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Vuichard technique for settling with power?

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Vuichard technique for settling with power?

Old 12th Mar 2015, 08:39
  #21 (permalink)  
 
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You are correct Crab....actually I should have said "high gross weight is not a factor" Thanks for clarifying that...
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Old 12th Mar 2015, 09:13
  #22 (permalink)  

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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?

(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?).

Sorry, Nigel
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Old 12th Mar 2015, 14:13
  #23 (permalink)  
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Settling with power term in the US

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.
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Old 12th Mar 2015, 14:57
  #24 (permalink)  

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I was taught to recognise that as over pitching, not VRS!
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Old 12th Mar 2015, 17:37
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It's not overpitching until the Nr decays
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Old 12th Mar 2015, 21:20
  #26 (permalink)  

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Oh, but it will....
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Old 12th Mar 2015, 23:02
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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/116...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............

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

Last edited by Thomas coupling; 12th Mar 2015 at 23:15.
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Old 12th Mar 2015, 23:31
  #28 (permalink)  
 
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Well done TC
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Old 13th Mar 2015, 01:21
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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)
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Old 13th Mar 2015, 06:36
  #30 (permalink)  
 
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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?
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Old 13th Mar 2015, 07:57
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hearing you TC, ......and it is almost time for the LTE v LTA to start up again...

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Old 13th Mar 2015, 08:26
  #32 (permalink)  
 
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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.
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Old 13th Mar 2015, 08:28
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ShyT
There's a smart one in every family! Definitely a grey hair moment, now fixed!!

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.

Last edited by Nigel Osborn; 13th Mar 2015 at 08:39.
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Old 13th Mar 2015, 08:38
  #34 (permalink)  
 
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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????
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Old 13th Mar 2015, 10:00
  #35 (permalink)  
 
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Originally Posted by AnFI
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.
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Old 13th Mar 2015, 12:55
  #36 (permalink)  
 
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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
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Old 13th Mar 2015, 14:03
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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.
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Old 13th Mar 2015, 14:14
  #38 (permalink)  
 
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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.
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Old 13th Mar 2015, 14:26
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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 !!

Last edited by Hughes500; 13th Mar 2015 at 17:02.
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Old 13th Mar 2015, 14:35
  #40 (permalink)  
 
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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.
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