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

From:         drinkard@bcstec.ca.boeing.com (Terrell D. Drinkard)
Organization: The Boeing Company
Date:         21 Oct 96 02:29:18 
References:   1 2
Next article
View raw article
  or MIME structure

In article <airliners.1996.2091@ohare.Chicago.COM>,
Mike Neus <egotrip@lesol1.dseg.ti.com> wrote:
>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?

Not initially, no.  It just sort of turned out that way.

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

Yes.  :-)

>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.

Actually, it has the cockpit on the upper deck to avoid the weight
penalties associated with the 9-G rigid barrier which would have been
required with a flight deck in the path of decelerating cargo pallets.
Loading and unloading through the nose was a secondary consideration, if in
fact, it was considered at all.

It is as long as it is (all three lengths that I know of off hand) for two
reasons.  First, Juan Trippe demanded that the upper deck be lengthened
during the preliminary design in order to put paying passengers up there.
Secondly, Trippe had a good idea, and Boeing has lengthened the upper deck
twice and will be lengthening it for the fourth time on the -600X.
Initially, the upper deck was much smaller and only had room for the flight
deck and the airconditioning ductwork.

>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.

Nope.  The basic reason not to do it is drag.  Too much of it for too small
a return in increased revenues (the additional passenger bags displace revenue
cargo, so the trade isn't as clean as you might think).
--
Terry
drinkard@bcstec.ca.boeing.com
"Anyone who thinks they can hold the company responsible for what I say has
more lawyers than sense."