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keesje
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 3:37 am

Quoting Shenzhen (Reply 17):
Amazing how AC, who had the largest order of the bunch (777s, 787s, options....), received the smallest discount, whilst the airline with the least potential for future business received the largest.

We know AC was just coming out of a bancrupt situation when they placed the big order with Boeing. The deal was financed by the US Government (IM-EX Bank) and Boeing offered to buy AC´s airbus fleet.
http://www.usatoday.com/travel/flights/2007-04-24-air-canada-787_N.htm
http://www.exim.gov/

So I guess they were compensated in other ways.

"Never mistake motion for action." Ernest Hemingway
 
Poitin
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RE: A350XWB - Back To The Drawing Board (again) Pt

Sun Jun 03, 2007 3:52 am

Quoting Zvezda (Reply 135):
Quoting Poitin (Reply 134):
Years and years ago, while I was studying psychology, we had this box that there were exactly seven ways for a rat to escape from. We were all sure of it, because we each studied the box. The first two rats found the eight and ninth ways. So you really don't need a computer to make a fool of mankind.

That's a great example. It increases my sense that a computer might accidently discover a shape that has useful aerodynamic properties.

I have no doubt that some computer, with what we use to call serendipity, will discover something we haven't thought of. I am all in favor of computer scientists playing with such ideas as evolutionary algorithms. Many years ago, in the late 1960's, I was deeply involved in what was call "information retrieval" and today we call it "google". In fact, that is how I got in the VC world and made my boss a billionaire (I told him to invest in Google when everyone else though it was nutzy). I, as the hired hand, didn't do that well, but did okay.

Right now we are playing around with "artificial intelligence" which is akin to what you are suggesting, but based more on neuronal nets than on computers. Someday one may become the pilot. We have a joke about it:

    As the passengers climb the latest airliner on its maiden flight and discover that the FA's are robots, who politely lead the passengers to their seats. Finally, when they are all seated they hear:

    "Welcome about International Flight 101, our maiden service. I am your captain, or rather the triply redundant neural network that will pilot this flight. I want to assure you that there is nothing that can go wrong .... go wrong ... go wrong ... go wrong."


Quoting Jacobin777 (Reply 141):
..certainly does exist..its called "genetic optimisations"....which is a Zvezda explained. In fact, I know Boeing does actually use it.

We actually use a very simplified version of genetic optimisation for some of our work...

As noted, it's been a while since I was at Boeing, but having seen what I saw then, I am not surprised. And I expect that there is stuff going on at Boeing Computer Services that you don't know about.
Now so, have ye time fer a pint?
 
Shenzhen
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 4:00 am

Quoting Keesje (Reply 150):
We know AC was just coming out of a bancrupt situation when they placed the big order with Boeing. The deal was financed by the US Government (IM-EX Bank) and Boeing offered to buy AC´s airbus fleet.
http://www.usatoday.com/travel/flights/2007-04-24-air-canada-787_N.htm
http://www.exim.gov/

So I guess they were compensated in other ways.

All airlines/operators based outside the USA can apply for IM/EX Bank gurantees (S7 included), which isn't US Government financing, but a loan gurantee. If Boeing did agree to purchase AC Airbus' , one thing is pretty certain, the price wasn't very good, meaning AC will do everything in their power to sell them themselves, and only rely on Boeing if they fail.

What I was trying to get across, is that the numbers listed are but a guess at what an airline received in discounts, and shouldn't be considered as anything more then that.

Cheers
 
Poitin
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 4:09 am

Quoting Jacobin777 (Reply 141):
Quoting TeamAmerica (Reply 133):

More than that Zvezda, advances in software now allow massive arrays of relatively cheap computers to be used in concert. Rather than one immensely expensive super computer, we can use literally thousands of lesser computers linked together to achieve scalable performance. Anyone who does a Google search is accessing exactly such an array - it's very powerful technology.

While I can't give details of Google, there are well over 100,000 computers involved -- almost all of them PCs. Dirt cheap computers. The secret of Google is in how they connect them. The beauty is in the way they split the inquiry into that array, get feed back from them all and return millions of hits.

This is an early paper written by the wonder kids themselves. It is their starting point. Today it much more sophisticated.

http://infolab.stanford.edu/~backrub/google.html

Google is the first massively parallel computer that not only works, but is efficient. The same technology can be used to calculate the worlds weather over a 10 km grid or aerodynamics of airplane on a one centimeter grid over the entire surface in near real-time mode.
Now so, have ye time fer a pint?
 
Wsp
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 4:44 am

Quoting NAV20 (Reply 129):
Quoting Wsp (Reply 126):
The difference is compared to previous aircraft construction methods not the A350.

