Power settling?
Guest
Posts: n/a
The term settling is certainly not in dispute, we could easily settle on a definition (Ouch!) but the idea that power settling means too little power is not just cross-wise to current usage, it is logically backwards.
In the case where you pull up the collective and not enough engine exists to cash the check, the term could be "falling through" which is a term we used in Vietnam to describe the foolish attempt to become OGE with IGE power.
This term also tells what it feels like, is not confused with any vrs/settling terms.
The concept of something being pilot error is not worthy of our consideration. Let he who is innocent cast the first stone. Today's helos provide precious little help to the pilot.
In Comanche and S-92, the torque gauge is marked with two variable indices which are computer updated. One marks the power available from the engines under current conditions (alt, temp, engine degradation), the other marks the power required to hover OGE under current conditions (alt, temp, gross weight). If the required is below the available, you are cool, and will not fall through. If not, try to not be terminating OGE.
In the case where you pull up the collective and not enough engine exists to cash the check, the term could be "falling through" which is a term we used in Vietnam to describe the foolish attempt to become OGE with IGE power.
This term also tells what it feels like, is not confused with any vrs/settling terms.
The concept of something being pilot error is not worthy of our consideration. Let he who is innocent cast the first stone. Today's helos provide precious little help to the pilot.
In Comanche and S-92, the torque gauge is marked with two variable indices which are computer updated. One marks the power available from the engines under current conditions (alt, temp, engine degradation), the other marks the power required to hover OGE under current conditions (alt, temp, gross weight). If the required is below the available, you are cool, and will not fall through. If not, try to not be terminating OGE.
What is wrong with the term overpitching for the situation Nick describes, where the collective position writes a cheque that the engine power can't cash - the Nr will slow down unless the lever is lowered but if you lower the lever you will go down faster. It is a no win situation and can be avoided by doing the sums to ensure you have an adequate power margin for landing/hovering - the standard in Brit Mil Ops is HOGE plus a 5% Thrust Margin to counter slight turbulence/ mishandling/ windshear etc
We do not use the term settling with power or power settling in UK and therefore avoid the confusion. VRS is VRS, running out of power is running out of power - c'est tout ca! Recirculation (just at the tips due to obstacles not at the root as well like VRS) can cause you to run out of power because it increases your induced flow, but you have still run out of power. If your engines torque/temp/fuel flow limit the Nr will decay (overpitching)- if they do not you will overtorque/temp (bollocking from the boss).
We do not use the term settling with power or power settling in UK and therefore avoid the confusion. VRS is VRS, running out of power is running out of power - c'est tout ca! Recirculation (just at the tips due to obstacles not at the root as well like VRS) can cause you to run out of power because it increases your induced flow, but you have still run out of power. If your engines torque/temp/fuel flow limit the Nr will decay (overpitching)- if they do not you will overtorque/temp (bollocking from the boss).
The Original Whirly
Join Date: Feb 1999
Location: Belper, Derbyshire, UK
Posts: 4,326
Likes: 0
Received 0 Likes
on
0 Posts
I thought I understood all this stuff till I read this thread; now I'm totally confused. I just remembered why I usually ignore these sort of threads. 
Guest
Posts: n/a
Crab is right, again. Overpitching has been around, and is a good term. Regarding margin above OGE power to help you really do the mission, the US Army uses 500 ft/min climb rate, which is almost 10% power margin. Power or climb might be a better margin than thrust which is weight, although any will get you safer. I have found out that a 2% power margin is needed to turn an OGE hover into a vertical climb.
Whirlybird,
Don't be confused. We have discussed the fact that Vortex Ring State has three names (settling with power, power settling, and vrs) and that we have no name for the plain old garden variety smacking of the ground when you try to terminate an approach without enough power (except in Canada, where they are reported to use settling with power). Terms have been suggested, overpitching seems to be there already.
Up to speed?
Whirlybird,
Don't be confused. We have discussed the fact that Vortex Ring State has three names (settling with power, power settling, and vrs) and that we have no name for the plain old garden variety smacking of the ground when you try to terminate an approach without enough power (except in Canada, where they are reported to use settling with power). Terms have been suggested, overpitching seems to be there already.
Up to speed?
