Airbus A350 fuselage demo

[JF Mezei]

I found 2 images on the Airbus web site that show a prototype A350
fuselage plug. These were taken back in august 2009.

I guess the 350 isn't all vapourware anymore...

I've put a copy of the hi-res images on my site for discussion.

http://www.vaxination.ca/air/a350/

Now, onto the questions.

On both images, you can see a lot of "black dots" on the fuselage. Are
all of those individual rivets to attach the composite skin to the metal
stringers and frames inside ?

Are the amount of rivets comparable to that use on aluminium skins or
are there more or less of them ?

In the Barrel 1 picture, on the right end of the fuselage, there is a
yellow ring on the fuselage. Does this denote the extent of penetration
when another fuselage plug is mated with this one ?

It is my understanding that on the 787, the stringers are an integral
part of the skin, layed at the same time, with their shape part of the
mandrel. Shouldn't that be a major advantage since, by being an
integral part of the skin, not only are rivets not needed, but it would
also be stronger ?

Also, is it correct to state that because of all the holes needed for
rivets, they need to make the skin thicker to have the same strength as
a skin that is without holes for rivets ?

Couldn't Airbus have made the large panels with integral carbon
stringers which would have removed the need for so many rivets and only
require metal frames/ribs inside to hold the "round" shape ?

In fact, perhaps they should have made panels that spanned the length of
the plug, so only 4 panels would be needed which would have reduced the
number of joints between panels and reduced weight.

It would be interesting to get some insight on what made the 787
overweight and whether the monocoque fuselage design ended up being a
weight advantage or a liability.

I guess we'll have to wait a couple of years before we know how
overweight the 350 will be and how it will compare with the 787.
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[Uwe Klein]

JF Mezei wrote:
> I found 2 images on the Airbus web site that show a prototype A350
> fuselage plug. These were taken back in august 2009.
>
> I guess the 350 isn't all vapourware anymore...

First production wingbox ( upper or lower ) skin has been "shown" too ;-)

>
> I've put a copy of the hi-res images on my site for discussion.
>
> http://www.vaxination.ca/air/a350/
>
> Now, onto the questions.

OK, imho, afaiks and all that jazz:

>
> On both images, you can see a lot of "black dots" on the fuselage. Are
> all of those individual rivets to attach the composite skin to the metal
> stringers and frames inside ?

Looks like.

>
> Are the amount of rivets comparable to that use on aluminium skins or
> are there more or less of them ?

a lot less. When I did the guided tour in XFW I was quite surprised how
many holes you have to drill into aluminium aircraft skin to make it strong ;-)

>
>
> In the Barrel 1 picture, on the right end of the fuselage, there is a
> yellow ring on the fuselage. Does this denote the extent of penetration
> when another fuselage plug is mated with this one ?

My guess is that it is some kind of adapter ( pressurisation, other tests?)

Interface between sections ( circular cut or not ) will be the same as any
other connection between panels.

>
>
>
>
> It is my understanding that on the 787, the stringers are an integral
> part of the skin, layed at the same time, with their shape part of the
> mandrel. Shouldn't that be a major advantage since, by being an
> integral part of the skin, not only are rivets not needed, but it would
> also be stronger ?

stringers are integral to the panels too. ( looks like they reach over the panelborders )
there is a airliners.net tech_op thread on CFRP that has links to some
very nice research pdfs.

>
> Also, is it correct to state that because of all the holes needed for
> rivets, they need to make the skin thicker to have the same strength as
> a skin that is without holes for rivets ?

Have you had a look at a Dreamliner section? They are "infested" with fasteners.
for frames, internal structure, window framing, doors, ... puttied over a bit and painted
the _obviously_ visible ( forex hexheads visible ) stuff seems to be rework.

>
> Couldn't Airbus have made the large panels with integral carbon
> stringers which would have removed the need for so many rivets and only
> require metal frames/ribs inside to hold the "round" shape ?

( fine grained ) stringers seem to be integral.
See the little interstices in vertical fastener lines that fix the frames between
windows.
Horizontal fastener lines are panel borders and at the height of the internal flooring only

>
>
> In fact, perhaps they should have made panels that spanned the length of
> the plug, so only 4 panels would be needed which would have reduced the
> number of joints between panels and reduced weight.

I don't know how the final paneling will be partitioned.

But this here is a demonstrator.
It has all possibly used connecting/fastening features in a dense arrangement.

>
>
> It would be interesting to get some insight on what made the 787
> overweight and whether the monocoque fuselage design ended up being a
> weight advantage or a liability.

Hehe, who wouldn't. Airbus stated opinion was : it's a wash.
they said in airliner fuselage context panels will always have the
advantage of better process control and tolerances over a barrel for
the same purpose. A barrel thus will have to be sized for slightly higher
limits to guarantee the same certifiable integrity.

>
>
> I guess we'll have to wait a couple of years before we know how
> overweight the 350 will be and how it will compare with the 787.

Yup. But (second) guessing is fun.

can I send you some exhanced extracts from those airbus stock images? addy?

uwe