Re: Superfan

Date:         29 Nov 97 03:24:33 
From:         Chuanga@cris.com (H Andrew Chuang)
Organization: Concentric Internet Services
References:   1 2 3
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In article <airliners.1997.2757@ohare.Chicago.COM>,
Marc Schaeffer  <marcmsc@geocities.com> wrote:
>
>  With todays engines being very close one-another, this UHB technique
>would have the potential to provide an important technical leadership to
>one of the three engine makers. Is the risk and/or the development costs
>that high that nobody even wants to build a prototype of an existing
>engine with UHB technique. Just imagine that one of the three
>engine-makers for the 777 would go for the UHB technique. The range
>advantages would be so dramatic that the two other competitors could
>stop produicing their engines ...

The bypass ratio of the GE90 is around 9 to 10, much higher than its
competitors (the PW4084/90/98 and Trent 800 [bypass ratio of around 6]).
(Various "superfan"/UHB designs have bypass ratio of around 12 to 15.)
The GE90, even though a heavier engine, does have a slightly better fuel
efficiency.  However, efficiency alone does not sell the engine.  GE is
certainly not too successful in marketing its GE90.  The right technology
at the right time will make a manufacturer the leader in the market.
Is an ultra-high-bypass engine the answer at this time?  I kinda doubt
it!