He stepped on the Rudder and redefined Va
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Horatio Barber, who flew the first aeroplane freight (Osram bulbs), wrote
"The Aeroplane Speaks"
for pilots and trainee pilots of the Royal Flying Corps in 1917. (It can be downloaded for those interested in what was taught, then.. Perhaps a HTBJ of its day.)
"The Aeroplane Speaks"
for pilots and trainee pilots of the Royal Flying Corps in 1917. (It can be downloaded for those interested in what was taught, then.. Perhaps a HTBJ of its day.)
Last edited by Linktrained; 9th Oct 2013 at 00:27.
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I have talked to and seen Bob Hoover several times and what a gentleman. Reading his book he would have had the sound barrier record if he hadn't done a buzz job that pissed off the commander so Chuck Yeager got it.
They have been at the Reno Air races the last 13 years I have been there and have Bob Hoovers autograph on his book. He used to fly into Flabob Airport in Riverside Ca. to see Art Scholl who I flew aerobatic instruction for and always landed his Shrike on one wheel even if nobody was looking. It was great flying back then. Everybody knew how to handfly and autopilots were a luxury but no one needed one. Today is different for the new people. We need to make new pilots real pilots not programers. Bottom dollar thinking probably won't let this happen again.
They have been at the Reno Air races the last 13 years I have been there and have Bob Hoovers autograph on his book. He used to fly into Flabob Airport in Riverside Ca. to see Art Scholl who I flew aerobatic instruction for and always landed his Shrike on one wheel even if nobody was looking. It was great flying back then. Everybody knew how to handfly and autopilots were a luxury but no one needed one. Today is different for the new people. We need to make new pilots real pilots not programers. Bottom dollar thinking probably won't let this happen again.
It's not like Teldoserious is unique in that regard. In fact, I'm surprised that the alleged PROFESSIONAL Pilots Rumor Network has no screening process outside of individual airline private sections. The result is posers galore.
I also value the pilots input on what we do. I've known and worked with lots of Boeing test pilots over the years - some well known, others not so much - but getting input from the guys (and gals) that fly these planes on a day to day basis has a special value.
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Dozy, I may very well be in error but I have reasons to believe flarepilot may very well be a reincarnation of our friend SSG, lately going by the Teldorserious handle. Flarepilot made the claim earlier in this thread that the Sabreliner 40 had a placard in the cockpit advising limiting control movement to 50% when above 40,000 feet. Only trouble is the operators of the aircraft I've talked to have never heard of it, and nor the FAA.
Moderator
But I do have 36 plus years experience as an engineer in Boeing Commercial Aircraft
.. which is why we don't have an exclusive pilots' club and warmly welcome folks such as your goodself to the sand pit.
.. which is why we don't have an exclusive pilots' club and warmly welcome folks such as your goodself to the sand pit.
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Originally Posted by tdracer
I know things that I'm not allowed to make public. Oftentimes it's considered [X] proprietary/sensitive, in the case of air safety investigations
Originally Posted by DozyWannabe
Doesn't matter if it behaves differently, it's still the same system.
Originally Posted by BARKINGMAD
It gives me the chills when I feel it, and I am forced to ask what are the type-rating trainers and the line trainers up to by allowing this crass, clumsy and careless handling?
Originally Posted by OK465
Not only was the subject not delicate, but there were some mil airplanes that 'required' aggressive (but smooth) use of rudder in some flight regimes. One of which had been flown extensively in the 80s by many airline captains of the 90s.
Originally Posted by AirRabbit
To me, this is what I think that F/O was doing ... reacting with a skill set and doing so out of panic ... attempting to function without thinking logically or reasoning to any degree and was, instead, functioning out of an overwhelming feeling of anxiety and frantic agitation.
Originally Posted by flarepilot
I hope this thread ends with this post.
Originally Posted by flarepilot
The real question and problem is why didn't the line pilots know?
