Calling Nick Lappos - Blade Stall
AnFi - I am starting to have some sympathy with crab as it happens - you don't answer the question except in riddles and you immediately insult the intelligence of anyone who questions your theory.
An aircraft can sustain a 2G turn at Vy at just under max power at 100% RRPM - that same aircraft can generate 3G from a 130kt cruise by pulling aft cyclic, also at 100% RRPM and there is no blade stall in either case - therefroe your continued assertion that Ct/sigma max or TRT is dependent on Nr squared is false.
An aircraft can sustain a 2G turn at Vy at just under max power at 100% RRPM - that same aircraft can generate 3G from a 130kt cruise by pulling aft cyclic, also at 100% RRPM and there is no blade stall in either case - therefroe your continued assertion that Ct/sigma max or TRT is dependent on Nr squared is false.
Having just re-read the start of this tedious thread, it is quite clear that dCL blew large holes in AnFI's maths about halfway down page 2 - then Nick produced some graphs showing Ct/sigma which AnFI grabbed like a drowning man and tried to use to prove his point - it doesn't.
Thereafter the insults flew (and yes, guilty as charged for part of that) and a circular argument ensued.
The problem is that AnFi has produced (or developed) a theory that is based on NO PROOF whatsoever, no empirical test data, no academic or scientific papers, no accident reports and not even any anecdotal eveidence - only the flaky maths that don't deal with 'insignificant or irrlevant (according to him) factors.
And the invented justification that knowledge of this mythical UCA might prevent pilots from crashing into the ground is about as useful as expecting rainbow-coloured unicorns to give you more lift when you have made a mees of things.
Btw AnFi this isn't pricking your pomposity - we are way past that as you don't feel any sense of humility, shame or embarrasment.
If I had such a random idea as UCA, I would probably PM some of our learned contributors to see what they thought or try contacting aircraft designers for opinion. I certainly wouldn't parade my stream of consciousness on this forum and try to propose it as fact. The Emperor's New Clothes springs to mind...
Thereafter the insults flew (and yes, guilty as charged for part of that) and a circular argument ensued.
The problem is that AnFi has produced (or developed) a theory that is based on NO PROOF whatsoever, no empirical test data, no academic or scientific papers, no accident reports and not even any anecdotal eveidence - only the flaky maths that don't deal with 'insignificant or irrlevant (according to him) factors.
And the invented justification that knowledge of this mythical UCA might prevent pilots from crashing into the ground is about as useful as expecting rainbow-coloured unicorns to give you more lift when you have made a mees of things.
Btw AnFi this isn't pricking your pomposity - we are way past that as you don't feel any sense of humility, shame or embarrasment.
If I had such a random idea as UCA, I would probably PM some of our learned contributors to see what they thought or try contacting aircraft designers for opinion. I certainly wouldn't parade my stream of consciousness on this forum and try to propose it as fact. The Emperor's New Clothes springs to mind...
Join Date: Aug 2003
Location: Sale, Australia
Age: 80
Posts: 3,832
Likes: 0
Received 0 Likes
on
0 Posts
No official accident reports mention limit of Rotor Thrust being the cause. You are right, Strange when there are so many accidents like that, you'd have thought 'they'd' notice.
I think they just say if you hit the ground then you were too low
I think they just say if you hit the ground then you were too low
Join Date: Dec 2008
Location: N/A
Posts: 845
Likes: 0
Received 0 Likes
on
0 Posts
If it's not interesting to you then please don't engage. Stalking and insulting has only prolonged the difficulty in explaining the point.
-------------------------------------------------------------------------------------------------------------------------------------------------------------
Let's try this , open question
if a Rotor can only make enough thrust to pull 3g when light
and it's 1g coning angle is 3degress
then what coning angle would it have at 3g ??
Answer 9degress
supplimentary question
if the helicopter weighs twice as much and the Rotor is capable of the same thrust then it can only pull 1.5g
What would the coning angle be?
