LY777
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747 Upper Deck:is This True?

Wed Sep 20, 2006 5:38 pm

A friend of mine who travels a lot on 744s on the upper deck(biz class) told me that on the upper deck of 747s, we don't feel any vibration, the turbulences are far less important than on the lower deck.
Is this true?
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kiwiandrew

RE: 747 Upper Deck:is This True?

Wed Sep 20, 2006 5:44 pm

the upper deck has always seemed noisier to me than the lower deck because of the way the air flows around the fuselage - but that is only my subjective opinion - I have only done 3 or 4 trips upstairs and 3 or 4 downstairs so I guess I don't have as much experience as your friend to base my opinion on
 
HUYguy
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RE: 747 Upper Deck:is This True?

Wed Sep 20, 2006 5:48 pm

Surely it would be the same on both decks beings as the whole plane shakes in turbulence?
 
zvezda
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RE: 747 Upper Deck:is This True?

Wed Sep 20, 2006 5:53 pm

There is less turbulence forward than aft, so there would be less at the average point on the upper deck than the average point on the lower deck. The nose on the lower deck would have the least turbulence which is one of the reasons why most airlines locate their F cabins there.
 
deaphen
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RE: 747 Upper Deck:is This True?

Wed Sep 20, 2006 6:11 pm

Quoting Zvezda (Reply 3):
There is less turbulence forward than aft, so there would be less at the average point on the upper deck than the average point on the lower deck. The nose on the lower deck would have the least turbulence which is one of the reasons why most airlines locate their F cabins there

correct me if i am wrong but i thought the least turbulence is in the centre of the place.. because the plane will be most turbulent at the front and the back. That was the conclusion i got once wheni asked this same question.

regards
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andz
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RE: 747 Upper Deck:is This True?

Wed Sep 20, 2006 6:20 pm

The upper deck is the place to be on a 747, in my experience it is quieter, it certainly rattles less than the main deck cabin and in SAA's case has better legroom too (Y class).
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trekster
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RE: 747 Upper Deck:is This True?

Wed Sep 20, 2006 6:21 pm

Upper deck still gets turbulance. I had to grab hold of a glass of wine flying LHR-YYZ when we hit some rough stuff.

Back of the plane indeed is the shaky part. SFO-LHR I was RIGHT at the back and my knees were moving while seated it was that bumpy. I was so tired i did not care and was asleep for 3 hours till the crew woke me
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Gr8Circle
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RE: 747 Upper Deck:is This True?

Wed Sep 20, 2006 9:26 pm

I've travelled on the upper deck of 742's, 743's and 744's.....did not really feel it is any better than the main deck in terms of turbulence or vibrations....

What I don't like about the UD is the slant in the windows and the gap between the seat and the window.....on the other hand, due to the position, the wing does not significantly block your view..... smile 
 
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EK413
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RE: 747 Upper Deck:is This True?

Wed Sep 20, 2006 10:59 pm

In my opinion which comes with experience from alot of trips.....I believe you experience less and probably NO turbulence in the centre of the aircraft as opposed to the aft of the aircraft....

EK413
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Tod
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RE: 747 Upper Deck:is This True?

Wed Sep 20, 2006 11:04 pm

Quoting LY777 (Thread starter):
on the upper deck of 747s, we don't feel any vibration,

I haven't noticed the difference.

Quoting Gr8Circle (Reply 7):
What I don't like about the UD is the slant in the windows and the gap between the seat and the window

I like the gap and the sidewall stow box to put my stuff in. When trapped in a window seat long haul it is nice not to need to get into the overhead bin during the flight.

Quoting Andz (Reply 5):
it certainly rattles less than the main deck cabin

That can be caused by the age and manufacturer of the interior components too.

Tod
 
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hotelbravo
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RE: 747 Upper Deck:is This True?

Wed Sep 20, 2006 11:18 pm

Quoting Zvezda (Reply 3):

It is actually not as simple as "quiet in front and noisy in the back". The 747 is known to have a particularly noisy flight deck due to the airflow around the cockpit. So it doesn't surprise me that the top passenger cabin is said to be noisier than the main deck.
 
sevenforeseven
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RE: 747 Upper Deck:is This True?

