FAO Messi of Aeroengineering
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- flyboy2548m
- Posts: 4395
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- Location: Ormond Beach, FL
FAO Messi of Aeroengineering
Seriously, what's with you and the Phugoid? I'm genuinely curious.
"Lav sinks on 737 Max are too small"
-TeeVee, one of America's finest legal minds.
-TeeVee, one of America's finest legal minds.
Re: FAO Messi of Aeroengineering
We think you guys should know about them and the UA-DC-6.7-Iowa-City-No-Hydraulic dudes apparently did not.Seriously, what's with you and the Phugoid? I'm genuinely curious.
Important note: It was roughly 15 years ago I learned the TERM phugoid.
BUT LONG BEFORE THAT...
as I kid, I played with balsa wood airplanes...if I threw them too hard they climbed, if I threw them too slow they dove and sometimes they'd climb and dive in cycles...
Then I read Wolfgang-Stick and Rudder and the concept of the aircraft "seeking it's trimmed speed"...yeah, makes sense.
Jump to my VERY VERY first flying lesson...where I learned these things:
-You do a pretakeoff checklist and engine run up and check the two magneto systems (and etc.)
-You need right rudder to counteract torque/p-factor/slip-stream-VS effects
-You do not HOLD aileron to turn (you establish a bank and then neutralize things)
-Relentless pull ups cause stalls and that is sort of a bad thing.
-The plane is climbing...now it's descenting...WTF...oh wow- that's that "seeking it's trimmed speed behavior...just like the balsa-wood models.
-To STOP the speed seeking-climbing-descending, put the nose at a fixed level below the horizon...(maybe like a fist's worth)
Some years later, I'm reading some business about FBW and how they got the plane to finally do a phugoid.
Phugoid? WTF is a Phugoid? (later I learn it's a $20 aeroengineering term for those trim-speed-seeking cycles).
Bottom line: We just kind a think it's one of those super basic fundamental things...I don't give a rat if it goes by the fancy name or not. I do sorta think any self-respecting airline pilot might know that the behavior exists and that it takes at least a little management effort by the pilot or autopilot or the Airbus FBW computer. (Plus, you never know when you'll lose all hydraulics and have use some OTHER method to deal with phugoid dip-and-climb-trim-speed-seeking behavior)
That is all.
***BUT***
It really that unreasonable to feel that way?
Commercial Pilot, Vandelay Industries, Inc., Plant Nutrient Division.
Re: FAO Messi of Aeroengineering
What 3WE said.
I can call it long-period longitudinal oscillatory mode of motion, if you prefer.
I can call it long-period longitudinal oscillatory mode of motion, if you prefer.
- flyboy2548m
- Posts: 4395
- Joined: Sat Feb 02, 2008 12:32 am
- Location: Ormond Beach, FL
Re: FAO Messi of Aeroengineering
What?We think you guys should know about them and the UA-DC-6.7-Iowa-City-No-Hydraulic dudes apparently did not.Seriously, what's with you and the Phugoid? I'm genuinely curious.
Important note: It was roughly 15 years ago I learned the TERM phugoid.
BUT LONG BEFORE THAT...
as I kid, I played with balsa wood airplanes...if I threw them too hard they climbed, if I threw them too slow they dove and sometimes they'd climb and dive in cycles...
Then I read Wolfgang-Stick and Rudder and the concept of the aircraft "seeking it's trimmed speed"...yeah, makes sense.
Jump to my VERY VERY first flying lesson...where I learned these things:
-You do a pretakeoff checklist and engine run up and check the two magneto systems (and etc.)
-You need right rudder to counteract torque/p-factor/slip-stream-VS effects
-You do not HOLD aileron to turn (you establish a bank and then neutralize things)
-Relentless pull ups cause stalls and that is sort of a bad thing.
-The plane is climbing...now it's descenting...WTF...oh wow- that's that "seeking it's trimmed speed behavior...just like the balsa-wood models.
-To STOP the speed seeking-climbing-descending, put the nose at a fixed level below the horizon...(maybe like a fist's worth)
Some years later, I'm reading some business about FBW and how they got the plane to finally do a phugoid.