So which aeroplane was Tim Clark of Emirates making the comparison with, if not the A350, Wsp?

The imaginary "old tech" airplane that Boeing uses for most of their comparisons. Probably a 767. But you are free to believe that Boeing did a comparison against the A350 that they have no detailed information about or that Clark took it upon himself to compare the confidential (and in both cases preliminary) Boeing and Airbus data and release his conclusions to the press.
 
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SEPilot
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 5:02 am

Quoting Poitin (Reply 151):
"Welcome about International Flight 101, our maiden service. I am your captain, or rather the triply redundant neural network that will pilot this flight. I want to assure you that there is nothing that can go wrong .... go wrong ... go wrong ... go wrong."


My favorite is that the cockpit of the future will contain a pilot and a dog. The pilot's job is to feed the dog; the dog's job is to bite the pilot if he touches anything.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
Poitin
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 5:24 am

Quoting Wsp (Reply 154):
The imaginary "old tech" airplane that Boeing uses for most of their comparisons. Probably a 767. But you are free to believe that Boeing did a comparison against the A350 that they have no detailed information about or that Clark took it upon himself to compare the confidential (and in both cases preliminary) Boeing and Airbus data and release his conclusions to the press.

Given that EK has a team of engineers sitting in Toulouse doing "audits" of the A380 and A350, I would have to believe Tim Clark knows what he is talking about. He iis not a A.netter, but one of the sharpest airline execs going.
Now so, have ye time fer a pint?
 
aminobwana
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 5:57 am

Quoting Wsp (Reply 154):
The imaginary "old tech" airplane that Boeing uses for most of their comparisons. Probably a 767. But you are free to believe that Boeing did a comparison against the A350 that they have no detailed information about or that Clark took it upon himself to compare the confidential (and in both cases preliminary) Boeing and Airbus data and release his conclusions to the press

Do you really believe that Boeing have not detailed information regarding the current design of the A350 they are commenting, as far it exists, or that Airbus has not the same of the B787 ??

And what means confidential info to Tim Clark ?? Of course, he must commit, as any customer, not to hand over protected design documents to competition or press, but he is free, probably obliged, to explain why he prefers and ultimately decides one of the competing designs, the shareholder expect no less !! When Tim made in the past glowing comments on the A380, nobody complained !!

And finally, what means "preliminary"" ?? The manufacturers expect a firm order basing on such design, meaning that it can only be changed with customer assent,

As for the comparison of framed composit panels ans composite barrels:

In my speciality, there is a conceptuelly equivalent problem:

You can design the control of a complex mechanism, paper machine or aircraft, applying analog or digital criteria:
when the latter appeared years ago, both competed, both were able to do the job, but today, nobody will even think to use the analog !!

aminobwana
 
MD-90
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 6:43 am

Quoting SEPilot (Reply 131):
In fact the next plane that I intend to own is a Mooney, and one of the attractions (besides its efficiency and good handling) that is very important to me is that it has a one-piece main spar that has NEVER been broken in the air. Mooney once tried to find out just how strong it was, and tested it to over 9g, whereupon their test fixture broke. Way overbuilt, but I like that in a wing spar. If you're going to put any unnecessary weight in an airplane that's where I vote to put it.

Amen. Now, if only new Mooneys were price-competitive with Cirrus and Columbia...
 
Wsp
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RE: A350XWB - Back To The Drawing Board (again) Pt

Sun Jun 03, 2007 6:59 am

Quoting Poitin (Reply 156):
Given that EK has a team of engineers sitting in Toulouse doing "audits" of the A380 and A350, I would have to believe Tim Clark knows what he is talking about. He iis not a A.netter, but one of the sharpest airline execs going.

You are putting words in his mouth. His sentence doesn't say that he is comparing with the A350. Just as the 30% quote from Boeing that I quoted does not refer to the A350.

Quoting Aminobwana (Reply 157):
Do you really believe that Boeing have not detailed information regarding the current design of the A350 they are commenting, as far it exists, or that Airbus has not the same of the B787 ??

I don't believe that any serious company would make that kind of comparison at this stage. Reading some of your posts one may come to the conclusion that Airbus is centuries away from finishing the design of the airplane. Yet you are assuming that Boeing would make reliable comparisons based on whatever information they have obtained about this design. I am not sure why you are insinuating that Boeing is that unprofessional.

But of course it is possible that Boeing is much better informed and has done comprehensive benchmarking between the two actual designs and the above paragraph is wrong. But clearly this is not what the Clark quote says. Clark did not say that the 787 provides 40% lower maintenance cost compared to the A350. And my objection was merely to NAV20 reading this into the vaguely worded quote.

