JAAlbert
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Why Are The 380 Cabin Walls So Thick?

Fri Oct 11, 2013 7:19 pm

In looking at cabin photos of the 380, it appears that the side walls are extremely thick. What is the reason for that? Is it additional insulation or additional support?
 
trent900
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RE: Why Are The 380 Cabin Walls So Thick?

Fri Oct 11, 2013 8:26 pm

If you take a look at the following photo it should answer you question -

http://www.airliners.net/photo/2328466/L/

The A380 frames are fairly deep to support, I assume, the large oval cross section. Add insulation onto that and you probably get a good 8 inches  

D.
 
Max Q
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RE: Why Are The 380 Cabin Walls So Thick?

Sat Oct 12, 2013 4:58 am

Doesn't look all that thick, a lot of what you are seeing is insulation.
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sccutler
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RE: Why Are The 380 Cabin Walls So Thick?

Sat Oct 12, 2013 5:02 am

To accommodate the spliced wires?

I kid!
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Buyantukhaa
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RE: Why Are The 380 Cabin Walls So Thick?

Mon Oct 14, 2013 9:03 am

I also noticed that when looking out of the window it is almost like a tunnel, quite unlike any other aircraft I've flown on.
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JAAlbert
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RE: Why Are The 380 Cabin Walls So Thick?

Mon Oct 14, 2013 10:30 pm

Quoting BuyantUkhaa (Reply 4):
I also noticed that when looking out of the window it is almost like a tunnel, quite unlike any other aircraft I've flown on.

Yes, this is exactly what I was referring to. Trent1's response above, I think supplies the answer - the sidewall frame is pretty thick.
 
kenanc
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RE: Why Are The 380 Cabin Walls So Thick?

Sun Nov 03, 2013 8:10 pm

Wish they could use all that extra space to make the seats wider... lol.
 
prebennorholm
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RE: Why Are The 380 Cabin Walls So Thick?

Mon Nov 04, 2013 12:33 am

I haven't flown on an A380, but it has been said by others that the cabin is pretty quiet, almost as quiet as the front rows of an MD-90. Likely Airbus put good sound isolation up high on the priority list. It doesn't go together with thin walls.
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Starlionblue
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RE: Why Are The 380 Cabin Walls So Thick?

Mon Nov 04, 2013 1:36 am

Quoting prebennorholm (Reply 7):
I haven't flown on an A380, but it has been said by others that the cabin is pretty quiet, almost as quiet as the front rows of an MD-90. Likely Airbus put good sound isolation up high on the priority list. It doesn't go together with thin walls.

I would agree that it is about as quiet as the front of an MD-90. Apart from the insulation, those engines are pretty darned quiet.
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bikerthai
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RE: Why Are The 380 Cabin Walls So Thick?

Mon Nov 04, 2013 10:52 pm

There's a couple of engineering reason why the A380 frames are so deep (I am assuming that the frame spacing is the same as other models):

1) The larger diameter reduces the beneficial effect of hoop tension.

2) I heard that the A380 is design to fly at 6000 ft altitude cabin pressure. This increasing the strength requirement for the frame.

bt
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HAWK21M
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RE: Why Are The 380 Cabin Walls So Thick?

Thu Nov 14, 2013 3:33 pm

It does not look more thicker than other types in the pic.....why do you say so?.
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DUSint
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RE: Why Are The 380 Cabin Walls So Thick?

Thu Nov 14, 2013 5:48 pm

Quoting HAWK21M (Reply 10):
It does not look more thicker than other types in the pic.....why do you say so?.

Yes, I wondered about that, when reading the thread the first time some weeks ago.

OTOH, it gets more interesting when looking at the completed plane with insulation etc.
Here you can see it fairly good - they are massive:
http://www.airliners.net/photo/Malay...d=bd87f1a43de0e517e0591fc9b019659f
 
WingedMigrator
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RE: Why Are The 380 Cabin Walls So Thick?

Fri Nov 15, 2013 12:34 am

I'm not sure why this is such a mystery. The lower deck walls need to carry the weight of the upper deck and all cabin luggage bins, which is far heavier than the load of a conventional single-deck crown structure.

