morrisond
Posts: 2469
Joined: Thu Jan 07, 2010 12:22 am

Re: 777X vs A350 CASM

Thu Feb 20, 2020 1:19 pm

flipdewaf wrote:
morrisond wrote:
mjoelnir wrote:

Your 12,000 lbs / 5.5 t payload difference is an assumption and a bad one at that. As Boeing states the MZFW for the 777-9, but neither MSP nor OEW, you can not find your number in regards to Boeing statements.
The only way is to look at the OEW of the 777-300ER, 186 t, and assume a reasonable increase of the OEW in regards to the stretch of the fuselage, heavier engines and new bigger and heavier wing. The upper point is fixed with the MZFW of 255 t.

I assumed a 68 t MSP for the A350-1000 resulting from the MZFW of 233 t and a conservative OEW of 155 t. Real world numbers seem to reach 70 t.

If we assume a 5.5 t difference in MSP between the 777-9 and A350-1000 and assume the MSP for the A350-1000 with 68 t, than the 777-9 should offer a MSP of 73.5 t.
That would mean, that the OEW of the 777-9 would be 179.5 t. (255-73.5)
The OEW increase over and above the 777-300ER would than be only 11.5 t. I would say you are operating with rather optimistic numbers.

Increase in length, 2.2 each meter (same number as the stretch from the -200 to the -300) 3 m stretch gives us 6.6 t.
Engines, the GE9X will be heavier than the GE90-115B. A very conservative 1 t per engine. 2 t
(The numbers I found for the GE9X weight are astonishingly high so I disregard them here, the original plan was the GE9X coming out lighter than the GE90-115B, but that seems to have been a misconception. Perhaps some early estimates of the OEW increase are with lighter engines)
That would leave about 2.9 t for all other changes.

The other changes.
- bigger windows. weight increase as windows are heavier than skin. Not a lot each window, but it adds up.
- lower height of frames (to increase inside diameter) should increase weight of the fuselage.
- Eventual strengthening of some areas of the fuselage to match increased MZFW and MLW.
- The new big wing with folding wing tips should be heavier, though it is made from CFRP. It is far bigger than on the 777-300ER and the hinges and actuators for the folding tips are plain additional weight.

I would assume an OEW increase over above the 777-300ER of 15 t is quite conservative. That would bring the MSP of the 777-9 down to 70 t.


That is a good list. However you also have to look at where Boeing could have saved weight.

I believe they redid the avionics to use lighter 787 systems.

Interior fittings could be a lot lighter by using 787 tech as well.

It has new gear and a new wing box as well. MLW will have gone up - but you are talking 25 years of design time - you would think they could have taken some weight out here and there.

They have known the A351 numbers for some time - you would think they would have spent quite a bit of time trying to take weight out of it.

Yes I'm sure it will be heavier but maybe not as heavy as some are expecting.

But no way of knowing until the numbers are out.

If it’s not heavy then why is it using so much fuel to get 426pax to 7285nm. I would expect that number to be significantly higher with reduced fuel fractions ( lower slope on first section of payload/range chart).

Either Boeing are holding something back, it’s overweight but the aero is good but the payload availability not or the structures are good but the aero/engines stink.

My gut says Boeing are holding something back but I’m not quite sure what/why.

Fred


Sent from my iPhone using Tapatalk


I would agree they are holding something back. No way of knowing until the final numbers are released.

When you think about it what is left of the Original 777W?

The outer mold line of the nose and cross section?

New Wing, new tail, new gear, new wing box, a lot of new systems, new interior fuselage structure.

The Original 777 was described as very overbuilt. Given the 777x wing/fuselage structure failed almost perfectly at 149% (missed by 1%) you would have to assume they have shaved the margins quite a bit.

This is essentially a brand new aircraft and probably should have certified as such.

The 777X may have about as much in common with the 777W/L/F as the F18 A/B/C/D does with the F18 E/F.
 
WayexTDI
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 1:39 pm

Matt6461 wrote:
kitplane01 wrote:
Matt6461 wrote:
779 is definitely more efficient than A35K.


How do you know this? I cannot find a source for such information.


My source is Leeham's analysis (Bjorn's), which is behind a paywall and I'm no longer a subscriber.

Plus the simple fact that the 777-9 has been ordered at all tells me it's more efficient than A35K. With limited exceptions, airlines don't order larger planes unless they're more efficient.

Those aircraft also sold, does that make them efficient?
- 717-200 (156 frames);
- A318 (80 frames);
- 737-600 (69 frames);
- A340-600 (34 frames);
- A340-500 (97 frames);
- A380 (242 frames produced so far, 9 on backorder).

Just because a product sells doesn't mean it's more efficient; there are many variables to consider, efficiency is just one of them.
 
astuteman
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Joined: Mon Jan 24, 2005 7:50 pm

Re: 777X vs A350 CASM

Thu Feb 20, 2020 1:39 pm

RJMAZ wrote:
enzo011 wrote:
This myth needs to die. Just because Boeing had to adjust their range figures and capacity figures because they were out of date and using 1970's standards and seating and weights before everyone got fat, doesn't mean Airbus needs to readjust now as well.

I collected data from hundreds of A350-900 and 787 flights a couple years ago. The original purpose was just to compare the actual fuel burn. Quite a few were on the same route and day. I did notice a very small 1-2% difference which would make the myth plausible.

In the case of the 787 it has one payload range chart. The GenX was maybe 0.5% better than Trent 1000 but I did not have enough data points to be more than 90% certain.

I also did a few 737-800 and A320CEO flights on a handful of transatlantic flights and noticed a similar 1-2% trend. But none of these were on the same day.


I think I may have a plausible explanation for that 1-2% trend.
In the ACAPs Airbus use a density for their fuel of 0.785kg/l whereas Boeing use 0.8kg/l - 2% more dense than Airbus.
Hence if you equalise the fuel density between the two (doesn't matter which way you do it) for a given range the Airbus will lose a payload capability equal to 2% of the fuel load at that range, compared to the range/payload chart figures.
As the 787 and A359 are typically taking c. 100t of fuel on very long haul flights, that would equate to a 2t payload penalty for the A350-900 compared to the ACAP.

Other than that, I think the charts are pretty representative.

There is no huge gulf in plausibility such as that promulgated by one particular member with too many "m's" in his username....

Rgds
 
mjoelnir
Posts: 9387
Joined: Sun Feb 03, 2013 11:06 pm

Re: 777X vs A350 CASM

Thu Feb 20, 2020 2:06 pm

astuteman wrote:
RJMAZ wrote:
enzo011 wrote:
This myth needs to die. Just because Boeing had to adjust their range figures and capacity figures because they were out of date and using 1970's standards and seating and weights before everyone got fat, doesn't mean Airbus needs to readjust now as well.

I collected data from hundreds of A350-900 and 787 flights a couple years ago. The original purpose was just to compare the actual fuel burn. Quite a few were on the same route and day. I did notice a very small 1-2% difference which would make the myth plausible.

In the case of the 787 it has one payload range chart. The GenX was maybe 0.5% better than Trent 1000 but I did not have enough data points to be more than 90% certain.

I also did a few 737-800 and A320CEO flights on a handful of transatlantic flights and noticed a similar 1-2% trend. But none of these were on the same day.


