Feathers save fuel

SEATTLE — Boeing Co. announced a new twist Wednesday morning to its design for the forthcoming 737 MAX jet: A raked, “dual feather” winglet concept that it says will provide an extra 1.5-per-cent gain in fuel efficiency. That’s on top of the 10- to-12-per-cent fuel burn improvement over the current 737 that Boeing already has claimed for the MAX with its new engines and various small aerodynamic improvements. Renderings provided by Boeing show the wingtip swept slightly backward, or raked, and with a tip that splits in two, one longer end pointing up and the other shorter one down, known as dual feather.