A different take on Vuichard

[Robbiee]

So, normally whenever an instructor and I have done VRS recovery (both techniques) its always been at like 2,000' agl. Well recently, an instructor had me do it at 100'.

Now (of course) we didn't actually enter VRS at just 100', but he did have me do the side step recovery maneuver at that altitude while on a decently fast approach, saying that (in reality) that's more likely where this technique shines, as (of course) 100' is waaaay to low for the traditional one.

Anyway, it was a lot of fun, and I'm glad I finally got to experience a more practical way to practice this maneuver.:cool:

[SLFMS]

That would be a firm no thanks from me.

Instructing VRS, one thing I learnt is how unpredictable it is sometimes you couldn’t find it sometime you flirt with it and other times you got a hell of a ride.

I wouldn’t be messing with the incipient states at that height lest they become fully developed.

In my opinion VRS is quiet easily avoided and recovery is chasing the horse after it’s bolted.

[[email protected]]

So the Vuichard myth is still being taught.......and believed......

[hargreaves99]

Is it a myth? I understood it was a valid technique, although not one which the CAA allow to be taught.

[jellycopter]

So, normally whenever an instructor and I have done VRS recovery (both techniques) its always been at like 2,000' agl. Well recently, an instructor had me do it at 100'.

Now (of course) we didn't actually enter VRS at just 100', but he did have me do the side step recovery maneuver at that altitude while on a decently fast approach, saying that (in reality) that's more likely where this technique shines, as (of course) 100' is waaaay to low for the traditional one.

Anyway, it was a lot of fun, and I'm glad I finally got to experience a more practical way to practice this maneuver.:cool:

Surely this is a couple of days early for April Fool’s? Or is it Darwinism in waiting?

[hargreaves99]

here is the previous discussion

https://www.pprune.org/rotorheads/626806-vuichard-again.html

[[email protected]]

Hargreaves99 - it is a valid technique only as far as getting away from IVRS is concerned and is no more efficient or effective than either just pulling power or just putting the nose forward a bit to gain speed.

If you remove either the low speed or RoD from the VRS equation then you won't go from IVRS to VRS and any sensible action is likely to achieve that.

Vuichard's 'technique' takes the RoD out by pulling max power - the rest of the manoeuvre , rolling and yawing isn't necessary.

It works for early IVRS only and will not save you from full VRS.

That's why the CAA think it shouldn't be taught.

[[email protected]]

Now (of course) we didn't actually enter VRS at just 100', but he did have me do the side step recovery maneuver at that altitude while on a decently fast approach, saying that (in reality) that's more likely where this technique shines, as (of course) 100' is waaaay to low for the traditional one.
So on a decently fast approach you are nowhere IVRS or VRS - what, pray tell, is the point in the sidestep manoeuvre?

Did he pull max power and then add a boot-full of pedal? What did the Tqmeter say (or MAP gauge indicate).

[mechpowi]

My experience is that the 'add full power" -part of the sideways exit method is not necessary for the exit of VRS. It's there to have all the power in use at the moment the rotor exits the VRS. The exit itself can be accomplished with SOME power applied. I guess that different helicopters react quite differently to VRS, the R44 beeing quite stabel in 1500-2000 ft/min descend where adding max power even for extended period of time does not help. The R44 stays responsive to the cyclic and, here my experience ends, would probably come out of VRS with any long term cyclic input even regardless of collective position. With other helicopters your milage may vary, especially if the cyclic authority is compromised.

[Robbiee]

Interesting reactions. Some of you think we entered VRS at that height, some of you don't see the point of demonstrating without entering VRS, and some of you don't believe the maneuver is even legit, lol.

Anyway, the instructor was one of these old guys, who's been flying/teaching for years, if that makes any difference, lol.

[[email protected]]

Anyway, the instructor was one of these old guys, who's been flying/teaching for years, if that makes any difference, lol. So am I and I see no point in pretending to be in IVRS to show a fairly basic manoeuvre to get you out of IVRS

[Hughes500]

In my humble opinion i dont think Claude has ever been in VRS ! Having been there once I can assure you adding power to step out made it worse not better !!!!

[Robbiee]

So am I and I see no point in pretending to be in IVRS to show a fairly basic manoeuvre to get you out of IVRS

So, I guess you feel the same way about, pretending to be in IIMC, just to show a fairly basic maneuver to get out, or pretending to have partial power loss, to show the fairly basic maneuver to get down with it, or pretending to have a 100' foot obstacle in front of you, to show the fairly basic maneuver to get over it?
:ok:

[[email protected]]

Or pretending to be a professional helicopter pilot just to create arguments on a website..............

[[email protected]]

So, I guess you feel the same way about, pretending to be in IIMC, just to show a fairly basic maneuver to get out, or pretending to have partial power loss, to show the fairly basic maneuver to get down with it, or pretending to have a 100' foot obstacle in front of you, to show the fairly basic maneuver to get over it?
:ok:
And as it happens, in those three situations you are putting the aircraft at the height and speed of the scenario you are simulating - your Vuichard demo had the height but not the speed so please tell me what you learned from it.

[Robbiee]

And as it happens, in those three situations you are putting the aircraft at the height and speed of the scenario you are simulating - your Vuichard demo had the height but not the speed so please tell me what you learned from it.

Well, given that the most likely scenario for getting into VRS on approach when you think your airspeed is sufficient, is because you're in a tailwind, doing this simulation with a good amount of forward speed was correct for that type of situation.

Anyway, I learned what it would look like to perform that maneuver at low altitude with forward motion, intead of the usual OGE hover at 2,000' agl.

Sorry if this offends your sensibilities, pal, but I haven't done anything new in a helicopter in a very long time, so it was a nice break in the monotony.

[Jabberwocky82]

I would not say it's a different take on Vuichard, it's more so the reverse. For instance, when longlining and moving your bucket into a dip site, if you feel any early stages of onset coming in, your natural reaction is to move the aircraft sideways. You have your head out of the door and that it the natural way to go - sideways. It's probably been used ever since we started lifting things on lines with our heads out the door.

Whether you believe in the Vuichard technique or not, learn how not to get in the situation and learn to identify the early stages of onset. It is good that you got exposure at a low height.