The aircraft is certified for up to 315 passengers upstairs, so you've got:
315 people x 70 kg = 22 tons of people
315 seats x 15 kg = 5 tons of seats
853 hand luggage x 8 kg = 7 tons of hand luggage
deck floor, fittings and other furnishings ... let's say 5 tons

That's roughly 40 metric tons (about like a large loaded semi-trailer truck) supported by the side walls through all the different loading cases that go up to multiple G's. It's really no wonder the side walls need to be so beefy.
 
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CALTECH
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RE: Why Are The 380 Cabin Walls So Thick?

Sun Nov 17, 2013 10:21 pm

May not be beefy enough.

http://www.aviationweek.com/Article....l/avd_11_05_2013_p03-01-633564.xml

"EASA Mandates A380 Fuselage Check For Fatigue Cracking
November 05, 2013"

That big a airframe, bound to be some unexpected cracks that will show.
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zeke
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RE: Why Are The 380 Cabin Walls So Thick?

Mon Nov 18, 2013 6:10 am

Quoting CALTECH (Reply 13):

The AD refers to one fitting on one frame found during fatigue testing.
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CALTECH
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RE: Why Are The 380 Cabin Walls So Thick?

Thu Nov 21, 2013 12:58 am

Quoting zeke (Reply 14):
The AD refers to one fitting on one frame found during fatigue testing.

The Airbus documents refer to the fittings on both the LH and RH sides of frame 56. And rather than just poo pooing the AD, maybe it would be best to read Airbus's own words about this AD.

http://ad.easa.europa.eu/ad/2013-0266

"During full scale fatigue testing of the A380 aeroplane, cracks were detected on
a cruciform fitting at frame (FR) 56. The results of the subsequent investigations
determined that the subject cracks were fatigue related and initiated by high
local stress.

This condition, if not detected and corrected, could reduce the structural
integrity of the wing.


To address this potential unsafe condition, Airbus issued Service Bulletin (SB)"

I like how Airbus says if the crack depth is more than 5mm, that Airbus should be contacted.
Think it is more significant than "one fitting on one frame."
Fatigue cracks that impair the structural integrity of a wing are not good.
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bikerthai
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RE: Why Are The 380 Cabin Walls So Thick?

Thu Nov 21, 2013 4:13 am

What is this Cruciform fitting? I am not familiar with this term on the Airbus.

bt
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Max Q
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RE: Why Are The 380 Cabin Walls So Thick?

Thu Nov 21, 2013 6:53 am

What are you really asking ?


While the 'cabin walls' may appear to be quite thick a large part of that is the interior cabin structure which I doubt is load supporting, the fuselage skin obviously does support loads and is nowhere near as thick.
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zeke
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RE: Why Are The 380 Cabin Walls So Thick?

Thu Nov 21, 2013 8:43 am

Quoting CALTECH (Reply 15):
maybe it would be best to read Airbus's own words about this AD

Do you think I just guessed it was one fitting on one frame found during fatigue testing as I said above, or do you think I might have actually have read it ???
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bikerthai
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RE: Why Are The 380 Cabin Walls So Thick?

Thu Nov 21, 2013 3:33 pm

Quoting Max Q (Reply 17):
While the 'cabin walls' may appear to be quite thick a large part of that is the interior cabin structure which I doubt is load supporting,

From a fuselage interiors stand point, the thickness of the wall is really caused by the stack-up of the stringers and frames. Most of the insulation is placed in-between- the frames and is usually not as thick as the frames deep.

So as you look along the wall, the "high spot" would be were the frames are. The thickness of the sidewall and the insulation in that location is not very much (less an inch?) versus the depth of the frames (4-6 inches or higher). The low spot are where the sidewall are sculptured toward the skin where you only have the thickness of the stringers and the insulation. Stringers are about 2" (or taller for larger aircraft) and insulation could be anywhere between 2 to 4 " (I would guess). These are all estimate numbers from memory. Not sure how accurate it is anymore.

bt
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WingedMigrator
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RE: Why Are The 380 Cabin Walls So Thick?