Phugoid? WTF is a Phugoid? (later I learn it's a $20 aeroengineering term for those trim-speed-seeking cycles).
Bottom line: We just kind a think it's one of those super basic fundamental things...I don't give a rat if it goes by the fancy name or not. I do sorta think any self-respecting airline pilot might know that the behavior exists and that it takes at least a little management effort by the pilot or autopilot or the Airbus FBW computer. (Plus, you never know when you'll lose all hydraulics and have use some OTHER method to deal with phugoid dip-and-climb-trim-speed-seeking behavior)
That is all.
***BUT***
It really that unreasonable to feel that way?
"Lav sinks on 737 Max are too small"
-TeeVee, one of America's finest legal minds.
-TeeVee, one of America's finest legal minds.
Re: FAO Messi of Aeroengineering
Humour appreciated and no, I am not planning to replace Richard Collins at Aviation Typists.What?
If you truly don't understand, I am concerned you are breathing too much of the combustion by-products of that nasty turbine oil additive.
My post has a strong introductory sentence and a nice bold bottom line.
Amazingly, sometimes we amateurs know one or two things...so much so that we even make wild ass guesses that RTO autobraking includes an anti-skid system.
Returning to realm of humour (while also being 100% true), At age 13, I got a "fly-by string" / "gas" powered model airplane.
On the maiden voyage, the plane was doing significant and worsening climb and dive phugoids and I was totally behind the airplane and not really understanding what was going on...If I had only anticipated some nose-down input shortly before the plane stopped diving...
...flew straight over my head, and on the way down, I didn't have time to pull up and hit the hard concrete playground in a 45-degree dive.
The propeller and it's spinner and some non-essential parts of the plane did died.
Bottom line: This crap is important.
Commercial Pilot, Vandelay Industries, Inc., Plant Nutrient Division.
Here, I dumbed it down.
Most airplanes have a behavior of trying to "seek out" a trimmed speed and attitude...Without inputs, planes typically display a "dive and climb" behavior- which Gabriel and friends call a Phugoid.
We think you guys should know about Phugoids and the UA-DC-6.7-Iowa-City-No-Hydraulic dudes apparently did not.
It's a tad disturbing that three flight crew possibly did not understand what was going on with the crippled DC-10.
Bottom line: We just kind a think it's one of those super basic fundamental things...3BS does not give a rat if it goes by the fancy name or not. I do sorta think any self-respecting airline pilot might know that the behavior exists and that it takes at least a little management effort by the pilot or autopilot or the Airbus FBW computer.
(Plus, you never know when you'll lose all hydraulics and have use some OTHER method to deal with phugoid dip-and-climb-trim-speed-seeking behavior)
Commercial Pilot, Vandelay Industries, Inc., Plant Nutrient Division.
- flyboy2548m
- Posts: 4395
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- Location: Ormond Beach, FL
Re: FAO Messi of Aeroengineering
I'm getting the sense you'll be milking that RTO business for a while...much like Gabby milks the phugoid...
Amazingly, sometimes we amateurs know one or two things...so much so that we even make wild ass guesses that RTO autobraking includes an anti-skid system.
"Lav sinks on 737 Max are too small"
-TeeVee, one of America's finest legal minds.
-TeeVee, one of America's finest legal minds.
Re: FAO Messi of Aeroengineering
1. Fixed.I'm getting the sense you'll be milking that RTO business for a really long time much like relentless pull ups and storm penetration and more...much like Gabby milks the phugoid...and Flyboy milks the "What?"
2. I'm getting the sense that bears crap in the woods.
Commercial Pilot, Vandelay Industries, Inc., Plant Nutrient Division.
- flyboy2548m
- Posts: 4395
- Joined: Sat Feb 02, 2008 12:32 am
- Location: Ormond Beach, FL
Re: FAO Messi of Aeroengineering
Well, I could have just told you and Gabby to go phug yourselves, but that would be too easy. I guess what I'm wondering is what you (plural, of course) expect me to do about this phugoid. If a large aircraft experiences enough failures to where the phugoid is much of a factor, it's probably going to be the least of my problems.1. Fixed.I'm getting the sense you'll be milking that RTO business for a really long time much like relentless pull ups and storm penetration and more...much like Gabby milks the phugoid...and Flyboy milks the "What?"
