ferpe
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 7:08 am

I felt we needed such a thread now that the prototype production of the A350 starts in earnest. I have made this first post free of debate just to get the thread started, for clarity of the process I have posted the assembly process here:

A350 fuselage production
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ferpe
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 7:31 am

The first post will be about signs of a delay, something I have wondered about since Flightblogger showed this piece about the Spirit section 15 delivery. This is the center section and the one you start with at the FAL:

http://www.flightglobal.com/blogs/fl...irst-spirit-a350-parts-to-hea.html

Now the other pieces of this center section have already been delivered to Airbus St Nazaire integration plant (the wingbox, the keel beam and the MLG bay) mid August, why are these panels delivered end October?

Here the panels on the CFRP and ALU (lower sections) frames in section 15:
Big version: Width: 500 Height: 281 File size: 101kb
A350 section 15


Before Spirit have put them together and wheeled them over to the Airbus plant nearby we are mid November. There these pieces will be mated with the center wingbox, the keel beam and the MLG well

(here those pieces shown in the frames of section 15 Smile
Big version: Width: 600 Height: 399 File size: 43kb
A350 center section details


and then the dark blue panels will be put on to form the famous side-of-body joint to the wingbox.

Now in the update that came today Ostrower confirms this means a delay to FAL, why? I don't want to blame Spirit but why have such pretty straight forward parts like the skin panels be late? Or is it the more intrinsic dark blue panels that are the cause of the delay, we know that A has been studying the side-of-body joint extra carefully even thought is it modeled after the A380 join.

Note:
This excellent article about the composite manufacture of section 15:

http://www.compositesworld.com/artic...350-xwb-update-smart-manufacturing

reveals that the chart in post 1 is a bit simplified, to my understanding the Spirit assembled section 15 (frames, floor grid, side and upper panels) is wheeled over to the Aerolia (Airbus) St Nazaire plant for mating with wingbox, keel-beam and MLG bay and then get stuffed with systems there (the first is for the structure test frame ie no systems). If the wheeling over happens later this year we indeed have a delay or Aerolia are very fast with the mating and shipping.

[Edited 2011-10-26 00:43:51]
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dynamicsguy
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 9:58 am

To add another link: Horizontal stabiliser assembly begins

Quoting ferpe (Reply 1):
I don't want to blame Spirit but why have such pretty straight forward parts like the skin panels be late?

That's a pretty easy comment to make from the outside. Even "straight forward" assemblies have a great deal of design and analysis behind them, production to get right and a mountain of paperwork.
 
JerseyFlyer
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 10:22 am

The composites world article referenced in Reply 1 is indeed excellent, and makes clear that the "ribs and panels" approach should not necessarily be seen as second best compared to barrels (a la 787), as it has its own clear advantages.

It will be interesting to see how these two approaches work out in practice and whether one becomes the "standard" for future aircraft programmes as a result.
 
ferpe
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 10:58 am

Quoting dynamicsguy (Reply 2):
Even "straight forward" assemblies have a great deal of design and analysis behind them, production to get right and a mountain of paperwork.

Here you are right in the sense that section 15 is the most critical part of the airplane. The forces from the wings, the MLG and the tube all come together here. Now the rechecking of all these things before release of the drawings (models really in modern CAD) could be the reason, a late QA failure of a panel could also be the cause. Fact is, it seems the shipping of the Spirit parts are late compared to the rest of the section 15 components.

[Edited 2011-10-26 04:13:15]
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Stitch
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 12:02 pm

I would think we'd of heard of any QA failures in a panel. Spirit is the only 787 sub with their act together, so I'm inclined to follow dynamicsguy line of thought that Airbus was tweaking the design for this section and that pushed back fabrication. Airbus have stated that they had to make changes to the electrical structure network for lightning and radio frequency interference protection and that was part of what's pushed the original schedule back about six months.

