Re: Why are ailiners white? Old vs. New

Date:         21 Nov 97 01:59:55 
From:         j.s.harris@worldnet.att.net (Joel Harris)
Organization: AT&T WorldNet Services
References:   1 2 3
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On 03 Oct 97 01:18:34 , Steve Lacker <look@the.sig> wrote:
>I came across an interesting claim the other day. I've always assumed
>that from the very beginning, jet aircraft airconditioning systems have
>operated on the same principle they do today. Ie, take hot bleed air,
>cool it while still highly pressurized in a heat exchanger, pass it
>through an expander valve so that it expands and gets cold. However, I
>was snooping around Carrier's web site (the air conditioning company)
>and they claimed the following as one of their "firsts":
>
>1955:   With the advent of jet passenger service, Carrier develops an
>        air-turbine-driven centrifugal refrigeration machine to cool the
>        Douglas Aircraft Company's DC 8. Although small enough to fit
>        inside a small piece of carry-on luggage, it was powerful enough
>        to air condition seven average sized homes.

I'm not sure WRT the DC-8's environmental system, but AA's 707 fleet
were equipped with 2 electrically driven air conditioning packs.  I'm
not exactly sure who manufactured them.  I do know that if both packs
were started while the plane was hooked to the ground electrical unit
(which at BNA was a 125 KVA diesel-powered Hobart truck-mounted
generator) it had a bad habit of stalling the GPU.  This was not a
good thing, since a generator bearing locked up one day and promptly
flipped a 3-ton truck that the package was mounted on.  AFAIK, most
everything since the days of the 707 have been equipped with air cycle
machine environmental systems.