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flipdewaf
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 12:38 pm

morrisond wrote:
tommy1808 wrote:
morrisond wrote:
Airbus structural engineers can't do magic vs Boeing Engineers if given the same materials budget to work with -.


:checkmark:
You are correct, Airbus engineers couldn´t add 7m of span without driving weight up quite a bit any more than Boeing engineers can.

best regards
Thomas


Yes there is no benefit of going from Aluminum to Carbon...It might have gone up a bit but 9T seems rather extreme.

Why? How much more do you think a wing that has 11% more span and 18% area should weigh?

Fred


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morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 12:42 pm

zeke wrote:
morrisond wrote:
According to the TCDS sheet the engines are 1.7T more and the nacelles are the same diameter.


My understanding is the nacelle diameter is 4.42 meters on the 779 and 3.96 m on the 77W. I doubt you found the nacelle information in the TCDS as it is normally not part of the engine, engines are tested without a nacelle.

morrisond wrote:
Look at Page 26 - it would seem to suggest that the structural weight has fallen by about 3,000 lbs since EIS - and the 2015/2016 changes increased payload ability by 5,000.


Your claim a few posts back was in 2016 that the OEW dropped 2%, that would be 7-7500lb, now you are saying a total of 3000lb since EIS, I think you should stop posting contradictory and misleading information. I went back and had a look at the Boeing presentations from 2016, and they said they were aiming for about 550 kg reduction. On an aircraft the size of the 77W it is very common for aircraft to have a few hundred kg difference in weight even if they were built right after each other.

Chaostheory wrote:
A cabin in a 772/359 size aircraft can be 10t of fixtures and fittings. I would expect any freighter based directly on the 359 to be 125t ish empty - perhaps a little lower. At most 135t for stretched variant with the -1000s MLG..


Our 359s have a MEW just under 120 tonnes, with about 15 tonnes for the cabin fit out. Back when the A350 was launched, Airbus was aiming at a 90t payload for the A359F essentially a MD11F replacement for volume and payload.

https://www.flightglobal.com/airbus-a35 ... 81.article

morrisond wrote:
That's the big issue for an Airbus launch decision - who would buy it? We know efficiency which is the 350's strength is not the number one issue for Freighters - Capital cost and capability are usually the bigger selling points.

That is a problem when cheap very capable end of line 77F are available for another 6 years and it's not like Boeing is capacity limited on the 777 production line - you can get one whenever you want. Boeing would probably cut you a pretty keen deal to keep the line humming.


The future of the 77F is really at the mercy of airports, as more restrictive noise measures are brought in the 77F as well as most other production or converted freighters flying today will not be allowed to operate at night.


Yes you are right on the nacelle - I was remembering something about them not wanting to increase the fan size much from the Ge90-115 to fit within the existing nacelle.

Please stop with the personal attacks - I am not deliberating posting misleading information. The problem is the media reports are often contradictory and not really clear what they are talking about.

I can't see where I said a 2% weight loss - I can see where I wrote 2T - which was based on that video I posted plus the weight loss in the crown that is either 1,800 lbs by itself or that also includes the tail skid deletion where I also found two numbers. I know Boeing talked about the 77W being 2% better overall due to weight loss, Aero Changes and a small PIP I believe.

Since EIS the airframe lost 3,000 lbs but there have been many changes elsewhere - insulation, tires, coatings - cabin changes - they all add up.

However nothing is really clear.

All I know for sure is in the ACAP it has a 2015 77W at 167,400 KG OEW. Which I said multiple times and the changes after may or may not be baked into that - which I said multiple times.
 
morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 12:48 pm

flipdewaf wrote:
morrisond wrote:
tommy1808 wrote:

:checkmark:
You are correct, Airbus engineers couldn´t add 7m of span without driving weight up quite a bit any more than Boeing engineers can.

best regards
Thomas


Yes there is no benefit of going from Aluminum to Carbon...It might have gone up a bit but 9T seems rather extreme.

Why? How much more do you think a wing that has 11% more span and 18% area should weigh?

Fred


Sent from my iPhone using Tapatalk


Hi Fred - The common belief on this website is that there were media reports that It gained no weight. Good luck in trying to find them - I have tried.

The better question is what do you have the Carbon A350 wing(s) weighing and the Aluminum 77W wing(s) weighing?
 
flipdewaf
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 1:40 pm

morrisond wrote:
flipdewaf wrote:
morrisond wrote:

Yes there is no benefit of going from Aluminum to Carbon...It might have gone up a bit but 9T seems rather extreme.

Why? How much more do you think a wing that has 11% more span and 18% area should weigh?

Fred


Sent from my iPhone using Tapatalk


Hi Fred - The common belief on this website is that there were media reports that It gained no weight. Good luck in trying to find them - I have tried.

The better question is what do you have the Carbon A350 wing(s) weighing and the Aluminum 77W wing(s) weighing?

43.6 for the A35k and 46.7 for the 77w.
779x is 55.7

Fred


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zeke
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 2:14 pm

morrisond wrote:
I can't see where I said a 2% weight loss - I can see where I wrote 2T - which was based on that video I posted plus the weight loss in the crown that is either 1,800 lbs by itself or that also includes the tail skid deletion where I also found two numbers. I know Boeing talked about the 77W being 2% better overall due to weight loss, Aero Changes and a small PIP I believe.


Post 434 you clearly stated a 2% weight drop and a PIP,

morrisond wrote:
So 30 early in the program and 20 from 2010-2015?

That's what I said - you don't seem to have frames from after 2015 when they lost weight due to a number of changes that apparently dropped the weight by about 2% and had aero improvements and PIP's.

You seem to have multiple 77W versions on property some with quite high density. Which ones are 169T and what year are they from?


I then went away and looked at a different airline that had later builds, and they dont have any significant weight change. As for the 2015 ACAPS you refer to, can you tell us the passenger numbers in the LOPA, is it 9 across or 10 across (365) ?

morrisond wrote:
The better question is what do you have the Carbon A350 wing(s) weighing and the Aluminum 77W wing(s) weighing?


Wings are primary structures that contain a whole host of systems, unless you understand the differences in flight control systems, high lift devices, electric systems, hydraulic systems, engine integration, and gear integration and how different they are between the two aircraft you will not understand where the hidden weight inside the wing is.

morrisond wrote:
The common belief on this website is that there were media reports that It gained no weight. Good luck in trying to find them - I have tried.


According to this article the 779 has lost about 5.4 tonnes during development https://medium.com/o530-carris-pt-heral ... 0dd601a83t

flipdewaf wrote:
43.6 for the A35k and 46.7 for the 77w.
779x is 55.7


Apparently on the Boeing tour they are told the "Wing body crane move to ACC 131 (heaviest move by crane)" and that section is 48 tonnes without all of the extra attachments like control surfaces, high lift devices etc. from https://courses.washington.edu/ie337/Bo ... 0Facts.pdf
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flipdewaf
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 2:18 pm

zeke wrote:

flipdewaf wrote:
43.6 for the A35k and 46.7 for the 77w.
779x is 55.7


Apparently on the Boeing tour they are told the "Wing body crane move to ACC 131 (heaviest move by crane)" and that section is 48 tonnes without all of the extra attachments like control surfaces, high lift devices etc. from https://courses.washington.edu/ie337/Bo ... 0Facts.pdf


My method has the controls separate for the rest of the wing so is the same (similar) as what you suggest.

Fred


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morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 2:37 pm

flipdewaf wrote:
morrisond wrote:
flipdewaf wrote:
Why? How much more do you think a wing that has 11% more span and 18% area should weigh?

Fred


Sent from my iPhone using Tapatalk


Hi Fred - The common belief on this website is that there were media reports that It gained no weight. Good luck in trying to find them - I have tried.

The better question is what do you have the Carbon A350 wing(s) weighing and the Aluminum 77W wing(s) weighing?

43.6 for the A35k and 46.7 for the 77w.
779x is 55.7

Fred


Sent from my iPad using Tapatalk


So you are assuming about 5T more than by interpolation based on the A35K wing weight of an older design?

Yes MTOW is higher by 10% ( no idea what the A350 or 777X wings are good for). Given Airbus greater tendency to bump MTOW over time I would not be surprised if they are designed for an ultimate MTOW surprisingly close.

Fuel capacity was increased by 320,863 to 350,410 lb (145,541 to 158,943 kg) - which I assume decreases the bending moment.

I think the sweep was decreased as well and aspect ratio went from 9:1 to 10:1. Plus then the extra weight of the tips.

But then it has to carry 2-3T more weight in the engines.

BTW - Why does Boeing call the 777X wing a 4th Gen Carbon Design? I know of the 787 - but what were 1 and 2? Or are they talking industry 4th Generation?

The other way to look at it is how does the A351 weigh so much less than the similar sized 77W - when the wings and engines of the 350 are only 5T less.

By some estimates the 350 saves another 15T on top of that with similar seating. If the engines and Wing are 61.6T (Wings 43.6 and Engines and about another 18T including nacelles and accessories) and the MEW weight is about 129T you are saving 15T tons on the remaining 67.4T or about 22.2%.

That seems pretty extreme when the weight savings on the wing is only about 6.4%.

It would make more sense that the 350 wing is lighter than 43.6T (greater than a 3T difference) and maybe the delta between the 77W and 77X is maybe not 9T.
Last edited by morrisond on Wed May 05, 2021 3:06 pm, edited 1 time in total.
 
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 3:02 pm

Polot wrote:
JayinKitsap wrote:
FedEx could be interested.

I imagine FedEx would rather wait and see how the 77Wp2F shakes out and performs. If it meets specs it would be very attractive to them, and fit in perfectly with their large 777F fleet.

That makes sense to me. They could continue to use 777F in the role they now do, long inter-continental hub to hub flights, and use 77WF in the role MD-11s now fill, shorter intra-continental hops. As Zeke points out A350F is sized for MD-11 replacement, but the issue becomes cost. MD-11s were mostly bought cheap and second hand, A350F would be factory new and anything but cheap. Time will tell...
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morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 3:04 pm

zeke wrote:
morrisond wrote:
I can't see where I said a 2% weight loss - I can see where I wrote 2T - which was based on that video I posted plus the weight loss in the crown that is either 1,800 lbs by itself or that also includes the tail skid deletion where I also found two numbers. I know Boeing talked about the 77W being 2% better overall due to weight loss, Aero Changes and a small PIP I believe.


Post 434 you clearly stated a 2% weight drop and a PIP,

morrisond wrote:
So 30 early in the program and 20 from 2010-2015?

That's what I said - you don't seem to have frames from after 2015 when they lost weight due to a number of changes that apparently dropped the weight by about 2% and had aero improvements and PIP's.

