortex ring this technique will work but having tried it no real difference to putting nose forward.
3. It appears to me that a lot on this forum don't really understand the difference between Incipient vortex ring, fully developed vortex ring or come to that running out of power. This goes for the books themselves. Last week put a Hu 300 into " VR" 20 inches of MP 10 kts downwind 700 ft min rate of descent ( according to most books you get VR with 300 to 500 ft min ROD ) pulled lever to max power trying to get into VR and guess what the ac climbed back up, certainly not what the student was expecting !
I am some what concerned that some people who appear to be highly experienced don't have a clue here, what does this say to the younger inexperienced pilot.
I will eat my hat if I am wrong but want to see some actually factual information rather than what appears to be hearsay

[Vertical Freedom]

Crikey Hughes500 ~ couldn't have said it better....thanks :ugh:

==============================================

Pole forward with Power applied; it Works !!! Just Pole Forward !!! ;) It doesn't need fixing, so please get some Airspeed back into Your flight, rather than just a jiggle & dance := recovered in 50' hahahahahahahahahahahaaar :}


Fly always at ETL, or above, whenever conditions permit :confused:

VF

[rotorfossil]

Bearing in mind that the vast majority of VR/settling with power events occur in the latter stages of an approach, the chances of recovery using any technique are unlikely. To reiterate the obvious, avoidance and awareness of the conditions likely to lead to it are the answer.
To add some experience to this discussion, the only time I have got into this situation was from an unrealised downwind approach. The only reason I got away with it (using the stick forward and easing the lever down) was because I had an escape route downhill.
On the above subject, I've noticed over the years that there often is an element of an unrealised downwind approach in the accident reports. I think this is due to the assumption that the wind was so and so at departure and is the same at the destination. Very noticeable at coastal locations where sea breezes can reverse the gradient wind.
Sadly, use of VSI readings as a guide to the likelihood of VR is a bit of a trap due to the large lag in the readings.

[ShyTorque]

I did some very basic maths to try to understand the claim that it's possible to recover from VRS with such a small altitude loss.

3,000 fpm = 34 mph
4,000 fpm = 45 mph

To try to put this in context, I looked up car braking distances. Most sources state these braking distances (dry road surface):

Speed 30 mph = 75 feet.
Speed 40 mph = 118 feet
Speed 50 mph = 175 feet

These are essentially "emergency stop" distances and anyone who drives a car will understand the dynamics of such a manoeuvre. I fail to see how anyone can claim that a helicopter can level off in around one third of those distances from similar vertical speeds.

[Hughes500]

Shy

I had that exact conversation with one of my pilots yesterday, hence my comment on how f..ing powerful is your disc to stop rod in 20 to 30 ft
We really need ETPS at Boscombe to check this out:ugh:

[ShyTorque]

H500, Seems that some don't know the difference between VRS and running out of power!

[[email protected]]

If Mr Vuichard and his acolytes are demonstrating recovery from VRS with less than 1000'/min RoD before recovery then they are nowhere near VRS in the first place.

Nick Lappos posted a chart many years ago highlighting that you have to be descending at approximately 65 % of your downwash speed to even start to get close to incipient VRS - for the full blown event it is 75 to 80%.

The trouble is that people have no idea of their downwash speed and the 500'/min figure comes from the days when disc loading was very low (due to low engine power) and so, therefore, was the downwash speed.

It can be calculated but it is surprisingly high - I know for the Sea King and similar helicopters it is in excess of 2000'/min which happens to be the same as the RoD in autorotation.

If your RoD in auto is a reasonable guide then no modern helo will get into VRS with less than 1000'/min RoD - try stopping that in 50 -75 feet.

Utter bollocks this Vuichard stuff.

[Vertical Freedom]

Hey [email protected] Love Your work :ooh:
If your RoD in auto is a reasonable guide then no modern helo will get into VRS with less than 1000'/min RoD - try stopping that in 50 -75 feet.

Utter bollocks this Vuichard stuff

[jymil]

Any discussion about >3000fpm sink rates and whether you call it incipient VRS or whatever is not really the point. The point is when you come in at e.g. 500 fpm and then you pull collective at 100ft agl just to figure out your descent rate goes the other way. Before you reach a >3000fpm sink rate, you'll have crashed.

Interesting to see how stubbornly some people rebuke this as utter nonsense. If that was the case, they certainly wouldnt teach it at the Robinson safety course. Try it out for yourself, talk is cheap.

[[email protected]]

The point is when you come in at e.g. 500 fpm and then you pull collective at 100ft agl just to figure out your descent rate goes the other way So it is not a VRS recovery at all since you are not in VRS - it is at best a IVRS recovery, in the very earliest stages.

[Hughes500]

jymil
Quite frankly I don't give a diddly squat what they teach at Robinson ( this is the same company that can't even make a set of main rotor blades properly and then come up with a micky mouse solution to repair the **** they put out )
If you care to check some of the posts you will realise that a lot of so called high hour experienced people are talking bolloc.s Tim Tucker included.
Come down and see me I will put a 300 or 500 into what you would call vortex ring < 15 kts, > 500fpm rate of descent pulling power. I will then invite you to recover by simply pulling the collective up. Guess what you will recover, because YOU ARE NOT IN VORTEX RING
Please explain to me if you are in vortex ring, greater than 1000fpm decent how does any rotor system able to halt that within 30 ft. Just engage the grey matter here !

[claudia]

Hughes 500 Refreshing and accurate facts from your goodself.
Exactly why you are so highly regarded as an instructor/ tre.
Also concerned about the knowledge of some of the" experienced"
people on this topic.

[jymil]

It seems possible to get a Super Puma into VRS starting from >500 fpm rod and <30kts according to the accident report from G-WNSP.

Now, back to using your grey matter: recovery #1 requires you to lower the collective, push nose forward and then raise collective again. Recovery #2 requires you to bank into the upstream of the vortex and not lower the collective, but raise it directly. Which one of the two do you think would lead to less altitude loss ?

[jellycopter]

In fully developed VRS, #1 will lose less height. Raising collective will 'deepen' the VRS.

Having lost 6500ft in an out of control Puma due to VRS, I can tell you categorically that in my experience, the Vuichard technique is bollocks. My VRS was so well developed that the cyclic had no effect on aircraft attitude, even at full deflection. I'm convinced that the only reason we got any speed at all to fly out of the situation was due to the very high RoD resulting in an upward force on the horizontal stabiliser thus pitching the aircraft nose down. The cyclic did bugger all, despite trying to force it through the instrument panel! Lateral cyclic would have been cock all use.

JJ

[jymil]

If you are in a fully developed VRS out of control: how exactly is the standard recovery technique helping there?
Both recovery methods are only applicable when you still have some control over your aircraft. You should do something about it as soon as you detect that things don't go the way you want.

[n5296s]

I'm just a novice in all this, but I did start the thread so... if Vuichard only works for IVRS, just how exactly does it differ from the conventional recovery? (a) You go sideways instead of forwards (b) you pull collective straightaway instead of drop-wait-pull.

(a)... so what? The rotor doesn't know or care about sideways, forwards or backwards. I guess maybe the tail rotor thrust potentially makes the translation happen a bit faster.

(b)... as long as you get out of the downwash rapidos and you were only ever in IVRS, dropping the collective probably doesn't make much difference. In fact my original instructor said something like "do it for the checkride but in truth there's no point because by the time you've dropped it you've recovered anyway" (which was ironic because he was also my examiner, but that's another story).

So the advantage, if any, of Vuichard is (a) you may get out of the downwash a tiny bit faster thanks to help from the TR and (b) you don't have the brief loss of lift due to dropping the collective.

If the difference between flying away and disaster is 20 feet, then I guess these may help. For FDVRS it's academic, but then what were you doing there anyway?

[[email protected]]

Going back to your original post - you were referring to SWP which, as we have discussed at length, is not IVRS or VRS.

So, consider your circumstances - you were trying to hover OGE with clearly limited power available (up at the red line you said) so how does the Vuichard technique get you out of that?

The amount of collective you have available is minimal (red line) and applying full power pedal just saps more power. All sideslipping to the right achieves is getting translational lift to the MR which you could get by just moving the cyclic forward instead.

Then, when the vertical component of your Total Rotor Thrust is the only thing opposing your weight, you tilt it, thus reducing the vertical component even further.

I'm really not sure how this is supposed to help!

All the stuff about reaching the upwind side of the vortex is more bollocks because you aren't in VRS, you have just run out of power.


The BIG problem is that many less experienced pilots reading this forum will think there is a magic bullet recovery for IVRS or VRS when the only guaranteed way is to avoid it altogether.

If you want a proper top tip then only approach a hover OGE level rather than descending to it - when you are limited on power it is much easier to assess your real power demand as you approach the hover as you are not trying to arrest RoD and forward speed. As you start to reach your power limit then ease the cyclic forward and fly away if you have any concerns.

[Hughes500]

Jymil

To get out of fully developed VR I think it is luck only, in my case it certainly was or perhaps desperation by using the tail rotor as there was no other option left.
All I can say is never never get into the situation in the first place ! This should be the real mantra of this thread. Now if The Vulchard technique gets you out of incipient state then great, but you shouldn't have really got thee in the first place.

[Rotorbee]

Let's recap for a moment.
Until now we have found out, that the Vuichard technique isn't new. He has rediscovered it.
I searched for a paper he might have written, no luck. Which makes me wonder why, since there is a claim, that the Swiss FOCA was involved. Who knows, the experts there might not be as impressed as Vuichard himself, but keep quite.
Vuichard isn't a test pilot and afaik, the Swiss FOCA does not employ one.
Neither is Tim Tucker.
To my astonishment, it suddenly became a hot topic and quite a few pilots describe it as the new thing to save lives. When you read the comments on the R&W website, one gets the impression Tim Tucker saved the universe single handedly. They almost worship him.
Helicopters crash more often due to SWP (that darn sudden power loss :E pilots often report afterwards) than due to VRS.
If SWP develops into VRS you are out of luck with that technique. You already use take of power and now you want to go sideways demanding even more power from the already sweating engine.
Somehow it does not add up.
Personally I have done IVRS many times during initial and recurrent training and as a CFI (not as many as some of you, I am sure). It is sometimes pretty hard to get an R22 to drop out of the sky. The worst I ever saw had was about 2000 fpm (with a lot of air below me, not only 1000ft). That isn't a fully developed one.
Getting out of it was merely a matter of shoving the stick forward (yes, I have lowered the collective to keep examiners happy, but sometimes one just tries to do something slightly different) and that isn't new either, because some papers suggest exactly that to minimise altitude loss.
Thinking back, I might even have kept the stick very much to the aft, for keeping it in the IVRS. It might be possible, that without changing the position of the cyclic the R22 would fly it self out of it... probably and getting back in shortly after. This might be due to the horizontal stabiliser being behind the rotor disk.
Just once I had a real situation which I realised as a very, very early stage of IVRS. While approaching Palmer AK I got this feeling were all the controls become sluggish and the airframe shudders. A bit more speed down to the runway solved that. Interestingly the windsock on the left showed a head wind, the one on the right tailwind, which I saw later. But that is Palmer for you, where a headwind is a somewhat surprising occurrence that makes you uneasy.

