Can Settling with Power Become Unrecoverable?

[Spike]

I know the title of this thread is a little misleading as settling with power is a "close to the ground" type of concern, but I'm curious as if it can become a dangerous situation when practiced at altitude.

 

A friend of mine told me they were practicing settling with power recoveries, and the instructor wanted to show him what "really getting into it is like". This meant that on the onset of the initial altitude drop and shaking, rather than recovering they aggressively pulled collective and really made it fall. He told me it made him pretty uncomfortable afterwords as the helicopter approached (or exceeded) a descent of 2,000 fpm, and was buffeting and yawing somewhat uncontrollably. Apparently this was held for quite some time and was described to me as "falling out of the sky".

 

I can't find any real good examples on youtube or any discussions of aggressive demonstrations, as the procedure is usually always to immediately recover.

 

Is this akin to spin training in fixed wing? Or is this something that was potentially very hazardous, and dare I say unrecoverable at a certain point.

 

VFlyer,

 

If you want to experience the full blown maneuver, simply go to a flight school with an experienced instructor who will teach it to you. Steer clear of the “kinder-gentler” schools who only teach it to the onset recognition stage as this really teaches you nothing significant. If you do, please come back and let people know it’s not a big deal and in fact, for some, it’s just another maneuver. With that, you’ll be speaking from experience and not hearsay…..

 

[Hand_Grenade_Pilot]

 

VFlyer,

 

If you want to experience the full blown maneuver, simply go to a flight school with an experienced instructor who will teach it to you. Steer clear of the “kinder-gentler” schools who only teach it to the onset recognition stage as this really teaches you nothing significant. If you do, please come back and let people know it’s not a big deal and in fact, for some, it’s just another maneuver. With that, you’ll be speaking from experience and not hearsay…..

 

 

The 'onset recognition stage' is by far the most important part...

 

What's the point of conditioning a pilot to be comfortable free-falling at 2500FPM if they can't quickly recognize the early warning signs and recover before the s*** really hits the fan?

 

Keep in mind that although the maneuver is practiced at altitude, you are simulating a recovery that would be done at a low altitude (If it accidentally develops outside of practice). If a pilot gets into fully developed VRS while landing, there isn't enough altitude to recover.

 

IMO, the idea is to condition the student to feel and see the warning signs early, and quickly recover before a significant loss of altitude occurs. Emphasis should be put on minimal loss of altitude during the maneuver. Because, if it starts to develop during landing, one only has a minimal amount of time/altitude to recover...

[Goldy]

So, who wants to go up to 10,000 feet in their little R22, initiate settling with power, then just sit there and see if a descent rate developes that's high enough that they cannot recover?

Pretty sure his name is Doug Tomkins......

[Rupert]

The Feds and the flight schools like to think they demonstrate settling with power, but in fact, they don't. You do not want to see settling with power, and it disturbs me that check airmen make me put myself and an aircraft at risk every year playing their pretend game.

 

When you experience real settling with power, all the pencils and chewing gum wrappers you haven't seen for years come floating up in front of your face. Zero g's. No vibrations, shuddering or shaking about it. Just immediate full acceleration of gravity, 32 f/s/s.

 

By the time you figure it out, the aircraft will have probably flown out of it by itself. Or, you will hit hard enough to destroy the airframe and collapsed a few vertebrae.

 

Next time some pretender wants to demonstrate settling with power, or wants you to demonstrate it, go up to 4000' or higher and let the helicopter flutter and vibrate a little for them so you can pass the checkride, but don't think for an instant that you have seen anything resembling settling with power.

 

You EMS guy watch out for downwind legs at night with a stiff tailwind. That'll do it.

 

Long line pilots sometimes see it bringing a hook in at a steep angle with light and variable winds. Light and variable will bite you in the butt.

 

Keep your rate of descent less than 300 fps and keep one foot in translational lift and the other out, and you'll avoid settling with power.

 

By the way, it doesn't happen in ground effect; and, in fact, can't happen in ground effect.

[rotormandan]

By the way, it doesn't happen in ground effect; and, in fact, can't happen in ground effect.

