When practicing vortex ring.........
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What stopped me from becoming an integral part of sovereign territory ?........Training ! Two parts to that. 1stly fixed wing stall training and recovery, (demonstrated and actual) and 2ndly rotary demonstration of incipient condition and hands on induction and recovery. Whilst all the "POF" is very interesting, even a generation on, much better and brighter heads than mine are still disputing the theory behind VR. From a practical point of view, trainers,..... do please keep this in the syllabus, It is a challenging exercise for all involved,............but from the box marked "Helicopters - things that will one day bite you on the bum", this has to be near the top of the pile
B rgds
BS
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BS
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Geoffersincornwall wrote:
DON'T DO IT.........
...........IN THE HELICOPTER.......
If you are going to rehearse the recovery from VR (Settling with Power if you prefer) then do it in a simulator. You can crash all day and still go home for supper.
DON'T DO IT.........
...........IN THE HELICOPTER.......
If you are going to rehearse the recovery from VR (Settling with Power if you prefer) then do it in a simulator. You can crash all day and still go home for supper.
Last edited by HueyLoach; 30th Jun 2012 at 23:02.
Unfortunately, your simulator needs to be setup with the right parameters for VRS pertinent to your aircraft. Ours seems to have the standard 30 kts and 500fpm so it puts you into VRS even when you are not even close.
Having said that, it does at least allow you to practise the recovery.
Having said that, it does at least allow you to practise the recovery.
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Dont Do It!
Totally agree with "Geoffersincornwall"! 
If you keep practicing the "Downwind" VRS at some point you will end up in a whole lot of trouble trying to recover! I was always taught "Into wind" VRS, then on my instructors test, i had to do the "Downwind" way,,,,i absolutely **** myself and recovered from 2300 ft start point,, at around 800 ft,,,
From that moment on,,,,i teach upwind,,,its enough to demonstrate the problem without putting the fear of god up the students! No doubt you'll get away with it for so long but keep at it and one day,,,,it'll bite you.
If you keep practicing the "Downwind" VRS at some point you will end up in a whole lot of trouble trying to recover! I was always taught "Into wind" VRS, then on my instructors test, i had to do the "Downwind" way,,,,i absolutely **** myself and recovered from 2300 ft start point,, at around 800 ft,,,
From that moment on,,,,i teach upwind,,,its enough to demonstrate the problem without putting the fear of god up the students! No doubt you'll get away with it for so long but keep at it and one day,,,,it'll bite you.
VRS done intentionally is not the bugbear it is being made out to be....or should not for a competent pilot. Can it be interesting in aircraft response....maybe...but then it is an intentional maneuver and one should be prepared for "unusual" reactions.
It is unintentional entry into VRS and particularly when close to the ground that VRS becomes the bugbear it is known to be.
One man's opinion developed over almost forty years driving these wonderful machines we call helicopters.
BLC says it right.....VRS Demo's are not ground reference maneuvers.....simply air work....unless you are doing something horribly wrong.
In reality....could one not do this all by reference to instruments? During my US Army Instrument training....we did so as a part of unusual attitude exercises but did not call it VRS by name. Instrument indications can be fun to figure out while all this is going on....but just as doing it by eye looking outside the windows....attitude, heading, airspeed, and power are the keys to recovery followed by rate of climb once forward airspeed is regained.
On instruments the key is knowing how you arrived at the situation you find yourself in.....so it is not really a complicated concept or exercise to conduct.
It is unintentional entry into VRS and particularly when close to the ground that VRS becomes the bugbear it is known to be.
One man's opinion developed over almost forty years driving these wonderful machines we call helicopters.
BLC says it right.....VRS Demo's are not ground reference maneuvers.....simply air work....unless you are doing something horribly wrong.
In reality....could one not do this all by reference to instruments? During my US Army Instrument training....we did so as a part of unusual attitude exercises but did not call it VRS by name. Instrument indications can be fun to figure out while all this is going on....but just as doing it by eye looking outside the windows....attitude, heading, airspeed, and power are the keys to recovery followed by rate of climb once forward airspeed is regained.
On instruments the key is knowing how you arrived at the situation you find yourself in.....so it is not really a complicated concept or exercise to conduct.