There is a video around somewhere of an incident where a Md900 fell off the top of a building in the Gold Coast in Australia whilst lifting air conditioning parts and got into VRS. The pilot used the side slip technique to gain control at the bottom of the 'fall'. He was/is a high time longline pilot from NZ/BC and would have no idea who Vuichard is, let alone how to spell it.

[Robbiee]

I would not say it's a different take on Vuichard, it's more so the reverse. For instance, when longlining and moving your bucket into a dip site, if you feel any early stages of onset coming in, your natural reaction is to move the aircraft sideways. You have your head out of the door and that it the natural way to go - sideways. It's probably been used ever since we started lifting things on lines with our heads out the door.

Whether you believe in the Vuichard technique or not, learn how not to get in the situation and learn to identify the early stages of onset. It is good that you got exposure at a low height.

There is a video around somewhere of an incident where a Md900 fell off the top of a building in the Gold Coast in Australia whilst lifting air conditioning parts and got into VRS. The pilot used the side slip technique to gain control at the bottom of the 'fall'. He was/is a high time longline pilot from NZ/BC and would have no idea who Vuichard is, let alone how to spell it.

Don't quote me on this, but I've been under the impression that the idea of this Vuichard thing was to adapt the long-line technique for those of us who don't do long-lining.

Anyway, until this recent experience I'd never seen a practical reason for this technique, since I never really spend any time in the OGE hover environment.

[SASless]

Now I never claimed to be the sharpest knife in the drawer but I always wondered about this accelerate forward to escape from IVRS/VRS as I was led to believe it was caused by descending into. a descending column of air caused usually be being slightly downwind and that pulling power only added to that problem.

Last time I checked most helicopters (smaller lighter aircraft as compared to the strongly powered behemoths that according to some can use power alone to escape....lowering the nose to accelerate gives a negative effective for ROC and demands more power which would add to the downward velocity of the air column.

The goal is to get out of the downward flow of air....and it seems intuitively obvious that the shortest direction to do that would be to either side rather than forward as in my mind the shape of that downward moving column of air is not going to be circular but rather more of an elliptical shape (longer fore and aft and narrower side to side).

Also...a turn into wind rather than extending your down wind approach with a higher ground speed close to the ground has undone many a helicopter and pilot.

I suppose the nice folks at the CAA don't care much for teaching Tail Rotor Emergency procedures using rotor rpm and collective when the pedals are not working as advertised either.

Does it matter what labels are affixed to the situation or recovery techniques or can we just talk about the effect of flight controls and applications of power, etc and not get hung up on the labels?

I can almost hear the near Gregorian Chant of Vulchard, Vulchard, .....GO!

[Robbiee]

Now I never claimed to be the sharpest knife in the drawer but I always wondered about this accelerate forward to escape from IVRS/VRS as I was led to believe it was caused by descending into. a descending column of air caused usually be being slightly downwind and that pulling power only added to that problem.

Last time I checked most helicopters (smaller lighter aircraft as compared to the strongly powered behemoths that according to some can use power alone to escape....lowering the nose to accelerate gives a negative effective for ROC and demands more power which would add to the downward velocity of the air column.

The goal is to get out of the downward flow of air....and it seems intuitively obvious that the shortest direction to do that would be to either side rather than forward as in my mind the shape of that downward moving column of air is not going to be circular but rather more of an elliptical shape (longer fore and aft and narrower side to side).

Also...a turn into wind rather than extending your down wind approach with a higher ground speed close to the ground has undone many a helicopter and pilot.

I suppose the nice folks at the CAA don't care much for teaching Tail Rotor Emergency procedures using rotor rpm and collective when the pedals are not working as advertised either.

Does it matter what labels are affixed to the situation or recovery techniques or can we just talk about the effect of flight controls and applications of power, etc and not get hung up on the labels?

I can almost hear the near Gregorian Chant of Vulchard, Vulchard, .....GO!

The thing about pushing forward to get out of VRS, is that we're always practicing it with a vertical fall from an OGE hover, where pushing forward does move you clear.

In reality though, it'd probably be more like that video they show at the Robby Course where the R44 is on a downwind approach to a rooftop, gets into VRS, hits hard, slides across the roof, then gets dynamic rollover and falls to his death.

He had forward movement, so probably didn't realize he was in it until too low, but thing is, with his already forward momentum, would pushing the nose forward even get him out of VRS?

Seems no one ever talks about this when it comes to the "traditional" recovery technique.

[Ascend Charlie]

Doesn't anybody fly an approach by maintaining an apparent walking pace over your toes? Positive forward motion (visually over toes and IAS), controlled rate of descent, aim point steady in the window. From 300' and 60kt, the decreasing airspeed makes the walking pace looks constant all the way to the hover where you have a REAL walking pace.

A downwind approach will have groundspeed apparently higher than indicated airspeed, something which should be detected well before losing translational lift. But people still fall out of the sky, and run out of left pedal, and do silly stuff. Like "Pretend" VRS at 100', and practising bleeding.

[Lala Steady]

Well, given that the most likely scenario for getting into VRS on approach when you think your airspeed is sufficient, is because you're in a tailwind, doing this simulation with a good amount of forward speed was correct for that type of situation. You are confusing groundspeed with airspeed chum. If you fly a downwind approach without realising it (unless the wind is very light and variable) you shouldn't be in the cockpit. If you know you are downwind you take extra care to avoid letting a high RoD develop.

​​​​​​​Whether you believe in the Vuichard technique or not, learn how not to get in the situation and learn to identify the early stages of onset. Prevention is always better than cure.

[Torquetalk]

In reality though, it'd probably be more like that video they show at the Robby Course where the R44 is on a downwind approach to a rooftop, gets into VRS, hits hard, slides across the roof, then gets dynamic rollover and falls to his death.

That is a horrible accident Robbie. The pilot made a bad decision to continue for the rooftop, when they had space and height ahead to recover. The commital point was much much later than than the clear acceleration into VRS. The aircraft was also stable in VRS and not pitching, yawing and rolling, so really good conditions to recover.

Having reached the roof, the pilot slid long from one side to the other and then hit a small barrier tipping the aircraft over the edge and death. It seemed to me that the pilot and pax could still have survived the initial bad decision to go for the roof if:

1) they had lowered the collective progressively and promptly and got the weight square down on the roof.