While googeling for more information I found THIS (https://books.google.ch/books?id=AovdKRWSqJAC&pg=SA2-PA38&lpg=SA2-PA38&dq=downwash+speed+r22&source=bl&ots=XoRAnvVxlZ&sig=oO6-vW-npYZU4kaqg-cYO1MUnP8&hl=de&sa=X&ved=0ahUKEwiGleyehaHJAhVEuBQKHZTAAroQ6AEIHjAA#v=onepage&q=downwash%20speed%20r22&f=false).
Reading that, it seems the author is pretty sure you can get into VRS with 300 fpm and overpitching (SWP) while experiments and the 206 chart suggest more like 800 fpm. Which makes me thinking, has anyone ever tried all the techniques in a controlled environment? I doubt that. Looking at an altimeter and VSI with all their lag and installation error does not prove a lot. I could even imagine a temporary effect on the instruments depending if you side-slip or not and with all the downwash hitting the fuselage, the standard instruments might not be very reliable.
The Vuichard technique might just be a variant of another standard technique I read about. In the early stage, just use a lot more power to fly out of it ... if you have. Nick Lappos suggested that the S 64 had so much power it would go upwards in no time at all. A B3 might do the same.
I personally think that the Vuichard technique isn't any better in getting out of it in a very early stage, when the ship just starts to shudder and the controls are all mushy, because when you shove the stick forward not to aggressively you don't loose a lot of altitude if any. In that moment the terrible plunge to hell hasn't even started. Waiting to let the VRS develop a bit more isn't real life. When the whole ship shudders and acts like a rodeo horse and the cows get bigger, even the most daft pilot must realise, that something went wrong a lot earlier. Or shouldn't he?
Having said that, I am immediately proven wrong. REGA had an accident lately, where VRS seems to be the culprit (rumour). The 109 K2 hit the ground pretty hard, tore off the undercarriage and landed on its belly, but stayed upright. It seems it was a tailwind approach that went wrong (stand corrected here, the accident report isn't out yet). Now imagine the pilot would have initiated a side-slip in that situation and hit the ground sideways? Not a nice picture. Depending on the weather and other factors, one will not realise what is going on and one might get quite far into IVRS without clear clues and the moment he does, it might even be too late for the Vuichard technique, if it helps at all. To suggest that the whole point is not getting into it, is correct, but not the reality. You only have to look at the wrong windsock once.
I don't know what the pilot did wrong, but I think he did one thing right. He flew his ship into the crash and it stayed upright. With the Vuichard technique he would have a much harder time to keep the ship upright. Flying sideways at high speeds descending to the ground isn't something I would like to do.

Since nobody ever tried to measure the different techniques and write down the results, we are all discussing something that is merely an idea with some indications from standard instruments without taking into account any aerodynamic and other effects on the helicopter or the pilot. To prove anything, I'd like to see some more evidence, please.
The standard technique is easy, works and does not need more power, while the Vuichard technique is more difficult to master and needs more power, which one probably does not have.
Let's look at another scenario. Imagine you are flying a load on the hook and during the approach you get into IVRS. Pickling the load would solve the problem immediately. Lots of power left but an unhappy customer. Using the Vuichard technique would let the load swing suddenly all over the place. Endangering people on the ground who thought, standing not in the flight path of the helicopter would be save. The pilot not only has to catch the descend, but also the swing of the load. Shoving the stick forward and going around using the predefined escape route more or less straight ahead (I know, it isn't always that simple) seems a lot easier to control. Even if he has to let go of the load, its impact point would be a lot more predictable.

Frankly, I wouldn't say that the Vuichard technique is bollocks, but neither new nor the best way to save my day. As a last resort it might be just the thing.

[jymil]

The accident report on the Rega crash is not yet out but since this is a rumor network: some people think this accident was exactly preventable with VT and the pilot should have been fired.

[Rotorbee]

No wonder. VT was in probably every Swiss magazine. Since it is a Swiss technique, it must be better than anything else ever invented elsewhere. When it comes from Switzerland, it is from a higher authority. Therefore a Swiss pilot must use it if appropriate or not, or else ...

When you look at the following picture, there are a few clues, that he did a good job.
http://www.snoop.ch/img/5117761424968557.jpg

He landed on the grass and the wheels just broke of. The landing must have been pretty hard, but not hard enough to bend the blades to touch the tail boom. If at all it was IVRS at a very early stage with a pretty low sink rate or he had just not managed to get out of it with a lot of power. Not a lot of forward speed either, because the wheels are still there and no sliding marks. An almost perfect hard landing.
Another picture. The windsock in the back shows a wind which is perpendicular to the helicopter. If the wind did not turn until that picture was taken, that would be a side wind.
http://f.blick.ch/img/incoming/origs3523112/0025564895-w644-h429/631494478.jpg

He PROBABLY came in fast (knows the corner, did that every time, not the stable approach with a slow deceleration one does to an unfamiliar place) and during the "breaking" with the nose high, things got ugly. That would be at or below hundred feet (assuming, no facts except experience). He probably even was in a turn toward the pad which is in the background.
In that moment trying to do a side-slip would be suicidal, especially using the power pedal. Adding power, yes, levelling the ship, yes, flying uncoordinated, God no. He wouldn't even had time to use VT, because he would have to level the ship first and then try to fly out of it. For that it was definitely too late.

He might have f***ed up the landing but it looks to me, that's a pilot who knows how to save his ass.

[n5296s]

Injecting life into this old thread (which I started way back)... I flew the R44 with a different instructor today, and he asked "have you ever tried flying out of SWP with lateral cyclic?" Funny really since I think it was a discussion between me and one of their now-departed instructors that got the school interested in the idea.

He said that they'd tried it and got an altitude loss of 100 feet to recover instead of 400 feet with the usual technique. We went out and flew a couple and it certainly worked. Of course this was not from fully-developed SWP, just wait for the descent to start then wait a couple of seconds.

The technique we used was right cyclic, left pedal, pull to 23" of power (max continuous).

[[email protected]]

So what height, speed and rate of descent did you start this from?

Did you try it with left cyclic and right pedal (which would have given you more power available)?

[FICH]

Claude Vuichard is a former transport pilot which has flown thousands of sling operations in the swiss alps. In sling ops your are always very close to the VRS, since you have a lot of descends with 0 or nearly 0 forward speed.
If you are 100 feet or so above ground and a vrs develops, you have no chance to escape with the "collective down and gain airspeed" method, since you will crash straight forward in to ground.
But not only in sling business, also in school- and all other flights, in which flight phase is the greatest danger of vrs? Exactly, in the approach segment when you are very close to the ground. With the old method, the only influence you have, is the influence about the size of the debris field on the crash site.

With the vuichard recovery technique you have a real chance to escape from the vrs, but you have to know the signs to identify it early enough.
If i read posts from peoples who lost 5000ft, i'm wondering what they did in the meantime?!

With the mentioned R44 you have to apply right cyclic and left pedal, since you need to pull max power and keep the nose straight fwd with a lot of left pedal to create the needed TR-thrust.

If you would try to escape to the left, you will need to lower the collective to apply max right pedal. But in this case you will loose much more height!

[[email protected]]

With the vuichard recovery technique you have a real chance to escape from the vrs, but you have to know the signs to identify it early enough.
If i read posts from peoples who lost 5000ft, i'm wondering what they did in the meantime?! this is because you are talking about recovery from IVRS using the Vuichard technique - this is not the same as trying to recover from full VRS.

If you would try to escape to the left, you will need to lower the collective to apply max right pedal Why??? If you apply full left pedal and sideslip to the right, you are taking power to provide anti-torque that could be available to the main rotor to oppose your rate of descent. If you apply right pedal and sideslip to the left, all the power is available to the main rotor. In both cases, if you try to pull too much power, you droop the Nr and begin to settle with power, just making things worse.

The sideslip in either case is a very small part - the main element of recovery being the addition of maximum power - this will counter your RoD only in the early or incipient stages of VRS - if you are in full VRS it will just make things worse.

If a proper empirical test was conducted, it is my guess that the best technique for recovery from IVRS is to put the nose forward slightly and pull max power rather than messing around with sideslip. Unless you are going vertically down - normally on approach you will have some forward speed - the quickest way to get airflow over the disc is to move forward faster.

[Rotorbee]

Almost 50 years ago I flew with an ETPS (Empire Test Pilot School) graduate in a RN Wasp. He demonstrated fully developed VRS - and I do mean it was really fully developed - we started at 9000ft, commenced the recovery at about 8000ft and recovered at just above 4000ft with the ROD having been pegged to the bottom of the dial. No way can you recover from fully developed VRS within 50 ft!!!!

They did recover from a FULLY developed VRS, which is quite different from a incipient VRS. I personally have never been there and don't want to go there, neither sit in that helicopter but let's give the man - a test pilot - credit for knowing what he was doing, since he started at 9000ft.

And as you can see in post #4 the technique isn't even new. Your hero just gave it a name. One wonders, why it did not become the standard technique.

And again from the old timers:
On learning to fly over 50 years ago, we were taught to do VRS recoveries. When the rate of decent was around 4000 to 6000 ft/min we would initiate recovery by lowering collective & pushing stick forward. When the air speed came alive we would pull the stick back & apply power to initiate a climb.

The point was made very strongly that the tail rotor hadn't stalled, only the main rotor, so if the cyclic was too sloppy & wouldn't nose down, we would put in a boot of pedal as all you wanted was airspeed & it didn't matter in which direction you were going. Worked every time!

I just have a problem with the stalled rotor here. Does it stall in a VRS? I miss something in that picture. Anyway, since building up 5000ft/min ROD takes a while or even 2000ft/min, probably longer than the rope that is still dangling from the belly, the whole discussion is moot since either way HTG will have happened by now in the above described low level situation. The whole thing is about incipient VRS (the real world. If you can develop 2000ft/min ROD in a vertical descend without hitting the ground you are certainly trying to fly down a mine shaft).
Here we have a problem. It would take quite an effort to prove any advantage, since even a slight variation of wind speed, weight or sensitivity of the pilot could tip the balance in one or the other direction. I personally have flown out of an incipient VRS with almost now height loss, just because I caught it in the first moment of sluggishness of the controls. Easy when you know that it is coming. A centimetre of forward stick and you'r out of it. No "lowering collectiv". That's modern helicopters for you. They do not tend to suddenly fall out of the sky with no warning. That is probably the reason, why much more helicopters are bent by SWP (that terrible sudden power loss) than with VRS.
By now we have made a mountain out of a molehill. VRS accidents happen but one has yet to prove that the recovery procedure is the key to prevent them. My completely unproven feeling is, that the recognition of the situation is the problem. "Early enough" as FICH stated. And I go with crab. In an incipient VRS during an approach, stick forward and pull power is the easiest way to save the day. If you want to put in some pedal, be my guest.
Both methods work apparently but this rediscovered technique is harder to learn.
Just a thought, if one is slinging stuff slow and heavy and gets into incipient VRS, pickling the load should solve the problem in a heart beat. Customer might not like you afterwards.

