Airline Pilot Central Forums - B767 with blended wing tip.

Airline Pilot Central Forums (https://www.airlinepilotforums.com/)

- Major (https://www.airlinepilotforums.com/major/)

- - B767 with blended wing tip. (https://www.airlinepilotforums.com/major/29074-b767-blended-wing-tip.html)

B767 with blended wing tip.

That's a big winglet. Very sexy.

I know that a lot of airlines are retrofitting winglets to their fleet for aerodynamic efficiency reasons. Why is it then, that the 787 and the 747-8 don't have the typical upturned winglets? They have a winglet of sorts, but it's more of a tapered edge that is parallel with the rest of the wing. Anybody have any ideas?

Not sure about the 747-8, but the 787 has a different wing than other Boeing aircraft - lots of taper and twist to reduce induced drag and increase the aspect ratio...

The boeing 787 uses a different technology called raked wingtips. They are actually more efficient than these blended winglets. The wing structure allows the wingtips to curve up during flight, which has the same effect as winglets. Winglets are basically only more efficient as a retrofit option; new aircraft will be designed either with a higher aspect ratio or raked wingtips to begin with. It turns out for most aircraft that "folding" the winglet down and making a higher aspect ratio wing would have usually been the best option during the design process anyways...

Winglets are decades late to this biz.

Now, if the airlines would raise fares enough to shore up the losses...

Quote:

Originally Posted by Duke990 (Post 431750)

The company that is doing the winglet retrofits holds the patents for them and Boeing isn't too keen about winglets in the first place, but is going along with the retrofits because that is what the customers want.

Here's something on this from today's AIAA daily news letter (subscription required):

Quote:

Larger blended winglets used to increase jets' fuel-efficiency.

The Seattle Post-Intelligencer (7/23, Wallace) reports that Aviation Partners's large blended winglets have been certified to appear on a variety of Boeing planes. And, "[o]n Sunday, the blended winglet program from Aviation Partners Boeing moved up in size when they flew for the first time on an American Airlines 767-300ER." The winglets are 11-feet tall and "work by reducing drag created by the vortices that are generated by a plane's wingtips." The company "estimates that its blended winglets for the 767-300ER will save up to 6.5 percent on fuel consumption, or a savings of roughly 500,000 gallons of jet fuel per aircraft per year for operators with the longest average sector lengths and highest aircraft utilization rates." Blended winglets differ from traditional winglets in that they "gently curve up, as if they are part of the wing." Though "[i]ncreasing the wingspan can produce the same results," many "wings of jetliners can't get any longer and still fit at airport gates."

I would tend to agree winglets are not in use on the 787 probably because of the more advanced wing design that does away with the need for them- composites allows more flexibility in airfoil shapes. The link above apparently goes back to the same article.

Daily fun fact: The designer of the blended wingtips for the 767-400 was hired away from Callaway by Boeing...he used to design golf balls.