Re: Why not a full length upper deck on a 747-600X

From:         faurecm@halcyon.com (C. Marin Faure)
Organization: Northwest Nexus Inc.
Date:         12 Oct 96 02:36:04 
References:   1
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In article <airliners.1996.1895@ohare.Chicago.COM>,
tomas@medialab.ericsson.se (Tomas Stephanson) wrote:

> I saw some pictures on the new proposed 747-600X and saw that the
> upperdeck did not extend the whole length of the aircraft compared
> to the Airbus 3XX.
> Why does the 747 have a upper deck in the first place? Was it
> for futre expansion?

The 747 was intended from the outset to be a freighter, with its passenger
role being taken over by SSTs.  So the flight deck was placed above the
main deck to facilitate loading large items through the nose.

> Why does Boeing not want to extend the upperdeck the full length of
> the aircraft, is it not economical, aerodynamic, weight penalty?


Extending the upper deck all the way to the tail would require a complete
aerodynamic redesign of the tail surfaces.  Extending the 747's upper deck
and doing nothing else would cause directional stability problems.  Plus,
our studies have shown that the deck-and-a-half arrangement is the best
way to accomodate both passengers and freight.  A full double deck
arrangement like the proposed A-3XX is better for passengers only, but not
as good as a deck-and-a-half for passengers and revenue freight.  And
revenue freight often makes more money for the airline than the passengers
sitting on floor above it...

C. Marin Faure
   author, Flying a Floatplane