[FICH]

The sideslip in either case is a very small part - the main element of recovery being the addition of maximum power - this will counter your RoD only in the early or incipient stages of VRS - if you are in full VRS it will just make things worse.

No sir. The main element of the VT IS the sideslip, produced due to the bank and the tailrotor thrust. As soon as the blades reach the upwind part of the vortex, the recovery is completed.

http://enjoyflying.net/wp-content/uploads/2015/09/2.jpg

[[email protected]]

No sir. The main element of the VT IS the sideslip, produced due to the bank and the tailrotor thrust. As soon as the blades reach the upwind part of the vortex, the recovery is completed. Now take your diagram and turn the helicopter through 90 degrees - tilting the disc forward gets the blades to the edge of the vortex just as quickly (if not quicker as you already have some forward speed).

The main element is pulling max power - that is what will reduce your rate of descent - the more you tilt the disc and the more you sideslip, the more you tilt your thrust vector away from the vertical which is where it will have most effect on your RoD.

[Lonewolf_50]

No sir. The main element of the VT IS the sideslip, produced due to the bank and the tailrotor thrust. As soon as the blades reach the upwind part of the vortex, the recovery is completed.

http://enjoyflying.net/wp-content/uploads/2015/09/2.jpg
What forward and lateral speed are you presuming in the use of this model? If there is forward momentum it needs to be overcome, which takes time. Is this model for forward speed less than 10 knots? Lateral speed 0 knots, or negligible?

[Rotorbee]

Well, I would not take this picture as the real deal. It is a bit more complicated.

Shawn's book (https://books.google.ch/books?id=VYAGAgAAQBAJ&pg=PA203&dq=vortex+ring+state&hl=de&sa=X&redir_esc=y#v=onepage&q=vortex%20ring%20state&f=false) has a more complete picture.
The airflow is in fact highly chaotic - hence the low frequency vibration or waggling of the ship all over the place - and slipping the ship through the vortex on the right ... I doubt that this is the case. I suspect that the vortex disappears before it engulfs the stalled area, since the rotor is now flying through clean air and normal airflow is restored. To have a vortex, one needs a tip of a blade and the point around which the vortex turns is normally beyond the tip, because otherwise the blade would not be able to feed any energy into it.

Others have discussed that, too. (http://helicopterforum.verticalreference.com/topic/19370-the-vuichard-recovery-flying-through-the-vortex/)

What strikes me here, is the fact, that Tim Tucker would let develop a full VRS, which is not real world and again it is stated, the technique isn't new. For tandem rotor ships it is even the standard technique. SASless should know more about that.

Let's keep that in mind:
Another area of concern, pilots sometimes have difficulty recognizing the difference between VRS and settling with power, much less which technique to use under each of those circumstances. Forward cyclic and reduce collective works for both. For the so-called Vuichard Recovery that may not be the case, further analysis is needed.
It is hard to argue with this. One should keep in mind, that with all these techniques, there is always a week link, and that is the pilot who has to apply the right one in the right circumstances. Adding complexity to the job will not save more bent metal. If the pilot just needs one more second to figure out if it is IVRS or SWP, the whole advantage (if there is one) of the now know as Vuichard Recovery technique is gone.

Frankly, in a non scientific approach that is used in this case, it is becoming more of a dogmatic discussion (who has the biggest).

An interesting read from the antediluvian times.
http://naca.central.cranfield.ac.uk/reports/arc/rm/3117.pdf
Adding power was the technique then. Or wait until the nose drops. Scary.

[FICH]

If there is forward momentum it needs to be overcome, which takes time.

Even if there is a forward momentum, you'll still be able to apply right bank, add max power and left pedal.

With the forward escape, you have only the vector from the main rotor. With the sideway escape, you have additionally the tail rotor thrust.
Therefore your escape out of the VRS is faster, and faster means less height loss.

And am talking about a real vortex, in which a solely increase in power only will increase the ROD...

[FICH]

Whether it was a swiss, an american or an african pilot who has developed this technique... I don't care about that.

Fact is, it has a lot of advantages over the nose & collective down method, since you will not be able to do that maneuver in the final approach segment, where the probability of a VRS is the highest.
Why should we teach and learn a method, which will destroy the helicopter?

If the "other" VRS recovery is effectively controlled and reflexively like the introduction of an autorotation, we will be able to prevent a lot of this sad accidents.

[Freewheel]

Whichever technique you feel is superior, or available to you in a specific circumstance, one thing remains true;

Understanding that you are entering circumstances which may produce IVRS/SWP/VRS and having a plan to avoid or recover from any of those phenomena is going to produce a massively superior result to blundering along with any technique rattling around the back of your brain waiting to be found, assessed and acted upon.

It seems clear that the technique Mr Vuichard and Mr Tucker have taken the time to write about is a valid one, which can be added to the tools available to pilots open minded enough to understand it's application to their circumstances.

The rest is mental (and keyboard) masturbation.


Carry on......

[[email protected]]

The initial claims for Vuichard technique were for recovery from fully developed VRS and stated recovery in tens of feet - then it was touted as recovery from IVRS, please make your minds up.

In fully developed VRS you have little control of the main or tail rotor due to the random variations in thrust available at various positions across the disc so trying to utilise sideslip with maximum power applied isn't going to help and will probably deepen the condition.

If we are talking about IVRS - which I think is valid - then application of power is likely to help re-establish the downward flow of air through the rotor without stalling the inboard section (as the RoD isn't high enough).

The sideslip may help or hinder the recovery because you don't know where the worst part of the downwash is - the assumption is that it is ahead and below but that may not be so in a crosswind situation.

Sorry if you think it is keyboard masturbation Freewheel but some of us think that is the height of idiocy to recommend a technique which the inexperienced might view as a 'magic bullet' for VRS recovery - if they believe the technique is so effective they may well not treat the low speed, high RoD environment with as much respect or caution as they should and subsequently get themselves into big trouble.

Pilots must also understand that SWP is not the same as VRS and using the Vuichard technique in this case will make things much worse.

[Vertical Freedom]

a big dose of 'pole-the F-forward', leave the power on, or apply more to top of yellow & maintain some heading :O ~ works a treat; every-time :8

Let us all focus our hopes, our dreams, our desires & aspirations to maintaining our airspeed, (translational) for, the loss of which can cause a whole plethora of misgivings :{

The Vulcan technique does not return airspeed :(

Happy Happy :ok:

VF :)

[FICH]

I fully agree with you, that the target number one is to avoid the vrs.
A student has to learn the causes and the initial signs before **** gets real.
But he has also to learn to handle the real ****...

Concerning IVRS or VRS, can you tell me according your judgement where the transition between these two things is?

For example, i fly the helicopter into vrs. Random yaw, vibrations etc. I don't do anything. Sinkrate begins to increase. I don't do anything. At 1000ft/min, i apply power. Sinkrate increases more. Is that IVRS or full developed VRS?
Only that we speak about the same...

[[email protected]]

FICH that is full VRS and that will take a lot of height to recover from.

As you say it is best recognised and avoided:ok:

[Thomas coupling]

http://www.pprune.org/rotorheads/332636-do-uk-military-teach-vortex-ring.html

http://www.pprune.org/rotorheads/416274-teaching-vrs.html

http://www.pprune.org/rotorheads/279755-vortex-ring-alt-vsi.html


Fill your boots - oh newcomers.

[FICH]

FICH that is full VRS and that will take a lot of height to recover from.

And in this full developed VRS we practice the recovery with our students and pilots. And it needs very little height!
Have you ever tried it?

I will try film it for you, next time i do that with a student!

Cheers

[Thomas coupling]

Oh dear.........................................

[Dynamic Roller]

Tim Tucker writes (http://www.aviationtoday.com/rw/personal-corporate/personal-ac/Flying-Through-the-Vortex_85872.html#.VsT31lUrJhE) that as he teaches or demonstrates the Vuichard technique, "I frequently allow a high descent rate to build prior to initiating the recovery to clearly show how efficient this new technique really is."
So that's clearly not IVRS. Maybe can only be done in a Robbie? :)

[FH1100 Pilot]

With regard to the VT, let's remember one or two things.

First, for SWP/VRS to occur the helicopter will most assuredly be below ETL. So its ground-track (if any) will be slow. Let's assume it's traveling forward slightly and not coming straight down when the pilot experiences the dreaded IVRS.

Pushing the cyclic to the right while simultaneously pushing the left pedal will *not* result in the helicopter sliding perpendicular to the ground track. No, the helicopter will yaw to the left and the helicopter will probably continue along the previous ground track or approximately so. The combination of right cyclic and left pedal would then have the same effect as lowering the nose, but with the added benefit of thrust from the tail rotor.

I've thought and thought and thought about the Vuichard Technique, trying to come up with something meaningful to say one way or the other. I mean, I've been flying these things for a long, long time so you'd think I'd have learned something by now.

Initially I was predisposed to reject the VT out of hand. However it appears that I've learned something new.

[FICH]

No, the helicopter will yaw to the left and the helicopter will probably continue along the previous ground track or approximately so.

Nope, since you are pulling max power and keep the nose with the (left) pedal on your present heading, the helicopter will not yaw.
You must not allow the helicopter to yaw!

[Thomas coupling]

FH1100: I think you've got traction there, but only just.

What I think you are saying is that DURING IVRS, the VT has merit. If this is correct, I happen to agree with you.

Where I think the problems lie, are as follows:

1. People who describe the VT as a panacea to fully developed VRS, clearly do not understand the situation they are describing.
2. A lot of people do not understand the difference between IVRS and FDVRS.
3. During FDVRS, the cyclic will not do what you ask of it.
4. Ab initio's and clearly low timers (possibly others) have never been shown IVRS or how to recover, other than by word of mouth or in a book.


PS: Be careful mentioning SWP! A different ball park and almost certainly too late to employ the VT, I would suggest!

[Rotorbee]

Since we are so nicely going around in circles and FICH is rather frustrated with us not getting it.

The one for the R22
http://i118.photobucket.com/albums/o95/ichris7/R22%20VRS%20Chart_zpsxdocagiu.jpg

Just for arguments sake, can we agree on the area with light turbulence and thrust variation as IVRS, and the dark area is FDVRS?
In that case: I believe that no many of us have ever experienced FDVRS. All we talk about is IVRS. Charts for other helicopters are similar.

If you go straight down, you are in IVRS, not FDVRS, when you descend with 40 degrees, neither. And after a while you drop out of VRS at the bottom.

Now what are we talking about? Is it really that important, to get out of VRS or IVRS as fast as possible. The goal one has as an instructor is to teach students to use superior skill in judgement, so that they don't have to use superior piloting skill.
Let's assume the Vulcan Technique works as advertised. Great! Cool! How much better? Somebody should find out with calibrated instruments and a series of VRS test flights. Would be an interesting paper for a aeronautical engineering student.

