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Vuichard technique for settling with power?

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Vuichard technique for settling with power?

Old 12th Sep 2017, 10:46
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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
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Old 12th Sep 2017, 11:42
  #242 (permalink)  
 
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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!
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Old 12th Sep 2017, 12:04
  #243 (permalink)  
 
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Apples V Oranges

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.
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Old 12th Sep 2017, 12:32
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http://www.pprune.org/rotorheads/676...-settling.html

for starters
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Old 12th Sep 2017, 12:33
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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.....
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Old 12th Sep 2017, 12:46
  #246 (permalink)  
 
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'If it ain't broke, don't fix it!'

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!

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

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

Happy Landings!
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Old 12th Sep 2017, 13:40
  #247 (permalink)  
 
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Originally Posted by Vertical Freedom View Post
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
Please outline why "poling sideward" does not help as well as "poling forward".
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Old 12th Sep 2017, 13:47
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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.
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Old 12th Sep 2017, 14:01
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Originally Posted by Thomas coupling View Post
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?
(that might be the reason he advocates right roll + left pedal for left turners)
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Old 12th Sep 2017, 14:04
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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.
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Old 12th Sep 2017, 14:30
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Originally Posted by Thomas coupling View Post
...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.
(A comment from a VRS novice) Going off the comments of those who have been in a fully developed VRS the helicopter is bib-bobbing all over the place. So the idea of being uncomfortable with the direction of cyclic input may be moot. I'd imagine by the time the world stops tumbling and the sideways movement becomes the next item of pilot attention then the machine is out of VRS state and can be recovered to forward flight - likely already straightened up before the VRS-novice pilot starts to think about it.

Note - my only exposure to what were called VRS were during initial training where the instructor demonstrated it to me in a 300. It were such a pleasant experience compared to what is described here that in hindsite I'd say we wern't anywhere near a developed VRS. I have though whilst mustering had what i thought were some bumpy settling with power incidents. And the difference is...






.
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Old 12th Sep 2017, 14:40
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Originally Posted by Thomas coupling View Post
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.
Absolutely! I've never ever done these things.
My "(I)VRS training" was one single demonstration by the FI at 1500ft AGL were I faintly remember a ROD of maybe 800fpm when he got excited & pointed out some "shaking/trembling of the frame" however unnoticed by me and did the normal pitch low nose forward maneuver. Then it was my turn, I was urged to "recover from VRS" at an even lower ROD, got a thumbs up, noted it as piece of cake and carried on with the training.

I'm pretty sure that should I personnaly ever get into "true VRS" ((c)pprune) I'll dump the pitch and autorotate away.

TC you'll most probably win your inital bet,
but I think that one has to practice either FDVRS escape, neither is comfortable,
especially for low height situations the ones with pitch raised.
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Old 12th Sep 2017, 14:43
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Originally Posted by Flying Binghi View Post
Note - my only exposure to what were called VRS were during initial training where the instructor demonstrated it to me in a 300. It were such a pleasant experience compared to what is described here that in hindsite I'd say we wern't anywhere near a developed VRS.
.
Exactly the same here. One never gets introduced to PPRuNe VRS during training, it just doesn't happen. Or maybe our 300s are VRS proof
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Old 12th Sep 2017, 17:19
  #254 (permalink)  
 
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As both instructor and examiner I find it very depressing that lip service is paid to VRS by instructors from what people are saying here
Reely a 300 will start to vibrate through its controls as it loses translational lift. At about 600 ft a min < 20 kts the airframe will start to shudder. At this point you can add power and she will climb ! Leave it to about 800 ft a min ROD and the ac is telling you she doesn't want to fly by shaking the arse off you. At this point any of the techniques work including Mr V's but I can't say I have noticed any difference between the techniques, certainly not a recovery in 20 to 50 ft ( not sure my altimeter is accurate enough to determine that )
As has been said the most important lesson is being shown what flying situations you would get this !
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Old 12th Sep 2017, 17:52
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Originally Posted by Hughes500 View Post
Reely a 300 will start to vibrate through its controls as it loses translational lift.
Hmm. I'll try to notice that the next time I take her for a spin.
Originally Posted by Hughes500 View Post
At about 600 ft a min < 20 kts the airframe will start to shudder. At this point you can add power and she will climb !
Colud be that I've been there during instruction. Wasn't particularly impressive, though.
Originally Posted by Hughes500 View Post
Leave it to about 800 ft a min ROD and the ac is telling you she doesn't want to fly by shaking the arse off you.
Definitely never been there.
Maybe our ROD was lower or we still had some forward speed.
Anyhow, my recollection of "ROD 800 fpm" must be wrong then, nerver ever did we do anything that shaky.

