Discussion:
Airbus considers all composite fuselage
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A Guy Called Tyketto
2006-11-06 20:19:48 UTC
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http://seattlepi.nwsource.com/business/291097_airbus04.html

Airbus considers composite fuselage

Saturday, November 4, 2006

By JAMES WALLACE
P-I AEROSPACE REPORTER

In what would be a radical change of course for the company, Airbus may
switch to a composite fuselage for its next new jetliner.

It would mark the sixth time that Airbus has changed plans as it
scrambles for the right airplane to not only challenge The Boeing Co.'s
787 Dreamliner but possibly leapfrog the 777. The two Boeing planes are
dominating sales for jets that seat from about 250 to 350 passengers.

Airbus may present its latest A350 design to the board of its parent
company, EADS, next week, according to a published report.

"If they are reconsidering the virtues of an all-composite tube
(fuselage), that's a smart exercise," said Richard Aboulafia, vice
president of analysis for the Teal Group, an industry consulting firm
near Washington, D.C.

"They have to decide whether they believe composites is a killer
technology," Aboulafia said. "If they believe that it is, then a
metal-tubed A350 would be ambushed eventually by a 777 composite
replacement."

Airbus has said it would aim the A350 at not only the 787 but the 777,
a bigger plane that seats from 300 to 360 passengers, depending on the
model.

Boeing's two-engine 777 has been dominating sales for jets its size the
past few years. Airlines prefer it over the four-engine Airbus A340,
which is less fuel-efficient and has a smaller cabin.

The older 777 has an aluminum fuselage, but a composite tail. The new
787 will be the world's first large passenger jet with an all-composite
airframe, including fuselage. Boeing believes composites are the future
of commercial jet making and has said it has made its last aluminum
jetliner. Composites are stronger and lighter than metal and do not
corrode. Among other benefits, the composite fuselage of the 787 will
save airlines on maintenance and give passengers an improved cabin
environment, according to Boeing.

Airbus, on the other hand, has said Boeing is pushing the technology
envelope too far with the 787.

Earlier this year, Airbus redesigned the A350 after criticism from
several airline and industry executives that its proposed plane would
not be competitive against the 787.

At the Farnborough International Airshow in England in July, Airbus
unveiled the redesigned jet, dubbed the A350 XWB (extra wide body).
Airbus said then that the A350 would have a composite wing, but not a
composite fuselage. Airbus said it would develop three versions of the
A350, the first of which would not be ready for airline service until
2012.

But last week, Tim Clark, president of Emirates, an important Airbus
customer, told reporters that the A350 XWB was still lacking.

"It has to do better than that," he said of Airbus.

Emirates has been considering either the A350 or 787 as it looks to
place an order for as many as 100 midsize jets.

Two weeks ago, the respected online industry publication Air Transport
World reported that Airbus was rethinking the A350 design to include a
composite fuselage. It quoted "key" unnamed customers as telling Airbus
that it had not yet done enough with the plane to combat the 787.

Bloomberg News reported Friday that Airbus has indeed decided to
redesign the A350 to include more composite and will present the new
design to the EADS board Tuesday. Bloomberg, quoting two unnamed
sources, said the latest redesign will push the development costs of
the A350 from $10 billion up to $12 billion. The changes will delay the
jet's entry into service until at least 2013, Bloomberg quoted the
sources as saying.

Boeing plans four versions of its 787, the first of which will enter
service in 2008.

The European Aeronautic Defense and Space Co., the world's
second-largest aerospace company after Boeing, has not yet approved
development of the A350. It has its hands full trying to repair the
damage from a series of embarrassing delays in the A380 program. EADS
executives recently said they wanted to make sure there are enough
engineers, and that EADS has the financial resources, to develop the
A350, given the full-court press at Airbus to get the A380 problems
fixed.

Industry analysts believe Airbus must develop the A350 or concede the
important middle of the jetliner market to Boeing and its 787.

In his recent comments to reporters, Clark, the Emirates Airlines
executive, said if Airbus does not come up with a competitive plane to
counter Boeing's 787, "they'll be out of business."

The Boeing jet has racked up more than 400 firm orders even though the
Dreamliner won't make its first test flight until next summer.

BL.
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Daniel
2006-11-06 22:12:54 UTC
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There had been rumors about such a move 2 months ago with Airbus
contacting tooling manufacturers. Finmeccanica in Italy, which does 787
fuselage sections has expressed interest in participating to the A350
project. Achieving the 2012 target date might still be achieved drawing
from 787 suppliers experience.

Now they need secure the financing. You've noticed China has gotten a
5% share in the programme, Aeroflot has let its 22 delivery slots on
787 expire, so shouldn't rule out a deal for Russia as well.
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JFMEZEI
2006-11-07 06:03:28 UTC
Permalink
Re: Airbus thinking about A350 V 4.0 with all composite fuselage.

At this point in time, Airbus needs to settle on a design and get on with
it. As it stands, Airbus has no credible products in the widebody market
and delivery dates that keep on skipping.

They are better off announcing all composite fuselage and I'd say even go
as far as bleedless engines to match the 787 and then work to get orders
and get financing later on. At least they'll have a design they can work
on, refine, and define in details so that when financing/orders come in,
they can launch it and they already have a lot of the work done.

A rolling stone gathers no moss. Right now, the 350 has changed so many
times that Airbus is wasting engineering resources who continuously have to
ditch their work to restart on a new version of the 350. And the market
doesn't like this either because there is no trust that the current 350
won't be ditched and switched for yet another version later on.

If Airbus is affraid of a lack of engineering resources, it probably means
that Airbus is still very busy improving the A380 and trying hard to shed
more weight from it. If the aircraft itself was really ready for prime
time, Airbus wouldn't be needing engineering resources for the aircraft
structures since it would simply be waiting for the germans to get their
act together to produce wiring harnesses.

Another aspect is a political one. So far the composite expertise within
Airbus has been in Spain (CASA) and the UK (aircraft wings). So France and
Germany have not developped the tooling/expertise to do major composite
parts. But politicnas would want to see the 350 generate lots of jobs in
France and Germany.

I wouldn't be surprised to see China get a big part of the work for the
350. When they're not making plastic christmas toys, they could re-ue
their machines to spit out plastic fuselage plugs :-) :-)

And if China subsidizes chinese plants that make 350 parts, then Airbus
won't be accused of government subsidies. It will be on equal footing with
Boeing since Boeing relies on a foreign government (Japan) subsidizing
construction of major parts of the 787.
.
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Tom Sanderson
2006-11-07 15:10:58 UTC
Permalink
"JFMEZEI" <***@vaxination.ca> wrote:
> They are better off announcing all composite fuselage and I'd say even go
> as far as bleedless engines to match the 787 and then work to get orders
> and get financing later on. At least they'll have a design they can work
> on, refine, and define in details so that when financing/orders come in,
> they can launch it and they already have a lot of the work done.

The problem there is that they really won't have a compelling sales pitch,
since the airplane will basically be a 787. They'll be able to lean on
their fleet commonality and Airbus flight deck, but other than that it would
be a 787. They wouldn't have a price edge, they wouldn't have a performance
edge, and they wouldn't have a maintenance edge.

Tom.
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Daniel
2006-11-07 17:58:03 UTC
Permalink
> The problem there is that they really won't have a compelling sales pitch,
> since the airplane will basically be a 787. They'll be able to lean on
> their fleet commonality and Airbus flight deck, but other than that it would
> be a 787. They wouldn't have a price edge, they wouldn't have a performance
> edge, and they wouldn't have a maintenance edge.

Perhaps they'd have a political edge, as was explained at length after
Chirac's visit... Maybe that matters on some (key) markets?
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JFMEZEI
2006-11-07 22:18:01 UTC
Permalink
Tom Sanderson wrote:
> The problem there is that they really won't have a compelling sales
> pitch, since the airplane will basically be a 787.

When you compare the 320 and 737, they are essentially identical. But
Airbus has added its touches to it, with slightly wider fuselage, Airbus
flight deck, various design features etc etc.

So while the airframe and engines would be the same, Airbus can still
differentiate itself with little features/designs. And it can also make a
huge difference in the way it sells the aircraft (sales pitch, finacing
arrangement, buy back of older aircraft etc etc).

Also, it isn't enough to design the "same" aircraft. Airbus would have to
be able to build it at lesser cost than Boeing.

