Re: Airliner Windows

Date:         08 Sep 97 02:03:47 
From: (Andrew Muir)
Organization: Nobody but me
References:   1 2
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In article <airliners.1997.2051@ohare.Chicago.COM>,
   Steven McDowell <> wrote:

>I understand the size problem as being a structural necessity. I am
>wondering about placement, though. Putting the windows a little higher
>would be nice.

An airliner fuselage is essentially a cylinder with internal structure.
Thhe skin is reinforced internally with circumferential frames for hoop
strength and stringers (running the length of the fuselage) for
longitudinal and bending strength.  The combination of the stringers,
frames and skin work on torsion.

The stringers are placed approximately equally around the circumference
of the cabin.  Windows are placed between stringers and frames, where
there is empty skin to penetrate.  On the 737, stringers are approximately
10 inches apart.  The centerline of the window line is at the stringer 12
location - twelth stringer from the top (Stringer 1 is at the top of the
fueslage in the aircraft BL 0 and the stringers are counded down from
there - Left side 2L, 3L .. Righte side 2R, 3R ...).

To put in the windows, Stringer 12 is replaced by the window forging that
runs from stringer 11 to 13.  This is done by design, and in actuallity
the only place that stringer 12 exists is at the blank window locations
just infront of the wing.  Now to change the placement of the window
vertically stringers 11 & 13 would have to be repositioned and that would
screw-up the nice even spacing of structural elements that we engineers
love.  PLan b would be to increase the diameter of the fuselage to maintine
the spacing, not really worth it.

So ultimately, structural concerns win out an the passenger just has to
bend down to see the clouds outside.