 

 

True statement. One time in a 206B3 I was at the end of approach (about 30' up just in the etl rattle) to a dirt parking lot when the old guy next to me( my mentor ), told me to go park by the apple bins over there. Over there was to the right and behind me. The apple bins were stacked up about 4-6 bins high with 2 rows coming together to shape an L. Without thinking about it I turned towards the bins as I was still decending that last bit of my approach. The winds were light but enough that I was downwind and lost etl. Plus with the wind bouncing off the bins we got into swp prettly quick. I was just below the tops of the bins and the 206 shook for a second and we just dropped. I recognized that it was swp but we were so close to the ground and with bins around me there wasn't anywhere to go to get a/s but behind me but not enough time for that. I just held on tight to the controls not moving the collectve and expected to land flat on the skids. At about 5-10' we just stoppd decending and settled into a hover.

 

We got lucky. I was close enough to the ground when we got swp that ground effect actually stopped us.

 

The old guy was transitioning me into the 206 ( 1st turbine ) that season and it was one if the 1st times he didn't put the duals in. I didn't live that one down for awhile.

[Spike]

 

The 'onset recognition stage' is by far the most important part...

 

What's the point of conditioning a pilot to be comfortable free-falling at 2500FPM if they can't quickly recognize the early warning signs and recover before the s*** really hits the fan?

 

Keep in mind that although the maneuver is practiced at altitude, you are simulating a recovery that would be done at a low altitude (If it accidentally develops outside of practice). If a pilot gets into fully developed VRS while landing, there isn't enough altitude to recover.

 

IMO, the idea is to condition the student to feel and see the warning signs early, and quickly recover before a significant loss of altitude occurs. Emphasis should be put on minimal loss of altitude during the maneuver. Because, if it starts to develop during landing, one only has a minimal amount of time/altitude to recover...

 

First of all, you have your opinion based on your experience while I have my opinion based on my experience….

 

 

When conducting part 141 stage checks and pre-check-ride applicant evals, I saw numerous students who, in their minds, recovered from the “onset” without even experiencing any symptoms of the condition. They simply reacted with rote inputs because of the fear instructors imparted upon them.

 

 

Mind you, I’m not saying recognition is not important. I am saying, from my experience, pilots should experience what happens if they fail to recognize the situation. Simply put, the first time shouldn’t be the last…… Moreover, if Robinson CFI’s do it with their students, why can’t you?

 

Edited July 27, 2013 by Spike

[Wally]

If you have altitude and don't do anything really stupid in the recovery, it's uncomfortable but not unrecoverable. Nobody likes the feeling of sloppy controls and a wallowy helicopter at several thousand feet, knowing that it's about to get weird as you take the express elevator down wiith lots of power only making it worse...

 

There's nothing like experience to leave a mark on your technique, fully developed settling with power will leave a permanent tender spot in a pilot's psyche. I think it should be demonstrated at sufficient altitude so that the student gets the disoriented feeling that comes with pulling collective and seeing the rate of descent increase.

Yes, it's hard to induce at altitude. I think that increases the inclination to minimize the assumed risk in daily flying- it can't happen to me by accident, I almost couldn't do it on purpose...

[iChris]

 

Keep your rate of descent less than 300 fps and keep one foot in translational lift and the other out, and you'll avoid settling with power.

 

By the way, it doesn't happen in ground effect; and, in fact, can't happen in ground effect.

 

 

By the way, it doesn't happen in ground effect; and, in fact, can't happen in ground effect.

 

 

This is why it’s important to know the difference between power settling (settling with power) and Vortex Ring State (VRS).

 

Those statements are true for VRS; however, they doesn’t always apply to Power Settling, as the term is used.

 

Remember, power settling (settling with power) is a symptom or effect. Vortex Ring State (VRS) is a cause that products a symptom or effect.

 

The cause of the so-called power settling (settling with power) is not always VRS.

Edited July 27, 2013 by iChris

[lelebebbel]

To add to Chris and Wallys posts, I believe that the way SWP and VRS is taught by most instructors is thoroughly confusing and not practical for the students.