I think that the past year has highlighed the fact that perhaps Airbus
never really built good aircraft, its success was just a reflection of
Boeing's lethargy. And now that Boeing is alive again, Airbus is faltering
big time.
.
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Paul G.
2006-11-08 02:17:26 UTC
Permalink
Tom Sanderson wrote:
> The problem there is that they really won't have a compelling sales pitch,
> since the airplane will basically be a 787. They'll be able to lean on
> their fleet commonality and Airbus flight deck, but other than that it would
> be a 787. They wouldn't have a price edge, they wouldn't have a performance
> edge, and they wouldn't have a maintenance edge.
>
> Tom.

Considering that the 787 is a big leap forward, wouldn't an Airbus
version that is as good as the 787 be good enough? It would at least
get them back in the game. If it isn't, what strategy would you suggest
that Airbus pursue?
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Tom Sanderson
2006-11-08 15:15:22 UTC
Permalink
"Paul G." <***@yahoo.ca> wrote:

> Considering that the 787 is a big leap forward, wouldn't an Airbus
> version that is as good as the 787 be good enough? It would at least
> get them back in the game.

That's a darn good point. An A350 that was an even match for the 787 could
probably get 50% of the market, or close to it. I'm not convinced Airbus
can get a full match, but I'm sure they can get close enough if they get the
A380 under control and can devote the engineering resources to it.

> If it isn't, what strategy would you suggest that Airbus pursue?

I'm really not sure...given that I think Boeing has the right strategy for
the market, I guess I have to think that aping Boeing is the right thing to
do. Had I been in Airbus's shoes, purely from a business point of view, I
would have made the A380 a direct 747 competitor, not one-size bigger...that
would have curtailed a lot of the operational risk of the A380, fixed the
airport infrastructure issues, avoided the embarassing "what do we do with
the A340?" question, and allowed Airbus to really offer a compelling
aircraft over the current market entry (747-400). At this point, of course,
it's too late for that.

Rolling out a new single-aisle, or a major derivative, instead of the A350
would have been an interesting ploy as well. Though not "due" yet, it could
have upset the balance of A320/737 sales, which would significantly distract
Boeing. The profit margin on this type of plane is low, but the sales
volume is huge and it provides faster market penetration than anything else,
enabling you to get in with more operators.

I think what Airbus fundamentally messed up was trying to continuosly tweak
a derivative program to match an all-new program. Failure to recognize the
threat of the 787 the first time was one thing, but they made the same
mistake about 3 times over.

Tom.
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JF Mezei
2006-11-08 22:24:32 UTC
Permalink
Tom Sanderson wrote:
> That's a darn good point. An A350 that was an even match for the 787
> could probably get 50% of the market, or close to it.

They could get 50% of the *remaining* market. By the time Airbus has a
credible 350 offering, Boeing will probably have gobbled up 600 to 700 orders.

If the total market is say 2000 aircraft for the next 20 years, once Airbus
enters the market, there would be only 1300 aircraft left to sell, so
Airbus would get 650, while Boeing would get 700+650 = 1350 aircraft.

This is why it is very important for Airbus to get its act together ASAP
because every month of delay before they launch a credible final version of
the 350 are sales that are lost forever. And for every airline that chooses
the 787 since Airbus has no credible product, well that airline is likely
to order more 787s once they need more planes.

Airbus has already lost Air Canada because of the lack of the 787 and
ancient 340s.

>I guess I have to think that aping Boeing is the right
> thing to do. Had I been in Airbus's shoes, purely from a business point
> of view, I would have made the A380 a direct 747 competitor, not
> one-size bigger...

Airbus already had the 340 to compete against the 777. It had nothing
against the 747 and that was a big hole in Airbus' product offering.

Had Airbus sacrificed the 340 fully back in the mid 1990s and scaled the
330 to compete against the 777, the story might be different today.


If the 350 ends up being identical to the 787 in terms of
technologies/performance, it might still give Airbus one big advantage. If
Airbus scales its 350 to include both the 777 and 787, then customers would
get a single aircraft type with Airbus instead of 2 aircraft types for
Boeing. (At least if it can compete against the 777-200__)


I think that Airbus should step back for a second and accept that it
currently only has one viable product, the A320 family.

The 330 is no longer competitive
The 340 is a farce
The 380 appears to be an overweight dud.

It is possible that the 380 might be rescued and given a weight diet
because the 787 is still an "older" product.

But the 330 and 340s are dead in the water because they compete against the
much newer 787.
.
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Paul G.
2006-11-09 02:20:45 UTC
Permalink
Thanks for your comments Tom. I am no aviation expert; but do enjoy
watching the battle between Airbus and Boeing; interesting stuff.

Here's another question I will toss out: should the new A350 attempt to
cover both the 787/777 market or is that a hopeless compromise? And
what can Airbus do with the A340?
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matt weber
2006-11-09 03:15:42 UTC
Permalink
On 8 Nov 2006 21:20:45 -0500, "Paul G." <***@yahoo.ca>
wrote:

>Thanks for your comments Tom. I am no aviation expert; but do enjoy
>watching the battle between Airbus and Boeing; interesting stuff.
>
>Here's another question I will toss out: should the new A350 attempt to
>cover both the 787/777 market or is that a hopeless compromise? And
>what can Airbus do with the A340?
The smartest thing Airbus can do with the A340 is walk away from it.
Emirates has thrown in the towel on the A340, the officially canceled
the A340-600 order a few weeks ago.

From my perspective, the smartest thing Airbus could do today is to
walk away from the A350 as well, and concentrate on a replacement for
the A320/737NG. The time to design a replacement is before the
competition does it for you. The reason the A320 is so succesful is
not because it is such a great airplane, it is that Boeing didn't
produce a sucessor to the 727 on a timely basis. Boeing isn't likely
to have a 737NG replacement available until the 2014 or so time frame.
Boeing engineering is pretty well committed at this point until the
2010 time frame. Once the 787-8 and -9 are close to finalized, the
effort will transfer to the -10. The -10 isn't an if any longer, it is
a when. So if Airbus were to put the resources into a narrow body
replacement, they would have the market to themselves for several
years.

At this point the A350-XWB will enter service so late that unless it
ends up a lot different than the 787 in some ways, it will be largely
irrelevant. Nobody can afford to compete against a 787 with an A340 or
A330. I am reminded of stampede that the 747-400 caused.
NW ordered 10. That in turn forced JAL to order the 747-400 to
compete, which then forced Singapore, China Airlines and Korean to
order 747-400's, which forced Malaysian to order 747-400's...

Very simply when ANA ordered 787's, it forced JAL, Northwest, Qantas
and Air New Zealand to do the same. Singapore airlines suddenly
realized that they didn't have an aircraft with competitive capability
and cost, and that forced Sinapore to order the 787. You can expect a
lot of A350 defections because the airlines who though they were going
to get a 787 competitor in the 2009 time frame, are now looking at
2012....
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Tom Sanderson
2006-11-09 17:21:51 UTC
Permalink
"matt weber" <***@verizon.net> wrote:
> From my perspective, the smartest thing Airbus could do today is to
> walk away from the A350 as well, and concentrate on a replacement for
> the A320/737NG.

I was originally thinking that too, when I was responding to Paul yesterday.
From a technical standpoint, I think you're right, but I don't think they
can make the business case. The profit margin is much tighter in the
single-aisle world and Embraer and Bombadier are pushing that hard.
Single-aisles keep the lights on, but they don't keep your shareholders
happy and they don't give you the free cash to develop new programs.
Granted, Airbus has legitimate political and strategic value beyond just
running a business, so they might be OK with that.

> Boeing engineering is pretty well committed at this point until the
> 2010 time frame. Once the 787-8 and -9 are close to finalized, the
> effort will transfer to the -10. The -10 isn't an if any longer, it is
> a when.

I'm not sure about that. Engineering resources on the 787 should peak next
year and then start to drop off; those engineers will be available for the
new single-aisle. Final design will be complete next year, which frees most
of the design engineers. Some will have to stay on for the -10, but a
derivative is a lot less work than a whole new model. Manufacturing
engineering will be in the thick of it until they hit full production rate
but, again, most of the manpower goes in up front and it's just refinement
from then on.

> So if Airbus were to put the resources into a narrow body
> replacement, they would have the market to themselves for several
> years.

I think Airbus has at least as much tied up in the A380 and A400M, which
they can't walk away from, as Boeing does in the 787. As I read it, most of
those engineers will all be coming available for a new single-aisle at about
the same time from both manufacturers. I'm sure they're watching each other
like hawks because neither one really wants to do a new single-aisle, but as
soon as one does the other has to immediately follow suit to maintain
parity. I think they're playing a game of chicken right now...preliminary
development behind the scenes, but very little public acknowledgement.