Avoid imitations
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Hueyloach,
After which, if not recovered by then, what are you supposed to do next?
If I remember correctly according to the FAA Rotorcraft handbook the minimum recovery altiitude is1500 ft.
It is also part of the JAR-FCL syllabus. The incipient stages, indications, and correct recovery are required to be taught.
1500ft (JAR-FCL 2000ft) is a minimum height at which incipient VRS and recovery are to be taught. And recovery action is to be taken immediately.
TT
1500ft (JAR-FCL 2000ft) is a minimum height at which incipient VRS and recovery are to be taught. And recovery action is to be taken immediately.
TT
No problem Shy.....one shall never go much below 0' AGL no matter how badly it turns out!
If one starts at 4,000 feet AGL....that gives you 2,500 feet before it becomes an issue. One would assume the entry altitude would vary by aircraft type....something like a Bell 47 would differ than say....an H-53E. The Demo is only to show Incipient VRS....not entry into full VRS.
What rules apply to such exercises in CAA/JAA/EASA or whatever-you-are calling-yourselves-this-week-land?
If one starts at 4,000 feet AGL....that gives you 2,500 feet before it becomes an issue. One would assume the entry altitude would vary by aircraft type....something like a Bell 47 would differ than say....an H-53E. The Demo is only to show Incipient VRS....not entry into full VRS.
What rules apply to such exercises in CAA/JAA/EASA or whatever-you-are calling-yourselves-this-week-land?
Last edited by SASless; 1st Jul 2012 at 15:12.
SAS
I think it's EASA this week, but no-one is really sure.
Not sure about rules as such, but the regulations for licensing specify what is to be taught. The how bit comes from where you get taught. Some of the bigger schools have practice notes for their FIs/CFIs(e.g. Bristow).
In the wider world, practice can vary a bit more. I have met CFIs/FIs who don't teach it for PPL (and likely at all), seeing it as an "advanced manouvre" as opposed to preventative and emergency training; some who just let the aircraft fly a little bit itto it's own vortices at height then recover without allowing the incipient element to begin; some who aggresively put the TTP way below the horizon in the belief that you get more airspeed more quickly that way; others who teach auto as the way to get out. On the whole, though: most seem to do more or less the same, allowing the incipient state to begin indicated by a sudden ROD acceleration, then put the disk at the horizon, maybe lower the lever a bit, wait for indicated airspeed then pull pitch again to recover.
The point about type is may be important. Most civi training is done on light piston aircraft. In an earlier discussion, it was said that the lighter the machine, the lower the ROD required to get into VRS due to the relative masses involved. Following this, the incipient indications will develop with less loss of height in lighter machines. And this probably extends to the required height to recover.
TT
I think it's EASA this week, but no-one is really sure.
Not sure about rules as such, but the regulations for licensing specify what is to be taught. The how bit comes from where you get taught. Some of the bigger schools have practice notes for their FIs/CFIs(e.g. Bristow).
In the wider world, practice can vary a bit more. I have met CFIs/FIs who don't teach it for PPL (and likely at all), seeing it as an "advanced manouvre" as opposed to preventative and emergency training; some who just let the aircraft fly a little bit itto it's own vortices at height then recover without allowing the incipient element to begin; some who aggresively put the TTP way below the horizon in the belief that you get more airspeed more quickly that way; others who teach auto as the way to get out. On the whole, though: most seem to do more or less the same, allowing the incipient state to begin indicated by a sudden ROD acceleration, then put the disk at the horizon, maybe lower the lever a bit, wait for indicated airspeed then pull pitch again to recover.
The point about type is may be important. Most civi training is done on light piston aircraft. In an earlier discussion, it was said that the lighter the machine, the lower the ROD required to get into VRS due to the relative masses involved. Following this, the incipient indications will develop with less loss of height in lighter machines. And this probably extends to the required height to recover.
TT
It's not weight specifically, it is disc loading that determines your downwash speed and hence the RoD required to encounter VRS.
As it happens the light pistons have relatively low powered engines and larger rotors so the disc loading is lower.