Join Date: Mar 2002
Location: Dansaff
Posts: 175
Likes: 0
Received 0 Likes
on
0 Posts
Unless you're Canadian there should be no confusion whatsover, VRS and SWP are the same. I like the time honoured term overpitching as it sums up limited power exceedence very well. Its also very English, almost a cricket term, perhaps we can find a use for the term googly and bouncer!
Crab, even though you're a bit blue you aint so bad after all!!!
GB.
Crab, even though you're a bit blue you aint so bad after all!!!
GB.
Thread Starter
Join Date: Jun 2002
Location: Dun Laoghaire
Posts: 137
Likes: 0
Received 0 Likes
on
0 Posts
Nick,
your words to Whirly might be falling on deaf ears. She didn't seem too enthusiastic about revisiting this thread!
Irlandés
your words to Whirly might be falling on deaf ears. She didn't seem too enthusiastic about revisiting this thread!
Irlandés
Last edited by Irlandés; 25th Sep 2002 at 07:53.
What the....?
Does it really matter what the terms are?
Understand the parameters for VRS (or whatever you want to call it) and dont' mix them all together
Understand when your limited on power and why (hot, high, heavy, OEI etc) and and don't get your bird out of its own depth
Are we pilots who know our stuff or literary critics?
Understand the parameters for VRS (or whatever you want to call it) and dont' mix them all together
Understand when your limited on power and why (hot, high, heavy, OEI etc) and and don't get your bird out of its own depth
Are we pilots who know our stuff or literary critics?
Join Date: Jun 2002
Location: home and abroad
Posts: 582
Likes: 0
Received 0 Likes
on
0 Posts
Coyote, I think most of the pilots on this forum know their stuff very well. But a thread like this allows us to explore several ways of thinking about a subject and hopefully leads to a better understanding of the subject, or to another thread about a related subject. I see it as akin to the crew room chat, where every now and then I pick up a little gem that helps me improve my flying ability.
And if you get bored with it, just stop reading.
And if you get bored with it, just stop reading.
Nick ol' buddy.......if I am using "x" amount of power for my HOGE....and I apply "X + 2%".....you state I shall now ascend vertically.
I accept that statement in total.
What happens if I apply "X + 1%" or "X + 1.5%"........would I not also ascend vertically but at a slower rate ???
Or did my alcohol ravaged brain miss something....honest...I read it two or three times.....and still got the same impression that you stated a 2% power margin over OGE was required to ascend vertically from a stable OGE hover.
Now I only flew Chinooks and being tandem rotor....they defied several laws of physics and commonsense but.....it seems to me...if I apply power in excess of that required for a stable...steady OGE hover....the birdie goes up.....! What am I missing here?
Also....I assume the fancy dancy computer whizbang on the 92 requires some manual input for aircraft weight.....or you got squat switches or something that senses the actual ramp weight of the aircraft? Now assuming that same 92 is engaged in Offshore Oil Operations.....using the GIGO theory of computers....just how reliable are those performance figures going to be. (You ever seen an oilfield scale that was accurate to within a few hundred pounds per item?) Daily I get to watch some knuckle draggers stagger under the weight of their 20 lbs of baggage which consists of a Snap-On four component roll around tool box worth of tools.....stuffed into a duffle bag. The thought of having such a lovely device fills me with joy....but I know the helicopter operators will still want to ignore the numbers because that means they will have to cut one passenger or something equally silly.
I accept that statement in total.
What happens if I apply "X + 1%" or "X + 1.5%"........would I not also ascend vertically but at a slower rate ???
Or did my alcohol ravaged brain miss something....honest...I read it two or three times.....and still got the same impression that you stated a 2% power margin over OGE was required to ascend vertically from a stable OGE hover.
Now I only flew Chinooks and being tandem rotor....they defied several laws of physics and commonsense but.....it seems to me...if I apply power in excess of that required for a stable...steady OGE hover....the birdie goes up.....! What am I missing here?
Also....I assume the fancy dancy computer whizbang on the 92 requires some manual input for aircraft weight.....or you got squat switches or something that senses the actual ramp weight of the aircraft? Now assuming that same 92 is engaged in Offshore Oil Operations.....using the GIGO theory of computers....just how reliable are those performance figures going to be. (You ever seen an oilfield scale that was accurate to within a few hundred pounds per item?) Daily I get to watch some knuckle draggers stagger under the weight of their 20 lbs of baggage which consists of a Snap-On four component roll around tool box worth of tools.....stuffed into a duffle bag. The thought of having such a lovely device fills me with joy....but I know the helicopter operators will still want to ignore the numbers because that means they will have to cut one passenger or something equally silly.