[Edited 2011-10-26 05:04:19]
 
ferpe
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 12:28 pm

Quoting Stitch (Reply 5):
Airbus have stated that they had to make changes to the electrical structure network for lightning and radio frequency interference protection and that was part of what's pushed the original schedule back about six months.

That would have delayed the rear and forward fuselages as well and those we have seen in a more complete state then section 15. I think it's more probable they checked the wing to body join once more (which they also have stated they have done) this would be singular to section 15 and Spirit would have no part in such a delay. Anyway it is the first concrete sign that things are getting late, somehow A started back-pedaling on MSN01s assembly time about a month ago (Enders preparing the world that delays would be better then jams) while they where all singing the tune of being on time at Paris in June, something have happened during/after the summer IMHO.

Wonder what    .

[Edited 2011-10-26 05:33:32]
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mwhcvt
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 12:54 pm

Why no mention of where the wings are made   I guess it's not going to be flying all that far   

Matt
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ferpe
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 2:31 pm

Quoting MWHCVT (Reply 7):
Why no mention of where the wings are made

Being from UK I understand your grief    , it was simple I did not have this picture in my library because it was to large, here the wing construction flow:

http://i298.photobucket.com/albums/m...pe_bucket/A350_Wing_production.jpg

Now the wings come to the FAL after section 15 therefore the focus on that part    .
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 3:11 pm

Quoting ferpe (Reply 1):
I don't want to blame Spirit but why have such pretty straight forward parts like the skin panels be late?

No part on a brand-new airliner using an entirely new construction method is straightforward... obviously we hope for no delays, but delays are hardly surprising.
 
mwhcvt
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 3:27 pm

Quoting ferpe (Reply 8):
Being from UK I understand your grief , it was simple I did not have this picture in my library because it was to large, here the wing construction flow:

:D I was to some extent having a bit of jest  but it's really interesting to see the process so thanks for putting it together  

Matt
Must think up a new one soon, slow moving brain trying to get into gear ;)
 
astuteman
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 3:56 pm

Quoting seabosdca (Reply 9):
No part on a brand-new airliner using an entirely new construction method is straightforward... obviously we hope for no delays, but delays are hardly surprising.

It's also easy for us to forget how delays to one programme can impact another - e.g. engineeering resource that has been funnelled into the A400M and A380 to resolve unforseen issues, could have been progressing the A350.
We know the A350 has been impacted by this...   

Rgds
 
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 4:01 pm

Quoting ferpe (Reply 1):
Here the panels on the CFRP and ALU (lower sections) frames in section 15:

When seeing this picture I realized that Airbus did actually change its design philosophy for the rear section: the upper edge of the tail section declines slightly (a la 767, 787) whereas the tail sections of the A 300, A 310, A 330 / 340 had a straight upper edge.


View Large View Medium
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Photo © Tommy Desmet Photography

 
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EPA001
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 4:07 pm

Quoting ferpe (Thread starter):
I felt we needed such a thread now that the prototype production of the A350 starts in earnest

This is a nice initiative ferpe. I guess with the first prototype being assembled this will be an interesting thread to follow. Thanks for your effort.  
Quoting astuteman (Reply 11):
We know the A350 has been impacted by this...   

Yes we do. But so far any envisioned delay still looks oversee-able. Let's hope it will stay like that when more pieces of the puzzle are put together.

[Edited 2011-10-26 09:08:14]
 
Aircellist
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 7:34 pm

Quoting N14AZ (Reply 12):
When seeing this picture I realized that Airbus did actually change its design philosophy for the rear section: the upper edge of the tail section declines slightly (a la 767, 787) whereas the tail sections of the A 300, A 310, A 330 / 340 had a straight upper edge.

I had observed the same thing... What would be the advantage of either construction?
"When I find out I was wrong, I change my mind. What do you do?" -attributed to John Maynard Keynes
 
babybus
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 8:05 pm

Quoting MWHCVT (Reply 7):
Why no mention of where the wings are made

I think you'd have to admit that even the UK doesn't make a song and dance about producing the wings. Most people don't know they do.