You seem to have multiple 77W versions on property some with quite high density. Which ones are 169T and what year are they from?


I then went away and looked at a different airline that had later builds, and they dont have any significant weight change. As for the 2015 ACAPS you refer to, can you tell us the passenger numbers in the LOPA, is it 9 across or 10 across (365) ?

morrisond wrote:
The better question is what do you have the Carbon A350 wing(s) weighing and the Aluminum 77W wing(s) weighing?


Wings are primary structures that contain a whole host of systems, unless you understand the differences in flight control systems, high lift devices, electric systems, hydraulic systems, engine integration, and gear integration and how different they are between the two aircraft you will not understand where the hidden weight inside the wing is.

morrisond wrote:
The common belief on this website is that there were media reports that It gained no weight. Good luck in trying to find them - I have tried.


According to this article the 779 has lost about 5.4 tonnes during development https://medium.com/o530-carris-pt-heral ... 0dd601a83t

flipdewaf wrote:
43.6 for the A35k and 46.7 for the 77w.
779x is 55.7


Apparently on the Boeing tour they are told the "Wing body crane move to ACC 131 (heaviest move by crane)" and that section is 48 tonnes without all of the extra attachments like control surfaces, high lift devices etc. from https://courses.washington.edu/ie337/Bo ... 0Facts.pdf


They lift both wings at once? That would be surprising.

Oops - yes I did type that 2% number - I corrected it later stating 2T but I believe I meant 2T from your 169T to the ACAP. I think an article I was reading said 2% improvement and they were talking about weight - it turns out the 2% was overall gain.

I guess it would have helped If I posted that article as well - I forgot the link last time - see page 26. It talks about another 1,200 in structure weight - Crown tie rods plus lighter insulation, plus lighter hydro fluid plus tail skid deletion (unless that is considered part of structure) - then from The Boeing video I posted - lighter tires, savings on coatings, savings on washers and fasteners. It's hard to know what is included in what number but it did go on a diet.

http://docshare04.docshare.tips/files/2 ... 607191.pdf
 
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 3:07 pm

morrisond wrote:
I guess it would have helped If I posted that article as well - I forgot the link last time - see page 26. It talks about another 1,200 in structure weight - Crown tie rods plus lighter insulation, plus lighter hydro fluid plus tail skid deletion (unless that is considered part of structure) - then from The Boeing video I posted - lighter tires, savings on coatings, savings on washers and fasteners. It's hard to know what is included in what number but it did go on a diet.

http://docshare04.docshare.tips/files/2 ... 607191.pdf

Hopefully they didn't chose to save on ground straps...

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tommy1808
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 3:08 pm

morrisond wrote:
flipdewaf wrote:
morrisond wrote:

Hi Fred - The common belief on this website is that there were media reports that It gained no weight. Good luck in trying to find them - I have tried.

The better question is what do you have the Carbon A350 wing(s) weighing and the Aluminum 77W wing(s) weighing?

43.6 for the A35k and 46.7 for the 77w.
779x is 55.7

Fred


Sent from my iPad using Tapatalk


The other way to look at it is how does the A351 weigh so much less than the similar sized 77W - when the wings and engines of the 350 are only 5T less.


55.7 - 43.6 is 12.1t, wee bit more than 5t.
Makes sense given it is 20% bigger, holds 10% more weight in the middle and is some 12% longer with the associated longer leverage for forces.

Given Airbus greater tendency to bump MTOW over time I would not be surprised if they are surprisingly close.


It already had an 11t bump. Airbus also doesn't really have a tendency to go wild on MTOW bumps. The A333 may create that impression, but that is a wing made for a 275t TOW aircraft right from the start.

Fuel capacity was increased by 320,863 to 350,410 lb (145,541 to 158,943 kg) - which I assume decreases the bending moment.


Fuel has a tendency to be used while flying. Good for average strain, irrelevant to the forces the wing has to withstand and hence its weight.

Best regards
Thomas
Well, there is prophecy in the bible after all: 2 Timothy 3:1-6
 
morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 3:11 pm

zeke wrote:
morrisond wrote:
I can't see where I said a 2% weight loss - I can see where I wrote 2T - which was based on that video I posted plus the weight loss in the crown that is either 1,800 lbs by itself or that also includes the tail skid deletion where I also found two numbers. I know Boeing talked about the 77W being 2% better overall due to weight loss, Aero Changes and a small PIP I believe.


Post 434 you clearly stated a 2% weight drop and a PIP,

morrisond wrote:
So 30 early in the program and 20 from 2010-2015?

That's what I said - you don't seem to have frames from after 2015 when they lost weight due to a number of changes that apparently dropped the weight by about 2% and had aero improvements and PIP's.

You seem to have multiple 77W versions on property some with quite high density. Which ones are 169T and what year are they from?


I then went away and looked at a different airline that had later builds, and they dont have any significant weight change. As for the 2015 ACAPS you refer to, can you tell us the passenger numbers in the LOPA, is it 9 across or 10 across (365) ?

morrisond wrote:
The better question is what do you have the Carbon A350 wing(s) weighing and the Aluminum 77W wing(s) weighing?


Wings are primary structures that contain a whole host of systems, unless you understand the differences in flight control systems, high lift devices, electric systems, hydraulic systems, engine integration, and gear integration and how different they are between the two aircraft you will not understand where the hidden weight inside the wing is.

morrisond wrote:
The common belief on this website is that there were media reports that It gained no weight. Good luck in trying to find them - I have tried.


According to this article the 779 has lost about 5.4 tonnes during development https://medium.com/o530-carris-pt-heral ... 0dd601a83t

flipdewaf wrote:
43.6 for the A35k and 46.7 for the 77w.
779x is 55.7


Apparently on the Boeing tour they are told the "Wing body crane move to ACC 131 (heaviest move by crane)" and that section is 48 tonnes without all of the extra attachments like control surfaces, high lift devices etc. from https://courses.washington.edu/ie337/Bo ... 0Facts.pdf


Hi Zeke - that link to the Medium article does not work or do you need a Subscription?

I think that Crane number is referring to something else. I doubt they would lift both wings at once - that must be the complete fuselage with wingbox which would probably be about that weight.

Maybe It's a Wing/Body crane in that it could lift a wing or a body.
 
morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 3:17 pm

tommy1808 wrote:
morrisond wrote:
flipdewaf wrote:
43.6 for the A35k and 46.7 for the 77w.
779x is 55.7

Fred


Sent from my iPad using Tapatalk


The other way to look at it is how does the A351 weigh so much less than the similar sized 77W - when the wings and engines of the 350 are only 5T less.


55.7 - 43.6 is 12.1t, wee bit more than 5t.
Makes sense given it is 20% bigger, holds 10% more weight in the middle and is some 12% longer with the associated longer leverage for forces.

Given Airbus greater tendency to bump MTOW over time I would not be surprised if they are surprisingly close.


It already had an 11t bump. Airbus also doesn't really have a tendency to go wild on MTOW bumps. The A333 may create that impression, but that is a wing made for a 275t TOW aircraft right from the start.

Fuel capacity was increased by 320,863 to 350,410 lb (145,541 to 158,943 kg) - which I assume decreases the bending moment.


Fuel has a tendency to be used while flying. Good for average strain, irrelevant to the forces the wing has to withstand and hence its weight.

Best regards
Thomas


By interprolation if you take the 350 wing weight and scale it up by 20% - the 777x wing should only be 5T more than 77W wing not 9T. Both 350 and 77X wings are made from Carbon and the 777x wing is 4th Generation - whatever that means. But it is newer than the 350 wing and an evolution of the 787 design.

From what I understand - in general you burn off the fuel in the center tank first lessening the bending moment on the wings. The fuel in the wings resists the forces of lift trying to snap it in half.

By the time you burn off all the fuel in the center tank and then the wing tanks the aircraft is significantly lighter and the wings can then withstand the forces inflicted on them without snapping.
 
morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 3:34 pm

tommy1808 wrote:
morrisond wrote:
flipdewaf wrote:
43.6 for the A35k and 46.7 for the 77w.
779x is 55.7

Fred


Sent from my iPad using Tapatalk


The other way to look at it is how does the A351 weigh so much less than the similar sized 77W - when the wings and engines of the 350 are only 5T less.


55.7 - 43.6 is 12.1t, wee bit more than 5t.
Makes sense given it is 20% bigger, holds 10% more weight in the middle and is some 12% longer with the associated longer leverage for forces.

Given Airbus greater tendency to bump MTOW over time I would not be surprised if they are surprisingly close.


It already had an 11t bump. Airbus also doesn't really have a tendency to go wild on MTOW bumps. The A333 may create that impression, but that is a wing made for a 275t TOW aircraft right from the start.

Fuel capacity was increased by 320,863 to 350,410 lb (145,541 to 158,943 kg) - which I assume decreases the bending moment.


Fuel has a tendency to be used while flying. Good for average strain, irrelevant to the forces the wing has to withstand and hence its weight.

Best regards
Thomas


Airbus doesn't tend to go wild on MTOW bumps? I think the 321 has grown by 21% from 83T on the A321-100 to 101T on the XLR.

The A350 wing is larger and has the same span as the 77W - and MTOW's higher than 319T were rumoured when the potential 1100 and 1200 variants were being floated around. You would figure it can take more than 319T or that would have been pretty poor planning.

Airbus tends to figure out how to get more out of existing structure and bump MTOW while Boeing tends to try and remove weight and keep the same MTOW.
 
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 4:02 pm

morrisond wrote:
Hi Zeke - that link to the Medium article does not work or do you need a Subscription?


No subscription required, try https://link.medium.com/vZ7kyLzZ0fb or https://medium.com/o530-carris-pt-heral ... 80dd601a83 or put the keywords “medium 777 190,000” should give the article.

morrisond wrote:
I think that Crane number is referring to something else. I doubt they would lift both wings at once - that must be the complete fuselage with wingbox which would probably be about that weight.


Boeing join both wings to the centre section and then lift the whole assembly into the FAL as one piece.
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zeke
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 4:12 pm

morrisond wrote:
From what I understand - in general you burn off the fuel in the center tank first lessening the bending moment on the wings. The fuel in the wings resists the forces of lift trying to snap it in half.

By the time you burn off all the fuel in the center tank and then the wing tanks the aircraft is significantly lighter and the wings can then withstand the forces inflicted on them without snapping.


