The Boeing 777X will be the American manufacturer’s first new single-deck widebody airliner since the 787 ‘Dreamliner.’ The first-generation 777 first flew commercially in 1995, with United as the launch customer. The ‘X’ variant is set to boast several technological innovations that render it more advanced than its predecessor. One of these is its folding wingtips – but why will the 777X have this feature?
Next-generation wing design
As Simple Flying reported last year, the 777X’s wings will be based on the design of those of the 787. The striking wing sweep on the Dreamliner makes it very easily recognizable compared to Boeing’s older designs. The ‘raked’ design of the 787’s wings has a similar function to winglets. Many airliners use these to increase fuel efficiency and, subsequently, operational range. The Airbus A350’s wings are also swept back at a similar angle.
The Boeing 777X will not have quite the same wing sweep angle as the Dreamliner. Nonetheless, their surface area will be nearly 20% larger (5,562 square feet compared to 4,702 on the 787). A higher lift-to-drag ratio is another consequence of this re-shaping process. This will result in an increase in usable fuel bulk, from 320,863 lb to 350,410 lb.
All of these aspects work towards some of Boeing‘s most convincing selling points for the 777X. These include “10% lower fuel use and emissions and 10% lower operating costs than the competition.” A further pull factor for potential customers is the type’s increased operational range. This will be 8,730 NM (16,170 km) on the 777-8, and 7,285 NM (13,500 km) on the larger 777-9. Both of these figures are superior to their first-generation counterparts.
Practical purposes for the design
However, the motivations for Boeing to revolutionize the 777X’s wing design were not just based on fuel economy. At 71 meters, FlightGlobal reports that the 777X will boast Boeing’s widest ever wingspan. In contrast, first-generation 777 wingspans measured just 61m (777-200ER/300) and 64.8m (777-200LR/300ER). The Boeing 747-8 comes closest, at 68.5m.
As a result of its increased wingspan, the 777X would fall under the ICAO’s aerodrome code F. This would limit which airports the type can serve, placing it in the same category as the Boeing 747 and Airbus A380 ‘superjumbo.’
However, when the folding wingtips are in operation, the 777X’s wingspan measures just 64.8m. As such, it just about falls into the next lowest category, code E, for which the upper limit is 65m. This means that the type is far more versatile than its unfolded wingspan would have potential customers believe.
Another aspect of the 777X’s versatility is that it will have the same airport categorization as its first-generation predecessors. This will offer operators increased flexibility in terms of swapping between the types should operational requirements dictate this. This should prove a useful selling point for Boeing as it looks towards the 777X’s commercial launch. As it stands, this will be with Lufthansa in 2022.
How do the folding wingtips work?
The exact details of the 777X’s fold mechanism have not been made public. However, Boeing has designed the system of locking pins and latches to meet the safety requirements of any flight-critical system.
The wingtips will fold inwards automatically after landing, within 20 seconds of the aircraft reducing its speed to below 50 knots. This will mean that, by the time it arrives at its gate, the 777X will be compliant with ICAO code E, exemplifying its impressive operational versatility.