Problems in a commercial flight

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.

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?

--
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

**THE-RFI-EMI-GUY** writes:

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?

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. 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.

There is jet fuel burning inside a running jet engine all the time, so a
visible flame isn't necessarily a cause for panic or concern.

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

On Mar 15, 11:59 am, 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?

More than possible that the poster had a middle ear infection.
Not having instruments and the training to use them while back among
the self loading cargo how could any-one tell what the aircraft was
doing?

george writes:

More than possible that the poster had a middle ear infection.

I don't see the connection between a middle-ear infection and what he saw or
believed.

Not having instruments and the training to use them while back among
the self loading cargo how could any-one tell what the aircraft was
doing?

One can estimate visually, but with limited visibility this is difficult.
Even pilots cannot depend on visual cues alone, which is why they have
instruments.

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

Even pilots cannot depend on visual cues alone, which is why they have
instruments.


Yes, they can.
But what do I know, I only fly tiny planes.

-Kees

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.

Mxsmanic wrote in
:

george writes:

More than possible that the poster had a middle ear infection.

I don't see the connection between a middle-ear infection and what he
saw or believed.


of course you don't, but it's the first thing I thought of..

wonder why?


bertie

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.

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.

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