Going back a few posts I said you need to understand the systems to understand the wing, the A350 wing is variable camber which means the wing section is actively modified in flight to reduce wing loading and drag. There is nothing comparable to that on the 77W, one cannot really draw direct comparisons.
“Don't be a show-off. Never be too proud to turn back. There are old pilots and bold pilots, but no old, bold pilots.” E. Hamilton Lee, 1949
 
flipdewaf
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 5:07 pm

morrisond wrote:
tommy1808 wrote:
morrisond wrote:

The other way to look at it is how does the A351 weigh so much less than the similar sized 77W - when the wings and engines of the 350 are only 5T less.


55.7 - 43.6 is 12.1t, wee bit more than 5t.
Makes sense given it is 20% bigger, holds 10% more weight in the middle and is some 12% longer with the associated longer leverage for forces.

Given Airbus greater tendency to bump MTOW over time I would not be surprised if they are surprisingly close.


It already had an 11t bump. Airbus also doesn't really have a tendency to go wild on MTOW bumps. The A333 may create that impression, but that is a wing made for a 275t TOW aircraft right from the start.

Fuel capacity was increased by 320,863 to 350,410 lb (145,541 to 158,943 kg) - which I assume decreases the bending moment.


Fuel has a tendency to be used while flying. Good for average strain, irrelevant to the forces the wing has to withstand and hence its weight.

Best regards
Thomas


By interprolation if you take the 350 wing weight and scale it up by 20% - the 777x wing should only be 5T more than 77W wing not 9T. Both 350 and 77X wings are made from Carbon and the 777x wing is 4th Generation - whatever that means. But it is newer than the 350 wing and an evolution of the 787 design.

From what I understand - in general you burn off the fuel in the center tank first lessening the bending moment on the wings. The fuel in the wings resists the forces of lift trying to snap it in half.

By the time you burn off all the fuel in the center tank and then the wing tanks the aircraft is significantly lighter and the wings can then withstand the forces inflicted on them without snapping.


Your interpretation of burning off fuel is basically correct. The limit load case is generally MZFW.
Why would you interpolate like that? It doesn’t scale that way. The max bending moment broadly scales at wL^2/thickness. The material required then scales at wL^3/thickness. (There’s more to it than that but that accounts for most of it).

Fred


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morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 5:18 pm

zeke wrote:
morrisond wrote:
From what I understand - in general you burn off the fuel in the center tank first lessening the bending moment on the wings. The fuel in the wings resists the forces of lift trying to snap it in half.

By the time you burn off all the fuel in the center tank and then the wing tanks the aircraft is significantly lighter and the wings can then withstand the forces inflicted on them without snapping.


Going back a few posts I said you need to understand the systems to understand the wing, the A350 wing is variable camber which means the wing section is actively modified in flight to reduce wing loading and drag. There is nothing comparable to that on the 77W, one cannot really draw direct comparisons.


How does anything you wrote have anything to do with what I wrote? Mine was a reponse to something entirely different.

But it seems like Boeing has been able to change the camber as well since 2009 on the 300ER and it was back ported to the first gen 777's as well - I think the 787 has the same ability.

https://www.boeing.com/commercial/aerom ... _02_1.html

Is Medium any better than WIKI? They also state in the article that the 77X should be able to carry many tons more than the A351 which if they are right on the OEW weight even at 184T with MZFW of 255T (71T of lift) can't really be true can it based on what you have seen the A351 can lift (about 75T to MZFW)?
 
morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 5:28 pm

flipdewaf wrote:
morrisond wrote:
tommy1808 wrote:

55.7 - 43.6 is 12.1t, wee bit more than 5t.
Makes sense given it is 20% bigger, holds 10% more weight in the middle and is some 12% longer with the associated longer leverage for forces.



It already had an 11t bump. Airbus also doesn't really have a tendency to go wild on MTOW bumps. The A333 may create that impression, but that is a wing made for a 275t TOW aircraft right from the start.



Fuel has a tendency to be used while flying. Good for average strain, irrelevant to the forces the wing has to withstand and hence its weight.

Best regards
Thomas


By interprolation if you take the 350 wing weight and scale it up by 20% - the 777x wing should only be 5T more than 77W wing not 9T. Both 350 and 77X wings are made from Carbon and the 777x wing is 4th Generation - whatever that means. But it is newer than the 350 wing and an evolution of the 787 design.

From what I understand - in general you burn off the fuel in the center tank first lessening the bending moment on the wings. The fuel in the wings resists the forces of lift trying to snap it in half.

By the time you burn off all the fuel in the center tank and then the wing tanks the aircraft is significantly lighter and the wings can then withstand the forces inflicted on them without snapping.


Your interpretation of burning off fuel is basically correct. The limit load case is generally MZFW.
Why would you interpolate like that? It doesn’t scale that way. The max bending moment broadly scales at wL^2/thickness. The material required then scales at wL^3/thickness. (There’s more to it than that but that accounts for most of it).

Fred


Sent from my iPad using Tapatalk


I was just estimating taking weight increase proportional to size increase. Take a look at my other post where it seems like Airbus is only shaving 6.4% off wing weight on A350 and 22% on the rest of the structure.

Does that make any sense at all?
 
mjoelnir
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 5:37 pm

morrisond wrote:
flipdewaf wrote:
morrisond wrote:

By interprolation if you take the 350 wing weight and scale it up by 20% - the 777x wing should only be 5T more than 77W wing not 9T. Both 350 and 77X wings are made from Carbon and the 777x wing is 4th Generation - whatever that means. But it is newer than the 350 wing and an evolution of the 787 design.

From what I understand - in general you burn off the fuel in the center tank first lessening the bending moment on the wings. The fuel in the wings resists the forces of lift trying to snap it in half.

By the time you burn off all the fuel in the center tank and then the wing tanks the aircraft is significantly lighter and the wings can then withstand the forces inflicted on them without snapping.


Your interpretation of burning off fuel is basically correct. The limit load case is generally MZFW.
Why would you interpolate like that? It doesn’t scale that way. The max bending moment broadly scales at wL^2/thickness. The material required then scales at wL^3/thickness. (There’s more to it than that but that accounts for most of it).

Fred


Sent from my iPad using Tapatalk


I was just estimating taking weight increase proportional to size increase. Take a look at my other post where it seems like Airbus is only shaving 6.4% off wing weight on A350 and 22% on the rest of the structure.

Does that make any sense at all?


Shaving weight compared to what? The 777X can be compared to the 777, but to what are you trying to compare the A350?
 
WIederling
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 5:44 pm

morrisond wrote:
I was just estimating taking weight increase proportional to size increase. Take a look at my other post where it seems like Airbus is only shaving 6.4% off wing weight on A350 and 22% on the rest of the structure.

Does that make any sense at all?


linear scaling by 10% increases volume by 33% ( 1.1 ** 3 )
( reason why the A380 had less span than would be expected by simplistic scaling assumptions.
with a comparable aspect ratio to the A330/A350 wings weight would have grown over all bounds)
Murphy is an optimist
 
morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 6:19 pm

mjoelnir wrote:
morrisond wrote:
flipdewaf wrote:

Your interpretation of burning off fuel is basically correct. The limit load case is generally MZFW.
Why would you interpolate like that? It doesn’t scale that way. The max bending moment broadly scales at wL^2/thickness. The material required then scales at wL^3/thickness. (There’s more to it than that but that accounts for most of it).

Fred


Sent from my iPad using Tapatalk


I was just estimating taking weight increase proportional to size increase. Take a look at my other post where it seems like Airbus is only shaving 6.4% off wing weight on A350 and 22% on the rest of the structure.

Does that make any sense at all?


Shaving weight compared to what? The 777X can be compared to the 777, but to what are you trying to compare the A350?


We are talking about modern large carbon wings - trying to estimate the weight of the 777X wing vs the 77W which is hard to do as they are not the same materials and people keep saying the 777X wing did not gain any weight - but no one can find sources.
Last edited by morrisond on Wed May 05, 2021 6:23 pm, edited 1 time in total.
 
morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 6:22 pm

WIederling wrote:
morrisond wrote:
I was just estimating taking weight increase proportional to size increase. Take a look at my other post where it seems like Airbus is only shaving 6.4% off wing weight on A350 and 22% on the rest of the structure.

Does that make any sense at all?


linear scaling by 10% increases volume by 33% ( 1.1 ** 3 )
( reason why the A380 had less span than would be expected by simplistic scaling assumptions.
with a comparable aspect ratio to the A330/A350 wings weight would have grown over all bounds)


Luckily the 777X increased the aspect ratio from 9:1 to 10:1 then.

I know simplistic scaling doesn't work - I didn't say it did. Basically my suggestion is that the A350 wing might be lighter than what Fred's model is showing - as in it's better - which as its carbon could make his estimate on 777X high.
 
mjoelnir
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 6:37 pm

morrisond wrote:
mjoelnir wrote:
morrisond wrote:

I was just estimating taking weight increase proportional to size increase. Take a look at my other post where it seems like Airbus is only shaving 6.4% off wing weight on A350 and 22% on the rest of the structure.

Does that make any sense at all?


Shaving weight compared to what? The 777X can be compared to the 777, but to what are you trying to compare the A350?


We are talking about modern large carbon wings - trying to estimate the weight of the 777X wing vs the 77W which is hard to do as they are not the same materials and people keep saying the 777X wing did not gain any weight - but no one can find sources.


Again to what you are trying to compare the A350 when you talk about 22%?

I regards to modern large carbon wings, how much weight does the folding wing add?
Boeing is very good with catch phrases like fourth generation wing. I myself see no indication for the 777X wing being more efficient than the A360 wing, rather the other way round.

I think Boeing did trust to much on the engines to pull them out. Miracles do not happen always, like with the 777-300ER. I think the difference between the GE9X and the Trent XWB will be to small to give the 777X an advantage.
 
Opus99
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 6:48 pm

mjoelnir wrote:
morrisond wrote:
mjoelnir wrote:

Shaving weight compared to what? The 777X can be compared to the 777, but to what are you trying to compare the A350?


We are talking about modern large carbon wings - trying to estimate the weight of the 777X wing vs the 77W which is hard to do as they are not the same materials and people keep saying the 777X wing did not gain any weight - but no one can find sources.


Again to what you are trying to compare the A350 when you talk about 22%?

I regards to modern large carbon wings, how much weight does the folding wing add?
Boeing is very good with catch phrases like fourth generation wing. I myself see no indication for the 777X wing being more efficient than the A360 wing, rather the other way round.

I think Boeing did trust to much on the engines to pull them out. Miracles do not happen always, like with the 777-300ER. I think the difference between the GE9X and the Trent XWB will be to small to give the 777X an advantage.

Some who have seen the data from GE9X might disagree with you I.e. lightsaber. If you have data to counter please do share
 
flipdewaf
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 8:02 pm

morrisond wrote:
WIederling wrote:
morrisond wrote:
I was just estimating taking weight increase proportional to size increase. Take a look at my other post where it seems like Airbus is only shaving 6.4% off wing weight on A350 and 22% on the rest of the structure.