Tom.
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Daniel
2006-11-09 18:58:45 UTC
Permalink
> > From my perspective, the smartest thing Airbus could do today is to
> > walk away from the A350 as well, and concentrate on a replacement for
> > the A320/737NG.
>
> I was originally thinking that too, when I was responding to Paul yesterday.
> From a technical standpoint,

There's evidence that's what they wanted to do, have their first
all-new plane in the SA segment. But this plan had to be ditched as
they found out they couldn't get away with an improved A330 to compete
against 787. They totally failed in their reading of 787 as they
acknowledged, and not just once. They cannot afford to let Boeing rule
alone in the critical TA segment as Tim Clark outlined. They'll be
playing catch up now for the next 15 years as Streiff has put it.
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Tom Sanderson
2006-11-09 17:14:23 UTC
Permalink
"Paul G." <***@yahoo.ca> wrote:
> Here's another question I will toss out: should the new A350 attempt to
> cover both the 787/777 market or is that a hopeless compromise? And
> what can Airbus do with the A340?

I think it's possible, but it's a significant challenge. I know I've heard
several Boeing engineers who know this kind of stuff inside and out be very
skeptical that one aircraft can efficiently span that large a range.
However, if they can pull it off, it will be a major technical (and probably
sales) victory for Airbus.

It really depends on how much they're willing to allow the different
versions to become structurally different. A fuselage optimized for one
size is going to be too heavy for a shrink and too weak for a stretch (same
for the wing). If they're willing to give up some structural commonality to
optimize to more than one size (but keep all their systems the same) it can
be done.

The A340 is pretty much doomed. The only thing that might save it is if PW
develops a good geared turbofan for the new single-aisles; that could
re-engine the A340 and get it back to where it was originally supposed to
be. During development, the A340 was supposed to have the IAE Superfan
engine and it wasn't until pretty late in the game that IAE pulled out and
they had to go to the CFM56. Part of the fuel burn problem on the A340 is
that it never got the engine it was designed to have.

The other thing that may turn out to be a big strategic win for Airbus is
their investment in AlLi alloy technolgy and advanced joining (friction-stir
welding, etc.). All the evidence I've seen says composite is the way to go,
but Boeing is in somewhat uncharted territory here and it's always possible
there will be some big hiccups. If customer sentiment swings against
composites, Airbus will be in a very good position to capitalize on that (if
they don't crack and make the A350 all composite too).

Tom.
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Daniel
2006-11-09 19:02:59 UTC
Permalink
> The A340 is pretty much doomed. The only thing that might save it is if PW
> develops a good geared turbofan for the new single-aisles; that could
> re-engine the A340 and get it back to where it was originally supposed to
> be. During development, the A340 was supposed to have the IAE Superfan
> engine and it wasn't until pretty late in the game that IAE pulled out and
> they had to go to the CFM56. Part of the fuel burn problem on the A340 is
> that it never got the engine it was designed to have.

I thought Airbus had that idea of producing a quad with short haul
engines commonality back in the 70s - project designation TA11. CFM56
was around then, not sure IAE's V2500. Anyways, those engines are
optimized for short haul. Can retaining those engine's cores ever
produce anything good for sustained high altitude cruise?
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Tom Sanderson
2006-11-10 14:29:41 UTC
Permalink
"Daniel" <***@hotmail.com> wrote:
>> The A340 is pretty much doomed. The only thing that might save it is if
>> PW
>> develops a good geared turbofan for the new single-aisles; that could
>> re-engine the A340 and get it back to where it was originally supposed to
>> be. During development, the A340 was supposed to have the IAE Superfan
>> engine and it wasn't until pretty late in the game that IAE pulled out
>> and
>> they had to go to the CFM56. Part of the fuel burn problem on the A340
>> is
>> that it never got the engine it was designed to have.
>
> I thought Airbus had that idea of producing a quad with short haul
> engines commonality back in the 70s - project designation TA11. CFM56
> was around then, not sure IAE's V2500.

I think you're right, but the IAE V2500 isn't the same thing as the IAE
Superfan. The former is a direct competitor to the CFM56, the latter was a
V2500 core driving a geared, variable-pitch fan. Sort of like the UDF in
the US, only with a shroud. It would have had much higher bypass and,
supposedly, about 20% better fuel burn for its time.

The whole A340 airframe was never designed to have an engine as thirsty as
the CFM56.

> Anyways, those engines are optimized for short haul.

A CFM56 is good for something like 15-hours at 40,000'+, at least. How long
haul do you want to be?

> Can retaining those engine's cores ever produce anything good for
> sustained high altitude cruise?

Sure. It's the fan, not the core, that really drives your performance.

Tom.
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Daniel
2006-11-10 15:57:48 UTC
Permalink
> A CFM56 is good for something like 15-hours at 40,000'+, at least. How long
> haul do you want to be?

Was thinking fuel-wise.

> > Can retaining those engine's cores ever produce anything good for
> > sustained high altitude cruise?
>
> Sure. It's the fan, not the core, that really drives your performance.

Is CFM56 thirsty because of its core, or fans not being being adequate?
Initially it was launched to re-engine KC135s and power new generation
short haul aircraft. That would seem to be conflicting needs, so has it
suffered from some sort of compromise from the outstart? What was to
prevent SNECMA to come up with a set of proper fans for A340s if that's
the solution? Are there IP arrangements with GE within the CFM venture
that restrict derivatives?
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Daniel
2006-11-10 17:08:31 UTC
Permalink
Discard questions. Think I just properly compiled your answer. A340
would have been a good aircraft with totally unrealistic UDF engines.
Then 4 is never a good option when you can do 2, whatever the
core/fans. Yes makes sense, and you are being diplomatic :)
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Tom Sanderson
2006-11-10 20:30:04 UTC
Permalink
"Daniel" <***@hotmail.com> wrote:
> A340 would have been a good aircraft with totally unrealistic UDF engines.

Bingo. Airbus did their whole design thinking they'd have an engine with
some very low specific fuel consumption, then got hit where it hurts most
when IAE said they couldn't build the engine. Airbus rallied nicely with
what they could, got CFM to do the -5 derivative, and charged forward.
Unfortunatley, development of the really big engines for the 777 pretty much
kicked the idea of 4 small engines to the curb, as you noted.

Tom.
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Daniel
2006-11-10 22:19:12 UTC
Permalink
> Bingo.

And Banco when they made matters worse putting 4 big engines on
-500/600. At least 200/300 was a challenger for MD11, although didn't
even match that one's payload...
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matt weber
2006-11-12 21:36:42 UTC
Permalink
On 10 Nov 2006 09:29:41 -0500, "Tom Sanderson" <***@yahoo.com>
wrote:

>"Daniel" <***@hotmail.com> wrote:
>>> The A340 is pretty much doomed. The only thing that might save it is if
>>> PW
>>> develops a good geared turbofan for the new single-aisles; that could
>>> re-engine the A340 and get it back to where it was originally supposed to
>>> be. During development, the A340 was supposed to have the IAE Superfan
>>> engine and it wasn't until pretty late in the game that IAE pulled out
>>> and
>>> they had to go to the CFM56. Part of the fuel burn problem on the A340
>>> is
>>> that it never got the engine it was designed to have.
>>
>> I thought Airbus had that idea of producing a quad with short haul
>> engines commonality back in the 70s - project designation TA11. CFM56
>> was around then, not sure IAE's V2500.
>
>I think you're right, but the IAE V2500 isn't the same thing as the IAE
>Superfan. The former is a direct competitor to the CFM56, the latter was a
>V2500 core driving a geared, variable-pitch fan. Sort of like the UDF in
>the US, only with a shroud. It would have had much higher bypass and,
>supposedly, about 20% better fuel burn for its time.
>
>The whole A340 airframe was never designed to have an engine as thirsty as
>the CFM56.
>
>> Anyways, those engines are optimized for short haul.
>
>A CFM56 is good for something like 15-hours at 40,000'+, at least. How long
>haul do you want to be?
The problem was the CFM56-5C involved a stretch far beyond what CFM
had intended for the engine family, and while the SFC is actually very
good given the circumstances, there isn't much doubt that the Superfan
would have been much better. The Bind the Superfan ran into is a
little analogous to what bankrupted RR. Nobody doubts it can be done,
but only the Russians have experience building 10,000 hp gear boxes
for aviation use. The IAE board of directors looked at the risks, and
the RR composite fan blade fiasco was still well within memory. The
RB211 was supposed to be built with a composite fan, the problems in
building it bankrupted RR. It took another 25 years to successfully
build a jet engine with composite blades on the fan. So far the only
engine with a composite fan blades is the GE90, which is a composite
fan on a titanium spar.