Fri Nov 22, 2013 1:46 am

Quoting bikerthai (Reply 16):
What is this Cruciform fitting? I am not familiar with this term on the Airbus.

It is a cross-shaped fitting that joins a center wing box stringer, a fuselage frame, and an outer wing box stringer. There is a nice diagram of something similar in this article. It is located in an area rather famously known as the "wing-body join," the point of convergence for a lot of stresses that have caused trouble in numerous airplane designs.
 
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CALTECH
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RE: Why Are The 380 Cabin Walls So Thick?

Fri Nov 22, 2013 2:32 pm

Quoting zeke (Reply 18):
Do you think I just guessed it was one fitting on one frame found during fatigue testing as I said above, or do you think I might have actually have read it ???

Why was it left out that it could affect the structural integrity of the wing ? Skipped over that part it seems. Funny that.
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DUSint
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RE: Why Are The 380 Cabin Walls So Thick?

Fri Nov 22, 2013 3:23 pm

Quoting bikerthai (Reply 19):
From a fuselage interiors stand point, the thickness of the wall is really caused by the stack-up of the stringers and frames. Most of the insulation is placed in-between- the frames and is usually not as thick as the frames deep.

Thank you for that. Makes perfectly sense when having a detailed look at the photo in the opening post and the temporary protections of the stringers.

Quoting CALTECH (Reply 21):
Why was it left out that it could affect the structural integrity of the wing ? Skipped over that part it seems. Funny that.

But you left it out in your original post of the AD yourself...?? That makes it even more funny...
 
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CALTECH
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RE: Why Are The 380 Cabin Walls So Thick?

Fri Nov 22, 2013 4:20 pm

Quoting DUSint (Reply 22):
But you left it out in your original post of the AD yourself...?? That makes it even more funny...

Sorry, actually original post was about a article about the problem, nothing about the AD. Post about the AD included it. Funny how the Airbus fanboys come out and make false and wild assumptions. That is the funniest.
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bikerthai
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RE: Why Are The 380 Cabin Walls So Thick?

Fri Nov 22, 2013 7:09 pm

Quoting WingedMigrator (Reply 20):
It is located in an area rather famously known as the "wing-body join," the point of convergence for a lot of stresses that have caused trouble in numerous airplane designs.

So this fitting is very critical indeed right? A crack here would be significant even if it's only one or two fittings per aircraft.

Replacing/repair the fitting may not easy either right. Although it may be easier than the 787 wing root fix.

bt
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CALTECH
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RE: Why Are The 380 Cabin Walls So Thick?

Sat Nov 23, 2013 2:43 pm

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WingedMigrator
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RE: Why Are The 380 Cabin Walls So Thick?

Sun Nov 24, 2013 5:53 am

So frame 56 is at the rear wing spar.
 
StTim
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RE: Why Are The 380 Cabin Walls So Thick?

Sun Nov 24, 2013 11:53 am

All aircraft are subject to Airworthiness Directives. For instance a quick scan finds Docket No. FAA-2013-0625; Directorate Identifier 2013-NM-013-AD; Amendment 39-17638; AD 2013-22-06 which mandates checking of upper deck ties on the 747 noting if not addressed that "We are issuing this AD to prevent widespread fatigue damage of certain fuselage upper deck tension ties, which could result in reduced structural integrity of the airplane"
 
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RE: Why Are The 380 Cabin Walls So Thick?

Sun Nov 24, 2013 3:06 pm

Quoting StTim (Reply 27):
All aircraft are subject to Airworthiness Directives.

  

This frame 56 crack must have been discovered somewhere last year because the fatigue testbed has been broken up in the beginning of 2013. The EASA requires that operators perform a one-time inspection within 4,200 flight cycles or 30,900 flight hours after an aircraft's first flight. Airbus started wing crack modification on the in service A380s with Emirates in May 2013, meaning this one-time inspection can easily be combination with the wing modification. A redesigned frame 56 is already available.
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U271437
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RE: Why Are The 380 Cabin Walls So Thick?

Tue Nov 26, 2013 5:05 pm

The answer is here: It's incredibly quiet inside: http://youtu.be/Wa3-YqOsi-E

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