Does that make any sense at all?


linear scaling by 10% increases volume by 33% ( 1.1 ** 3 )
( reason why the A380 had less span than would be expected by simplistic scaling assumptions.
with a comparable aspect ratio to the A330/A350 wings weight would have grown over all bounds)


Luckily the 777X increased the aspect ratio from 9:1 to 10:1 then.


High AR is a double whammy! Longer is worse for weight and looser chord means lower thickness means even heavier. If we take the WL^3/ thickness scaling parameter of two wings of identical area and give one a 10% higher AR then you get a quadruple whammy (nearly), not only are you increasing span but you are decreasing thickness (assumption of constant t/c).
morrisond wrote:

I know simplistic scaling doesn't work - I didn't say it did. Basically my suggestion is that the A350 wing might be lighter than what Fred's model is showing - as in it's better - which as its carbon could make his estimate on 777X high.


The A35k is saving weight in the fuselage (by being slightly smaller, that old chestnut) having a lower MTOW so needing a lighter propulsion system and having a slightly lower capacity so needing less cabin furnishings. It’s saves a bunch of weight in the gear by the same mechanism as the propulsion system. Smaller feathers also make for lighter aircraft.

Incidentally all those things that make an aircraft light and optimised for low fuel burn pax running don’t help nearly so much on the world of freight, the higher the specific range the bigger the range hit from adding freight capability to MZFW.

Fred


Sent from my iPad using Tapatalk
Image
 
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 10:45 pm

flipdewaf wrote:
morrisond wrote:
WIederling wrote:

linear scaling by 10% increases volume by 33% ( 1.1 ** 3 )
( reason why the A380 had less span than would be expected by simplistic scaling assumptions.
with a comparable aspect ratio to the A330/A350 wings weight would have grown over all bounds)


Luckily the 777X increased the aspect ratio from 9:1 to 10:1 then.


High AR is a double whammy! Longer is worse for weight and looser chord means lower thickness means even heavier. If we take the WL^3/ thickness scaling parameter of two wings of identical area and give one a 10% higher AR then you get a quadruple whammy (nearly), not only are you increasing span but you are decreasing thickness (assumption of constant t/c).
morrisond wrote:

I know simplistic scaling doesn't work - I didn't say it did. Basically my suggestion is that the A350 wing might be lighter than what Fred's model is showing - as in it's better - which as its carbon could make his estimate on 777X high.


The A35k is saving weight in the fuselage (by being slightly smaller, that old chestnut) having a lower MTOW so needing a lighter propulsion system and having a slightly lower capacity so needing less cabin furnishings. It’s saves a bunch of weight in the gear by the same mechanism as the propulsion system. Smaller feathers also make for lighter aircraft.

Incidentally all those things that make an aircraft light and optimised for low fuel burn pax running don’t help nearly so much on the world of freight, the higher the specific range the bigger the range hit from adding freight capability to MZFW.

Fred


Sent from my iPad using Tapatalk


Hi Fred - the A350 is marginally smaller than the 77W - you are talking 4" in Height and 8" width. The passenger Cabins and lengths of the A351 and 77W are nearly identical. You can cram 10W into an A351 - its been done.

I get that every little bit will be lighter.

What I am really wondering about is what I wrote about above given the OEW weight difference between A351 and 77W is about 20T

Quoting Myself

"The other way to look at it is how does the A351 weigh so much less than the similar sized 77W - when the wings and engines of the 350 are only about 5T less.

By some estimates the 350 saves another 15T on top of that with similar seating. If the engines and Wing are 61.6T (Wings 43.6 and Engines and about another 18T including nacelles and accessories) and the MEW weight is about 129T you are saving 15T tons on the remaining 67.4T or about 22.2%.

That seems pretty extreme when the weight savings on the wing is only about 6.4%.

It would make more sense that the 350 wing is lighter than 43.6T (greater than a 3T difference) and maybe the delta between the 77W and 77X is maybe not 9T."

I know the 350 wing is about 3% larger than the 77W. You are showing a weight loss of 6.4% on the wing - applying the 20T over the 129T MEW would be about 15.5%. So maybe 10-12% lighter due to the bigger size all things being equal. But they aren't equal as the 350 wing is Carbon vs Metal.

Take the 350 wing to an 15.5% weight loss and that is another 4T off it putting it under 40T and then the delta to what you are assuming on the 777Xf which would then be 13T would be pretty extreme.

I think the 777X wing will be heavier - but 5T vs 9T sounds more reasonable, which still has me assuming the 777X will be under 180T. 167T 77W + 3T Engines + 3T stretch + 5T wing less 2-4T less systems and interior weight - then some more for Bigger windows, stronger wingbox, heavier upper frames.
 
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zeke
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Re: A350F. Airbus looking to launch: Looking for customers

Wed May 05, 2021 11:36 pm

morrisond wrote:
How does anything you wrote have anything to do with what I wrote? Mine was a reponse to something entirely different.


Your comments on bending moments is fundamentally flawed as you do no understand the systems.

morrisond wrote:
But it seems like Boeing has been able to change the camber as well since 2009 on the 300ER and it was back ported to the first gen 777's as well


No drooped ailerons is not variable camber, all Airbus FBW have been using drooped ailerons for the past 30+ years for load alleviation and lift generation.

The A350 is able to move the lift distribution in flight, when its heavy the lift distribution is moved closer to the fuselage, when its lighter its moved away, this results in lower bending moments and a lighter wing.

morrisond wrote:
Is Medium any better than WIKI? They also state in the article that the 77X should be able to carry many tons more than the A351 which if they are right on the OEW weight even at 184T with MZFW of 255T (71T of lift) can't really be true can it based on what you have seen the A351 can lift (about 75T to MZFW)?


Medium is different from wiki as its original content where authors put their real name to it. Many articles I read also have github repositories where you can replicate and modify their work. The OEW he has used for the -1000 is too high, all of our -1000s are a few tonnes under 150 tonnes, so the real life numbers are around 7 tonnes better than his article.

When it comes to empty weights Boeing has given us a data points on where they see their nominal marketing payload and range, we also have their comments on the improvements relative to the 77W. If you try and claim the OEW for the 779 is around 170 tonnes, it means the fuel burn is 1 tonne an hour higher than it would be if the OEW was at 184 tonnes, because we know they marketing datapoint of marketing payload at marketing range takes off at MTOW.

In this table below I have done a quick demonstration of what the fuel burns would be if the A150-1000 OEW was 150 tonnes or 155 tonnes, and the 777-9 OEW was 170 tonnes or 184 tonnes, in both cases I have assumed that the aircraft land with OEW+ passengers+7000 kg of fuel and they takeoff at MTOW (which is what the marketing range is based upon).

If we look at the OEW of 155 tonnes for the A350-1000, the fuel burn is below what Airbus Flysmart calculates the fuel burn wll be for 8700 nm, where it is in close correlation with the 150 tonne OEW numbers. I know where I work all of our -1000s are below 150 tonnes.

For the 777-9 if you are saying the OEW is 170 tonnes, it means the fuel burn per hour must be adjusted higher, to a level higher than the 77W which is not reasonable, with a OEW of 184 tonnes, the fuel burn per hour is closer to the 77W which is what we expect for the 777-9.

https://i.ibb.co/n3hJTvg/779-OEW.jpg

Image
“Don't be a show-off. Never be too proud to turn back. There are old pilots and bold pilots, but no old, bold pilots.” E. Hamilton Lee, 1949
 
morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 12:51 am

zeke wrote:
morrisond wrote:
How does anything you wrote have anything to do with what I wrote? Mine was a reponse to something entirely different.


Your comments on bending moments is fundamentally flawed as you do no understand the systems.

morrisond wrote:
But it seems like Boeing has been able to change the camber as well since 2009 on the 300ER and it was back ported to the first gen 777's as well


No drooped ailerons is not variable camber, all Airbus FBW have been using drooped ailerons for the past 30+ years for load alleviation and lift generation.

The A350 is able to move the lift distribution in flight, when its heavy the lift distribution is moved closer to the fuselage, when its lighter its moved away, this results in lower bending moments and a lighter wing.

morrisond wrote:
Is Medium any better than WIKI? They also state in the article that the 77X should be able to carry many tons more than the A351 which if they are right on the OEW weight even at 184T with MZFW of 255T (71T of lift) can't really be true can it based on what you have seen the A351 can lift (about 75T to MZFW)?


Medium is different from wiki as its original content where authors put their real name to it. Many articles I read also have github repositories where you can replicate and modify their work. The OEW he has used for the -1000 is too high, all of our -1000s are a few tonnes under 150 tonnes, so the real life numbers are around 7 tonnes better than his article.

When it comes to empty weights Boeing has given us a data points on where they see their nominal marketing payload and range, we also have their comments on the improvements relative to the 77W. If you try and claim the OEW for the 779 is around 170 tonnes, it means the fuel burn is 1 tonne an hour higher than it would be if the OEW was at 184 tonnes, because we know they marketing datapoint of marketing payload at marketing range takes off at MTOW.

In this table below I have done a quick demonstration of what the fuel burns would be if the A150-1000 OEW was 150 tonnes or 155 tonnes, and the 777-9 OEW was 170 tonnes or 184 tonnes, in both cases I have assumed that the aircraft land with OEW+ passengers+7000 kg of fuel and they takeoff at MTOW (which is what the marketing range is based upon).

If we look at the OEW of 155 tonnes for the A350-1000, the fuel burn is below what Airbus Flysmart calculates the fuel burn wll be for 8700 nm, where it is in close correlation with the 150 tonne OEW numbers. I know where I work all of our -1000s are below 150 tonnes.

For the 777-9 if you are saying the OEW is 170 tonnes, it means the fuel burn per hour must be adjusted higher, to a level higher than the 77W which is not reasonable, with a OEW of 184 tonnes, the fuel burn per hour is closer to the 77W which is what we expect for the 777-9.

https://i.ibb.co/n3hJTvg/779-OEW.jpg

Image


Zeke - as Fred stated my comments on bending moments were essentially right - you took that quote totally out of context.

Yes - I missed that the 77W system was working on the Aileron and not the flaps. However the 787 does have an active electronic variable camber system that works on the flaps. The 777X has that system as well.

My point still stands about the weight of the 350 wing. How is it only 6.4% less weight than an 77W wing when it has Variable Camber so it does not need to be as strong, only needs to lift 90% of the weight of the 77W and is made of carbon. The 77x has all that tech.

Either Airbus engineers suck at building light wings and are awesome at the rest of the aircraft (which I don't believe) - or the 350 wing is lighter and the 77x wing won't be nearly as heavy as assumed over the 77w wing.