2. I'm getting the sense that bears crap in the woods.
"Lav sinks on 737 Max are too small"
-TeeVee, one of America's finest legal minds.
-TeeVee, one of America's finest legal minds.
Re: FAO Messi of Aeroengineering
On the contrary. I agree that it is super unlikely that you will ever need it, but if a large aircraft experiences enough failures to where the phugoid is much of a factor, managing it is probably going to be key to the outcome, as it was in UA at Sioux City and DHL at Baghdad.Well, I could have just told you and Gabby to go phug yourselves, but that would be too easy. I guess what I'm wondering is what you (plural, of course) expect me to do about this phugoid. If a large aircraft experiences enough failures to where the phugoid is much of a factor, it's probably going to be the least of my problems.
Anyway, I am not even proposing training ATP pilots in how to manage this oscillatory motion with no elevator or trim control (because you do manage it all the time with elevator and trim, ok, I stand corrected, not in an Airbus in normal low, the FBW does that for you even in manual flight).
- flyboy2548m
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- Joined: Sat Feb 02, 2008 12:32 am
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Re: FAO Messi of Aeroengineering
I thought you said Sioux City was a failure, and that had they only not phugged up their phugoid so bad, they would have landed with no fatalities. Or does that mean something else in Argentine?On the contrary. I agree that it is super unlikely that you will ever need it, but if a large aircraft experiences enough failures to where the phugoid is much of a factor, managing it is probably going to be key to the outcome, as it was in UA at Sioux City and DHL at Baghdad.
"Lav sinks on 737 Max are too small"
-TeeVee, one of America's finest legal minds.
-TeeVee, one of America's finest legal minds.
Re: FAO Messi of Aeroengineering
I am not buying your act that maybe the Domestic Super Aviation Encyclopedia of the Millennium does not give a flying phugoid about basic, fundamental aircraft behavior.*** I guess what I'm wondering is what you (plural, of course) expect me to do about this phugoid.*** If a large aircraft experiences enough failures to where the phugoid is much of a factor, it's probably going to be the least of my problems.
As to what I want you to do about it?
I seem to recall two things about you:
1) You hand fly a fair bit.
2) You spent a significant amount of time operating a CRJ with no auto throttles.
If that is true, then every time you initiated a climb or descent or leveled or sped up or slowed down or encountered a wind shear, (and were hand flying) you managed phugoid behavior. (Given the lack of auto throttles, I'm guessing you often managed phugoid behavior even when using autopilot.)
AND, I'm thinking we also have some Embraer-Other-Than-Airbus time.
Seems to me Flyboy spent a decent amount of his career managing phugoid behavior, and maybe even managed phugoids while doing tail dragger training with ITS.
So you are an Airbus Jock, and HAL handles phugoid behavior...yeah, we get that- but I'm still thinking that among your incredible first-world, intensive training regime, some of that time is devoted to how stuff works- all sorts of stuff including basic PPL aereodienamicks.
Does Airbus training really emphasize that you purge your mind that 'excess' speed will make the aircraft 'want' to climb...and 'deficient' speed will make it 'want' to descend? That pulling up will make the plane 'want' to lose speed, and pushing over will make the plane 'want' to gain speed?
Footnote: We do not expect you to get in a sim and get a phugoid going and manage it without working the elevators or trim. We just know how basic phuging aerodynamics' works.
Commercial Pilot, Vandelay Industries, Inc., Plant Nutrient Division.
- flyboy2548m
- Posts: 4395
- Joined: Sat Feb 02, 2008 12:32 am
- Location: Ormond Beach, FL
Re: FAO Messi of Aeroengineering
I think you're missing the point. I was talking more about how I'm supposed to not phug up the phugoid when:I am not buying your act that maybe the Domestic Super Aviation Encyclopedia of the Millennium does not give a flying phugoid about basic fundamental aircraft behavior.
