If anyone in the industry questioned Boeing's wisdom in basing its next long-range twin on the 777 rather than a bolder, all-new design, any doubts were dispelled at the air show here last week, where the much-anticipated 777X was launched on a $95 billion-plus wave of 259 orders and commitments.

The new twinjets combine an updated version of the otherwise conventional current 777 fuselage with all new General Electric GE9X engines and an all-composite wing. The 777X is not only the heir apparent to the 777-300ER, Boeing's dominant long-haul twin, but it is also the company's challenger to the Airbus A350. And it is Boeing's first attempt to tap the intercontinental market in the 400-plus seat range below the 747-8. Yet, while the 777-8X and -9X bear an outward resemblance to today's big twin, new details unveiled here reveal a different story beneath the skin.

At 250 ft. long, the 777-9X will be exactly the same length as today's 747-8, and 8 ft. longer than the 777-300ER. Configured to carry more than 400 passengers, the aircraft will have a range of more than 8,200 nm, according to Boeing industry officials say the target is likely to be around 8,400 nm. The 777-8X, with capacity for 350 passengers, is sized close to the current 777-300ER and will have a 9,400-nm range. The aircraft will be powered by the GE9X, which will be rated at around 105,000 lb. thrust, confirms David Joyce GE president and CEO.

“It is a step-change in aircraft design and a step-change in propulsion, but we have to wait seven or eight years for this to come,” says Tim Clark, president of Emirates Airlines, which led the launch group at Dubai with orders and commitments for 150 777Xs in addition to options for 50 more. “The -9X will have a 16 to 17 percent delta in fuel burn [compared to the current 777-300ER] and is an aircraft that is redesigned inside and has a new wing. It is all-composite and has great lift over drag. The -8X is about the same size as the 777-300ER but will be able to fly 17 to 18 hours nonstop and with the same fuel efficiency as the -9X,” he adds.

“We are confident in the performance of the aircraft, and we know we are significantly better than the A350-1000,” says 777X Vice President and General Manager Bob Feldmann. Boeing predicts the 777-9X will have 12% better fuel burn than the A350-1000 while the -8X will be 5-6% better. The performance estimates combine the planned benefit of the GE9X, which is targeted at a 10% lower fuel burn than the GE90-115B used on the 777-300ER, as well as the improved efficiency of the 233-ft.-span wing. The higher-aspect-ratio, carbon-fiber-reinforced polymer wing is designed to give a 12% improvement in lift-drag ratio and will be characterized by a 787-like dihedral. “We are confident in the wing design. It produces incredible increases in lift and decreases in drag,” despite weighing more than the current metallic wing, adds Feldmann. “It's the fourth time we've done a large composite wing, and clearly we are going down the 787 derivative path.”

Within the broader context of Boeing's twin-aisle market strategy, the launch of the 777X also marks “the final chapter” of the repositioning of the widebody product line, says Scott Fancher, Boeing Airplane Development vice president and general manager. Following in the footsteps of the 787-8, -9 and -10 launches, the 777-8X and -9X bridge the gap with the 747-8, partially overlapping with the larger aircraft and providing a twin-engine replacement for 747-400s. “We sized up the -8X to take advantage of the -9X technology to give us an aircraft like the 777-300ER but with greater range and payload. The -8X, for instance, will be able to carry 17 tonnes more cargo than the A350-1000,” says Fancher. “With the -9X, we think that's where the heart of the widebody market is.”

Although Middle Eastern carriers such as Emirates, Etihad Airways and Qatar Airways were highlighted at Dubai as launch customers, Boeing says this does not mean the 777X is over-optimized for other users. Lufthansa was the first to actually commit to the 777X with an $11 billion deal to acquire 34 777-9Xs in mid-September. Vice President Nico Buchholz says, “by jumping first for the -9X, we also solicited in the contract what we wanted it to do.” The performance “box” created for Lufthansa's requirement also suits the other airlines, which worked with Boeing as a group to define the new family.

Clark says he can “understand the concern” of other carriers that the 777X has too much design input from the Persian Gulf carriers, leading to an aircraft that has more capabilities than other airlines need. However, he points out that Emirates also had a strong say in the design of the extremely popular 777-300ER. Emirates has been pushing GE to offer the GE9X engine at 105,000 lb., around 5% more thrust than planned. But Clark says higher engine thrust also leads to savings on the maintenance side, if carriers chose to derate engines when less power is needed. Other airlines would be able to take advantage of the full thrust in hot-and-high scenarios such as Mexico City or Bogota, Colombia.

Building on lessons learned from the troubled introduction of the 787, the new development will include a special focus on reliability. “You can design in reliability, and we are working with the launch airlines to do a demonstration-test of reliability in real airline environments and operations,” Feldmann says. “We have the systems and fuselage related to the 777, the wing and systems related to the 787 and the engine that's a relative of the GEnx and CFM Leap—so we know all of these aspects extremely well. That means we don't have to wait to see how that will be. We can see already where we had reliability issues early on, and we can redesign components and do the things to make sure our customer never sees [such problems].”

A key design feature is the folding wingtip that will allow the 777X to use the same airport gates and taxiways as the existing 777. “It unlocks tremendous capability in the aircraft,” says Feldmann. “The folding wingtip is an innovation that's relatively low-risk. It's not the 777 folding wing of yesterday. We have to get one wire across the fold for the light and that's it. The fold is 11 feet on each tip, so it's not much different to the size of winglets.”

Other changes from the current 777 include larger windows and a 787-style cabin, a hybrid laminar flow control (HLFC) drag-reduction system on the leading edge of the vertical tail and laminar-flow engine nacelles. “Both HLFC and laminar-flow nacelles were perfected on the 787, so here is another technology we understand and which is low-risk,” says Fancher. The vertical fin, although sized to approximately the same height and area as the current unit, has a more rakish 787-style design, reflecting aerodynamic and structural lessons learned on the aircraft as well as the integrated HLFC system.

Boeing aims to complete the overall design in 2014, with suppliers due to be confirmed “in the coming months,” Fancher says. Firm configuration will be set in 2015, detailed design is scheduled to follow in 2016 and production to begin in 2017. First flight of the 777-9X is expected in 2018, with flight tests running through 2019. The first 777-9X delivery is targeted for 2020, with initial deliveries of the -8X following 18 months later in early 2022. Engine development is planned to run slightly ahead of the airframe schedule, with final design in 2015 and the first engine test in 2016. Flight tests on GE's flying testbed are slated to start in 2017, with certification expected in 2018.

Tap the icon in the digital edition of AW&ST to watch a video of Guy Norris highlighting the 777X's features, or go to AviationWeek.com/dubai2013

Boeing 777-8X/9X and 777-200LR/300ER Comparison
  Boeing 777-8X Boeing 777-9X Boeing 777-300ER Boeing 777-200LR
Wingspan 233 ft. 5 in. 233 ft. 5 in. 212 ft. 7 in. 212 ft. 7 in.
Wingspan (folded) 212 ft. 9 in. 212 ft. 9 in. N/A N/A
Overall Length 228 ft.* 250 ft.* 242 ft. 4 in. 209 ft. 1 in.
MTOW 775,000 lb.* 775,000 lb.* 775,000 lb. 768,000 lb.
Max. Range (Standard Config.) 9,400 nm 8,400 nm 7,825 nm 8,625 nm
Seat Count (Three-Class Config.) 350 405 386 314
List price $349.8 million $377.2 million $320.2 million $296 million
First Delivery 2022 2020 2004 2006
Source: Boeing