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Power settling?

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Power settling?

Old 21st Sep 2002, 21:54
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Question Power settling?

Could someone venture an authoritive definition of Power Settling? It seems that half the people I speak to consider Settling with Power and Power Settling to be one and the same and the other half seem to know they're different but then go on to give varying different definitions of Power Settling!

Thanks!

Irlandés
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Old 21st Sep 2002, 23:14
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Well, I'll put myself up to be shot down by saying that I reckon settling with power, power settling and vortex ring state are all the same thing.
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Old 22nd Sep 2002, 01:04
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Nick Lappos
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Usage varies as to terms, but the training manuals agree with Arm.

A class of instructors seem to teach that "settling with power" has something to do with power limitations, loss of rpm and settling short on approach, but they only help to confuse things.
 
Old 22nd Sep 2002, 08:14
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Question

In the "Principles of Helicopter Flight" by Walter Wagtendonk states that Settling with Power and Vortex Ring State are one in the same thing....No mention of Power Settling though!!
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Old 22nd Sep 2002, 11:10
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Irlandes, are they talking about recirculation when they say power settling? It can be as much of a gotcha as vortex ring if you are operating into small sites with fences and buildings around them (Northern Ireland forts for example). Someone once bounced a Wessex 5 feet back into the air in a lovely place called Forkhill when he flared to the high hover just above the fence and then ran out of power as we sank into the fort and recirculation help us plummet earthwards. Thank God for the Wessex undercarriage!!
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Old 22nd Sep 2002, 12:03
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Hi Crab,
yes, now that you mention it, recirculation was one of the explanations given for 'power settling' by one of the more authoritive sources I know. Someone else said that it was coming in to land without enough power but I think that's just called 'bad power management'!

Just to add fuel to the fire here is an excerpt from an article on VRS by Ken Armstrong that appeared in Issue #11 of Pacific Rotors...

"When More Power Seems Like Less - There is some disagreement in the rotary wing world about the terms settling with power and power settling with various pundits defining each differently. However for this treatise, I will use the generally accepted terms settling with power and vortex ring state to define the same condition. Power settling will be discussed separately as a separate installation."
But I never got to read that 'separate installation' so never found out exactly what power settling was!

Irlandés
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Old 22nd Sep 2002, 13:19
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The Canadian or should I say Transport Canada definition does not treat each the same.

Settling with power is a situation that develops when the power available is not enough to arrest your rate of decent.( i.e. take off at sea level and climb to altitude, attempt a landing at lets say 6000' asl, have not consulted the charts and you find yourself in a situation where the power available cannot arrest your rate of decent.)
You can also create the same situation by making a hot approach with a high rate of decent and find yourself behind the power curve by the time you meet mother earth.
How many of you guys have entered a confind area with a sling load and felt that sinking feeling.....settling with power once again. Lets face it if you were in VRS in that situation you would be a statistic.

VRS is created by decending (300-1500 fpm, type dependent) at low airspeed, (0-30 knots, type dependent) , with power applied. You end up decending through your own downwash thus creating the vortex ring.
Recovery technique is to lower the power and gain airspeed. You can also autorotate but I like the first option better.

Therefore, (in Canada) VRS and Settling with Power are not considered as equals.

Settling with Power should be called "Settling without Enough Power"

Cheers

Xnr

Last edited by Xnr; 22nd Sep 2002 at 14:07.
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Old 22nd Sep 2002, 14:49
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The terms 'vortex ring'(European) and 'settling with power'(US) are definitions for the same situation, i.e significant vertical descent (>500fpm) with power applied(>50%tq) at low airspeed(<30ktas).
Having taught in the US and UK I found i could use the term settling with power effectively when descibing how to recognise the early stages of the effect in order to not let it manifest into the full and irrecoverable condition. Incipient vortex ring state as a term falls a little short for me and I save that for the full monty.

Power settling once again is a US term that is sometimes used to descibe limited power operations, i.e that point during the approach when a max power limit is reached and technique takes over as the means to arrive safely.
It can be confusing and I dont tend to use it, after all limited power is precisely that, limited power.
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Old 22nd Sep 2002, 16:36
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The way to go XNR!
I do totally agree with you...hey guys, here in Canada we do treat settling with power and VSR as two different things because they are!
Settling with power is when you don't have any more power available to stop de descent of the helicopter(even if you are within de 300fpm and less than 30 kts).For this to happen you need a combination of the 3 H: Hot High and Heavy!
On the other hand, VRS , can happen anytime, you can be as light as a feather and at Sea Level....that if you descent at more than 300fpm and at less than 30Kts you are flying in your own downwash! As my instructor at Canadian Helicopters said VSR is as if you farted in your own sleeping bag!
Hope it helps!
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Old 22nd Sep 2002, 19:12
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It would appear that you guys in Canada use the term settling with power for limited power situations. My two Principle of flight bibles are quite clear about the two terms (swp & vrs) as the same.
What fundamentals of flight reference do you use which states the case differently?
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Old 22nd Sep 2002, 22:34
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So summing up this particular can of worms so far, here are the various different takes on the situation...

