Re: Why no wingtips for B777???

Date:         01 Aug 97 04:04:13 
From: (C. Marin Faure)
Organization: Northwest Nexus Inc.
References:   1 2 3
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In article <airliners.1997.1597@ohare.Chicago.COM>, wrote:
> 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).

The Domestic 747-400s Mr. Ishiguro describes will spend their first years
in service in short-haul service which puts a lot of cycles on the
airframe but not a lot of hours.  When the airframes become high-cycle,
the plan is to fit the -400's wing extensions and winglets (and whatever
other modifications are necessary to make it identical to "normal" -400s)
and put them in long-haul service which puts a lot of hours on the
airframe but not many cycles.  The theory behind this is that it will
maximize the revenue life of the plane.

C. Marin Faure
  author, Flying A Floatplane