Answer 9degrees
ie same coning angle 'UCA'
-------------------------------------------------------------------------------------------------------------------------------------------------------------
there are accidents where the rotor has hit it's max thrust (regardless of energy). 2Apaches, 1 H269(possible energy issues too), 1 NH90
(we're talking about the rotor capability, not the engine's ability to supply that energy/s)
-------------------------------------------------------------------------------------------------------------------------------------------------------------
please don't reply if you just want to say how uninteresting it is to you. Crab your noise has degraded the quality of engagement here.
If 'the expert' says it's not true because the Greek helicopter was 20-30kts and it would have to be Vy or above and it turns out that the speed of the Greek helicopter was in fact about 90kts and the expert was wrong then it is only fair to make that point. eh?
Fact shouldn't be determined by popularity contest.
-------------------------------------------------------------------------------------------------------------------------------------------------------------
Let's try this , open question
if a Rotor can only make enough thrust to pull 3g when light
and it's 1g coning angle is 3degress
then what coning angle would it have at 3g ??
Answer 9degress
supplimentary question
if the helicopter weighs twice as much and the Rotor is capable of the same thrust then it can only pull 1.5g
What would the coning angle be?
Answer 9degrees
ie same coning angle 'UCA'
-------------------------------------------------------------------------------------------------------------------------------------------------------------
there are accidents where the rotor has hit it's max thrust (regardless of energy). 2Apaches, 1 H269(possible energy issues too), 1 NH90
(we're talking about the rotor capability, not the engine's ability to supply that energy/s)
-------------------------------------------------------------------------------------------------------------------------------------------------------------
please don't reply if you just want to say how uninteresting it is to you. Crab your noise has degraded the quality of engagement here.
If 'the expert' says it's not true because the Greek helicopter was 20-30kts and it would have to be Vy or above and it turns out that the speed of the Greek helicopter was in fact about 90kts and the expert was wrong then it is only fair to make that point. eh?
Fact shouldn't be determined by popularity contest.
Join Date: Jan 2011
Location: on the cusp
Age: 52
Posts: 217
Likes: 0
Received 0 Likes
on
0 Posts
My point about collective is that according to the original proposition, max lift is at the "ultimate coning angle" and this value is self-limiting. Therefore the pilot is free to request as much collective as they wish, the lift will max out at this limit. The only thing then determining the available thrust at this point is the rotor speed.
I question your source of "fact" about the speed of the Apache in the clip. So far you've only referenced your opinion. If we ever see it, the data recorder should clarify. My opinion is (with substantial error bars) is about 45 knots. Please quote your source of the data so we can peer review. As you say, facts are facts.
I question your source of "fact" about the speed of the Apache in the clip. So far you've only referenced your opinion. If we ever see it, the data recorder should clarify. My opinion is (with substantial error bars) is about 45 knots. Please quote your source of the data so we can peer review. As you say, facts are facts.
I am actually interested AnFi but you seem incapable of answering anyone's questions.
Instead you ask your own
to which only you appear to know the 'answer' - again based on your shaky theory and maths and absolutely NOTHING else.
Instead you ask your own
Let's try this , open question
if a Rotor can only make enough thrust to pull 3g when light
and it's 1g coning angle is 3degress
then what coning angle would it have at 3g ??
Answer 9degress
supplimentary question
if the helicopter weighs twice as much and the Rotor is capable of the same thrust then it can only pull 1.5g
What would the coning angle be?
Answer 9degrees
ie same coning angle 'UCA'
if a Rotor can only make enough thrust to pull 3g when light
and it's 1g coning angle is 3degress
then what coning angle would it have at 3g ??
Answer 9degress
supplimentary question
if the helicopter weighs twice as much and the Rotor is capable of the same thrust then it can only pull 1.5g
What would the coning angle be?
Answer 9degrees
ie same coning angle 'UCA'
the difficulty in explaining the point.
Your exam question above - have you actually measured this increase in coning vs G loading or coning angle vs AUM? Have you any actual data to support your answer?
Join Date: Dec 2008
Location: N/A
Posts: 845
Likes: 0
Received 0 Likes
on
0 Posts
Crab
"I am actually interested AnFi"
i wish you were, if you are you have a strange way of going about it
ok then
re coning 'maths exam', it's only arithmetic (and it's not exact but it uses accepted approximations, like arctan(a/b) = a/b for small angles)
The relevant arithmetic is
c=a/b
so if a doubles then c doubles
if b halves then c also doubles
if a and b both double then c STAYS THE SAME
which questions do you think I havn't answered?