I never said the 77x would be 170T - I've been saying mid to upper 170's.

I suspect Boeing's marketing material is wrong. Something doesn't make sense. They claim a fuel burn advantage on a per seat advantage of the 779 over the 359.

The Ge9x is quoted as being 10% better than the Ge90-115 and the new wing is good for 3-4%. The 779 has 12% more seats than the 351. If it is a little bit more efficient per seat (say 2%) fuel flow should be more like 7,300-7,400 lbs per hour.

They are probably sandbagging on a few things including range. Which is what I would do if I was afraid of an A351 with new engines that could EIS 4-5 years after the 77X makes its EIS, and why I suspect the 778 is also about dead as dodo as the 779 may end up being a lot more capable than expected.
 
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 1:56 am

Article talking about 777X wing https://aviationweek.com/aerospace/prog ... t-campaign

"The wing is Boeing’s fourth generation large composite design and incorporates a modified trailing edge variable camber system derived from the 787 as well as a maneuver load alleviation system to limit stresses on the wing and reduce structural weight."
 
tommy1808
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 3:15 am

morrisond wrote:
.They are probably sandbagging on a few things including range.


Even to their customers, losing project sunrise as a result?

Which is what I would do if I was afraid of an A351 with new engines that could EIS 4-5 years after the 77X makes its EIS, and why I suspect the 778 is also about dead as dodo as the 779 may end up being a lot more capable than expected.


Thing is, and Zeke made a good attempt at explaining it: if it's better than expected as a passenger yet, it becomes a worse basis for a cargo plane, and the other way round.
And a 779 a lot more capable than marketing materia would have been perfect for Qantas.

Best regards
Thomas
Well, there is prophecy in the bible after all: 2 Timothy 3:1-6
 
smartplane
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 4:18 am

morrisond wrote:
They are probably sandbagging on a few things including range. Which is what I would do if I was afraid of an A351 with new engines that could EIS 4-5 years after the 77X makes its EIS, and why I suspect the 778 is also about dead as dodo as the 779 may end up being a lot more capable than expected.

Sandbagging who?

Nothing is left 'under the table'. If there was great news, combined with a high level of confidence, it would be used to underpin real world performance guarantees and penalties, encouraging customers to convert conditional orders to unconditional.

That this hasn't / isn't happening suggests there is no good news. Neither is there bad news.

Sunrise gave Boeing an insight, at that time, into how much they needed to raise X and 787 performance, and the degree of Airbus confidence. Meantime, neither Boeing or Airbus will have been resting.
 
flipdewaf
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 7:49 am

morrisond wrote:
flipdewaf wrote:
morrisond wrote:

Luckily the 777X increased the aspect ratio from 9:1 to 10:1 then.


High AR is a double whammy! Longer is worse for weight and looser chord means lower thickness means even heavier. If we take the WL^3/ thickness scaling parameter of two wings of identical area and give one a 10% higher AR then you get a quadruple whammy (nearly), not only are you increasing span but you are decreasing thickness (assumption of constant t/c).
morrisond wrote:

I know simplistic scaling doesn't work - I didn't say it did. Basically my suggestion is that the A350 wing might be lighter than what Fred's model is showing - as in it's better - which as its carbon could make his estimate on 777X high.


The A35k is saving weight in the fuselage (by being slightly smaller, that old chestnut) having a lower MTOW so needing a lighter propulsion system and having a slightly lower capacity so needing less cabin furnishings. It’s saves a bunch of weight in the gear by the same mechanism as the propulsion system. Smaller feathers also make for lighter aircraft.

Incidentally all those things that make an aircraft light and optimised for low fuel burn pax running don’t help nearly so much on the world of freight, the higher the specific range the bigger the range hit from adding freight capability to MZFW.

Fred


Sent from my iPad using Tapatalk


Hi Fred - the A350 is marginally smaller than the 77W - you are talking 4" in Height and 8" width. The passenger Cabins and lengths of the A351 and 77W are nearly identical. You can cram 10W into an A351 - its been done.


There’s ~2t difference between them, I know you like to ignore fuselage weight but it’s there.
morrisond wrote:

I get that every little bit will be lighter.

What I am really wondering about is what I wrote about above given the OEW weight difference between A351 and 77W is about 20T

Quoting Myself

"The other way to look at it is how does the A351 weigh so much less than the similar sized 77W - when the wings and engines of the 350 are only about 5T less.

The propulsion system itself is about 5t different.
morrisond wrote:

By some estimates the 350 saves another 15T on top of that with similar seating. If the engines and Wing are 61.6T (Wings 43.6 and Engines and about another 18T including nacelles and accessories) and the MEW weight is about 129T you are saving 15T tons on the remaining 67.4T or about 22.2%.

That seems pretty extreme when the weight savings on the wing is only about 6.4%.

A similar spanned (although larger in area) wing that has to lift 6.4% less in the limit case has remarkably 6.4% lower weight? Hardly surprising for a structure that’s already highly optimised. We also need to remember that the A35k has a lower t/c than it’s sister aircraft.
morrisond wrote:

It would make more sense that the 350 wing is lighter than 43.6T (greater than a 3T difference) and maybe the delta between the 77W and 77X is maybe not 9T."


Would make more sense or fit your narrative better?
morrisond wrote:

I know the 350 wing is about 3% larger than the 77W. You are showing a weight loss of 6.4% on the wing - applying the 20T over the 129T MEW would be about 15.5%. So maybe 10-12% lighter due to the bigger size all things being equal. But they aren't equal as the 350 wing is Carbon vs Metal.

Maybe carbon isn’t the panacea you suggest? I mean look at the monumental weight savings the B787 made over the A330... especially when you consider the huge weight savings the 787 systems bring...
morrisond wrote:

Take the 350 wing to an 15.5% weight loss and that is another 4T off it putting it under 40T and then the delta to what you are assuming on the 777Xf which would then be 13T would be pretty extreme.


Or let’s just not pull stuff out of thin air and notice that a 184t 779x with associated aero we would expect from its configuration and SFC expected from a very good GE9x would give the range as stated by Boeing. Occasionally razor, the explanation with fewest assumptions is usually correct.
morrisond wrote:

I think the 777X wing will be heavier - but 5T vs 9T sounds more reasonable,

Based on what?
morrisond wrote:

which still has me assuming the 777X will be under 180T. 167T 77W + 3T Engines + 3T stretch + 5T wing less 2-4T less systems and interior weight - then some more for Bigger windows, stronger wingbox, heavier upper frames.

Are you trying to say that the wing box isn’t the wing? Yeah, now it makes sense. The wing is 5t heavier but the wing box is 4t heavier. We agree.

What is the 2-4t less “systems”? What are the “systems”? I mean to think it will be 2-4t less I guess you have an estimate of what it actually weighs? Are the 77W system currently ~6t of your weight estimate? Or are they 15t?

Fred


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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 8:00 am

morrisond wrote:
Polot wrote:
JayinKitsap wrote:
FedEx could be interested.

I imagine FedEx would rather wait and see how the 77Wp2F shakes out and performs. If it meets specs it would be very attractive to them, and fit in perfectly with their large 777F fleet.


That's the big issue for an Airbus launch decision - who would buy it? We know efficiency which is the 350's strength is not the number one issue for Freighters - Capital cost and capability are usually the bigger selling points.

That is a problem when cheap very capable end of line 77F are available for another 6 years and it's not like Boeing is capacity limited on the 777 production line - you can get one whenever you want. Boeing would probably cut you a pretty keen deal to keep the line humming.
...
So maybe the better question is - what does the big freighter replacement market look like at the end of this decade? What will need to be replaced then?


I think it is in Boeing's best interest to support the 77Wp2f, and possibly develop their own design. Any loss in new build sales will be partially made up by more passenger plane interest as those with 77W's have a better trade in deal. The capabilities of the 77Wp2f are enough different than a 77F or the proposed 77xF to compete no more than any other conversion.

The best case for Boeing is the 764xF proposed, new efficiency engines in a size between the existing freighters on the market. A great candidate for new builds that conversions can't touch.
 
FluidFlow
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 9:26 am

According to wikipedia (I know it is not a reliable source but it has easy access), the A339 gained 6.2% OEW over the A333, translated to the 777X that is 10.4t on additional OEW. Mind that the 6.2% include the engines and the Trent-7000 only gained 300kg dry weight over the Trent-700 (roughly 5%). The GE9X seems to be over 10% heavier than the previous GE engines on the 77W. That leads to more strengthening needed compared to the work that was needed on the 339. So Boeing will have a hard time to keep the OEW increase at 6.2%.

If Airbus managed an increase of 6.2% on engines that are 5% heavier with a slight stretch, Boeing will be very good if they can manage a 10% increase in OEW on 10% heavier engines.

10% increase of OEW on the 779 from the 77W would be around 183t, what seems to match the performance data from zeke.
Combined with the fact that Boeing has not been able to keep 779 orders and has a very hard time to sell more seems to indicate that the 779 will not beat expectations but is more or less hitting the targets set out at launch 2013 (one year before the 339). So the level of technological advances that was going into the two is similar. Boeing has about 5 years more time compared to the 339 to get things better but I do not see how they can reduce the OEW increase below 10% when the engines get so much heavier.
 
tommy1808
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 9:51 am

FluidFlow wrote:
According to wikipedia (I know it is not a reliable source but it has easy access), the A339 gained 6.2% OEW over the A333.


yeah, and that weight is not supported by the sources linked, but there is one user that always edits the A339 weight back up when it is corrected.

Hifly has registration specific files on its website and their A339 is only 2.140 Kg or ~1.5% heavier than their A333, while having 86 more installed seats....
https://hifly.aero/public/uploads/2019/ ... 9H-HFC.pdf
https://hifly.aero/public/uploads/2019/ ... -TKY-1.pdf

Airbus had the option to slim down a wing made for a 275t aircraft to support no more than 251t when making the Neo.

best regards
Thomas
Well, there is prophecy in the bible after all: 2 Timothy 3:1-6
 
FluidFlow
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 9:58 am

tommy1808 wrote:
FluidFlow wrote:
According to wikipedia (I know it is not a reliable source but it has easy access), the A339 gained 6.2% OEW over the A333.


yeah, and that weight is not supported by the sources linked, but there is one user that always edits the A339 weight back up when it is corrected.

