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Vuichard technique for settling with power?

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Vuichard technique for settling with power?

Old 23rd Mar 2015, 15:54
  #101 (permalink)  
 
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Originally Posted by n5296s
Just using right cyclic to slide out of the VRS, no pedal. We tried it, it certainly works (for incipient VRS, not the fully developed beast) - whether it works faster/better than forward cyclic is hard to say.
Between the point you make there, and the post by dammyneckhurts, the takeaway is "catch it early and recover" to avoid it getting worse ... regardless of your recovery technique.
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Old 24th Jun 2015, 01:50
  #102 (permalink)  
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Recently flew with a utility guy who also instructs. discussing VRS, he argued that most pilots will encounter it at low altitude, so conventional rcovery is problematic. Utility is frequently in that low/slow/high power, so often tried alternates. His point was get out of the VRS losing as little altitude as possible, lateral cyclic, that's it.
On my expressing doubt, we did a full VRS, conventional recovery, lots of altitude lost, perhaps a couple thousand feet.
Repeat maneuver, VRS, right cyclic and almost immediate recovery. Jaw drop. I can't say that the VRS was as fully developed the second time...
Explanation offered was that maneuvering laterally adds airspeed, but unlike reducing power and nosing down, the lateral move gets you into a normal airflow with minimal altitude loss.
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Old 24th Jun 2015, 06:32
  #103 (permalink)  
 
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Same here. Just tried it last month for the first time and it works
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Old 24th Jun 2015, 07:43
  #104 (permalink)  
 
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Angry

Why not just pole forward?
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Old 25th Jun 2015, 01:13
  #105 (permalink)  
 
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I do....
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Old 21st Oct 2015, 08:20
  #106 (permalink)  
 
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Rotor & Wing Magazine :: Flying Through the Vortex
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Old 21st Oct 2015, 08:50
  #107 (permalink)  
 
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Still yet to be convinced that this technique works in fully developed VRS any better than the conventional recovery.

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

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

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

As ever - avoidance of VRS is the real skill of a helicopter pilot, not the recovery from it.
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Old 21st Oct 2015, 10:02
  #108 (permalink)  
 
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suggestion (for side cyclic instead fwd.): rotational inertia

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

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

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

Last edited by Reely340; 21st Oct 2015 at 11:18.
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Old 21st Oct 2015, 12:41
  #109 (permalink)  
 
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How effective is this technique in an ac with a fenestron TR?

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

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

Matthew
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Old 21st Oct 2015, 12:51
  #110 (permalink)  
 
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Reely - that might be an issue in a rotor system with limited control power - eg teetering head (or close to) on R22 but anything with even a slight hinge offset will have control power to spare.

Also, any helo with a horizontal stabiliser will have natural nose-down pitch in a low speed descent.
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Old 21st Oct 2015, 13:20
  #111 (permalink)  
 
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Originally Posted by Reely340
suggestion (for side cyclic instead fwd.): rotational inertia

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

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

Thus if we want to redirect rotor downwash away from our VRS descend path
rolling the ac might work much faster than pitching.
That's a good point, but there is also the inertia of the entire mass of the aircraft with its load moving in the direction of intended flight. The lift vector (when changed in the direction of lateral movement) has to overcome that ... and is doing so (if one is actually entering VRS or in it) with a less effective "bite" into the air. As I've not flown Robinsons, no further ideas.
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Old 21st Oct 2015, 17:11
  #112 (permalink)  
 
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My first FI, a veteran of 2 wars, would frequently tell me that while training for emergency procedures were necessary, the fundamental approach was not to get the helicopter into a situation that led to you needing to implement those procedures. Obviously he was referring to thing like VRS, SWP etc but his advice has stuck with me.
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Old 15th Nov 2015, 02:17
  #113 (permalink)  
 
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Vuichard Recovery?

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

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

Aviation Today

Thanks!

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

Last edited by Chucklehead; 15th Nov 2015 at 04:33. Reason: Didn't search
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Old 15th Nov 2015, 02:18
  #114 (permalink)  
 
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See here:

http://www.pprune.org/rotorheads/557...ing-power.html
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Old 15th Nov 2015, 02:33
  #115 (permalink)  
 
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Angry VR

You need (again) air speed, so then; why pole Left or Right to recover to only again need to pole forward to regain critical speed? 'if it ain't broke, don't fix it" The old basics of pole forward for air-speed whilst leaving power ON, is the fastest & most effective recovery from VR & regain a Safe Flight configuration
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Old 15th Nov 2015, 03:42
  #116 (permalink)  
 
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You can't always "pole forward"...approach to elevated pad etc. Always nice to have another trick in the bag. I was taught this by Bristow back in '07, to avoid smashing into a deck offshore should you get into vortex ring state on short final. So it's hardly a new trick at all.

Last edited by TIMTS; 15th Nov 2015 at 03:58.
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Old 15th Nov 2015, 04:30
  #117 (permalink)  
 
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Lightbulb

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

Happy Landings
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Old 15th Nov 2015, 18:00
  #118 (permalink)  
 
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@VR
You need (again) air speed
That is not correct (assuming you have HOGE power). All you need is to get into undisturbed air which doesn't exert a downward force on you through recirculation.
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Old 15th Nov 2015, 23:37
  #119 (permalink)  
 
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Unhappy

Hey jyml; so the Vuichard stops the VR, great news & now You have now airspeed & a high rate of descent & then.......the circle begins again; VR due high rate of descent, no airspeed & power on hmmmmmmm
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Old 18th Nov 2015, 21:27
  #120 (permalink)  
 
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Seems as if you have a misconception of the procedure somehow. The rate of descent is quickly stopped to zero, so you cannot get into another vortex.

This might also help:
Rotor & Wing Magazine :: Flying Through the Vortex
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