I think I may have a plausible explanation for that 1-2% trend.
In the ACAPs Airbus use a density for their fuel of 0.785kg/l whereas Boeing use 0.8kg/l - 2% more dense than Airbus.
Hence if you equalise the fuel density between the two (doesn't matter which way you do it) for a given range the Airbus will lose a payload capability equal to 2% of the fuel load at that range, compared to the range/payload chart figures.
As the 787 and A359 are typically taking c. 100t of fuel on very long haul flights, that would equate to a 2t payload penalty for the A350-900 compared to the ACAP.

Other than that, I think the charts are pretty representative.

There is no huge gulf in plausibility such as that promulgated by one particular member with too many "m's" in his username....

Rgds


Fuel burn is according to weight not volume. You burn kilogram of fuel not cubic meter.

The only place were fuel density intrudes is in regards to max fuel in regards to volume. There the difference should be the other way round, Boeing expecting to fit more kg fuel in the same volume.
 
morrisond
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Joined: Thu Jan 07, 2010 12:22 am

Re: 777X vs A350 CASM

Thu Feb 20, 2020 2:12 pm

mjoelnir wrote:
astuteman wrote:
RJMAZ wrote:
I collected data from hundreds of A350-900 and 787 flights a couple years ago. The original purpose was just to compare the actual fuel burn. Quite a few were on the same route and day. I did notice a very small 1-2% difference which would make the myth plausible.

In the case of the 787 it has one payload range chart. The GenX was maybe 0.5% better than Trent 1000 but I did not have enough data points to be more than 90% certain.

I also did a few 737-800 and A320CEO flights on a handful of transatlantic flights and noticed a similar 1-2% trend. But none of these were on the same day.


I think I may have a plausible explanation for that 1-2% trend.
In the ACAPs Airbus use a density for their fuel of 0.785kg/l whereas Boeing use 0.8kg/l - 2% more dense than Airbus.
Hence if you equalise the fuel density between the two (doesn't matter which way you do it) for a given range the Airbus will lose a payload capability equal to 2% of the fuel load at that range, compared to the range/payload chart figures.
As the 787 and A359 are typically taking c. 100t of fuel on very long haul flights, that would equate to a 2t payload penalty for the A350-900 compared to the ACAP.

Other than that, I think the charts are pretty representative.

There is no huge gulf in plausibility such as that promulgated by one particular member with too many "m's" in his username....

Rgds


Fuel burn is according to weight not volume. You burn kilogram of fuel not cubic meter.

The only place were fuel density intrudes is in regards to max fuel in regards to volume. There the difference should be the other way round, Boeing expecting to fit more kg fuel in the same volume.


Interesting I didn't know modern aircraft could instantly calculate the weight of Fuel spewing through the nozzles and adjust accordingly.

What kind of system do they use to do that?
 
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Polot
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 2:17 pm

mjoelnir wrote:
astuteman wrote:
RJMAZ wrote:
I collected data from hundreds of A350-900 and 787 flights a couple years ago. The original purpose was just to compare the actual fuel burn. Quite a few were on the same route and day. I did notice a very small 1-2% difference which would make the myth plausible.

In the case of the 787 it has one payload range chart. The GenX was maybe 0.5% better than Trent 1000 but I did not have enough data points to be more than 90% certain.

I also did a few 737-800 and A320CEO flights on a handful of transatlantic flights and noticed a similar 1-2% trend. But none of these were on the same day.


I think I may have a plausible explanation for that 1-2% trend.
In the ACAPs Airbus use a density for their fuel of 0.785kg/l whereas Boeing use 0.8kg/l - 2% more dense than Airbus.
Hence if you equalise the fuel density between the two (doesn't matter which way you do it) for a given range the Airbus will lose a payload capability equal to 2% of the fuel load at that range, compared to the range/payload chart figures.
As the 787 and A359 are typically taking c. 100t of fuel on very long haul flights, that would equate to a 2t payload penalty for the A350-900 compared to the ACAP.

Other than that, I think the charts are pretty representative.

There is no huge gulf in plausibility such as that promulgated by one particular member with too many "m's" in his username....

Rgds


Fuel burn is according to weight not volume. You burn kilogram of fuel not cubic meter.

The only place were fuel density intrudes is in regards to max fuel in regards to volume. There the difference should be the other way round, Boeing expecting to fit more kg fuel in the same volume.

Density is kind of important if you are also taking about weight and available payload. Payload/range are weight vs range, not volume vs range, and the MTOW of an aircraft and any assumptions based off that is taking account weight of the fuel, not volume. Payloads may not be with full volumes of fuel.

Boeing’s 100t of fuel is a smaller volume than Airbus’s 100t of fuel. All else (fuel burn, etc) being equal an aircraft with Airbus’s volume of fuel will fly further because there is physically more fuel present.
 
astuteman
Posts: 7086
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 3:24 pm

mjoelnir wrote:
astuteman wrote:
RJMAZ wrote:
I collected data from hundreds of A350-900 and 787 flights a couple years ago. The original purpose was just to compare the actual fuel burn. Quite a few were on the same route and day. I did notice a very small 1-2% difference which would make the myth plausible.

In the case of the 787 it has one payload range chart. The GenX was maybe 0.5% better than Trent 1000 but I did not have enough data points to be more than 90% certain.

I also did a few 737-800 and A320CEO flights on a handful of transatlantic flights and noticed a similar 1-2% trend. But none of these were on the same day.


I think I may have a plausible explanation for that 1-2% trend.
In the ACAPs Airbus use a density for their fuel of 0.785kg/l whereas Boeing use 0.8kg/l - 2% more dense than Airbus.
Hence if you equalise the fuel density between the two (doesn't matter which way you do it) for a given range the Airbus will lose a payload capability equal to 2% of the fuel load at that range, compared to the range/payload chart figures.
As the 787 and A359 are typically taking c. 100t of fuel on very long haul flights, that would equate to a 2t payload penalty for the A350-900 compared to the ACAP.

Other than that, I think the charts are pretty representative.

There is no huge gulf in plausibility such as that promulgated by one particular member with too many "m's" in his username....

Rgds


Fuel burn is according to weight not volume. You burn kilogram of fuel not cubic meter.

The only place were fuel density intrudes is in regards to max fuel in regards to volume. There the difference should be the other way round, Boeing expecting to fit more kg fuel in the same volume.


Indeed.
And Airbus assume their fuel is 2% lighter than Boeing do.
But in the ACAP, on the R/P chart, they quote a maximum volume of fuel (e.g. 158,000l for the A350-1000).
At 0.785kg/l, the A350-1000 ACAP therefore assumes that the 158,000l of fuel at the fuel limit range of 8,500Nm weighs 125 tonnes.
At 0.8kg/l, that same maximum volume of fuel would weigh 127 tonnes.
That extra 2 tonnes has to come from somewhere.
And as it is still the same A350-1000, the DOW assumed won't changed.
So it MUST come from payload

It doesn't matter if you make the Airbus fuel load 2% heavier or the Boeing one 2% lighter.
But if we're trying to make comparisons, we should assume the same density for the same fuel load.

It's not like I'm a Boeing "fanboy" is it? :)

Rgds
 
morrisond
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 3:31 pm

morrisond wrote:
flipdewaf wrote:
morrisond wrote:

That is a good list. However you also have to look at where Boeing could have saved weight.

I believe they redid the avionics to use lighter 787 systems.

Interior fittings could be a lot lighter by using 787 tech as well.

It has new gear and a new wing box as well. MLW will have gone up - but you are talking 25 years of design time - you would think they could have taken some weight out here and there.

They have known the A351 numbers for some time - you would think they would have spent quite a bit of time trying to take weight out of it.