2) running out of roof, lift the collective and hop over the barrier, at which point they would already have been out of VRS because there was no sink rate - but possibly out of the performance envelope, so it might have happened again…

It was a pinnacle approach SE. If the pilot had recce’d and done a power check they might have realised that the approach was a NO GO.

And was there any performance planning pre-flight? I’d hazard not.

[212man]

In my humble opinion i dont think Claude has ever been in VRS ! Having been there once I can assure you adding power to step out made it worse not better !!!!
I’ve said it before - he’s a travelling snake oil salesman

[Torquetalk]

In my humble opinion i dont think Claude has ever been in VRS ! Having been there once I can assure you adding power to step out made it worse not better !!!!

The Vuichard video I have seen shows the aircraft in a stable state sinking through in its vortices. Lovely and stable, apart from the increasing ROD. But as you say, the aircraft can be all over the shop and it seems to me that the idea of an effective controlled cyclic sidestep and effective yaw input in that condition is a little fanciful.

And as one of the biggest risk factors is running out of power to control the accelerating sink rate, overpitching followed by proper ugly VRS renders the idea of adding of collective somewhat redundant. It is surely a way to get yourself killed in an aircraft that is at its performance limit or beyond.

[[email protected]]

One problem with discussing IVRS and recovery techniques is that the incipient stage is very variable and not binary - you can go from having the right figures on the dials to believe you are at the onset of IVRS, where pretty much any recovery works, to being much deeper into the void where application of power takes you from IVRS to VRS very quickly (as Hughes 500 alludes to).

The Vuichard 'technique' works at the very early stage simply because doing pretty much anything would remove you from the parameters of IVRS - he has just made a song and dance out of it.

[212man]

The Vuichard 'technique' works at the very early stage simply because doing pretty much anything would remove you from the parameters of IVRS - he has just made a song and dance out of it.

Exactly! A FW analogy would be to say that the way to recover from a spin is to add some power and lower the nose.

[Robbiee]

That is a horrible accident Robbie. The pilot made a bad decision to continue for the rooftop, when they had space and height ahead to recover. The commital point was much much later than than the clear acceleration into VRS. The aircraft was also stable in VRS and not pitching, yawing and rolling, so really good conditions to recover.

Having reached the roof, the pilot slid long from one side to the other and then hit a small barrier tipping the aircraft over the edge and death. It seemed to me that the pilot and pax could still have survived the initial bad decision to go for the roof if:

1) they had lowered the collective progressively and promptly and got the weight square down on the roof.

2) running out of roof, lift the collective and hop over the barrier, at which point they would already have been out of VRS because there was no sink rate - but possibly out of the performance envelope, so it might have happened again…

It was a pinnacle approach SE. If the pilot had recce’d and done a power check they might have realised that the approach was a NO GO.

And was there any performance planning pre-flight? I’d hazard not.

You seem to be assuming the pilot knew he was in VRS. He may not have, hence the decision to "continue yo the rooftop".

Anyway, the flight was intentionally flown downwind to get the required angle for the photo shoot, so I'm guessing they did their performance calculations.

Thing is though, Robby pilots are generally only shown VRS recovery from an OGE hover, so we don't know what it looks like when we have forward movement, thus the pilot may not have even realized it, until the very end when he went to pull power to land.

[Torquetalk]

You seem to be assuming the pilot knew he was in VRS. He may not have, hence the decision to "continue yo the rooftop".

Anyway, the flight was intentionally flown downwind to get the required angle for the photo shoot, so I'm guessing they did their performance calculations.

Thing is though, Robby pilots are generally only shown VRS recovery from an OGE hover, so we don't know what it looks like when we have forward movement, thus the pilot may not have even realized it, until the very end when he went to pull power to land.

The aircraft was next to a building. We see the acceleration in the video, taken at some distance and from above. I find it a stretch that the pilot was unaware that they were in a downward acceleration. In fact, I’d guess that the collective was pulled to check the acceleration and the low RRPM alarm went off. Then the pilot went for the roof to land asap. Not a good decision or IVRS response and pretty much locking in a bleak outcome.

Lot’s of supposition? Yes. But there is plenty of evidence to support that take
in the video, and you say it was a downwind approach. If that is true, then going for the rooftop with a big sink rate was extremely dangerous and perhaps indicative of poor training and certainly poor airmanship. Not trying to be down on the pilot, but they did also kill their passengers.

Perhaps the pilot did performance planning for that shoot and found… what?
WAT chart - check
HOGE power - I sincerely doubt it.

And without the latter, the approach should not have been attempted downwind.

Maybe it is also useful to separate out utility versus other kinds of flying. Moving out of the vortices sideways may be a trick that is up any low level utility pilot’s bag of tricks to catch IVRS. But I doubt it has much application for public transport. And may be a method that invites false confidence and risk-taking by hour-building photoshoots.

If the pilot really was unaware of the high sink rate, then they really should not have been doing what they were doing.

And when it started to go South, just follow the training: lower the collective a little and attitude at the horizon until airspeed is indicated.The escape route forward seemed fine.


Did IVRS in the sim for the first time in many years a while back. The TRE wanted to see more airspeed before recovery, but I saw 35 knots and that was good enough for me. It took several seconds. But surely that’s the point? See it developing and fix it. Apply the basic training and don‘t impede what should be an intuitive response.

As you no doubt know, training for VRS is done into wind on light or no wind days. Doing it downwind with a fair wind component is a different matter altogether. And may result in aircraft and occupants in a smelly heap.

[Robbiee]

The aircraft was next to a building. We see the acceleration in the video, taken at some distance and from above. I find it a stretch that the pilot was unaware that they were in a downward acceleration. In fact, I’d guess that the collective was pulled to check the acceleration and the low RRPM alarm went off. Then the pilot went for the roof to land asap. Not a good decision or IVRS response and pretty much locking in a bleak outcome.

Lot’s of supposition? Yes. But there is plenty of evidence to support that take
in the video, and you say it was a downwind approach. If that is true, then going for the rooftop with a big sink rate was extremely dangerous and perhaps indicative of poor training and certainly poor airmanship. Not trying to be down on the pilot, but they did also kill their passengers.