Wed Sep 20, 2006 11:52 pm

Aircraft are always more "turbulent" at the rear 3/4 section. This is due to the fact that an aircraft fusealage actually flexes. B757 and A340-600 are very prone to this phenomina. It is known as fish tailing effect.
As for upper deck, well it probably feels less turbulant here because of its forward position.
 
tonyban
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RE: 747 Upper Deck:is This True?

Wed Sep 20, 2006 11:58 pm

I have only flown once in the upper deck. A Virgin Atlantic flight from SFO to LHR. Still felt plenty of turbulance but what stood out more was the sheer wind noise up there. The 'hump' definatelt causes the air flow to generate a lot of noise. Very noisy indeed.
 
FlyBoy84
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 12:23 am

Overall the 747 is a very stable plane anyway, to me. I've flown on one and there was some turbulence during the flight. But I can imagine that a 737 would have had more  bouncy  to the ounce that that 747!
 
aviateur
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 2:03 am

It doesn't make a whole lot of difference, but the smoothest place to sit is that portion of the cabin closest to the plane's centers of lift and gravity. Basically, that means the middle.

With many aircraft, the tail section is further from CL and CG than the nose -- with the yaw damper correcting for displacement and knocking the tail back and forth. This means the very front tends to be smoother than the very back. Thus it's possible you'll find a slightly nicer ride on the 747's upper deck than in row 63.

Noise is another matter. The upper deck does tend to be loud due to its thin diameter combined with airflow over and around its surface.

I wrote an article about this, which Airliners will not allow me to link to, but trust me...

PS

[Edited 2006-09-20 19:11:29]
Patrick Smith is an airline pilot, air travel columnist and author
 
aviateur
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 2:05 am

Accidental double post... sorry.

[Edited 2006-09-20 19:07:18]
Patrick Smith is an airline pilot, air travel columnist and author
 
SkyvanMan
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 2:11 am

I don't remember the specifics about whether I felt turbulence or not but I vividly remember flying upper deck on UA from LAX to SYD and it was awesome. I loved the small cabin and it felt really more personalized and special, especially when we were on the gorund or I looked and could see parts of the plane below me.
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roseflyer
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 2:36 am

Quoting Zvezda (Reply 3):
The nose on the lower deck would have the least turbulence which is one of the reasons why most airlines locate their F cabins there.

From an engineering stand point I can't think of a single reason why the center of gravity of the plane shouldn't be the part that experiences the least turbulence. I won't go technical, since I can't say I fully understand turbulence's effect. Honestly I kind of doubt anyone ever had gone in to the research that would be required to make such a calculation. The reason is that when you get something complicated like an airplane, you go so far beyond the models and fundamental equations that are central to the understanding of mechanical systems. Everything turns theoretical. There is no equation or way to exactly model the airflow around a wing or an airframe. Everything is based on empircal evidence and is just a guess. You can't even exactly model airflow around a tennis ball. Doesn't that make you feel good about the engineering that goes in to designing something like the 747?

With that said, the center of gravity should experience the least turbulence. The reason is that there is little damping in the fuselage since it is close to being modeled as a rigid structure (the wing is definitely the opposite, which is why you will see it move and for lack of a better term, flap). Since the fuselage is a rigid structure, the axis of rotation for turbulence when it is rotational and not translational should be around that point. Therefore rotational turbulence such as any turbulence through one of the three axes will go through that point and it will not move. You only have translational turbulence left which will be felt equally throught the plane. There are four ways to feel motion. Rotate up and down (pitch). Rotate left and right (yaw). Rotate axially (roll). Translate in any direction. So with this explanation, the upper deck should feel more turbulence than say the business class cabin on the lower deck or front part of economy.

With regards to noise, the nose of the 747 is the quietest place on an airplane in flight at cruising speed due to reduced wind noise and low engine noise. The wind noise is due to airflow along the nose being different since from what I have heard, it is more laminar or at least in a transition phase from laminar to turbulent flow at the nose since the airstream has not fully developed in to being turbulent as the nose slices through the air and is not a constant diameter. It may be laminar instead of being turbulent as it is along the side of the plane, and thus will make less noise since the air in contact with the fuselage is moving at a comparatively lower speed than it is along the concentric lenght that is experiencing turbulent airflow at a full 400+mph. I can explain further if people want, but I'm not completely certain about that. However, I do know that the 747 is a bit louder since it uses a louder environmental control system, so you hear a lot of air blowing around inside the cabin when compared to an A330 or A340. This has little to do with A versus B, but rather the separate contractors that designed the systems. Airbus and Boeing don't design the cabin pressurization system, but they do decide the specifications for it.
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MCOflyer
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 2:48 am

Quoting Sevenforeseven (Reply 11):
B757 and A340-600 are very prone to this phenomina.

