Winglet - Raked Wingtip

Raked Wingtip

Raked wingtips are a feature on some Boeing airliners, where the tip of the wing has a higher degree of sweep than the rest of the wing. The stated purpose of this additional feature is to improve fuel efficiency and climb performance, and to shorten takeoff field length. It does this in much the same way that winglets do, by increasing the effective aspect ratio of the wing and interrupting harmful wingtip vortices. This decreases the amount of lift-induced drag experienced by the aircraft. In testing by Boeing and NASA, raked wingtips have been shown to reduce drag by as much as 5.5%, as opposed to improvements of 3.5% to 4.5% from conventional winglets.

While an equivalent increase in wingspan would be more effective than a winglet of the same length, the bending force becomes a greater factor. A three-foot winglet has the same bending force as a one-foot increase in span, yet gives the same performance gain as a two-foot wing span increase.

For this reason, the short-range Boeing 787-3 design called for winglets instead of the raked wingtips featured on all other 787 variants.

Raked wingtips are installed on, or are planned to be installed on:

• Boeing P-8 Poseidon
• Boeing 747-8 Freighter
• Boeing 747-8 Intercontinental
• Boeing 767-400ER
• Boeing 777-200LR
• Boeing 777-300ER
• Boeing 777 Freighter
• Boeing 787-8
• Boeing 787-9