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deuce bigalow

Vortex Ring State Versus Settling With Power.

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In over 30 yrs in the biz this is one topic that seems to generate a lot of confusion.

 

Lets hear some opinions?

 

for the record my opinion is:

 

VRS= decending in the machines own downwash. Lift becomes anti-lift. Three conditions are 1. a rate of decent more than 300 feet per minute. 2 airspeed less than effective translational life. 3. At least 20% power applied.

 

Settling with power is what happens when you head into a confined area without doing a power check and find out as you come over the trees that you are pulling 100% tq and still going down.

 

Now a lot of people use the terms settling with power and VRS interchangeably.

 

So thats what I think. I have donned my armour and am standing by for incoming. :P

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A little shy on the rates of descent.

 

would have to say at least 700 fpm when below translational lift.

 

If you have a large power margin, it is said that you cannot get into vortex ring even with a 3500 fpm descent.

 

an excellent thread on this on the pprune site, search for "vortex ring"

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Vortex ring state is an aerodynamic condition affecting the main rotor system. It can be encountered with almost any VSI reading and its formation is dependant on a number of conditions, gross weight, power applied, wind direction and strength... It is unlikely to occur at VSI readings which approach the autorotational decent rates of the particular machine you flying, as vortacies generated will be above the rotor system. This being said, it is still possible if partial power is applied and airspeed is reduced or at speeds around translation.

 

Settling with power was best described to me as being similar to driving your car at 100 km/hr toward an intersection with a red light. If you apply the brakes at the stop line you cannot expect the vehicle to stop in time. Same thing with the machine. Settling with power is not an aerodynamic condition of the rotor system rather it is a result of improper power management on the part of the pilot.

 

Settling can lead to vortex ring state if the condition is left long enough without proper recover technique applied.

 

The terms are not interchangeable. This is how it was explained to me. My $.02, nothing more.

 

HG-12

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Vortex ring state is an aerodynamic condition affecting the main rotor system. It can be encountered with almost any VSI reading and its formation is dependant on a number of conditions, gross weight, power applied, wind direction and strength... It is unlikely to occur at VSI readings which approach the autorotational decent rates of the particular machine you flying, as vortacies generated will be above the rotor system. This being said, it is still possible if partial power is applied and airspeed is reduced or at speeds around translation.

 

Settling with power was best described to me as being similar to driving your car at 100 km/hr toward an intersection with a red light. If you apply the brakes at the stop line you cannot expect the vehicle to stop in time. Same thing with the machine. Settling with power is not an aerodynamic condition of the rotor system rather it is a result of improper power management on the part of the pilot.

 

Settling can lead to vortex ring state if the condition is left long enough without proper recover technique applied.

 

The terms are not interchangeable. This is how it was explained to me. My $.02, nothing more.

 

HG-12

I'd have to agree with you 100% Rick.

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Vortex Ring State is an aerodynamic phenomenon. The inner portion of the main rotor blade do nothing to provide lift, instead, the air is flowing upwards. When the a/c is a slow moving condition under heavy weight and/or high power setting and/or zero wind, the tip vorticies will increase so much that the vortices meet up with the inner upflowing air and circulate as a donut and increases greatly until the a/c is unresponsive in flight control inputs. The pilot will recognize that "he was into wind if there was wind, he had power coming in as normal, and the rate of descent on approach was carefully monitored. You can call this VORTEX RING STATE.

 

As for Settling With Power, well, it's exactly what it is called. Settling With Power is completely PILOT INDUCED! Your first warning is the a/c will start to feel slightly slow to respond, immediatly to follow will be the 'shuddering', then the controls will feel lagging and/or sloppy. and of coarse the sinking increasing rate of descent, not getting better by you adding collective.

You caused this because of not being into wind and/or, high rate of descent and/or low airspeed w/ low power setting. These are totally PILOT controlled characteristics.

 

You can not call them the same. Or can can You Meant to mean that. They are different.

 

To correct either one, it is the same recovery technique. Lower collective if altitude permits, move a/c to the side or forward, to get airspeed, or clean air.

 

Anyone disagrees, please feel free to correct me.

 

Ceez.

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Guest Angry Egg Driver
Vortex Ring State is an aerodynamic phenomenon. The inner portion of the main rotor blade do nothing to provide lift, instead, the air is flowing upwards. When the a/c is a slow moving condition under heavy weight and/or high power setting and/or zero wind, the tip vorticies will increase so much that the vortices meet up with the inner upflowing air and circulate as a donut and increases greatly until the a/c is unresponsive in flight control inputs. The pilot will recognize that "he was into wind if there was wind, he had power coming in as normal, and the rate of descent on approach was carefully monitored. You can call this VORTEX RING STATE.

 

As for Settling With Power, well, it's exactly what it is called. Settling With Power is completely PILOT INDUCED! Your first warning is the a/c will start to feel slightly slow to respond, immediatly to follow will be the 'shuddering', then the controls will feel lagging and/or sloppy. and of coarse the sinking increasing rate of descent, not getting better by you adding collective.