As to what I want you to do about it?
I seem to recall two things about you:
1) You hand fly a fair bit.
2) You spent a significant amount of time operating a CRJ with no auto throttles.
If that is true, then every time you initiated a climb or descent or leveled or sped up or slowed down or encountered a wind shear, (and were hand flying) you managed phugoid behavior. (Given the lack of auto throttles, I'm guessing you often managed phugoid behavior even when using autopilot.)
1. I have no functioning control surfaces;
2. I am down an engine, and the ONLY control I have are the remaining engines, thanks be to Quetzalcoatl they're underslung.
Apparently Gabby is under the impression that getting that godforsaken DC-10 anywhere near a runway at all was no big deal. If only they weren't such phugups, they could have saved everybody. Now, I think he is, to use his own words, delusional, but I'm not an amateur, so what do I know?
"Lav sinks on 737 Max are too small"
-TeeVee, one of America's finest legal minds.
-TeeVee, one of America's finest legal minds.
Re: FAO Messi of Aeroengineering
(And this post is also relevant to the post you just snuck in.)***I thought you said Sioux City was a failure, and that had they only not phugged up their phugoid so bad, they would have landed with no fatalities.***
Don't go black and white on us.
If the dudes really said, "we didn't know about the dive and dip behavior of an airplane", one can speculate that maybe they could have practiced a little bit on the way to Sioux City and maybe managed it to a smoother landing.
Indeed- "maybe" is a key word.
It's also a tad shocking if they really, actually said, "I didn't know that airplanes had dip and dive speed-attitude hunting behavior"...(Did they say that or did they say they didn't know the $20 Ph-bomb TERM? That is two different things.)
We also need to avoid sounding as though the pilots sucked and that we parlour experts would have greased the landing and not crashed and burned until we ran off the runway. We don't mean to say that- but indeed, sometimes it sounds like we do.
Accept our apologies for playing "what if"and for any implication that Sioux City was an easy phix.
Commercial Pilot, Vandelay Industries, Inc., Plant Nutrient Division.
- flyboy2548m
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- Joined: Sat Feb 02, 2008 12:32 am
- Location: Ormond Beach, FL
Re: FAO Messi of Aeroengineering
Some think that it was such an easy phix that even a Tomahawk phlyer could have managed it.Accept our apologies for playing "what if"and for any implication that Sioux City was an easy phix.
"Lav sinks on 737 Max are too small"
-TeeVee, one of America's finest legal minds.
-TeeVee, one of America's finest legal minds.
Re: FAO Messi of Aeroengineering
I didn't say it was a failure. I did say that had they managed the phugoid better the plane could have been landed with no fatalities. Sorry if you don;t like that, but that's more a fact than an opinion.I thought you said Sioux City was a failure, and that had they only not phugged up their phugoid so bad, they would have landed with no fatalities. Or does that mean something else in Argentine?On the contrary. I agree that it is super unlikely that you will ever need it, but if a large aircraft experiences enough failures to where the phugoid is much of a factor, managing it is probably going to be key to the outcome, as it was in UA at Sioux City and DHL at Baghdad.
But the flip coin of that is that they did manage the phugoid (even if not was well as they could have had they known how to do i)t, and that saved most lives on that plane. Had they not managed it as well as they did, they could be all dead.
Summary, when it comes to landing a big plane with no elevator or trim control, how well/bad you manage the phugoid is key to how good/bad the outcome is.
And the key to manage the phugoid are:
1- Difference between your trim speed and your actual speed defines the pitch rate. So, for example, if you are flying straight and level with no oscillations (then you are flying at your trim speed) and want to start a descent with no oscillations, you can reduce the thrust to reduce the speed by say 10 knots, then keep adjusting the thrust to keep that -10 kts delta, and when you reach your desired pitch you increase thrust to accelerate back to your trim speed and then reduce/adjust thrust to keep the trim speed. As another example, to flare, add thrust to increase the speed.
2- How to find the trim speed in the first place? Watch the initial oscillations (before you stabilize the flight). The trim speed is where the pitch rate is reversed (i.e. the plane pitches up, stops and the pitches down. The point where it stops is the trim speed).