In any case, IAE decided the risks weren't worth the benefits, and
decided to cancel the program. Airbus thought they had a 'hard' deal
with IAE, and were more than a little unhappy with IAE over being
dumped. SNECMA came under immense pressure to convince GE to build a
larger CFM for the A340.

There is gear driven fan available now, but even it had it problems.
The A318 was supposed to use the geared fan PW6000 exclusively. The
engine failed to meet performance goals, and every A318 delivered so
far has had CFM56's. The PW6000 fortunately doesn't need a 10,000 hp
gear box.

Interestingly enough, CFM was offered an exclusive on the
A340-500/600, and took a walk. They didn't think enough airframes
would be sold to recover the 10 figure cost of an all new engine. It
appears they were right.
>
>> Can retaining those engine's cores ever produce anything good for
>> sustained high altitude cruise?
The core had to be reworked extensively. An extra compressor stage
was added to later to the 7B and 7C CFM56's (The 7C is the A340
engine), and the 7C has an extra low pressure turbine stage, and the
7C fan is larger than the 7B and 7A fan).
>
>Sure. It's the fan, not the core, that really drives your performance.
>
>Tom.
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Tom Sanderson
2006-11-14 04:24:53 UTC
Permalink
"matt weber" <***@verizon.net> wrote:
> The Bind the Superfan ran into is a
> little analogous to what bankrupted RR. Nobody doubts it can be done,
> but only the Russians have experience building 10,000 hp gear boxes
> for aviation use.

Supposedly P&W is getting that under control now. And I assume they've got
something close to that for the STOVL version of the JSF. So IAE was only
about 30 years too far ahead of their time.

> So far the only
> engine with a composite fan blades is the GE90, which is a composite
> fan on a titanium spar.

Is it titanium spar, or titanium leading edge? I thought it was all carbon,
structurally, with Ti on the leading edge for impact resistance. Whatevey
they did, those things are tough.

Tom.
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Paul G.
2006-11-16 04:01:23 UTC
Permalink
In the Seattle Times today, during an interview with John Leahy of
Airbus, he stated Airbus's approach to composites on the A350 Version
?:

============
""The one thing we're not looking at, at all, is Boeing's concept of
doing this male mold where you wrap the fabric around it and have this
one piece coming off the line. Our engineering staff are pretty
convinced that is not at all the way to go.

"The customers don't seem to care that much, as long as the airplane
has the performance, the economics and the reparability. And that's
where composites gets people worried a bit, on the reparability. They
ask, how are we going to repair it?

"Anything you see with Airbus will have composites perhaps in sections
that can be removed and repaired rather easily. Whereas what Boeing is
doing is this one big male mold which produces one-piece fuselages.

"Most of the world's airlines, at least the ones I've been talking to,
have big concerns about that."

http://seattletimes.nwsource.com/html/businesstechnology/2003431623_leahyweb15.html
============

Can anyone comment on the viability/desirability of Airbus's approach
to a composite fuselage as compared to Boeing's with the 787?
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JF Mezei
2006-11-16 05:50:36 UTC
Permalink
Paul G. wrote:
> In the Seattle Times today, during an interview with John Leahy of
> Airbus, he stated Airbus's approach to composites on the A350 Version

Thanks for the link. Interesting article.


> has the performance, the economics and the reparability. And that's
> where composites gets people worried a bit, on the reparability. They
> ask, how are we going to repair it?

Sounds to me like Airbus' arguments against ETOPS in order to justify its 4
engined 340s.

In the one hand, Leahy admits that Airbus had underestimated Boeing's
technical capabilities, and on the other, it says that the one piece
fuselage plugs are no good.

For "ramp rash", I suspect that fix kits should be as simple as fixing
similar problems with fiberglass boats. But I suspect that because you need
to wait for the resin to cure (24 to 48 hours with typical resins), the
aircraft may remain out of service for longer.

Where there may be a real difference in in cases similar to Northwest
rebuilding its DC-9s. On the 787, you cannot change the skin because it is
an integral part of the fuselage structure.

How common are aircraft maintenance programmes that see whole pieces of
fuselage skin replaced ? If composite fuselage can truly outlast the
aircraft due to lack of corrosion, then maintenance programmes that include
replacing skin sections may no longer be necessary, so the fact that you
can't replace fuselage skin may no longer be a factor.

Think back to the Aloha convertible 737 where long life/many cycles
resulted in rivets weakening and parts of the skin popping off under
pressure. If carbon fibre fuselages make such occurances impossible
throughout the full diraction of aircraft (and beyond), then the
non-replacability of fuselage skin panels is not an issue.

With Airbus' plans to use friction fit welding, replacing fuselage skin
panels won't be so simple anyways since you would essentially have a single
sheet of aluminium rolled around the structural ribs. (As opposed to
separate sheets rivetted together.


On the other hand, because, if I remember correctly, Boeing will still use
rivets to bond window frames to the fuselage and to bond fuselage plugs
together, there may be long term issues with rivets, but I suspect that
they could pop the rivets off, apply some resin in the rivet holes and
insert new rivets which will again fit snugly.

In the end, Boeing has 400 orders. Airbus hasn't even left the starting
gate yet. And that is what really counts.

Two items of interest in that article:

Leahy's heart problems. Leahy has been key to catching major sales at
Airbus. If he is forced to scale down his involvement, this could be bad
news for Airbus.

Another item is Leahy admitting that Airbus had underestimated Boeing's
technological capabilities for the 787. Is this just another PR excuse, or
is it really true ? If it is really true,
.
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Tom Sanderson
2006-11-16 15:12:32 UTC
Permalink
"JF Mezei" <***@vaxination.ca> wrote:
> For "ramp rash", I suspect that fix kits should be as simple as fixing
> similar problems with fiberglass boats. But I suspect that because you
> need to wait for the resin to cure (24 to 48 hours with typical resins),
> the aircraft may remain out of service for longer.

As far as I'm aware, neither manufacturer uses catalytic
(fiberglass-boat-type) resins for structural parts. They use themosetting
resins...you bake 'em to set 'em. It only takes an hour or two under a heat
blanket and you're done. I pick up "off-spec" prepreg carbon fiber from the
Boeing Surplus Store when they have it and it sets up just fine by baking in
the toaster oven at 250F for an hour.

> Where there may be a real difference in in cases similar to Northwest
> rebuilding its DC-9s. On the 787, you cannot change the skin because it is
> an integral part of the fuselage structure.

Boeing's hope, I think, is that you'll never have to change the skin. It's
basically immune to corrosion and fatigue, so unless you take massive damage
from something, you shouldn't need to replace it.

> How common are aircraft maintenance programmes that see whole pieces of
> fuselage skin replaced ?

Rare. I've only ever seen it done for really old airplanes or really
damaged airplanes. I've never heard of any operator doing it just to repair
local damage...a repair doubler is far easier to do.

> then maintenance programmes that include replacing skin sections may no
> longer be necessary,

So far as I know, replacing fuselage panels is not part of any scheduled
maintenance program...the structure is supposed to last the life of the
aircraft. If someone is replacing it it's due to exceeding design life or
significant damage.

> Think back to the Aloha convertible 737 where long life/many cycles
> resulted in rivets weakening and parts of the skin popping off under
> pressure. If carbon fibre fuselages make such occurances impossible
> throughout the full diraction of aircraft (and beyond), then the
> non-replacability of fuselage skin panels is not an issue.

Aloha was a combination of a bunch of things that make it more complex than
just a material selection problem. The single biggest thing that went wrong
there is that that failure mode just wasn't something that anyone looked
for. In hindsight, it was obvious (like most things), but prior to Aloha
most manufacturers looked at fatigue in isolation. Aloha is what happens if
a whole bunch of non-critical fatigue cracks occur in close proximity to
each other.

Beyond that, you had an aircraft with a very unusual flight profile in a
very corrosive environment with a less than stellar maintenance program.
The fact that the thing landed at all is more a testament to good design
than bad.

> On the other hand, because, if I remember correctly, Boeing will still use
> rivets to bond window frames to the fuselage and to bond fuselage plugs
> together, there may be long term issues with rivets, but I suspect that
> they could pop the rivets off, apply some resin in the rivet holes and
> insert new rivets which will again fit snugly.