Quoting Aminobwana (Reply 157):
And finally, what means "preliminary"" ?? The manufacturers expect a firm order basing on such design, meaning that it can only be changed with customer assent,

Preliminary means that maintenance intervals have to be approved by the authorities. To my knowledge that has not happened for either model yet.

Quoting Aminobwana (Reply 157):
As for the comparison of framed composit panels ans composite barrels:

In my speciality, there is a conceptuelly equivalent problem:

You can design the control of a complex mechanism, paper machine or aircraft, applying analog or digital criteria:
when the latter appeared years ago, both competed, both were able to do the job, but today, nobody will even think to use the analog !!

Clearly your statement implies that your speciality is not composite aircraft construction. Therefore I doubt that you can assess if the problems are conceptually equivalent.
 
pygmalion
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 7:42 am

Quoting Slz396 (Reply 117):

Quoting BigJKU (Reply 110):
Didn't the A380 wing break too early during test and have to have more structure added to it?

Yep, at roughly 148% of the required load and Airbus added about 7kg of reinforcements to solve the problem.

What is better you think: Design right to the edge and then finding out through static testing you have to add basically a few pounds to match the calculations, or overdesign and proudly announce your wings can take 160% of the load????



Quoting Slz396 (Reply 117):
Interesting point brought up by Sabenapilot and Kaneporta1 indeed! Thanks.

The thing that must be considered is that Airbus designed the A380 wing to get a minimum of 150% (thats the rule and they may have shot for a slightly higher number) thus they were off by 3%

As Boeing disclosed just prior to the 777 test, they expected 153.5 -154% at break... It broke at just a smidge over 154%

Which one was the better designer ... the one that failed and missed the number by at least 3% or the one that made it and got within a .5% margin of error? Shouldn't Airbus have aimed better and put the 7 kgs in BEFORE the test?? They missed a major test to save 7 kgs? Who thought that was a good design trade?

Better wing designers at Airbus? Where is the evidence?
 
zvezda
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 9:50 am

Quoting Pygmalion (Reply 160):
The thing that must be considered is that Airbus designed the A380 wing to get a minimum of 150% (thats the rule and they may have shot for a slightly higher number) thus they were off by 3%

As Boeing disclosed just prior to the 777 test, they expected 153.5 -154% at break... It broke at just a smidge over 154%

Which one was the better designer ... the one that failed and missed the number by at least 3% or the one that made it and got within a .5% margin of error? Shouldn't Airbus have aimed better and put the 7 kgs in BEFORE the test?? They missed a major test to save 7 kgs? Who thought that was a good design trade?

That was a failure of the structural FEA models (and perhaps management for not specifying a sufficient margin of error), not a failure of the aerodynamics. On the aerodynamic side, the 777 wing was designed for a cruise speed of 0.83M and everyone was surprised to find in service that 0.84M was more efficient. So, the 777 wing designers were off by 1%.

Quoting Pygmalion (Reply 160):
Better wing designers at Airbus? Where is the evidence?

That's a fair question. I see no evidence for the assertion.
 
pygmalion
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 11:41 am

It wasn't that it was more efficient at 1% over its design cruise speed of .83M, the 777 wing was still efficient at .84M... the wing had a wider band of speed for efficient cruise than was expected. You can call that a miss or better aircraft than promised.

Your choice.
 
WingedMigrator
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 12:42 pm

Quoting Pygmalion (Reply 160):
As Boeing disclosed just prior to the 777 test, they expected 153.5 -154% at break... It broke at just a smidge over 154%

The size of the statistical sample does not allow one to conclude whether the result was luck or skill. I do not believe for one second that an analytical structural model can reliably get you within half a percent of the true answer. I do not believe for one second that manufacturing variations are so small and well controlled as to stay within a half percent if you did the test several times.
 
StressGuy
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 12:59 pm

Some really funny points are espoused on this forum from time to time. In regards to SabenaPilot's reply 109, the polite thing to say is that he is full of nonsense. Boeing spent huge amounts of time and money doing trades studies on the 787 and they sure as the world didn't choose what they chose on the 787 for the reasons he claims. And in case he hasn't figured it out yet, there are lots of smart guys in Everett who made the choices due to what I am sure is a variety of reasons.

In regards to to Airbus designing better wings than Boeing, that is a bit funny too. I have heard Airbus wings referred to more than once as "big dumb wings" from people who I am confident have forgot more about aerodynamics than 99.9% of the people on this forum even know about aerodynamics. I am not saying that Airbus doesn't design good wings because they do, but to imply that they are so superior is laughable. There are plenty of areas in wing design that Airbus doesn't do quite as well as Boeing and probably vis-a-versa.

