Re: Jet Engine Containment/GE90

From:         "Scott M. Thomson" <AAEJJST@snds.com>
Organization: Sundstrand Corporation
Date:         13 Sep 96 03:03:32 
References:   1 2 3
Followups:    1
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H Andrew Chuang wrote:
>
> In article <airliners.1996.1710@ohare.Chicago.COM> MeyerTed (meyerted@aol.com) wrote:
>
> [snip]
>
> > First, the GE90 does not have "a much heavier fan blade."  These
> > blades are made of composite materials and, although they are
> > dimensionally larger, are about the same weight or lighter than
>                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > those of our competitors.
>   ^^^^^^^^^^^^^^^^^^^^^^^^
>
> [snip]
>
> I believe this statement is false.  The weight per unit volume of
> the GE90 composite fan blade is no doubt lighter than the titanium
> fan blade of either the PW4000 and the Trent 800.  However, being
> at least 20% larger in area and having a metal leading edge guard, I
> believe the GE90 fan blade is heavier than that of your competitors.

I think the key issue with the composite blade vs. titanium blade
discussion is the weight savings of the containment band around the fan
case.  I believe this is based on the analysis that the composite blades
don't fail at the root fitting, so not as much mass needs to be contained
(unlike titanium fan blades)?  This is reported to have resulted in a
several hundred pound weight savings for the GE90.