Yes I'm sure it will be heavier but maybe not as heavy as some are expecting.

But no way of knowing until the numbers are out.

If it’s not heavy then why is it using so much fuel to get 426pax to 7285nm. I would expect that number to be significantly higher with reduced fuel fractions ( lower slope on first section of payload/range chart).

Either Boeing are holding something back, it’s overweight but the aero is good but the payload availability not or the structures are good but the aero/engines stink.

My gut says Boeing are holding something back but I’m not quite sure what/why.

Fred


Sent from my iPhone using Tapatalk


I would agree they are holding something back. No way of knowing until the final numbers are released.

When you think about it what is left of the Original 777W?

The outer mold line of the nose and cross section?

New Wing, new tail, new gear, new wing box, a lot of new systems, new interior fuselage structure.

The Original 777 was described as very overbuilt. Given the 777x wing/fuselage structure failed almost perfectly at 149% (missed by 1%) you would have to assume they have shaved the margins quite a bit.

This is essentially a brand new aircraft and probably should have certified as such.

The 777X may have about as much in common with the 777W/L/F as the F18 A/B/C/D does with the F18 E/F.


So does anyone have insight on what is left from the 777W? Is this really a brand new state of the art aircraft hiding in an old wrapper?
 
StTim
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 3:32 pm

astuteman wrote:
mjoelnir wrote:
astuteman wrote:

I think I may have a plausible explanation for that 1-2% trend.
In the ACAPs Airbus use a density for their fuel of 0.785kg/l whereas Boeing use 0.8kg/l - 2% more dense than Airbus.
Hence if you equalise the fuel density between the two (doesn't matter which way you do it) for a given range the Airbus will lose a payload capability equal to 2% of the fuel load at that range, compared to the range/payload chart figures.
As the 787 and A359 are typically taking c. 100t of fuel on very long haul flights, that would equate to a 2t payload penalty for the A350-900 compared to the ACAP.

Other than that, I think the charts are pretty representative.

There is no huge gulf in plausibility such as that promulgated by one particular member with too many "m's" in his username....

Rgds


Fuel burn is according to weight not volume. You burn kilogram of fuel not cubic meter.

The only place were fuel density intrudes is in regards to max fuel in regards to volume. There the difference should be the other way round, Boeing expecting to fit more kg fuel in the same volume.


Indeed.
And Airbus assume their fuel is 2% lighter than Boeing do.
But in the ACAP, on the R/P chart, they quote a maximum volume of fuel (e.g. 158,000l for the A350-1000).
At 0.785kg/l, the A350-1000 ACAP therefore assumes that the 158,000l of fuel at the fuel limit range of 8,500Nm weighs 125 tonnes.
At 0.8kg/l, that same maximum volume of fuel would weigh 127 tonnes.
That extra 2 tonnes has to come from somewhere.
And as it is still the same A350-1000, the DOW assumed won't changed.
So it MUST come from payload

It doesn't matter if you make the Airbus fuel load 2% heavier or the Boeing one 2% lighter.
But if we're trying to make comparisons, we should assume the same density for the same fuel load.

It's not like I'm a Boeing "fanboy" is it? :)

Rgds


I agree the 158,000L would have more mass. The thing is for the range you require you wouldn't need that mass - based on fuel being metered by mass not volume as a smaller volume would contain the required enery.

Thus you could fuel more by about 2t to allow you to fly further.

Alternatively if Boeing were to use a lighter density for their fuel (and that is the maximum volume the 777X can contain) then it will actually fly a shorter distance as their is less fuel energy on board to consume.
 
mjoelnir
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 3:35 pm

morrisond wrote:
flipdewaf wrote:
morrisond wrote:

That is a good list. However you also have to look at where Boeing could have saved weight.

I believe they redid the avionics to use lighter 787 systems.

Interior fittings could be a lot lighter by using 787 tech as well.

It has new gear and a new wing box as well. MLW will have gone up - but you are talking 25 years of design time - you would think they could have taken some weight out here and there.

They have known the A351 numbers for some time - you would think they would have spent quite a bit of time trying to take weight out of it.

Yes I'm sure it will be heavier but maybe not as heavy as some are expecting.

But no way of knowing until the numbers are out.

If it’s not heavy then why is it using so much fuel to get 426pax to 7285nm. I would expect that number to be significantly higher with reduced fuel fractions ( lower slope on first section of payload/range chart).

Either Boeing are holding something back, it’s overweight but the aero is good but the payload availability not or the structures are good but the aero/engines stink.

My gut says Boeing are holding something back but I’m not quite sure what/why.

Fred


Sent from my iPhone using Tapatalk


I would agree they are holding something back. No way of knowing until the final numbers are released.

When you think about it what is left of the Original 777W?

The outer mold line of the nose and cross section?

New Wing, new tail, new gear, new wing box, a lot of new systems, new interior fuselage structure.

The Original 777 was described as very overbuilt. Given the 777x wing/fuselage structure failed almost perfectly at 149% (missed by 1%) you would have to assume they have shaved the margins quite a bit.

This is essentially a brand new aircraft and probably should have certified as such.

The 777X may have about as much in common with the 777W/L/F as the F18 A/B/C/D does with the F18 E/F.


The original 777-200 was overbuilt. MTOW 246.6 t, MLW 201.8, MZFW 190.5 t, OEW 134.8 t, MSP 55.7 t.

The 777-300ER IMO used up quite a bit of that overbuilt structural reserve.
MTOW 351.5 t, MLW 251.3, MZFW 273.7 t, OEW 167.8 t, MSP 69.9 t.

The fuselage breaking at 149% is actually no proof for Boeing having been able to shave off weight. The bigger frame and wings and higher pressure differential, could produce more load on certain areas.
 
morrisond
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 3:39 pm

mjoelnir wrote:
morrisond wrote:
flipdewaf wrote:
If it’s not heavy then why is it using so much fuel to get 426pax to 7285nm. I would expect that number to be significantly higher with reduced fuel fractions ( lower slope on first section of payload/range chart).

Either Boeing are holding something back, it’s overweight but the aero is good but the payload availability not or the structures are good but the aero/engines stink.

My gut says Boeing are holding something back but I’m not quite sure what/why.

Fred


Sent from my iPhone using Tapatalk


I would agree they are holding something back. No way of knowing until the final numbers are released.

When you think about it what is left of the Original 777W?

The outer mold line of the nose and cross section?

New Wing, new tail, new gear, new wing box, a lot of new systems, new interior fuselage structure.

The Original 777 was described as very overbuilt. Given the 777x wing/fuselage structure failed almost perfectly at 149% (missed by 1%) you would have to assume they have shaved the margins quite a bit.

This is essentially a brand new aircraft and probably should have certified as such.

The 777X may have about as much in common with the 777W/L/F as the F18 A/B/C/D does with the F18 E/F.


The original 777-200 was overbuilt. MTOW 246.6 t, MLW 201.8, MZFW 190.5 t, OEW 134.8 t, MSP 55.7 t.

The 777-300ER IMO used up quite a bit of that overbuilt structural reserve.
MTOW 351.5 t, MLW 251.3, MZFW 273.7 t, OEW 167.8 t, MSP 69.9 t.

The fuselage breaking at 149% is actually no proof for Boeing having been able to shave off weight. The bigger frame and wings and higher pressure differential, could produce more load on certain areas.


So what is left from the 777W then other than a few internal systems they did not update to 787 spec?
 
