Raked wingtips

[jrsanch]

We have seen the new craze towards winglets in aircrafts that didn't have them from their inception, but new designs are coming with "raked wingtips".
Is this a better design? Will it override winglets in the future?

[Gillegan]

All wings are unique in their specific lift characteristics and need to be considered accordingly. In both cases (raked wingtips and winglets), the designer is trying to mitigate the loss of efficiency due to wingtip vortices. Winglets can be fitted to just about any wing but have the tradeoff of increased structural weight. "Raked" wingtips have the advantage in that they reduce the efficiency loss due to the wingtip vortices without much of the structure of a winglet (though there is the extra structure for the increased span) but really need to be designed into the wing from the outset. The raked wingtip works by tailoring the lift profile of the wing to reduce the vortices. For an already existing wing, the solution in most cases would be the addition of a winglet. I believe that most airlines that are ordering their new 737's with the winglet options are basing their decision on a minimum average stage length below which the additional weight of the winglet is more of a penalty than the increased efficiency in cruise.
The 787 and 747-800 appear to be designed with a large amount of flex in the wing which would affect the lift profile. It almost looks like they are getting the best of both worlds with their design. I would be curious if this is the case or if there is something else going on there.

[What Traffic]

Winglets also tend to take up less parking space on the ramp, when that is an issue.