(mostly many times in many ways, and then I get criticised for when I try to patiently explain answers, you can see the discussion does some good, (African!), and even if just to get people thinking it through)
why don't you see what the point is and take it from there? most people think its about Ca getting bigger when the RRPM goes down, but surprisingly it gets bigger because the Cl has gone up! Clmax being the useful limit and the point where UCA will be acheived regardless of RRPM.
dc/da
"Please quote your source of the data so we can peer review. As you say, facts are facts. "
as I say I measured 5.25 a/c lengths in the arc that took 2seconds, using aircraft length 58ft
That has error bars on it too, I'd say 10%, so it's definately not 45kts, try it on a calculator or try the measurment yourself.
How big are YOUR error bars? 80% would be unreasonable!! and anyway this isn't about the Greek Helicopter !!
and
you say "max lift is at the "ultimate coning angle" and this value is self-limiting. Therefore the pilot is free to request as much collective as they wish,"
Not really, because you are muddying the water (like the Apache did!) with running into the engine limit to deliver the energy required. When Clmax is hit and so UCA reached the energy consumption rate goes up, if you are able to fund this with Potential Energy and Kinetic Energy then you'll just sit at UCA/CLmax, while you can continue to do it. So in a sense it is self limiting to a degree, discovering this limit is when the pilot realises that his increased pitchup rate does not give more TRT for increased energy input, it just funds an increased Cd . If you have less Cl then you have less coning too, so coning will only ever get to where Clmax takes it. (until you've properly stalled the blades, some way down the road, then they'll probably come off)
(you could go to a higher RRPM, and that would increase the rotor's capacity to make more TRT, if used it would make more g but it would still get stop at UCA, as it would for a lower RRPM at a lower g still at UCA)
Do the 'coning exam' please
"I am actually interested AnFi"
i wish you were, if you are you have a strange way of going about it
ok then
re coning 'maths exam', it's only arithmetic (and it's not exact but it uses accepted approximations, like arctan(a/b) = a/b for small angles)
The relevant arithmetic is
c=a/b
so if a doubles then c doubles
if b halves then c also doubles
if a and b both double then c STAYS THE SAME
which questions do you think I havn't answered?
(mostly many times in many ways, and then I get criticised for when I try to patiently explain answers, you can see the discussion does some good, (African!), and even if just to get people thinking it through)
why don't you see what the point is and take it from there? most people think its about Ca getting bigger when the RRPM goes down, but surprisingly it gets bigger because the Cl has gone up! Clmax being the useful limit and the point where UCA will be acheived regardless of RRPM.
dc/da
"Please quote your source of the data so we can peer review. As you say, facts are facts. "
as I say I measured 5.25 a/c lengths in the arc that took 2seconds, using aircraft length 58ft
That has error bars on it too, I'd say 10%, so it's definately not 45kts, try it on a calculator or try the measurment yourself.
How big are YOUR error bars? 80% would be unreasonable!! and anyway this isn't about the Greek Helicopter !!
and
you say "max lift is at the "ultimate coning angle" and this value is self-limiting. Therefore the pilot is free to request as much collective as they wish,"
Not really, because you are muddying the water (like the Apache did!) with running into the engine limit to deliver the energy required. When Clmax is hit and so UCA reached the energy consumption rate goes up, if you are able to fund this with Potential Energy and Kinetic Energy then you'll just sit at UCA/CLmax, while you can continue to do it. So in a sense it is self limiting to a degree, discovering this limit is when the pilot realises that his increased pitchup rate does not give more TRT for increased energy input, it just funds an increased Cd . If you have less Cl then you have less coning too, so coning will only ever get to where Clmax takes it. (until you've properly stalled the blades, some way down the road, then they'll probably come off)
(you could go to a higher RRPM, and that would increase the rotor's capacity to make more TRT, if used it would make more g but it would still get stop at UCA, as it would for a lower RRPM at a lower g still at UCA)
Do the 'coning exam' please
Join Date: Jan 2011
Location: on the cusp
Age: 52
Posts: 217
Likes: 0
Received 0 Likes
on
0 Posts
So AnFI, just an opinion, not a fact then.
