Re: Why no wingtips for B777???

Date:         31 Jul 97 12:30:26 
From:         k_ish <kenish@ix.netcom..com>
Organization: Netcom
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C. Marin Faure wrote:
> 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.

Also, the efficiency improvement from winglets is only fully realized at
high altitude sustained cruise.  Although winglets yield an efficiency
increase at any altitude/airspeed, this improvement does not offset the
weight and manufacturing penalties C. Marin describes.  Since the 737
flies relatively short flights and spends a larger percentage of its
time in climb or descent (compared to, say, a 747-400), winglets don't
make sense.  In fact, there is a 747-400 Domestic which is used for
high-density short hops (1-2 hours) within Japan.  It does not have
winglets (and has structural enhancements to handle the higher number of
flight cycles).

Ken Ishiguro