Originally Posted by flarepilot
Doing my bit of research, the US government was quite concerned over the role many interested parties had in trying (repeat, trying) to influence the outcome of the NTSB probable cause. Were there attempts to influence? Yes. Did they influence the final report...you decide.
Originally Posted by flarepilot
The FAA has in the past known about problems with certain planes in certain conditions and have not passed the information along to the users of the planes. I can remember especially the problem with the F28 Fokker and so called ''hard wing planes''. An accident in Canada showed the problem and it was repeated three years later in the US...oops, the FAA forgot to tell the users.
Originally Posted by flarepilot
There has been more than enough hatred on this thread as to ruin the bond we share in the sky
Originally Posted by flarepilots
Engineers should think like pilots and make safeguards of every conceivable type to protect pilots from killing people.
Just ask usual contributors about evils of envelope protection
or if more realistically inclined, read DP Davies treatise on stick pushers.
Originally Posted by Machinbird
The problem is that the force and travel required to activate the rudder to its limits were minimal, and thus it was easy to excite a yaw oscillation by relatively small repetitive rudder inputs.
Sheer panic.
Originally Posted by bubbers44
A recent thread said the B787 is designed to be able to be flown by equally incompetent Airbus pilots because of it's automation.
Originally Posted by roulishollandais
What we need is a new point of view that does not exist in our regulations of certification concerning RESONANCE
Quotes from tdracer:
"I make no secret that I'm not a pilot (although I would have liked to be, and nearly was - but that's another story). But I do have 36 plus years experience as an engineer in Boeing Commercial Aircraft - working at one time or another 727, 737, 747, 757, 767, and 777. In short, I know a lot about 'how planes work' (at least Boeing planes), and I'd like to think that knowledge brings something valuable to the discussions."
Precisely the kind of input pilots need to challenge their assumptions.
"...I also value the pilots input on what we do. I've known and worked with lots of Boeing test pilots over the years - some well known, others not so much - but getting input from the guys (and gals) that fly these planes on a day to day basis has a special value."
Looking back at my unremarkable career, some of the most rewarding dialogues I had were with engineers. Some of them were grizzled flight-engineers, but right now I'm talking about ground engineers. Admittedly, in my case they were mainly line-maintenance people; except in my earlier days on conversion courses, when some of the guys teaching us a/c systems had been production engineers on the same a/c. They've all since been supplanted by CBT, and what the powers-that-be think we "need to know"; more's the pity.
"Unfortunately I often have to censor myself, because I know things that I'm not allowed to make public. Oftentimes it's considered Boeing proprietary/sensitive, in the case of air safety investigations we can get in big trouble for releasing unauthorized information before the official stuff comes out..."
roulishollandais (above) expresses the concerns of many of us, but I'm assuming that anything operators need to know urgently will be promulgated to them by the usual bulletins (senior moment: can't remember what they are called!). The only snag is that, in rare cases, the incident might not be manufacturer-specific. Operators of comparable a/c from a rival manufacturer might also need to be warned.
Speaking more generally about commercially sensitive information, there is a perception in British aviation circles that, in the past, efforts to share knowledge for mutual benefit have rarely been reciprocated by American manufacturers (without mentioning any names). It's a truism that the Brits have been better at coming up with new ideas than they are at producing something that sells in large numbers. That's why we think it's a bit rich when Boeing supporters fume about Airbus's sales successes.
Perhaps, in some after-life, all you Boeing and Airbus engineers - not to mention the Russians and all the others - will get together, realise how similar your aspirations and expertise are, and create even better aircraft. But that kind of cosy, utopian relationship is not, admittedly, what got Apollo 11 to the Moon and back.
"I make no secret that I'm not a pilot (although I would have liked to be, and nearly was - but that's another story). But I do have 36 plus years experience as an engineer in Boeing Commercial Aircraft - working at one time or another 727, 737, 747, 757, 767, and 777. In short, I know a lot about 'how planes work' (at least Boeing planes), and I'd like to think that knowledge brings something valuable to the discussions."
Precisely the kind of input pilots need to challenge their assumptions.