That is defintely true. Its worse for the 753.

MCOflyer
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klkla
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 2:52 am

It's amazing how so many people can have a different experience from the same thing.

I have flown United 744s many times in business and first and I definitely prefer the upper deck. IMO it's much quieter (can't say whether there is more or less turbulence, though). First class in 744 is very noisy for some reason, much more so than any other aircraft I have flown.
 
spacecadet
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 3:10 am

Quoting RoseFlyer (Reply 17):
From an engineering stand point I can't think of a single reason why the center of gravity of the plane shouldn't be the part that experiences the least turbulence.

There is more than one kind of turbulence, and several other phenomena that feel like turbulence but aren't. These factors and others make the rear of any plane bumpier than anywhere else.

Quoting RoseFlyer (Reply 17):
With that said, the center of gravity should experience the least turbulence. The reason is that there is little damping in the fuselage since it is close to being modeled as a rigid structure (the wing is definitely the opposite, which is why you will see it move and for lack of a better term, flap).

Airplane fuselages are hardly rigid structures! They are in fact designed to flex/expand/contract in a number of different ways. Otherwise, modern flight would not even be possible - to operate at temperatures from 120F to -60F, speeds through turbulent air at 320 knots, and altitudes from below sea level to 47,000 feet, a fuselage *must* flex.

That's ignoring the fact that the "center of gravity" in any airliner is almost always towards the back of the plane and is rarely the center of the wing (that's what stabilizers and trim settings are for). So even if you meant what you actually said there, you'd be agreeing with me. But I know you're not saying what you mean up there.

The 747 in particular is known for having a pretty aggressive yaw damper system that actually made passengers in the rear of the plane sick on some of its early flights. (It was calmed down a bit over the years, but is still more aggressive than on other airliners.) The movement from the yaw dampers is, well, damped by the time it reaches the front of the plane - the nose still moves opposite to the tail, but not nearly as abruptly as the tail.

There are obvious control and aerodynamic surfaces at the rear of the plane that do not exist at the front. An eddie that passes over one of the stabilizers will have a direct effect on the rear of the plane. That effect will also be damped before it reaches the nose. Depending on the type of wind gust, it might not be felt at all in the front of the plane (a gust that hits the tail directly, for example, would not rotate the plane on its "gravitational" axis - it would rotate it around its nose).

There is of course vibration caused by engine exhaust also, which create eddies near the fuselage behind them. This is the worst on takeoff and landing, but in my experience can be felt pretty much all the time throughout the flight. The noise of the engines also creates vibration through the floor, which is not experienced as "turbulence" but does make the rear of the plane less comfortable and serene than the front.

Taken all together, yeah, the front of a 747 is a lot smoother than the rear. I can't really speak to the upper deck as I've never ridden up there, but I would think it would be just as smooth, though possibly noisier due to wind noise from above (which is not present on the lower deck).
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Newark777
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 3:14 am

Quoting Sevenforeseven (Reply 11):
Aircraft are always more "turbulent" at the rear 3/4 section. This is due to the fact that an aircraft fusealage actually flexes. B757 and A340-600 are very prone to this phenomina. It is known as fish tailing effect.

I sat in the back of a CO 753 through some (relatively) heavy turbulence, and you can almost see the fuselage flexing and torquing. Pretty neat.

Harry
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Vir744
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 3:58 am

Quoting Spacecadet (Reply 20):
That's ignoring the fact that the "center of gravity" in any airliner is almost always towards the back of the plane and is rarely the center of the wing (that's what stabilizers and trim settings are for). So even if you meant what you actually said there, you'd be agreeing with me. But I know you're not saying what you mean up there.

The centre of gravity is always within the wings Mean Aerodynamic Chord (MAC = average chord line over the span of the wing) and the C of G moves during flight, primarily as fuel is burned. The stab trim settings are required due to the difference between the centre of pressure and the C of G. As the weight of the aircraft acts through the C of G and the lift acts through the C of P a lever arm is formed causing the aircraft to have a pitch up or pitch down tendency. This is overcome by the stabiliser trim and where installed fuel transfer trimming.