Really, there are several Airbus cheerleaders (and Boeing cheerleaders) on this forum that believe they know far more about airplane design (or how Boeings designs airplanes) than they really do.
 
zvezda
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 2:04 pm

Quoting Pygmalion (Reply 162):
It wasn't that it was more efficient at 1% over its design cruise speed of .83M, the 777 wing was still efficient at .84M... the wing had a wider band of speed for efficient cruise than was expected.

Thank you for the clarification. Getting a result different from what one expects doesn't mean the designers are at fault; it means the models need refinement.
 
astuteman
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 5:04 pm

Quoting WingedMigrator (Reply 163):
I do not believe for one second that manufacturing variations are so small and well controlled as to stay within a half percent if you did the test several times.

Not on an assembly as complex as a wing (well, a metallic one anyway - it's interesting to ask the question as to whether CFRP wing construction will be a more "controllable" process......)

Quoting StressGuy (Reply 164):
I have heard Airbus wings referred to more than once as "big dumb wings" from people who I am confident have forgot more about aerodynamics than 99.9% of the people on this forum even know about aerodynamics.

Big dumb wings or big dumb people?
Whilst I don't subscribe to the "Airbus wipes the floor with Boeing on wing design", the A380 and A350 wings will be (are) pretty much state-of-the-art, and optimised to satisfy the criteria they were designed for in a way that I don't consider Boeing could beat.
You might get into some debate about whether the design criteria were correct (e.g. why does the A380 wing have to be capable of supporting MTOW growth beyond 625t), but given the instruction to design a wing that can support 625t, AND an 80m wingspan constraint, AND the constraint of a location in the aircraft much lower down than is usual, because of the existence of the lower deck, then the A380 wing, as designed, is pretty much what Boeing, or any competent other would have come up with.......
I presume you, as a structural engineer, understand that the inputs, and outcomes, of a process like wing design, are far more complex than "big, dumb people" might understand, looking from the outside.

Regards
 
zvezda
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 5:12 pm

Quoting Astuteman (Reply 166):
the A380 and A350 wings will be (are) pretty much state-of-the-art, and optimised to satisfy the criteria they were designed for in a way that I don't consider Boeing could beat.

Apparently, I have more faith in progress than you do. I expect the 787 wing to be better than the WhaleJet wing, I expect the A350 wing to be better than the 787 wing, and I expect the Y1/737RS wing to be better than the A350 wing.
 
astuteman
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 6:58 pm

Quoting Zvezda (Reply 167):
Apparently, I have more faith in progress than you do. I expect the 787 wing to be better than the WhaleJet wing, I expect the A350 wing to be better than the 787 wing, and I expect the Y1/737RS wing to be better than the A350 wing.

To be fair, in my own mind "State-of-the-art" meant "at that time".
Like you, I would expect incremental improvements if, for example, Airbus designed the A380's wing today.
My point was, given the constraints, I would have expected Boeing to come up with near-on exactly the same "big, dumb wing" that Airbus did at that time.........

Hope that helps.

Regards
 
Pihero
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 7:13 pm

Quoting StressGuy (Reply 164):
I have heard Airbus wings referred to more than once as "big dumb wings" from people who I am confident have forgot more about aerodynamics than 99.9% of the people on this forum even know about aerodynamics. I am not saying that Airbus doesn't design good wings because they do, but to imply that they are so superior is laughable.

Then you could have a look at this NASA study :
http://ntrs.nasa.gov/archive/nasa/ca...asa.gov/19960052267_1996080955.pdf
Then come back to explain how dumb these NASA engineers are comparing both manufacturers' solutions.
There is dumb and there is also excessive nationalism...which doesn't go towards objective reasoning and gets content with hearsay.

Regards
Contrail designer
 
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autothrust
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RE: A350XWB - Back To The Drawing Board (again) Pt

Sun Jun 03, 2007 9:34 pm

Quoting Pihero (Reply 169):

Then you could have a look at this NASA study :

Thanks Pihero for sharing, i took a look though i dont understand most but found this statements:

Quote:


Technology level, however, does not answer the question why contemporary airplanes like the
Boeing 777 and the Airbus A330/340 do not have similar performance; i.e., why the Airbus
airplanes are doing better with simpler high-lift systems. The reason is not easily explained, and
any attempt to do so is...

Only the Douglas DC-9 and MD-80
and the Airbus A320 and A330/340 airplanes can claim a clean record of three "Nos."

The evolution of increasingly simple high-lift systems at Airbus was probably even more spectacular.
Within 20 years, Airbus developed from double-slotted flaps to all single-slotted flaps on their
new models (A321 is the exception), without any reduction in landing lift coefficients. At the same
time, they have made gains in takeoff and landing L/D.