The usual method is to just drill the existing holes one size larger and use
a bigger rivet. Rivets by themselves aren't usually the problem, it's the
surrounding material. That's an issue for any bolt-type fastener (the skin
can't really tell a rivet from a Hi-Lok). A lot of the 787 will use
adhesive as the primary load path with rivets for the backup, as I recall.

Tom.
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JF Mezei
2006-11-17 03:04:58 UTC
Permalink
Tom Sanderson wrote:
> As far as I'm aware, neither manufacturer uses catalytic
> (fiberglass-boat-type) resins for structural parts.

I was thinking that baking the whole aircraft to cure a path was not quite
realistic :-), hence my assumption that patches would e made with catalytic
resins. I wasn't aware that some heat blanket would be sufficient to get
the job done and get it to cure in even less time.

I assume however that they will use carbon fabric to make patches ?

With current aluminium planes, when they need to apply a patch of
aluminium, do they need access to both sides of the skin or can they work
solely from the outside to apply the patch ?

With a fabric/resin fix, wouldn't they need access to the skin from the
inside to ensure that the patch is bigger than the hole on the pressurised
side ? with a patch on the inside providing the pressure vessel strenght,
and the patch on the ouside side just being a filler and cosmestic surface ?

> Boeing's hope, I think, is that you'll never have to change the skin.
> It's basically immune to corrosion and fatigue, so unless you take
> massive damage from something, you shouldn't need to replace it.


I think this is where Airbus may strike a chord with customers. What if
some new unanticipated problem props up over the years which requires
changing skin panels ?

Some may say that there is enough experience already with composites to
know about any/all possible problems. And I suspect Airbus will focus on
uncertainties while Boeing will focus on the sufficient amount of
experience to know carbon fibre is reliable.

At least in the twin*4 engine debate, Airbus had a valid argument that
twins were prevented from using shortest route on some city pairs. But with
the composites, I am not sure that there are REALLY any situations where
panels would be better.

> aircraft. If someone is replacing it it's due to exceeding design life
> or significant damage.

In the case of Boeing and Airbus, it is not to their advantage to see
airlines do like Northwest and extend the life of their DC9s instead of
buying new planes.

And to prevent this, both manufacturers need to produce new aircraft whose
improved fuel efficiency/TCO is lower enough to justify ditching the older
aricraft and buying new.

I think one big issue will be the environment. Since aircraft have a
lifetime of roughly 15-20 years, one needs to consider that within this
timeframe, there may be major pollution taxes and fuel cost increases or
even totally new less polluting fuel (Jet-Bio ?) which may foster a fleet
replacement cycle.

If this requires aircraft changes, then longevity of the 787 fuselage may
not be in issue. If this requires just engine changes, then airlines may
want an aircraft that still has enough life left to justify the purchase of
new engines for it.

This is not really an issue now. But it may be by the time the 737/320s are
up for renewall.

> Aloha was a combination of a bunch of things that make it more complex
> than just a material selection problem.

Look at how long it took to discover those flaws. What if Boeing's
manufacturing process doesn't prevent flaws that are currently unknown but
which may surface in 20 years time ? I bet Airbus will use those scare
tactics on customers.

.
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Tom Sanderson
2006-11-17 15:33:25 UTC
Permalink
"JF Mezei" <***@vaxination.ca> wrote:
> I assume however that they will use carbon fabric to make patches ?

Not sure. Probably, since I can't really see any reason not too. It's
readily available and just as easy to handle as fiberglass but much
stronger. Kevlar is a bitch to work with, so I doubt they'd use that for
repair unless they had to.

All that said, I think Boeing said they could use "conventional repair
techniques" (read: aluminum patches) if they wanted to.

> With current aluminium planes, when they need to apply a patch of
> aluminium, do they need access to both sides of the skin or can they work
> solely from the outside to apply the patch ?

Depends on the repair, but it should usually be doable just from the
outside. To do that, you need to use blind fasteners, but those are easy to
come by. In most parts of the plane, getting access to the inside of the
skin isn't that difficult though...pull off the sidewall and the insulation
blanket and you're there...have to work around the wire bundles, but that's
usually not too bad.

> With a fabric/resin fix, wouldn't they need access to the skin from the
> inside to ensure that the patch is bigger than the hole on the pressurised
> side ?

Nope. Almost all the load in the fuselage skin is hoop stress (from
pressurization) and shear (from flight loads). The direct pressure load on
the patch is relatively small for normal-sized damage.

> I think this is where Airbus may strike a chord with customers. What if
> some new unanticipated problem props up over the years which requires
> changing skin panels ?

That's certainly a risk, possibly a fatal one. However, Airbus has to be
careful about pushing it for two reasons. 1) They greatly expanded the use
of friction-stir welding, AlLi alloy, and GLARE on the A380...almost all the
risk issues on new material that Airbus can lob at Boeing can be lobbed
right back at Airbus. 2) Airbus and Boeing both use composites all over the
place, including critical flight controls. If Airbus begins suggesting that
composite panels can't be trusted, it's going to really throw some doubt on
their ability to get other composite parts right, which hurts both
manufacturers.

> At least in the twin*4 engine debate, Airbus had a valid argument that
> twins were prevented from using shortest route on some city pairs.

That used to be a valid argument, although I'm not sure that the improved
fuel burn of the twins didn't make up for the extra distance. I think now,
with 208-minute ETOPS, it's probably a moot point.

> In the case of Boeing and Airbus, it is not to their advantage to see
> airlines do like Northwest and extend the life of their DC9s instead of
> buying new planes.

Designing huge structural repairs like that is also an enourmous amount of
work. I'm assume Northwest had to pay to develop the repair since that's
way outside the bounds of normal customer support, but it's still
engineering work that I'm sure Boeing would rather spend on something else.

> I think one big issue will be the environment. Since aircraft have a
> lifetime of roughly 15-20 years,

That's certainly the planned lifetime...so far, the actual lifetime is
averaging something around 35 years. This is just now starting to bite
Airbus, but both manufacturers haven't got a really sound plan to deal with
the fact that operators are running these airframes way past the point they
were designed for.

>> Aloha was a combination of a bunch of things that make it more complex
>> than just a material selection problem.
>
> Look at how long it took to discover those flaws. What if Boeing's
> manufacturing process doesn't prevent flaws that are currently unknown but
> which may surface in 20 years time ? I bet Airbus will use those scare
> tactics on customers.

Absolutely a risk but, like the argument above, Airbus needs to be careful
about how the pitch that. It could backfire and hit both companies.

Tom.
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John L
2006-11-17 16:32:08 UTC
Permalink
>> At least in the twin*4 engine debate, Airbus had a valid argument that
>> twins were prevented from using shortest route on some city pairs.
>
>That used to be a valid argument, although I'm not sure that the improved
>fuel burn of the twins didn't make up for the extra distance. I think now,
>with 208-minute ETOPS, it's probably a moot point.

There's still some southern routes where it matters. You can't do
SYD-GIG with ETOPS 240, or EZE-PER even with ETOPS 330.

But I agree that since the 747 and 380 are not going away, the small
number of routes that twins can't fly is no longer a big deal.

R's,
John
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jbaloun
2006-11-17 17:48:27 UTC
Permalink
Tom Sanderson wrote:
> > Look at how long it took to discover those flaws. What if Boeing's
> > manufacturing process doesn't prevent flaws that are currently unknown but
> > which may surface in 20 years time ? I bet Airbus will use those scare
> > tactics on customers.
>
> Absolutely a risk but, like the argument above, Airbus needs to be careful
> about how the pitch that. It could backfire and hit both companies.
>
> Tom.
> --

This hints at one of the rarely discussed details of air transport
manufacturing. The passengers are the Guinea pigs. There will always be
some risk to flying.

After careful design and analysis, due dilligence on the part of the
manufacturers, the regulatory agencies, and the operators, along with
a carefully executed, industry standard maintenance plan of A, B, C,
and D checks, still some of the problems can only be found in
operation. So there is a slight and risk remaining for the passengers
as the fleet operates which grows as the fleet ages. The result is,
engines shed blades, doors blow open, panels rip off, spar caps and
heavy fittings crack, landing gear stay up or stay down, and hundreds
of other little annoying problems that keep the ground crews and
maintenance techs busy.