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roseflyer
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 4:55 am

Quoting Spacecadet (Reply 20):
That's ignoring the fact that the "center of gravity" in any airliner is almost always towards the back of the plane and is rarely the center of the wing (that's what stabilizers and trim settings are for). So even if you meant what you actually said there, you'd be agreeing with me. But I know you're not saying what you mean up there.

From what I know (and I've never taken any advanced aerodynamics classes that related to airplane design, so my knowledge is limited to general fluid dynamics) the horizontal stabalizor does not produce lift for the purpose of supporting the weight of the airplane. It is used for control only. Therefore the center of gravity will be over the wing. I know for sure that it is on every jet that I have ever heard of.

What I said I guess doesn't make sense since I just assumed that the effect of damping would be less than that of the central axis of the plane. I'm still not conviced that it isn't. If the tail moves one way, I would assume that the nose to some degree would move the other way based on the center of gravity if the force causes the plane to rotate. An airplane is far more complicated than something that I've studied, but if you push one end of a beam at an end, it rotates about its central axis. I think the nose would move. But yes more forces would be generated around the vertical and horizontal stabalizors. Damping I know will have an effect, but the sheer mass of the system would also cause there to be the least motion at the center of gravity. All the parts of the airplane damp forces out before they get to the CG. So it would have to be a significant difference in forces at the front and back to make up for this effect. I can't say how much for sure since I decided not to study virbration systems and thinking about those higher order differential equations is something that I'd prefer not to do.

Quoting Spacecadet (Reply 20):
The 747 in particular is known for having a pretty aggressive yaw damper system that actually made passengers in the rear of the plane sick on some of its early flights.

Wow I did not know that. I've never worked on anything structural for airplanes. I work on aviation power systems, so something like damping by the fuselage is out of my area of knowledge other than what I have learned in college.

Quoting Spacecadet (Reply 20):
Airplane fuselages are hardly rigid structures! They are in fact designed to flex/expand/contract in a number of different ways. Otherwise, modern flight would not even be possible - to operate at temperatures from 120F to -60F, speeds through turbulent air at 320 knots, and altitudes from below sea level to 47,000 feet, a fuselage *must* flex.

I know a plane has to flex, but there is a difference between flexing and damping. The stress caused by temperature and pressure differences does cause strain, but that strain isn't the same that will damp a force caused by turbulence. Axial strain wouldn't have much if any effect on what happens to a plane as it undergoes turbulence. Also since a plane is essentially a tube, the axial forces, which cause the greatest stress on the airplane are where the aluminum is strongest. The longitudinal loads that would make a difference in the effect of turbulence are significantly less. Where is the line between damping effects of the fuselage and transmitting the forces? The wing for sure is far less rigid than a fuselage, but naturally a tube is going to be far more rigid than something like a wing, which has a load supporting structure that is made of long beams.

Quoting Spacecadet (Reply 20):
(a gust that hits the tail directly, for example, would not rotate the plane on its "gravitational" axis - it would rotate it around its nose).

No it will not. If the gust just hits the tail perpindicularly, then it will absolutely rotate about its center of gravity. However it isn't that simple. This goes back to this being an insanely difficult thing to model, but a gust is likely to hit the entire plane, but effect localized parts such as the tail more. The whole plane may move laterally, but also will rotate about its center of gravity. It can rotate in all three dimensions. Basic dynamics has proved that systems always rotate about their center of mass. Unless you anchor the nose to a fixed point, or add additional forces, there is no possible way that a plane would rotate about its nose as a whole. The plane may roll along its line of center of gravity which passes throught he nose and fuselage to the tail, but it will also rotate about the vertical axis too if there is a force on the tail and yaw left or right. To simplify, if you push the tail of a plane, it will move in three ways, and only one way is a rotation about the nose. The other way is a lateral motion and finally it will yaw. Only one point will not move based on that force, and that point may or may not even be on the plane, but the center of gravity will only be affected by one of the three motions whereas the nose will be affected by two.
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ikramerica
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 6:14 am

Quoting SkyvanMan (Reply 16):
I loved the small cabin and it felt really more personalized and special, especially when we were on the gorund or I looked and could see parts of the plane below me.