The UK government needs to find some way to make even more parts for future Airbus planes, if they have their head screwed on. It's all jobs for people.

Quoting ferpe (Reply 1):
ferpe

I really like those diagrams. Great stuff.
and with that..cabin crew, seats for landing please.
 
747400sp
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 8:08 pm

This thing is going to look like an Airbus 777.
 
N14AZ
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 8:41 pm

Quoting aircellist (Reply 14):
What would be the advantage of either construction?

Well, if somebody would wake me up in the middle of the night, screaming at me to build a tail section then I would pray it would be for an A 300 / 310 / 330.   I think the old Airbus-style tail section is easier in terms of construction but has eventually aerodynamic disadvantages. Maybe a real expert can explain this.

Quoting 747400sp (Reply 16):
This thing is going to look like an Airbus 777.

That's what I thought as well.

@ Ferpe: thanks for starting this thread. Will be interesting to follow.
 
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 9:09 pm

Hey, N14AZ, wake up and build a tail section, please!
"When I find out I was wrong, I change my mind. What do you do?" -attributed to John Maynard Keynes
 
XT6Wagon
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 9:26 pm

Quoting JerseyFlyer (Reply 3):
The composites world article referenced in Reply 1 is indeed excellent, and makes clear that the "ribs and panels" approach should not necessarily be seen as second best compared to barrels (a la 787), as it has its own clear advantages.

Its an amazing puff peice, that is, its nearly word for word airbus's own statements on why they went to panels.

Its great that you can talior the panels with thickness and direction of the fibers. Strangely they keep ignoring that Boeing does THE VERY SAME THING in the barrels.

Also I have to laugh at the text that "we are using smaller parts to make assembly and repair cheaper and easier" right next to a photo of the A350 top wingskin that is a single huge item.
 
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 9:46 pm

Quoting MWHCVT (Reply 7):
Why no mention of where the wings are made I guess it's not going to be flying all that far

I was wondering the same thing too. We know that some aircraft like Twin otters can almost fly with no wings as they are so robust, but I don't know about Airbus.... Maybe they are working towards that. I guess it does not quite need any landing gear either.

Quoting N14AZ (Reply 12):
When seeing this picture I realized that Airbus did actually change its design philosophy for the rear section: the upper edge of the tail section declines slightly (a la 767, 787) whereas the tail sections of the A 300, A 310, A 330 / 340 had a straight upper edge.

well, that change began with the A380...

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Photo © Csaba Király



(unlike what AF and SQ apparently want us to believe...)

View Large View Medium
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Photo © Remi Dallot


View Large View Medium
Click here for bigger photo!

Photo © Karl K.

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ferpe
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 9:56 pm

Quoting XT6Wagon (Reply 19):
Its an amazing puff peice, that is, its nearly word for word airbus's own statements on why they went to panels.

I have actually read the NASA study from some 20 years ago, it marvels over that you can use 4 panels to cover a DA barrel (instead of many more panels on metal ships). B actually did the fuselage part (and drew those conclusions) and McAir the wing study. IMHO the world has moved on since then and Bs single piece barrels have advantages (and disadvantages). A has chosen a more conservative approach as they did with staying with bleed. We will know in 10 years who did the sensible choice, I don't think the panel approach is more technically advanced or elegant however.

If A manages to keep the 350 program delays in months instead of years that might be thee    good reason for going a bit conservative.

As Albaugh said "we just booted it", that is another way to do things, cost a $ or two however    .
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lhrnue
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A350 Prototypes Production Thread Part 1

Wed Oct 26, 2011 11:06 pm

Why are the wings going from UK to Germany and not directly to France? Does not look like a cost effective process to me.
 
ferpe
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A350 Prototypes Production Thread Part 1

Thu Oct 27, 2011 4:44 am

Quoting lhrnue (Reply 22):
Why are the wings going from UK to Germany and not directly to France? Does not look like a cost effective process to me.