Hifly has registration specific files on its website and their A339 is only 2.140 Kg or ~1.5% heavier than their A333, while having 86 more installed seats....
https://hifly.aero/public/uploads/2019/ ... 9H-HFC.pdf
https://hifly.aero/public/uploads/2019/ ... -TKY-1.pdf

Airbus had the option to slim down a wing made for a 275t aircraft to support no more than 251t when making the Neo.

best regards
Thomas


That are really interesting numbers thanks for the infos. So the wing on the A339 is "slimmed" down? Or did Airbus not opt for the weight loss? I did not know the old A333 wing was designed for 275t MTOW. That was very ambitious? Though it must have been coming from the A343.
 
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Polot
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 10:05 am

FluidFlow wrote:
tommy1808 wrote:
FluidFlow wrote:
According to wikipedia (I know it is not a reliable source but it has easy access), the A339 gained 6.2% OEW over the A333.


yeah, and that weight is not supported by the sources linked, but there is one user that always edits the A339 weight back up when it is corrected.

Hifly has registration specific files on its website and their A339 is only 2.140 Kg or ~1.5% heavier than their A333, while having 86 more installed seats....
https://hifly.aero/public/uploads/2019/ ... 9H-HFC.pdf
https://hifly.aero/public/uploads/2019/ ... -TKY-1.pdf

Airbus had the option to slim down a wing made for a 275t aircraft to support no more than 251t when making the Neo.

best regards
Thomas


That are really interesting numbers thanks for the infos. So the wing on the A339 is "slimmed" down? Or did Airbus not opt for the weight loss? I did not know the old A333 wing was designed for 275t MTOW. That was very ambitious? Though it must have been coming from the A343.

It’s coming from the A343. The A330 and A343 have a largely identical wing. With the A340 long dead Airbus used the A330neo as an opportunity to strip down and remove unneeded structure that was in place for the A340 and higher MTOWs.
 
tommy1808
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 10:10 am

FluidFlow wrote:
tommy1808 wrote:
FluidFlow wrote:
According to wikipedia (I know it is not a reliable source but it has easy access), the A339 gained 6.2% OEW over the A333.


yeah, and that weight is not supported by the sources linked, but there is one user that always edits the A339 weight back up when it is corrected.

Hifly has registration specific files on its website and their A339 is only 2.140 Kg or ~1.5% heavier than their A333, while having 86 more installed seats....
https://hifly.aero/public/uploads/2019/ ... 9H-HFC.pdf
https://hifly.aero/public/uploads/2019/ ... -TKY-1.pdf

Airbus had the option to slim down a wing made for a 275t aircraft to support no more than 251t when making the Neo.

best regards
Thomas


That are really interesting numbers thanks for the infos. So the wing on the A339 is "slimmed" down? Or did Airbus not opt for the weight loss? I did not know the old A333 wing was designed for 275t MTOW. That was very ambitious? Though it must have been coming from the A343.


The A340 and A330 wing are the same. Every A330 made when the A342/3 was still being produced has literally the same wing, including all the structure to attach the two outboard CFMs and just wasn´t outfitted with the associated fuel lines etc. pp. When the A340 production seized, those structural parts where removed/optimized, but with the Neo the wing got an overhaul and i am pretty sure they have taken every bit of weight out that they could, even if that may not be all that dramatic since it is still good for 251t, is quite a bit longer and is missing those CFM counter weights (but also the associated twisting forces they create). After all, it supports more TOW, has heavier engines and is still just marginally heavier than the classic, and that has to come from somewhere. The wing is the obvious place to look.

best regards
Thomas
Well, there is prophecy in the bible after all: 2 Timothy 3:1-6
 
783211
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 11:35 am

FluidFlow wrote:
According to wikipedia (I know it is not a reliable source but it has easy access), the A339 gained 6.2% OEW over the A333, translated to the 777X that is 10.4t on additional OEW. Mind that the 6.2% include the engines and the Trent-7000 only gained 300kg dry weight over the Trent-700 (roughly 5%). The GE9X seems to be over 10% heavier than the previous GE engines on the 77W. That leads to more strengthening needed compared to the work that was needed on the 339. So Boeing will have a hard time to keep the OEW increase at 6.2%.

If Airbus managed an increase of 6.2% on engines that are 5% heavier with a slight stretch, Boeing will be very good if they can manage a 10% increase in OEW on 10% heavier engines.

10% increase of OEW on the 779 from the 77W would be around 183t, what seems to match the performance data from zeke.
Combined with the fact that Boeing has not been able to keep 779 orders and has a very hard time to sell more seems to indicate that the 779 will not beat expectations but is more or less hitting the targets set out at launch 2013 (one year before the 339). So the level of technological advances that was going into the two is similar. Boeing has about 5 years more time compared to the 339 to get things better but I do not see how they can reduce the OEW increase below 10% when the engines get so much heavier.


As a matter of fact, there's an error in the EASA TYPE-CERTIFICATE DATA SHEET for the Trent-700 engine; the weight of the nacelle is excluded, which is not correct.

The dry engine weight for the Trent 700 engine, not including fluids but including nacelle EBU is 6160 kg.

Page 6:
https://www.easa.europa.eu/sites/default/files/dfu/EASA%20E042%20TCDS%20issue%2006_Trent%20700.pdf

The dry engine weight for the very similar Trent 500 engine, not including fluids and nacelle EBU, is 4990 kg

https://www.easa.europa.eu/sites/default/files/dfu/EASA-TCDS-E.060_Rolls--Royce_plc_RB211_Trent_500_series_engines-01-26102007.pdf

Hence, in a like-for-like configuration, the two Trent-7000 engines on the A330neo weigh more than 2 tonnes more than the two Trent-700 engines on the A330ceo.
 
FluidFlow
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 12:18 pm

Baldr wrote:
FluidFlow wrote:
According to wikipedia (I know it is not a reliable source but it has easy access), the A339 gained 6.2% OEW over the A333, translated to the 777X that is 10.4t on additional OEW. Mind that the 6.2% include the engines and the Trent-7000 only gained 300kg dry weight over the Trent-700 (roughly 5%). The GE9X seems to be over 10% heavier than the previous GE engines on the 77W. That leads to more strengthening needed compared to the work that was needed on the 339. So Boeing will have a hard time to keep the OEW increase at 6.2%.

If Airbus managed an increase of 6.2% on engines that are 5% heavier with a slight stretch, Boeing will be very good if they can manage a 10% increase in OEW on 10% heavier engines.

10% increase of OEW on the 779 from the 77W would be around 183t, what seems to match the performance data from zeke.
Combined with the fact that Boeing has not been able to keep 779 orders and has a very hard time to sell more seems to indicate that the 779 will not beat expectations but is more or less hitting the targets set out at launch 2013 (one year before the 339). So the level of technological advances that was going into the two is similar. Boeing has about 5 years more time compared to the 339 to get things better but I do not see how they can reduce the OEW increase below 10% when the engines get so much heavier.


As a matter of fact, there's an error in the EASA TYPE-CERTIFICATE DATA SHEET for the Trent-700 engine; the weight of the nacelle is excluded, which is not correct.

The dry engine weight for the Trent 700 engine, not including fluids but including nacelle EBU is 6160 kg.

Page 6:
https://www.easa.europa.eu/sites/default/files/dfu/EASA%20E042%20TCDS%20issue%2006_Trent%20700.pdf

The dry engine weight for the very similar Trent 500 engine, not including fluids and nacelle EBU, is 4990 kg

https://www.easa.europa.eu/sites/default/files/dfu/EASA-TCDS-E.060_Rolls--Royce_plc_RB211_Trent_500_series_engines-01-26102007.pdf

Hence, in a like-for-like configuration, the two Trent-7000 engines on the A330neo weigh more than 2 tonnes more than the two Trent-700 engines on the A330ceo.


Very many thanks for that, what makes sense I was first a bit shocked how small the differences were but did not put the effort in to research why that was.
 
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 12:49 pm

morrisond wrote:
flipdewaf wrote:
morrisond wrote:

Luckily the 777X increased the aspect ratio from 9:1 to 10:1 then.


High AR is a double whammy! Longer is worse for weight and looser chord means lower thickness means even heavier. If we take the WL^3/ thickness scaling parameter of two wings of identical area and give one a 10% higher AR then you get a quadruple whammy (nearly), not only are you increasing span but you are decreasing thickness (assumption of constant t/c).
morrisond wrote:

I know simplistic scaling doesn't work - I didn't say it did. Basically my suggestion is that the A350 wing might be lighter than what Fred's model is showing - as in it's better - which as its carbon could make his estimate on 777X high.


The A35k is saving weight in the fuselage (by being slightly smaller, that old chestnut) having a lower MTOW so needing a lighter propulsion system and having a slightly lower capacity so needing less cabin furnishings. It’s saves a bunch of weight in the gear by the same mechanism as the propulsion system. Smaller feathers also make for lighter aircraft.

Incidentally all those things that make an aircraft light and optimised for low fuel burn pax running don’t help nearly so much on the world of freight, the higher the specific range the bigger the range hit from adding freight capability to MZFW.

Fred


Sent from my iPad using Tapatalk


Hi Fred - the A350 is marginally smaller than the 77W - you are talking 4" in Height and 8" width. The passenger Cabins and lengths of the A351 and 77W are nearly identical. You can cram 10W into an A351 - its been done.

I get that every little bit will be lighter.

What I am really wondering about is what I wrote about above given the OEW weight difference between A351 and 77W is about 20T

Quoting Myself

"The other way to look at it is how does the A351 weigh so much less than the similar sized 77W - when the wings and engines of the 350 are only about 5T less.

By some estimates the 350 saves another 15T on top of that with similar seating. If the engines and Wing are 61.6T (Wings 43.6 and Engines and about another 18T including nacelles and accessories) and the MEW weight is about 129T you are saving 15T tons on the remaining 67.4T or about 22.2%.

That seems pretty extreme when the weight savings on the wing is only about 6.4%.

It would make more sense that the 350 wing is lighter than 43.6T (greater than a 3T difference) and maybe the delta between the 77W and 77X is maybe not 9T."

I know the 350 wing is about 3% larger than the 77W. You are showing a weight loss of 6.4% on the wing - applying the 20T over the 129T MEW would be about 15.5%. So maybe 10-12% lighter due to the bigger size all things being equal. But they aren't equal as the 350 wing is Carbon vs Metal.

Take the 350 wing to an 15.5% weight loss and that is another 4T off it putting it under 40T and then the delta to what you are assuming on the 777Xf which would then be 13T would be pretty extreme.

I think the 777X wing will be heavier - but 5T vs 9T sounds more reasonable, which still has me assuming the 777X will be under 180T. 167T 77W + 3T Engines + 3T stretch + 5T wing less 2-4T less systems and interior weight - then some more for Bigger windows, stronger wingbox, heavier upper frames.


The weight reduction on the A350 composite centre wing box (i.e. 50% composite content by weight) is about 16% over that of a conventional all metal centre wing box.

