Problems in a commercial flight

writes:

Yes, they can.

No, they cannot, except under ideal conditions, and sometimes not even then.

But what do I know, I only fly tiny planes.

My thoughts exactly.

--
Transpose mxsmanic and gmail to reach me by e-mail.

I am the original poster, not MXSMANIC and since I have blocked his posts, some of the thread might be as well.

We were cruising and the flames were well behind the engine, sort of like a small afterburner effect. We flew on without incident. I always wondered what the difference between "running rich" and ENGINE FIRE! might be.

On another AJ flight, the passenger beside me left his seat about the same time the FA was giving her speil about the life vest under the seat. I felt under my seat and found only an empty pocket. I rang the FA and told her that I had no life vest. She said "No problem" and pulled the one out from the temporarily vacant seat next to mine and put it under my seat!





Google Plex wrote:

MXSMANIC wrote:



I was flying in an Air Jamaica jet many years ago and while cruising
noticed large reddish flames from the exhaust of the Rolls Royce engine.
How "normal" would that be?


It depends on the exact conditions. Were you cruising? Climbing?
Descending? What altitude? How did the engine sound? How long did the
flames last, and what did they look like, exactly?



Under which of these conditions, exactly, would large reddish flames from the
exhaust of a Rolls Royce engine be 'normal'?




Normally visible flames don't extend beyond the engine, although if you look
directly into the exhaust of a jet engine you may well be able to see glowing
internal parts.



That's rather difficult to do from inside the plane.




High-performance engines may glow externally as well. And of
course afterburners can produce long flames that extend well beyond the
engine. And so on.



Does Air Jamaica use afterburners?




--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P

On Mar 14, 3:59 pm, Dave wrote:
Soooo..

How come he (MX) was able to give a rather complete and correct
answer to the poster's question?

Care to give it a try?

Dave

On Tue, 13 Mar 2007 22:44:15 -0700, C J Campbell

wrote:
On 2007-03-13 17:43:50 -0700, megaMAX
said:

On Wed, 14 Mar 2007 01:18:33 +0100, Mxsmanic
wrote:

Most commercial flights are flown on autopilot for the vast majority of the
trip. Thus you would have seen autopilot corrections, not pilot corrections.

Just so you know, Msxmanic does not know any more about flight than you
do. He is not a pilot. He is just some nut who hangs out here and
pretends to know what he is talking about.

MX's knowledge is very sophomoric, and heavily stilted towards biases
introduced by inaccuracies in his simulations.

As in this case.

Minor Harmonic oscillations in flights are a natural byproduct of the
dynamic stability of modern aircraft. The Autopilot has no part in
it.

When the oscillations are on the Longitudinal axis, they are called
phugoid oscillations, I'm not sure if there is a similar term for the
roll equivolents, but it is the same deal- Essentially what is
happening is a battle between the aircraft's substantial momentum, and
the aerodynamic forces which keep it pointed into the wind... Large
out-of-trim deflections (both roll and pitch) are damped quickly, but
there is a threshold at which the amplitude of the oscillations falls
below the aerodynamics ability to produce large enough forces to damp
the behavior...

The period and amplitude of these harmonic functions are directly
related to the configuration and chord of the aerodynamic surfaces vs.
The aircraft's distribution of mass. In general, thinner aerodynamic
surfaces create stronger off-center aerodynamic forces and hence
better damping, and lighter aircraft produce weaker momentum forces
and again, fewer oscillations. Granted, 'fewer' in this case is a
matter of perception... the oscillations you were seeing were really
very minor (less than a degree), its just that the solid horizon
combined with the long arm of the wing made them more obvious than the
same fraction of a degree roll oscillation would be in a smaller
aircraft.

No MX... it has nothing to do with the autopilot...

FWIW, I remember reading somewhere that the 747 prototype actually had
a problem on its first few flights - the engineers had designed the
aerodynamic surfaces to damp the phugoid (longitudinal) harmonics
based on a theoretical perfectly rigid aircraft, however, in reality,
it turned out that the fuselage had a natural bending resonance
frequency which matched the aerodynamic harmonic frequency, and they
amplified eachother to produce an in flight longitudinal harmonic that
was actually quite substantial... the result, IIRC, was a very sick
planeload of journalists on the aircraft's first publicity flight.

For more information, read up on both Phugoid oscillations and Roll
stability via using wing dihedral.

On Mar 15, 12:14 pm, Mxsmanic wrote:
writes:
Yes, they can.

No, they cannot, except under ideal conditions, and sometimes not even then.

