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

From:         egotrip@lesol1.dseg.ti.com (Mike Neus)
Organization: Texas Instruments
Date:         12 Oct 96 02:36:04 
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In article <airliners.1996.1895@ohare.Chicago.COM>, Tomas Stephanson said...
>
>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?
>
>Why does Boeing not want to extend the upperdeck the full length of
>the aircraft, is it not economical, aerodynamic, weight penalty?

The 747 was originally designed as a cargo plane.  Once you understand this,
the shape of the 747 is logical.  To maximize cargo space and allow the nose
of the plane to open for fast loading/unloading, the best place for the
cockpit is on top of the fuseloge, hence the upper deck.  I'm not sure why
the deck is as long as it is.  One could speculate it was for aerodynamics
(it makes sence to make the back of the cockpit a gental slope for this
reason alone) or somebody invisioned it as carrying a small number of
passengers who wanted to go with the cargo, or maybe it even would hold
smaller cargo.

Ultimately though, the space was obviously used for passengers and in fact
the hump on the original 747-100 is relatively short, while the hump on the
higher capacity -400 is much longer.  The only practicle reason I can think
of not to extend it all the way back is the entire back end of the 747 might
have to be redesigned for extra support and the tail moved up to get it out
of the turbulence, etc.  Obviously, this would be quite an expense.