The centre wing box on the 777X is all metal -- just like the centre wing box on the 777Classic.

Page 11:
http://www.ewshm2014.com/Documents/Nantes_Airbus.pdf

NB: The data for the A330 centre wing box in the document is not correct. The dimensions represent the centre wing box of the A340-500/-600 and not that of the A330 centre wing box -- i.e. length is 6.9 metres which is equivalent to 13 A330/A340 fuselage frames. The centre wing box of the A330 and the original A340 has a length of 5.33 metres which is equivalent to 10 A330/A340 fuselage frames. Wing growth on the A345/A346 was achieved with an insert running the length of the wing, spanning three fuselage frame pitches at the root and tapering out to the tip. Nevertheless, it's interesting to note that the centre wing box on the A350 is 37% lighter than the all metal centre wing box on the A345/A346
 
morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 1:22 pm

flipdewaf wrote:
morrisond wrote:
flipdewaf wrote:
High AR is a double whammy! Longer is worse for weight and looser chord means lower thickness means even heavier. If we take the WL^3/ thickness scaling parameter of two wings of identical area and give one a 10% higher AR then you get a quadruple whammy (nearly), not only are you increasing span but you are decreasing thickness (assumption of constant t/c).


The A35k is saving weight in the fuselage (by being slightly smaller, that old chestnut) having a lower MTOW so needing a lighter propulsion system and having a slightly lower capacity so needing less cabin furnishings. It’s saves a bunch of weight in the gear by the same mechanism as the propulsion system. Smaller feathers also make for lighter aircraft.

Incidentally all those things that make an aircraft light and optimised for low fuel burn pax running don’t help nearly so much on the world of freight, the higher the specific range the bigger the range hit from adding freight capability to MZFW.

Fred


Sent from my iPad using Tapatalk


Hi Fred - the A350 is marginally smaller than the 77W - you are talking 4" in Height and 8" width. The passenger Cabins and lengths of the A351 and 77W are nearly identical. You can cram 10W into an A351 - its been done.


There’s ~2t difference between them, I know you like to ignore fuselage weight but it’s there.
morrisond wrote:

I get that every little bit will be lighter.

What I am really wondering about is what I wrote about above given the OEW weight difference between A351 and 77W is about 20T

Quoting Myself

"The other way to look at it is how does the A351 weigh so much less than the similar sized 77W - when the wings and engines of the 350 are only about 5T less.

The propulsion system itself is about 5t different.
morrisond wrote:

By some estimates the 350 saves another 15T on top of that with similar seating. If the engines and Wing are 61.6T (Wings 43.6 and Engines and about another 18T including nacelles and accessories) and the MEW weight is about 129T you are saving 15T tons on the remaining 67.4T or about 22.2%.

That seems pretty extreme when the weight savings on the wing is only about 6.4%.

A similar spanned (although larger in area) wing that has to lift 6.4% less in the limit case has remarkably 6.4% lower weight? Hardly surprising for a structure that’s already highly optimised. We also need to remember that the A35k has a lower t/c than it’s sister aircraft.
morrisond wrote:

It would make more sense that the 350 wing is lighter than 43.6T (greater than a 3T difference) and maybe the delta between the 77W and 77X is maybe not 9T."


Would make more sense or fit your narrative better?
morrisond wrote:

I know the 350 wing is about 3% larger than the 77W. You are showing a weight loss of 6.4% on the wing - applying the 20T over the 129T MEW would be about 15.5%. So maybe 10-12% lighter due to the bigger size all things being equal. But they aren't equal as the 350 wing is Carbon vs Metal.

Maybe carbon isn’t the panacea you suggest? I mean look at the monumental weight savings the B787 made over the A330... especially when you consider the huge weight savings the 787 systems bring...
morrisond wrote:

Take the 350 wing to an 15.5% weight loss and that is another 4T off it putting it under 40T and then the delta to what you are assuming on the 777Xf which would then be 13T would be pretty extreme.


Or let’s just not pull stuff out of thin air and notice that a 184t 779x with associated aero we would expect from its configuration and SFC expected from a very good GE9x would give the range as stated by Boeing. Occasionally razor, the explanation with fewest assumptions is usually correct.
morrisond wrote:

I think the 777X wing will be heavier - but 5T vs 9T sounds more reasonable,

Based on what?
morrisond wrote:

which still has me assuming the 777X will be under 180T. 167T 77W + 3T Engines + 3T stretch + 5T wing less 2-4T less systems and interior weight - then some more for Bigger windows, stronger wingbox, heavier upper frames.

Are you trying to say that the wing box isn’t the wing? Yeah, now it makes sense. The wing is 5t heavier but the wing box is 4t heavier. We agree.

What is the 2-4t less “systems”? What are the “systems”? I mean to think it will be 2-4t less I guess you have an estimate of what it actually weighs? Are the 77W system currently ~6t of your weight estimate? Or are they 15t?

Fred


Sent from my iPad using Tapatalk


Fred - all you have to do is look at Zeke's fuel flow numbers to figure out that something doesn't make sense with Boeing's numbers. He has fuel flow numbers similar to 77W for the 77X when the engines have 10% better SFC and the aero on the aircraft is 3-4% better due to the longer higher aspect ratio wing. If the Aircraft isn't any better in fuel flow the whole thing seems like a monumental waste of time and money. Yes I I know slightly longer - but if all you are getting is enough to offset the increase in length.

Boeing is also saying it's better than an A351 on a per seat basis. Fuel flows in the mid 8,000 lbs per hour don't make sense when it only seats 12% more.

Boeing could be assuming that the 777X is carrying some cargo in it's calc's which would help to explain the difference.
 
morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 1:27 pm

FluidFlow wrote:
According to wikipedia (I know it is not a reliable source but it has easy access), the A339 gained 6.2% OEW over the A333, translated to the 777X that is 10.4t on additional OEW. Mind that the 6.2% include the engines and the Trent-7000 only gained 300kg dry weight over the Trent-700 (roughly 5%). The GE9X seems to be over 10% heavier than the previous GE engines on the 77W. That leads to more strengthening needed compared to the work that was needed on the 339. So Boeing will have a hard time to keep the OEW increase at 6.2%.

If Airbus managed an increase of 6.2% on engines that are 5% heavier with a slight stretch, Boeing will be very good if they can manage a 10% increase in OEW on 10% heavier engines.

10% increase of OEW on the 779 from the 77W would be around 183t, what seems to match the performance data from zeke.
Combined with the fact that Boeing has not been able to keep 779 orders and has a very hard time to sell more seems to indicate that the 779 will not beat expectations but is more or less hitting the targets set out at launch 2013 (one year before the 339). So the level of technological advances that was going into the two is similar. Boeing has about 5 years more time compared to the 339 to get things better but I do not see how they can reduce the OEW increase below 10% when the engines get so much heavier.


On sales.

Ignoring of course the BA order in 2019 for 18 firm and of course this little event called COVID.
 
Okcflyer
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 1:37 pm

zeke wrote:
morrisond wrote:
How does anything you wrote have anything to do with what I wrote? Mine was a reponse to something entirely different.


Your comments on bending moments is fundamentally flawed as you do no understand the systems.

morrisond wrote:
But it seems like Boeing has been able to change the camber as well since 2009 on the 300ER and it was back ported to the first gen 777's as well


No drooped ailerons is not variable camber, all Airbus FBW have been using drooped ailerons for the past 30+ years for load alleviation and lift generation.

The A350 is able to move the lift distribution in flight, when its heavy the lift distribution is moved closer to the fuselage, when its lighter its moved away, this results in lower bending moments and a lighter wing.

morrisond wrote:
Is Medium any better than WIKI? They also state in the article that the 77X should be able to carry many tons more than the A351 which if they are right on the OEW weight even at 184T with MZFW of 255T (71T of lift) can't really be true can it based on what you have seen the A351 can lift (about 75T to MZFW)?


Medium is different from wiki as its original content where authors put their real name to it. Many articles I read also have github repositories where you can replicate and modify their work. The OEW he has used for the -1000 is too high, all of our -1000s are a few tonnes under 150 tonnes, so the real life numbers are around 7 tonnes better than his article.

When it comes to empty weights Boeing has given us a data points on where they see their nominal marketing payload and range, we also have their comments on the improvements relative to the 77W. If you try and claim the OEW for the 779 is around 170 tonnes, it means the fuel burn is 1 tonne an hour higher than it would be if the OEW was at 184 tonnes, because we know they marketing datapoint of marketing payload at marketing range takes off at MTOW.

In this table below I have done a quick demonstration of what the fuel burns would be if the A150-1000 OEW was 150 tonnes or 155 tonnes, and the 777-9 OEW was 170 tonnes or 184 tonnes, in both cases I have assumed that the aircraft land with OEW+ passengers+7000 kg of fuel and they takeoff at MTOW (which is what the marketing range is based upon).

If we look at the OEW of 155 tonnes for the A350-1000, the fuel burn is below what Airbus Flysmart calculates the fuel burn wll be for 8700 nm, where it is in close correlation with the 150 tonne OEW numbers. I know where I work all of our -1000s are below 150 tonnes.

For the 777-9 if you are saying the OEW is 170 tonnes, it means the fuel burn per hour must be adjusted higher, to a level higher than the 77W which is not reasonable, with a OEW of 184 tonnes, the fuel burn per hour is closer to the 77W which is what we expect for the 777-9.

https://i.ibb.co/n3hJTvg/779-OEW.jpg

Image


Do you believe your own numbers?

If they are ture, it's means the B779 would be 8% more fuel per pax on a 1500m shorter trip.

Do you believe any airline, including your own, would have signed up for that? Bigger airplane that burns more per seat?
 
morrisond
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Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 1:42 pm

Baldr wrote:
morrisond wrote:
flipdewaf wrote:
High AR is a double whammy! Longer is worse for weight and looser chord means lower thickness means even heavier. If we take the WL^3/ thickness scaling parameter of two wings of identical area and give one a 10% higher AR then you get a quadruple whammy (nearly), not only are you increasing span but you are decreasing thickness (assumption of constant t/c).


The A35k is saving weight in the fuselage (by being slightly smaller, that old chestnut) having a lower MTOW so needing a lighter propulsion system and having a slightly lower capacity so needing less cabin furnishings. It’s saves a bunch of weight in the gear by the same mechanism as the propulsion system. Smaller feathers also make for lighter aircraft.

Incidentally all those things that make an aircraft light and optimised for low fuel burn pax running don’t help nearly so much on the world of freight, the higher the specific range the bigger the range hit from adding freight capability to MZFW.