As soon as the pilot feels the low frequency airframe vibration and the trust variation, he/she should take action. The these indications must not necessarily come from VRS. It might be just the loss of ETL and some SWP. In which case VT would not save the day.
A down draft in the lee of a mountain isn't VRS, but it might feel quite similar.

To show different techniques to students is a great thing and letting develop a high sink rate and getting out of it, is something every student should know, but I believe that this is more a demonstration of the awkward aerodynamics of the helicopter than something useful in everyday life.
"All those terrible accidents" that FICH stated, do not happen. They are rather few and far between. VRS accidents are not on "most wanted" list of aviation authorities in the world. That's probably just because the training works pretty well to avoid the shaded area in the first place. When you have to use the Vulcan Technique to get you out of a desperate situation, you have already pretty much ****** it up before.
One thing might speak in favour of the Vulcan Technique. The two accident reports I found which suspect VRS stated that the pilot tried to arrest the sink rate by adding power; the natural reaction but makes it worse. A bit of uncoordinated flight or only stick forward might have saved the day here. Apparently the pilots didn't realise that they were in VRS.
The conclusion would be: show the students the Vulcan, but hammer it into their brain, to avoid VRS and if they get low frequency vibration and thrust variations, don't try to salvage an approach by just adding power and flying uncoordinated. Start again. Go around. Speed up. It might have been something else than VRS. It is easy to identify something when you want it to happen. It is much harder, if it surprises you.
It is an additional tool for the (advanced) pilot, but it is not the ultimate thing one would use in panic mode and it isn't universal. In a French of Russian helicopter you must reverse the movements. That just does not work for a standard emergency technique. Keep it stupid and simple.

[ShyTorque]

As I've written before, the maths don't justify the claims.

VRS can result in descent rates of 3,000 ft per minute or considerably more. Been there, seen it in a military Puma. VSI only went down as far as 2,500 fpm and it was firmly pegged on the bottom stop.

3,000 feet/min ROD = 34 mph downwards.

Some here claim that this can be stopped in less than 50 feet?

The claim is that aerodynamic control during the recovery from fully developed VRS is more effective and more sudden than an emergency stop in a car on a dry road! Try driving any non-ABS equipped car at 34 mph, applying maximum braking and see how long the skid marks are.

[Rotorbee]

Oh no, 20 to 30 feet.
But let's assume they had 1500ft/min ROD which is more realistic in the R22 and that would be just 17mph.
That is a mere 3.17m/s^2
Possible. It is a third of one g. Around 19deg of bank? Not something that folds the blades.
But that is with instruments that lag and the human eye. It would be interesting to use one of flight recorders for sail planes to get a more accurate reading.
With your numbers it would be 7.62m/s^2 and it would take about two seconds, until the descend stops. Not unheard of.

[Thomas coupling]

Don't mention the Vulcan's.

What did the Vulcan's do for us? :{:{:{:{:{:{:{:{

[ShyTorque]

.....let's assume they had 1500ft/min ROD which is more realistic in the R22Doesn't sound like fully developed VRS to me, not in any helicopter.

[Rotorbee]

Which is exactly my point and is shown by the diagram above. It looks similar for the JetRanger.
Ray Prouty writes:
“In a wind tunnel or long track test, the instability can be documented because the model can’t go anywhere. In flight, however, the instability prevents the pilot from finding a steady flight condition in which to take data. The flight test points in the literature that are identified as being taken in the vortex ring state were undoubtedly obtained under highly transient conditions.”
and
“Staying in the vortex ring for any length of time isn’t easy. It depends upon maintaining a nearly vertical flight path. There is some evidence, however, that a “glide” slope of about 70° is worse than a true 90° descent.”
Which again is confirmed in the diagram.
I do not know the down wash velocity of the Puma, but it is possible that at 3000ft/min the ship is already in the powered autorotative state. Which must feel quite similar to IVRS, since a portion of the downwash is still pushing against the upflow and therefore inducing vibrations, but the vortex around the blade is gone.

And from Dr. J. Gordon Leishman. “Principles of Helicopter Aerodynamics, 2nd Edition – Helicopter Performance”
· While operation in the VRS is obviously undesirable, it can be entered inadvertently through poor piloting technique. Recovery is usually attained quickly, however, by the application of cyclic control inputs to cause some increase in forward or sideward airspeed to sweep the recirculating wake away from the rotor disk.

I think we are all guilty of a misconception. FDVRS in helicopter aerodynamics is NOT defined by THE HIGHEST SINK RATE but by the worst turbulence and thrust variation (and the existence of the vortex obviously).

@TC: The Vulcans have given us Pok Tar.

[[email protected]]

For example, i fly the helicopter into vrs. Random yaw, vibrations etc. I don't do anything. Sinkrate begins to increase. I don't do anything. At 1000ft/min, i apply power. Sinkrate increases more. Is that IVRS or full developed VRS?
Only that we speak about the same.. FICH - this is what you posted and it mentions raising the lever increases the RoD - and then you posted this And in this full developed VRS we practice the recovery with our students and pilots. And it needs very little height!
Have you ever tried it?
So are you raising the lever to deepen the VRS before you recover or are you in fact taking the recovery action before you deepen the VRS?

[Rotorbee]

Found a neat little video about the Cabri in VRS:

Yv-cxQnEcNg

Note how long it takes to get the ship sinking and then it peeks at about 1000ft/min ROD. That's a gentle little beast.

[Thomas coupling]

Thats not VRS, its IVRS your vertical rate of descent didn't go past 900'/min :ugh:

FDVRS would indicate sustained sink rates in excess of 2-3000'/min

[Rotorbee]

TC, I know you are pretty good at what you do, but give Prouty and other aerodynamist credit for their work.
If Vd/vi (thats decent velocity over induced velocity) is above 1.5, they at least consider the vortex gone for good. That's about 2000ft/min in anything I know.
If I say VRS, I mean both, IVRS and FDVRS.
I at least learned something about it during the course of this discussion.
a. Normal recovery or DT is frankly a moot discussion. If I get into really bad shacking and waggling I have messed it up so profoundly in the beginning, that 30 or 50 feet do not make a big difference.
b. From reading a few things, dusting of Prouty's books, and yes, quite a bit googling, I learned that The Beast is elsewhere, not in the descend rate.

“Much of our knowledge of this state comes from flight and wind tunnel tests. Based on this experience, we know that unsteadiness starts at about one-quarter, peaks at three-quarters, and disappears at 1¼ times the hover induced velocity.”

Raymond W. Prouty. “Helicopter Aerodynamics – Vertical Climbs and Descents”


And if Dr. Gordon Leishman's book wasn't so expensive, It would be on the way to my desk by now (if anybody has a copy he does not need anymore? And there is an article about VRS in the AHS Journal, could somebody scan that for me, please with a cherry on top?). But now I know, I can much safer descend straight down, than in a 40° angle and suddenly the Super Puma accident makes sense and a lot more does, too. It think, I am at least on the right track to understand VRS a bit better. I was taught in beginning things that are not true. I truly believed in gyroscopic precession (and I looked at a rotor head and the angle wasn't 90°. That's were I started to get suspicious), in the centrifugal force, density altitude affects turbine engines. You can count down almost all the myths Nick brought up in that famous thread, I would probably been a believer at one time in my life.
If anybody wants to believe the FDVRS with high sink rate, be my guest. You can try to explain to me the VRS diagram above with the high sink rate, I am all game and I will not interrupt and I will admit that I am wrong and I can't read the diagram correctly, but in that case, you might contradict a few giants in helicopter aerodynamics, behind which I hide.

[Paul Cantrell]

.....let's assume they had 1500ft/min ROD which is more realistic in the R22

Doesn't sound like fully developed VRS to me, not in any helicopter.

I agree with ShyTorque. The first time I went to the Robinson safety class in the 80's the instructor (Hi Rod!) demonstrated it to me. Not only was there no shaking or vibration (he just really nailed the middle of the vortex I guess), but the VSI quickly pegged at 2,500 ft/min. Then a little forward cyclic and we flew out of it pulling I guess a couple G's.

A lot of people will have a sink rate of 500-1,000 ft/min and some vibration and say they're in FDVRS, but I think they just have enough of the disc sticking out into the airstream that they're getting some net lift to keep the sink rate low. It's *hard* to find the center of the downwash and stay in it (unless it's snowing!).

In that R22 demonstration the transition from OGE hover to falling out of the sky gave little warning: I usually describe it to my students that it was like "stepping off a roof". Lots of fun, when you're at a few thousand feet!

[n5296s]

So what height, speed and rate of descent did you start this from?

Did you try it with left cyclic and right pedal (which would have given you more power available)?

(Wow, that happened quickly. Only just saw this).

Honestly this wasn't fully developed VRS. I was with a fairly inexperienced instructor, who'd just been shown this himself. To get anywhere close to the "real thing" I'd want to be with someone who has been there themselves, preferably several times.

We were at 1000 feet and let things develop for maybe one second before starting the recovery, so still very much incipient. We only did it with right cyclic / left pedal.

I'm sure it would be lots of fun to be a helicopter test pilot - but I'm not one!

[[email protected]]

Rotorbee - I believe the diagram simply refers to rates of airflow up through the disc all the way from hover to autorotation but does not cover the aggravating and deepening of the stalled section and the enlivened tip vortices caused by raising the lever in the middle of the IVRS and turning it into FDVRS.

[[email protected]]

Rotorbee - the reason that the diagram has a dotted line marked autorotative state and windmill brake state is that in a vertical descent (in auto) the rotor is slowing down the air passing through it and extracting the energy to keep the rotor turning. As such there is a limit to the RoD in auto because of the size of the rotor disc - although some of the inboard section is causing rotor drag, the outer areas are producing rotor thrust (with the tips creating drag again.

The point is that essentially none of the disc is stalled (apart from the absolute root) and it is all providing a useful function in slowing the RoD.

Now in VRS, when the root end of the blades are stalled due to high AoA (collective raised) and the outboard section is enveloped in a very high drag vortex, only a small part of the disc (a ring between the root and the tips) is producing lift and/or slowing the airflow down.

The more the lever is raised, the worse it gets so the size of your rotor disc (or that part that can slow your RoD) is greatly reduced, leading to much higher rates of descent than can be experienced in auto.

This is why in FDVRS there are the stories of 3 - 5000'/min RoD and why it is so deadly - and why the VT just won't cut it in FDVRS.