The benefits of evolving from complex to simpler high-lift systems are obvious, but they are not
easy to quantify. The following statements qualify the potential performance and/or design
improvements that can be expected:

• Simpler systems are generally lighter, and the weight reduction can be used to increase useful
load.
• The improved takeoff L/D of simpler high-lift systems can be used to increase takeoff weight by
adding either payload or fuel.
• The improved landing L/D reduces airframe noise and allows a lower engine power setting,
which also reduces noise.

That such good wing aerodynamics
and structural designs have emerged can probably be attributed to the decision to leave the airfoil
and wing box design almost exclusively to British Aerospace and the high-lift system design to
Deutsche Aerospace (DASA).

Many experts in the field believe that Airbus has actually overtaken Boeing in several airplane
technologies, especially in high lift. Therefore, the race is essentially between Boeing and Airbus.
Douglas and Lockheed may have new high-lift technology available to them, but it is not visible
because it is not in use.



Very interesting.

[Edited 2007-06-03 14:42:00]
Flown on: DC-9, MD-80, Fokker 100, Bae 146 Avro, Boeing 737-300, 737-400, 747-200, 747-300,747-400, 787-9, Airbus A310, A319, A320, A321, A330-200,A330-300, A340-313, A380, Bombardier CSeries 100/300, CRJ700ER/CRJ900, Embraer 190.
 
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Revelation
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RE: A350XWB - Back To The Drawing Board (again) Pt

Sun Jun 03, 2007 9:57 pm

Quoting Astuteman (Reply 166):
Big dumb wings or big dumb people?

Come now - that kind of jibe doesn't become you at all.

As you know, one group of designers can come up with what is deemed to be "inferior" to another for a whole host of reasons other than their intellegence. Usually these are related to how much money the company is willing to spend to optimize the design.

Also "inferior" depends on the criteria you use to judge the two solutions. One group may have been tasked to optimize for cost of manufacture, time of manufacture, maintanability, lifespan, etc. rather than absolute performance.

Quoting Astuteman (Reply 166):
Whilst I don't subscribe to the "Airbus wipes the floor with Boeing on wing design", the A380 and A350 wings will be (are) pretty much state-of-the-art, and optimised to satisfy the criteria they were designed for in a way that I don't consider Boeing could beat.

On what basis are you making this statement?

Quoting Pihero (Reply 169):
Then you could have a look at this NASA study :
http://ntrs.nasa.gov/archive/nasa/ca...asa.gov/19960052267_1996080955.pdf
Then come back to explain how dumb these NASA engineers are comparing both manufacturers' solutions.

A ten year old study focusing mainly on the high-lift devices isn't really addressing the thrust of the discussion here, IMHO.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
bigjku
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 10:05 pm

Quoting Pihero (Reply 169):
Then you could have a look at this NASA study :
http://ntrs.nasa.gov/archive/nasa/ca...asa.gov/19960052267_1996080955.pdf
Then come back to explain how dumb these NASA engineers are comparing both manufacturers' solutions.
There is dumb and there is also excessive nationalism...which doesn't go towards objective reasoning and gets content with hearsay.

Yeah, this is an article talking about high lift structures on a wing and it is ten years old. The basics of it seems to be that Airbus designs a system that provides equally as good high lift during takeoff and landing as a more complicated Boeing system. I believe the 787 adopts a lot of these advances.
 
slz396
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 10:13 pm

Quoting Wsp (Reply 159):
Reading some of your posts Aminobwana, one may come to the conclusion that Airbus is centuries away from finishing the design of the airplane. Yet you are simultaneously assuming that Boeing would make reliable comparisons based on whatever information they have obtained about this very same design. I am not sure why you are insinuating that Boeing is that unprofessional.

 rotfl 

Talking about using his very own arguments against him....

Quoting Pihero (Reply 169):
have a look at this NASA study, StressGuy.

From the NASA study:

It does not answer the question why contemporary airfoils like on the Boeing 777 and the Airbus A330/340 do not have similar performance; i.e., why the Airbus airplanes are doing better with simpler high-lift systems. The reason is not easily explained, and any attempt to do so is politically charged, but the author presents some facts and opinions in the following paragraphs.

Quoting Pihero (Reply 169):
There is dumb and there is also excessive nationalism...which doesn't go towards objective reasoning and gets content with hearsay.

Indeed.