They do not have too. They only need to get the aircraft close enough
for wing dihedral to do the rest. Its called a dynamically stable
aircraft design, and its been a cornerstone of aviation almost since
its inception.

But what do I know, I only fly tiny planes.

My thoughts exactly.

That's funny, by your theory, stable flight was impossible until the
mid-80s...

Correction: Actually, Mxsmanic knows a great deal, _despite_ not being a
pilot.

I cannot disagree with this.

The problem is that you do not know what you do not know, and lack of
practical experience has left your knowledge with a great number of
holes that you refuse to acknowledge.

It is a typically sophomoric attitude (hence my initial impression
that you were an adolescent).

This is particularly true with respect to large aircraft, since most
of the pilots here are familiar only with the tiny aircraft they fly, whereas
he has studied both small and large aircraft.

That is a GROSS generalization.

Yes, some pilot's only care about the planes that they fly... I would
say that is actually the exception rather than the rule, however.

The rest of us have just as much a passion for aviation as yourself
AND we fly. When we're not spending our spare time in a cockpit, we
spend it learning about aircraft and aircraft systems... Aircraft
design (A particular favorite topic of mine) and other aviation
related topics... and hell, even flying sims...

More to the point: If you see an error in anything I've said, feel free to
point it out.

Your explanation of the cause of the roll oscillations was utterly
wrong, and your desire to attribute ultimate aircraft stability to
autopilot design is also largly incorrect (Except in a few isolated
(almost always military) cases of relaxed stability aircraft.

He doesn't have to pretend.

This might be a low blow but...

Isn't that the fundamental definition of Simulation?

Nor is he so insecure that he must engage in personal attacks if someone else seems to know more.

I actually agree that the personal attacks against you have grown more
disruptive than your actual sophomoric nature.

One of the aggravations I have had, however - is you do not seem to
respond to anything BUT the personal attacks - I have seen MANY
knowledgeable, polite corrections and responses to your assertions go
un-heeded while you chose only to argue with those who attacked you.
It gives the impression that you seek the negative attention over
actual helpfulness.

I still wish you'd take some time to get your information from sources
OTHER than public forums however... So many of your questions could be
answered so much easier and faster via a quick Google search.

And It would also be nice if you added an occasional "my understanding
is" disclaimer to some of your more authoritative-toned posts...

On 2007-03-14 15:59:45 -0700, Dave said:

Soooo..

How come he (MX) was able to give a rather complete and correct
answer to the poster's question?

Care to give it a try?

Dave

The fact that he is right once in awhile is no indication that he knows
what he is talking about. He is not a pilot. He is a flight-sim guy.
Even Mxs should be able to learn something. But what he says should in
no way be considered reliable.

--
Waddling Eagle
World Famous Flight Instructor

Understood, and we agree...

But he is right some of the time, along with many others here..

There are also a couple of other guys I know of who could answer
this question, probably better than anyone here....

One is a designer of autopilots, the other is an aeronautical
engineer....

.....neither is a pilot, nor has any interest in becoming one...

So, I guess many here would chastise them if they posted their
opinions here, because they are not "pilots"...

But, I guess that all works out, because Bombardier PAYS THEM BOTH
VERY WELL for their thoughts/opinions/ideas.

But, alas, like MX, they are not pilots..

D



On Thu, 15 Mar 2007 18:43:25 -0700, C J Campbell
wrote:

On 2007-03-14 15:59:45 -0700, Dave said:

Soooo..

How come he (MX) was able to give a rather complete and correct
answer to the poster's question?

Care to give it a try?

Dave

The fact that he is right once in awhile is no indication that he knows
what he is talking about. He is not a pilot. He is a flight-sim guy.
Even Mxs should be able to learn something. But what he says should in
no way be considered reliable.

EridanMan writes:

The problem is that you do not know what you do not know ...

A greater problem is that a lot of pilots here don't know, either, although
many think that they know it all once they have a license (and that,
conversely, anyone without one knows nothing). The truth is considerably less
extreme.

... and lack of
practical experience has left your knowledge with a great number of
holes that you refuse to acknowledge.

The "holes" pointed out to me consist almost exclusively of physical
sensations of flying. The mistake made by pilots here is to think that these
sensations are 99% of flying, when in fact their importance varies with the
type of flying under consideration.

This is a consequence of many pilots here being tin-can, seat-of-the-pants
pilots, with little or no experience or knowledge of other types of aircraft.
They see everything from the cockpit of a Cessna, and they think that's all
there is.

That is a GROSS generalization.

