Re: Why are all airliners white?

Date:         16 Sep 97 02:35:27 
From:         Steve Lacker <look@the.sig>
Organization: Applied Research Laboratories - The University of Texas at Austin
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k_ish wrote:
> True.  IIRC, the Concorde is white instead of the BA gray due to solar
> heat loading as well as the high skin temperatures generated by
> aerodynamic friction.

Only half true, the other half is false. White paint does indeed reduce
the absorption of heat from the sun, but by the same token it *reduces*
the ability of the plane to radiate heat away. When a major source of
heating is aerodynamic friction, the only way to shed this heat is by
radiation. The best color to effectively radiate heat is *black* (the
same principles that determine how much heat a colored surface absorbs
determine how much it will radiate). This is a major part of why the
SR-71 is black- to radiate as much heat as possible. Of course, that
still isn't enough to cool all the avionics and shed the friction
generated heat, which is why Blackbirds drink their fuel "on the rocks"
:-)

--
Stephen Lacker
Applied Research Laboratories, The University of Texas at Austin
PO Box 8029, Austin TX 78713-8029
512-835-3286	slacker@arlut.utexas.edu