My estimate, for my opinion, is based on the two electricity pylons seen on the hillside. These can be seen on aerial photography of the region. Using a GIS their position can be obtained and therefore the distance between them. I compared the length of the Apache, obtained from public info, to that apparent distance between the pylons. This allowed me to calculate a scale factor (similar triangles). From that I could determine how far the aircraft had traveled in the last second before the impact. Something like 23m.
My estimate, for my opinion, is based on the two electricity pylons seen on the hillside. These can be seen on aerial photography of the region. Using a GIS their position can be obtained and therefore the distance between them. I compared the length of the Apache, obtained from public info, to that apparent distance between the pylons. This allowed me to calculate a scale factor (similar triangles). From that I could determine how far the aircraft had traveled in the last second before the impact. Something like 23m.
The relevant arithmetic is
c=a/b
so if a doubles then c doubles
if b halves then c also doubles
if a and b both double then c STAYS THE SAME
c=a/b
so if a doubles then c doubles
if b halves then c also doubles
if a and b both double then c STAYS THE SAME
You still haven't put any actual data on here or into your equations - therefore they are just algebraic manipulation and not mathematical proof.
why don't you see what the point is and take it from there? most people think its about Ca getting bigger when the RRPM goes down, but surprisingly it gets bigger because the Cl has gone up! Clmax being the useful limit and the point where UCA will be acheived regardless of RRPM.
The whole point of presenting a theory for public scrutiny is that you provide data to support your position - this has been lacking from the start and shows no sign of being rectified.
So in a sense it is self limiting to a degree, discovering this limit is when the pilot realises that his increased pitchup rate does not give more TRT for increased energy input, it just funds an increased Cd
Join Date: Dec 2008
Location: N/A
Posts: 845
Likes: 0
Received 0 Likes
on
0 Posts
dc/da
"From that I could determine how far the aircraft had traveled in the last second before the impact."
How? By measuring the distance of the background adjacent to the tail at the begining of the last second to the position of the background adjacent to the tail against the at the end of the last second, measured as a proportion of the distance between the pylons and then applying your scale factor? If so that doesn't work because the background distance is not all at the same distance as the pylons (by a large factor), and if not how? It is very sensitive to the duration of 1 second, how did you acheive that? I did it by looping the video and timing 10runs and dividing by 10. My method is independant of the scale or distance of the backgroud, the distance unit is the Apache length at the distance of the apache. If you measure a boat travelling by seeing how many 'apparent boat lengths' it moved and multiplied by the length of the boat, you'd have found how far the boat moved, if you time it acurately you've got the speed. Did you acount for different scale horizontally to vertically? Do you know what a pitchup rate of 20deg/s feels like?
crab
its a hypothesis, based on the maths (algebra) above, on the basis of which anyone could go and measure this and discover that it is supported in reality. Just because we don't have the data doesn't mean the hypothesis is wrong.
If I hypothesised that hydraulic pressure of 1500psi would exert a force of 1500lbs on a 1in area ram and twice that for a 2in area ram, it would be a reasonable hypothesis.. Do you think what I have said makes sense as a hypothesis. Do you understand what I am trying to say, how would data help?
Do you accept that Ca=Lift/Cf ?
re Prouty
no comment
"From that I could determine how far the aircraft had traveled in the last second before the impact."
How? By measuring the distance of the background adjacent to the tail at the begining of the last second to the position of the background adjacent to the tail against the at the end of the last second, measured as a proportion of the distance between the pylons and then applying your scale factor? If so that doesn't work because the background distance is not all at the same distance as the pylons (by a large factor), and if not how? It is very sensitive to the duration of 1 second, how did you acheive that? I did it by looping the video and timing 10runs and dividing by 10. My method is independant of the scale or distance of the backgroud, the distance unit is the Apache length at the distance of the apache. If you measure a boat travelling by seeing how many 'apparent boat lengths' it moved and multiplied by the length of the boat, you'd have found how far the boat moved, if you time it acurately you've got the speed. Did you acount for different scale horizontally to vertically? Do you know what a pitchup rate of 20deg/s feels like?
crab
its a hypothesis, based on the maths (algebra) above, on the basis of which anyone could go and measure this and discover that it is supported in reality. Just because we don't have the data doesn't mean the hypothesis is wrong.