 

As Wally said, it is quite difficult to induce actual VRS in most helicopters because the downwash velocity is too high, especially when the helicopter is heavy. So we are talking about a condition that is more likely to happen when the helicopter is lightly loaded.

 

SWP on the other hand is more likely to happen when the helicopter is heavy, and doesn't actually require any prior rate of descent.

 

SWP is common in many accident sequences, VRS is not.

 

The typical VRS demonstration at 3,000ft is an interesting experience that has its place. Instructors just need to stop pretending that that is what it's going to be like if you drop into a LZ too quickly, because it isn't. And the recovery from VRS at 3,000ft is a completely different ballgame than having to fly out of a SWP situation at 50 feet on an approach into a confined area (even though the control inputs may be the same). The latter is what the training should be focusing on.

Edited July 28, 2013 by lelebebbel

[Gomer Pylot]

IMO, the important thing, and the only important thing, is to recognize the onset of VRS, or SWP, and get out of it immediately. You will not get into it at altitude, you only get it at very low altitude above the ground on an approach. It can't happen in cruise, or at any appreciable airspeed. It happens close to the ground with low or no airspeed, and you have very little time to correct for it. Going to altitude and demonstrating full VRS is fine, for one demonstration, but what the pilot must do is recognize the very early stages and correct for it, just like correcting for engine failure. The allowable time for correction is close to the same.

[pilot#476398]

I looked up "settlng with power" in the glossery of the Helicopter Flying Handbook and it said, "see Vortex Ring State", so;

 

Vortex Ring State - A transient condition of downward flight (descending through air after just previously being accelerated downward by the rotor) during which an appreciable portion of the main rotor system is being forced to operate at angles of attack above maximum. Blade stall starts near the hub and progresses outward as the rate of descent increases.

 

Now if that last bit is correct, then it would seem that at some point when the ROD becomes high enough, the entire rotor will stall,...which would definitely be unrecoverable!

 

That's my guess anyway?

[LifeApresMil]

By the way, it doesn't happen in ground effect; and, in fact, can't happen in ground effect.

 

By the way, it doesn't happen in ground effect; and, in fact, can't happen in ground effect.


True statement. One time in a 206B3 I was at the end of approach (about 30' up just in the etl rattle) to a dirt parking lot when the old guy next to me( my mentor ), told me to go park by the apple bins over there. Over there was to the right and behind me. The apple bins were stacked up about 4-6 bins high with 2 rows coming together to shape an L. Without thinking about it I turned towards the bins as I was still decending that last bit of my approach. The winds were light but enough that I was downwind and lost etl. Plus with the wind bouncing off the bins we got into swp prettly quick. I was just below the tops of the bins and the 206 shook for a second and we just dropped. I recognized that it was swp but we were so close to the ground and with bins around me there wasn't anywhere to go to get a/s but behind me but not enough time for that. I just held on tight to the controls not moving the collectve and expected to land flat on the skids. At about 5-10' we just stoppd decending and settled into a hover.

We got lucky. I was close enough to the ground when we got swp that ground effect actually stopped us.

The old guy was transitioning me into the 206 ( 1st turbine ) that season and it was one if the 1st times he didn't put the duals in. I didn't live that one down for awhile.

 

I read this entire post and rotormandan had the MOST VALUABLE input of all, REAL experience. I'm glad for you that ground effect saved you dude. Those apple bins in your way, HOLY S**T!!!. What saved you was a proper ROD to allow ground effect to stop you. I've done the same thing several times, but always had room to ride it out into ground effect, but its scary holding still on the controls getting flat level like a parachute until your ROD goes to zero.

I remember teaching students to take off very slowly and smoothly using no collective inputs to sim max loads. I was frustrated with this one student so I snatched the controls and did an immediate turn around toward our starting point at about maybe 50 feet up. BAM, SWP, heavy with near full fuel load and a tailwind, I felt immediate settling. At that altitude, you tend to freeze, level the ship to slow your ROD as best you can and look for the best place to crash. Then you realize that maybe Ground Effect will save you and just try try try to ride it out with some ETL into as flat a descent as you can to allow for a sliding skid to a flat area that would allow for it. When ground effect takes hold, you breath a big sigh of relief and chalk that up as REAL experience.