Perhaps the pilot did performance planning for that shoot and found… what?
WAT chart - check
HOGE power - I sincerely doubt it.

And without the latter, the approach should not have been attempted downwind.

Maybe it is also useful to separate out utility versus other kinds of flying. Moving out of the vortices may be a trick that is up any low level utility pilot’s bag of tricks to catch IVRS. But I doubt it has much application for public transport. And may be a method that invites false confidence and risk-taking by hour-building photoshoots.

If the pilot really was unaware of the high sink rate, then they really should not have been doing what they were doing.

And when it started to go South, just follow the training: lower the collective a little and attitude at the horizon until airspeed is indicated.The escape route forward seemed fine.


Did IVRS in the sim for the first time in many years a while back. The TRE wanted to see more airspeed before recovery, but I saw 35 knots and that was good enough for me. It took several seconds. But surely that’s the point? See it developing and fix it. Apply the basic training and don‘t start

As you no doubt know, training for VRS is done into wind on light or no wind days. Doing it downwind with a fair wind component is a different matter altogether. And may result in aircraft and occupants in a smelly heap.

The pilot was on a photo shoot with pax, so its not unreasonable to think that he just got distracted and didn't notice his increasing rate of decent. I mean sure, its easily evident from our perspective watching the video, but from his point of view,...?

Aa for false confidence promoting risk taking? Lol, we already have plenty of that with all these VFR jobs in VFR only helicopters requiring an instrument rating.

[Torquetalk]

As I said, he was next to a building - a nice lateral reference, had a variometer - on which the eyes needed to be scanning IN, together with remaining power in hand.

At the end of the day, the pilot got into IVRS and responded badly. And everyone died. I think it is a fair critique to say an avoidable event was caused by poor procedures and decision-making. The pilot was just another passenger along for the ride.

And most importantly for this thread: Vuichard would not have helped this pilot one bit.

[Gordy]

Thing is though, Robby pilots are generally only shown VRS recovery from an OGE hover,

I thought this practice ended in the late 90's. I have NEVER taught VRS from a hover. I always do a traffic pattern with a simulated floor of 1500' and on final tell the pilot to just pull the nose up to a decell and hold it, nothing else.

[Robbiee]

I thought this practice ended in the late 90's. I have NEVER taught VRS from a hover. I always do a traffic pattern with a simulated floor of 1500' and on final tell the pilot to just pull the nose up to a decell and hold it, nothing else.

Never heard of this way.

I got my PPL in 2003, and CPL in 2006, and throughout my training, insurance/rental checks, subsequent BFRs and six trips to the Robby Course, these past twenty some odd years, its always been done from a HOGE at around 2,000'.

Wouldn't mind trying your method though.

[SASless]

Gordy makes an interesting point.....as probably it is far more likely to encounter this horrid life threatening aerodynamic situation during a landing approach of some kind where the descending column of air catches up to the helicopter and begins to move forward of it.

At which point the floor falls out from under you and down you go.

It can happen while hovering OGE as well.

How many ways is there to encounter it....count them best you can.

How about hovering IGE on a pinnacle and drift too close to the down wind side....might that be a way?

Mustering.....might also provide some opportunities for it to kick off.

I taught it much like Gordy....but put the aircraft into a known downwind situation at 3,000 feet AGL and then asked the Student to do as Gordy described except I asked for the victim to achieve a OGE hover as best possible on the desired heading (down wind) and indicated altitude.

Nature, the laws of aerodyamics and gravity took care of the rest.

Sorry....but no undies got soiled doing these maneuvers as sometimes it was very tame and others not so tame but the concern was more of realizing the controls did not have their full normal authority although they were still working in normal sense but not as one is used to them doing.

One thing I did sense is that fully lowering the collective in a accelerating attitude (pitched down a bit) added stability to the rotor system.

In helicopter flying I am of the opinion there is more than one right answer sometimes and that is always contingent to the many different variations of conditions affecting the situation.

For instance, that is why in Test Flying....achieving the data points as set forth on the Test Card often take many repetitive attempts to get all of them accomplished in a satisfactory manner.

[jellycopter]

I’ve not seen the R44 crash video that many have discussed on this thread. However, I’m not so sure that many of the so called ‘Vortex Ring’ crash videos are actually Vortex Ring at all.

I was always taught that Vortex Ring was a combination of Root Stall on the inner portion of the disc and loss of lift on the outboard portion of the disc due to increased induced flow caused by the vortex. As Rate of Descent increases into fully developed Vortex Ring State, the stalled portion and the vortex section have expanded laterally, potentially to meet each other, rendering the rotor system ineffective at producing lift and hence control. Please feel free to correct me if I’ve got this wrong!

My reasoning is that if a Rotor disc, or more accurately a rotor blade, is experiencing Vortex Ring State, it is effectively no longer producing lift. If that’s the case, the coning angle would surely reduce? Most of the crash videos I’ve seen that are passed off as Vortex Ring State actually show an increase in coning angle, often just before impact. More a case of HTG (as a result of poor energy management and over-pitching) than VRS in my opinion.

I’d be interested to see the R44 video discussed earlier if anyone can point me to a link.

JJ

[Torquetalk]

JJ,

that video is very elusive! If Robbie has a copy it would be great to post it in the thread. I have also seen it whilst doing the Robinson factory safety course.

It really would be a good basis for this discussion on IVRS/VRS and Vichaurd. I can‘t see how it could be used without making the situation worse. A snake oil test perhaps?

[hargreaves99]

This has been discussed many times before, and yes, an awful lot of accidents that people/reports say are VRS are in fact overpitching, or simply the aircraft running out of power (too heavy, downwind etc)

[Robbiee]

I’ve not seen the R44 crash video that many have discussed on this thread. However, I’m not so sure that many of the so called ‘Vortex Ring’ crash videos are actually Vortex Ring at all.

I was always taught that Vortex Ring was a combination of Root Stall on the inner portion of the disc and loss of lift on the outboard portion of the disc due to increased induced flow caused by the vortex. As Rate of Descent increases into fully developed Vortex Ring State, the stalled portion and the vortex section have expanded laterally, potentially to meet each other, rendering the rotor system ineffective at producing lift and hence control. Please feel free to correct me if I’ve got this wrong!

