New Boeing 777X likely to be a highly efficient derivative

Since announcing at this June’s Paris Air Show a 4,000 lbs of increase in engine thrust of the Rolls-Royce Trent XWB engine powering the largest aircraft variant in the Airbus A350 XWB (Extra Wide Body) aircraft family, which enables the A350-1000’s range to increase by 400 nautical miles (nm) or carry 4.5 tonnes of additional payload over the same distance, as well as an increase of 10 tonnes in the aircraft’s maximum take-off weight (MTOW) from 298 tonnes to 308 tonnes, the A350-1000 has faced criticisms, including vocal ones from Middle-Eastern carriers Emirates Airline and Qatar Airways over the 2-year delay in the aircraft’s entry into service (EIS) from 2015 to 2017, in addition to the seemingly insufficient improvement on the variant’s payload/range capability (“A350 delay boosts 777 market appeal“, 20th Jun, 11).

Across the Atlantic, media headlines have focused on the Chicago-based aircraft manufacturer Boeing’s announcement of its re-engined narrowbody 737 MAX that promises a 10%-12% cut in fuel burn per seat over the existing 737 NG (Next-Generation) aircraft and a 4% better fuel burn per seat than the competing tremendously popular arch-rival A320 neo (new engine option) (“Boeing 737 MAX press conference highlights“, 31st Aug, 11).

While the world’s second-largest airframer is still finalising the 737 MAX’s detailed configuration and its engine fan size which has now been narrowed down to the 66-inch or 68-inch CFM International Leap-1B engine (“Boeing 737 MAX to help recover sales momentum“, 5th Sep, 11), initial details have started to emerge on what would become Boeing’s next large widebody product offering which is often dubbed as the “big twin” in the global aerospace industry.

Image Courtesy of Royal S. King

Aspire Aviation‘s multiple sources say Boeing is now eyeing a provisional date of launch in 2013 with an entry into service (EIS) in 2019 for a major 777 revamp, designated as the 777-8X/9X at this stage, with the -8X and -9X being the revamped versions of the ultra long-range 777-200LR and the popular 777-300ER variants, respectively.

In doing so, Boeing will very likely be able to extend its market leadership in the 300 to 400 seat segment in light of the potential threats arising from the Airbus A350 XWB family and continue to maintain strong sales on its lucrative 777 programme, particularly on the 365-seat 777-300ER and the 777F freighter. With a revamped 777, the profit margin on the company’s cash-cow could further be expected to grow with a modest upfront investment in the highly capable derivative aircraft.

The new 777-8X/-9X, sources say, will feature a new derivative engine of the GE90 engine family providing around 100,000 lbs of thrust, a new wing design that is similar to the supercritical wings found on the Boeing 787 Dreamliner and the 747-8 aircraft, as well as the studies currently undertaken by the airframer to feature more composite contents on the revamped widebody to reduce weight.

These combined would enable the 777-9X to deliver a 10%-15% fuel burn saving per seat over the existing 777-300ER contingent upon the aircraft’s finalised configuration which is not expected to take place in the foreseeable future until after the revamped widebody jet is officially launched first.

Engine improvement key focus
The centrepiece of the fuel burn improvement will come from a new engine, with a new General Electric (GE) GE90 derivative being the front-runner. The existing GE90-115B1 engine which provides 115,300 lbs of thrust is already highly efficient, burning 0.25 pounds of fuel per pound of thrust delivered per hour (lb/lbt/hr) whereas the GEnx-2B engine on the 747-8 burns 0.274 lb/lbt/hr. Aspire Aviation‘s sources caution that a direct comparison between the GEnx-2B and GE90-115B1’s fuel burn figures is skewed as the engine fan efficiency normally improves as the fan size increases. The GE90-115B1 has a fan diameter of 135 inches whereas the GEnx-2B engine has a diameter of only 105 inches and the -1B engine has a diameter of only 111 inches. On an equal basis after factoring in the different engine fan sizes, the GEnx-2B engine would be 6.9% more fuel efficient than the GE90-94B engine, these sources say.

With a swathe of new technologies on the GEnx engine that can be incorporated back into the existing GE90-115B1 engine, such as the twin annular pre-mixing swirler II (TAPS II) technology instead of the GE90-115B1’s dual annular combustor (DAC), as well as the composite variable-bleed valve ducts at the exit of the booster stage, coupled with a higher fan efficiency that a larger engine fan size delivers, Boeing is targeting a 10% improvement in the engine’s specific fuel consumption (SFC), the same sources say.