I don't know what Kanaporta1 or Sabenapilot were hinting at, but it does seem NASA too agrees Airbus is generally designing 'better' wings than Boeing, whatever 'better' may mean. Also interesting to note that better doesn't automatically mean the second best is a moron, like some here have repeatedly mentioned and then taken insult on, although it hasn't been mentioned in either form be either of the 2 above mentioned members who's assessment of skills seem to coincide with the NASA study which I do take a bit more serious than just hearsay about 'big dumb wings'.
 
baroque
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 10:19 pm

Quoting Pihero (Reply 169):
Then you could have a look at this NASA study :
http://ntrs.nasa.gov/archive/nasa/ca...5.pdf

Very interesting Pihero, and most illuminating. P149 suggests NASA might agree with some of the posts in this thread, although their conclusions are restricted to high lift devices. It is a bit dated, but does seem to give rather high marks to Airbus on that aspect of design.

The explanation of how wing design is allocated within Airbus is also interesting and stresses that the wings as such are a collaborative effort between two of the supposedly warring nations.

I guess we can assume that NASA is not totally wrong.  pray 
 
Poitin
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RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 10:26 pm

Quoting Wsp (Reply 159):
Quoting Poitin (Reply 156):
Given that EK has a team of engineers sitting in Toulouse doing "audits" of the A380 and A350, I would have to believe Tim Clark knows what he is talking about. He iis not a A.netter, but one of the sharpest airline execs going.

You are putting words in his mouth. His sentence doesn't say that he is comparing with the A350. Just as the 30% quote from Boeing that I quoted does not refer to the A350.

No, he said that "40% less maintenance is compelling". That is the quote. That would have to assume ALL aircraft in the competition, whatever they may be. That man said what he said apparently in English, was quoted in the same tongue and not subject to misinterpretation as you protest.
Now so, have ye time fer a pint?
 
slz396
Posts: 1883
Joined: Tue Oct 02, 2001 7:01 am

RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 10:31 pm

Quoting BigJKU (Reply 172):
The basics of it seems to be that Airbus designs systems that provides equally as good high lift during takeoff and landing as a more complicated Boeing system.

So to translate it:
one manufacturer needs to make use of a more complicated design to achieve the same as the other in a specific domain.

If we look at the discussion regarding the composite fuselages of both the A350 and 787, isn't it precisely the simplicity of the barrel approach over the shell approach which gets applauded as the big differentiator by the Boeing cheerleaders, not so much because it has any performance benefits (through a lower EOW), but because there will be low maintenance costs resulting from it?

Then I do find it strange the same argument when applied to the wings suddenly is found irrelavant by those same people...

Quoting Revelation (Reply 171):
It is a ten year old study.



Quoting BigJKU (Reply 172):
it is ten years old.

Indeed, but just how many all new high lift devices did Boeing design in the mean time?

Supposing one can only gain truly innovative knowledge from experience, I'd say that although the study is 10 years old, its conclusions are likely still valid.

Quoting BigJKU (Reply 172):
I believe the 787 adopts a lot of these [Airbus] advances.

I'd hope so, although that can hardly be called innovating on that front then, don't you agree?

It all seems to confirm what was suggested by 2 Airbus insiders: although the fuselage of the 787 is innovative, the 787 wing is pretty conservative (at least from an Airbus point of view) and so far I haven't really seen anything to contradict these statements from either Boeing or any member on this site, quite on the contrary even...
 
astuteman
Posts: 7086
Joined: Mon Jan 24, 2005 7:50 pm

RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 10:37 pm

Quoting Revelation (Reply 171):
Come now - that kind of jibe doesn't become you at all.



Quoting Revelation (Reply 171):
As you know, one group of designers can come up with what is deemed to be "inferior" to another for a whole host of reasons other than their intellegence. Usually these are related to how much money the company is willing to spend to optimize the design.

Also "inferior" depends on the criteria you use to judge the two solutions. One group may have been tasked to optimize for cost of manufacture, time of manufacture, maintanability, lifespan, etc. rather than absolute performance.

Whilst criticising my "jibe", you actually make EXACTLY the same point that I was.
Namely, it's not appropriate to label Airbus wings "big, dumb wings", no matter how knowledgeable you might be with regard to aerodynamics, UNLESS you are aware of the "whole host of reasons other than intelligence" that influenced the design of those wings.

Said "jibe" (if that's what you think it was) stands

Regards
 
Wsp
Posts: 356
Joined: Sun May 06, 2007 7:43 am

RE: A350XWB - Back To The Drawing Board (again) Pt

Sun Jun 03, 2007 10:48 pm

Quoting Poitin (Reply 175):
No, he said that "40% less maintenance is compelling". That is the quote. That would have to assume ALL aircraft in the competition, whatever they may be. That man said what he said apparently in English, was quoted in the same tongue and not subject to misinterpretation as you protest.

