airA380
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Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 05, 2006 12:03 am

http://en.wikipedia.org/wiki/A350#Specifications

I just looked at the a350 empty weight 130.7t while 787-9 115.3t when a359 is only 2m larger than 787-9

difference of weight 15.4t. Why?

Both company have highly expert people working. so Whats gone Wrong, why is a359 so heavy.
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RichardPrice
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 05, 2006 12:27 am

Composite vs Traditional materials, at a guess.
 
kaddyuk
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 05, 2006 1:31 am

Quoting RichardPrice (Reply 1):
Composite vs Traditional materials, at a guess.

The A359 is still made from mostly aluminium & composite material where the 797 is made from a completely composite fuselage...
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Grbld
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 05, 2006 3:52 am

The A359 is slightly bigger, also has bigger wings. Checking those stats however, it looks like the 787-9 has a distinct advantage. About the same size, more payload, longer range, faster cruise, lower price, lower operating costs. Not bad!
 
katekebo
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 05, 2006 3:58 am

Several reasons, being the two main ones:

1) Composite vs. metal fuselage - the material is not only lighter, but it also enables different manufacturing techniques which allow to optimize the shape / geometry to achieve desired mechanical characteristics while minimizing material usage, as well as composites can be optimized to display different strength in different directions vs. metal which basically has same strength in all direction.

2) Bleedless engines - cables are lighter than air ducts (for an equivalent amount of energy transferred over the same distance).
 
airA380
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 05, 2006 4:29 am

Quoting Katekebo (Reply 4):
Several reasons, being the two main ones:

Thanks for your answer. There must other things that counts for the weight in excess of 15.4t....that is huge amount. Why on earth airbus would build somthing that heavy to compete with 787-9. I don't know please shead some light. cheers
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katekebo
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 05, 2006 7:24 am

Also, 787 is a new, clean-sheet design, using latest state-of-the-art design technologies (computer-aided engineering and simulation), materials and engineering know-how. The 350 is a compromise design which includes elements from a 30-years old fuselage (a legacy of A-300) and 15 years old wing (from A-340 and A330).

For sure Airbus engineers are capable of designing a lighter airplane that could match Boeing design (or even beat it, taking into account the progress made in materials and design technologies over the last few years), but:
1) it would cost more to develop
2) it would come to the market even later
than the A350, which is already at schedule disadvantage with the 787.

Airbus management decided that going with a less perfect airplane, but cheaper in terms of development cost and shorter delivery time, is their best option to compete with Boeing's new plane. Also, during the last few years Airbus technical resources were fully absorbed with the A380 and A400 projects. Only time will tell if this was a right business decision.
 
eilennaei
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Thu Apr 13, 2006 7:47 am

Quoting Katekebo (Reply 6):
using latest state-of-the-art design technologies (computer-aided engineering and simulation), materials and engineering know-how.

Meanwhile, in Elbonia .... I read the Concorde was the last project on this side of the Pond that was drawn on traditional sheets.

[Edited 2006-04-13 00:50:15]
 
dw747400
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Thu Apr 13, 2006 8:07 am

Quoting Eilennaei (Reply 7):
Meanwhile, in Elbonia .... I read the Concorde was the last project on this side of the Pond that was drawn on traditional sheets.

They may have used some CAD on the A320, A330, and A340 families, but none of them were paperless deisgns. The 777 is the first totally paperless airliner. I'd imagine all subsequent deisgns, incluiding the A380, followed its lead, though I don't have any specifics on that.
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WingedMigrator
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Thu Apr 13, 2006 12:02 pm

Quoting Dw747400 (Reply 8):
The 777 is the first totally paperless airliner. I'd imagine all subsequent deisgns, incluiding the A380, followed its lead, though I don't have any specifics on that.

Yup. The CAD software used for the 777 was even (gasp!) French.  Big grin

I share AirA380's wonder at the weight difference. It would be great to see a breakdown by major components, to see if all that extra weight is just in the fuselage, or spread around a bit more...
 