I looked at that student and told him to share that with anyone that will listen. His next takeoffs were better. And I never did turnarounds like that again ever. Always give yourself an escape route or go in with slow ROD.

 

My VRS training was mostly same as everyone else's, getting into VRS in a big ROD, bucking kind of way. I was mindful of a tail slap. So later when I demo'd and taught it... rather than a cyclic input (which is way too easy), I'd have the student recover using smooth down collective only while holding cyclic still to maintain level (let pitch follow collective) and straight with pedals (to keep that parachute {rotor} fully extended and away from any possibility of a tail slap). The nose follows collective right, so you'll spill forward. Keep it gentle so you do not go into a big dive though...demanding another recovery maneuver. Hope it helps. This reinforces that nose follows collective.

[iChris]

I looked up "settlng with power" in the glossery of the Helicopter Flying Handbook and it said, "see Vortex Ring State", so;

 

Vortex Ring State - A transient condition of downward flight (descending through air after just previously being accelerated downward by the rotor) during which an appreciable portion of the main rotor system is being forced to operate at angles of attack above maximum. Blade stall starts near the hub and progresses outward as the rate of descent increases.

 

Now if that last bit is correct, then it would seem that at some point when the ROD becomes high enough, the entire rotor will stall,...which would definitely be unrecoverable!

 

That's my guess anyway?

 

Most all advanced textbooks don’t go along with that stall statement since the rotor in VRS is still producing thrust; however, that thrust is being pumped into an unstable flow that results in thrust instability.

 

The VRS region starts when the rate of descent is at about one-quarter, peaks at three-quarter, and disappears around 1¼ times the hover-induced velocity. In other words, the VRS has a defined range. As the rate of descent passes 1¼ times the hover-induced velocity the upward flow predominates and the rotor enters the autorotative flow state. The autorotative flow state offers an option for recovery from the VRS, if altitude permits.

 

Note the Autorotative Boundary dashed line. When you make collective adjustments to control RPMs in autorotation you’re actually adjusting flow across that line between the Autorotative Flow State and the Windmill Brake Flow State.

 

Below you can see how the flow states lineup as you move from the VRS into autorotation:

 

Edited July 29, 2013 by iChris

[eagle5]

By the way, it doesn't happen in ground effect; and, in fact, can't happen in ground effect.

 

 

I read this entire post and rotormandan had the MOST VALUABLE input of all, REAL experience. I'm glad for you that ground effect saved you dude. Those apple bins in your way, HOLY S**T!!!. What saved you was a proper ROD to allow ground effect to stop you. I've done the same thing several times, but always had room to ride it out into ground effect, but its scary holding still on the controls getting flat level like a parachute until your ROD goes to zero.

I remember teaching students to take off very slowly and smoothly using no collective inputs to sim max loads. I was frustrated with this one student so I snatched the controls and did an immediate turn around toward our starting point at about maybe 50 feet up. BAM, SWP, heavy with near full fuel load and a tailwind, I felt immediate settling. At that altitude, you tend to freeze, level the ship to slow your ROD as best you can and look for the best place to crash. Then you realize that maybe Ground Effect will save you and just try try try to ride it out with some ETL into as flat a descent as you can to allow for a sliding skid to a flat area that would allow for it. When ground effect takes hold, you breath a big sigh of relief and chalk that up as REAL experience.

I looked at that student and told him to share that with anyone that will listen. His next takeoffs were better. And I never did turnarounds like that again ever. Always give yourself an escape route or go in with slow ROD.

 

My VRS training was mostly same as everyone else's, getting into VRS in a big ROD, bucking kind of way. I was mindful of a tail slap. So later when I demo'd and taught it... rather than a cyclic input (which is way too easy), I'd have the student recover using smooth down collective only while holding cyclic still to maintain level (let pitch follow collective) and straight with pedals (to keep that parachute {rotor} fully extended and away from any possibility of a tail slap). The nose follows collective right, so you'll spill forward. Keep it gentle so you do not go into a big dive though...demanding another recovery maneuver. Hope it helps. This reinforces that nose follows collective.