[Rotorbee]

Crab, I agree.
But:
With adding power I pump more energy into the vortex, how much does the vi change? Can you achieve a vi of 2000ft/min to keep the rotor in the shaded area? Or is the added power used, just to overcome the added drag of the stalled area?
One can assume, that the vortex will always be there, even at the highest RoD, because otherwise the rotor would completely stall and that would be the end of it. That does not happen as we know. But how big is it and where is it.
A bigger stalled area or a bigger vortex would be hard to tell apart, with all the turbulence produced from the fuselage and stalled area.
I am not absolutely convinced, that at high RoD, where Vd/vi is higher than 1.5 (there is a limit to vi) the vortex is still the problem, because it should by now be blow above the disk, as wind tunnel test show, where it's influence would be greatly diminished, because the following blade would not hit it smack on to pump energy into it, but I would still have all the ingredients of the controls not responding and so on, due to the stalled area. Which would not go away, but would get bigger.
In that case the VT would not work as advertised, it would just add a bit TR-trust to help speed up the ship to get the stalled area flying again, because that is still the whole point, to stop the descend. But since we are talking about a disk, it does not care about left, back or front. I suspect that moving the ship sideways (crab) is just faster with the help of the tail rotor than nosing over.

Instead in the darker area, I have the perfect situation to pump the most energy into the vortex with each blade, because the ship sinks too fast for the vortex to sink away and not fast enough to get the vortex blown above. That's why in that area you get the worst turbulence and control problems (the biggest and meanest vortex). If you move the vortex off the tip inside, it will be blown away pretty fast. How much control I would have left there, is not something I can find out. Reports of flight test show, that it is extremely difficult to stay inside and a very disturbing experience.
As it happens, in an early NACA paper, the dark grey area was a half circle starting at zero forward air speed. Flight and wind tunnel tests have shown, that this isn't the case and now it is between 70° and 40°. That's a problem I still have to get my head around.
Anyway, I still think the VT solves a artificially blown up problem. It is a trick of last resort.

[n5296s]

One thing I should have mentioned: the reason why my (relatively low time) instructor was interested in VT was because he said they'd found quicker recovery - iirc 400 feet to recover with conventional technique, versus less than 100 with VT.

So we went out and flew both. We flew them as identically as we could, and they both recovered in less than 100 feet. Obviously this was from just-barely-I VRS, as I said we waited one second from starting to feel the shaking and see the altimeter start to drop, to recovering.

So the VT works, but from IVRS it doesn't really make much difference, unless you have a cliff face directly in front of you.

[[email protected]]

N5296s - So not really in any form of VRS then, just slow speed with a RoD that you had enough power to overcome.

Rotorbee - the problem with assuming the TR thrust will help is that in FDVRS and to some extent IVRS you will experience random pitch roll AND yaw so you might not have that as an immediate option.

According to Nick Lappos, if you have enough power you can muscle yourself out of VRS - it is just a question of overcoming the massive amounts of rotor drag - not many aircraft have that capability.

I know that those who used to do the VRS demo on the Sea King sometimes struggled to get the aircraft into it (at 10,000') and sometimes it pretty much flew itself out again. I think you have to work hard (or be very unlucky) to keep in the very high RoD area - but it clearly can be done.

[FICH]

Claude Vuichard has just launched his new website, on which his demo video is integrated:

https://vimeo.com/156886502

[Rotorbee]

Oh boy, he is really trying to get himself into the history books.

@N529s: Was to be expected and you point out, why the whole VRS recovery discussion is lame. I think your test has merits, because the best thing is to avoid VSR altogether, the second best is getting out of it as early as possible, the worst is to let build up a huge descend rate and probably crashing before you wake up.

Crab, I could not agree more. I only have my doubts about the common FDVRS definition. Every research, every aerodynamics paper, Prouty, Antonio Fillipone, all of them show, that at the claimed high descent rates, there is no real VRS anymore. While you can't get rid of vortices completely, the rotorblades do not sustain a huge vortex ring, because the air molecules just will not follow a ship down at that speed. Stubborn little bastards.
Therefore Vuichard has an easy game getting out of it. He isn't even in there. All he does is getting rid of the stalled area. The tail rotor is perfectly working in that state. It might even be faster than pushing the stick forward, because there is additional help going sideways from the tail rotor and going sideways will not loose that much altitude compared to shoving the stick forward to the stops and literally diving out of it. In that case I still loose altitude when the VR is long gone. Speeding up the ship from lets say 10 to 15 knots in any direction is done in a blink of the eye and your out of it. If N529s is willing to do another test, he could measure stick displacement. But that is rather difficult. Isn't there an app for this?
(Just an idea. Two pencils, a ruler, two rubber bands and a knee pad. Make an H with the ruler and the pencils. Hold one pencil like Shawn Coyle does it with the new students and place the other pencil on the knee pad - with a paper. Crude but might work).
Will the Vulcan Technique save any lives? I am sure the claims will come, but since nobody is crazy enough to repeat the same mistake willingly just to prove anybody's point, we will never know for sure.
And I go with Nick Lappos again:

Like Typhoid Mary, VRS has been blamed for crimes where it wasn't even in the neighborhood
Surprise, surprise, it was SWP.

[[email protected]]

Strange that the last few 'demonstrations' don't show any of the instruments and are just pretty pictures of the Eiger.

Not even remotely convincing - note that the ones with the instruments don't show anything like the 4000'/min RoD claimed for the last clip after 3 secs in VRS.

Smoke and mirrors and don't try it at home:ok:

[Rotorbee]

4000ft/min after 3 seconds needs about 3/4 of a g (6.8m/s^2). That would be almost free fall of a sky diver. Oh, the doubts.
To get out there in a second you need 20.3m/s^2. That's more than 2g.
And since I am pretty sure that there isn't a upwind part of the vortex - because the vortex isn't there at 4000ft/min, I wonder what really happens there. Oh, and the VSI only goes up to 3000ft/min.

... and whatever he means with full VRS.

[Vertical Freedom]

Watched the Vulcan tech vid.......Bullocks I say, smoke & no sense :ugh: nothing proven - a few easy recoveries at 1,000 fpm rod,, what a crock, he's just swp no vr at all :*

[[email protected]]

And also worth highlighting that the use of 'max power' in a 350 might achieve something but in a R22 (which has just enough excess power to pull the skin off a warm rice pudding) you might just put yourself in SWP using the VT.

[Hughes500]

Just watched the video what a load of rollocks. The N face of the Eiger is 5000 ft ( you can only really see on the video from death bivoac to the white spider and to the summit, less than half the full wall ( looked at climbing it when i was young dumb and full of ... but it looked too terrifying ! )I would love to see how he gets into FVRS so quickly. I have been in FVRS as stated in a previous post and i can assure those who have not been there that the North wall would be going up a dam site quicker than is shown. There is no pitching / rolling massive vibration that I encountered so i seriously doubt that he is in FVRS probably just a high rate of descent that most helicopters can power out of . In the case of a Hu300 800ft a min and she will climb back up, Hu 369 about 1000 ft a min those are all from a high hover dumping the lever and at 800 ft a min pulling power back in !
Oh well i suppose i could be wrong

[ShyTorque]

That looked very much like how I recall my QHI's very lame demo of "vortex ring" in a Whirlwind almost forty years ago, up around 10,000 feet.

"There, vortex ring!" he said, "Did you see that?"

"Er, no".. said I, honestly.

"Well that's all you're seeing", he said. and that was it, end of demo.

Nothing like what FDVRS really looked like when I saw it some years later!

The demos remind me of "stall recovery at the incipient stage" in a fixed wing. Just lower the nose slightly and fly away, easy and rapid recovery because it's not a fully developed stall.

Sorry, not convinced at all by that video but in fairness, just like a fixed wing stall, the incipient stage is the best time to recover (if you can do so).

[Rotorbee]

You guys missed something.

Vuichard Recovery Aviation Safety Foundation (http://vrasf.org/)


And please, donate, it's for a good cause.;)

[[email protected]]

Good grief!!:{

[Thomas coupling]

So that is confirmed then, the man himself confirms by describing and also by videoing that his technique is a way of exiting quite early onset of INCIPIENT VORTEX RING once and for all. he didnt last more than 3 seconds inside IVRS nor did he exceed 900 feet per minute (which is another indication he didnt enter FDVRS).
We all now know where this technique comes from and why it is so damn convincing - don't we?

My question is therefore:

Why in the name of JC is he asking for a donation towards his web site that is describing absolutely NOTHING special whatsoever?

Can you please donate to my project:

Changing direction in a helicopter without using pedals?

FFS what a massive disappointment after all this hype:ugh::ugh::ugh::rolleyes:

[Rotorbee]

When recovering from a settling with power condition,
the pilot tends first to try to stop the descent by increasing
collective pitch. However, this only results in increasing
the stalled area of the rotor, thereby increasing the rate of
descent. Since inboard portions of the blades are stalled,
cyclic control may be limited. Recovery is accomplished
by increasing airspeed, and/or partially lowering collective
pitch. In many helicopters, lateral cyclic combined with
lateral tailrotor thrust will produce the quickest exit from the
hazard assuming that there are no barriers in that direction.
In a fully developed vortex ring state, the only recovery may
be to enter autorotation to break the vortex ring state.
Tandem rotor helicopters should maneuver laterally to
achieve clean air in both rotors at the same time.

faa-h-8083-21 Helicopter Flying Handbook 11-9

And before you get all excited because about the SWP, the definition of VRS/SWP given by the FAA:
VORTEX RING STATE (SETTLING WITH
POWER)
Vortex ring state describes an aerodynamic condition
where a helicopter may be in a vertical descent with up
to maximum power applied, and little or no cyclic
authority. The term “settling with power” comes from
the fact that helicopter keeps settling even though full
engine power is applied.
That's fine with me, since the FAA has to be careful not to puzzle to many old CFI's who have taught SWP for their whole life.

That book is from 2012. Since the FAA isn't the fastest agency in the world, we can assume, that it took them a few years to get to that point.
In the acknowledgements the FAA has the guts not to mention Vuichard for his contribution, neither Robinson nor Tim Tucker. Didn't they know, that Vuichard owns the rights? Or have the authors just known that stuff for years and did not bother. According to the FAA you don't even have to use more power.

Man, must be a shock to the Swiss, that the FAA, that terrible agency that certifies people after cheap training, was actually faster ... again.

And if somebody is really interested in VRS, I found this from NASA (http://rotorcraft.arc.nasa.gov/publications/files/johnson%20ahs-sf2004.pdf).

And for heavens sake yes, I will call it from now on FVRS with a descent rate way beyond the lightly shaded area. You win.

[Devil 49]

It's been decades since I thought about fixed wing stuff, but doesn't the 'school' solution to VRS seem very similar to an airplane departure stall book answer?

[Rotorbee]

You will not believe what found the way on my desk.
There is a long interview with Vuichard in the Freiburger Nachrichten from the third of march. A local newspaper , but since it is in black and white, it must be true ... with a picture of the recent crash in Hawaii (which had nothing to do with VRS, but that's journalism).

Apparently many have died in VRS with billions of dollars (I do not exaggerate, it‘s written there) in damage.
"They" must have covered up thousands of VRS accidents and told us for years lies about the cause, like engine failures, cables, CFIT or other almost impossible ways to crash a helicopter. Bad that, very bad.
The FAA has become aware of him and has allowed him to speak at HAI Expo 2016.