I always love how people say the "small cabin" of the upper deck is great, yet so many say that they wouldn't want to be 'cramped' into a 757 on a long haul flight, even in J or F. Not saying you say this, just an observation.
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zvezda
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 6:17 am

Quoting RoseFlyer (Reply 17):

From an engineering stand point I can't think of a single reason why the center of gravity of the plane shouldn't be the part that experiences the least turbulence. I won't go technical, since I can't say I fully understand turbulence's effect. Honestly I kind of doubt anyone ever had gone in to the research that would be required to make such a calculation. The reason is that when you get something complicated like an airplane, you go so far beyond the models and fundamental equations that are central to the understanding of mechanical systems.

I had once assumed the same thing. However, a couple of professionals have explained it to me and I more or less grasped a semblence of understanding. I think SpaceCadet gets it or at least some of it. I've been told about another factor, but I won't try to repeat it. I'm sure there are people here who understand it better than I do.

As for it being theoretical, Airbus and Boeing have both fitted accelerometers throughout testbed aircraft and found that turbulence is most severe at the tail and least severe at the nose.
 
Lemurs
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 6:40 am

Quoting Ikramerica (Reply 24):
I always love how people say the "small cabin" of the upper deck is great, yet so many say that they wouldn't want to be 'cramped' into a 757 on a long haul flight, even in J or F. Not saying you say this, just an observation.

Thanks for saying what I was thinking but didn't feel like typing.  rotfl 

I sometimes think that the loudest narrowbody complainers would be perfectly happy if you sold them a coffin with nice satin sheets and told them that it was more "Exclusive" than the rest of the cabin. Load them individually so that they can't see everyone has the same thing as them, and viola...you have satisfied self-important people who don't know they're not actually special. I think you can make a business plan for this.  laughing 
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lehpron
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 10:16 am

Quoting Zvezda (Reply 3):
The nose on the lower deck would have the least turbulence which is one of the reasons why most airlines locate their F cabins there

No, first class is there because it is most forward convinience for those passengers, like any F class seatmaps. Besides, the moment arm of being far from the center of rotation wouldn't be any different than if you were in the aft most economy seat. Likewise, sit above the centerline is still a distance from the center, in two dimensions.

Quoting Aviateur (Reply 14):
but the smoothest place to sit is that portion of the cabin closest to the plane's centers of lift and gravity.

Center of rotation is a bit more correct, not always the middle, per design.
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satx
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 11:33 am

I'm no expert on aerodynamics, but I have flown both decks of a 747 before. My personal opinion is that the upper deck is generally quieter than most of the main deck and that it has less turbulence than the rear portion of the main deck. I also consider the 744 to be significantly quieter than the 777, at least in Y.
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comorin
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 12:00 pm

I've found that the upper deck is quieter and much less bumpy than other parts.

One observation for all you finite element types is that a bump felt as a sharp displacement in midsection becomes less sharp but has greater displacement towards the rear. I think this makes sense if you simplified the aircraft as a oscillated cantilever damped by the stabilizer at the rear end.
 
Vimanav
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 1:45 pm

Quoting Sevenforeseven (Reply 11):
This is due to the fact that an aircraft fusealage actually flexes. B757 and A340-600 are very prone to this phenomina

you can add the DC8-61/63/71/73 to that list

rgds//Vimanav
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speedracer1407
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 3:37 pm

Quoting Spacecadet (Reply 20):
That's ignoring the fact that the "center of gravity" in any airliner is almost always towards the back of the plane and is rarely the center of the wing (that's what stabilizers and trim settings are for). So even if you meant what you actually said there, you'd be agreeing with me. But I know you're not saying what you mean up there.

I'm not sure what you mean by "towards the back of the plane," but the center of gravity, in any commercial airliner, is forward of the center of lift. Thus, the horizontal stabilizer produces a relatively mild negative lift in level flight.
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Luxair
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 5:49 pm

I traveled many times on the upper Deck and can only confirm & agree with ur friends statement that there are less would even dare to say much less vibrations originating from turbulences up there! Dont know why but probably has to do with aerodinamical issues. Regarding the noise I would say but that's my personel oppinion that the noise is also less at least less than the people sitting lower floor behind the wings thus behind the engines! Was sitting once in the nose and it was relatively quiet there!
 
keysman73
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 5:57 pm

Just back from flying Lufthansa upper deck and I have to say that I thought the "wind noise" was much louder than down stairs.
It still seemed to be affected by turbulence in the same way as the rest of the aircraft - there were the same periods of choppy flight along with smooth flight.
Can't really say it was significantly different....