 

I'm not sure I get what happened to you two? You were OGE, but not far above IGE, and I'm guessing too heavy to HOGE so you were just above ETL. Then you turned into a tailwind, lost ETL, and started to sink, but didn't hit the ground because you reached IGE before developing a too high ROD?

[iChris]

By the way, it doesn't happen in ground effect; and, in fact, can't happen in ground effect.

 

 

By the way, it doesn't happen in ground effect; and, in fact, can't happen in ground effect.

 

 

 

By the way, it doesn't happen in ground effect; and, in fact, can't happen in ground effect.

 

 

This statement can be misleading. Your ability to hover in ground effect (HIGE) is finite. At some point due to altitude, gross weight, wind conditions, airspeed, or rate of descent, even ground effect may not allow for an arrestment of your descent.

 

Settling can simply mean entering into a flight condition where the required power is more than the available power. An example would be finding it impossible to hover at the top of a mountain that was no trouble getting to with forward speed. You could find yourself settling through ground effect, as you slow to land and fall along the backside of the power curve.

Edited July 29, 2013 by iChris

[pilot#476398]

 

Most all advanced textbooks don’t go along with that stall statement since the rotor in VRS is still producing thrust; however, that thrust is being pumped into an unstable flow that results in thrust instability.

 

 

Which textbooks might those be?

[Wally]

By the way, it doesn't happen in ground effect; and, in fact, can't happen in ground effect.

 

 

True statement. One time in a 206B3 I was at the end of approach (about 30' up just in the etl rattle) to a dirt parking lot when the old guy next to me( my mentor ), told me to go park by the apple bins over there. Over there was to the right and behind me. The apple bins were stacked up about 4-6 bins high with 2 rows coming together to shape an L. Without thinking about it I turned towards the bins as I was still decending that last bit of my approach. The winds were light but enough that I was downwind and lost etl. Plus with the wind bouncing off the bins we got into swp prettly quick. I was just below the tops of the bins and the 206 shook for a second and we just dropped. I recognized that it was swp but we were so close to the ground and with bins around me there wasn't anywhere to go to get a/s but behind me but not enough time for that. I just held on tight to the controls not moving the collectve and expected to land flat on the skids. At about 5-10' we just stoppd decending and settled into a hover.

 

We got lucky. I was close enough to the ground when we got swp that ground effect actually stopped us.

 

The old guy was transitioning me into the 206 ( 1st turbine ) that season and it was one if the 1st times he didn't put the duals in. I didn't live that one down for awhile.

 

One needs to consider vertical surfaces near your intended landing, brought home to me long ago and far away, hovering into and out of revetments with walls 4 or 5 feet high. The aircraft got a little weird and random as one approached the L-shaped revetments, they disrupted and restricted the outflow, and got really random when the revetments were under the disk. Parallel wall revetments were easier, except there was minimal clearance laterally as the aircraft darted and bucked. Rotorwash next to any significant vertical will change outflows as they are diverted, can be accelerated in the process, and very turbulent.

 

Ground effect prevents VRS from developing, and it won't always save your bacon in a SWP situation. Sometimes all you can do is crash survivably, and level isn't so bad if you're not coming down really fast.

[ridethisbike]

I'd like to pose another question regarding VRS. I don't buy it for one second, but information being passed around is that if you are in full blown VRS that you can't auto out of it. And I do mean lowering the collective all the way and rolling off throttle. Obvious it would be poor form to try and do this anyways, but the discussion is posed as if you were demonstrating VRS at altitude.

 

The reason being spread is that due to the nature of the airflow, RRPM would be impossible to control.

 

 

Personally, I don't buy it. Recovery from VRS is to lower collective and gain forward speed followed by a climb out.

 

First thing you do in an auto? Lower collective.