Therefore my friends of bad faith, you must now bow your head in remorse, for you will never again question the Great One. Because it is written in the Holy News that his own words were: „Das kommt ins Fliegermuseum in Washington“. In plain English: „This will be in the aviators museum in Washington“ (probably the A&S Museum or they open one for him alone).

Probably his portrait will hang above the other not so great stick jockeys. Da Vinci himself will paint it. Resurrected by the Pope just for this unique occasion. The new millennium has its hero.

Apparently he found his technique 28 years ago. That is still after some of our colleagues here have known it, but hey, what's a few decades between prophets.

I will now ritually burn my helmet, license, bush pilot belt buckle, log books, Prouty, Coyle and all the other heretic books and hope that the great one will one day choose me to be his humble disciple.

And that one: "Never has a operational procedure been named after a person". No kidding. Who would call a procedure after himself?

But let's give the man a break. He will be 60 this year and his flying days are more or less over. He will now embark on a crusade around the world to save us all from doom (Coming soon in a hangar near you).

Hail Cross Control Recovery, for VRS is the mortal sin.

[Vertical Freedom]

Thanks 4 der gude larff Rotorbee...I almost had to change nappies I laughed so damn hard. Undoubtedly the Grand Mashter Flash Vulcan technique will all save us one day from an early grave (NOT) :ugh: as the far greater One; once said...'if it ain't broke don't fix it' :eek:

Moral of the story....if You find Yourself in VRS or IVRS then; leave power on or apply more to the red line, at the same time give a big pole forward & maintain some heading of sorts, until You fly out of it :ok: works every-time :8 every bleedin' time :E

Happy Yappy stay Happy :bored:

[Rotorbee]

Oh VF, I am so disappointed that you don't see the light. :=

Admit your sins. Your meagre hills are nothing compared to the mighty Alps where the Great One had his revelation. You will from now on preach cross control or the Yeti will be lurking in the shadow one day and barf on your shoes. :=

Now let us pray ...

[Lonewolf_50]

As requested, Rotorbee ...

Our Vouchard
who art in hover
Settling be thy bane
Thy cyclic come
Thy flight undone
Striking earth
Plunging down from the heavens
Give us this day a pedal slide
And forgive us our descent rates
As we forgive the CFI's who smote our pates
And lead us not unto the hillside
But deliver us from the vortex

[Jimmy.]

HjeRSDsy-nE

[Ascend Charlie]

Excellent bit of filming there, shows the flows beautifully.

[aa777888]

Wow. Best video I've seen in a long time. Brilliant use of the spray system. Bravo!

[newfieboy]

Awesome,
I'm flying an AS350 at the moment on forestry spray. Can really relate on what's going on. We're going max gross off the deck sometimes every ten minutes. Like tonight's session wind is calm but enough to be a tad downwind in the turns. Only way to spray the block due environmental. Can really feel the bump as you go through your vortices at the start of the line.
Another tool in the survival kit, especially tree tops heavy. The lack of height lost is very appealing.

[jellycopter]

Great images, rousing music, proves nothing. Where are the corresponding images of a regular IVR recovery for scientific comparison? Still not convinced.

[Vertical Freedom]

Nice video :ok:
Undoubtedly the Grand Mashter Flash Vulcan technique will all save us one day from an early grave (NOT) as the far greater One; once said...'if it ain't broke don't fix it'

Moral of the story....if You find Yourself in VRS or IVRS then; leave power on or apply more to the red line, at the same time give a big pole forward & maintain some heading of sorts, until You fly out of it works every-time every bleedin' time


Happy Yappy stay Happy :cool:

[[email protected]]

jellycopter - 100% agree - at best that was a quick recovery from IVRS, nowhere near full VRS.

[yellowbird135]

...but the thing is....in day to day ops how often do you encounter fully developed VRS?
In my experience, in the day to day ops, you notice immediately something is not right and you act.....this is mostly in the initial phase of VRS.
Now, the reaction on brain stem level is to dump collective, drop the nose and fly away.
I think it requires a lot of effort and training to make this technique your 'brain stem' response.....
I do think however that this might be a better approach to recover from it..
Let's see how the company training dept. feels about it...not in the sim but in the real thing..

[[email protected]]

...but the thing is....in day to day ops how often do you encounter fully developed VRS? Mr Vuichard seems to imply it is a regular occurence, hence his crusade to prevent loss of life from VRS accidents.

However, we don't actually see many VRS accidents, there are far more CFIT or power-settling accidents.

Whilst I agree that recovering from IVRS early is a good thing, it is far better to avoid it in the first place by planning and calculating performance before flight and avoiding the conditions where IVRS might occur - it's not difficult to do.

[Non-PC Plod]

Situational awareness is the key, and that usually comes with experience (as well as planning/briefing). I had a great example last week - I selected the AHRS to "DG" instead of "Mag" before startup to see how long it would take the student to see that something was not quite right.
45 mins later....(and with a big yellow HDG box on the PFD all this time), we were going for a hover OGE 1000' AGL as previously briefed. The wind indication on the PFD was now well and truly corrupted, showing about 180 deg out. But any check of groundspeed versus airspeed would show that we were 10-12 kts downwind (as per the weather forecast discussed at the brief).
Of course I could see all this unfolding, and I was ready to shove the nose forward (sorry M.Vuichard!) as soon as the vertical speed started to get out of the comfort zone. But, you would expect any competent and aware pilot to have noticed one of the many clues that were there all along, and we would never have got into the situation.

[ShyTorque]

I'd say the demo is more like what I'd call "settling with power" (i.e. running out of enough power to arrest a vertical descent) and flying out of it by putting the main rotor laterally into clean air to the side, rather than by a transition straight ahead.

It certainly doesn't look anywhere near as exciting as the fully developed VRS that I experienced, which involved quite rapid pitching, rolling and yawing.

[[email protected]]

It certainly doesn't look anywhere near as exciting as the fully developed VRS that I experienced, which involved quite rapid pitching, rolling and yawing. and that is the danger of this 'technique' - people might think this is a magic bullet to save them from real VRS which it most certainly isn't.

[Hughes500]

I am perhaps not the most experienced pilot on this forum but that video DOES not show VRS. As for pulling full power yes that will possibley get you out of IVRS but not fully developed. I know I have said this before but as a junior instructor one of my students had made 5 normal recoveries from IVRS using the normal stick the cylic forward technique. For someone unknown reason on the 6th go with a ROD of around 800ft a min with the cabin shaking, pitching and rolling the student pulled full power. Well fu.k me the result was what felt like an 80 degree nose up with the ac falling on its tail. ( so Mr Vulchard please explain that ) the vsi hit the stop at 3k a min. As for recovery I had the cylic on the forward stop, nothing happening, lever fully down and still falling on its tail. last resort was full pedal, then again wtf now facing 80 degrees pitch down and looking at the ground hurtling up. Slowly pulling power and rear cynic. I guess we missed the ground by about 200 ft. Not really sure how the rotor head stayed on the heli. So I was undoubtedly very close to full VRS when student pulled full power. This caused instantaneous fill VRS so I do not see how pulling full power and lateral cylic with pedals would work. But always happy to hear from those with more experience. Sorry that video shows nothing !

[[email protected]]

Hughes500 - and your story correlates exactly with Shy's and many others who have experience full VRS.

Mr 'magic-technique' Vuichard is clearly not the aviation God he professes to be - perhaps he is just someone looking to make a name for himself by selling snake-oil to the unsuspecting.

[Bell_ringer]

...on the 6th go with a ROD of around 800ft a min with the cabin shaking, pitching and rolling the student pulled full power. Well fu.k me the result was what felt like an 80 degree nose up with the ac falling on its tail. ( so Mr Vulchard please explain that )!

Well, the technique isn't about purely pulling power which on it's own would make the situation worse, the key is pulling power and simultaneously pushing the power pedal and rolling to the opposite side (ie left peddle and right roll in a yank machine and the opposite in a flying bus).
It's the roll assisted by the the tail rotor drift that helps you get into clean air.

[Washeduprotorgypsy]

Well first off I salute the entrepreneurial spirit of the whole technique and its"commercial" application.

Secondly, making the analogy with blowing smoke rings with stage of vortex development. I think VT can blow smoke but I'm not sure the ring part makes it past the end of his nose. Whereas everyone else on the forum who has submitted a more visceral response has experienced being entrained in the smoke rings of Gandalf himself blown clear across the room or to the base of the mountain as it may actually be.

Not sure the technique is new at all within the vertical reference community, but understand the outcry at trivializing VRS for the less experienced who might be tempted to disobey tried and true descent rates, in favour of faster productivity (i.e "ego posturing") because the VRS dragon has been slayed by the "VT two step" into the 300 foot hole/gully.

I don't think the technique is without merit just that it is a last line of defence in steep and slow(big trees,confined gullies, downwind, longline) situations versus a healthy respect for traditional descent rates around 300 fpm.

[Hughes500]

Washed
300fpm ? thats not even close to IVRS. can demonstrate 600 fpm vertical descent in a Hughes 300, pull power and she climbs back out of it
In the video I doubt the Lama has much more than 600 to 800 ft ROD
Anyone on the forum a test pilot at Boscombe Down with an ac with the kit on it to prove or disprove the theory. I don't see how you can get an ac in VRS ( say 1200 ft a min ROD plus ) can suddenly be stopped within 20 to 50 ft

[Washeduprotorgypsy]

Washed
300fpm ? thats not even close to IVRS

Yes, precisely, there could be some wiggle room in there for a sleepy brain ,flabby biceps and a big pitch pull at the bottom depending on all the factors. However the time and distance verticalled is so short why rush it?

[nigelh]

Well it certainly looks like this guy has ruffled some feathers !!!! No surprise that it is the usual crew of old school pprune resident experts ( you know who you are !!) who are the most dismissive . It looked clear to me by the accelerated RoD combined with the reversal of spray pattern that the helicopter was indeed just into VRS and the neat " side step" certainly looked to bring it to an abrupt end ..... Far quicker than forward cyclic I thought and with less height loss . So wouldn't it be better to actually learn more about this idea and see if it really is as good as they say ?!! It would be relatively easy to pitch the two recoveries head to head .....that way we may make things safer and maybe even prick some inflated egos at the same time 👍👍. ( or God forbid prove them right and never hear the last of it !!!)

[Vertical Freedom]

All opinions are welcome here.............as for the (magic self labeled) Vuichard technique; my Mountain colleagues & I have tried many, many times, sure it works OK (just) during the onset of a pussy footed SWP or IVRS , but once Your in a full blown skid mark serious VRS; then the Vuichard technique is as useful as licking Your microphone wind sock for a recovery. Be warned the Vuichard technique is Bollocks, it won't do diddly squat for you in full blown VRS.

Moral of the story................stick to what works & you'll live longer; :ok:

'If it ain't broke? Don't fix it'


When Your in VRS:
1. immediately & abruptly Pole forward (a good hand full of forward Cyclic)
2. leave Power (Collective) applied &/or add some more to the red-line
3. keep her straightish with pedals

.........works like a charm, every time! Tried, tested, proven; too many times to count :D

[[email protected]]

Nice try at stirring it Nigel - please carry on.....those that want to believe Mr Vuichard's fantasy can continue in ignorance of real VRS if they like.