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Polot
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 3:40 pm

StTim wrote:
astuteman wrote:
mjoelnir wrote:

Fuel burn is according to weight not volume. You burn kilogram of fuel not cubic meter.

The only place were fuel density intrudes is in regards to max fuel in regards to volume. There the difference should be the other way round, Boeing expecting to fit more kg fuel in the same volume.


Indeed.
And Airbus assume their fuel is 2% lighter than Boeing do.
But in the ACAP, on the R/P chart, they quote a maximum volume of fuel (e.g. 158,000l for the A350-1000).
At 0.785kg/l, the A350-1000 ACAP therefore assumes that the 158,000l of fuel at the fuel limit range of 8,500Nm weighs 125 tonnes.
At 0.8kg/l, that same maximum volume of fuel would weigh 127 tonnes.
That extra 2 tonnes has to come from somewhere.
And as it is still the same A350-1000, the DOW assumed won't changed.
So it MUST come from payload

It doesn't matter if you make the Airbus fuel load 2% heavier or the Boeing one 2% lighter.
But if we're trying to make comparisons, we should assume the same density for the same fuel load.

It's not like I'm a Boeing "fanboy" is it? :)

Rgds


I agree the 158,000L would have more mass. The thing is for the range you require you wouldn't need that mass - based on fuel being metered by mass not volume as a smaller volume would contain the required enery.

Thus you could fuel more by about 2t to allow you to fly further.

No you can’t add 2T more fuel (at Airbus’s density) because you can’t physically fit any more fuel in the tanks. If you use Boeing’s density you must remove 2T of payload (assuming plane also has max possible payload) or else you will be over the legally allowed MTOW. Unless I’m misunderstanding you

Both Boeing and Airbus are assuming the same amount of energy per a L of fuel, they are just rounding mass density (not energy density) at different decimal points. Mass density (specific mass) is not the same thing as energy density. You should not be bringing energy into the discussion.
 
StTim
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 3:55 pm

Surely it is at the end of the day all about the energy contained in the fuel that is loaded.
 
morrisond
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 3:57 pm

StTim wrote:
Surely it is at the end of the day all about the energy contained in the fuel that is loaded.


JP-5 vs JP-7? :D
 
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Polot
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 4:01 pm

StTim wrote:
Surely it is at the end of the day all about the energy contained in the fuel that is loaded.

And Boeing and Airbus are both assuming that the fuel has the same energy. One just thinks (A350 fully loaded with fuel) that it ends up weighing 125 tons. The other thinks 127t. The volume is the same though.
 
morrisond
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 4:09 pm

I think they are just assuming different temperatures for the fuel - there can be a big difference in volume between Hot and Cold

https://www.ic.gc.ca/eic/site/mc-mc.nsf ... 04778.html

https://www.engineeringtoolbox.com/jet- ... _1944.html
 
StTim
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 4:18 pm

Surely they are using a standard grade fuel - eg Jet A1 (or pehaps on the US Jet A)

There are differences in density and Energy density.

Jet A
Denisty (@15C, 59F) 0.820 kg/l (6.84 lb/US gal)
Energy Density 35.3 MJ/L (9.8 kWh / L)

Jet A1
Denisty (@15C, 59F) 0.804 kg/l (6.71 lb/US gal)
Energy Density 34.7 MJ/L [13] (9.6 kWh / L)
 
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zeke
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 4:19 pm

astuteman wrote:

Indeed.
And Airbus assume their fuel is 2% lighter than Boeing do.
But in the ACAP, on the R/P chart, they quote a maximum volume of fuel (e.g. 158,000l for the A350-1000).
At 0.785kg/l, the A350-1000 ACAP therefore assumes that the 158,000l of fuel at the fuel limit range of 8,500Nm weighs 125 tonnes.
At 0.8kg/l, that same maximum volume of fuel would weigh 127 tonnes.
That extra 2 tonnes has to come from somewhere.
And as it is still the same A350-1000, the DOW assumed won't changed.
So it MUST come from payload

It doesn't matter if you make the Airbus fuel load 2% heavier or the Boeing one 2% lighter.
But if we're trying to make comparisons, we should assume the same density for the same fuel load.

It's not like I'm a Boeing "fanboy" is it? :)

Rgds


When refueling we order a final mass of fuel, the fuel delivery vehicle uplifts whatever volume of fuel it needs so the mass of fuel onboard is what is required. SG changes with temperature and where in the world fuel is loaded, however the mass onboard does not change. We would normally check the volume of fuel upliftedxSG plus the amount of fuel onboard at the start of refueling to see if it is in close agreement with what was ordered.

During flight as fuel is reduced in temperature, it is not unusual to see the SG increase, I can see the SG of the fuel in each tank in flight on the A350. After landing the fuel still onboard is normally cold, with a high SG, as warmer fuel is uplifted it is mixed with the fuel in the tank already. The A350 measures the fuel properties within the refueling circuit, and again in the tanks.

The only impact SG has on the payload range is on the part of the curve where the aircraft is fuel volume limited. Using a lower SG means the aircraft will not fly as far for the maximum volume of fuel that can be loaded into the aircraft.
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 4:23 pm

StTim wrote:
Surely they are using a standard grade fuel - eg Jet A1 (or pehaps on the US Jet A)

There are differences in density and Energy density.

Jet A
Denisty (@15C, 59F) 0.820 kg/l (6.84 lb/US gal)
Energy Density 35.3 MJ/L (9.8 kWh / L)

Jet A1
Denisty (@15C, 59F) 0.804 kg/l (6.71 lb/US gal)
Energy Density 34.7 MJ/L [13] (9.6 kWh / L)


The energy in Jet A1 can be calculated, it is a function of SG, the approximation for the lower heating value is -5220*SG+22777
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 4:25 pm

zeke wrote:
StTim wrote:
Surely they are using a standard grade fuel - eg Jet A1 (or pehaps on the US Jet A)

There are differences in density and Energy density.

Jet A
Denisty (@15C, 59F) 0.820 kg/l (6.84 lb/US gal)
Energy Density 35.3 MJ/L (9.8 kWh / L)

Jet A1
Denisty (@15C, 59F) 0.804 kg/l (6.71 lb/US gal)
Energy Density 34.7 MJ/L [13] (9.6 kWh / L)


The energy in Jet A1 can be calculated, it is a function of SG, the approximation for the lower heating value is -5220*SG+22777


Is the flow to the engines in Kg/hour rather than L/hour?
 
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 4:32 pm

zeke wrote:
astuteman wrote:

Indeed.
And Airbus assume their fuel is 2% lighter than Boeing do.
But in the ACAP, on the R/P chart, they quote a maximum volume of fuel (e.g. 158,000l for the A350-1000).
At 0.785kg/l, the A350-1000 ACAP therefore assumes that the 158,000l of fuel at the fuel limit range of 8,500Nm weighs 125 tonnes.
At 0.8kg/l, that same maximum volume of fuel would weigh 127 tonnes.
That extra 2 tonnes has to come from somewhere.
And as it is still the same A350-1000, the DOW assumed won't changed.
So it MUST come from payload

It doesn't matter if you make the Airbus fuel load 2% heavier or the Boeing one 2% lighter.
But if we're trying to make comparisons, we should assume the same density for the same fuel load.