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zeke
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 19, 2006 1:21 am

Quoting Dw747400 (Reply 8):
They may have used some CAD on the A320, A330, and A340 families, but none of them were paperless deisgns. The 777 is the first totally paperless airliner. I'd imagine all subsequent deisgns, incluiding the A380, followed its lead, though I don't have any specifics on that.

Think you will find that is incorrect, Airbus has been using CATIA and ICAD for a long time, Boeing saw how good it was and started using it. CATIA as a product has grown, I knew it as CATINI, the version that is about now has a lot more features.

It was a very advanced product for its time, piping, robotics, FEM, CFD, composites. Remember having CATIA models going straight to the NC machine to cut aluminum parts, I think on the 787, you would have CATIA model driving the robotic composite layups.

Airbus had to use CATIA as they had worldwide manufacturing plants that had the electronic models delivered to enable the correct manufacturing tolerances to be used.
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dw747400
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 19, 2006 2:02 am

Airbus used CAD systems for portions of the aircraft--some components were still designed in conventional ways. The 777 was designed entirely with CATIA. I'm not sure what portion of the A330/A340 was done on computer (could be 90% for all I know) but it wasn't 100%.
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Matt72033
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 19, 2006 2:25 am

Quoting Kaddyuk (Reply 2):
797 is made from a completely composite fuselage...

WOW....797? do you know something we dont?  Wink
 
widebodyphotog
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 19, 2006 3:07 am

Quoting AirA380 (Reply 5):
Thanks for your answer. There must other things that counts for the weight in excess of 15.4t....that is huge amount. Why on earth airbus would build somthing that heavy to compete with 787-9. I don't know please shead some light. cheers

Welcome to my world so to speak...this is a question I ask about this and other comparable Airbus to Boeing products...But this difference is nothing compared to the structural weight difference between A345 and 7772LR...23.3t or more than 50,000lbs and they are basically the same seating capacity, cabin area, and made of the same stuff!

In the case of the A350-9 and 787-9, not only is the 787-9 15t lighter, but also has a slightly higher useful load capability. So the two airplanes are designed to carry the same weight of stuff, fuel/payload, but the Airbus has to carry an extra 34,000lbs of dead weight on top of that. To put that amount of weight in perspective, it is just about the same as an empty, complete class 8 tractor-trailer unit, (18 wheeler)!

Even worse situation for 777-200LR against A340-500...For that 50,000lbs+ of aircraft metal you get an airplane with 6,000lbs less useful load. These are two airplanes designed to do basically the same thing...

I am not as familiar with Airbus airframe construction principles as I am with Boeing's, but I must assume that within Airbus, building light weight airframes has some level of priority???


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lightsaber
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 19, 2006 4:10 am

Quoting Widebodyphotog (Reply 13):
I am not as familiar with Airbus airframe construction principles as I am with Boeing's, but I must assume that within Airbus, building light weight airframes has some level of priority???

As the rest of the industy, a lighter airframe is worth more. About $500/kg.

Lightsaber
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Pihero
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 19, 2006 5:25 am

This is a more recent table from answers : new table
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Matt72033
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 19, 2006 5:50 am

i heard some people talking to day about how much beefier some airbus structures are compared to Boeings

two particular areas mentioned were the rear pressure bulkhead, and the centre wing box!
 
widebodyphotog
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RE: Empty Weight Of 787-9 Vs A359. Whats Wrong!

Wed Apr 19, 2006 9:08 am

Quoting Lightsaber (Reply 14):
As the rest of the industy, a lighter airframe is worth more. About $500/kg.

Wow 'saber, that's a hell of a lot of dough...$11,500,000 between 777-200LR and A340-500...

Quoting Matt72033 (Reply 16):
i heard some people talking to day about how much beefier some airbus structures are compared to Boeings

two particular areas mentioned were the rear pressure bulkhead, and the centre wing box!

But what do you get for that? Increased cycle life? Sounds like a bit of over compensation considering there are no operational benefits from that "beefier" structure...I would be inclined to think that Airbus wing box structures have more heft, but what is the benefit of that?


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