Given that the A350-1000 and the 777-300ER are being increasingly compared in the market place I thought it might be interesting to debate the comparative merits of both platforms. I know that data about the 350 is scarce since it's not a fully defined aircraft but it should be interesting discussion in any case.

Some Baseline data from Boeing and Airbus

A350-1000 777-300ER
Pax 350 365
Length 242'10" 242'4"
Cabin Width 18'4 19'3
Range 8000nm 7930nm
Fuel Capacity 41,215 gal 47,890 gal
Cargo 10P + 12 LD3 8P + 20 LD3

Bulk Cargo 400 cu ft 600cu ft
MTOW 657,000lbs 775,000lbs
MZFW 470,700lbs 524,000lbs

Unfortunately OEW listed as n/a for the A350 on Airbus's website.

Cathay Pacific quoting and unnamed source from Airbus ( http://cathaypacific1946.blogspot.com/sear...p;max-results=7 ) claims that the 350-1000 will burn 25% less fuel than the 300ER.

For comparison purposes lets assume that both aircraft burn their entire fuel capacity to achieve their claimed range. This isn't true I know but it should yield a worthwhile comparison. Thus we have the -1000 burning 5.152 gal per mile and the 300ER at 6.039 which yields about a 15% advantage to the -1000 well off the 25% claimed. If we look at it on a per passenger basis (an equalizing the ranges at 8000 to make the math simple) the 300ER burns 131.205 gal/pax and the -1000 117.757 which diminishes the -1000's advantage to around 11%

The other interesting question is how cargo affects the picture. It seems clear from the data above that the 300ER enjoys a decided advantage in under floor cargo capacity which would further offset that 11% advantage. And if the -1000 comes in overweight its advantage will be further eroded.

However given that the 350 is going to be an all composite aircraft representing the latest and greatest technology it should enjoy an additional advantage in maintenance costs that is very difficult to quantify at this point. We can however reasonably assume that it will not be as great an advantage as the 787 is claiming due to the panel construction (vs. barrel) and reliance on old style bleed air for pressurization and the like.

At this point one has to begin wondering what Boeing can do in the way of improvements to the 777 line. APB is talking about winglets for the 777 which generally have yielded 5-7% though this may be less because the 300ER already features raked wingtips. GE can probably apply some GenX technology to the GE-90 which might yield another 1-2%. Application of composites and other new technologies could probably lighten the aircraft and yield some improvements. Given what Boeing has been able to accomplish with other aircraft something in the range of a 7% improvement in DOC's seems feasible which would erode the 350's advantage to only 4% on a per passenger basis and even less when cargo revenue is considered. And if the -1000 comes in overweight and below spec it could well turn out that a 300ERX might well have an advantage.

Looking forward to the discussion.

It's really hard to determine since all Airbus can offer right now is "guaranteed guestimates" - in other words, what they expect the worst-case scenario to be.

EK has said that the data they have been shown for the A350-1000 will result in a plane that will not fly quite as far as their 777-300ERs currently do and will carry six tons less payload for flying as far as they do. This might be why they have only committed to 20 for the time being and keep pushing Boeing to try and shrink the fuel burn delta to the A350-1000 by 10%.

Now, I imagine the fuel delta is greater then 10%, but in EK's case, it might be that 10% better fuel burn is enough when combined with the greater payload and operating range to keep operating the 777-300ER going forward.

Just curious if you have a source for EK's comments?

Only thing is, Airbus got into the rather unhealthy habit of skewing that a little too much toward the BEST-case scenario for their widebodies throughout the early part of the decade.... and look where that left the A345/A346.

Clicky

Well it might be why Airbus didn't complete firm-configuration for the A350-900 this month as planned. They probably continue to tweak the numbers. I mean even if they are good, if Airbus thinks they can make them better, waiting a bit might not be a bad idea.

It’s nice to see that my back of the envelope calculation yielded the same 11% that EK is reporting. The interesting question now becomes what is 6000kg of cargo worth? I have no idea what kind of rates Emirates gets for cargo (does anyone out there know?) but I'd be willing to be that the revenue from 6000kg (or 13,227lbs) will more than offset the additional fuel burn of the 300ER.

Which brings us back to the questions of what Boeing can achieve with a 300ERX and the status of the 350 program? If a fully loaded 300ER is already a more profitable aircraft than the -1000 then an improved 300ER up against and overweight and underperforming -1000 (and it seems increasingly likely that the -1000 will not live up to the specs Airbus is claiming at this time) could well end up with a decided advantage.

In fairness one must again note that the advantage in maintenance costs that a -1000 will almost certainly enjoy will serve to tilt the scales back towards the Airbus product. Has anyone seen a number quoted as to what the maintenance savings might be worth vs the 777?

