With the 777X remained in Everett, Washington (thanks to both Richard Aboulafia and Saj Ahmad to know about the real benefits of the 777X (and subsequently of the 737 MAX) being built in Washington State to state’s Economy and about the risk factor of 777X), is now time to make a fact-check on the growing competition on 777X vs A350-1000. The Aspire Aviation has a story about the 777X improvements after the news of the order of Cathay Pacific for 21 Boeing 777-9X: http://www.aspireaviation.com/2014/01/01/boeing-777x-ultra-long-haul-leader/
The story starts to talking about the technical facts of the 777X and A350-1000 engine, one against one:
The centrepiece of the revamp that drives the 400-seat 777-9X to have a 20% lower block fuel burn per seat than the 368-seat 777-300ER and a 15% lower cash operating cost (COC) per seat, as well as a 12% per-seat fuel burn and 10% COC per seat advantages against a 344-seat A350-1000, is the 132-inch General Electric GE9X engine that cuts its engine specific fuel consumption (SFC) by 10%.
The GE9X engine will sport 16 fourth-generation composite blades, 2 and 6 blades fewer than the GEnx and GE90-115B engines, respectively, in addition to a 61:1 overall pressure ratio (OPR), 27:1 pressure ratio, a 3rd-generation twin-annual pre-mixing swirler (TAPS III) utilising ceramic matrix composite (CMC) that requires 20% less cooling and is at 1/3 the weight, yet at double strength than conventional materials.
These combined will make the GE9X having a SFC advantage of 5% or more against the Rolls-Royce Trent XWB-97 onboard the Airbus A350-1000, which only has a 52:1 overall pressure ratio (OPR) and a 118-inch engine fan size.
This prompts Derby, United Kingdom-based engine-maker Rolls-Royce to claim that its Trent XWB engine is the only turbofan that is “validated” and that a bigger engine fan size creates more drag and weight, which in turn requires more thrust and carries a fuel penalty in the end.
“The situation today is that the Trent XWB has completed its ground tests and is well advanced in its flight testing regime on the A350 XWB. Only two parties that have the complete data on how both the aircraft and engine are performing – Airbus and Rolls-Royce. And while neither party, naturally, would share all the data, there is a very clear message coming from the test programme: The Trent XWB is the most efficient engine flying in the world today and is on target to meet its specifications at entry into service next year,” Rolls-Royce spokesman Bill O’Sullivan insists.
“One key difference, of course, is that the Trent XWB is delivering its performance now and the GE9X is aiming to achieve a performance level at entry into service, which now appears to be stated as 2020. In terms of measuring performance and fan size big does not always equal best – its about delivering the optimum engine for a given application, so the engine is right-sized for the aircraft’s specific mission requirement. And ‘big’ comes with significant drag and weight both of which translate into fuel burn penalties,” O’ Sullivan adds.
However, while it is true that the Rolls-Royce Trent XWB is poised to become the most fuel-efficient turbofan when the A350-900 enters into service in early-September 2014 (“Boeing’s widebody dominance hinges on 777X success“, 24th Oct, 13), Rolls-Royce’s claims appear somewhat vague, as a 1-inch increase in fan size usually leads to a 0.5% reduction in specific fuel consumption (SFC). Given the GE9X is 14 inches bigger in fan size than the Trent XWB-97, a 5% SFC advantage makes sense even after accounting for the drag and weight penalty.
Next, the GE9X features ceramic matrix composite (CMC) that is 20 years in development and is likely to usher in a new level of thermal efficiency since the CMC is able to withstand an operational temperature as high as 2,400°F (1,316°C), which is unlikely to be matched by the Trent XWB-97 engine, although Rolls-Royce’s study into a RB3039 engine featuring composite fan blades could theoretically negate some of GE9X’s advantages by the end of the decade.