It's not like I'm a Boeing "fanboy" is it? :)

Rgds


When refueling we order a final mass of fuel, the fuel delivery vehicle uplifts whatever volume of fuel it needs so the mass of fuel onboard is what is required. SG changes with temperature and where in the world fuel is loaded, however the mass onboard does not change. We would normally check the volume of fuel upliftedxSG plus the amount of fuel onboard at the start of refueling to see if it is in close agreement with what was ordered.

During flight as fuel is reduced in temperature, it is not unusual to see the SG increase, I can see the SG of the fuel in each tank in flight on the A350. After landing the fuel still onboard is normally cold, with a high SG, as warmer fuel is uplifted it is mixed with the fuel in the tank already. The A350 measures the fuel properties within the refueling circuit, and again in the tanks.

The only impact SG has on the payload range is on the part of the curve where the aircraft is fuel volume limited. Using a lower SG means the aircraft will not fly as far for the maximum volume of fuel that can be loaded into the aircraft.

Airbus/Boeing payload/range charts (that we the public can see) are not about how much fuel you ask for in weight vs volume you actually get though. They are assuming that the tank is filled up to a specific volume, and calculating weight from that. Both Airbus and Boeing will claim there is the same volume of fuel in the A350 in his example.

Obviously that is not how it works in the real world, but you have to account for the density differences if you really want a detailed comparison using payload/range charts. There is a reason why Airbus/Boeing outline their density assumption in the ACAPs, and why you don’t use ACAP charts for actual operations.
 
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 4:39 pm

StTim wrote:

Is the flow to the engines in Kg/hour rather than L/hour?


Correct, same with the flight plan.
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 4:54 pm

Polot wrote:
Airbus/Boeing payload/range charts (that we the public can see) are not about how much fuel you ask for in weight vs volume you actually get though. They are assuming that the tank is filled up to a specific volume, and calculating weight from that. Both Airbus and Boeing will claim there is the same volume of fuel in the A350 in his example.


That is not correct, the area I have circled in this payload range chart is the area where the aircraft is fuel volume limited. If you assume to assume a higher SG that has the effect of increasing range as more fuel mass is uplifted for the maximum fuel volume that can be loaded (like I have amended in blue on the chart).

In some of the record attempts in the past, aircraft were loaded with specially cooled fuel to enable them to uplift more fuel mass for the maximum fuel tank volume.


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Re: 777X vs A350 CASM

Thu Feb 20, 2020 4:59 pm

Matt6461 wrote:
kitplane01 wrote:
Matt6461 wrote:
779 is definitely more efficient than A35K.

How do you know this? I cannot find a source for such information.


My source is Leeham's analysis (Bjorn's), which is behind a paywall and I'm no longer a subscriber.

Plus the simple fact that the 777-9 has been ordered at all tells me it's more efficient than A35K. With limited exceptions, airlines don't order larger planes unless they're more efficient.

I think that's pretty noteworthy.

I posted about the overlap between current A350 customers and future 77x customers earlier.

We're told to trust that airlines have more accurate modeling than our back of the napkin scribbles, yet those airlines who would have every reason to just add more A350s are also taking 779s.

We will be told this is just posturing, but getting an order on the books implies a lot of work on behalf of the airlines and a financial commitment that is difficult to erase as well.

Apparently the airlines see value in 779 that people here can't seem to understand.
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 5:27 pm

Revelation wrote:
Matt6461 wrote:
kitplane01 wrote:
How do you know this? I cannot find a source for such information.


My source is Leeham's analysis (Bjorn's), which is behind a paywall and I'm no longer a subscriber.

Plus the simple fact that the 777-9 has been ordered at all tells me it's more efficient than A35K. With limited exceptions, airlines don't order larger planes unless they're more efficient.

I think that's pretty noteworthy.

I posted about the overlap between current A350 customers and future 77x customers earlier.

We're told to trust that airlines have more accurate modeling than our back of the napkin scribbles, yet those airlines who would have every reason to just add more A350s are also taking 779s.

We will be told this is just posturing, but getting an order on the books implies a lot of work on behalf of the airlines and a financial commitment that is difficult to erase as well.

Apparently the airlines see value in 779 that people here can't seem to understand.

My thoughts exactly. There are people who get paid for fleet planning and strategy and quite a few of them have come to conclusions that the 779 AND the 35K work for their airlines
 
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AECM
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 5:35 pm

I think that in certain companies the B779 extra cabin volume will be used more has 4 a class layout with First and the A35K has a 3 class layout without First
 
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Re: 777X vs A350 CASM

Thu Feb 20, 2020 10:28 pm

WayexTDI wrote:
Matt6461 wrote:
kitplane01 wrote:

How do you know this? I cannot find a source for such information.


My source is Leeham's analysis (Bjorn's), which is behind a paywall and I'm no longer a subscriber.

Plus the simple fact that the 777-9 has been ordered at all tells me it's more efficient than A35K. With limited exceptions, airlines don't order larger planes unless they're more efficient.

Those aircraft also sold, does that make them efficient?
- 717-200 (156 frames);
- A318 (80 frames);
- 737-600 (69 frames);
- A340-600 (34 frames);
- A340-500 (97 frames);
- A380 (242 frames produced so far, 9 on backorder).

Just because a product sells doesn't mean it's more efficient; there are many variables to consider, efficiency is just one of them.


If you're going to parody my point I'll just assume that further attempts to explain it are pointless.

I'll just note the A380 was for over a decade the most efficient plane flying and by certain metrics (DOC with cheap gas and cheap sales price) it is still more efficient than a 777-9.

Of course that doesn't mean the A380 was a good product.

Why not?

Master the sufficient/necessary distinction, look again at my statement about efficiency, and you will see why.
 
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 5:52 am

Revelation wrote:
Matt6461 wrote:
kitplane01 wrote:
How do you know this? I cannot find a source for such information.


My source is Leeham's analysis (Bjorn's), which is behind a paywall and I'm no longer a subscriber.

Plus the simple fact that the 777-9 has been ordered at all tells me it's more efficient than A35K. With limited exceptions, airlines don't order larger planes unless they're more efficient.

I think that's pretty noteworthy.

I posted about the overlap between current A350 customers and future 77x customers earlier.

We're told to trust that airlines have more accurate modeling than our back of the napkin scribbles, yet those airlines who would have every reason to just add more A350s are also taking 779s.

We will be told this is just posturing, but getting an order on the books implies a lot of work on behalf of the airlines and a financial commitment that is difficult to erase as well.

Apparently the airlines see value in 779 that people here can't seem to understand.


It is quite telling that all the airlines who ordered the 777-9 operate F. Even if a widebody airliner had the CASM of A321/Max200, they won't be chosen if they are unable to carry the number of high revenue seats airlines desire. If you look at the current long haul 77W configs of those airlines, except the ME airlines, all of them seat < 300, some even < 250. They need the additional space of 777-9. This does not mean 777-9 will have better/worse CASM, but I think CASM was probably the last requirement for choosing 777-9 over A35K (ok, maybe except EK).
 
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 6:53 am

I think A350-1000 presented in 2016 vs 777x presented for 2021 showed big difference...


2021 numbersfor both of them means that 778 is dead. If that statement is true can we assume that 350-1000 now is better and in that case with how much?

This should show that 350-1000 is very close to 779 and I assume that the actions of EK confirms this even that 779 has better engines. The question that will define 779 succes is how many years will it have better engines then 350-1000.
 
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 7:32 am

Revelation wrote:
...

I think that's pretty noteworthy.

I posted about the overlap between current A350 customers and future 77x customers earlier.

