Re: Superfan

Date:         25 Nov 97 03:26:04 
From:         domk1031@sp.zrz.tu-berlin.de (Burkhard Domke)
Organization: Technical University of Berlin, Germany
References:   1
Followups:    1
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On 22 Nov 97 20:41:27 , Marc Schaeffer <marcmsc@geocities.com> wrote:

>I would like to know what happens in the domain of the Superfan engines.
>
>[...]
>
>- What about reliability, weight, costs, would they not reduce the
>expected cost advantage (-20% for fuel) ?

A major obstacle is the non-availability of a 50.000+ SHP gearbox
satisfying the weight, reliability, durability and cost requirements.

Fuel expenses typically account for cca 25% of the DOC. Hence a
decrease in TSFC by 20% would translate into a meager 5% overall
advantage, given the highly unlikely case there were no additional
costs inherited with geared, shrouded Propfans over conventional
turbomachinery.

Burkhard