If I hypothesised that hydraulic pressure of 1500psi would exert a force of 1500lbs on a 1in area ram and twice that for a 2in area ram, it would be a reasonable hypothesis.. Do you think what I have said makes sense as a hypothesis. Do you understand what I am trying to say, how would data help?
Do you accept that Ca=Lift/Cf ?
re Prouty
no comment
Join Date: Jan 2011
Location: on the cusp
Age: 52
Posts: 217
Likes: 0
Received 0 Likes
on
0 Posts
"... So note the position of the nose wrt the background, then when the tail reaches that point wrt the background note the new position of the nose and repeat etc . ..."
" ... measuring the distance of the background adjacent to the tail at the begining of the last second to the position of the background adjacent to the tail against the at the end of the last second, measured as a proportion of the distance between the pylons and then applying your scale factor? If so that doesn't work because the background distance is not all at the same distance ... "
I made sure that I established my reference points and then calculated scale. How did you establish that in your method, as you have stated you used the background AnFI?
" ... measuring the distance of the background adjacent to the tail at the begining of the last second to the position of the background adjacent to the tail against the at the end of the last second, measured as a proportion of the distance between the pylons and then applying your scale factor? If so that doesn't work because the background distance is not all at the same distance ... "
I made sure that I established my reference points and then calculated scale. How did you establish that in your method, as you have stated you used the background AnFI?
Join Date: Aug 2003
Location: Sale, Australia
Age: 80
Posts: 3,832
Likes: 0
Received 0 Likes
on
0 Posts
Despite being asked it seems AnFI is unable to provide an example of an actual accident where he considers rotor stall to be causative, and why. Have to conclude therefore that it's all bollocks. What other conclusion could one come to?
AnFI: two points to ponder from the video.
1. The last second or so before impact is, due to change of pitch/nose attitude, something like a flare (back cyclic) which tends to increase Nr, see crab's point on that.
2. The aircraft was flying in a nose down descent after the turn/course reversal, but it was powered so the Nr would be expected to have been within normal range until the flare at the end that immediately preceded impact. What this means is that once the maneuver began, through its course reversal, and as it descended and regained speed, airspeed was not stable/constant ... and ... at that flare to level from nose down and the last pull to stop descent (too late!) airspeed was not constant during the period during which you are trying to establish 90 knots as a quantity of relevance to the event. I presume that during the descent some collective may have been increased before that last pull, but without in flight data cannot know for certain.
Just out of curiosity, when is the last time you flew a rotor over like the one the Apache attempted?
If you are going to model a flight phase, or a rotor disc phenomenon, trying to do so in the process of a dynamic maneuver seems an odd place to start.
1. The last second or so before impact is, due to change of pitch/nose attitude, something like a flare (back cyclic) which tends to increase Nr, see crab's point on that.
2. The aircraft was flying in a nose down descent after the turn/course reversal, but it was powered so the Nr would be expected to have been within normal range until the flare at the end that immediately preceded impact. What this means is that once the maneuver began, through its course reversal, and as it descended and regained speed, airspeed was not stable/constant ... and ... at that flare to level from nose down and the last pull to stop descent (too late!) airspeed was not constant during the period during which you are trying to establish 90 knots as a quantity of relevance to the event. I presume that during the descent some collective may have been increased before that last pull, but without in flight data cannot know for certain.
Just out of curiosity, when is the last time you flew a rotor over like the one the Apache attempted?
If you are going to model a flight phase, or a rotor disc phenomenon, trying to do so in the process of a dynamic maneuver seems an odd place to start.
If I hypothesised that hydraulic pressure of 1500psi would exert a force of 1500lbs on a 1in area ram and twice that for a 2in area ram, it would be a reasonable hypothesis.. Do you think what I have said makes sense as a hypothesis. Do you understand what I am trying to say, how would data help?
By contrast, you have just a hypothesis with no data to prove it - that is the prime weakness in your argument but you don't have the courage to admit it.