The A competence center for high-lift devices is in Bremen, they have tested the slats, flaps, spoilers, ailerons in a full scale test rig there. They therefore have all the knowledge how to install these and how they should be QAd, they also fit all the wing plumbing there. What goes to FAL is a complete functional wing, Brougthon only does the structure.
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XT6Wagon
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A350 Prototypes Production Thread Part 1

Thu Oct 27, 2011 6:22 am

Quoting ferpe (Reply 21):
IMHO the world has moved on since then and Bs single piece barrels have advantages (and disadvantages). A has chosen a more conservative approach

I know, I was just saying that this "new" report was nothing of the kind, and lacked relevant info.

I fully agree that Airbus made the right call not trying to pull barrels out of thier hat for the A350. That doesn't mean its the massively awesome decision and Boeing is a pile of retards like Airbus' claims about thier technology. Its simply a risk/reward decision where Airbus had little time to evaluate how to mitigate the huge risks, and saw the reward as not being one that results in a major advantage at the sales discussion. Same with bleed vs bleedless. Risk vs reward clearly favored using the low risk method even at the risk of some technical downsides.

Both choices are hardly on the level of Piston Vs turbojet, or Turbojet vs TurboFan. More along the lines of "winglets or no winglets" for narrowbodies have been till recently.
 
ferpe
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A350 Prototypes Production Thread Part 1

Thu Oct 27, 2011 12:14 pm

Quoting XT6Wagon (Reply 24):
I know, I was just saying that this "new" report was nothing of the kind, and lacked relevant info.

That was my implicit message as well, the report had one point however, panels does allow you to use different constructions techniques between the panels. In the study they used a sandwich panel for the keel area for instance. As no-one has opted to do anything but normal tape-layup skins this capability is not used, further panels would enable co-curing of the frames. A use neither possibility, therefore their talk about panels being a "better" technology shall be taken with a grain of salt IMHO, less risk and more flexible for fixing issues yes, but "better" don't think so.
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tdscanuck
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A350 Prototypes Production Thread Part 1

Thu Oct 27, 2011 2:43 pm

Quoting ferpe (Reply 25):
the report had one point however, panels does allow you to use different constructions techniques between the panels.

So does barrels...there's nothing to prevent you from laying sandwich core into parts of the barrel during the layup process.

Tom.
 
kl911
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 8:44 am

Great, I was waiting for this Thread. The A350 will be the plane of the future with all this new technology and materials.

Does Airbus have a timeline for first flight?
 
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 9:35 am

Quoting kl911 (Reply 27):
The A350 will be the plane of the future with all this new technology and materials.

True, but it will not be the only plane of the future.  .
 
SEPilot
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 11:21 am

The difference between barrels and panels masks what the real issue is, and that is joints. In any structure joints are usually the weak point, and they require reinforcement to carry the required loads. In bridges and buildings this is a non-issue as weight is of minor importance, but in aircraft it is of supreme importance, and hence anything that reduces the number of joints is generally desirable. Ideally the perfect aircraft would be formed in one piece, wings, fuselage, and empennage included, but the technology to do this is not yet available. It is also important to recognize that all joints are not created equal; in a pressure vessel the circular joints have much less stress than horizontal ones. But there are other factors to be considered, including manufacturing issues and cost, and so while the barrel approach is theoretically better it does have its problems, and the ultimate question is which one will produce a better plane, and the definition of that is which one will make more money for its operators while maintaining a near perfect safety record. We will have to wait for both the A350 and 787 have been flying for some time to see.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
AustrianZRH
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 11:36 am

Quoting SEPilot (Reply 29):
in a pressure vessel the circular joints have much less stress than horizontal ones

Isn't it the other way round, more stress on the circular joints compared to the horizontal joints?
WARNING! The post above should be taken with a grain of salt! Furthermore, it may be slightly biased towards A.
 
astuteman
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 12:19 pm

Quoting SEPilot (Reply 29):
The difference between barrels and panels masks what the real issue is, and that is joints

The "Real" Issue? There are a plethora of real issues, of which joints is one...