My reasoning is that if a Rotor disc, or more accurately a rotor blade, is experiencing Vortex Ring State, it is effectively no longer producing lift. If that’s the case, the coning angle would surely reduce? Most of the crash videos I’ve seen that are passed off as Vortex Ring State actually show an increase in coning angle, often just before impact. More a case of HTG (as a result of poor energy management and over-pitching) than VRS in my opinion.

I’d be interested to see the R44 video discussed earlier if anyone can point me to a link.

JJ

Sadly, the only place I've ever seen that video is at the Robby Course (been there six times), and (even sadder) since they've doubled the price of that course I doubt I'll ever see it again,...unless you've got $1,500 bucks I can have, lol.

[[email protected]]

I’ve not seen the R44 crash video that many have discussed on this thread. However, I’m not so sure that many of the so called ‘Vortex Ring’ crash videos are actually Vortex Ring at all.

I was always taught that Vortex Ring was a combination of Root Stall on the inner portion of the disc and loss of lift on the outboard portion of the disc due to increased induced flow caused by the vortex. As Rate of Descent increases into fully developed Vortex Ring State, the stalled portion and the vortex section have expanded laterally, potentially to meet each other, rendering the rotor system ineffective at producing lift and hence control. Please feel free to correct me if I’ve got this wrong!

My reasoning is that if a Rotor disc, or more accurately a rotor blade, is experiencing Vortex Ring State, it is effectively no longer producing lift. If that’s the case, the coning angle would surely reduce? Most of the crash videos I’ve seen that are passed off as Vortex Ring State actually show an increase in coning angle, often just before impact. More a case of HTG (as a result of poor energy management and over-pitching) than VRS in my opinion.

I’d be interested to see the R44 video discussed earlier if anyone can point me to a link.

JJ
Only the middle section is producing lift but you make a good point about the coning angle, I hadn't really considered it with regard to VRS.

I certainly agree about the cause of many accidents not being VRS - underpowered helicopters are far more likely to run out of puff trying to manoeuvre in and around HOGE and end up overpitching as a result.

Granted, the end game in each case is usually a broken helicopter.

[Gordy]

Gordy makes an interesting point.....as probably it is far more likely to encounter this horrid life threatening aerodynamic situation during a landing approach of some kind where the descending column of air catches up to the helicopter and begins to move forward of it.

At which point the floor falls out from under you and down you go.

It can happen while hovering OGE as well.

How many ways is there to encounter it....count them best you can.

How about hovering IGE on a pinnacle and drift too close to the down wind side....might that be a way?

Mustering.....might also provide some opportunities for it to kick off.

I taught it much like Gordy....but put the aircraft into a known downwind situation at 3,000 feet AGL and then asked the Student to do as Gordy described except I asked for the victim to achieve a OGE hover as best possible on the desired heading (down wind) and indicated altitude.

Nature, the laws of aerodyamics and gravity took care of the rest.

Sorry....but no undies got soiled doing these maneuvers as sometimes it was very tame and others not so tame but the concern was more of realizing the controls did not have their full normal authority although they were still working in normal sense but not as one is used to them doing.

Exactly, when doing buckets on a 100’ line into the dip sites on cloudy days, you are on the edge of it all the way in the latter portions of the approach. I need pilots to recognize the incipient nature and make a cyclic adjustment without losing more than 20’ of altitude. It can be done, we sit right on the edge in training and go in and out of the start of it multiple times on one training event.

[Lala Steady]

Exactly, when doing buckets on a 100’ line into the dip sites on cloudy days, you are on the edge of it all the way in the latter portions of the approach. I need pilots to recognize the incipient nature and make a cyclic adjustment without losing more than 20’ of altitude. It can be done, we sit right on the edge in training and go in and out of the start of it multiple times on one training event.
And I presume a sidestep manoeuvre isn't very practical with a 100' line and water bucket underslung.

[Agile]

In my humble opinion i dont think Claude has ever been in VRS ! Having been there once I can assure you adding power to step out made it worse not better !!!!
In my trainee opinion, adding power did not change anything! lever up, lever down, its like it was disconnected, absolutly no change on the rate of descent! which was already much faster than anything I had seen in autorotation.
what increasing power does though, I assume, is increase your torque and consequently tail rotor pitch, and therefore your lateral slip stream.
Even if you main rotor is stalled and cyclic controlability degraded, the tail rotor is perfectly fine to help you step out of the VRS. I thought that was the whole principle of the Vuishard recovery.

[[email protected]]

what increasing power does though, I assume, is increase your torque and consequently tail rotor pitch No, that is what applying pedal does.

Vuichard's technique relies on cross controlling to sideslip out of the vortex - you need cyclic and yaw inputs since a yaw input alone will just turn the nose.

[NorthEh]

"I am very concerned about the dramatic increase in helicopter accidents in Europe in recent weeks.
We must learn from this that unfortunately we cannot improve the skills of pilots and flight instructors through administrative processes in one way or another.
The current over-regulation in Europe ultimately leads to the opposite. We cannot improve the skills of pilots and in any way through thousands of pages of operations and training manuals, audits, quality systems and checks.
The solution to rapidly reducing these accidents can only be achieved through efficient, evidence-based training in modern simulators." - via Claude Vuichard on Facebook today.

Apparently simulators are the only hope at preventing accidents?

[SASless]

'without all that paperwork, regulations, inspections, etc....how does one think the Jobsworths at mulitiple levels of government can earn a living then retire with a nice pension?

[[email protected]]

Perhaps they could stop using low time, hours building instructors who are little better than the students themselves.

But that would mean paying more...........

[jellycopter]

Perhaps they could stop using low time, hours building instructors who are little better than the students themselves.

But that would mean paying more...........

Come on Crab, our esteemed Royalist of Navies have just graduated their first ‘Creamie’ QHI. It must be the only way to go, no?

[Torquetalk]

- via Claude Vuichard on Facebook today.

Apparently simulators are the only hope at preventing accidents?

“The solution to rapidly reducing these accidents can only be achieved through efficient, evidence-based training in modern simulators."


Not quite. That may be A solution. It certainly isn’t THE solution.

