Re: why paint on airliners?

From:         powell@syd.dwt.CSIRO.AU (Powell Heuer)
Organization: CSIRO Div. of Wool Technology, Ryde, Australia
Date:         20 Jan 93 02:39:40 PST
References:   1 2 3
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In article <airliners.1993.64@ohare.Chicago.COM>, pab@po.CWRU.Edu (Pete
Babic) writes:

....

|>Why would a manufacturer insist on paint? Is it because of corrosion?
|>If so,
|>does the quality of the metal differ from aircraft that may be left
|>bare?

The argument I've heard (I don't know how relevant to commercial airliners)
goes thus:
1. Aluminium is a good visible reflector so doesn't absorb much solar
radiation (heat) which has its peak power in the visible.
2. However, as a metal it is also "shiny" in the thermal infra-red and so
doesn't easily radiate the heat that it does absorb.
3. White paint is almost as good a reflector in the visible but is fairly
black in the thermal infra-red and so radiates well the heat that it does
absorb (or is generated internally).
4. A white painted aluminium surface will therefore be cooler in the sun
than an unpainted, polished one.

This may be significant in terms of the air-conditioning load for an
aircraft sitting on the ground in bright sun.

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Powell Heuer                            E-Mail: P.Heuer@syd.dwt.csiro.au
CSIRO Division of Wool Technology
PO Box 7
Ryde NSW 2112 AUSTRALIA