ADs and other shared data alert the inspectors on where to look for the
potential failures. This information is shared world-wide. I have
worked with inspectors who were well aware of where to look to spot
problems while keeping an eye on the rest of the plane.

These are amazingly complex machines that are in general very well
designed and maintained. If only our cars were designed as well they
would also last for 20 years on a regular basis. But then they would
cost US$100,000. Still when we are waiting at the gate and the plane
pulls up, unloads, and loads and leaves, I hope the ground crew was
able to find and prevent any possible failures about to happen.

Some airlines have almost no engineers on staff. I hope they have
enough maintenance crews. Some airlines tend to run the planes until
they break. Boeing, Airbus and the other manufacturers have their hands
full making their planes as reliabale as they can while keeping the
cost down.

James
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matt weber
2006-11-16 22:54:12 UTC
Permalink
On 16 Nov 2006 00:50:36 -0500, JF Mezei
<***@vaxination.ca> wrote:

>Paul G. wrote:
>> In the Seattle Times today, during an interview with John Leahy of
>> Airbus, he stated Airbus's approach to composites on the A350 Version
>
>Thanks for the link. Interesting article.
>
>
>> has the performance, the economics and the reparability. And that's
>> where composites gets people worried a bit, on the reparability. They
>> ask, how are we going to repair it?
>
>Sounds to me like Airbus' arguments against ETOPS in order to justify its 4
>engined 340s.
>
>In the one hand, Leahy admits that Airbus had underestimated Boeing's
>technical capabilities, and on the other, it says that the one piece
>fuselage plugs are no good.
>
>For "ramp rash", I suspect that fix kits should be as simple as fixing
>similar problems with fiberglass boats. But I suspect that because you need
>to wait for the resin to cure (24 to 48 hours with typical resins), the
>aircraft may remain out of service for longer.
>
>Where there may be a real difference in in cases similar to Northwest
>rebuilding its DC-9s. On the 787, you cannot change the skin because it is
>an integral part of the fuselage structure.
>
>How common are aircraft maintenance programmes that see whole pieces of
>fuselage skin replaced ? If composite fuselage can truly outlast the
>aircraft due to lack of corrosion, then maintenance programmes that include
>replacing skin sections may no longer be necessary, so the fact that you
>can't replace fuselage skin may no longer be a factor.
>
>Think back to the Aloha convertible 737 where long life/many cycles
>resulted in rivets weakening and parts of the skin popping off under
>pressure. If carbon fibre fuselages make such occurances impossible
>throughout the full diraction of aircraft (and beyond), then the
>non-replacability of fuselage skin panels is not an issue.
>
>With Airbus' plans to use friction fit welding, replacing fuselage skin
>panels won't be so simple anyways since you would essentially have a single
>sheet of aluminium rolled around the structural ribs. (As opposed to
>separate sheets rivetted together.
>
>
>On the other hand, because, if I remember correctly, Boeing will still use
>rivets to bond window frames to the fuselage and to bond fuselage plugs
>together, there may be long term issues with rivets, but I suspect that
>they could pop the rivets off, apply some resin in the rivet holes and
>insert new rivets which will again fit snugly.
>
>In the end, Boeing has 400 orders. Airbus hasn't even left the starting
>gate yet. And that is what really counts.
>
>Two items of interest in that article:
>
>Leahy's heart problems. Leahy has been key to catching major sales at
>Airbus. If he is forced to scale down his involvement, this could be bad
>news for Airbus.
>
>Another item is Leahy admitting that Airbus had underestimated Boeing's
>technological capabilities for the 787. Is this just another PR excuse, or
>is it really true ? If it is really true,
>.
The reality is damage to the fuselage is relatively uncommon. Most of
the FOD is to leading edges, engine nacelles, flaps (which are
deployed on takeoff/landing), gear doors etc. In addition thrust
reversers tend to take a beating. Many of the these parts transitioned
to composites in the 1980's, and have now gone back to Aluminum
because these parts DO get banged up, and it is a lot easier to fix
them if they are Aluminium instead of composite.
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Tom Sanderson
2006-11-17 15:19:12 UTC
Permalink
"matt weber" <***@verizon.net> wrote:
> The reality is damage to the fuselage is relatively uncommon. Most of
> the FOD is to leading edges, engine nacelles, flaps (which are
> deployed on takeoff/landing), gear doors etc. In addition thrust
> reversers tend to take a beating. Many of the these parts transitioned
> to composites in the 1980's, and have now gone back to Aluminum
> because these parts DO get banged up, and it is a lot easier to fix
> them if they are Aluminium instead of composite.

I know that Southwest made a major flap about composite engine nacelles on
the 737NG, but I think some of the parts you name that went composite are
still composite.

Leading edges are metal because of the anti-ice system...composites would
get cooked. Nacelle leading edges and cowl are still aluminum, definitely,
for the reasons you cite.

Flaps and TR's, so far as I know, are all still composite.

Tom.
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jbaloun
2006-11-16 05:52:05 UTC
Permalink
Paul G. wrote:
> In the Seattle Times today, during an interview with John Leahy of
> Airbus, he stated Airbus's approach to composites on the A350 Version
> ?:

> Our engineering staff are pretty convinced that is not at all the way to go.
> They ask, how are we going to repair it?
> "Anything you see with Airbus will have composites perhaps in sections
> that can be removed and repaired rather easily.

It sounds like Airbus is going around bad-mouthing Boeing's one-piece
composite fuselage design. We may be hearing more about repairability
from Airbus as the A350 gets going. This approach may backfire if
Boeing clearly demonstrates that they have an easy, low cost and
reliable method of repairing the 787 fuselage because if they don't
Boeing will surely throw R/D money at the problem until the do.

Leahy is a little vague here referring to "anything you see with
Airbus". Taking his comments in context with his statements about
Boeings method of using a one-piece fuselage tool it sounds like he is
talking about the fuselage and not "anything" which may include the
wings, tail, and fairings. As Airbus already makes composite tails and
fairings, and already proposed a composite A350xyz wing, they must
already have a plan for repairing such structures which are likely
similar to Boeing's such structures.

Leahy referred to making a composite fuselage of panels and strongly
implies that they will be more repairable than Boeing's one-piece
fuselage. I hope he is speaking for the Airbus engineers and not making
exaggerated promises which may not come true. The fall-back seems to be
that composite technology is not so different in Seattele or Toulouse
and that if a good method of repair exists, it will be available to
both. I just don't see how Airbus will have a significant advantage in
the area of repairability, but then he is not providing us enough
details to make a comparison and neither plane has been build yet much
less operated and damaged.

These separate panels remind me that the A380 Glare panels are
composite/metal. I suspect that Airbus may be proposing composite
panels for the A350 because they are similar to the process for making
the Glare panels and they may be thinking of utilizing existing panel
tooling and or methods. Airbus engineers may have ruled out a one-piece
design not because it is the wrong way to build a fuselage but that
Airbus has already invested in tooling and processes for laying up
panels.

It is possible that Airbus does in fact have a cost-effective way of
laying up panels. Maybe even to the point that it will not cost much to
simply replace a damaged panel rather than repair it. Just keep a panel
layup machine warmed up and when a call comes in for a replacement,
cook one up and ship it out AOG.

Keep in mind that primary fuselage structure has to carry the
pressurization and flight loads and that separate panels, while they
may be made so that they are easier to repair / replace, have to be
spliced together either mechanically for by bonding and to be
marketable have to have minimum weight penalty for the splice.

It can be simpler and cost less to have fewer parts and assemblies like
a 787 fuselage barrel or nose section. A one-piece fuselage is a lot
fewer parts than a "black aluminum" panel fuselage assembly.

We may need to hear more from Airbus and Boeing to make a complete
comparison.

James
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JF Mezei
2006-11-16 06:42:49 UTC
Permalink
jbaloun wrote:
> It sounds like Airbus is going around bad-mouthing Boeing's one-piece
> composite fuselage design.

Just as Airbus was boudmouthing the 777's reliance on only 2 engines which
was extremely dangerous for long haul flights and which may cause deaths of
passengers if the 777 were forced to land in the middle of the winter in
Siberia :-)


> wings, tail, and fairings. As Airbus already makes composite tails and
> fairings, and already proposed a composite A350xyz wing, they must
> already have a plan for repairing such structures which are likely
> similar to Boeing's such structures.

The way I read it, Airbus uses composite *parts* bolted together. Boeing
makes a one piece fuselage plug. Changing a broken skin panel on an Airbus
would be easier than changing a whole fuselage plug of a fully assembled
aircraft with all the wiring passing through it.

