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I would like to know what airfoils are used for the Boeing 737 winglets.

SentryRaven
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Flanker
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1 Answers1

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Aviation Partners Boeing, a joint venture between the two companies, developed the winglets for 737NG, 757 and 767 aircraft. They are offered in two varieties, a "blended" version, which is where the wingtip is upturned to near vertical and a newer, "split scimitar" version which adds a downward pointing tip as well. They are made of a composite material with aluminium leading and trailing edges.

Their purpose is not to generate lift, but rather, prevent wingtip vortices (which generate a significant amount of induced drag) from spilling onto the top of the wing.

The design characteristics of the blended winglet are described in US Patent 5,348,253.

newmanth
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    They actually do generate lift by increasing the pressure differential at the wingtip. But they do not prevent those mythical "wingtip vortices", and the reason for induced drag is lift creation. All they do is to spread out lift creation over a slightly greater air mass, and the reduction in drag is easily lost with a little sideslip. If you add the additional friction drag, their drag reduction is marginal at best. – Peter Kämpf Jul 02 '14 at 19:16
  • You're right, it is impossible to prevent wingtip vortices. Winglets produce a forward thrust inside the circulation field of the vortices to reduce their strength. This, in turn, reduces the amount of induced drag. Airlines using winglets experience fuel burn reductions of up to 5%, hardly a trivial amount. – newmanth Jul 02 '14 at 21:27
  • … using new aircraft with new engines. Please compare apples with apples, and you will see how little winglets actually do. Those 5% come from comparing a 737-300 with a 737-700. – Peter Kämpf Jul 02 '14 at 21:41
  • @newmanth, I was asking about the airfoils used in the Boeing winglets, not about what winglets are and who developed them. I am sorry, but your answer is completely irrelevant. Also irrelevant is your reference to Gratzer's patent. Also, your explanation of how winglets reduce induced drag is erroneous. Please, if you are not fully competent in the field, do not provide others with faulty information. Thank you. – Flanker Jul 04 '14 at 18:16
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    @Flanker for continuity they keep using the same airfoils as in the wing. – Trebia Project. Feb 09 '15 at 06:55
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    @PeterKämpf Airbus was able to get 3.5-4% fuel burn netly (including airframe structure weight increase) when retrofitting the A320 http://airinsight.com/2012/11/27/airbus-reports-better-than-projected-sharklet-performance-for-a320/#.VNhZQPmG-AU – Trebia Project. Feb 09 '15 at 06:57
  • @TrebiaProject. You can't really call that a reputable source. In my opinion the A320neo's improved efficiency is mainly due to the engines and it is difficult to prove how much the drag is reduced during all flight stages by the winglets. I see they also mainly experienced the reduction in fuel burn on long-haul flights. – Jonny Feb 23 '15 at 09:53
  • @Jonny that document is describing the improvement of sharklet compared to previous standard. Nothing about NEO is commented. You can find similar information (claiming 4%...) in Airbus press release http://www.airbus.com/presscentre/pressreleases/press-release-detail/detail/airbus-launches-sharklet-retrofit-for-in-service-a320-family-aircraft/ . There are 2 different projects: sharklet modification (in service) and NEO (in Flight Test). – Trebia Project. Feb 23 '15 at 10:29
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    a joint venture between the two companies which companies? – Federico Feb 25 '15 at 08:49
  • @Federico "Aviation Partners Boeing" => "Aviation Partners" + "Boeing" - the clue's in the name. It's also underneath the logo in the link he posted. – Jon Story Feb 25 '15 at 11:42