[Jabberwocky82]

What is the reasoning for it to be a better technique? Surely the rotor disc cares not which direction it flies to find clean air? Is it the added thrust of the tail rotor which is meant to help compared to the normal poling forward?
What's the physics behind it?

[[email protected]]

What's the physics behind it? there isn't any.

All the pretty videos and flow patterns show that this is not a recovery from VRS, it is simply using power to fly away from the incipient and very early stage, long before full VRS has developed. And you are right, the disc doesn't care which way the clean air is coming from - in fact if you have any forward speed then moving forward is the quickest way to reach undisturbed air.

[Thomas coupling]

Firstly,
I'd like to congratulate Mr Vuichard on the making of a very professional film about crop sprayers.
The colours, backdrop, photoshop and music (especially) make for a very convincing story line................

until you realise this is one seriously FUC*ED UP commercial.

Either there is some meaning lost in translation between Mr Vuichard's interpretations and technical languaage or Mr Vuichard is one helluva'n ignorant pilot.
Nothing wrong in being an ignorant pilot - (one just posted on the 10th)....but it's best if they fly quietly out of harm's way somewhere in the boon docks chasing wart hogs.

We have been round the buoy with this particular Mr Vuichard before and as long as he continues to promote a very very dangerous message to those in the helicopter community that this is the gospel when it comes to VRS - I will continue to correct him.

Let me list facts and plead with the 'converted' that this message is WRONG, so very WRONG.

1. VRS is a fully developed aerodynamic state where the controls of a helicopter do not respond normally. Therefore adjustments/ corrections to these controls are sporadic.

2. VRS by definition includes a RoD in excess of 75% OF THE DOWNWASH SPEED OF THE MAIN ROTORS. this means RoD's in excess of 300,400,500 feet per minute - to start with and can reach thousands of feet per minute.

3. VRS is exacerbated by PULLING POWER. It accelerates stall.

4. Incipient VRS [IVRS], is not VRS.

5. Alternatively, flying controls react normally during IVRS.

6. Departure from the airstream beneath the tip path plane will diminish IVRS. This is normally achieved using the cyclic in either a sideways or forward direction. Departure to the side, rear or front of the vortices removes the cause.

7. IVRS rarely if ever exceeds 300 fpm.


Inaccuracies in the video:

(a) There is an "N" in Robinson.
(b) The subject matter he refers to has an "I" missing from the mnemonic: "VRS". The video would then make sense.
(c) A minimum height loss of "20-50 feet" cannot be achieved during VRS as the a/c is descending hundreds if not thousands of fpm.
(d) the audio suggests pulling power initially. This will of course accelerate loss of lift developing at the root, further aggravating the RoD.
(e) None of the controls would respond to the pilot's inputs if the demo actually showed VRS.

For those out there who wish to accept this video in its entirety - as gospel. You are living on borrowed time. It is essential you grasp the fundamentals of IVRS and then VRS before you even think about attempting to emmulate these manouevres for yourself.

Vertical Freedom lives and breathes the perfect environment for VRS in that rarefied atmosphere up there in the mountains - his comments require serious thought and consideration - because he is of course: correct.
As for Crab and myself who taught this for a living...................

[Rotorbee]

Well, it does not stop and it never will. For the Swiss and Robinson he is a hero.
I find it rather funny to call that thing in the video a VRS. As we have seen in his other videos in front of the Eiger, Mr Vuichard isn't to open with a view on the instruments. Not even in free fall he would have reached the RoD he claims in that time. The same with this Lama. Nice pictures, but never a VRS, one needs a few more feet to get into VRS.
I don't want to be in a helicopter that had a stop of a RoD from in excess of 3000 ft/min to zero in 20 feet. That is better than any quickstop I ever did.
It is strange, that Vuichard is so fixated on this problem. I can recall just one accident in Switzerland where VRS was the cause. In that case (the one with the REGA Agusta) the pilot did not realise what happened until he reached more than 900 ft/min RoD and > 20 kts and the IVRS started. Pulling power aggravated the situation, therefore he was quite close to a pretty good VRS.
I wonder if Vuichard bent a few ships in his lifetime with VRS. Otherwise I can not explain, why he is making up terrifying numbers of accidents that just are not true.
What is this man trying to do?

One thing in the Agusta accident final report I find interesting. They wrote, that some light helicopter manufacturers are evaluating a alternative method = Vuichard + Robinson.
The optimal recovery technique is set by the manufacturer. No Vuichard for Agusta, ups, sorry, Leonardo.
The recommendations do not include the Vuichard technique but a warning of some audible form from dangerous combinations of airspeed and RoD. Something I think is a very good idea and would probably completely eliminate VRS accidents. Much better idea than listening to a self-proclaimed prophet on a crusade against imaginary windmills. But why haven't they done that. With modern electronics this would not be a problem. Probably because it isn't the number one killer of helicopters. More number 347.

[nigelh]

You guys may well be right and i agree ( and bow to his professionalism in this field ) with Verticals " if it aint broke dont fix it " !!
I would still however like to see a proper comparison of the two techniques, as it may be that the pilot doesnt have the room infront and below to pole forwards and dive due to obstacles . Either way it seems that there are two groups of highly experienced pilots who disagree which can only confuse the rest of us mere mortals !! If he is wrong then his theory should be disproved and he should stop touting it around !!!

Thanks Crab ....a decent cast always gets a rise from the old TC Trout !!

[Paul Cantrell]

I would still however like to see a proper comparison of the two techniques, as it may be that the pilot doesnt have the room infront and below to pole forwards and dive due to obstacles .

I regularly teach both techniques in R44s, and less frequently in B206 and R66. My typical recovery is from sink rates of 1000-1700 feet per minute. I have been in VRS in an R22 that pegged the VSI, but I guess I'm not good enough to nail the downwash as well as that pilot could; I've never been able to peg the VSI myself - I tend to fly out of it before I can get those kinds of sink rates.

I'll also mention that a while back Nick mentioned that sink rate to achieve VRS varies with disk loading (which affects downwash velocity) thus a light disk loaded machine like most pistons will be in VRS at a lower sink rate - he had calculated that the R44 was in VRS @ 800 ft/min. So we have the issue that the least experienced pilots are flying the machines that are the easiest to get into VRS.

In any case, I do indeed see quicker recovery using Vuichard than traditional... typically 40-50 feet vs 150 feet. It is quite abrupt - it's like hitting a speed bump as it shoves you out of the downwash. It's also slightly less comfortable for student pilots because you then have to recover from sideways flight which can be disorienting for a low time student pilot.

The traditional method also has a problem for low time pilots in Robinsons - we spend a lot of time teaching them not to do aggressive cyclic pushes in order to avoid low gee, so it feels weird for them to do an aggressive cyclic push in that situation. This can cause very slow recoveries from VRS..

My suspicion all along is that the faster recovery I see with Vuichard is because I'm not lowering the collective, the way I am with the traditional technique. It would be interesting to understand what Vuichard would do with a deeply stalled rotor system, however in 30 years of teaching probably tens of thousands of recoveries from VRS, I've never felt any indication that the cyclic was losing effectiveness. So it might be that if I did the forward recovery without lowering collective I would see the same 40 feet (but I'm somewhat skeptical that I would).

Of course, we shouldn't be recovering from fully developed VRS anyway, because what the heck were you doing all that time the sink rate was increasing??? My general advice to new pilots is that if they are on approach and they feel that sinking feeling down around ETL speeds, they should simply go around - chances are fair that they had a tailwind or otherwise screwed up the approach. If you detect it while you're right around ETL speed, you don't have to gain very many knots of airspeed to be flying again.

If it's an OGE hover it's a little different, but in that case you're presumably trying to hold a specific altitude, so it's pretty obvious when you start to sink... long before you hit VRS you should have fixed the sink rate...

[Reely340]

When Your in VRS:
1. immediately & abruptly Pole forward (a good hand full of forward Cyclic)
2. leave Power (Collective) applied &/or add some more to the red-line
3. keep her straightish with pedals

.........works like a charm, every time! Tried, tested, proven; too many times to count :DBeing the newbie that I am I don't get it: The only difference I see is that the Anti-Vuichard faction advocates forward stick, whereas Vichard likes sideward stick better.

Both recommend to "leave power applied" (at least VF did in post #226) and keep her straight with pedals.
I don't see any difference, besides maybe rolling a heavy airframe might need less energy that pitching it.

What am I missing, why is it so extremely important which direction I ram the stick to, to end full VRS?

[Paul Cantrell]

Being the newbie that I am I don't get it: The only difference I see is that the Anti-Vuichard faction advocates forward stick, whereas Vichard likes sideward stick better.

Both recommend to "leave power applied" (at least VF did in post #226) and keep her straight with pedals.
I don't see any difference, besides maybe rolling a heavy airframe might need less energy that pitching it.

What am I missing, why is it so extremely important which direction I ram the stick to, to end full VRS?


For Vuichard, I was taught that if I'm at a low power setting to increase to a moderate climb power and use power pedal to maintain heading - the idea being to make sure tail rotor is producing enough thrust to shove me sideways out of the downwash. Also, you want to tilt the rotor in the direction of tail rotor thrust, i.e. in an American helicopter bank right, in a French helicopter, bank left... so that main rotor thrust and tail rotor thrust are working together.

[Thomas coupling]

Reely 340.
The big big difference is that Vuichard is calling his technique: recovery from VRS.
The lesson to learn here reely is that he is never in VRS. He is only ever demonstrating (in all his shots) how to recover from IVRS.

There is a HUGE difference.
Quite a few helicopter pilots have experienced IVRS, they probably aren't 100% sure what is happening but they manage to scramble out of it - somehow. And they live to fight another day.

BUT when you enter FULLY DEVELOPED VRS, your helicopter takes on its own persona and you may well become an unwilling passenger.

We used to teach FDVRS in the mil - many moons ago. Entry heights were greater than 8000 feet due to the height lost. Some a/c were lost before the mil put an end to it all.

But I will never forget the characteristics of FDVRS:
yawing, pitching, rolling - uncontrolled (yawing was dependent on the vortices blowing thru the tail rotor area).
RoD: extreme figures - 2,3,4000+ feet per minute. As some say- the gauge was off the clock - pegged!

Recovery must be forceful and sustained - fwd cyclic (20 degrees plus and lower the collective, maintain pedals central.
[If you bottom the collective - autorotation is a recognised way of coming out of VRS]. You cannot get VRS in an auto state - aerodynamically impossible.

So - all these pretty videos are bull****, UNLESS there is a loss in translation and Vuichard means IVRS and not VRS.

One simply cannot recover from FDVRS within tens of feet - absolute complete and utter bollock*.

How does one sift thru this minefield of cross purpose advice and guidance:

Simple, remember this:

If you are experiencing a gradual and increasing RoD.
A/c starts to vibrate.
Controls gradually feel less responsive.
Speed is low (<20kts ish - no fixed figure).
You are almost certainly entering IVRS.