We're told to trust that airlines have more accurate modeling than our back of the napkin scribbles, yet those airlines who would have every reason to just add more A350s are also taking 779s.
...
Apparently the airlines see value in 779 that people here can't seem to understand.


You mention something interesting. Indeed, some major airlines decided to order the 777-9 despite the fact they already ordered the A350-1000. It is possible those airlines see a different application for each aircraft.

I am pretty sure people here will be able to provide us with a "rational" explanation. However, it appears that the A350-1000 did not completely erase the potential of the 777-9.

I guess airlines are also happy to have a stiff competition between the two aircraft manufacturers.
 
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 10:07 am

sabby wrote:
Revelation wrote:
Matt6461 wrote:

My source is Leeham's analysis (Bjorn's), which is behind a paywall and I'm no longer a subscriber.

Plus the simple fact that the 777-9 has been ordered at all tells me it's more efficient than A35K. With limited exceptions, airlines don't order larger planes unless they're more efficient.

I think that's pretty noteworthy.

I posted about the overlap between current A350 customers and future 77x customers earlier.

We're told to trust that airlines have more accurate modeling than our back of the napkin scribbles, yet those airlines who would have every reason to just add more A350s are also taking 779s.

We will be told this is just posturing, but getting an order on the books implies a lot of work on behalf of the airlines and a financial commitment that is difficult to erase as well.

Apparently the airlines see value in 779 that people here can't seem to understand.


It is quite telling that all the airlines who ordered the 777-9 operate F. Even if a widebody airliner had the CASM of A321/Max200, they won't be chosen if they are unable to carry the number of high revenue seats airlines desire. If you look at the current long haul 77W configs of those airlines, except the ME airlines, all of them seat < 300, some even < 250. They need the additional space of 777-9. This does not mean 777-9 will have better/worse CASM, but I think CASM was probably the last requirement for choosing 777-9 over A35K (ok, maybe except EK).


On an apples-apples comparison, do you think the 779 has **higher** CASM compared to narrow bodies?

If you're going by nominal seats in average configurations, sure, but that's a willfully blind comparison.

Airlines could absolutely put F in NB's; it just doesn't make sense at NB segment lengths.
 
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 10:31 am

oschkosch wrote:
I guess we will only know upon EIS of the 777x?


The first answer already says it all. Nice signature.


travelhound wrote:
StTim wrote:
They had to go bigger to get the economics of scale. This means that for the same payload/range that the A350K will have lower trip fuel figures. The 779 will however be able to take more further so to make it viable the airline has to know they will have sufficient revenue opportunities to require that additional lift.


The A350 has two engines to maintain, so does the B777-9. Same for pilots. I also believe the choice between A350 and B777-9 will not depend on fuel economy.
Unless of course GE pulled a rabbit out of the hat again.


PepeTheFrog wrote:
I'm guessing ANA 777-9 with just under 300 seats will have worse CASM than Air Caraïbes A350-1000 with 429 seats.

Hence I don't understand the point of comparing CASM when airlines operate different cabin setups.



You are right. They should compare with similar cabin layout.


lazyme wrote:
What is the estimated cruising altitude for the 777-X for different weights ?


Great question. It was stated here on a.net that B777-300ER at MTOW has low initial cruise altitude.
The wing is not only longer. It may be slimmer as well. So a higher OEW may well be justified. I believe the new narrow-bodies also gained weight.

I always thought the engine decides the fate of a plane.
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 10:53 am

The big advantage for the A350 1000 is not the 1000 but the 900 and the production of 8-10 per month.

I would be surprised if 779 now when 778 is more or less still born, can reachmore then 3-5 per month.

The cost of producing the 350 should be lower special considering the major investment the 777x represent because of the numbers of production.
 
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 11:02 am

AECM wrote:
I think that in certain companies the B779 extra cabin volume will be used more has 4 a class layout with First and the A35K has a 3 class layout without First


I agree with you, and in such cases the cost per seat on the A350 will be lower. However that does not explain the revenue per seat, and return on investment. Airlines ordering the 77X with that intention are doing so based upon the opportunity to generate additional revenue.

As there isn’t much difference in fuel between the A350 and 77X, and if they are configured with similar number of seats the operating cost difference will come down to the additional crew required for the 77X (more doors), and 10% higher certified mass (therefore higher navigation, landing, and terminal fees).

The NPV models make underlying assumptions on global traffic growth, something which has not been following the rules this year, both passenger and freight airlines have a lot of aircraft parked. I think every operator that has A350s and 77Xs on order are trying to delay delivery.

I am still not very clear on exactly how many confirmed 77X orders there are, many on the books were still unconfirmed. Airlines had paid deposits however still had the opportunity to cancel, as witnessed last year when EK went from 39 A380, 150 + 40 options 77X plus 6 77W to 0 A380, 126 77X, 0 77W, and 50 A359, a significant shift towards smaller aircraft.
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 11:55 am

zeke wrote:

As there isn’t much difference in fuel between the A350 and 77X, and if they are configured with similar number of seats the operating cost difference will come down to the additional crew required for the 77X (more doors), and 10% higher certified mass (therefore higher navigation, landing, and terminal fees).

If configured with a similar number of seats the operator will probably be plugging the extra set of doors on the 777X leaving it with the same number of exits as the A350-1000. The cost difference will just come down to fees.

Even without the plug the extra set of doors would really only pose additional crew requirements thus costs if the airline only operates with the bare minimum crew required for the A350-1000, which I suspect most A350-1000/777X operators don’t/won’t do for service and union reasons.
 
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 1:19 pm

morrisond wrote:
mjoelnir wrote:
astuteman wrote:

I think I may have a plausible explanation for that 1-2% trend.
In the ACAPs Airbus use a density for their fuel of 0.785kg/l whereas Boeing use 0.8kg/l - 2% more dense than Airbus.
Hence if you equalise the fuel density between the two (doesn't matter which way you do it) for a given range the Airbus will lose a payload capability equal to 2% of the fuel load at that range, compared to the range/payload chart figures.
As the 787 and A359 are typically taking c. 100t of fuel on very long haul flights, that would equate to a 2t payload penalty for the A350-900 compared to the ACAP.

Other than that, I think the charts are pretty representative.

There is no huge gulf in plausibility such as that promulgated by one particular member with too many "m's" in his username....

Rgds


Fuel burn is according to weight not volume. You burn kilogram of fuel not cubic meter.

The only place were fuel density intrudes is in regards to max fuel in regards to volume. There the difference should be the other way round, Boeing expecting to fit more kg fuel in the same volume.


Interesting I didn't know modern aircraft could instantly calculate the weight of Fuel spewing through the nozzles and adjust accordingly.

What kind of system do they use to do that?


Stick a lambda sensor into the exhaust and measure airflow into the core, work your way back to weight/volume with the data from the fuel flow meter.

Best regards
Thomas
....the 15 within a couple of days is going to be down to close to zero
 
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 2:10 pm

Matt6461 wrote:
Bjorn Fehrme at Leeham posted analysis a few years ago behind the Leeham paywall. 777-9 was more efficient than A35K on both fuel and direct operating cost. He used a standard seating layout to make it an apples-apples comparison.

IIRC the fuel difference was such that it would disappear absent the GE9X's SFC edge over the TXWB - 4% or so per seat. The overall economic (DOC) edge would still have resided with the 777-9 per seat, however, due to economies of scale on flight crew, en route fees, acquisition cost, and engine mx.