1. VRS is the same as Settling with Power. Power Settling is a Recirculation type situation.

2. VRS is the same as Settling with Power. Power Settling is 'Settling without enough power'.

3. VRS is not Settling with Power. Settling with Power is 'Settling without enough Power' (Xnr's suggested definition). So what is Power Settling according to this posture?

And when I originally posted I assumed that the VRS=SWP part was beyond dispute! Apparently not. That said, all the texts I've ever read have treated the two as one and the same. It was the Power Settling I was worried about! I suspect that because the two terms are so similar people have been using them interchangeably for years without suspecting that they could be in fact two different conditions. Then you end up with 'old dog, new tricks' syndrome. Just a possibility of course.

Anyway, all this has given me a headache. I'll find something easier to think about. Nuclear fission perhaps...

Irlandés
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Old 23rd Sep 2002, 00:07
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Arrow

XNR has the correct interpretation. Vortex ring is one thing, Settling with Power another.

Another description of settling with power would be the SA365C, with the fixed pitch limit on the collective, where a moderately hot approach could (and sometimes does) finish with plenty of engine power available, but unuseable because the collective has reached its physical limit. Strange bit of French design, which has caused a few heavy landings along the way. I'm sure that there would be other helicopters with a similar feature.
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Old 23rd Sep 2002, 01:22
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Is it necessary to go back down this well trodden road?
Do a search on PPRUNE for this subject, read Nick Lappos's site and you will have plenty to do for the next months.
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Old 23rd Sep 2002, 03:41
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Unfortunately, the ad hoc definition of "settling with power" as a purely power phenomina is not correct, in Canada or elsewhere. The idea that such a definition is needed for "an approach where insufficient power is available" is right on, but settling with power is not the term.

Check here:
http://www.dynamicflight.com/aerodyn...ettling_power/


XNR, do you have a reference to a publication of the Canadian usage of settling with power for a purely power problem?

Evidence of the confusion caused by misuse of the terms is shown by the confusion about recirculation, which is the cause of VRS/Power settling/settling with power. It is the recirculation of the downwash that causes all the misery of VRS.

We should actually agree on a term for the falling through on an approach that is caused by insufficient power, and stick to it.

Otherwise, we should declare this thread to be "Condition Alpha" and simply re-run it every 3 months, which is about how long it takes PPRUNE to forget the last time we all tossed this ball around!
 
Old 23rd Sep 2002, 10:37
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There is no way I can wait 3 months to toss my balls !!
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Old 23rd Sep 2002, 12:25
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Steve76,
I'm not naďve enough to think I'm the first person who has asked this question nor will I be the last and sorry about flogging a dead horse but when I went to do a search on power settling, I couldn't find the search button (ironic, isn't it?). I could have sworn it was on the top of the page. Anyway I subsequently found it after posting. Is it my imagination or did it get moved??

Good idea Nick about coining a phrase that everyone can agree on. I mean it can't be that hard to make all the world's helicopter pilots agree on something. Ha ha! For what it's worth, here's my suggestion: "Power Deficit Landing". Any takers?

Irlandés
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Old 23rd Sep 2002, 16:19
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settling

How about looking to Mr. Webster to help.

Settling:

v. intr.
To discontinue moving and come to rest in one place.
To move downward; sink or descend, especially gradually
"

When one uses the word settling in it's proper usage, one tends to think of settling with power as a power limitation problem. Taken to a bit of an extreme every landing we make is a form of "settling with power". Just because a word is used in a book does not make that word correct, if it isn't used properly.

Cheers

Randy_G

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Old 23rd Sep 2002, 17:20
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IMHO, landing hard due to insufficient engine power/Tq available carries the label "pilot error". I know you've either done it, or will in the future (and I have, no mistaking that), given the nature of the job, but it is as simple as that. Unfortunately..

But Hot Approach sort of sums it up and is nice and concise. Any takers?
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Old 23rd Sep 2002, 20:49
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S76 Heavy VRS is usually caused by "pilot error" too (and is 100% preventable too). As you say the label of pilot error is usually attached to any hard landing due to insufficient power. As we all know, an error may not have been made at all.

For instance; you are on short final, and have done every single kind of recon known to humans, you note where the prevailing wind is, and the surface wind, and then the wind can still change suddenly and become a downdraft causing a hard landing. I would be rather cautious to call that kind of scenario "pilot error". You only have to ask anyone who heli-skis, or just flies at something higher than sea-level, and a hard landing can be just a gust away.


Cheers

Randy_G

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Old 23rd Sep 2002, 21:35
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Randy G, been there, done that. After all the trouble I went through to check everything, I found that it wasn't enough. I was lucky in the sense that we stopped inches off the surface, saved by the ground effect.
If something breaks it will be labeled pilot error, that's my point.
I am NOT pointing fingers at anybody who has had the misfortune.
Perhaps me flying mostly at sea level with (usually) no power shortages will explain why I chose to express myself that way. But hey, better men than I have been caught.

But I was taught that "settling with power" =VRS. I understood that to mean that "even with application of lots of power, the A/C will settle towards terra firma". Therefore I hope that a less confusing description will be found soon.

So I hope no offense taken, as it was certainly not meant to offend.
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