"...I also value the pilots input on what we do. I've known and worked with lots of Boeing test pilots over the years - some well known, others not so much - but getting input from the guys (and gals) that fly these planes on a day to day basis has a special value."
Looking back at my unremarkable career, some of the most rewarding dialogues I had were with engineers. Some of them were grizzled flight-engineers, but right now I'm talking about ground engineers. Admittedly, in my case they were mainly line-maintenance people; except in my earlier days on conversion courses, when some of the guys teaching us a/c systems had been production engineers on the same a/c. They've all since been supplanted by CBT, and what the powers-that-be think we "need to know"; more's the pity.
"Unfortunately I often have to censor myself, because I know things that I'm not allowed to make public. Oftentimes it's considered Boeing proprietary/sensitive, in the case of air safety investigations we can get in big trouble for releasing unauthorized information before the official stuff comes out..."
roulishollandais (above) expresses the concerns of many of us, but I'm assuming that anything operators need to know urgently will be promulgated to them by the usual bulletins (senior moment: can't remember what they are called!). The only snag is that, in rare cases, the incident might not be manufacturer-specific. Operators of comparable a/c from a rival manufacturer might also need to be warned.
Speaking more generally about commercially sensitive information, there is a perception in British aviation circles that, in the past, efforts to share knowledge for mutual benefit have rarely been reciprocated by American manufacturers (without mentioning any names). It's a truism that the Brits have been better at coming up with new ideas than they are at producing something that sells in large numbers. That's why we think it's a bit rich when Boeing supporters fume about Airbus's sales successes.
Perhaps, in some after-life, all you Boeing and Airbus engineers - not to mention the Russians and all the others - will get together, realise how similar your aspirations and expertise are, and create even better aircraft. But that kind of cosy, utopian relationship is not, admittedly, what got Apollo 11 to the Moon and back.
Last edited by Chris Scott; 9th Oct 2013 at 14:35. Reason: Omission of F/Es corrected.
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roulis
Pas d'accord! Well not entirely d'accord anyway.
My gripe is that the pilot giving a second oscillation is actually the problem since it is the pilot actions that in this case start off or aggravate the resonance.There are folks here that would think it presumptuous for a mere engineer, no matter how well qualified, to offer any advice on how to fly airplanes, but luckily Dave Davies has already done it, very concisely and very precisely:
Clearly, Davies at least regards the correct method as a type of open loop process. Note also his remarks on the difficulty of suppressing dutch roll oscillations by the use of rudder.
I know very well that if a pilot decides to actively control a dutch roll using aileron then unless he properly adapts his internal transfer function to match the open loop dynamics of the airframe there is a risk that at some value of pilot gain the root locus of the closed loop system might cross over into the negative damping region. [That piece of jargon ridden technological gobbledygook translates as "If the pilot tries to chase the dutch roll and gets his timing wrong he could end up in a PIO or APC situation"]
From what you have written this might have been the case on that Learjet?
Here I do disagree with you. The object of certification is to avoid any resonance not devise rules to tame it. In fact the existing regulations do just that:
Part 23, against which I believe that Learjet to be certificated, is slightly different :
If that aeroplane was a susceptible to dutch roll problems as your posts suggest then it must be on the limit for certification surely? Arguing from that case to a need for another set of requirements strikes me as an extrapolation from the particular to the general - and rather like extrapolating from a single spot point, that is a dodgy process.
Pas d'accord! Well not entirely d'accord anyway.
and the pilot gives a second oscillation to try to stop the dutch roll "problem", starting resonance.
The control of divergent dutch roll is not difficult so long as it is handled properly. Let us assume that your aeroplane develops a diverging dutch roll. The first thing to do is nothing - repeat nothing. Too many pilots have grabbed the aeroplane in a rush, done the wrong thing and made matters a lot worse. Don't worry about a few seconds delay because it won't get much worse in this time. Just watch the rolling motion and get the pattern fixed in your mind. Then, when you are good and ready, give one firm but gentle correction on the aileron control against the upcoming wing. Don't hold it on too long - just in and out - or you will spoil the effect. You have then, in one smooth controlled action, killed the biggest part of the roll. You will be left with a residual wiggle, which you can take out, still on ailerons alone, in your own time.
