Re: Why no wingtips for B777???

Date:         28 Jul 97 01:13:29 
From:         faurecm@halcyon.com (C. Marin Faure)
Organization: Northwest Nexus Inc.
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In article <airliners.1997.1482@ohare.Chicago.COM>, "Lee Tze Yen, Bob"
<bunnylee@pacific.net.sg> wrote:

> I've always been pondering over this question:
>
> Why are winglets not used on the newer Boeing aircraft, for example the
> B777, and the originally proposed B747-500X/600X??? If I'm not wrong, these
> winglets help improve the fuel efficiencies of the B747-400. And why are
> winglets used on the latest B767-400ERX????
>
> In contrast, winglets are used on all the new Airbus models, especially the
> A330/A340 variants.

Winglets are a compromise, used to improve the efficiency of an existing
or flawed wing design.  If you have the opportunity to design a wing from
scratch and you get it right, as was done with the 777 and the New
Generation 737 family, there is no reason to install winglets.  While they
may increase the efficiency of some wings, they are a pain in the butt
during manufacture and they add unwanted weight.  The only winglets that
truly work well are the ones on birds like ravens, hawks, eagles, condors,
etc.  They work because the bird can put them in when they're helpful and
get rid of them when they aren't, and they're almost infinitely variable.
If we could figure out how to do that on an airplane reliably and with no
weight penalty, we'd really have something.  Incidentally, one of the most
efficient wings in the sky (according to the airlines who fly it, not me)
is the 757 wing.  One of the "problems" 757 pilots have is slowing the
plane down, the wing is so efficient.  And neither it nor the 767 have
winglets.

C. Marin Faure
  author, Flying A Floatplane