Quoting SEPilot (Reply 29):
But there are other factors to be considered, including manufacturing issues and cost,

As you say....

Quoting SEPilot (Reply 29):
in a pressure vessel the circular joints have much less stress than horizontal ones.

For a simple unstiffened pressure vessel perhaps.
My experience of internally stiffened pressure vessels, that also have many structural or attachment interfaces, suggests that the real picture isn't as simple as that.
The frames, and stringers, which are required whatever approach is taken, modify the way the skin, and skin joints, experience stresses, and are designed to do so.

Quoting SEPilot (Reply 29):
while the barrel approach is theoretically better it does have its problems

Theoretically better in respect to what? The "problems" are just as easily predicted in theory, and must surely constitute part of the "goodness" of the solution

It's frustrating to hear pundits (on either side of the argument) claiming that one approach is "better" than the other. In most cases they are making that claim based on a single parameter out of dozens, possibly hundreds, which determine the "goodness" of the solution.
I also read about "technological advancement" and "risk" and I'm equally puzzled by the digitality of the arguments there too.
If we consider
materials technology
Tape laying technology
Computer Control technology

Which is more advanced? I'd venture to suggest that the 787 and A350 are about on a par on all of these.

Barrel vs Panel?
To me that's not a function of the "technological advancement" measured by parameters such as the ones above.

It's nothing more than a preferred method of product handling, neither of which break any new "technological" ground except the extent to which BOTH apply computer control and programming to the accuracy of handling the product during the application of new material.
Mandrels and barrels have been around for centuries.

Are panels heavier because of the joints? Probably.
How much heavier do they make the airframe overall? 200kg? 250kg?
Pick your own number.
What effect does that have on the economics of the aircraft if it is factored into the design at the outset?
I'd venture to suggest that the impact is er, small.

Are panels easier to manipulate? Probably.

Which one is "theoretically better" for building an aircraft out of?
If you know the answer to that, then I must confess to being way less smart than those that know.
Because I don't.

Quoting SEPilot (Reply 29):
the ultimate question is which one will produce a better plane

For all the debate, do you know what? I think that other factors will have much bigger roles to play on "which is the better plane" than barrels v panels.

As a couple of examples...

I happen to believe for example, that the extra 5" of cabin width on the 787 compared to the A330 is actually a greater advantage to the 787 than its CFRP fuselage (what would improve the A330's competitiveness more, an extra 5" on diamter, or CFRP barrel fuselage?).
For some, possibly many carriers, it can leverage an 12% operating revenue advantage right out of the hat, completely dwarfing any financial gain a CFRP barrel can possibly bring. Just an opinion

In other cases, the A350 family being placed in the market at a larger size than the 787 make well work to it's ADVANTAGE in some cases, and DISADVANTAGE in others.
It's easy to imagine that such considerations may dwarf the "barrels" v "panels" debate in many cases.

Still, this rich picture of variables does allow for a fascinating spectrum of views and opinions, doesn't it  

Rgds
 
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EPA001
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 12:28 pm

Quoting astuteman (Reply 31):
Still, this rich picture of variables does allow for a fascinating spectrum of views and opinions, doesn't it  

And that is what keeps us busy here. Thanks for another great post BTW.  
 
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 12:30 pm

Fred

Quoting SEPilot (Reply 29):
and the definition of that is which one will make more money for its operators while maintaining a near perfect safety record

Surely it is the one that makes more money for the manufacturer?