Don't attempt to correct the manoeuvre with rudder; as explained, the yaw is often suppressed and it is difficult to work out which way to apply the rudder at what particular moment and there is a good chance that the wrong rudder will be applied which will aggravate things very quickly. It is not difficult, however to apply the correct aileron control. Further, don't attempt to squash the dutch roll flat in one fell swoop but be content with taking out a big bite first time then sorting out the remainder next time
Don't attempt to correct the manoeuvre with rudder; as explained, the yaw is often suppressed and it is difficult to work out which way to apply the rudder at what particular moment and there is a good chance that the wrong rudder will be applied which will aggravate things very quickly. It is not difficult, however to apply the correct aileron control. Further, don't attempt to squash the dutch roll flat in one fell swoop but be content with taking out a big bite first time then sorting out the remainder next time
I know very well that if a pilot decides to actively control a dutch roll using aileron then unless he properly adapts his internal transfer function to match the open loop dynamics of the airframe there is a risk that at some value of pilot gain the root locus of the closed loop system might cross over into the negative damping region. [That piece of jargon ridden technological gobbledygook translates as "If the pilot tries to chase the dutch roll and gets his timing wrong he could end up in a PIO or APC situation"]
From what you have written this might have been the case on that Learjet?
What we need is a new point of view that does not exist in our regulations of certification concerning RESONANCE. It could be builded on Machinbird's post and enhanced from his first text and his experience of PIO and high level flight experience. His post with Bode figure with numbers is a good beginning of what we have to think about the dynamic system.
In any case what is missing in our certification and knowledge is a quantified reference to dynamics of the transient parts of the plane's oscillation, Pio and other APC.
In any case what is missing in our certification and knowledge is a quantified reference to dynamics of the transient parts of the plane's oscillation, Pio and other APC.
§ 25.181 Dynamic stability.
(b) Any combined lateral-directional oscillations (“Dutch roll”) occurring between 1.13 VSR and maximum allowable speed appropriate to the configuration of the airplane must be positively damped with controls free, and must be controllable with normal use of the primary controls without requiring exceptional pilot skill.
(b) Any combined lateral-directional oscillations (“Dutch roll”) occurring between 1.13 VSR and maximum allowable speed appropriate to the configuration of the airplane must be positively damped with controls free, and must be controllable with normal use of the primary controls without requiring exceptional pilot skill.
§ 23.181 Dynamic stability.
(b) Any combined lateral-directional oscillations (Dutch roll) occurring between the stalling speed and the maximum allowable speed (VFE , VLE , VN0 , VFC /MFC ) appropriate to the configuration of the airplane with the primary controls in both free and fixed position, must be damped to 1⁄10 amplitude in:
(1) Seven (7) cycles below 18,000 feet and
(2) Thirteen (13) cycles from 18,000 feet to the certified maximum altitude.
(b) Any combined lateral-directional oscillations (Dutch roll) occurring between the stalling speed and the maximum allowable speed (VFE , VLE , VN0 , VFC /MFC ) appropriate to the configuration of the airplane with the primary controls in both free and fixed position, must be damped to 1⁄10 amplitude in:
(1) Seven (7) cycles below 18,000 feet and
(2) Thirteen (13) cycles from 18,000 feet to the certified maximum altitude.
Moderator
Speaking more generally about commercially sensitive information,
Which, I understand is why the Brits, doing the right thing with respect to the knowledge gained with the Comet problems ... basically were dudded by the 707 in short order ...
Which, I understand is why the Brits, doing the right thing with respect to the knowledge gained with the Comet problems ... basically were dudded by the 707 in short order ...
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Quote:
Originally Posted by Machinbird
The problem is that the force and travel required to activate the rudder to its limits were minimal, and thus it was easy to excite a yaw oscillation by relatively small repetitive rudder inputs.