But some noise-cancelling headphones and the extra legroom of First more than makes up for it...  Smile

Have to agree with one of the previous contributors, though, about the angle of the windows - this was noticeably different.

Cheers.

Alan.
 
roseflyer
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RE: 747 Upper Deck:is This True?

Thu Sep 21, 2006 9:51 pm

Quoting Keysman73 (Reply 33):
Just back from flying Lufthansa upper deck and I have to say that I thought the "wind noise" was much louder than down stairs.

Out of curiousity, where downstairs are you comparing it to. I've flown on the upper deck many times and do notice a significant increase in wind noise when compared to the nose section. I haven't flown in the back of a 747 since I was a child, so I really can't comment on the noise back there.

As far as turbulence, it would be interesting to see data on this subject.
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keysman73
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RE: 747 Upper Deck:is This True?

Fri Sep 22, 2006 12:52 am

Well I flew out to Hong Kong with Thai in normal economy before coming back with LH.
I was in row 52 going out, so probably two-thirds of the way back and I remember it being very quiet in terms of wind noise. Also, very little turbulence, but I reckon that this is very flight-specific and surely must change dependent on the weather.

I suppose it's all relative anyway as if you are experiencing turbulence in one area of the plane, there's not really any way to experience it in another area at the same time - and therefore no way of comparing it. It could be exactly the same.

Interesting topic though....more data would be revealing...

Cheers.

Alan.
 
roseflyer
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Joined: Fri Feb 13, 2004 9:34 am

RE: 747 Upper Deck:is This True?

Fri Sep 22, 2006 2:12 am

Quoting Keysman73 (Reply 35):
I suppose it's all relative anyway as if you are experiencing turbulence in one area of the plane, there's not really any way to experience it in another area at the same time - and therefore no way of comparing it. It could be exactly the same.

Well someone talked about accelerometers measuring the different effects, and that could measure it in different parts of the plane. Overall though, turbulence is really more specific to the specific flight and specific day's weather conditions than where you are sitting in the plane. You might feel more vibration in certain spots, but on a rough transpacific crossing, it doesn't matter where you sit, it will still be rough. No where can be smooth. The upper deck is nice since it gives the narrowbody feeling on a widebody if you like that feel. I prefer it that way personally since it cuts down on noise since there are fewer people, but my favourite spot on the 747 is still the nose because once the gear comes up, it is silent.
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pygmalion
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Joined: Thu Jun 29, 2006 12:47 am

RE: 747 Upper Deck:is This True?

Fri Sep 22, 2006 2:47 am

The CG of any commercial jet is always forward of the center of lift for stability reasons. It is a certification criteria. The center of lift is for practical purposes at 25% of the mean aerodynamic chord. On a swept wing airliner (all of them basically) this would be about a third of the way back from the front of the wing at the wing root along the body. The CG is a few feet farther forward. You can guesstimate it from the outside as it is always forward of the main gear so the airpane wont fall on its tail while parked. The cg is forward of the lift center so that the nose will fall on its own during a stall. In aero terms, positive stability. If the cg was aft of the wing, when the aircraft stalled and the tail airflow was disrupted by the wing in front of it, the aircraft would flip over on to its back. Bad result. Makes for a long stall recovery.

Because the aircraft flexes about the cg... and the controlling surfaces for the most part are behind that location, the least excursion or movement is in the front and the front tends to move less and is there is a smoother ride in the front. In the same way that if you struck an arrow in flight, most of the movement would be behind the cg as the restoring aero forces push the center of lift back in line from behind and the front less so. Another point to consider is that when looking at aircraft as it moves side to side, the center of "lift" or airpressure is even father aft as the tail is much larger in a side view than anything else forward of it. This longer lever arm means that the side to side motion is much more apparent in the aft cabin than the front.

All of this ignores wind noise which is much more a factor of disturbances in the flow field than distance front to back. It is true though that as the airflow trips to turbulent as you go aft, the boundary layer grows and moces the noise farther away from the skin. If it wasnt for the engines the aft part of the airplane would be quieter.

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