Fred
Image
 
SEPilot
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 12:59 pm

Quoting astuteman (Reply 31):
For a simple unstiffened pressure vessel perhaps.
My experience of internally stiffened pressure vessels, that also have many structural or attachment interfaces, suggests that the real picture isn't as simple as that.
The frames, and stringers, which are required whatever approach is taken, modify the way the skin, and skin joints, experience stresses, and are designed to do so.

Actually, your experience is with a pressure vessel subject to primarily external rather than internal pressure. That will behave very differently. Also, I presume you are dealing primarily with welded joints, whereas in CFRP construction we are talking with making as few joints as possible. My point is that a cylindrical pressure vessel with internal pressurization will experience much greater hoop stress around its circumference than tensile stress along its length. Every picture I have seen of a burst pressure vessel exhibits the fact that it always splits parallel to its length unless there is a weakness elsewhere. Yes, there are other factors in building either an aircraft fuselage or a submarine, but this is basic physics that will not go away.

Quoting astuteman (Reply 31):
Theoretically better in respect to what? The "problems" are just as easily predicted in theory, and must surely constitute part of the "goodness" of the solution

See explanation above. Nothing will change the fact that the lengthwise joints will see greater stress than the vertical ones.

Quoting astuteman (Reply 31):

Which is more advanced? I'd venture to suggest that the 787 and A350 are about on a par on all of these.

On this I completely agree. And we will see once they are in service which one was better executed. That, in the end, will have a bigger effect than the theoretical advantage of barrels over panels.

Quoting flipdewaf (Reply 33):
Surely it is the one that makes more money for the manufacturer?

I will accept that. However, I am expecting that the one that makes the most money for its operators will also make the most for its manufacturer. However, this is not guaranteed.

To get back to the panels vs. barrels issue, my approach in designing anything is to start by trying to optimize the most basic elements using fundamental principles;for example, if rigidity is required, use triangular rather than rectangular structures; use as few bends in structural elements as possible, and use as few joints as I can. Operational and manufacturing requirements always enter in and usually degrade the optimum structure, but the closer I can stay with it and find ways to keep the optimum structure the better the solution usually is. One of my engineering maxims is that it takes a lot of thought to make things simple, and almost always the simpler the solution the better it is. That is why I have been such a vocal advocate of barrels vs. panels; I do not design aircraft, and there are a lot of issues with which I have no familiarity, but the fundamental issue that joints on the circumference are more problematic than joints around it is not subject to debate. But the difference in practice may not be large; as Astuteman notes the actual weight difference will be quite small in relation to the overall weight, and manufacturing considerations may make it worthwhile to accept that penalty.

[Edited 2011-10-28 06:12:50]
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
art
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 1:01 pm

Quoting flipdewaf (Reply 33):
Quoting SEPilot (Reply 29):
and the definition of that is which one will make more money for its operators while maintaining a near perfect safety record

Surely it is the one that makes more money for the manufacturer?

A product that makes more money for its users can be sold for a higher price by the manufacturer? Symbiotic, I guess: manufacturer makes more money; user makes more money.
 
astuteman
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 1:23 pm

Quoting SEPilot (Reply 34):
Actually, your experience is with a pressure vessel subject to primarily external rather than internal pressure

It would be dangerous of you to assume that all of my pressure vessel experience has been with externally pressurised vessels.....   

Quoting SEPilot (Reply 34):
Every picture I have seen of a burst pressure vessel exhibits the fact that it always splits parallel to its length unless there is a weakness elsewhere

Every picture I've seen of a burst pressure vessel (and I've seen thousands) has been of an unstiffened vessel.
The fact that the frames support the skin is basic physics that will not go away.


Quoting SEPilot (Reply 34):
See explanation above

But the explanation above only considered one parameter under the blanket heading of "better".
That one parameter on its own doesn't mean that the barrel solution is "better" overall   

Rgds
 
SEPilot
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 1:35 pm

Quoting astuteman (Reply 36):
It would be dangerous of you to assume that all of my pressure vessel experience has been with externally pressurised vessels.....

