Re: 707 window thoughts

Date:         25 Jun 99 01:33:07 
From:         "PSLEIGHT" <>
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Steve Lacker wrote in message ...
>Jim1inDC wrote:
>> Recently I sat next to a "missing window" on both a 737-300 and a 747-(200?)
>> and could hear, on both, the unmistakable ROAR of air headed from below to the
>> overhead air conditioning.  I've noticed that most Boeing (and many Airbus', as
>> I recall) have this 'missing window' arrangement, and that it's usually near
>> the leading edge of the wing.
>I've noticed that many versions of the MD-80 have a single missing
>window on the left-hand side near the front  of the coach section.
>Coincidentally, this is above the point where the ground AC duct plugs
>into the aircraft... ;-)

The air conditioning packs on most modern jets are located to the rear of
the leading edge of the wing. So that are from the mixer which takes air
from the air con packs and the recirculation fans can reach the overhead
distrubution ducts, there is a need for riser ducts. These rise from the mix
manifold to the distrubution duct that runs the length of the mid section of
the aircraft. Unfortunately the riser ducts of such as width that they need
to be hidden from view by the trim of the cabin interior and also require
windows to be obscured.

The hissing noise is indeed the air being supplied by the air con packs. If
it wasn't for this air con noise the pressurisation would fail due to lack
of air in flow so bare that in mind if you are stuck by a blank window....