Join Date: Jan 2001
Location: AB, Canada
Posts: 420
Likes: 0
Received 0 Likes
on
0 Posts
Post becoming big time anti-Canadian, thought I better step in. Gloves off.
Consensus seems that there are two effects, one where air recirculates, another where it doesn't. With both of them the helicopter descends and sufficient power to normally stop the descent is applied. Yes, in Canada we call these VRS and SWP respectively. Most of the world uses VRS. Some strange types confusingly apply at least two names to the first condition of flight mentioned. They're the ones that screwed up the terminology.
Overpitching is used elsewhere to describe the second condition. A comment was made that since its already in use why not adopt it. NEWS FLASH, same argument can be said for SWP.
There's also the 'pull out the dictionary' argument. Settling with power would mean very little if it described a condition where a small amount of power were applied. Perhaps the intent of that terminology was settling with FULL power, or settling with NORMALLY SUFFICIENT power. I'm not protecting my country, just don't see what the big deal is, eh.
Pick up stick, pick up gloves, five minutes and a game misconduct....worth it.
p.s. Not really mad, just wanted to join in.
Consensus seems that there are two effects, one where air recirculates, another where it doesn't. With both of them the helicopter descends and sufficient power to normally stop the descent is applied. Yes, in Canada we call these VRS and SWP respectively. Most of the world uses VRS. Some strange types confusingly apply at least two names to the first condition of flight mentioned. They're the ones that screwed up the terminology.
Overpitching is used elsewhere to describe the second condition. A comment was made that since its already in use why not adopt it. NEWS FLASH, same argument can be said for SWP.
There's also the 'pull out the dictionary' argument. Settling with power would mean very little if it described a condition where a small amount of power were applied. Perhaps the intent of that terminology was settling with FULL power, or settling with NORMALLY SUFFICIENT power. I'm not protecting my country, just don't see what the big deal is, eh.
Pick up stick, pick up gloves, five minutes and a game misconduct....worth it.
p.s. Not really mad, just wanted to join in.
Join Date: Mar 2002
Location: Dansaff
Posts: 175
Likes: 0
Received 0 Likes
on
0 Posts
One thing I'm not is anti Canadian, even though I still bear a scar from a lively albeit hazy night in the Asinoboa club in Medicine Hat!
My view is clear and I'll stick with my understanding, what I want to know and have asked for here, is a reference that backs up what ya'll saying. Simple.
Asking for a reference is not a UK trait but the southern rebel in me just kicks in now and then.
My view is clear and I'll stick with my understanding, what I want to know and have asked for here, is a reference that backs up what ya'll saying. Simple.
Asking for a reference is not a UK trait but the southern rebel in me just kicks in now and then.
S76Heavy
Good point and I agree with you. I was trying to emphasise that as long as you understand thats the most important thing.
Words don't seem to come out right when your having a bad hair day.....
Good point and I agree with you. I was trying to emphasise that as long as you understand thats the most important thing.
Words don't seem to come out right when your having a bad hair day.....
Love this old hairy monster!
I like calling a spade a spade, therefore I vote for calling the downward fall through your own vorticey "Vortex Ring State" 'cause that is what is happening. I reckon that all the talk of settling with power has simply confused too many people - this thread is a case in point.
And I dont find nothin "settling" about VRS at all!!
I am less a fan of the suggestion to use "over pitching" when terminating with insufficient power though. The reason is that I do like to call a spade a spade. Over pitching is still used to describe an actual state - when you have increased collective pitch to the point that RRPM begins to droop - ie you have "over pitched". I agree that this might cause you to fall through your termination, but it might also occur during take off, or especially for the piston guys, any time you have forgotten to roll a bit of throttle on when you have increased pitch.
Perhaps we could call it what it is: terminating with insufficient power! or Attempting to take off with insufficient power! Or attempting to [insert manoeuvre here] with insufficient power! How about that?