If you will remember, it only took about 30 lbs of force to reach the limit at that speed-that isn't much at all.
He was attempting to get the rudder moved as quickly as possible and was trying to help it along.
Or perhaps he was just spooked by the extreme yaw.
Assuming they only have rudder position indications on the FDR and not force indications, the 140 lb estimate would come from rudder rate acceleration tests.
Originally Posted by Machinbird
The problem is that the force and travel required to activate the rudder to its limits were minimal, and thus it was easy to excite a yaw oscillation by relatively small repetitive rudder inputs.
Originally Posted by Clandestino
Makes me wonder if it was so easy, why did the unlucky F/O bother with exerting 140 lbs push?
He was attempting to get the rudder moved as quickly as possible and was trying to help it along
. Or perhaps he was just spooked by the extreme yaw.
Assuming they only have rudder position indications on the FDR and not force indications, the 140 lb estimate would come from rudder rate acceleration tests.
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While it's true that the R&D "sharing" with the US in the postwar years skewed decidedly one way - it's also true that due to political and business machinations it was as much the fault of the parties on this side of the Atlantic as anyone. Of course the main issue with the mass-production side of things was difference in size of the potential civil airliner market following the war. A populace undergoing an austerity drive was never going to be able to afford airline travel easily, whereas the postwar growth of the US economy - along with the sheer size of the country - meant that air travel was not only within the reach of more of the population, but became a practical necessity for many.
Anyways - an interesting subject, but off-topic. So I'll leave it there for now.
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OK, flarepilot. Here is what a very highly experience aviator (and Saberliner 40 pilot) has to say re your Sabre 40 assertions.
Okay, I have to call BS on this statement:
Quote by flarepilot "Flying it very high by hand was the most demanding flying I've ever idone, but I got the hang of it."
All Sabres were a delight to fly by hand no matter the altitude. So he is one of the worse pilots that has ever flown one, or he is a liar. The only types aircraft I have flown that may have been easier to fly by hand regardless of the altitude, is the Falcon 50/900 series and the Lockheed Jetstar.
Also, the military version of the Sabre 40, the T-39 had no auto-pilot* and were flown single pilot by the US Air Force. Hardly something that they would allow in the "demandingy flying" aircraft that someone had ever flown. One other thing, the wing on the Sabreliners was essentially the same wing as on the F-86 and F-100, both of which had no auto-pilot and were obviously were single pilot aircraft.
So at this point, I believe that the question about the aileron restriction is immaterial. As with the statement of his that you posted, goes a long way of proving this guy a 'Walt'.
Okay, I have to call BS on this statement:
Quote by flarepilot "Flying it very high by hand was the most demanding flying I've ever idone, but I got the hang of it."
All Sabres were a delight to fly by hand no matter the altitude. So he is one of the worse pilots that has ever flown one, or he is a liar. The only types aircraft I have flown that may have been easier to fly by hand regardless of the altitude, is the Falcon 50/900 series and the Lockheed Jetstar.
Also, the military version of the Sabre 40, the T-39 had no auto-pilot* and were flown single pilot by the US Air Force. Hardly something that they would allow in the "demandingy flying" aircraft that someone had ever flown. One other thing, the wing on the Sabreliners was essentially the same wing as on the F-86 and F-100, both of which had no auto-pilot and were obviously were single pilot aircraft.
So at this point, I believe that the question about the aileron restriction is immaterial. As with the statement of his that you posted, goes a long way of proving this guy a 'Walt'.
With 500 hours in the Hun and about the same in the Sabre 65, I'd agree that both are pleasant to handfly at any altitude. The Hun had its moments, but that comes with the environment of any TAC fighter. No such restriction in my memory, but who would use 50% of control authority at high altitude/high Mach anyway?
Last edited by galaxy flyer; 9th Oct 2013 at 16:56.
Originally Posted by Flarepilot
the industry changed its way of handling DE ICING and ANTI ICING over the F28. Sorry, you must have been chewing on something else.
