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|