I cannot see where in his quote he is detailing what he is comparing the maintenance levels to. It could be older aluminum aircraft it could be the A350 it could be his uncle's private Cessna it could be all aircraft ever built it could even be all methods of transportation ever devised or it could be a bicycle. The lack of something doesn't automatically mean that you can deduce whatever meaning suits your argument. Unless that is a specific linguistic property of the English language that I am not aware of.

We can only hope that when we finally get reliable numbers on the 787 vs A350 maintenance cost comparison you will not use this quote and claim that Clark has misinformed the public.

[Edited 2007-06-03 16:10:33]
 
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Revelation
Posts: 22948
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RE: A350XWB - Back To The Drawing Board (again) Pt

Sun Jun 03, 2007 10:53 pm

Quoting Astuteman (Reply 177):
Whilst criticising my "jibe", you actually make EXACTLY the same point that I was.

Cheers, mate, we are on the same side. It just wasn't clear to me which people you were referring to as "dumb".

And if it isn't clear, I have a lot of respect for both Airbus and Boeing's designers. I don't think Airbus builds "dumb" wings, and whomever said that doesn't know what they are talking about.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
pygmalion
Posts: 836
Joined: Thu Jun 29, 2006 12:47 am

RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 10:57 pm

it is common knowledge that Boeing optimises for cruise and then tries to get good takeoff and landing performance with complicated lift devices. Airbus seems to optimize for a different section of the flight profile. Since a good wing would capture these aspects and many, many more... No one has made any arguments here that either Boeing or Airbus makes better wings. Saying Airbus does due to its nifty flaps and slats... leaves out lots of other factors. Saying Boeing does because of slightly higher cruise speeds is equally as false.

All I have tried to do here is point out where the arguments are incomplete or just missing the big picture. Airplanes are large flying collections of design choices. Millions of design hours full of choices, all made in good faith to meet varying business constraints. Both companies build good aircraft.

I will repeat one comment for clarification... we design (and yes I am an aircraft engineer for Boeing) to much better than within a few percent, the right answer would be within hundredths of a percent. The data and structural allowables are layed out to have a floor. All the calculations and stats are structured to give an "At least this good" type of value and they do include part and people variation and yes that takes lots and lots and lots of data to get good sample sizes. The data says that we are this good or better based on a very robust study. When you collect large collections of different design details the uncertainty of the collection grows but by a calculable value.

When AirBus broke the wing early that surprised a lot of designers.., it should never be less than Ultimate load, ever. That is a mantra that is never violated by any aircraft engineer. If you are at all uncertain, then you err above the line. To just wave your hand and imply that its not possible to get within 2-3% so why would any one blame Airbus if they missed by that much is just plain crap. If the models are only good within 3% then you aim for 3 percent over. Boeing aimed at 103.5%. That was a design choice based on understanding the possible uncertainty. A choice that I appreciate as a passenger.
 
bigjku
Posts: 1906
Joined: Sat Feb 17, 2007 10:51 pm

RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 11:02 pm

Quoting Slz396 (Reply 173):
I don't know what Kanaporta1 or Sabenapilot were hinting at, but it does seem NASA too agrees Airbus is generally designing 'better' wings than Boeing, whatever 'better' may mean. Also interesting to note that better doesn't automatically mean the second best is a moron, like some here have repeatedly mentioned and then taken insult on, although it hasn't been mentioned in either form be either of the 2 above mentioned members who's assessment of skills seem to coincide with the NASA study which I do take a bit more serious than just hearsay about 'big dumb wings'.

I think the basic argument is that Airbus was designing wings with good high lift devices that were simpler than the systems Boeing was using at the time. I don't think anyone would argue with this assessment. The article does not seem to really get directly into the efficiency of the wings at cruise and certainly a more complex flap system has not seemed to hurt Boeing that badly.

Quoting Slz396 (Reply 176):

If we look at the discussion regarding the composite fuselages of both the A350 and 787, isn't it precisely the simplicity of the barrel approach over the shell approach which gets applauded as the big differentiator by the Boeing cheerleaders, not so much because it has any performance benefits (through a lower EOW), but because there will be low maintenance costs resulting from it?

Certainly Boeing deserves criticism for not designing as simply of flaps as Airbus but also consider this article was written in 1996. Since then Boeing has put the 737NG, the 777ER/LR and the 787 into production. At the time of the article they were competing with a product lineup where the 777 was about the only new thing in their lineup and the article is pretty complimentary of the 777 high lift systems.
 
astuteman
Posts: 7086
Joined: Mon Jan 24, 2005 7:50 pm

RE: A350XWB - Back To The Drawing Board (again) Pt 2

Sun Jun 03, 2007 11:03 pm

Quoting Revelation (Reply 179):
Cheers, mate, we are on the same side. It just wasn't clear to me which people you were referring to as "dumb".

