Winglets?

[Bavarian Chef]

I meant wingtip fence, but for some reason I recall hearing they have the same benefit as a stall fence.

I should be smarter on this stuff...

 

[SkiFishFly]

I believe the Airbus wingtip "fences" (they aren't really winglets) only influence the span-wise flow thereby reducing the wingtip vortices and producing a small decrease in drag.

 

[BornFromJets]

So does anyone know for certain why an aircraft like the 777 doesn't have them? I was asked that not too long ago, but my answers were guesses more than anything.

 

[Lear70]

More than likely because of the wingspan and the twisting motion on the wing.

That would just be an educated guess, however...

 

[Ben Johnson]

the 777 doesn't have winglets because the wing is designed more or less perfect. Metal needed to renforce the energy forces created and the weight on the wing exceeds the usefullness of having a winglet on the 777. the 747-440 winglets actually are for marketing. the extra weight to renforce the wing actually counter acts the usefullness of having them. at that time boeing was struggling to compete with airbus... a big wintip fan. although the 73 and 75 series seem to be a different case. the addition of a windlets has increased range and efficentcy such that the mod. is worth the money or atleast that is what the bean counters are telling us...

 

[ackattacker]

the 777 doesn't have winglets because the wing is designed more or less perfect. Metal needed to renforce the energy forces created and the weight on the wing exceeds the usefullness of having a winglet on the 777. the 747-440 winglets actually are for marketing. the extra weight to renforce the wing actually counter acts the usefullness of having them. at that time boeing was struggling to compete with airbus... a big wintip fan. although the 73 and 75 series seem to be a different case. the addition of a windlets has increased range and efficentcy such that the mod. is worth the money or atleast that is what the bean counters are telling us...

Also some 777's have raked wingtips which has a beneficial effect similar to winglets.

 

[Huck]

They told me down at alabama polytechnic that they produce roughly the same effect as if you iron them flat - i.e. increased aspect ratio.

Also make a dam fine place to vent fuel tanks....