I accept the fact that that is the only one with which I am familiar. I do not know anything about your prior experience.

Quoting astuteman (Reply 36):
Every picture I've seen of a burst pressure vessel (and I've seen thousands) has been of an unstiffened vessel.
The fact that the frames support the skin is basic physics that will not go away.

Yes, the frames support the skin. But the forces on the vessel are such that there is greater force tending to split the skin along the length of the cylinder than perpendicular to its axis. Frames and other reinforcements are installed to counteract that, and they contribute weight as well as strength. The goal is to make the lightest possible structure that is able to withstand the loads and have acceptable life. My point remains; it is easier to do so if you can avoid joints parallel to the axis and only have them perpendicular to it. It is the same as making a rigid structure; you can do it with rectangular framing, but it is much easier with triangular.

There is a similar issue in internal combustion engine design. The cylinder head to cylinder joint is one of the most problematic, and the best solution is either remove it completely or make it permanent (as with air cooled aircraft engine cylinders.) The only engine I know that eliminated it completely was made by Bugatti in the 30's; this is the ideal solution but had so many manufacturing and service problems than nobody else that I know of has adopted it. I have heard of aircraft cylinders parting company with their heads (I nearly had one on my airplane; when discovered it was cracked about halfway around), but I have never heard of a Bugatti losing cylinder head integrity. But there weren't all that many of them made. Anyway, the issue of barrels vs. panels may prove similar; the theoretically optimum solution of barrels may prove enough more expensive in the long run to be less desirable. We will see.

[Edited 2011-10-28 06:41:18]
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
astuteman
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 1:54 pm

Quoting SEPilot (Reply 37):
this is the ideal solution but had so many manufacturing and service problems than nobody else that I know of has adopted it

Which perhaps suggests that the "ideal" solution wasn't necessarily that "ideal" ?     

Hence my emphasis on differentiating between "better" in reference to a particular parameter, versus "better" overall

Rgds
 
SEPilot
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 2:12 pm

Quoting astuteman (Reply 38):
Which perhaps suggests that the "ideal" solution wasn't necessarily that "ideal" ?

Hence my emphasis on differentiating between "better" in reference to a particular parameter, versus "better" overall

What we are disputing is theoretical vs. practical. The barrel approach is clearly superior theoretically; however, when it comes to actually building an aircraft that will be the most efficient and require the least maintenance it is not assured that that approach will yield the best solution. I do believe that it will, but we have a nearly ideal comparison case here to see whether or not it will. I will agree that Boeing and Airbus have equally good engineers and available technology; one has taken one approach and the other has taken the other; Airbus does have a slight advantage in being a few years behind giving them access to any new developments that Boeing missed. We will see how the planes compare once both of them are flying; I do expect them both to be excellent. The fact that they do not really compete head to head will muddy the waters somewhat, however.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
astuteman
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 2:48 pm

Quoting SEPilot (Reply 39):
What we are disputing is theoretical vs. practical.

Or perhaps more accurately, purely product performace benefit vs overall lifecycle benefit...

Either way, if as I suspect, we both pretty much know what the other means, the debatetends to take on a somewhat pedantic flavour.

Quoting SEPilot (Reply 39):
I do expect them both to be excellent

  

Looking forward to seeing them both in action

Rgds
 
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kanban
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 5:16 pm

Quoting astuteman (Reply 31):
The "Real" Issue? There are a plethora of real issues, of which joints is one...


This may be one of the bigger problems they will face, especially if weight becomes an issue.

Quoting lhrnue (Reply 22):
Why are the wings going from UK to Germany and not directly to France? Does not look like a cost effective process to me.