Originally Posted by Machinbird
If you will remember, it only took about 30 lbs of force to reach the limit at that speed-that isn't much at all.
Last edited by Clandestino; 9th Oct 2013 at 17:45.
Quote:
Originally Posted by tdracer
I know things that I'm not allowed to make public. Oftentimes it's considered [X] proprietary/sensitive, in the case of air safety investigations
Could these things kill again?
Originally Posted by tdracer
I know things that I'm not allowed to make public. Oftentimes it's considered [X] proprietary/sensitive, in the case of air safety investigations
Could these things kill again?
). There can be potential liability concerns - releasing partial or out of context info could result in slander and lawsuits (I've been the target of a slander lawsuit - it's no fun even when you can document what you said was accurate). So there is a process to release information in a controlled manner via the investigating agency (e.g. NTSB in the US). If there is something that poses an imminent threat to other aircraft, then it's the responsibility of the investigating agency to make that information public so that appropriate measures can be taken. After the 787 Heathrow fire, many on here where complaining that Boeing wasn't forthcoming with information - short answer is the manufacturer is effectively gagged during the investigation - ALL public information is supposed to come from the investigating agency. For Boeing to release information could have gotten them in big trouble.
I was involved in the investigation of the BA 777 that 'landed short' at Heathrow (I was in a Boeing Safety Review Board meeting on an unrelated subject when a co-working showed me a picture of the crashed 777 on his laptop and said 'just happened!'
). Anyway, within about a week we had a pretty good idea that ice had blocked the fuel/oil heat exchanger. But it took a couple months to validate that theory (rig testing and the such). If we'd released information implicating the Trent fuel system, and that turned out to be wrong - there would have been hell to pay 
. The good news is that the designers were able to work on the fix even before the cause had been firmly established.Some of you certainly remember the fiasco after the Chicago DC-10 engine separation and crash - when everyone though it was because of a broken bolt instead of damaged structure?
It's certainly good to get information out quickly, but you need to make sure it's the correct information.
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Owain,
I have really nothing against Davies formulation ! Thank you for quoting it here. The only thing I see in my method (perhaps Davies did it for himself but did not express it here) is to get quantification instead of global words which can be misunderstood by pilots who revendicate to be stupid...
My bold show the words I did quantify :
I am seeing too that Davies's method is a step by step method effectively as you said it it can be seen as on open loop action, mine is continuous in the closed loop.
When Davies says "watch the rolling motion", I do the same but quantifying. Despite Davies's lack of precision we both know that we must read in the beginning of the transient response the clue to start the correction before the transient part is finished. He does not suggest to the pilot to start asap the correction, but when he feel "good and ready". But I understand that prudent formulation and choice of Davies, so long as pilot don't want to reckon some precisions... :
Exactly ! Probably my teacher had a sudden thought to that risk at the moment he was speaking of root locus and decided him to say his sentence.
It seems that Chris's method on B727 is Davies's one like but less developped in the formulation I found in the Yaw damper thread ?
Why did Learjet not adopt Davies's method and stay wrong with the rudder use, and reversal use, and brutality use ?
Stopping the bad divergent oscillation is not all : probably your aircraft wants to play it again ! that divergence had a cause, and watching the motion quantatively helps to fly safe at home avoiding a new divergence with your jammed yaw damper...
The final object of certification is to do the aircraft safe for the wanted use. Today we have to increase air safety despite crashes statistics are getting better. All the crashes which can be avoided have to get progressively suppressed. Changing certification rules can perhaps help, and if it should help why not try ? Perhaps it could improve the speed of information from engineers to pilots ?
Writing operational rules may sometimes be included in certification. I remember when Concorde has been built some people said the bang should not be listen on the continent, so it was not possible to certify it. But thinking that the sound energy was decreasing with distance finaly it could be certified if respecting operational rules like not focalising turns, and respecting some distance of the coasts, and determining quantitatively point at which Concorde should start acceleration to M 1.
