The Boeing 777 is a popular twin-engine widebody long-haul airliner. Since its introduction with United Airlines in June 1995, Boeing has delivered more than 1,600 examples across all of its variants. It is also currently developing a next-generation ‘triple-seven’ series, known as the 777X. However, in contrast to several other Boeing designs, aircraft from the 777 family do not feature winglets. But why is this the case?
What purpose do winglets serve?
In a cost-driven industry such as commercial aviation, winglets are a useful money-saving tool for airlines. These vertical extensions of an aircraft’s wingtips reduce the amount of aerodynamic drag caused by the aircraft as it cuts through the air. This drag is typically associated with the vortices that an aircraft’s wingtips create in flight.
Winglets help to reduce the size of these vortices, and, subsequently, the amount of drag. This has a useful knock-on effect in that it improves fuel efficiency and, subsequently, range. Furthermore, consuming less fuel also saves airlines money. This feature has several different designs, including canted, blended, sharklet, and split scimitar winglets.
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Why does the 777 not have winglets?
One reason that the 777 does not feature such wingtip extensions is the operational limits these would place on the aircraft. The 777-200LR and -300ER variants of the aircraft have a wingspan of 64.8 meters. This only just falls below the upper limit for the ICAO’s aerodrome code E.
The upper limit for this category is 65 meters, and adding winglets would exceed this. This would cause the aircraft to be classified under aerodrome code F. This categorization is the same as larger aircraft such as the Airbus A380 and Boeing 747, and would limit its versatility. Manufacturers also have to consider the added weight that winglets give to an aircraft.
Furthermore, later designs, such as the 777F pictured below, feature raked wingtips. This profile change at the end of the wings offers similar efficiency benefits to winglets. As such, that left little need for Boeing to also extend the type’s wingtips upwards. One can also find similar raked wingtip designs on its 747-8, 777X, and 787 ‘Dreamliner’ aircraft.
Wing technology on the upcoming 777X
Looking to the future, the upcoming Boeing 777X series will boast a variety of technological improvements over its predecessors. One of these futuristic aspects will be folding wingtips. Boeing is set to be the first manufacturer to deploy such technology on a commercial airliner. However, interestingly, its European competitor Airbus also patented a similar system in 2014.
The Boeing 777X’s folding wingtips will offer additional versatility to its operators. This is because, normally, its 71-meter wingspan would be so wide that it would fall under the ICAO’s aforementioned aerodrome code F. However, by folding the wingtips inwards on the ground, this is reduced to 64.8 m.
Much like previous 777 triple-seven variants, this means the 777X is just narrow enough to be classified under aerodrome code E. As such, operators will be able to fly the 777X to a greater variety of airports than if it did not have this feature. Furthermore, as it shares the same category as older 777s, this will allow for greater flexibility in terms of swapping between variants.
What do you make of the Boeing 777 family as a whole? Have you ever flown on one, or maybe even multiple triple-seven variants? Let us know your thoughts and experiences in the comments!