You caused this because of not being into wind and/or, high rate of descent and/or low airspeed w/ low power setting. These are totally PILOT controlled characteristics.

 

You can not call them the same. Or can can You Meant to mean that. They are different.

 

To correct either one, it is the same recovery technique. Lower collective if altitude permits, move a/c to the side or forward, to get airspeed, or clean air.

 

Anyone disagrees, please feel free to correct me.

 

Ceez.

 

 

??? :o

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If there was a great difference between SWP and VRS, we as pilots would know the answers to these great questions.

Aerodynamic physicists can argue all day about the subtle differences of the vectors, resultants and coefficients.

So, I don't have a mass-debate with myself in the cockpit as to what aerodynamic nuance I'm dealing with.

 

The causes are usually the same, and the cure is identical.

We as pilots must know how to avoid them, and how to recover from them.

 

Basically the rotor system is moving into its own downwash, therefore the blades are trying to get traction on some really crappy disturbed air.

 

So how does this happen ???????

If you are landing in a tailwind, the downwash will be blown under your rotor system instead of trailing behind you.

If you descend at the same rate as your downwash, your blades will be 'spinning their wheels'.

Therefore it won't happen at a high rate of descent because your downwash is going UP through the rotor system while your aircraft is going DOWN.

It won't occur if you descend very slowly with high power, because you are gently lowering yourself down on top of that cushion of downwash.

 

The tail rotor is just another rotor system, so the same thing happens to it.

If you do a hover turn into the tail's downwash, or blow the crappy air (coming out from the main rotor) into the tail rotor, you will get LTE.

 

I think LTE, SWP and VRS are all basically the same thing! (i.e. trying to fly in crappy air).

But because we have different controls for the tail, we get into LTE differently than SWP and VRS.

Because of when LTE usually happens (very short final) there is often no recovery time available.

 

The cures for SWP and VRS are the same.....move the rotor system into some undisturbed air.

But this is not as easy as it sounds, because the cyclic and collective aren't very efficient at that moment !!! Combine that with a descent towards the planet Earth and you are getting into a real pickle !!!

 

If you lift the collective, it won't do much for you in that crappy air, and the torque gauge won't go up much because there is no real drag against the blades.

Hopefully you have enough altitude and a little bit of disc control, so that moving the cyclic forward will let you fall out of that descending column of air into some good stuff.

At this moment the blades will get traction again....and if you have lots of pitch on the blades because you raised the collective.....the torque gauge will SPIKE !!

 

So, as with a lot of our job, avoidance is much better than recovery.

 

If you have done a power check as Deuce mentioned (hover out of ground effect in clear air) and found you have sufficient 'lift' to overcome 'weight' then there should no problem landing in a hole.....if you descend slowly. But if you descend at the same rate as your rotor's downwash you will start to 'settle'. Whether the vortices are forming a 'ring' around the blade tips or not is irrelevant to me !! We can leave that to the accident investigators and physicists to discuss.

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Over-Talk. You say you don't care about the subtle differences of either nuisiance. Just learn how to avoid them. How can you avoid them if you know nothing more then they are a nuisiance?

You are a commercial pilot (hopefully), and getting paid well for being one. It is my understanding that one should know every aspect of thier job, JUST because it pertains to their job.

 

Do you think a heart surgeon of brain surgeon would have that mentality? How about a lawyer? To be a respected pilot amongest peers, one would be open to learning and KNOWING subtle differences about their job. A junior pilot would only be as good as the instructor, or "experienced" pilot leading the junior.

 

You are obviously a good pilot since you have a mass of yrs of experience to back what YOU say, however you like me, can always be better.

 

Knowledge is power. No matter what arguement.

 

Ceez.

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I think that last few posts have clearly delineated the debate: Are VRS and SWP the same, or different?

 

Deuce (how ya doin', buddy?) more-or-less nailed it in his original post. HG adds an important point by characterizing SWP as a power management issue. I find the "100km/hr" example a bit misleading, though. SWP can happen at slow speeds: A slow, downwind turn out of translation comes to mind. The descent rate may be slow (not VRS), but in SWP there won't be enough power to control the descent or stop at the bottom.

 

Either way, VRS and SWP are two (or one :)) good reason to resist the temptation, or pressure, to hurry an approach.

 

Dick

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South of the border (i.e., in the U.S.) "vortex ring state" and "settling with power" are used interchangeably. In fact, the table of contents for the FAA Rotorcraft Flying Handbook lists "Vortex Ring State (Settling With Power)." I'm not sure if Americans have a good term for what the rest of the world calls "settling with power," unless it's "Oh s***!"

 

Anyway, while it would be helpful to have two distinct terms for two distinct phenomena, this might be a case where imprecise popular usage simply takes over... we Americans are great at muddying the waters. ;)

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