Response - gentle nose fwd atleast 20 degrees and HOLD, gently lower the collective (IF height permits). Sorted.

If height doesn't permit: nose fwd 20 degrees and apply collective to a sturdy RoC setting - this is called the "minimum ht loss technique".

IVRS will always allow the pilot to respond without much of a rush.




YOU HAVE TO ALLOW IVRS TO CONTINUE if you want to experience the true VRS.
And believe me when I say - you will never forget what that feels like (if you live to tell the tale), because you'll need hundreds possibly 1000' to recover.

Here the recovery technique is the same but because you are running out of height - the minimum ht loss technique is advised, in this order:

Nose down atleast 20 degrees and HOLD (to regain ample fwd speed).

THEN

Raise collective to max RoC setting to get away from terra firma!

Look back over this very long thread to learn more. And spread the word that Vuichard is talking bollox. [Unless of course he actually is talking about IVRS and not FDVRS].

[FlimsyFan]

It is indeed quite mind boggling to the lowly 250hr private pilot. As alluded to, Robinson are now promoting the Vuichard as their recommended recovery.

During the Robinson Safety course, having gone through the theory we went and flew the recovery with Tim Tucker from RHC in an R66.

With 4 POB, I have video recorded from the back seat showing ROD at 1900 ft per min, and the thing was shaking and rolling all over the place. The recovery certainly seemed massively swifter than the 'traditional' technique as demonstrated, but I'm very reluctant to dismiss the views of the highly experienced guys here.

It seems to me with the numbers we saw, this must have been way past incipient; however as a low time pilot, my conclusion is to work very hard to avoid the basic ingredients for VRS in the first place - after all, it's fine saying that you can recover in 100ft from fully developed VRS when you start at 3500 ft, something else entirely when you f**k up a downwind approach into a confined area and the job goes tits up at 150 ft.

As someone else commented, I will probably stay with the Vuichard, just because rapid forward cyclic + R66 has been known to lead to much worse than VRS...

Very interesting discussion tho.

[nigelh]

Well maybe I am wrong but I wouldn't call 1900 ft sec incipient. There is far too much evidence here to just call it " Bollox " TC . Have you had this recovery demonstrated to you or done it yourself ?? If it didn't work ... Well tell us !
Everyone here just wants to learn ..if this really is a better technique then we should investigate it surely ??? I personally have no idea having never been in VR in 35 years and have no intention of doing so training or otherwise !!

[Washeduprotorgypsy]

Robinson could be supporting the technique because they are making the tacit assumption that most of their pilots have a uncanny knack for making downwind approaches. In which case, the sidestick makes sense.

Upon further review of that well done and beautiful video It is interesting to note that in the first "main showpiece" clip explaining the "visualization of the airflow" at 50% slow mo. It seems to be that the RoD is high enough that the recovery takes place in the turbulent wake state , punching right through the vortex ringstate, he falls right through the donut centered on the tip path. The lama is getting clean air and able to reverse the flow with pure grunt, escaping a redeveloped vortex with lateral cyclic. It would be interesting to see the scene reshot slowing the initiated descent so that the pitch pull could tease the strength of the building vortex ring , just right, without falling through it. .....like we are ever going to see that clip. The rest of the clips show IVRS nicely.

Maybe it's just me , but with the charts depicting modern day disc loadings as making 500 - 1000 fpm vertical descents acceptable. I' m not sure they really factor in the rate of vertical deceleration and power application or the recovery profile, so as not to stir a dragon. At the extremes we have the V22 which according to its induced velocities should be immune to vortex ring in moderately aggressive conventional helicopter flight. Somehow I don't think they baby it around on short final because it's 'spensive.

[Hughesy]

Isn't it more important to recognize the onset of settling and recovery immediately rather then allowing full blown vrs to develop?
Regardless of what recovery technique used?
Personally I would be using the normal forward cyclic way.
But recovering before if gets more interesting.

[FlimsyFan]

Had a quick look through videos from training the VT, and max ROD you can just make out on the panel is 2400ft/min.

But then I accept that all the high time guys here have the tacit understanding that I am a **** pilot in a **** helicopter and therefore don't much care what I have to say.

[Heliringer]

Had a quick look through videos from training the VT, and max ROD you can just make out on the panel is 2400ft/min.

But then I accept that all the high time guys here have the tacit understanding that I am a **** pilot in a **** helicopter and therefore don't much care what I have to say.

Hi mate, is there any chance you can post the video here or youtube?

Slack day at work here and we are looking Robinson VRS stuff up. The highest ROD I've seen so far is about 500fpm, although it is hard to see the dials sometimes. It would be interesting to see this at 2400fpm.

[[email protected]]

I have a suspicion that the demonstrations don't give a real world perspective - in the classic VRS scenario, you are already pulling a lot of power because you are either approaching or trying to establish an OGE hover.

The demonstrations seem to involve lowering the lever to initiate the descent, leaving you a fair surplus of power to recover.

Nick Lappos has always said that with a powerful enough helo, you can muscle your way out of VRS because you are able to overcome the massive increase in rotor drag.

So the difference between going from a low/medium power setting to max power (as prescribed by Vuichard) is going to be greater than going from almost max power to max power - this might help explain why these artificial setups seem to work well.

When we see a video of full blown VRS - with a high power setting to fully aggravate the situation - being recovered in tens of feet, then I might start to believe but not until then.

For those who have done the Robinson course, do they only show this in the R66 or do they do it in R22/44 as well? I only ask this because of the extra power available in the 66 over the 22/44.

[aytoo]

Hi Crab! Long time no speak...

What an interesting thread! M Vuichard, FWIW, is an examiner with the Swiss CAA, with a long history of long lining and mountain flying. Not directly defending his technique - I have insufficient data for that. However, I do think it is one of the more interesting concepts that I have seen in my limited flying career (1983 - 2011).

Like others on here, I have always had a healthy respect for VRS, and used to teach my students to listen for/feel the aircraft growling at you as a warning - as they all will on a poorly flown, low-speed, and steep approach.

I also recall seeing an explanation of the origins of the terms VRS and SWP, but cannot now locate it. IIRC it has the US Army calling it one thing, and the USN the other - and no agreement on a common way forward. Imagine! (Quickstop v fast stop springs readily to mind).

All I will say on Vuichard is to keep an open mind. Until we see quality data from an unimpeachable (and not-for-profit) source, shall we consider that he might - just might - be on to something?

[[email protected]]

Hi aytoo, the SWP was used to describe two different conditions IIRC, both VRS and overpitching due to lack of power margin for OGE hovering.

I think the confusion arose since both conditions, when experienced relatively close to the ground, result in a broken aircraft and often the crew from a very heavy landing.

SWP can lead to VRS since you don't have enough power to hover and a slow or zero IAS descent with high power applied - often with Nr decay due to power limiting - is the result - a perfect recipe for VRS.

What I would like to know is if these Vuichard demonstrations ever show a direct comparison, in the same conditions, of the traditional recovery vs the 'technique'. That would be a good starting point for a claim of superiority.

Like so many things these days, it is easy to make a bold claim, supported by 'scientific proof', which turns out to be wrong because the 'proof' has been fudged to support the claim.

As most of us agree, the answer is prevention - we are bickering about the 'cure' which may not be suitable for all cases of low speed descents.

I won't hold my breath waiting for unimpeachable proof:ok:

[212man]

I'm with VF, Crab, ST, TC etc on this. An analogy is a Fixed Wing spin - you can centralise the controls at the first sign of an incipient entry, and recover immediately, or you can be in a fully developed and in some cases if mishandled, a second high rotational mode, and take hundreds of feet to recover. Occasionally running out of height, and requiring a swift exit and the use of a parachute!

[Freewheel]

How long will it be before some of you guys realise that ALL of the techniques discussed in this thread (including the Vuichard) are useful and work as advertised.

And............


Understand which technique to use under the circumstances you find yourself in.


Using one technique early may prevent the need for the use of an alternative technique later, BUT most of all;


Situational awareness is key.

[Thomas coupling]

http://www.pprune.org/rotorheads/67635-power-settling.html

for starters

[Thomas coupling]

Every time these subjects come up:
VRS
SWP
TR failure
LTE
LTA
et al....a lot of pilots still seem confused.....where is this industry going?

What happened to standards and the flow of knowledge.....

[Vertical Freedom]

Certainly I am no aeronautical scientist, nor engineer. As an open minded Instructor & professional Commercial Pilot I wanted to try for myself & if proven effective adopt this technique for myself. So I have tried the Vuichard technique in the real World; practically many, many times in both a piston (at <5,000,) & turbine machines (> 10,000') & found this technique does NOT work when in full blown VRS with ROD above 3,000' ~ VSI firmly pegged @ 3,000'? In mild SWP & IVRS yes, it does work, OK! :D

Remember You get into VRS because of a high ROD, power on & zero airspeed, so the priority (for me) get back some airspeed by poling forward....VRS problem solved :cool:

So I will surely be sticking to the tried & proven method taught to me & I am assuming the vast majority of Pilot's here. :ok:

Happy Landings!

[Reely340]

Remember You get into VRS because of a high ROD, power on & zero airspeed, so the priority (for me) get back some airspeed by poling forward....VRS problem solved :cool: Please outline why "poling sideward" does not help as well as "poling forward". :8

[Thomas coupling]

You get into VRS because of a high ROD, power on & zero airspeed,

Not quite.
A RoD generally around 300+fpm (not gospel but usually the case).
Power On - yes.
Zero airspeed - not quite - you could have low airspeed on. (<20kts ish).

Poling sideways to obain the sort of recovery speed one is after would require signifiacnt nose left/right and maintaining it - not very comfotable at all. Better to nose down which the a/c is designed for from a slipstream perspective.
But technically as long as you exit the turbulence beneath the rotor disc - left/right/back front - you will recover.

[Reely340]

Poling sideways to obain the sort of recovery speed one is after would require signifiacnt nose left/right and maintaining it - not very comfotable at all. Better to nose down which the a/c is designed for from a slipstream perspective.
But technically as long as you exit the turbulence beneath the rotor disc - left/right/back front - you will recover.But maybe a rather longish object like a helicopter fuselage can be rolled with less force, or to a greater angle than it can be pitched? Like a rod 1" x 1' can be rolled more easily/faster around its longitudinal axis that it can "propellered" around is center.

What if Vuichard only discovered, that tilting the helo to the side some 30° can be done faster than pitching it 30° forward, especially when you do it to the very side your tail rotor is aready pushing you to? :ok:
(that might be the reason he advocates right roll + left pedal for left turners)

[Thomas coupling]

Whoa cowboy.
Don't over egg the pudding.
Stick to basics in situations like this.
I would wager a large bet that you are far more proficient and comfortable with 30 degrees nose down than 30 degrees sideways slip for a prolonged period.
Don't second guess what TR vectors are doing about the horizontal - eeek.