It seems that your downwash speed in the hover in feet per min is roughly equivalent to your RoD in autorotation so, once you know this you can avoid VRS by keeping RoD at slow speed to less than half of that figure.
As it happens the light pistons have relatively low powered engines and larger rotors so the disc loading is lower.
It seems that your downwash speed in the hover in feet per min is roughly equivalent to your RoD in autorotation so, once you know this you can avoid VRS by keeping RoD at slow speed to less than half of that figure.
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At this late point in this thread, may I interject?
The only way I could repeatedly get the symptoms for vortex ring state was, at a suitable height above ground, enter from a downwind deceleration. Determine the wind direction at altitude from cloud shadows, or pre-flight weather info.
Starting at 60 knots or so, use a power setting that is less than the power required to maintain level flight, but decelerate maintaining altitude. Passing through about 20 knots, the first symptoms of low frequency airframe vibrations (or buffeting) appears. As the speed passes less than 10 knots or so, the helicopter will start to settle, and the second symptom appears- uncommanded pitch, roll and yaw oscillations. (i.e. the ontrls aren't being moved and the helicopter is dancing around) The rate of descent at this stage should be 300-500 feet per minute. And the student should be told that this is the furthest point you should go before recovery, except here we may want to see what happens if power is applied to recover, instead of lowering the nose.
If the power is increased, the rate of descent may (and I must emphasize may) increase.
Recovery is made by positively lowering the nose to at least 20° nose down.
Typical height loss is less than 500 feet.
I have never been able to satisfactorily get the symptoms (the buffeting and uncommanded pitch, roll and yaw) when trying to do this entering from into wind.
And if you don't get the symptoms, the student isn't going to be aware of them for later life.
The only way I could repeatedly get the symptoms for vortex ring state was, at a suitable height above ground, enter from a downwind deceleration. Determine the wind direction at altitude from cloud shadows, or pre-flight weather info.
Starting at 60 knots or so, use a power setting that is less than the power required to maintain level flight, but decelerate maintaining altitude. Passing through about 20 knots, the first symptoms of low frequency airframe vibrations (or buffeting) appears. As the speed passes less than 10 knots or so, the helicopter will start to settle, and the second symptom appears- uncommanded pitch, roll and yaw oscillations. (i.e. the ontrls aren't being moved and the helicopter is dancing around) The rate of descent at this stage should be 300-500 feet per minute. And the student should be told that this is the furthest point you should go before recovery, except here we may want to see what happens if power is applied to recover, instead of lowering the nose.
If the power is increased, the rate of descent may (and I must emphasize may) increase.
Recovery is made by positively lowering the nose to at least 20° nose down.
Typical height loss is less than 500 feet.
I have never been able to satisfactorily get the symptoms (the buffeting and uncommanded pitch, roll and yaw) when trying to do this entering from into wind.
And if you don't get the symptoms, the student isn't going to be aware of them for later life.
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It will work better if you made your helicopter shadow follow the cloud shadows while being the same height AGL as the clouds. This will very closely approximate zero movement through the air which is what is needed. Forget about movement over the ground as it is irrelevant for this excessive. You can do this in any direction because zero is zero. To recover make the helicopter shadow move independently from the cloud shadow. Again any direction will do however forward feels much better.
Funny how many posters on here are convinced they know better than a very experienced test pilot and author of helicopter books
Avoid imitations
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Funny how many posters on here are convinced they know better.....
It seems that your downwash speed in the hover in feet per min is roughly equivalent to your RoD in autorotation so, once you know this you can avoid VRS by keeping RoD at slow speed to less than half of that figure.
Obviously bfcl is correct - zero airspeed is zero airspeed - makes no difference whether your ground speed is negative or positive at the time.
((except during the windsheer element perhaps at low level - where it counts and 'downwind' would be better ironically)).
VRS requires 2 elements:
Induced Flow (ie Powered flight)
and
An opposing airflow (ie combination of low airspeed (eg less than 3kts) and a RoD (eg more than 3 kts)
Fully developed VRS is elegant and the 'buffeting and random attitude changes' generally stop.
Also buffeting and uncommanded pitch, roll and yaw is a pretty poor warning indicator since although they most often do occur, you can just slip neatly into VRS without experiencing those first - if your really lucky.