General Electric (GE) declined to comment on the specific fuel consumption (SFC) data on its engine, citing company policy on not to release SFC information on its products, but added “GE and Boeing are closely connected as we study possible improvements to the GE90 engine. We look forward to continuing our working relationship on the Boeing 777 aircraft which has been extremely popular with customers”.

Meanwhile, the 777X programme nevertheless presents an opportunity to the East Hartford, Conneticut-based engine-maker Pratt & Whitney (P&W), as its vice president (VP) in next generation product family, Bob Saia previously commented that there is “no limitation on fan drive gear system” and “with time, we can reach the 100,000 lbs category” (“Special Report: The engine battle heats up“, 10th May, 11) . Its geared turbofan (GTF) engine, already offered on multiple narrowbody applications such as the Bombardier CSeries, Irkut MS-21 and the Airbus A320 neo (new engine option), relies on a gearbox to enable the fan and the turbine blades to rotate at different speeds, thereby maximising engine efficiency and provides a 16% fuel burn saving over the existing engines.

“We believe it is quite possible to scale the PurePower geared turbofan to thrust levels required for widebody applications. We believe the inherent benefits of better fuel burn, CO2 and noise performance could be realised in higher thrust engines,” Pratt & Whitney (P&W) spokeswoman Katy Padgett said.

“Right now we are completely focused on executing our engine programmes for our current four narrowbody applications: the Bombardier CSeries, Mitsubishi Regional Jet (MRJ) Airbus A320 neo family and Irkut MC-21. We have validated the projected fuel burn reduction for the PW1524G engine in ground and flight testing – the 16% projection is estimated compared to a CFM56-5. Its efficiency is greater when compared with other older engines,” Padgett emphasised.

However, given the strong relationship that Boeing and General Electric (GE) have, as observed in the CFM Leap-1B engine exclusivity on the newly-launched 737 MAX programme, Pratt & Whitney will be facing an uphill, if not insurmountable battle to put its GTF offering on the 777X. Aspire Aviation thinks that with a significant fuel burn reduction that a new GE90 derivative engine would have, Boeing will have little incentive to walk away from the engine exclusivity pact with GE on the 777-300ER/-200LR and the 777F freighter and therefore will be very likely to maintain the engine exclusivity on the 777X.

Image Courtesy of General Electric

Stretching & payload/range capabilities
The revamped 777-9X will likely see the seat count on the 777-300ER being increased from 365 seats in a typical 3-class configuration to 380 to 390 passengers, thereby delivering a saving as large as 5% in fuel burn per seat, Aspire Aviation has learned.

While many options are currently being evaluated, including slightly stretching the 777-300ER’s 73.9 metres (m) fuselage to accommodate several additional rows of passengers, another option being studied is “internal stretching” without actually lengthening the 777-9X’s fuselage by removing internal frames in some sections to provide more room to comfortably accommodate 10 seats in a single row.

Aspire Aviation‘s sources say this “internal stretching” would provide more cabin space and seat width to the existing 10-abreast configuration adopted by Emirates Airline on its 777-300ER aircraft without impacting the aircraft’s cross-section nor facilitating the need to stretch the 777-9X’s fuselage, thereby avoiding costly modifications on the revamped version of Boeing’s largest twin-jet.

This would help minimise the research and development (R&D) cost incurred as well as help lessen the demand for engineering resources, at a time when Boeing is developing the 737 MAX with an entry into service (EIS) in 2017 in addition to mulling to develop a 320-seat 787-10X stretch version of its game-changing 787 Dreamliner.

Furthermore, the new 777-9X is very likely to feature a slightly lower maximum take-off weight (MTOW) at 753,000 lbs and modestly improved payload/range capabilities than the 777-300ER, Aspire Aviation has learned. Given the significant weight saving brought by a new composite wing, this level of MTOW would maintain its existing lead over the A350-1000 and potentially undermine the -1000’s business case.

The MTOW of the A350-1000 is often criticised as insufficient and that its payload/range capabilities are marginal to the specifications of the existing 777-300ERs, with the most vocal critics being the chief executives of A350-1000 customers Emirates Airline and Qatar Airways.

“If they had talked to me, I would have said: ‘Not good enough’,” Emirates chief executive Tim Clark told flightglobal.