There is some great work on helicopter flight simulation in Northern Switzerland, which is a long way forward of old procedure trainers or pretty crappy FNPTs. Modern software such as X-Plane, the rapid development of VR and even “affordable” full motion devices to put steering hardware onto, does indeed mean that a significant portion of flight training will surely be done on such devices in the future. Perhaps Vichaurd is making the case for getting his technique embedded into the syllabus? That would fit his suggested revisions for avoiding all VRS events as per the website:

From the beginning, train only "Vuichard Recovery" during the first few hours of PPL until it becomes a reflex when feeling a low-G at low speed
Equip all helicopters with a string (woolometer) to have a clear, visible and correct flow indication
Equip all helicopters with an IVSI
Train downwind approaches with special emphasis on a max. rate of descend <300ft/min
Review the procedure during all check flights
All civil aviation authorities should amend the FTO’s training manuals
All helicopter manufacturers should publish safety notice
All simulator manufacturers should review simulator behavior in VRS
Forbid all backward CAT A procedures in the AFM/POH
Amend asap the FAR&CS 27 and 29: manufacturers should provide data showing the rate of descent to enter in VRS in function of weight, altitude and temperature
Never use the autopilot in Auto Hover mode outside of flat areas, if the reference is taken from the radar altimeter

The recommendation of forbidding backward CAT manouevres is a curiosity. Such manouevres are bread and butter for some kinds of ops and are invariably used during take-off. Hard to see the VRS risk whilst going upward.

Perhaps more concerning is that VRS is a beast that is hard to quantify and that begs the question of how reliably the behaviour of the helicopter can be simulated. Let’s hope that the tail won’t be wagging the dog when it comes to programming X-Plane and similar engines to accommodate the new gold-standard recovery method that Monsieur Vichaurd would like to promote.

[Hughes500]

I have said this before but here goes again. My only time in true VRS occurred at 2000 ft AGL. Student had done 6 very nice recoveries from IVRS. We had one last go. Down wind pulling 18MAP in a Hughes 300. Airspeed has gone below 30 kts, GPS ground speed about 8. IVSI showing 700 ft a min airspeed indicator now less than 20 knots. Ac has already gone through the Hughes rumble ( loss of translational lift ) . I ask the student to recover, to my surprise he pulls full collective, almost instantly the ac pitches about 75 degrees up, no movement on the cylic. I glance at the IVSI which now is rapidly going south of 1500 fpm. I apply full left pedal and full forward cylic, NOTHING happens apart from my ring piece puckering. In desperation I dump the collective and push full right pedal. Now then ac is pitched what feels like 90 degrees nose down with ASI rapidly accelerating towards VNE. At this point the ground is worryingly close, gingerly apply rear cylic and a load of collective to stop the disc overspeeding. Pull the ac out just above tree top height. Back to airfield to change underwear . This is why I think Claude has never experienced VRS. Now i do a bit of line work ( about 1500 hours so not that experienced compared to a lot ) only problem with stepping left or right is a load of shouting from the ground crew as one swings the load into them ! I have always found it better to push forward but always willing to learn.

[Robbiee]

Curious now,...does Vuichard distinguish between VRS and IVRS? I only ask because this distinction is something I've only come across here on pprune. I mean, its been a while since I opened the text, but I don't remember the Rotorcraft Flying Handbook making it either? :ooh:

[krobar]

IMO, the Vuichard technique has merits, but it is an advanced manuevre that would waste a student's time learning during a PPL course. They need to know the signs of onset of VRS and how to prevent it from occuring, and the basic recovery method.


It is similar to doing 0 airspeed, or reverse autorotations. Yes, it can be done, but really, most of the time it is instructors showing off their skills.

[212man]

I have said this before but here goes again. My only time in true VRS occurred at 2000 ft AGL. Student had done 6 very nice recoveries from IVRS. We had one last go. Down wind pulling 18MAP in a Hughes 300. Airspeed has gone below 30 kts, GPS ground speed about 8. IVSI showing 700 ft a min airspeed indicator now less than 20 knots. Ac has already gone through the Hughes rumble ( loss of translational lift ) . I ask the student to recover, to my surprise he pulls full collective, almost instantly the ac pitches about 75 degrees up, no movement on the cylic. I glance at the IVSI which now is rapidly going south of 1500 fpm. I apply full left pedal and full forward cylic, NOTHING happens apart from my ring piece puckering. In desperation I dump the collective and push full right pedal. Now then ac is pitched what feels like 90 degrees nose down with ASI rapidly accelerating towards VNE. At this point the ground is worryingly close, gingerly apply rear cylic and a load of collective to stop the disc overspeeding. Pull the ac out just above tree top height. Back to airfield to change underwear . This is why I think Claude has never experienced VRS. Now i do a bit of line work ( about 1500 hours so not that experienced compared to a lot ) only problem with stepping left or right is a load of shouting from the ground crew as one swings the load into them ! I have always found it better to push forward but always willing to learn.
Out of interest, why demonstrate it downwind at 2,000’? The rotor system doesn’t know it’s downwind

[hargreaves99]

Its easier to demonstrate IVRS when downwind as you have to lose ETL. If you try demonstrating it into a 20 kt headwind you have to be moving backwards over the ground at 20 kts, which feels a little odd, and in reality most PPL holders are going to get into IVRS at altitude when they are downwind (eg circling someones house slowly to take a photo)

[hargreaves99]

Exactly.

And given FI pay is stuck at 2007 levels....


Perhaps they could stop using low time, hours building instructors who are little better than the students themselves.

But that would mean paying more...........

[paco]

"The rotor system doesn’t know it’s downwind"

It does with dirty air coming from the tail

[212man]

"The rotor system doesn’t know it’s downwind"

It does with dirty air coming from the tail
at 2,000’?

[paco]

Why not? The rotor system doesn't know :)

[albatross]

I will probably get a lot of flak for this but this is a combination of 2 posts on the old discussion.

I am posting a couple of photos just to relieve the monotony.