These 2 points are the most important ones, and let you fly a plane and transition from between climbs, level flight, and descents, without phugoid oscillations. But there is more.
3- You cannot control your trim speed. i.e you cannot decide the speed you will use to land. You can only fly stably at the trim speed.
4- However, there are things that affect your trim speed, and you can use some of them in your favor (others not so much), these things are:
a- CG. If you can shift weight (persons, fuel, etc...), the more aft the CG the slower the trim speed.
b- Thrust, especially with underslung engines, affects trim speed since it creates a pitching moment. The more thrust the slower the trim speed. So, for example, a shallower approach requiring more thrust will be slower than a steeper approach requiring less thrust.
c- Extending the landing gear creates drag below the CG, which adds pitch-don moment and hence increases the trim speed. While you will require more thrust to compensate the extra drag and this creates a nose-up pitching moment (with undesrlung engines) and hence a slower trim
speed, the drag line of the landing gear is below the thrust line so the overall impact will be a faster trim speed.
d- Turns invariable increase your trim speed. So keep them shallow and bank slowly, slowly increasing your speed as your bank angle increases.
These things can be practiced and mastered in a simulator. It is not difficult but it will take hours of practice, as one needs to learn a totally different way to fly. And, unlike stick-and-rudder, it is quite type specific for the effect of thrust in trim speed (the 737 will have a quite different reaction compared with the MD-80). Worth it? I don't know. Crashes happen much more often for other pilot screw-ups than for not knowing how to manage phugoids. So if sim time is scarce, probably learning to master the phugoid is not the best use of it.
Re: FAO Messi of Aeroengineering
Well, actually a good management of the phugoid involves using the plane dynamics in your favor so the phugoid oscillations don't happen.I think you're missing the point. I was talking more about how I'm supposed to not phug up the phugoid when:
1. I have no functioning control surfaces;
2. I am down an engine, and the ONLY control I have are the remaining engines, thanks be to Quetzalcoatl they're underslung.
Having undeslung engines is not a central part of it, and the fact that you (sort of) said it is shows your lack of understanding.
That gives you more pitch authority but also changes your trim speed every time you change the thrust. It is much easier to manage the phugoid with central thrust where the trim speed is not noticeably affected by changes in thrust (i.e. NOT with undesrlung engines).
You ask how? That is in my previous post.
It was a big deal and a great work, GIVEN THAT THEY DIDN'T KNOW HOW TO MANAGE THE PHUGOID AND HAD TO LEARN IT ON THE FLY.Apparently Gabby is under the impression that getting that godforsaken DC-10 anywhere near a runway at all was no big deal.
Not as much as I do about phugoid, evidently. But don't worry, that's understandable. Pilots don't learn the non-linear 2nd degree differential equation of longitudinal motion (or should I say equations, they are three entangled equations with three independent variables), subject about which I wrote a sort of thesis that was later used as bibliographical material in the Aerodynamics II class in the university. Nor they need to. Phugoid can be learned with practice even without understanding it (as flying), and it can be understood by understanding the concepts behind it which doesn't require learning said equation. But learning said equations lead to understanding phugoid, that is how I do it and you don't.Now, I think he is, to use his own words, delusional, but I'm not an amateur, so what do I know?
I am not delusional. Successfully managing phugoid to fly a plane with no elevator, no trim, and no phugoid oscillations is not just theoretically possible. It has been tested. All pilots fail when they try before learning how to do it, and that's why the job of the UA flight crew, and especially the pax-pilot, was great, given what they knew.
Last edited by Gabriel on Sun Jul 15, 2018 5:10 am, edited 1 time in total.
Re: FAO Messi of Aeroengineering
Double post
Last edited by Gabriel on Sun Jul 15, 2018 5:04 am, edited 1 time in total.
Re: FAO Messi of Aeroengineering
Triple post
Last edited by Gabriel on Sun Jul 15, 2018 5:04 am, edited 1 time in total.
