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

From: (Terrell D. Drinkard)
Organization: The Boeing Company
Date:         28 Oct 96 03:06:36 
References:   1 2 3
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P. Wezeman <> wrote:
>On 12 Oct 1996, Jim Young wrote:
>> The really big reason is aerodynamics.  A little things called area rule
>> (look it up in any basic aero book or email me if you want an explanation)
>> plays a big part in the drag of an airplane.  When Boeing originally
>> streched the 747-200 to the longer upper deck on the -300, the drag of the
>> airplane actually went down, even though there was more fuselage.
>   Would this mean that if, say, the Boing 757 were to be enlarged to carry
>more passengers that there would be less drag if instead of extending the
>fuselage fore and aft with the existing cross section, the fuselage was
>made double deck in front of the wings and extended single deck aft of the
>wings so as to maintain weight and aerodynamic balance?


No.  The original 747 had an area-rule drag hit due to the cross-section
increase then decrease then increase then decrease.  It was not happy.  The
757, on the other hand, does the increase then decrease and that's it.
Adding an upper deck (what were you going to propose? Two abreast?  :-))
would not be beneficial, even if were only over the forward part of the

"Anyone who thinks they can hold the company responsible for what I say has
more lawyers than sense."