Re: Oxygen - Concorde

Date:         24 May 99 01:52:25 
From:         Marc Schaeffer <"marcmsc$$$"@cmdnet.lu>
Organization: http://surf.to/orders
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Don Stauffer wrote:

> An interesting problem- even with oxygen masks one cannot breath above about
> 45,000 feet.  When it was announced that the Concorde was going to be flying
> at 60,000 feet, I wondered how in the world they could maintain a breathable
> atmosphere if a cabin window blew.  Turns out the compressor for cabin
> pressurization is so strong it can maintain a breathable cabin altitude even
> with two windows gone!

Absolutely correct, I asked one of my colleagues who is a retired
Concorde pilot, here his reply :

The design case requirement for Concorde was to be able to sustain the
loss of two cabin windows ( their size was in fact decreased in
Production model to meet this!) and for the condition to be survivable.
By survivable is approximately meant that should the failure occur at
maximum cruise altitude (ie 60000ft) then the cabin altitude should not
exceed 24000ft and the flight crew and passengers be provided with
adequate oxygenation during the period necessary to descend to a safe
altitude (eg around 10000ft).This is really the same sort of requirement
that applies to all airliners that cruise at altitudes where oxygen is
necessary for survival.

To meet this sort of requirement a pressure failure drill is drawn up
which involves the crew donning oxygen masks and setting the aircraft up
on a predefined profile (passenger oxygen masks are auto deployed as in
all airliners where necessary). The drill is proven and tested and in
the case of Concorde it had to be shown that the crew could be breathing
oxygen within 5 seconds, and a special mask was made to meet this
requirement as most others take rather longer to get on and flowing.

Because the cabin altitude might peak to very high altitude the crew
masks are pressure breathing masks - that means oxygen is forced into
the lungs at a modest pressure and the crew are specially trained in
their use. This also applied to the VC10 incidentally as its max. cruise
was 43000ft where the medics decided pressure breathing was advisable
although the pressure in the VC10 masks was a little less.

In short the Concorde is provided with the same level of safety as any
other airliner but to meet the requirement required some special
equipment and procedures were necessary because of the higher altitudes
involved. The cabin is provided with two pressure controllers (you will
find only one on all other airliners) and the normal max. differential
pressure is around 10.7 psi which gives a cabin altitude of 6000ft at
60000ft - without any unintended holes (like windows gone!) in the hull.

--
Marc Schaeffer ---- Luxembourg ---- mailto:marcmsc@cmdnet.lu
The   DE HAVILLAND COMET website:       http://surf.to/comet
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