Re: FAO Messi of Aeroengineering
Quadruple post
- flyboy2548m
- Posts: 4395
- Joined: Sat Feb 02, 2008 12:32 am
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Re: FAO Messi of Aeroengineering
Well...it's not like this is the first time you made up your own "facts"...
I didn't say it was a failure. I did say that had they managed the phugoid better the plane could have been landed with no fatalities. Sorry if you don;t like that, but that's more a fact than an opinion.
"Lav sinks on 737 Max are too small"
-TeeVee, one of America's finest legal minds.
-TeeVee, one of America's finest legal minds.
- flyboy2548m
- Posts: 4395
- Joined: Sat Feb 02, 2008 12:32 am
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Re: FAO Messi of Aeroengineering
Your phugging medal is on its way.
Not as much as I do about phugoid, evidently. But
"Lav sinks on 737 Max are too small"
-TeeVee, one of America's finest legal minds.
-TeeVee, one of America's finest legal minds.
Re: FAO Messi of Aeroengineering
So Gabe, you've got this tone that if the Sioux City guys had some sim time and just done 1, 2, 3, and 4 there'd have been no crash.Quote=Gabe
And the key to manage the phugoid are:
1-
2-
These 2 points are the most important ones
But there is more.
3-
4-
a-
b-
So, for example
c-
d-
BUT
1. They had more problems than no controls. I think there were several minutes where
A. Staying right side up was a challenge
and
B. Having directional control was a challenge
and
C. Doing things (turns, initiating descents, dropping the gear) often had them nearly losing control
AND
2. It's a big huge slow responding plane with big huge slow responding engines...
It was a hell of an accomplishment to guide it to the runway...
Now-if they truly had no concept of trim-speed-attitude chasing (which I'm beginning to doubt) is there a scenario where a different power reduction and power 'burst' might have resulted in a 'gentle' touchdown...
I dunno- it's a really big "if".
As they say- "If a frog had wings, and if it knew how to manage phugoids, maybe it wouldn't bump its ass when it hops."
Last edited by 3WE on Sun Jul 15, 2018 1:00 pm, edited 2 times in total.
Commercial Pilot, Vandelay Industries, Inc., Plant Nutrient Division.
Re: FAO Messi of Aeroengineering
Part II:
Take all of the above and ask if it's worth the time to train folks in Gabe's 4-part procedure and let them get a feel in the sim for how it works on a healthy, big ass aeroplanie...with Evan bitching that more time is needed on how to operate autopilots in FLCH and UAS and dual EALCAS failures and avoiding somatographic illusions at the end of 14 hour days with phugged up sleep cycles...
I begin to see flyboy's side that it's not the best use of time.
Yeah, sure, the next time a plane loses all hydraulics, it would be nice to have, but I'm still wondering how the Sioux City bunch was going to stay on the runway and stop?
Take all of the above and ask if it's worth the time to train folks in Gabe's 4-part procedure and let them get a feel in the sim for how it works on a healthy, big ass aeroplanie...with Evan bitching that more time is needed on how to operate autopilots in FLCH and UAS and dual EALCAS failures and avoiding somatographic illusions at the end of 14 hour days with phugged up sleep cycles...
I begin to see flyboy's side that it's not the best use of time.
Yeah, sure, the next time a plane loses all hydraulics, it would be nice to have, but I'm still wondering how the Sioux City bunch was going to stay on the runway and stop?
Last edited by 3WE on Sun Jul 15, 2018 1:05 pm, edited 2 times in total.
Commercial Pilot, Vandelay Industries, Inc., Plant Nutrient Division.
- flyboy2548m
- Posts: 4395
- Joined: Sat Feb 02, 2008 12:32 am
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Re: FAO Messi of Aeroengineering
It's not just a tone, it's apparently a fact, he wrote a phugging thesis on it.
So Gabe, you've got this tone that if the Sioux City guys had some sim time and just done 1, 2, 3, and 4 there'd have been no crash.
Last edited by flyboy2548m on Sun Jul 15, 2018 1:03 pm, edited 1 time in total.
"Lav sinks on 737 Max are too small"
-TeeVee, one of America's finest legal minds.
-TeeVee, one of America's finest legal minds.
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