Leeham wrote:
The maximum range and per seat costs of the 777-9 and A350-1000 are close when compared apples to apples.
The advantage for the 777-9 at full aircraft disappears quickly as load factors decline.
If the needed capacity of the long-haul US routes declines, the 777-9 can be too much aircraft for the Gulf carriers


https://leehamnews.com/2018/05/17/boein ... -carriers/

Also:
Per seat fuel burn: -1.5%
Per seat DoC: -1.2 ~ 1.5%
Aircraft trip cost: +11%
Seats per aircraft: 45 (+12%)
That's for a 7000+nm mission, should be close to the best case for the 779.

Best regards
Thomas
....the 15 within a couple of days is going to be down to close to zero
 
sabby
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 2:39 pm

Matt6461 wrote:
sabby wrote:
Revelation wrote:
I think that's pretty noteworthy.

I posted about the overlap between current A350 customers and future 77x customers earlier.

We're told to trust that airlines have more accurate modeling than our back of the napkin scribbles, yet those airlines who would have every reason to just add more A350s are also taking 779s.

We will be told this is just posturing, but getting an order on the books implies a lot of work on behalf of the airlines and a financial commitment that is difficult to erase as well.

Apparently the airlines see value in 779 that people here can't seem to understand.


It is quite telling that all the airlines who ordered the 777-9 operate F. Even if a widebody airliner had the CASM of A321/Max200, they won't be chosen if they are unable to carry the number of high revenue seats airlines desire. If you look at the current long haul 77W configs of those airlines, except the ME airlines, all of them seat < 300, some even < 250. They need the additional space of 777-9. This does not mean 777-9 will have better/worse CASM, but I think CASM was probably the last requirement for choosing 777-9 over A35K (ok, maybe except EK).


On an apples-apples comparison, do you think the 779 has **higher** CASM compared to narrow bodies?

If you're going by nominal seats in average configurations, sure, but that's a willfully blind comparison.

Airlines could absolutely put F in NB's; it just doesn't make sense at NB segment lengths.


I think there's a misunderstanding here - I didn't say airlines can't/won't choose to put F in narrow bodies, I meant if a 737/A321 could do 15 hours flight at their current cost, those airlines would still use the 787/A350/777 for the missions as otherwise they would be leaving a lot of revenue behind. Most of them operate from slot restricted airports so multiple frequencies wouldn't help much and probably wouldn't make sense at that size or stage length for cost. 777-9 is simply a bit bigger than A350-1000 and that difference will be filled by F seats and/or additional J seats. The airlines that ordered 777-9 all have premium heavy configurations.
Onto your question of whether I think 779 has higher CASM, I simply have no idea as we don't have the data yet. We'll have to wait till multiple airlines fly that aircraft.
 
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 2:54 pm

tommy1808 wrote:
Matt6461 wrote:
Bjorn Fehrme at Leeham posted analysis a few years ago behind the Leeham paywall. 777-9 was more efficient than A35K on both fuel and direct operating cost. He used a standard seating layout to make it an apples-apples comparison.

IIRC the fuel difference was such that it would disappear absent the GE9X's SFC edge over the TXWB - 4% or so per seat. The overall economic (DOC) edge would still have resided with the 777-9 per seat, however, due to economies of scale on flight crew, en route fees, acquisition cost, and engine mx.


Leeham wrote:
The maximum range and per seat costs of the 777-9 and A350-1000 are close when compared apples to apples.
The advantage for the 777-9 at full aircraft disappears quickly as load factors decline.
If the needed capacity of the long-haul US routes declines, the 777-9 can be too much aircraft for the Gulf carriers


https://leehamnews.com/2018/05/17/boein ... -carriers/

Also:
Per seat fuel burn: -1.5%
Per seat DoC: -1.2 ~ 1.5%
Aircraft trip cost: +11%
Seats per aircraft: 45 (+12%)
That's for a 7000+nm mission, should be close to the best case for the 779.

Best regards
Thomas


I think the 777X could do better than the above.

As I pointed out above - what isn't new on the 777X? People keep thinking this is a 777W with a new Wing and engines - but almost everything except for the shape of the nose and outer diameter of the Fuselage will be new. It will still be bleed air vs more electric however almost everything else will be an evolution of the 787.

They could do a lot better on weight than people are expecting. This is essentially an 787+ with 5 more years of design time in an 777 Wrapper.

Guy Norris had the OEW weight at 181T in 2018.
 
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 3:15 pm

morrisond wrote:
Guy Norris had the OEW weight at 181T in 2018.


That is still 20% more aircraft to haul around for 12% more seats.

Best regards
Thomas
....the 15 within a couple of days is going to be down to close to zero
 
StTim
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 3:19 pm

morrisond wrote:
tommy1808 wrote:
Matt6461 wrote:
Bjorn Fehrme at Leeham posted analysis a few years ago behind the Leeham paywall. 777-9 was more efficient than A35K on both fuel and direct operating cost. He used a standard seating layout to make it an apples-apples comparison.

IIRC the fuel difference was such that it would disappear absent the GE9X's SFC edge over the TXWB - 4% or so per seat. The overall economic (DOC) edge would still have resided with the 777-9 per seat, however, due to economies of scale on flight crew, en route fees, acquisition cost, and engine mx.


Leeham wrote:
The maximum range and per seat costs of the 777-9 and A350-1000 are close when compared apples to apples.
The advantage for the 777-9 at full aircraft disappears quickly as load factors decline.
If the needed capacity of the long-haul US routes declines, the 777-9 can be too much aircraft for the Gulf carriers


https://leehamnews.com/2018/05/17/boein ... -carriers/

Also:
Per seat fuel burn: -1.5%
Per seat DoC: -1.2 ~ 1.5%
Aircraft trip cost: +11%
Seats per aircraft: 45 (+12%)
That's for a 7000+nm mission, should be close to the best case for the 779.

Best regards
Thomas


I think the 777X could do better than the above.

As I pointed out above - what isn't new on the 777X? People keep thinking this is a 777W with a new Wing and engines - but almost everything except for the shape of the nose and outer diameter of the Fuselage will be new. It will still be bleed air vs more electric however almost everything else will be an evolution of the 787.

They could do a lot better on weight than people are expecting. This is essentially an 787+ with 5 more years of design time in an 777 Wrapper.

Guy Norris had the OEW weight at 181T in 2018.


You think Leeham ignored those items in their analysis?

This is bar the weight assumption. In general early copies are notoriously overweight on most frames. As this is mostly a stretch then perhaps there is more chance it will not be at bit flabby at birth.
 
Opus99
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 3:33 pm

tommy1808 wrote:
morrisond wrote:
Guy Norris had the OEW weight at 181T in 2018.


That is still 20% more aircraft to haul around for 12% more seats.

Best regards
Thomas

20% more than what?
 
mig17
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 3:56 pm

Opus99 wrote:
tommy1808 wrote:
morrisond wrote:
Guy Norris had the OEW weight at 181T in 2018.


That is still 20% more aircraft to haul around for 12% more seats.

Best regards
Thomas

20% more than what?


Than the A350-1000. Almost everyone here, me included are comparing A35K with 777-9. It is even in the title of the thread. And I think this thread could have ended on Zeke long post of yesterday :
Until we have other info (and by the way, even if Zeke is not "telling", I bet he has more info from Cathay ordering both) on the 777-9, the comparison is that the 777-9 is larger, heavier, more expansive to buy and to fly but without better payload/range capability.
Zeke summurized it, the 777-9 is "only OK" if you fit more prenium product and manage to fill it in order to generate more income per day for 20 years, ...