I think Brian has the conclusion spot on.
dCL has show how the use of real accuracy - measuring a physical distance in the background - uses actual data to put forward an assessment of the apache speed. You used no such data and claimed you are accurate because you looped the video and measured it 10 times - if what you are measuring isn't right then no matter how many times you do it, you will get the wrong answer.
You have previously dismissed this speed assessment as irrelevant to the argument - which it is - but you made such a big deal about how Nick's estimate was so wrong, in an attempt to discredit his criticism of your pet theory, that it has become the pivotal issue on your claims of accuracy and credibility.
You might have noticed a distinct lack of sympathetic or supportive posts in the last few pages - does that not tell you anything????
This thread is becoming reminiscent of trying to debate with an avid member of Scientology - When someone is unable or unwilling to distinguish between fact and fiction little will be achieved.
El Ron Hubbard would be proud
El Ron Hubbard would be proud
Guest
Posts: n/a
AnFI. Before you post back, just look carefully at these last few posts, particularly Lonewolf and Brian.
Your original observation was that when the disc is producing the maximum lift that it can, then (all other things being held the same) it will be at its most coned. So far so good. The problem is you've then tried to say that the max coning will happen independent of rrpm. Maybe, maybe not, probably not actually, but actually who cares ? As lonewolf says, in a governed machine, the vast majority of this manoeuvre would have been performed at constant rrpm anyway.
So IF (and that's a huge IF without any actual evidence) this manoeuvre managed to power the disc past the linear part of the lift curve (the end of the pull more get more party), the coning angle might indeed have maxed out briefly. Well done, as Ascend Charlie would say, what a clever little secretary. As a tribute to your persistence we could call that the UCA @ 100% or AnFi's limiting angle if you really need an ego boost.
But that dynamic situation (IF it occurred) would have only lasted until the flare ran out of steam, because we all now know that the engines alone cannot power the disc to stall (Thanks Nick !). At that point other phenomena would have kicked in, or to put it colloquially, the pooch was screwed.
AnFI feel free to take credit (from me and AC anyway) for the original observation, but realise you've stretched it way beyond its ability carry useful weight.
Maybe Crab or Lonewolf can finish of with a coda from personal experience which tells us what it feels like when you get close to or maybe even past the linear part of the lift curve. And then we can all sit down with a cup of tea and be friends again.
Your original observation was that when the disc is producing the maximum lift that it can, then (all other things being held the same) it will be at its most coned. So far so good. The problem is you've then tried to say that the max coning will happen independent of rrpm. Maybe, maybe not, probably not actually, but actually who cares ? As lonewolf says, in a governed machine, the vast majority of this manoeuvre would have been performed at constant rrpm anyway.
So IF (and that's a huge IF without any actual evidence) this manoeuvre managed to power the disc past the linear part of the lift curve (the end of the pull more get more party), the coning angle might indeed have maxed out briefly. Well done, as Ascend Charlie would say, what a clever little secretary. As a tribute to your persistence we could call that the UCA @ 100% or AnFi's limiting angle if you really need an ego boost.
But that dynamic situation (IF it occurred) would have only lasted until the flare ran out of steam, because we all now know that the engines alone cannot power the disc to stall (Thanks Nick !). At that point other phenomena would have kicked in, or to put it colloquially, the pooch was screwed.
AnFI feel free to take credit (from me and AC anyway) for the original observation, but realise you've stretched it way beyond its ability carry useful weight.
Maybe Crab or Lonewolf can finish of with a coda from personal experience which tells us what it feels like when you get close to or maybe even past the linear part of the lift curve. And then we can all sit down with a cup of tea and be friends again.
Last edited by puntosaurus; 26th Oct 2016 at 11:22. Reason: Apostrophe in the wrong place, don't want the pprune grammar police on my case.
Join Date: Dec 2008
Location: N/A
Posts: 845
Likes: 0
Received 0 Likes
on
0 Posts
Ooh
so many points to come back on with that tirade of criticism
but I'll try, many of them are repetition
BA you might have missed it but I did list some well know incidents by shorthand "there are accidents where the rotor has hit it's max thrust (regardless of energy). 2Apaches, 1 H269(possible energy issues too), 1 NH90" , re a load of bollox, fair enough, different opinion about that, see Punto below.