“I was expecting that Airbus would make a competitor to the 777-300ER, that we would have considerably lower seat-mile costs and at least 15% more range, but that is not going to happen,” Qatar Airways chief executive Akbar Al Baker was quoted in an exclusive interview by flightglobal.

“What they are going to give us is fewer seats than the 777-300ER and marginally more range,” Al Baker lamented.

The A350-1000 has a maximum take-off weight (MTOW) of 308,000 kilograms (kg) (679,000 lbs) whereas the 777-300ER has a MTOW of 351,535 kg (775,000 lbs).

With 380-390 seats, coupled with a combined 10% to 15% fuel burn saving on a per seat basis, the 777-9X’s cash operating cost (COC) would be “on par or even be better” than that offered by the A350-1000 XWB, Aspire Aviation‘s sources at Boeing claim.

Derivative approach
While Boeing is currently not ruling not building a clean-sheet 777 replacement, Aspire Aviation thinks there are major factors at play that will eventually let the Chicago-based airframer to opt for a derivative approach on the 777X.

First and foremost, a derivative 777-8X/9X would feature significant advancements in terms of fuel efficiency and capability for a modest investment. A 10% to 15% fuel burn improvement per seat would be an excellent result for an upfront investment of roughly US$3 billion with the bill for the centrepiece of the fuel burn improvements, the engines, likely to be contributed by the world’s largest engine-maker General Electric (GE) on a derivative engine that will incorporate the latest technologies from the GEnx engine.

Moreover, with a provisional entry into service (EIS) date of 2019, Boeing will be very well-positioned to face the upcoming competition, the A350-1000 which will only enter into service 2 years earlier in 2017. Coupled with a possibly higher maximum take-off weight (MTOW) and better payload/range capabilities, the 777-9X could potentially be more competitive than the A350-1000 in the marketplace.

Secondly, the production system for a composite clean-sheet 777 requires significant investment in facilities and autoclaves, which is risky both from a financial and programme management perspective. After witnessing perennial production hiccups on its supply chain which resulted in 3 years of delays and billions of dollars in cost overruns, the 787 Dreamliner is a painful lesson for Boeing to learn and its latest decision to go down the re-engining route instead of opting for a new small airplane (NSA) whose composite production system does not yet exist is a testament to those painful lessons learned (“787: a dream becoming reality & its roads ahead“, 29th Aug, 11).

Meanwhile, the second-generation out-of-autoclave (OoA) composite technologies such as the “Quickstep” technology developed by Australian aerospace and defence firm Quickstep which utilises a fluid-based heat-transfer curing process that cuts a staggering 43% of time taken during the curing process and results in a higher delamination resistance and a higher fibre-matrix adhesion through “lower initial resin viscosity”, need time to mature and find their way onto widespread commercial aerospace applications.

For instance, the carbon nanotube reinforced polymer (CNRP) material which is used on Lockheed Martin’s F-35 Joint Strike Fighter (JSF) undoubtedly has a bright potential in the commercial aerospace arena. According to a study conducted by MITRE in 2004, a 50% single-walled nanotube (SWNT) CNRP is 17% stronger than the CFRP, yet 30% lighter.

Yet for these 2nd-generation composite technologies to mature before a 2019 entry into service (EIS) of the 777-8X/9X would be utterly unrealistic and insurmountable.

In the meantime, another important factor, if not the most important one, is the timeline for the developments of other derivative programmes. With the 737 MAX entering service in 2017 and the 320-seat 787-10X going to be launched in 2012 at the earliest with an EIS in 2018, adding the 777-8X/-9X with a 2019 EIS to Boeing’s plate could present a task in itself, particularly the track record of execution on both the 787 and 747-8 programmes is not satisfactory, to say the least.

Although the engineering resources required by the 787-10X are minimal and the foundation of stretching the 787-9’s fuselage has already been laid, the engineering resources demanded by a clean-sheet 777 would nonetheless be burdensome to both the 737 MAX, the 787-10X and the 777X developments altogether.

As concerns surrounding the developments of the A350-1000 linger, sales on the existing 777 will continue to stay strong in the next few years and the 110 777 orders received so far this year is a testament to the 777’s strong business case.

Ultimately Boeing has to find a response to the more fuel efficient A350-1000 at some time, however.