Two other comparison come to mind :
- the A35K is to the 777-9 what the A359 is to the 781
- or more older, the A35K is to the 777-9 what the 77W was to the A380.

And to me, the second one is so accurate because in a way it seem that the 777-9 is the selected replacement of all A380 carrier who want to keep that kind of small fleet of large premium aircraft in the same proportion than the A380.

All the current customer paid "launching" prices but the 777-9 is suffering against smaller frames and in truth, not only the A35K, but more from the A339, the A359 and the 789, less expensive to buy and operate because despite it size, it isn't really more efficient if full and is surely less efficient if not full ...
Last edited by mig17 on Fri Feb 21, 2020 4:08 pm, edited 1 time in total.
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ElroyJetson
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 4:06 pm

The Leeham analysis is interesting. Essentially Leeham is stating the 779 is more efficient than the 35K on both fuel and direct operating cost. This is attributed primarily to improved engine SFC of about 4% over the 35K.

However, this advantage quickly drops with decreased load factor. This is exactly what I would have assumed and directly contradicts our many Airbus fans in this thread.

Based on everything I have read the 779 will carry significantly more payload than the 35K. That makes perfect sense as the 779 has an 11% larger wing and more powerful engines. As always with a larger aircraft the question is can you fill it consistantly? For an airline like EK it seems like a perfect fit.

I certainly think the 779 will have its place and perform at or better than expectations. The 77W certainly greatly exceeded expectations and as a result dominated the wide body market for two decades. As a derivative i do not think the 779 will change the world, but I also do not agree with the many posters who deride it with no data. I intend to keep an open mind and see how it actually performs in the real world.
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tommy1808
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 4:12 pm

ElroyJetson wrote:
Based on everything I have read the 779 will carry significantly more payload than the 35K. That makes perfect sense as the 779 has an 11% larger wing and more powerful engines.


Those 11% need to lift 30t more before you even get to payload.

Best regards
Thomas
....the 15 within a couple of days is going to be down to close to zero
 
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ElroyJetson
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 4:15 pm

mig17 wrote:
Opus99 wrote:
tommy1808 wrote:

That is still 20% more aircraft to haul around for 12% more seats.

Best regards
Thomas

20% more than what?


Than the A350-1000. Almost everyone here, me included are comparing A35K with 777-9. It is even in the title of the thread. And I think this thread could have ended on Zeke long post of yesterday :
Until we have other info (and by the way, even if Zeke is not "telling", I bet he has more info from Cathay ordering both) on the 777-9, the comparison is that the 777-9 is larger, heavier, more expansive to buy and to fly but without better payload/range capability.
Zeke summurized it, the 777-9 is "only OK" if you fit more prenium product and manage to fill it in order to generate more income per day for 20 years, ...

Two other comparison come to mind :
- the A35K is to the 777-9 what the A359 is to the 781
- or more older, the A35K is to the 777-9 what the 77W was to the A380.

And to me, the second one is so accurate because in a way it seem that the 777-9 is the selected replacement of all A380 carrier who want to keep that kind of small fleet of large premium aircraft in the same proportion than the A380.

All the current customer paid "launching" prices but the 777-9 is suffering against smaller frames and in truth, not only the A35K, but more from the A339, the A359 and the 789, less expensive to buy and operate because it despite it size, it isn't really more efficient if full and is surely less efficient if not full ...



The assumption you and Zeke are making that the 779 does not have a payload advantage over the 35K is not based on fact. As a number of posters have mentioned, a number of top tier airliners have ordered both. Perhaps that should give you pause?

Many airlines have ordered both the A359 and 787. Real world data has confirmed within their respective roles both are excellent aircraft. If you choose to believe the 779 is inferior based on zero data that is certainly your right, but it does not add credibility to your opinion.
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ElroyJetson
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 4:22 pm

tommy1808 wrote:
ElroyJetson wrote:
Based on everything I have read the 779 will carry significantly more payload than the 35K. That makes perfect sense as the 779 has an 11% larger wing and more powerful engines.


Those 11% need to lift 30t more before you even get to payload.

Best regards
Thomas



Fair point. The listed payload for the 779 is 162,000 lbs. It will be interesting to see if it meets or exceeds that number once the real world data comes in. The 35K was initially listed as having 150,000 payload capability. Once in service and tweaks were done it modestly exceeded this number. But I guess only Airbus planes exceed expectations. :).

Again, I'll wait to see what the numbers say.
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zeke
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 4:25 pm

ElroyJetson wrote:
Based on everything I have read the 779 will carry significantly more payload than the 35K. That makes perfect sense as the 779 has an 11% larger wing and more powerful engines. As always with a larger aircraft the question is can you fill it consistantly? For an airline like EK it seems like a perfect fit.


Using the OEW of 400,000 lb by Guy Norris above, and the published MZFW in the ACAPS of 562,000 lb, gives a maximum structural payload below today’s A350-1000 that is already in service.

The 77X only has 8klb more thrust a side, that’s not a lot of thrust for the additional 72,000 lb of weight at MTOW.
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ElroyJetson
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 4:45 pm

zeke wrote:
ElroyJetson wrote:
Based on everything I have read the 779 will carry significantly more payload than the 35K. That makes perfect sense as the 779 has an 11% larger wing and more powerful engines. As always with a larger aircraft the question is can you fill it consistantly? For an airline like EK it seems like a perfect fit.


Using the OEW of 400,000 lb by Guy Norris above, and the published MZFW in the ACAPS of 562,000 lb, gives a maximum structural payload below today’s A350-1000 that is already in service.

The 77X only has 8klb more thrust a side, that’s not a lot of thrust for the additional 72,000 lb of weight at MTOW.


With a much larger wing. You failed to mention that. It is the combination of greater thrust with an 11% larger wing. The A359 has a larger wing than the 789 with virtually identical engines in terms of thrust. As you know, the A359 has significantly more payload capability for that reason even though it is a much heavier aircraft.

Zeke, it is certainly possible Boeing screwed the pooch and the 779 is a dog. If so, I have no problem stating that. But as I keep saying, let's wait for the data. You and pinkmachine provided a lot of real world data on the 789 and the 359. I thought it was great, and let me understand how each plane does in real world. That is alli am saying.

Thanks.
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mig17
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Re: 777X vs A350 CASM

Fri Feb 21, 2020 5:01 pm

ElroyJetson wrote:
The assumption you and Zeke are making that the 779 does not have a payload advantage over the 35K is not based on fact.


With no MTOW increase, or no surprisingly low DOW, no the 777-9 will not have better payload / range capability than the A35K. Fact is that the 779 is heavier than previous 77W it is based on but with the same already max out MTOW.
Fact : it is MZFW limited for max payload and MTOW limited on range.

ElroyJetson wrote:
As a number of posters have mentioned, a number of top tier airliners have ordered both. Perhaps that should give you pause?Many airlines have ordered both the A359 and 787. Real world data has confirmed within their respective roles both are excellent aircraft. If you choose to believe the 779 is inferior based on zero data that is certainly your right, but it does not add credibility to your opinion.

The same top tier airlines that are using small fleet of A380 for heavy premium and large fleet of 77W as workhorse.
We have data, maybe not up to date but official : 779 design range for standard config, MTOW, MZFW, ... We also have data on the 77W like OEW that can be extrapolate.
And to come back to your top tier comment, the number of 777-X customer is pretty low and the largest order just went down in favor of A359 ...
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