If the fuselage skin does not corrode (or otherwise degrade, delaminate
etc), and the skin is an integral part of the fuselage structure (as
opposed to some aluminium sheets rivetted onto the structure) then perhaps
the need to ever replace fuselaqge panels does not exist.

If Airbus goes with separate panels, there may be extra weight since each
panel must overlap the other by a few mm, as well as weight of rivets or
whethever fastener they use.

On the other hand, by having separate panels, Airbus may be able to use
carbon fabric instead of laying tape since for smaller parts, it is much
easier to use fabric to conform to the desired shape. **IF** this allows
for lighter panels due to smaller number of layers, then Airbus *might*
have an advantage.

But somehow, I suspect that Boeing's one-piece design will end up better
since it would bond the skin to the ribs in a more effective way than
rivets or whatever Airbus plans to use.


With more and more airlines willing to outsource aircraft maintenance, it
becomes easier for a few maintenance shops to buy fancy equipment to do
major maintenance/rebuilds of fuselage parts. And as you siad, Boeing will
find a way to deal with this issue if it really needs to be dealt with.

While corrosion may not be an issue, small holes in fuselage that capture
water which goes through freezing/thawing cycles might be an issue.




>I hope he is speaking for the Airbus engineers and not making
> exaggerated promises which may not come true.

I think that there is some truth in what he says. The big question is
whether it is relevant or not. And it also depends on how big those Airbus
pieces are.
> Airbus engineers may have ruled out a one-piece
> design not because it is the wrong way to build a fuselage but that
> Airbus has already invested in tooling and processes for laying up
> panels.

That argument was perhaps valid with 350 V1.0 which was just a 330 built
with existing 330 tooling.

Airbus was told in no equivocal language that this wasn't good enough. They
lost Air Canadad for good because of that mistake.

Now, with the V3.0, the fuselage has no need for any compatibility since it
doesn't have the same cross section.

However, if you go with the Boeing "one piece" fuselage, basically any
contractor can do the job because nobody is equipped to do it. If you
choose panels, it is possible that existing contractors (CASA in spain for
instance) would be able to do the job. So the selection of technology may
be linked to the need to give a certain percentage of contracts to certain
countries. And it is also easier for multiple contractors to participate.


> It can be simpler and cost less to have fewer parts and assemblies like
> a 787 fuselage barrel or nose section. A one-piece fuselage is a lot
> fewer parts than a "black aluminum" panel fuselage assembly.

Harder to distribute the work though, unless you are willing, like Boeing,
to fund the purchase of the expensive layup robots/curing ovens for a
number of distributors.

But in the end, what really counts is the end product. If Airbus is forced
to compromise and use less efficient smaller parts due to internal
political reasons, then its sales will be negatively impacted and Airbus
cannot afford to now have A350 V4.0 that is still a compromise.

HOWEVER, there is the potential for some neat stuff though. Consider that
by building smaller pieces, Airbus *might* be able to make window frames
integral to the fuselage skin and this might give it some weight advantage
compared to Boeing's separate window frames which are riveted to the skin.


It is a real shame though that Leahy would have pretty much confirmed that
Airbus isn't going to go for all-in-1 fuselage plugs. This greatly reduces
the chances that Airbus may end up with a competitive product with the 787,
althopugh it is likely that the stretched version will compete quite well
against the older 777.
.
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jbaloun
2006-11-16 07:06:53 UTC
Permalink
JF Mezei wrote:
> jbaloun wrote:
> > Airbus engineers may have ruled out a one-piece
> > design not because it is the wrong way to build a fuselage but that
> > Airbus has already invested in tooling and processes for laying up
> > panels.
>
> That argument was perhaps valid with 350 V1.0 which was just a 330 built
> with existing 330 tooling.
>
> Airbus was told in no equivocal language that this wasn't good enough. They
> lost Air Canadad for good because of that mistake.
>
> Now, with the V3.0, the fuselage has no need for any compatibility since it
> doesn't have the same cross section.

I was thinking that the new A350 panels would use the existing tooling
but use new composite materials. They may be thinking of making
composte A350 fuselage panels using the Glare tooling (my guess). This
way they do not have to invest in and develop (not so easy) the large
tape lay-up tooling for large fuselage plugs.

My first reaction to Leahy's comments is that Airbus may be able to
pull this off. That is they may end up in the ball-park; i.e. close
enough to a 787 to compete for sales on their own merits.

James
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jbaloun
2006-11-16 07:34:48 UTC
Permalink
jbaloun wrote:

> I was thinking that the new A350 panels would use the existing tooling
> but use new composite materials. They may be thinking of making
> composte A350 fuselage panels using the Glare tooling (my guess). This
> way they do not have to invest in and develop (not so easy) the large
> tape lay-up tooling for large fuselage plugs.
>

To clarify: I am including an assumption the the Glare panel type
tooling is adaptable to different shapes, contours, and diameters and
either the actual tooling or the manufacturing process can be adapted
for the A350 as well as the A380 and any other airframe. If so, the
existing tooling / process is not limited to a specific diameter and it
would make sense for Airbus to use the existing investment on the A350
while at the same time inproving the materials used to make the panels.

I recall adaptable tooling as early as 1987. Computer controlled to a
variable shape. So it is possible for Airbus to have adaptable tooling.

James
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Tom Sanderson
2006-11-16 15:42:25 UTC
Permalink
"JF Mezei" <***@vaxination.ca> wrote:
> The way I read it, Airbus uses composite *parts* bolted together. Boeing
> makes a one piece fuselage plug. Changing a broken skin panel on an Airbus
> would be easier than changing a whole fuselage plug of a fully assembled
> aircraft with all the wiring passing through it.

It's basically impossible to change a whole fuselage plug. I've never heard
of it being done even on a heavy maintenance visit. You just repair the
local damage (usually with a repair doubler).

Replacement of a whole panel is highly non-trivial because the fuselage skin
is a load carrying member...when you remove it, the aircraft sags. Skin
panel replacement requires the airplane to be on jacks to hold position
while the panel is removed and the new one drilled to match.

> If the fuselage skin does not corrode (or otherwise degrade, delaminate
> etc), and the skin is an integral part of the fuselage structure (as
> opposed to some aluminium sheets rivetted onto the structure)

Even on an aluminum aircraft, the skin is an integral part of the structure.
The skin carries all the pressurization load and all the torsion load, as
well as stabilizing the stringers.

> On the other hand, by having separate panels, Airbus may be able to use
> carbon fabric instead of laying tape since for smaller parts, it is much
> easier to use fabric to conform to the desired shape. **IF** this allows
> for lighter panels due to smaller number of layers, then Airbus *might*
> have an advantage.

There's no way to make a fabric panel as light as a tape one, that I know
of. Virtually all the strength of a composite comes from the fibers. The
fiber content of a good composite is pretty much the same for cloth or tape,
so what determines how much composite you need is how closely you can align
the fiber direction with the load direction. I don't see any way you can
make a cloth part have a more optimal fiber layout than a tape part.

> But somehow, I suspect that Boeing's one-piece design will end up better
> since it would bond the skin to the ribs in a more effective way than
> rivets or whatever Airbus plans to use.

Right now, Airbus uses one piece skin-stringer panels. I would guess they'd
do the same thing with composites. The frames would still be separate, as
they are on the 787, I believe.

> With more and more airlines willing to outsource aircraft maintenance, it
> becomes easier for a few maintenance shops to buy fancy equipment to do
> major maintenance/rebuilds of fuselage parts.

Ramp rash is something that happens, there's no way to avoid it, and you
need to be able to deal with it and keep the plane in service...no operator
will accept requiring a major repair visit for a little hole or dent in
their fuselage.

> HOWEVER, there is the potential for some neat stuff though. Consider that
> by building smaller pieces, Airbus *might* be able to make window frames
> integral to the fuselage skin and this might give it some weight advantage
> compared to Boeing's separate window frames which are riveted to the skin.

I doubt an integral window belt will save more weight than all those splices
between panels, but Airbus has some good technical people of their own so it
will be interesting to see how they handle it. FYI, I don't think anything
composite on the 787 is rivetted. For one thing, you can't put aluminum in
direct contact with carbon fiber and, for another, I don't think composites
can take the stress of riveting. All the stuff I've seen uses Hi-Loks or
something like them.

