Re: Superfan

Date:         25 Nov 97 03:26:05 
From:         Marc Schaeffer <>
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H Andrew Chuang wrote:

> >- What's the status on UHB engines nowadays, is it under
> >development/trials (PW/RR/GE/IAE/CFM ...) somewhere ?
> I believe PW is probably the leader in this technology due to its past
> experience developing a gearbox-driven propfan to compete with GE's
> unducted fan (UDF).  PW was very interested in developing an Advance
> Ducted Prop (ADP) engine.  However, I have not heard much about it,
> lately.  I am not aware either GE or RR being actively pursuing this
> approach.
> >- What about reliability, weight, costs, would they not reduce the
> >expected cost advantage (-20% for fuel) ?
> I don't think weight is an issue.  Even though you will have a much
> larger fan, there will be less fan blades and you won't need a thrust
> reverser because of the variable-pitch fan.  However, you can find out
> about the reliability only when it's in the field.

  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 ...

I'm just dreaming :-)
Marc Schaeffer, Luxembourg //
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