I was doing a job which entailed a lot of climbing, descending and hovering at high altitudes AGL.
I discovered that it is possible to enter VRS from a steady hover.
It was a great surprise the first time.
Due to the job it happened a lot. So I got the chance to try various things out.
Maintaining a vertical descent pulling power just increased the rate of descent.
Controls got sloppy but the aircraft did not enter any unusual attitudes.
There were no torque or RPM fluctuations.
Recovery was simple, Initiate forward or sideways movement and exit the column of descending air.
The aircraft was very light during these operations just myself and sometimes 1 passenger and around half fuel.
It warned you it was going to enter VRS. You would be happily sitting there at about 80%Q. The VSI would flicker (not even to 100FPM down) Altimeter would hardly move. If you did nothing it would enter VRS shortly thereafter. Pull a bit of collective and it usually entered VRS immediately and fully.
It only happened in calm wind conditions.
As we were hovering, climbing or descending on a ‘Laser’ beam you were never moving more than 2 feet in the horizontal from ground level to as much as 7000 AGL. Usually we only climbed 2000-4000 ft.
If you lost the ‘Laser’ beam you had to descend to ground level in order to reacquire it so sometimes I remained in VRS to descend.
The aircraft was being observed using a 50x theodolite so the surveyors could see the aircraft depart downwards. They would have me in the crosshairs as I hovered and suddenly I would depart downwards. They thought it was very funny to watch.
Just for info the aircraft had a cowling just abut under the fwd seats. The cowling had a screen on the bottom. Inside the cowilng was a video camera focused on the screen and a small 3 inch square monitor was installed on the instrument panel. A 10 amp gyro stabilized ‘Laser’ was placed on the ground pointed vertically upwards. You hovered low over the ‘Laser’ and placed the aircraft over it until you saw the ‘laser’ dot on the screen. You then initiated a climb at about 6-800 FPM keeping the dot as close to the center of the screen as possible. If you rapid control movements failed in this and you lost the dot you had to return to ground level and start over again. It took a lot of practice to learn the technique usually about 5 -10 hours. Some guys caught on quickly, some never could. The customer paid fro the training. They also allowed you to go out and practice if you didn’t do a shot for a day or two as it was a skill that required constant practice. Totally an eye, hands, feet coordination thing…if you had to think about it the dot was gone.

Starting from 100 ASL to 8000 ASL Temps -20 to +25C. Terrain100 ASL to 1500-2000.
Well some folks are going to say that entering VRS in still air and zero rate of descent is impossible.
In discussion years later with a very experienced and well respected test pilot he was surprised to hear of it but thought that it was just amazing that the circumstance was created. The ‘Laser’ keeping the aircraft in a +- 24 inch hover for extended periods and the aircraft being tracked with a theodolite. The chance to operate in the conditions described and stay in VRS for up to 1-2 minutes try various things and observe results was a unique opportunity. He said that they had never even thought of doing it and it would have been a separate test programme during which it would have been difficult to achieve the test parameters.. I agreed totally with him. It was an interesting thing but not worth the candle to spend time to explore. In the end what would have been the benefit of it a except the “Been There Done That” T-shirt.
You always lost the ‘Laser’ dot when it happened so you had to descend back down to ground level so staying in VRS was quick way to get there. I found exiting at a +-45 degree from aircraft heading with a +- 10 degree nose down attitude to gain fwd speed seemed to work best. You could exit by entering autorotation but this involved a considerable height loss. Exiting fully developed VRS with power applied and fwd speed was the most easy but when you are looking at VS anywhere from -1500 to -2500 it is going to take TIME and ALTITUDE to return to straight and level flight. As I stated before aside from the sloppy controls the aircraft never entered any unusual attitude or did anything scary. It seemed happy in the state it was in, no RPM, Torque or heading changes.

https://cimg5.ibsrv.net/gimg/pprune.org-vbulletin/596x395/img_6664_1fc0cf7f39d1139750adb6b0c6a77da262012c2e.jpeg
DLY a nice 350D. The Helicopter was brought to the hover over the laser with the beam hitting the screen on the cowling.
https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/596x395/img_6665_20c74af5017f6b437082ab8b512a6c380ad6c532.jpeg
The dot is displayed on the small TV screen on the right,
https://cimg7.ibsrv.net/gimg/pprune.org-vbulletin/2000x1681/img_6745_bb0bbcd9e99e53b89e3846407c9944a2be496a57.jpeg
The 10 amp gyro stabilized laser in position. Now just keep the dot in the screen and climb vertically 4-5 thousand feet and come to a stable hover for the surveyors to take the shot. .

[[email protected]]

Come on Crab, our esteemed Royalist of Navies have just graduated their first ‘Creamie’ QHI. It must be the only way to go, no?

it was going to come one day Jelly - I'm horrified that it has but Military flying training has been messed up so badly by the dogma of contractorisation that it's not a huge surprise.

If you need more QHIs and the system is too slow to produce them (and you are bleeding experience as people jump ship) then the idea of a creamie becomes more attractive.

For those that don't know the term it comes from the FJ world where the best students on the course were 'creamed off' to become instructors without any operational experience. Much like low time PPLs hour building via the AFI route.

[megan]

albatross, interesting story, one question, what was the aim of the task, some sort of survey work?

[605carsten]

- via Claude Vuichard on Facebook today.

Apparently simulators are the only hope at preventing accidents?

well, its a proven thing in the fixed wing world, the chopper world is woefully behind in that area, but hopefully the advancements in VR tech on a full motion platform will change that. On the most important note, he is absolutely right that the amount of paperwork chasing is destroying any safety advancements they are working for. Its insane the amount of crap we need to deal with in the fixed wing world, yet we have operators just avoiding crashing by 6ft on an approach, departing from wrong intersections, going offroading and back on the runway etc etc.. Basically flying skills are trash these days, but damn everybody is being chased for doing a fuel check 4min late or asked to do additional paperwork instead on focusing on the flight at hand. So Vuichard is completely right in this case.

[Torquetalk]

605carsten,
the 6ft incident was down to a basic altimetry error. Quite a wake up to realise that for all the sophistication of GNSS, PBN and RNP, an ATC screw up and lack of crew awareness could nearly bring the house down.

Could a sim scenario train against this? You bet.

Basic flying skills still matter and show. The AFCS requires more skill, it isn’t a substitute. Both need to be trained and tested.