Originally Posted by Owain Glyndwr
Well not entirely d'accord
My bold show the words I did quantify :
Originally Posted by Davies
The control of divergent dutch roll is not difficult so long as it is handled properly. Let us assume that your aeroplane develops a diverging dutch roll. The first thing to do is nothing - repeat nothing. Too many pilots have grabbed the aeroplane in a rush, done the wrong thing and made matters a lot worse. Don't worry about a few seconds delay because it won't get much worse in this time. Just watch the rolling motion and get the pattern fixed in your mind. Then, when you are good and ready, give one firm but gentle correction on the aileron control against the upcoming wing. Don't hold it on too long - just in and out - or you will spoil the effect. You have then, in one smooth controlled action, killed the biggest part of the roll. You will be left with a residual wiggle, which you can take out, still on ailerons alone, in your own time.
Don't attempt to correct the manoeuvre with rudder; as explained, the yaw is often suppressed and it is difficult to work out which way to apply the rudder at what particular moment and there is a good chance that the wrong rudder will be applied which will aggravate things very quickly. It is not difficult, however to apply the correct aileron control. Further, don't attempt to squash the dutch roll flat in one fell swoop but be content with taking out a big bite first time then sorting out the remainder next time
Don't attempt to correct the manoeuvre with rudder; as explained, the yaw is often suppressed and it is difficult to work out which way to apply the rudder at what particular moment and there is a good chance that the wrong rudder will be applied which will aggravate things very quickly. It is not difficult, however to apply the correct aileron control. Further, don't attempt to squash the dutch roll flat in one fell swoop but be content with taking out a big bite first time then sorting out the remainder next time
When Davies says "watch the rolling motion", I do the same but quantifying. Despite Davies's lack of precision we both know that we must read in the beginning of the transient response the clue to start the correction before the transient part is finished. He does not suggest to the pilot to start asap the correction, but when he feel "good and ready". But I understand that prudent formulation and choice of Davies, so long as pilot don't want to reckon some precisions... :
I know very well that if a pilot decides to actively control a dutch roll using aileron then unless he properly adapts his internal transfer function to match the open loop dynamics of the airframe there is a risk that at some value of pilot gain the root locus of the closed loop system might cross over into the negative damping region.
It seems that Chris's method on B727 is Davies's one like but less developped in the formulation I found in the Yaw damper thread ?
Why did Learjet not adopt Davies's method and stay wrong with the rudder use, and reversal use, and brutality use ?
Stopping the bad divergent oscillation is not all : probably your aircraft wants to play it again ! that divergence had a cause, and watching the motion quantatively helps to fly safe at home avoiding a new divergence with your jammed yaw damper...
Here I do disagree with you. The object of certification is to avoid any resonance not devise rules to tame it
Writing operational rules may sometimes be included in certification. I remember when Concorde has been built some people said the bang should not be listen on the continent, so it was not possible to certify it. But thinking that the sound energy was decreasing with distance finaly it could be certified if respecting operational rules like not focalising turns, and respecting some distance of the coasts, and determining quantitatively point at which Concorde should start acceleration to M 1.
Last edited by roulishollandais; 14th Oct 2013 at 17:10.
The KAVP T-39 accident with Gen O'Malley and his wife had nothing to do with Sabre high altitude handling and everything with no anti-skid installed and risk analysis of the airport. Can't speak to the 40, but the 65 was docile everywhere. Bob Hoover, who did shows with it would agree.
The T-39s were typically flown by first assignment pilots out of UPT who had a better record in it than in the Lears that followed.
The T-39s were typically flown by first assignment pilots out of UPT who had a better record in it than in the Lears that followed.
Last edited by galaxy flyer; 9th Oct 2013 at 22:34.
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Clandestine, I am not as worried about Airbus systems as much as junior pilots with no experience never geting any real hands on flying experience. Some day they will need real hands on flying experience or it will a be repeat of AF 447. Our generations had to handfly and welcomed the challenge. I don't like where we are headed. Many others here don't either. None of us old school pilots were too concerned if everything went south because it was just an inconvenience, now it is turning into an emergency.