“However, it will be challenged when the A350-1000 does come to market. It is our belief that the 777 family will be challenged, so we are going through conducting a widebody study to understand what sort of improvements we will need to bring to market,” Boeing Commercial Airplanes (BCA) vice president (VP) of business development and strategic integration Nicole Piasecki acknowledged during the Deutsche Bank Aviation Conference in New York on 13th September.

“[The 777X’s specification] depends on our customers requirements, that depends on what in fact the A350-1000 turns out to be. And it also depends on the timing requirements of the marketplace and the dynamics between the [new 777] and the [787-10X variant], what sort of investment profile do we want to have and over what period of time and which airplane comes first,” Piasecki added.

With a 777-8X/-9X being 10% to 15% more fuel efficient than the existing 777-200LR and 777-300ER, respectively, Boeing will be able to maintain its market leadership in the 300-400 seat segment with a modest investment. Coupled with a strong established customer base of the 777-300ER, Boeing’s new 777-9X is likely to be popular with the -300ER operators. For the time being, though, eyes on the Wall Street will be closely watching every development as “programme execution” will remain the word of the day.

Trackbacks and pingbacks

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  1. Daniel, this is a great article. Extremely informative and you don't pull any punches. Thanks!

  2. Daniel - Agree with Aurora, except that it is not clear to me what the difference is between tne 777-8X and the -9X. Can you explain?

  3. The 777-8X is supposed to be a 777-200LR revamp and the -9X to be a -300ER revamp, if my Boeing source is correct.

    1. "In doing so, Boeing will very likely be able to extend its market leadership in the 300 to 400 seat segment ..."

      This is true only with the -300ER. The A333, A359 and -1000 monopolize the mkt below 350 seats. According Piasecki, the 789/10 will take on the A333, but that leaves the all-new plastic A359/1000 without competition from a new plane. How B will eventually draw pax line between the 7810 and the smallest 777 revamp is the question. If for example you are right that the -9X will have 380-90 seats (even tho TimClark wants the -300ER to stay at 365 and those numbers would kill the 748i), then maybe it would make sense to enlarge the -200ER to 315 seats to compete more directly with the A359. Piasecki may have been alluding to this issue when she said:

      "And it also depends on the .........dynamics between the [new 777] and the [787-10X variant]"

      Too bad she did not say specifically what those "dynamics" are. But the likely revolve aroundBasically what seems to be happening. The real problem I think is the higher A pushs the A359/1000 in size, the more likely B will be a small player in the 300-350 mkt to the extent that they compete with only re-vamps. Airlines that want a famiuly of planes in that segment might like the 7810 at 320 seats, but not if they also want something bigger below 350 seats. Better to buy a new plastic family.

      1. The 787-10X will be a 320-seater to fly 6,800 nm (nautical miles).

        The 787-10X will have a 10% lower operating cost per seat than the A350-900 & 5% better than the A350-1000, primarily owing to the 787-10X being lighter.

        The 777-200ER currently flies 7,725 nm with 301 passengers.

        For those who don't need the additional range that the A350-900 provides, the 787-10X would be very fuel efficient for a 777-200ER replacement.

  4. Great article, but you should compare fuel burn numbers at cruise instead for takeoff - it could (or should) look different there, as the GEnx should be better at cruise than the GE90-115B. According to an older article in AW the GEnx is 6.9% better than the GE90-94B (,%20Combustor%20Technology). The -115B is somewhat better than the -94B, but I guess that should be in the order of 2-3%.

  5. I just did a quick comparison of engine SFC's here:

  6. Hi Daniel good article. I think the 15% fuel efficiency coming from the engines is unlikely. Radical technology improvements over the GE90_11x probably won't exist. 5-7% Would be great.

    The 'internal stretching" done by EK 777s, 9 abreast A330s, 8 abreast 767s might be a nice PR trick boosting "fuel efficiency per seat", the airlines won't be impressed. A few rows/LD3s extra would be better..

    Without defending the A350-1000XWB I think looking at how many 777-300ER slots are sold around the EIS of the -1000, (0) makes clear what's on the table. While dismissing the -1000 at any opportunity everyone looking at the specs knows the threath is real. While pointed out happely the -1000 order book is low (not so remarkable 6-7 yrs before EIS) everyone knows (or could know) a good percentage of the -900 orders/options will likely be converted to -1000s during the next 5 yrs.

