The Boeing 777X is the latest series of the long-range, wide-body, twin-engine Boeing 777 family from Boeing Commercial Airplanes. The 777X features new GE9X engines, new composite wings with folding wingtips, greater cabin width and seating capacity, and technologies from the Boeing 787. The 777X was launched in November 2013 with two variants: the 777-8 and the 777-9. The 777-8 provides seating for 384 passengers and has a range of 8,730 nmi (16,170 km) while the 777-9 has seating for 426 passengers and a range of over 7,285 nmi (13,500 km). The 777-9 first flew on January 25, 2020, with deliveries expected to commence in 2024.
In 2011, Boeing refined its response to the revamped Airbus A350 XWB with three 777X models, targeting a firm configuration in 2015, flying in late 2017 or 2018, and entering service by 2019. The 407–passenger 777-9X should stretch the 777-300ER by four frames to 250 ft 11 in (76.48 m) in length, for a 759,000 lb (344 t) maximum take-off weight (MTOW) and powered by 99,500 lbf (443 kN) engines, targeting per-seat 21% better fuel burn and 16% better operating cost. The smaller 353-seat 777-8X was to stretch the 777-200ER by ten frames to 228 ft 2 in (69.55 m), with a 694,000 lb (315 t) MTOW and 88,000 lbf (390 kN) turbofans to compete with the A350-900 with improvements over the -200ER like the 777-9X over the 777-300ER. A 8LX with the 9X MTOW would have a 9,480 nmi (10,910 mi; 17,560 km) range. The current 777-200LR/300ER have a 775,000 lb (352 t) MTOW.
A new carbon-fiber-reinforced polymer (CFRP) wing with a wingspan of 213 or 225 ft; 2,560 or 2,700 in (65 or 68.6 m) with blended winglets, or up to 233 ft 5 in (71.1 m) with raked wingtip provide for a 10% larger wing area. It would fall into ICAO aerodrome code F like the 747-8 and A380 but with 22 ft 6 in (6.9 m) folding wingtips it would stay within the 213 ft 4 in (65.02 m) code E like current 777s. Horizontal stabilizers would be extended.
The 777X has a new longer composite wing with folding wingtips. Due to this, the 777x is the first aircraft to have 'Wingtip Controls' inside the cockpit. Based on the 787 wing but with less sweep, the new wing has a higher lift-to-drag ratio, aspect ratio increased from 9:1 to 10:1, area increased from 4,702 to 5,562 sq ft (436.8 to 516.7 m2), and usable fuel capacity increased from 320,863 to 350,410 lb (145,541 to 158,943 kg). Folding wingtips are a first for commercial aviation.
To stay within the size category of the current 777 with a less than 213 ft (65 m) wingspan, it features 11 feet (3.5 m) folding wingtips with the folding wingtip actuation system made by Liebherr Aerospace. The mechanism was demonstrated for Aviation Week at the Boeing Everett Factory in October 2016; the folding movement should be complete in 20 seconds and be locked in place at the end. Specific alerts and procedures are needed to handle a malfunction.
As existing regulations do not cover the folding wingtips, the FAA issued special conditions, including proving their load-carrying limits, demonstrating their handling qualities in a crosswind when raised, alerting the crew when they are not correctly positioned while the mechanism and controls will be further inspected.Those ten special conditions were to be published on May 18, 2018, covering worst-case scenarios.
Transported by sea from Subaru in Nagoya to Everett, the center wing-box is similar in size to the legacy 777 but is more reinforced and heavier, with more titanium.
The internal cabin width is increased from the previous 777 models' 231 to 235 in (587 to 597 cm) through thinner interior cabin walls and better insulation to allow 18.0 in (46 cm) wide seats in 10-abreast economy. The 777X will feature cabin design details requiring structural changes that were originally introduced on the Boeing 787 Dreamliner: larger windows, higher ceilings, more humidity and lowered cabin altitude to 6,000 ft (1,800 m). Its flight deck is similar to the 787 cockpit with large displays and head-up displays, controls for the new folding wingtips, and touchscreens replacing cursor control devices. Windows are dimmable.
For the longer 777-9, new engines should improve fuel consumption by 10%, with the longer, carbon-fiber wings adding an estimated 7% improvement. As 4 to 5% of fuel savings is lost from the 12 tons heavier basic structure of the larger airliner, the net fuel efficiency gain is projected to be 12 to 13%. Ten-abreast seating instead of nine with a longer fuselage enable a reduction in fuel burn per seat of 20% compared to the 365-seat 777-300ER. The longer-range, 355-seat 777-8 should have a 13% improvement in fuel consumption with 10 fewer seats than the -300ER.[78] Boeing forecast a 33% better cost per seat than the 747-400 and 13% better than the 777-300ER.
Its maximum takeoff weight is targeted for 775,000 lb (351.5 t) like the 777-300ER but Boeing hopes to have at least a 10,000 lb (4.5 t) margin at introduction. Boeing predicts the -8 to be 4% more fuel efficient and cost effective than the A350-1000, while the -9 would be 12% more fuel efficient and 11% more cost effective. Lufthansa, when it ordered both, stated the Airbus A350-900 and the 777-9X will consume an average of 2.9 L/100 km per passenger.