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Why Are The 380 Cabin Walls So Thick?  
User currently offlineJAAlbert From United States of America, joined Jan 2006, 1600 posts, RR: 1
Posted (11 months 1 week 6 days 7 hours ago) and read 9081 times:

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?

29 replies: All unread, showing first 25:
 
User currently offlinetrent900 From United Kingdom, joined Dec 2003, 530 posts, RR: 0
Reply 1, posted (11 months 1 week 6 days 5 hours ago) and read 9039 times:

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.


User currently offlineMax Q From United States of America, joined May 2001, 4522 posts, RR: 18
Reply 2, posted (11 months 1 week 5 days 21 hours ago) and read 8792 times:

Doesn't look all that thick, a lot of what you are seeing is insulation.


The best contribution to safety is a competent Pilot.
User currently offlinesccutler From United States of America, joined Jan 2000, 5520 posts, RR: 28
Reply 3, posted (11 months 1 week 5 days 21 hours ago) and read 8789 times:

To accommodate the spliced wires?

I kid!



...three miles from BRONS, clear for the ILS one five approach...
User currently offlineBuyantUkhaa From Mongolia, joined May 2004, 2899 posts, RR: 3
Reply 4, posted (11 months 1 week 3 days 17 hours ago) and read 8078 times:

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.


I scratch my head, therefore I am.
User currently offlineJAAlbert From United States of America, joined Jan 2006, 1600 posts, RR: 1
Reply 5, posted (11 months 1 week 3 days 3 hours ago) and read 7804 times:

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.


User currently offlineKenanC From United States of America, joined Aug 2013, 191 posts, RR: 0
Reply 6, posted (10 months 2 weeks 6 days 6 hours ago) and read 6407 times:
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Wish they could use all that extra space to make the seats wider... lol.


Flown: A319/20/21/33/43/88 B737/38/39/52/63/72/7W ERJ135/40/45 CRJ200 ATR42
User currently onlineprebennorholm From Denmark, joined Mar 2000, 6451 posts, RR: 54
Reply 7, posted (10 months 2 weeks 6 days 1 hour ago) and read 6257 times:

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.


Always keep your number of landings equal to your number of take-offs, Preben Norholm
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17040 posts, RR: 66
Reply 8, posted (10 months 2 weeks 6 days ago) and read 6231 times:

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.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinebikerthai From United States of America, joined Apr 2010, 2131 posts, RR: 4
Reply 9, posted (10 months 2 weeks 5 days 3 hours ago) and read 5889 times:

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



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 10, posted (10 months 1 week 2 days 10 hours ago) and read 5068 times:

It does not look more thicker than other types in the pic.....why do you say so?.


Think of the brighter side!
User currently offlineDUSint From Germany, joined Apr 2013, 194 posts, RR: 0
Reply 11, posted (10 months 1 week 2 days 8 hours ago) and read 5006 times:

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


User currently offlineWingedMigrator From United States of America, joined Oct 2005, 2213 posts, RR: 56
Reply 12, posted (10 months 1 week 2 days 1 hour ago) and read 4853 times:

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.


User currently offlineCALTECH From Poland, joined May 2007, 2237 posts, RR: 26
Reply 13, posted (10 months 6 days 4 hours ago) and read 4353 times:

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.



UNITED We Stand
User currently offlinezeke From Hong Kong, joined Dec 2006, 9103 posts, RR: 75
Reply 14, posted (10 months 5 days 20 hours ago) and read 4228 times:

Quoting CALTECH (Reply 13):

The AD refers to one fitting on one frame found during fatigue testing.



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlineCALTECH From Poland, joined May 2007, 2237 posts, RR: 26
Reply 15, posted (10 months 3 days 1 hour ago) and read 3804 times:

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.



UNITED We Stand
User currently offlinebikerthai From United States of America, joined Apr 2010, 2131 posts, RR: 4
Reply 16, posted (10 months 2 days 22 hours ago) and read 3770 times:

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

bt



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlineMax Q From United States of America, joined May 2001, 4522 posts, RR: 18
Reply 17, posted (10 months 2 days 19 hours ago) and read 3742 times:

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.



The best contribution to safety is a competent Pilot.
User currently offlinezeke From Hong Kong, joined Dec 2006, 9103 posts, RR: 75
Reply 18, posted (10 months 2 days 17 hours ago) and read 3717 times:

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 ???



We are addicted to our thoughts. We cannot change anything if we cannot change our thinking – Santosh Kalwar
User currently offlinebikerthai From United States of America, joined Apr 2010, 2131 posts, RR: 4
Reply 19, posted (10 months 2 days 10 hours ago) and read 3628 times:

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



Intelligent seeks knowledge. Enlightened seeks wisdom.
User currently offlineWingedMigrator From United States of America, joined Oct 2005, 2213 posts, RR: 56
Reply 20, posted (10 months 2 days ago) and read 3530 times:

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.


User currently offlineCALTECH From Poland, joined May 2007, 2237 posts, RR: 26
Reply 21, posted (10 months 1 day 11 hours ago) and read 3413 times:

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.



UNITED We Stand
User currently offlineDUSint From Germany, joined Apr 2013, 194 posts, RR: 0
Reply 22, posted (10 months 1 day 11 hours ago) and read 3396 times:

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...


User currently offlineCALTECH From Poland, joined May 2007, 2237 posts, RR: 26
Reply 23, posted (10 months 1 day 10 hours ago) and read 3384 times:

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.



UNITED We Stand
User currently offlinebikerthai From United States of America, joined Apr 2010, 2131 posts, RR: 4
Reply 24, posted (10 months 1 day 7 hours ago) and read 3349 times:

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



Intelligent seeks knowledge. Enlightened seeks wisdom.
25 Post contains links CALTECH : One can see where Frame 56 is located. http://blogs.crikey.com.au/planetalk...g/files/2010/11/page-9-600x328.jpg
26 WingedMigrator : So frame 56 is at the rear wing spar.
27 StTim : All aircraft are subject to Airworthiness Directives. For instance a quick scan finds Docket No. FAA-2013-0625; Directorate Identifier 2013-NM-013-AD;
28 Post contains images KarelXWB : 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 r
29 Post contains links U271437 : The answer is here: It's incredibly quiet inside: http://youtu.be/Wa3-YqOsi-E
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