Lone
point 1 the Nr would have stayed stable due (as Punto rightly points out) due to governing, until the probable excessive pitch pull at the end, which would not have helped, and through the droop the coning would have stayed at UCA (or slightly below, according to NL)
point 2 already covered, yes the speed I gave was the average speed, indicating that it must have been greater at some stage and less at others, also the pitchup rate is also an average with the same consequence, an average pitchup rate of 21deg/s is quite meaty and produces 3g at 90kts, clearly beyond the capability of the rotor even if energy funded adequately.
(ask yourself why, if the rotor had more capacity to produce thrust, the pilot didn't bother using it? Max Pitch rate? I don't think so)
Ref My experience in these manoeuvers, not going there, as previously flogged to death.
Ref Dynamic manoeuver, odd place to start, well the example that led to this discussion was one, so that's where it started, the averages and the nature of averaging shows that those average vales must have been exceeded or held, so it's not such a detriment.
dc/da
You have not answered any of my questions. Yet keep asking. I take it that by implication you agree with my summary of your method, I think your method is invalid, for the reasons stated. My method does not fall foul of that error because in each instance the actual distance on the background that the helicopter travels is eliminated. You could compare it to the stars, and it wouldn't matter how far away the stars were. An Airliner at an unknow height, covers an arbitrary distance against the stars behind, but if you measure tail to nose how many aircraft lenghts it covers in a time you can derive the speed, the actual distance bewteen stars would be irrelevant and introduce error. There is a 'ruler in the sky' in units of aircraft length, which is conveniently placed at the arbitrary distance of the aircraft. If the aircraft and the ruler are at the same distance you don't have to 'scale' the ruler. It might help if you could answer some of my questions. Do you agree with the 'coning exam' arithmetic? Have you seen the 2sec loop video I posted?
Crab
1 if you think it is bollox then you don't think it is interesting as you have also said. If you think it is bollox the we know where you are with it, opinion noted, no need for you to add more.
2 wrt your opinion that dc/da's method is right I refer you to my answer to him, he is wrong and you agree with him, so you are wrong again too. The thing that is sensitive to being measured 10 times is the timing, since it is such a sensitve number in the denominator. dc/da has not answered THAT either !!!! Have you seen the loop video I posted? Do you agree with the arithmetic of coning, in the coning exam? Yes that coning arithmetic is well covered and well known.
You have not answered any of the questions I have asked you either. "Do you understand what I am trying to say, how would data help? Do you accept that Ca=Lift/Cf ?"
"dismissed this speed assessment as irrelevant to the argument - which it is - but you made such a big deal about how Nick's estimate was so wrong, in an attempt to discredit his criticism of your pet theory," not dissmissed, just said that the Greek helicopter is incidental to the point. No no big deal that NL was wrong at his speed guess (actually quite the opposite, I said it is an easy error to make, understandable, look at an F1 car etc, no interest to discredit him, much of what he said was very good and I said so, but not addressing the point, which he did not address. So I have not disagreed with him. If he was wrong about the speed then it's ok to say so I think. anyone can be wrong. He did say for me to be right the speed would have to be in excess of Vy, now we know that is the case, just) (what is the Vy of an Apache?))
BellR
yes sorry about that. but to address a specific issue here one has to wade through alot of treacle.
Punto
ref Looked back esp BA and Lone. Yes done and addressed above.
Yes everything else you say is as close to correct as it's not worth argueing with (with the possible exception of "Maybe, maybe not, probably not actually, but actually who cares ?"). you seem to be one of the few that understand the point, as to whether it's interesting or not is a matter of personal opinion.
"personal experience which tells us what it feels like when you get close to or maybe even past the linear part of the lift curve." I can tell you that, vibration goes up, TRT is not increased, your path no longer continues to alter at the rate your brain would extrapolate to, pulling the lever up more doesn't help, you are grateful that you had more height margin than you thought was neccessary (credit to Crab for that observation) "(the end of the pull more get more party)"
'Cup of tea' anyone?
so many points to come back on with that tirade of criticism
but I'll try, many of them are repetition
BA you might have missed it but I did list some well know incidents by shorthand "there are accidents where the rotor has hit it's max thrust (regardless of energy). 2Apaches, 1 H269(possible energy issues too), 1 NH90" , re a load of bollox, fair enough, different opinion about that, see Punto below.