The only thing that actually made me hold my breath was when the examiner, one our way home from the check flight announced that "we'll do an auto together". As I've no idea how that shoudl work, I obediently nodded and simply "felt" te controls. He ripped her back, I'd only see blue sky in any direction (hence we mut have been verticall on her tail) , and did a nice autorotation to a soso power recovery.
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Old 12th Sep 2017, 18:13
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CRAB

Crab, thanks for your pragmatic and entirely logical post. It makes a lot of sense that in order to kick off the VRS, there is a massive lowering of power OGE in the simulation, and even though power is applied liberally to achieve the sink rate we saw, the condition is still very artificial. What we are doing is nothing like any real approach profile, no matter how poorly executed.

Trouble with being a low hour pilot is that there's no shortcut to having 10000 hrs, so some of us do attend courses and read these forums in order to try to become better pilots. Posts like yours greatly help with understanding the issues, and come across as far more professional and constructive than many of the others here.

I will try to tidy up my videos of the VT demo, which were taken with an iPhone. As we have glass we get a 'scan' effect, and the ROD descent bug can only be seen when zoomed in.

I'll post a link when I've got it sorted.

In answer to another question, whilst I've only done the RHC safety course in a 66, VT demos were most definitely being done in 44s too. Don't know about the R22 tho.

FF
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Old 12th Sep 2017, 19:33
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Am I the only one here who is getting a little worried that lots of keen/brave aviators, equipped with a variety of experience and skill, are being tempted to go off and investigate the boundaries of the VRS flight envelope?

Please, before you do, remind yourself about how the pitot-static system works and what sort of flight regime it is designed to work in. Then ask yourself whether a 600'/minute indicated rate of descent at an indicated airspeed of 10kt is likely to anywhere near accurate. I suspect that is why you often see qualified test pilots flying aircraft with all sorts of probes sticking out of them?

Cheers TeeS
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Old 12th Sep 2017, 19:50
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Not sure if this will successfully upload photo. If not, link should be self explanatory...

It's the best I could do with the poor video for now. Zero airspeed, 40% torque and ROD (lower right bug on PFD).

I'll try to upload video later - doesn't show a great deal more other than the machine bucking around a fair bit. I take Crab's point that pulling takeoff power from developed VRS at 40% torque is not equivalent to a slow, steep downwind approach with big power pulled through loss of ETL. Illustrates a decent rate of descent though.

EDIT - ROD descent displayed is showing 2100fpm. In video rises to 2400 but couldn't capture a decent still

FF

Last edited by FlimsyFan; 12th Sep 2017 at 19:52. Reason: Elaboration
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Old 12th Sep 2017, 19:53
  #259 (permalink)  
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Wow, what a thread! To think I started it in all innocence...

I guess my big question is why you would EVER end up in fully developed VRS, other than for demonstration purposes. Same as a spin in fixed-wing.

I've had exactly one case of unintended IVRS (HOGE in an R44 close to gross). I was out of it in a heartbeat - unintended but not unexpected!. Seems to me that whenever you're HOGE you're spring-loaded for IVRS. It's hard to imagine a situation where you'd get IVRS and not recover LONG before it turns into the real thing (though I did see the post about the ham-handed student).

Sideways recovery would make a lot of sense if you were say nose-in to the scenery, like the tour pilots in Hawaii showing the waterfalls. But even that isn't Vuichard, just moving the disk out its own shadow in a different direction. If I understand correctly, a key part of Vuichard is pulling MORE power.

So to all you experienced heli pilots... why would ever be in developed VRS in the first place?
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Old 12th Sep 2017, 20:01
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Flimsey

I assume the altimeter is on QNH in which case your instructor is not a wise man demonstrating VRS with less than 1500 ft underneath him.
In fact presumably not in VRS but IVRS
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