 

What do you guys think? Would it be possible to safely, and in a controlled manner, enter an autorotation to escape VRS? Would RRPM remain a controllable energy?

 

 

DISCLAIMER: By no means do I think this should be practiced or even taught as a viable way to get out of VRS when close to the ground. I pose this for discussion purposes only.

[eagle5]

What do you guys think? Would it be possible to safely, and in a controlled manner, enter an autorotation to escape VRS? Would RRPM remain a controllable energy?

 

 

Rotorcraft Flying Handbook, page 11-6, paragraph 9, line 9, "In a fully developed vortex ring state, the only recovery may be to enter autorotation to break up the vortex ring state."

[Gomer Pylot]

I'm not sure rolling off the throttle would be a good idea. You can be in autorotation with the throttle open. I would tend to just put the collective down and remain able to fly away after getting out of it.

[helonorth]

I'm not sure rolling off the throttle would be a good idea. You can be in autorotation with the throttle open. I would tend to just put the collective down and remain able to fly away after getting out of it.

I agree. No point in rolling off the throttle.

[iChris]

"Most all advanced textbooks don't go along with that stall statement since the rotor in VRS is still producing thrust; however, that thrust is being pumped into an unstable flow that results in thrust instability."

 

Which textbooks might those be?

It is tempting to blame this on blade stall since not only does the power go up, but the thrust goes down. There is, however, another explanation that does not depend on stall. Helicopter Aerodynamics Volume II, Chapter 53, R.W. Prouty

 

Also:

Cyclic & Collective, Chapter 19, Page 176, Shawn Coyle

Rotorcraft Aeromechanics, Chapter 4.2, Wayne Johnson

Principles of Helicopter Flight, Chapter 19, W.J. Wagtendonk

U.S. Army Fundamentals of Flight, Chapter 6, Pg 6-43, FM 1-203

 

The section of the blade producing effective rotor thrush in the VRS is the relatively central areas between the root and tip, which allow enough control power for the pilot to fly clear with forward cyclic.

Edited August 2, 2013 by iChris

[aeroscout]

Forward cyclic isn't exclusively necessary. Side or rear cyclic will produce the same type of recovery. The key is horizontally exiting your own column of air.

[ridethisbike]

I'm not sure rolling off the throttle would be a good idea. You can be in autorotation with the throttle open. I would tend to just put the collective down and remain able to fly away after getting out of it.

 

 

I agree. No point in rolling off the throttle.

 

 

True, and I agree, but the discussion being had around here is with rolling the throttle down. The debate is whether or not RRPM would be controllable.

 

 

 

eagle5: Thanks for that, I'll make sure to point to it next time the discussion comes up.

[Joe_P148]

 

Sounds like recovering from SWP that bad would only be possible if you were high up, like on a photo flight perhaps? Close to the ground on approach having to point the nose almost straight down I'm guessing would end in a very loud crunch! Still to allow SWP to develope that badly I would imagine that I'd either have to be asleep at the wheel, or flying with my girlfriend while she's,...well...!?

 

Anyway, sideways recovery? I thought the AS indicator didn't work going sideways, which beggs the question, how do you know when its ok to pull up on the collective? Also, are they teaching it at the RHC course, since I may be there in a few months?

 

I wouldn't push the nose straight down to recover from settling with power, you are trying to exit the column of distrubed air not follow it to the ground. If you think about setling w/ power as an invisible column of air the diameter of your rotor system, all you are trying to do is get out of it, any direction you can. Altitude helps because it gives you the ability to recover by gaining airspeed, the condition known as mushing is simmilar to settling. This is when you set into a low power setting dive and as you attempt to pull out of the dive you begin to settle, the same technique of nosing forward applies to that situation as you are just trying to get forward airflow over the rotor system.

 

More importantly avoiding high rates of descent close to the ground is the best way to not ever get into settling with power. If you have to shoot a slow controlled approach, make sure IT IS INTO THE WIND! you have an out or a recovery path, free of obstacles just in case you setle. If you don't have OGE power just stay above ETL and shoot it shallow until you get into IGE.