Lone
point 1 the Nr would have stayed stable due (as Punto rightly points out) due to governing, until the probable excessive pitch pull at the end, which would not have helped, and through the droop the coning would have stayed at UCA (or slightly below, according to NL)
point 2 already covered, yes the speed I gave was the average speed, indicating that it must have been greater at some stage and less at others, also the pitchup rate is also an average with the same consequence, an average pitchup rate of 21deg/s is quite meaty and produces 3g at 90kts, clearly beyond the capability of the rotor even if energy funded adequately.
(ask yourself why, if the rotor had more capacity to produce thrust, the pilot didn't bother using it? Max Pitch rate? I don't think so)
Ref My experience in these manoeuvers, not going there, as previously flogged to death.
Ref Dynamic manoeuver, odd place to start, well the example that led to this discussion was one, so that's where it started, the averages and the nature of averaging shows that those average vales must have been exceeded or held, so it's not such a detriment.
dc/da
You have not answered any of my questions. Yet keep asking. I take it that by implication you agree with my summary of your method, I think your method is invalid, for the reasons stated. My method does not fall foul of that error because in each instance the actual distance on the background that the helicopter travels is eliminated. You could compare it to the stars, and it wouldn't matter how far away the stars were. An Airliner at an unknow height, covers an arbitrary distance against the stars behind, but if you measure tail to nose how many aircraft lenghts it covers in a time you can derive the speed, the actual distance bewteen stars would be irrelevant and introduce error. There is a 'ruler in the sky' in units of aircraft length, which is conveniently placed at the arbitrary distance of the aircraft. If the aircraft and the ruler are at the same distance you don't have to 'scale' the ruler. It might help if you could answer some of my questions. Do you agree with the 'coning exam' arithmetic? Have you seen the 2sec loop video I posted?
Crab
1 if you think it is bollox then you don't think it is interesting as you have also said. If you think it is bollox the we know where you are with it, opinion noted, no need for you to add more.
2 wrt your opinion that dc/da's method is right I refer you to my answer to him, he is wrong and you agree with him, so you are wrong again too. The thing that is sensitive to being measured 10 times is the timing, since it is such a sensitve number in the denominator. dc/da has not answered THAT either !!!! Have you seen the loop video I posted? Do you agree with the arithmetic of coning, in the coning exam? Yes that coning arithmetic is well covered and well known.
You have not answered any of the questions I have asked you either. "Do you understand what I am trying to say, how would data help? Do you accept that Ca=Lift/Cf ?"
"dismissed this speed assessment as irrelevant to the argument - which it is - but you made such a big deal about how Nick's estimate was so wrong, in an attempt to discredit his criticism of your pet theory," not dissmissed, just said that the Greek helicopter is incidental to the point. No no big deal that NL was wrong at his speed guess (actually quite the opposite, I said it is an easy error to make, understandable, look at an F1 car etc, no interest to discredit him, much of what he said was very good and I said so, but not addressing the point, which he did not address. So I have not disagreed with him. If he was wrong about the speed then it's ok to say so I think. anyone can be wrong. He did say for me to be right the speed would have to be in excess of Vy, now we know that is the case, just) (what is the Vy of an Apache?))
BellR
yes sorry about that. but to address a specific issue here one has to wade through alot of treacle.
Punto
ref Looked back esp BA and Lone. Yes done and addressed above.
Yes everything else you say is as close to correct as it's not worth argueing with (with the possible exception of "Maybe, maybe not, probably not actually, but actually who cares ?"). you seem to be one of the few that understand the point, as to whether it's interesting or not is a matter of personal opinion.
"personal experience which tells us what it feels like when you get close to or maybe even past the linear part of the lift curve." I can tell you that, vibration goes up, TRT is not increased, your path no longer continues to alter at the rate your brain would extrapolate to, pulling the lever up more doesn't help, you are grateful that you had more height margin than you thought was neccessary (credit to Crab for that observation) "(the end of the pull more get more party)"
'Cup of tea' anyone?