Many thanks, Friend.
FWIW I have a bit of a bee in my bonnet about over-simplified viewpoints or statements that have a habit of cropping up on A-net.
My experience of complex engineering to date has been that the number of constraints that one works under are huge, and that circumstances are usually WAY more complicated than they might appear to the uninitiated.
Hence the comment - sorry, jibe  Smile

Regards
 
ikramerica
Posts: 15059
Joined: Mon May 23, 2005 9:33 am

RE: A350XWB - Back To The Drawing Board (again) Pt 2

Mon Jun 04, 2007 3:01 am

Quoting Pygmalion (Reply 180):
That is a mantra that is never violated by any aircraft engineer. If you are at all uncertain, then you err above the line.

Thanks for the explanation.

This goes back to my argument with astuteman (I believe it was him) when it happened.

He claimed everyone erred on the side of safety. I said that for the wing to fail below the design load of the test, it demonstrated that Airbus did not, in fact, err on the side of safety. Had they done so, they would have designed for 103.5% as you state and thus even to be off by 3%, it still would have passed. So either Airbus erred on the side of cost/weight, or they just F-ed up altogether and designed for 103.5% and still missed it! If the former, fine, fix it later, but don't tell me that they are really doing everything based on safety first. If the latter, their 'calculated' retest should be suspect because they were so far off on the real test.

What this has to do with the A350X, I don't know...  Wink
Of all the things to worry about... the Wookie has no pants.
 
Poitin
Posts: 2651
Joined: Wed Jan 25, 2006 6:32 am

RE: A350XWB - Back To The Drawing Board (again) Pt 2

Mon Jun 04, 2007 3:25 am

Quoting Wsp (Reply 178):
We can only hope that when we finally get reliable numbers on the 787 vs A350 maintenance cost comparison you will not use this quote and claim that Clark has misinformed the public.

The man said what he said. Take it as a comparison with steam locomotives, if you want. The rest of us see it for what it is -- the opinion of a knowledgeable insider. He could be right and he could be wrong, but at this point I would have to accept it as "well informed" even if you don't.
Now so, have ye time fer a pint?
 
Wsp
Posts: 356
Joined: Sun May 06, 2007 7:43 am

RE: A350XWB - Back To The Drawing Board (again) Pt 2

Mon Jun 04, 2007 4:13 am

Quoting Poitin (Reply 184):
The rest of us see it for what it is -- the opinion of a knowledgeable insider.

Speak for yourself and don't drag others into your arguments.

Quoting Poitin (Reply 184):
He could be right and he could be wrong, but at this point I would have to accept it as "well informed" even if you don't.

I never questioned that he is well informed. If you can't read my replies then just avoid replying altogether. Unless you are misreading them on purpose.
 
StressGuy
Posts: 13
Joined: Mon Apr 02, 2007 9:34 am

RE: A350XWB - Back To The Drawing Board (again) Pt 2

Mon Jun 04, 2007 8:59 am

In regards to the NASA report, I absolutely agree that Airbus does design excellent high-lift devices. High lift devices are only part of a wing though. There are lots of important parts of designing a wing such as integrating the engines onto the wing which Boeing does very well among other things. Anyway I want to be clear that I am not being critical of Airbus' wing designs, I just believe that to claim that Airbus designs wings that are "better" than the ones that Boeing designs speaks of a lack of knowledge on the subject. It is far too complex of a subject to make statements like that. Wing design is all about compromises and how all of the aspects get put together, and Airbus does some things very well just like Boeing does some aspects of it very well.
 
WingedMigrator
Posts: 1771
Joined: Wed Oct 26, 2005 9:45 am

RE: A350XWB - Back To The Drawing Board (again) Pt 2

Mon Jun 04, 2007 12:18 pm

Quoting Pygmalion (Reply 180):
we design (and yes I am an aircraft engineer for Boeing) to much better than within a few percent, the right answer would be within hundredths of a percent.

No.

Quoting Pygmalion (Reply 180):
If the models are only good within 3% then you aim for 3 percent over.

Yes.
 
Shenzhen
Posts: 1666
Joined: Wed Jun 25, 2003 12:11 pm

RE: A350XWB - Back To The Drawing Board (again) Pt 2

Mon Jun 04, 2007 1:36 pm

Designing an airplane is a compromise. The aero guys want one thing, the structures another. One would like it as lite as a feather, whilst the other as strong as a tank.

Cheers

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