One of my old instructors used to call it "Engine failure: the engine failed to produce the squillions of horsepower required to complete the attempted manoeuvre"
I like calling a spade a spade, therefore I vote for calling the downward fall through your own vorticey "Vortex Ring State" 'cause that is what is happening. I reckon that all the talk of settling with power has simply confused too many people - this thread is a case in point.
And I dont find nothin "settling" about VRS at all!!
I am less a fan of the suggestion to use "over pitching" when terminating with insufficient power though. The reason is that I do like to call a spade a spade. Over pitching is still used to describe an actual state - when you have increased collective pitch to the point that RRPM begins to droop - ie you have "over pitched". I agree that this might cause you to fall through your termination, but it might also occur during take off, or especially for the piston guys, any time you have forgotten to roll a bit of throttle on when you have increased pitch.
Perhaps we could call it what it is: terminating with insufficient power! or Attempting to take off with insufficient power! Or attempting to [insert manoeuvre here] with insufficient power! How about that?
One of my old instructors used to call it "Engine failure: the engine failed to produce the squillions of horsepower required to complete the attempted manoeuvre"
Guest
Posts: n/a
SASless:
I base the comment about +2% for vertical takeoff on my own experience, and invite you to try it and see what happens. On a still morning in the tropics, I found that charted OEI power produced a steady 60 foot hover in an S76A. If I carefully squeezed 1% more, the aircraft went up to 70 feet and stopped, then settled down to 50 or so, then climbed back up to 70, and sort of hung there. It took+2% to keep the aircraft actually moving up and out of the hover.
If I used OGE power only and gently lowered the nose to fly away, virtually no descent occurred (unlike IGE takeofffs). I could immediately climb when I got to about 5 knots, and by 10 knots, the climb rate was very nice (maybe 300 to 500 fpm).
Conclusion: OGE power means OGE power, not vertical takeoff power.
Go ahead, ask me why 2% is needed and not 1%.
OK I'll answer your question! I dunno.
Nick
I base the comment about +2% for vertical takeoff on my own experience, and invite you to try it and see what happens. On a still morning in the tropics, I found that charted OEI power produced a steady 60 foot hover in an S76A. If I carefully squeezed 1% more, the aircraft went up to 70 feet and stopped, then settled down to 50 or so, then climbed back up to 70, and sort of hung there. It took+2% to keep the aircraft actually moving up and out of the hover.
If I used OGE power only and gently lowered the nose to fly away, virtually no descent occurred (unlike IGE takeofffs). I could immediately climb when I got to about 5 knots, and by 10 knots, the climb rate was very nice (maybe 300 to 500 fpm).
Conclusion: OGE power means OGE power, not vertical takeoff power.
Go ahead, ask me why 2% is needed and not 1%.
OK I'll answer your question! I dunno.
Nick
Thread Starter
Join Date: Jun 2002
Location: Dun Laoghaire
Posts: 137
Likes: 0
Received 0 Likes
on
0 Posts
How about this idea: In an ideal OGE hover the average inflow angle is a constant. If you bring in a small amount of power (say 1% above OGE), total rotor thrust increases slightly, enough to start a slow rate of ascent. As we know, the slow rate of descent will cause a small increase in inflow effectively trying to negate that rate of climb. Is it possible that there's a very small range of values (less than 2% above OGE) where this inflow actually succeeds in preventing a sustainable rate of climb? Instead you get this situation where the aircraft oscillates between trying to climb, realises it can't, settles back down again, tries again etc. ad infinitum. Are the terms 'phugoid' or 'hysterisis' applicable here?
I've always likened an OGE hover to being half way up a stationary escalator. If you start walking towards the top of the escalator, suddenly it starts moving down (increased inflow) but normally you're walking fast enough to make progress up the escalator to the top (OGE +2% Power). And the opposite holds true. Start walking down and the escalator starts moving up (decreased inflow) but not enough to arrest our rate of descent. We get to the bottom.
Is this total hogwash?? Be honest, I can take it!
Irlandés
I've always likened an OGE hover to being half way up a stationary escalator. If you start walking towards the top of the escalator, suddenly it starts moving down (increased inflow) but normally you're walking fast enough to make progress up the escalator to the top (OGE +2% Power). And the opposite holds true. Start walking down and the escalator starts moving up (decreased inflow) but not enough to arrest our rate of descent. We get to the bottom.
Is this total hogwash?? Be honest, I can take it!
Irlandés