[albatross]

albatross, interesting story, one question, what was the aim of the task, some sort of survey work?
Yes basically you were a very tall stadia rod. Pre GPS.
For example if you were cutting a base line for a power line and the next turning point was miles away you set up the laser on the turning point and climbed until the surveyor could see you. You then hovered there until he “took the shot, later on we mounted reflectors on the cowling front and sides so he could get a laser range too. .
The surveyor now could direct the line cutters on the correct path.
In hilly terrain that could be 3000 feet or more. I think the highest shot I did was 7000+, at that height the laser “dot” filled just about the entire screen.
If the laser was set up in soft ground you had to tell people near it not to walk around as it could cause the tripod to move which caused the stabilization to kick in and the dot would move in the screen causing you to think the helicopter was moving and make a correction.
If you lost the dot you had to descend well away from the beam as you didn’t want to be looking down and accidentally look into a 10 amp laser beam.
You tried not to use pedal much and soon discovered that ( into Wind ) a little collective up moved you forward and down moved you back so you used that a bit. The whole thing was muscle memory and constant practice was required which the client paid for.
It was common to turn slowly as you climbed and discover when you had a chance to look around that you had turned 60 degrees or more.
You could encounter rapid changes in winds aloft as you climbed at +- 1000 fpm and be blown “off the spot”. So you would, on your next attempt, slow your rate of climb to transition more slowly coming through the area of change.
Coming down after the shot we would just lay it on its side and peg the VSI.
It was a fun job. Great crews to work with.

[RVDT]

I will probably get a lot of flak for this but this is a combination of 2 posts on the old discussion.

I am posting a couple of photos just to relieve the monotony.

I was doing a job which entailed a lot of climbing, descending and hovering at high altitudes AGL.
I discovered that it is possible to enter VRS from a steady hover.

You can do the same these days with any Airbus Helionix equipped aircraft automatically which will hold ~ +- 1 metre with good DGPS data.

It will also drop you straight into VRS if you engage GTC-H (Ground Trajectory Control - Hover) from forward flight with a low power setting as engaging GTC-H does not automatically engage a Vertical axis.
You need relatively calm conditions of course. Not an issue if you have taken the time to actually read the AFCS FOBN.

Ground Trajectory Command in Hover mode (GTC.H)



The Ground Trajectory Command in Hover (GTC.H) mode is designed assist the pilot in acquiring and maintaining hover.

– When engaged from forward flight, the mode will acquire zero ground speed.

– In hover, the GTC.H mode maintains zero ground speed and constant heading when the cyclic stick and pedals are released.

The GTC.H can significantly reduce the pilot workload to maintain an accurate hover position, especially if the visual references are poor.

The GTC.H mode does not manage the vertical axis. The pilot must manually control the height/altitude or add a vertical mode (e.g. ALT or CRHT) when operating in GTC.H mode.

When GTC.H is engaged at a low power setting, failure to manage the vertical axis could result in a vertical descent and possible entry into vortex ring conditions!

[mechpowi]

But if you do engage collective axis autopilot with GTC.H (or any other mode), the Helionix will keep the helicoper out of VRS-region regardless of how much rate of descend pilot asks for.

[[email protected]]

well, its a proven thing in the fixed wing world, the chopper world is woefully behind in that area, No, the problem is that helicopters are far more difficult to model than FW and although you can make a generic model, accurately reproducing a particular aircraft requires accurate data from a fully instrumented real aircraft and no-one is going to pay to explore VRS in an expensive helicopter.
​​​​​​​
VR is a great training tool for some things but it would suffer from the same issues - accurately reproducing handling qualities in hazardous scenarios.

[albatross]

You can do the same these days with any Airbus Helionix equipped aircraft automatically which will hold ~ +- 1 metre with good DGPS data.

It will also drop you straight into VRS if you engage GTC-H (Ground Trajectory Control - Hover) from forward flight with a low power setting as engaging GTC-H does not automatically engage a Vertical axis.
You need relatively calm conditions of course. Not an issue if you have taken the time to actually read the AFCS FOBN.

Well that would take all the fun out of it!
The system was pre GPS and it was all hand flown.

When I originally talked about it with reference to entering VRS from a stable hover in these specific circumstances, ( very stable hover, OGE, extended time in the hover, no wind, no turbulence or down draughts etc) more than a few folks violently disagreed and stated that you could not enter VRS from a stable hover in calm wind conditions. Since then I have seen some of these same folks state with some authority that you can

One thing I never encountered was any sort of violent aircraft movements, unusual attitudes, torque fluctuations or vibrations. Just sloppy controls and an exhilarating rate of descent which could be increased with an increase in power. I sometimes spent up to 2 minutes in this flight regime as I had to descend back to ground level to reacquire the laser dot again anyway. I would exit the VRS with a 45 degree exit with power applied…worked every time. You would feel a bump as you exited (much like flying through your wake when doing. a 360 steep turn ) . Fun daze.

.

[FloaterNorthWest]

It will also drop you straight into VRS if you engage GTC-H (Ground Trajectory Control - Hover) from forward flight with a low power setting as engaging GTC-H does not automatically engage a Vertical axis.
You need relatively calm conditions of course. Not an issue if you have taken the time to actually read the AFCS FOBN.

What about the collective being engaged as a protection at 60kts?

[605carsten]

No, the problem is that helicopters are far more difficult to model than FW and although you can make a generic model, accurately reproducing a particular aircraft requires accurate data from a fully instrumented real aircraft and no-one is going to pay to explore VRS in an expensive helicopter.

VR is a great training tool for some things but it would suffer from the same issues - accurately reproducing handling qualities in hazardous scenarios.

yes, I agree.. in the fixed wing sims its the exact same issue… the FM at the outer edges of the envelope are not always like in real life!
I dont know how many times I have sat in a Level-D sim thinking that the damn thing does not fly like the real thing. My point is that its better than nothing as its akin to not teaching spin recovery to PPL students except have a quick chat about it. Same here. VR and modern tech has its advantages in certain training exercises in the same way you have to teach upset recovery in a real airplane as being upside down in real life is more unsettling than in a sim, but again doing all this in a Citabria is a whole lot easier than a 737also, so somewhat limited use also.

[RVDT]

What about the collective being engaged as a protection at 60kts?

Info is direct from Airbus Flight Operations Briefing Notice (FOBN)12-22 applicable to Software Step 3 K10_15274G_123 and personal experience.
Vortex ring protection is only applicable with a vertical axis engaged which does not occur with selection of GTC-H from forward flight unless you add a vertical mode manually.