  7. Keesje,

    Please note that the 10%-15% better SFC per seat on an airframe basis, assumes many things:

    1.) a 10% better SFC on a GE90 derivative. After incorporating the GEnx technology, it should have a 7% better fuel burn on the engine. Coupled with other new improvements such as the ceramic matrix composite (CMC) that contributes 1% more SFC reduction, a 10% overall engine SFC reduction should be within reach, if GE does invest heavily in new technologies.

    2.) After installing the the new GE engine onto the airframe, the actual combined fuel burn saving should be reduced to 7% following a 2-3% "installation effect" including weight penalty.

    3.) But the 7% "integrated engine SFC reduction" does not take into account the new 777X composite wing & any fuselage modification. Those new wings & fuselage modifications, coupled with more seats, should produce a 15% better SFC per seat in overall.

    Of course all these are preliminary data from my Boeing source. Much really depends on how the 777X evolves & what Boeing is going to do with the design.

  8. [...] Aspire Aviation today published a long piece about the 777X. See the story here. Update, Sept. 14: Aeroturbopower comments on the fuel burn analysis for the 777X. Advertisement [...] Reply
  9. Flightglobal says: "As part of the studies, Boeing is examining optimising the fuselage around the new larger wing and looking at both a fuselage stretch and a shrink of the 777-300ER. One conceptualisation of the -9X would be an additional stretch to the 777-300ER, while the -8X would be a shrink of the 365-seat jet, The 777-8X and -9X would allow Boeing to span the products between the proposed 330-seat 787-10X and 467-seat 747-8."

    I think stretching bothe the 300 and 200 fuselages would be a smart move, positioning them inbetween the A359 and A3510 and above the A3510.

    Coincidentally I predicted this a year ago.

  10. I do think stretching the 777-200LR would be great, particularly for carriers like Virgin Australia, Qantas and British Airways (BA) to operate Sydney-London non-stop with more payload, against the payload-restricted 777-200LR operations on such a route.

    Although the BA's A380-800HGW (high gross weight) will have such an ability to operate London-Sydney non-stop from end of 2012 onwards, it is still payload-restricted.

    Though the 777-8X shrink, or effectively a revamped 777-200LR, is meant to be a niche anyway.

    Read Jon's very great article here:

  11. hi daniel

    great piece

    may i add the potential of the 777 attic space for utilization. at the most extreme, boeing can reposition the cockpit into the attic space to gain maybe 3 rows for first or business class seats. it will also give the 777 pilot a 747 kind of high view.

    please visit my blog at

    keep it up. thanks

  12. Hi Rengab,

    Really thanks for the encouragement. I will definitely keep up the good work, along with my teammates in the Aspire Aviation Team.


  13. [...] at the same time freeing up financial and engineering resources for a potential 777 revamp (“New Boeing 777X to be a highly efficient derivative“, 14th Sep, [...] Reply
  14. [...] double-stretched 787-10X as well as an upgraded 777-8X and 777-9X by the end of the decade (“New Boeing 777X likely to be a highly efficient derivative“, 14th Sep, 11). This makes a smooth execution on the 737 MAX all the more important to [...] Reply
  15. [...] seats would push the fuel burn per seat reductions to 10-15% versus the 777-300ER (“New Boeing 777X likely to be a highly efficient derivative”, 14th Sep, 11). Additionally, increased usage of composites, and/or aluminum-lithium (Al-Li) [...] Reply
  16. [...] and 2013, respectively, with respective entry into service (EIS) dates in 2018 and 2019 (“New Boeing 777X likely to be a highly efficient derivative“, 14th Sep, [...] Reply
  17. [...] commented, while adding the oneworld member is interested in the revamped 777X as well (“New Boeing 777X likely to be a highly efficient derivative“, 14th Sep, [...] Reply
  18. [...] likely to strengthen Boeing’s leadership position in the 350-400 seat market segment (“New Boeing 777X likely to be a highly efficient derivative“, 14th Sep, [...] Reply
  19. [...] previously reported entry into service (EIS) date of 2019 and a programme launch of 2013 (“New Boeing 777X likely to be a highly efficient derivative“, 14th Sep, 11), and is the latest indication that the development of the revamped 777 is [...] Reply
  20. [...] advertises its A350-1000 as being 25% more fuel efficient per seat than the 777-300ER (“Boeing 777X likely to be highly efficient derivative“, 14th Sep, [...] Reply

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