Tom.
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Tom Sanderson
2006-11-16 15:26:11 UTC
Permalink
"jbaloun" <***@yahoo.com> wrote:
> It sounds like Airbus is going around bad-mouthing Boeing's one-piece
> composite fuselage design. We may be hearing more about repairability
> from Airbus as the A350 gets going. This approach may backfire if
> Boeing clearly demonstrates that they have an easy, low cost and
> reliable method of repairing the 787 fuselage because if they don't
> Boeing will surely throw R/D money at the problem until the do.

Boeing has been saying that repairing will be as easy, if not more so, than
existing fuselages. I'm not exactly sure how the details of that work, but
they made the commitment a long time back so I think you're right that, if
they can't do it already, they'll work until they can.

> It is possible that Airbus does in fact have a cost-effective way of
> laying up panels. Maybe even to the point that it will not cost much to
> simply replace a damaged panel rather than repair it. Just keep a panel
> layup machine warmed up and when a call comes in for a replacement,
> cook one up and ship it out AOG.

I don't think the operators would go for that...ramp rash is not something
that's supposed to make you AOG for days...it should be fixable on that
night's hanger visit.

Tom.
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jbaloun
2006-11-16 06:22:14 UTC
Permalink
Paul G. wrote:
> In the Seattle Times today, during an interview with John Leahy of
> Airbus

Thanks Paul,
If I have this correct, it appears there is an article and an in depth
interview (which I have not yet read)

http://seattletimes.nwsource.com/html/boeingaerospace/2003431189_leahy15.html

http://seattletimes.nwsource.com/html/businesstechnology/2003431623_leahyweb15.html

James
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jbaloun
2006-11-16 06:50:40 UTC
Permalink
jbaloun wrote:

>From John Leahy

"If that were a market for 1,000 airplanes, and we lost 400, that would
be devastating. If it's a market for 6,000 airplanes, which we think it
can be over a 20-year period, especially when you start looking up to
the A350-1000 [which competes against the 777], then you've got a
situation where the first 400 lost are extremely disappointing but not
critical."

"I'm not in an order race with Boeing. Which is what you would say if
you were several hundred orders behind.

"We've really been looking at the 40 to 60 percent market-share range.
... We want a duopoly that's stable. ...

"When all is said and done, I think you'll see Airbus sitting between
40 percent and 60 percent of the market for the next five or six years.
The last five years, we were above 50 percent.

"Will we be slightly below? I don't think it matters whether we are
slightly below or slightly above."

**************
Sure sounds like 'sour grapes' to me. They didn't want those sales
anyway. But they sure were bragging when they were rising above 50%
market share.

Compare his comments:

"Boeing has much more of a need to look at single aisle than we do."

and

"We got caught napping on the 787. Don't expect we're going to fall
into that trap twice. We're watching what the level of technology is.
... A whole new generation of engines has to be developed."

******************
Does this imply that Airbus feels comfortable letting Boeing take the
first shot at a 737 replacement while Airbus carries the A320 family
for a few more years? Maybe the A320 is better than the 737 today but I
suspect Boeing is going to do their best to plow all the lessons
learned from the 787 into the 737 replacement and make their second
composite airframe even better if at all possible.

Also Leahy comments that the A350-1000 will be better than the 777-300
is today. Watch out Airbus, the goal-posts in this game tend to shift.
Boeing will continue to improve their products and may look forward to
a composite replacement for the 777 some years after the A3510 flies.

Meta:
Look at these times as either the aircraft manufactureres are shuffling
the deck or this is an earthquake in the air transport market. Either
way, these changes are going to ripple through the market like
after-shocks for a good decade to come.

James
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JF Mezei
2006-11-16 07:47:18 UTC
Permalink
jbaloun wrote:
> Does this imply that Airbus feels comfortable letting Boeing take the
> first shot at a 737 replacement while Airbus carries the A320 family
> for a few more years?

The way I see it, Airbus will let Boeing drive the engine manufacturers to
develop a new engine for the 737 replacement. Once they are ready to
produce a new engine with significant performance advantage, Airbus hope to
be able to jump in and not let Boeing take a lead similar to what happened
with the 787.

In the end, it is to Airbus' advantage to have engine manufacturers delay
the development of a new engine as long as possible. This not only delays
the need for Airbus to invest into a new aircraft, but also extends the
time period where Airbus has at least one plane that competes well against
the equivalent Boeing product.


QUESTION:

When Boeing announced the 7E7, it also announced GE would proproducting a
new GEnx engine. Was this a closely guarded industrial secret, or had
Airbus been made aware of GEnx long before Boeing announced the 7E7 ?

I.E. could the existance of a new 737 class engine be kept from Airbus so
that Boeing can announce a new 737 before Airbus even begins to think about
concepts for an A320 replacement ?

> is today. Watch out Airbus, the goal-posts in this game tend to shift.
> Boeing will continue to improve their products and may look forward to
> a composite replacement for the 777 some years after the A3510 flies.

While the move from aluminium to plastic may bring significant
changes/advancements, I have to wonder if, once the 787 is built,
subsequent aircraft will see major/significant improvements with regards to
aircraft structures.

I think you may see improved molding tehcniques that allow more complex
carbon fibre structures to be made as a single piece and this would save
weight.

If Airbus' decision to go with separate panels instead of single piece
fuselage ends up being inferior, then the 350 V4.0 will also be inferior to
a carbon fibre 777. But one must wonder if Boeing will replace the 777
or just grow the 787. Since the 787 is able to have 9 across seating, the
777's wider/higher cross section ends up being bigger/heavier than
absolutely necessary.

Airbus reminds me of the Bombardier LRC train. Bombardier designed it to be
as conventional as possible so that existing railway maintenance people,
used to working on 1950s trains could work on the 1980s LRC trains. So
instead of using electronics to control banking of cars, they used old
mechanical relays. For aerodynamic purposes, they had a cowling on the
undersides, which blocked access by maintenance crews. There were a lot of
compromises which may have looked good on paper, but which turned out to
actually make the product worse than conventional 1950s equipment. And
highly unreliable. (the initial glitches on the LRCs were far worse than
the A320' glitches - we're talking about wheels falling off, outside doors
opening at speed, and not opening when at stations, cars making people sea
sick because they were constantly banking from left to right etc etc).


The fixes, for the second batch of LRCs to be delivered was to dump the old
relays and introduce electronics. And that also involved VIA Rail building
a specialised maintenance facility and forget about using people trained to
maintain 1950s cars. The new facility had a proper design to allow access
from under the cars, proper tooling and proper training. This greatly
improved the reliability of at least the passenger cars which are still in
service today.

To bring this into the current context, I think that Airbus' mentality may
end up like the first batch of LRCs. Trying to emulate old stuff with new
technology may not be the right answer. Once the airline agrees to change
the way it maintains aircraft and get the proper tooling and training, then
it may be very worthwile to go all out and really adopt the new technology
and drop old ways.
.
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Tom Sanderson
2006-11-16 15:04:18 UTC
Permalink
"Paul G." <***@yahoo.ca> wrote:
> Can anyone comment on the viability/desirability of Airbus's approach
> to a composite fuselage as compared to Boeing's with the 787?

My gut says that this is a giant cover for the fact that Airbus was ignoring
the 787 and composites for so long that they don't know how to make a
one-piece fuselage barrel.

Leahy's comments don't make sense...what he seems to be proposing is a
repair plan where they just remove the damaged panel and replace it with a
good one. However, that's equivalent to removing a fuselage skin today,
which is a *major* repair. It's never done to just fix ramp rash because it
means grounding the airplane for days. I'm not sure how Airbus is going to
sell the fact that patch repairs work on aluminum fuselages (and composite
ones, according to Boeing) but they're going to go with replacement of
panels for the A350.

If they have a lot more composite panels than an existing plane has aluminum
panels, I can see the repair advantage, but then there's a whole lot more
joints in the fuselage, which add weight and complexity to the design.

Leahy is a salesman, and this doesn't make engineering sense to me.
Something else is up.

Tom.
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Daniel
2006-11-16 21:39:51 UTC
Permalink
> If they have a lot more composite panels than an existing plane has aluminum
> panels, I can see the repair advantage, but then there's a whole lot more
> joints in the fuselage, which add weight and complexity to the design.
>
> Leahy is a salesman, and this doesn't make engineering sense to me.
> Something else is up.

Perhaps they'd have a reticulated cabin structure similar to that of a
Wellington, and the non-structural skin and window panels would then be
patched around it. Used to make for strong, light and survivable
airframes. You'd change panels without jacking up the craft then :)

More likely, it's due to processes available there within the time
frame, and served with the creative pitching.
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