Stitch,

I think your statement was tongue-in-cheek. Why delay its freeze date when you already have a good design. You can always spin it by stating that we are continuously looking @ the suite of upcoming technologies for timely improvements etc.

However,

Mr. BOIENG777 blog title, Boeing cites 787 progress as Airbus A350 slips, infers that Airbus is having serious design issues with the 350XWB and that is the reason why for the six or more months delay in its freeze date. However, he doesn’t identify the issue (s). Most likely, there are many. However, I think I can identify the critical one.

1ST,

The ABC of airframe design is ASP, aerodynamic (wing; Aspect Ratio), Structural (MZFW) and engines (SFC) that cumulate into the weight/ range curve.

This curve has two (2) inflexion points,

1. Range (MZFW) @ minimum fuel
2. Range (Payload) @ Maximum fuel

The second point is the stated design parameter.

2nd,

All airplanes fall into one of two catalogues, Fuel or MTOW limited

@ Design range, MTOW – (OEW + Payload + Usable Fuel) = 0

Criteria; If + (Fuel Limited), 0 (Ideal) & - (Weight Limited)

Ideal is when Maximum fuel = Usable fuel

We have all we need to do Ski206 request and identify Mr. Boeing777 unidentified critical issue.

Boeing 777-300ER

It is a know fact that the 300ER is fuel limited as follows,

MTOW: 775,000#
MZFW: 524,000#
OEW: 370,000#
Payload: 154,000# = MZFW – OEW
Usable Fuel: 320,870# (6.7#/G (47,890 Gal)
Payload @ design range (8,000 nm) = 76,650# (210#/P*P (365))

@ Design range, MTOW – (OEW + Payload + Usable Fuel) = 0

775,000 – (370,000 + 76650 + 320,870) = 775,000 – 767,520 = 7480#.

It is less than 1% MTOW fuel based limited. This is why it is such a marvelous airplane.


Airbus 350-1000

MTOW: 657,000#
MZFW: 470,700#
OEW: #?
Payload: #? = MZFW – OEW
Usable Fuel: 276,140# (6.7#/G (41,215 Gal)
Payload @ design range (8,000 nm) = 73,500# (210#/P*P (350))

Since the OEW is not available, assume Ideal

@ Design range, MTOW – (Payload + Usable Fuel) = OEW

657,000 – (73,500 + 276,140) = OEW = 307,360

Payload = MZFW – OEW = 470,700 – 307,360 = 163,340# vs. 154,000# (300ER)

If this was really true, immediately, Boeing & the world shall be running to Airbus to ascertain,” How did you do it?” We know this is NOT true since by its sales and EK and others have stated that -1000 payload is less than the 300ER.

The conclusion is that the -1000 is weight limited, how much?

From Ski206 post,

“Cathay Pacific quoting and unnamed source from Airbus ( http://cathaypacific1946.blogspot.com/sear...p;max-results=7 ) claims that the 350-1000 will burn 25% less fuel than the 300ER.”

Taking it as total fuel trip, not per any parameters (P, W etc)

47,890/1.25 = 38312 Gal or 256,690 # Vs 276,140# maximum fuel capacity

OR

657,000 – (73,500 + 256,690) = OEW = 326810

Payload = MZFW – OEW = 470,700 – 326810 = 143890# vs. 154,000# (300ER)

This appears to be closer to the true. The question is how close? If true, 10,000 # payload difference is really immaterial. The 300ER should be dead, but it is not.

From Mr. Boeing777 post,

EK stated,

“Based on Emirates' mission rules, the A350-1000 will burn 21per cent less trip fuel, and on a seat basis 11 per cent less than the 777-300ER," Jewsbury says.
However, he adds that the 777-300ER can carry another 6000kg of structural payload in the Emirates configuration.”

Using EK numbers,

47,890/1.21 = 39580 Gal or 265,200 Vs 276,140 maximum fuel capacity

Payload = 76,650 – 13,200 (EK adj) = 63,450

OR

657,000 – (63,450 + 265,200) = OEW = 328350

Payload = MZFW – OEW = 470,700 – 328350 = 142350# vs. 154,000# (300ER)

This indicates that the OEW is estimated around 328,000.

Fuel @ 8,000nm & 350 is

657,000 – (73,500 + 328,000) = 657,000 – 401,500 = 255,500 vs. 276,500

Whereas the 300ER is calculated to be 0.97 % (7,480/775,000) MTOW fuel based limited, 1000 is estimated to be 3.3% (21,500/657,000) MTOW weight based limited.

And, this doesn’t take into account any reported (rumored) OEW increases up to 8 tones (17,600#).

This simple analysis indicates that -1000 has a serious underweight condition. A condition it inherited from the 340-600.