It's also a very accurate one. It's painfully obvious that many of the pilots
here are low-time, small-aircraft pilots. Everything they say reflects this
viewpoint.

Yes, some pilot's only care about the planes that they fly... I would
say that is actually the exception rather than the rule, however.

Most of them only _know_ about the plane(s) they fly. They don't know about
other planes, so they don't care about them.

They think that knowing the fine details of control pressures in a Cessna is
vitally important, but when I point out that many large aircraft don't work
this way at all, they dismiss that as unimportant. But it's not unimportant
to an Airbus pilot.

The rest of us have just as much a passion for aviation as yourself
AND we fly.

Some people have resources, and others don't.

When we're not spending our spare time in a cockpit, we
spend it learning about aircraft and aircraft systems... Aircraft
design (A particular favorite topic of mine) and other aviation
related topics... and hell, even flying sims...

Some do, some don't. Some stop half-way and then pretend about the rest.

Your explanation of the cause of the roll oscillations was utterly
wrong ...

Provide the correct explanation, then.

... and your desire to attribute ultimate aircraft stability to
autopilot design is also largly incorrect (Except in a few isolated
(almost always military) cases of relaxed stability aircraft.

See above.

This might be a low blow but...

Isn't that the fundamental definition of Simulation?

Not really. Pretending depends on imagination alone. Simulation removes part
of the need for imagination, so simulation is much less pretending than
non-simulation.

One of the aggravations I have had, however - is you do not seem to
respond to anything BUT the personal attacks ...

Many posts contain nothing else, and in fact I let most personal attacks drop,
as they are unrelated to the discussion at hand. It's hard to get people to
discuss the topic, rather than me.

This post is a case in point. You say I was wrong, but you provide no further
information and no corrections, which I find odd. You spend the rest of the
post talking about me, rather than the topic at hand.

I have seen MANY knowledgeable, polite corrections and responses to
your assertions go un-heeded while you chose only to argue with those
who attacked you.

The fact that I do not reply to a post doesn't mean that I haven't read it or
understood it. It usually just means that I have no quarrel with it and no
further questions about it.

Those who engage in personal attacks also tend to be those who give wrong
answers or incomplete answers or no answers, and so I press them for answers.
People who are aggressive in this way are often being defensive because they
know that their opinions were adopted wholesale from someone else and are
fundamentally baseless. I press them for answers in order to compel them to
look at their opinions and decide whether they are really worth clinging to
when they cannot be substantiated. I consider this a public service.

It gives the impression that you seek the negative attention over
actual helpfulness.

I'm not worried about the impression I create. I've found that people have an
enormous tendency to believe what they want to believe, and it's an exercise
in futility to try to make them think more critically. But I try to err on
the side of optimism and so I still do the above.

I still wish you'd take some time to get your information from sources
OTHER than public forums however ...

Most of my information comes from other sources, since it is hard to find
people here who actually know what they are talking about. USENET is just one
of many sources.

So many of your questions could be
answered so much easier and faster via a quick Google search.

I do Google searches regularly, although I don't have as much faith in them as
you might.

And It would also be nice if you added an occasional "my understanding
is" disclaimer to some of your more authoritative-toned posts...

Why? To spare the overinflated egos of a minority? Why would I say something
that is _not_ my understanding? How could anything I say (or anything anyone
else says) be anything _other_ than an understanding?

--
Transpose mxsmanic and gmail to reach me by e-mail.

EridanMan writes:

They do not have too. They only need to get the aircraft close enough
for wing dihedral to do the rest. Its called a dynamically stable
aircraft design, and its been a cornerstone of aviation almost since
its inception.

Until Airbus came along.

--
Transpose mxsmanic and gmail to reach me by e-mail.

EridanMan writes:

Minor Harmonic oscillations in flights are a natural byproduct of the
dynamic stability of modern aircraft. The Autopilot has no part in
it.

Do these oscillations cause control surfaces to move by themselves? Are they
asymmetrical?

When the oscillations are on the Longitudinal axis, they are called
phugoid oscillations, I'm not sure if there is a similar term for the
roll equivolents ...

Dutch roll and spiral come to mind, although they are not limited exclusively
to the roll axis.

No MX... it has nothing to do with the autopilot...

If the control surfaces are moving, either the pilot or the autopilot is
acting upon them. If the corrections are asymmetrical, this would tend to
exclude the hypothesis of harmonic oscillations. Also, roll harmonics often
extend over periods of minutes in large aircraft and would not be obvious just
by watching the wing outside the window.

--
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