Fred


Sent from my iPad using Tapatalk


Hi Fred - the A350 is marginally smaller than the 77W - you are talking 4" in Height and 8" width. The passenger Cabins and lengths of the A351 and 77W are nearly identical. You can cram 10W into an A351 - its been done.

I get that every little bit will be lighter.

What I am really wondering about is what I wrote about above given the OEW weight difference between A351 and 77W is about 20T

Quoting Myself

"The other way to look at it is how does the A351 weigh so much less than the similar sized 77W - when the wings and engines of the 350 are only about 5T less.

By some estimates the 350 saves another 15T on top of that with similar seating. If the engines and Wing are 61.6T (Wings 43.6 and Engines and about another 18T including nacelles and accessories) and the MEW weight is about 129T you are saving 15T tons on the remaining 67.4T or about 22.2%.

That seems pretty extreme when the weight savings on the wing is only about 6.4%.

It would make more sense that the 350 wing is lighter than 43.6T (greater than a 3T difference) and maybe the delta between the 77W and 77X is maybe not 9T."

I know the 350 wing is about 3% larger than the 77W. You are showing a weight loss of 6.4% on the wing - applying the 20T over the 129T MEW would be about 15.5%. So maybe 10-12% lighter due to the bigger size all things being equal. But they aren't equal as the 350 wing is Carbon vs Metal.

Take the 350 wing to an 15.5% weight loss and that is another 4T off it putting it under 40T and then the delta to what you are assuming on the 777Xf which would then be 13T would be pretty extreme.

I think the 777X wing will be heavier - but 5T vs 9T sounds more reasonable, which still has me assuming the 777X will be under 180T. 167T 77W + 3T Engines + 3T stretch + 5T wing less 2-4T less systems and interior weight - then some more for Bigger windows, stronger wingbox, heavier upper frames.


The weight reduction on the A350 composite centre wing box (i.e. 50% composite content by weight) is about 16% over that of a conventional all metal centre wing box.

The centre wing box on the 777X is all metal -- just like the centre wing box on the 777Classic.

Page 11:
http://www.ewshm2014.com/Documents/Nantes_Airbus.pdf

NB: The data for the A330 centre wing box in the document is not correct. The dimensions represent the centre wing box of the A340-500/-600 and not that of the A330 centre wing box -- i.e. length is 6.9 metres which is equivalent to 13 A330/A340 fuselage frames. The centre wing box of the A330 and the original A340 has a length of 5.33 metres which is equivalent to 10 A330/A340 fuselage frames. Wing growth on the A345/A346 was achieved with an insert running the length of the wing, spanning three fuselage frame pitches at the root and tapering out to the tip. Nevertheless, it's interesting to note that the centre wing box on the A350 is 37% lighter than the all metal centre wing box on the A345/A346


Great find on the weight of the Wingboxes - so an A350XWB 319T Wingbox only weighs 5.1T? Yet Fred has the 352T 77X gaining 4T on top of the 77W which presumably would be about 7T as it lifts more but metal making it weigh about the same as the A380 wingbox that can lift what 575T?

Ok then.
 
FluidFlow
Posts: 1004
Joined: Wed Apr 10, 2019 6:39 am

Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 1:49 pm

morrisond wrote:
FluidFlow wrote:
According to wikipedia (I know it is not a reliable source but it has easy access), the A339 gained 6.2% OEW over the A333, translated to the 777X that is 10.4t on additional OEW. Mind that the 6.2% include the engines and the Trent-7000 only gained 300kg dry weight over the Trent-700 (roughly 5%). The GE9X seems to be over 10% heavier than the previous GE engines on the 77W. That leads to more strengthening needed compared to the work that was needed on the 339. So Boeing will have a hard time to keep the OEW increase at 6.2%.

If Airbus managed an increase of 6.2% on engines that are 5% heavier with a slight stretch, Boeing will be very good if they can manage a 10% increase in OEW on 10% heavier engines.

10% increase of OEW on the 779 from the 77W would be around 183t, what seems to match the performance data from zeke.
Combined with the fact that Boeing has not been able to keep 779 orders and has a very hard time to sell more seems to indicate that the 779 will not beat expectations but is more or less hitting the targets set out at launch 2013 (one year before the 339). So the level of technological advances that was going into the two is similar. Boeing has about 5 years more time compared to the 339 to get things better but I do not see how they can reduce the OEW increase below 10% when the engines get so much heavier.


On sales.

Ignoring of course the BA order in 2019 for 18 firm and of course this little event called COVID.


In general it shows that there is no run on the airframe, even if you order now, you will not get your hands on until 2025 probably later due to the very low production rate. Many people here believe demand will have recovered until than. So no airline sees the need to order because there are enough open production slots available. This means that offer outstrips demand. One reason is that the offer seems not compelling enough to drive sales in bad times.

Even the MAX was able to generate sales during this pandemic, LH just bought 787s and A350s (though they are far out). This frames get ordered in the worst of times because the demand is there. The 77X saw one positive conversion (SQ) since 2019 all the other news were order reductions.

So if the 77X would be so good (technically) or so economic (price + operating cost) we would see orders even now, but what we see is a massive reduction in the order book, the biggest one from the main customer who decided to invest in proven aircraft (787 and 350) because their specs are known and solid instead on investing in a product that should outcompete both due to technological advances.

Boeing also seems unable to stimulate demand by offering better performance than promised or cheaper pricing.
 
Opus99
Topic Author
Posts: 2200
Joined: Thu May 30, 2019 10:51 pm

Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 1:53 pm

morrisond wrote:
FluidFlow wrote:
According to wikipedia (I know it is not a reliable source but it has easy access), the A339 gained 6.2% OEW over the A333, translated to the 777X that is 10.4t on additional OEW. Mind that the 6.2% include the engines and the Trent-7000 only gained 300kg dry weight over the Trent-700 (roughly 5%). The GE9X seems to be over 10% heavier than the previous GE engines on the 77W. That leads to more strengthening needed compared to the work that was needed on the 339. So Boeing will have a hard time to keep the OEW increase at 6.2%.

If Airbus managed an increase of 6.2% on engines that are 5% heavier with a slight stretch, Boeing will be very good if they can manage a 10% increase in OEW on 10% heavier engines.

10% increase of OEW on the 779 from the 77W would be around 183t, what seems to match the performance data from zeke.
Combined with the fact that Boeing has not been able to keep 779 orders and has a very hard time to sell more seems to indicate that the 779 will not beat expectations but is more or less hitting the targets set out at launch 2013 (one year before the 339). So the level of technological advances that was going into the two is similar. Boeing has about 5 years more time compared to the 339 to get things better but I do not see how they can reduce the OEW increase below 10% when the engines get so much heavier.


On sales.

Ignoring of course the BA order in 2019 for 18 firm and of course this little event called COVID.

I don't know why people keep bringing up sales with the 777X like its the only large aircraft that is struggling to sell and everything else is flying off the shelves. A35K has not inked one deal since it entered service, but I believe it is a fantastic aircraft so here we are. that argument of relating performance to sales is not always watertight.

787-10 and 350-1000 entered service same time, one has inked 42 orders the other 0 but I'm sure people can see how I can't use that to judge performance of one or the other even though they are both 300+ seater aircraft
 
Eagleboy
Posts: 1867
Joined: Fri Dec 04, 2009 2:29 am

Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 2:07 pm

alberchico wrote:
Considering that there will be plenty of second hand 777-300's available at attractive prices for freighter conversions, this might not be the best time to launch a A350 cargo variant.

And A330ceo's if the want to maintain some commonality.
 
morrisond
Posts: 3414
Joined: Thu Jan 07, 2010 12:22 am

Re: A350F. Airbus looking to launch: Looking for customers

Thu May 06, 2021 2:21 pm

FluidFlow wrote:
morrisond wrote:
FluidFlow wrote:
According to wikipedia (I know it is not a reliable source but it has easy access), the A339 gained 6.2% OEW over the A333, translated to the 777X that is 10.4t on additional OEW. Mind that the 6.2% include the engines and the Trent-7000 only gained 300kg dry weight over the Trent-700 (roughly 5%). The GE9X seems to be over 10% heavier than the previous GE engines on the 77W. That leads to more strengthening needed compared to the work that was needed on the 339. So Boeing will have a hard time to keep the OEW increase at 6.2%.

If Airbus managed an increase of 6.2% on engines that are 5% heavier with a slight stretch, Boeing will be very good if they can manage a 10% increase in OEW on 10% heavier engines.

10% increase of OEW on the 779 from the 77W would be around 183t, what seems to match the performance data from zeke.
Combined with the fact that Boeing has not been able to keep 779 orders and has a very hard time to sell more seems to indicate that the 779 will not beat expectations but is more or less hitting the targets set out at launch 2013 (one year before the 339). So the level of technological advances that was going into the two is similar. Boeing has about 5 years more time compared to the 339 to get things better but I do not see how they can reduce the OEW increase below 10% when the engines get so much heavier.


On sales.

Ignoring of course the BA order in 2019 for 18 firm and of course this little event called COVID.


In general it shows that there is no run on the airframe, even if you order now, you will not get your hands on until 2025 probably later due to the very low production rate. Many people here believe demand will have recovered until than. So no airline sees the need to order because there are enough open production slots available. This means that offer outstrips demand. One reason is that the offer seems not compelling enough to drive sales in bad times.

Even the MAX was able to generate sales during this pandemic, LH just bought 787s and A350s (though they are far out). This frames get ordered in the worst of times because the demand is there. The 77X saw one positive conversion (SQ) since 2019 all the other news were order reductions.

So if the 77X would be so good (technically) or so economic (price + operating cost) we would see orders even now, but what we see is a massive reduction in the order book, the biggest one from the main customer who decided to invest in proven aircraft (787 and 350) because their specs are known and solid instead on investing in a product that should outcompete both due to technological advances.

Boeing also seems unable to stimulate demand by offering better performance than promised or cheaper pricing.


The reason we are even talking about the 77X in this thread is to find out how capable a potential 777XF would be to see where the 350F needs to be roughly.

So not that it matters - But Yes order reductions due to Covid - a lot due to ASC 606 which Airbus does not report on. I can't find any Airbus sales of the A351 in the last 5 years other than 8 to a start-up - Starlux airlines - lets see how many of those get delivered.

https://en.wikipedia.org/wiki/List_of_A ... deliveries

A lot of A351's have been switched to A359 which may be due to the 351 engines having issues and reports of operators wanting more thrust - which leads me back to the 350F may need a MTOW boost and bump in thrust.

What combined 777X and 351 sales in the last 5 years are also telling us is that there is not much demand for expensive large aircraft. Operators bought a lot of 77W which are still quite young and not materially different in size than A351 or 779. Until we get to that replacement cycle (later this decade) I doubt we will see much demand for either.

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