Most importantly, any claims saying the GE9X engine is “oversized” overlooks the fact that the 777-9X is a considerably larger airplane than the A350-1000 and as such, the airframe-engine combination needs to be looked at in a proper perspective and is likely to be optimised. For example, the 777-9X is 76.48m (250.11ft) long and its wing has a 71.1m (233.4ft) wingspan, compared to the A350-1000′s 73.78m fuselage length and 64.75m wingspan. – Aspire Aviation
Despite of being more larger and taller than the Trent XWB, the GE9X has a larger compressure pression ratio (27:1), and contributing for a total pressure ratio of 60:1, and, the fact is the GE9X is larger due to that largest pressure ratio, and that improves efficiency. The Trent XWB-97 is also based on a older architecture than GE9X: The RB211, who also has revolutionated the aviation, had the early problems with carbon fiber fan blades, on the manufacturing, then used a more heavier titanium fan blades, and those delays on RB211 trounced Lockheed L-1011 in 1970s, favouring the McDonnell Douglas DC-10 (who had only GE CF6 and Pratt & Whitney JT9D), and the RB211, and his variants, used/uses conventional methods of manufacturing which makes the engines more heavier. The GE9X was based on GE90, a completely new engine at the time of launch. The use of CMCs also increases resistancy and lowers the weight, while using additive manufacturing process, which also reduces maintenance costs. The RB3039 project, also forgets the number of the blades of the engine, the use of CMCs and the maintenance costs, and how forgotten the use of 3D printing for engine parts and the impact of that. The 777X may be heavier and larger than A350-1000, but has lower costs for operation.
So, the AviationFact’s Truth-O-Meter says about this statement: Mostly False.
Now, here it is an image of the weight comparison of the 777X vs A350-1000.
How Airbus distorted the older difference between size and weight. An engine being larger, isn’t meaning of being heavier. Based on the backward statement, the engine of the 777X will be more lighter, and Airbus also denied of the fact of the 777X wing being in CFRP, which cuts weight to the plane. Staying only the Aluminium fuselage being heavier due to stretch. But will be better than a CFRP panel fuselage, during an eventual repair. The Folding wingtip also helps the 777X being more efficient and accessible to narrower gates and smaller airports, using the raked wingtips, to be an Code F airliner on a 45m (Code E standard) runway and Code E outside. More larger a wing is, better will be the performance on air, and also the fuel efficient.
In this case, the rating of the AviationFact’s Truth-O-Meter about the claims of the graphic: False.
And about the practical use of the 777-8X:
Together with the 9,300nm ultra long-haul 777-8X that is capable of hauling 17 more tonnes of cargo when deployed on the same mission as the 344-seat A350-1000 while having a 5% lower block fuel burn per seat, or flying sectors that its competitor cannot, it would be safe to assume Boeing believes the 777X will be the ultra long-haul leader in the future.
The 777-8X has earned 70% of the replacement market of the 777-200LR and also be praised to carry the same passenger count of the A350-1000 and 777-300ER using the same range of the 777-200LR, Etihad ordered 9 777-8X and Emirates ordered 35 777-8X replacing some of the 777-200LRs. In fact, the 777-8X will be, without no bias, the ULR leader, with those facts.
So, the AviationFact’s Truth-O-Meter has the rating to this statement of: True.
The reverse holds true in terms of seat width, as Airbus launched a futile 18-inch seat width campaign for long-haul travel that backfired from airlines, despite the clear industry trend that the 10-abreast configuration is becoming increasingly commonplace accounting for 69% of all 777-300ER deliveries in 2012, up from 46% in 2011 and 15% in 2010
In fact the Airbus campaign for larger 18-inch seat was only an “carnival barker” to distract from the real issues, and for this fact, Lufthansa negated support for an project similar to that:
“It is completely an issue for airlines. We want to be able to address our markets in the way we are best positioned in each segment,” Lufthansa executive vice president (EVP) Nicolas Bucholz commented.
And other airlines, did the same. In fact, the 69% figure for 10-abreast 777 is true, for that fact, Boeing redesigned walls of the 777X to be more comfortable at 10-abreast, likewise the A350 is at 9-Abreast. The campaign failed due to that fact and Airbus doesn’t want to admit their defeat. Airbus also forgot to announce publicly the plan of making 11-Abreast economy seats for the A380, which would be smaller than 18-inch, probably at 16.5-inch.
So, for this statement, AviationFact’s Truth-O-Meter says: Mostly True.
So, this is the claims and also the confirmation, or even negation of the claims, explained with facts. This is fair. Happy new Year 2014!!