I have concerns that the amount of sub-assembly movement all over the continent will in the end be a detrimental logistics load that will handicap efficient production processes.. Although computer design of parts and tooling will minimize mis-fits, there appear to be too many hands stirring the pot. There will be a huge investment in sub assembly transportation tooling costs, a huge transportation cost, and a gap between the point a problem is found and the point it originated necessitating a complex multi company/site repair/rework plan.
 
astuteman
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 5:55 pm

Quoting kanban (Reply 41):
I have concerns that the amount of sub-assembly movement all over the continent will in the end be a detrimental logistics load that will handicap efficient production processes

Although they do by-and-large seem to have confined sub-assembly moves to one half of one continent..  

Rgds
 
bigsmile
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A350 Prototypes Production Thread Part 1

Fri Oct 28, 2011 6:06 pm

Quoting lhrnue (Reply 22):
Why are the wings going from UK to Germany and not directly to France? Does not look like a cost effective process to me
Quoting ferpe (Reply 23):
The A competence center for high-lift devices is in Bremen, they have tested the slats, flaps, spoilers, ailerons in a full scale test rig there. They therefore have all the knowledge how to install these and how they should be QAd, they also fit all the wing plumbing there. What goes to FAL is a complete functional wing, Brougthon only does the structure.

A318/19/20/21 (Single Aisle) Complete Functional Wing when leaves Broughton.

A330/340/350 (Twin Aisle) 20% Functional Wing (Secondary Structure, Fuel and Hydraulic Systems)

A380 Fully Equipped Wing, less flying controls (Fitted in Toulouse) due to transportation.

It comes down to Politics at the end of the day.the way the work is given to various Countries.
 
ferpe
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A350 Prototypes Production Thread Part 1

Sun Oct 30, 2011 8:51 pm

Here the section 15 crown panel as it reached Spirit St Nazaire. One can see it's impressive size when one compares to the men on the right hand side:

http://i298.photobucket.com/albums/m...rpe_bucket/Section15crownpanel.jpg
Non French in France
 
Semaex
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A350 Prototypes Production Thread Part 1

Mon Oct 31, 2011 3:12 am

Quoting bigsmile (Reply 43):
It comes down to Politics at the end of the day.the way the work is given to various Countries.

... or resources for that matter. If Broughton is already busy with 19/20/21, and that's the core of the Airbus business, then it might just be a smart decision to put off more workload to a different station.

Maybe someone from the inside can enlight us..?
// You know you're an aviation enthusiast when you look at your neighbour's cars and think about fleet commonality.
 
WingedMigrator
Posts: 1767
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A350 Prototypes Production Thread Part 1

Mon Oct 31, 2011 5:27 am

Quoting ferpe (Reply 44):
Here the section 15 crown panel as it reached Spirit St Nazaire

Is that the flag of St-Nazaire in the background?   No matter, that's a huge part.
 
WingedMigrator
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A350 Prototypes Production Thread Part 1

Mon Oct 31, 2011 5:35 am

Quoting SEPilot (Reply 34):
the actual weight difference will be quite small in relation to the overall weight

All the more so because an airliner fuselage is far from a cylindrical pressure vessel, featuring all manner of penetrations and structural reinforcements. Here is a shot of a pristine 787 barrel:

787 windows
 
dynamicsguy
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A350 Prototypes Production Thread Part 1

Mon Oct 31, 2011 7:44 am

Quoting ferpe (Reply 44):
Here the section 15 crown panel as it reached Spirit St Nazaire.

Why do they never publish photos showing the interesting side of these A350 panels?
 
astuteman
Posts: 6340
Joined: Mon Jan 24, 2005 7:50 pm

A350 Prototypes Production Thread Part 1

Mon Oct 31, 2011 8:40 am

Quoting WingedMigrator (Reply 47):
All the more so because an airliner fuselage is far from a cylindrical pressure vessel, featuring all manner of penetrations and structural reinforcements

Which was the exact point I was hoping to get across   

Quoting dynamicsguy (Reply 48):
Why do they never publish photos showing the interesting side of these A350 panels?

Proprietary Information?

Rgds

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