Xref: utzoo rec.aviation:13071 sci.space.shuttle:2625
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!ames!amdcad!sun!concertina!fiddler
From: fiddler%concertina@Sun.COM (Steve Hix)
Newsgroups: rec.aviation,sci.space.shuttle
Subject: Re: SR71 to be retired October 1st, rumors regarding SR-71
Message-ID: <94935@sun.Eng.Sun.COM>
Date: 20 Mar 89 20:29:08 GMT
References: <524@gonzo.UUCP> <1475@petsd.UUCP> <13987@elroy.Jpl.Nasa.Gov> <278@cbnewsl.ATT.COM>
Sender: news@sun.Eng.Sun.COM
Lines: 30

In article <278@cbnewsl.ATT.COM>, sw@cbnewsl.ATT.COM (Stuart Warmink) writes:
> In article <320@carroll1.UUCP> dtroup@carroll1.UUCP (Dave Troup) writes:
>>	You are correct, the skin of the '71 looks like a congrued surface. As
>>	the skin heats up during flight, it expands and smoothens out. [...]
> 
> As the wing-span itself won't change much (it is mostly the skin which gets hot),
> the corrugations will actually get bigger as the skin expands!
> Perhaps another reason they exist is to increase the surface area available for 
> radiating the heat away...but then again, more heat will be generated in the first
> place...

(From an article about Kelly Johnson read long ago and far away...)

The corrugated skin on the SR-71 came about when Johnson (or one of his
team) noticed an odd castiron stove with a corrugated surface.

When he asked why it was made that way, the manufacturer said that if
they didn't do it, the sides of the stove would warp as it heated and
cooled...it kept flat sections flat at whatever temperatures.

They were having this same problem at the time with the SR-71's design. 

> Something else to ponder about - the SR71 is very dark coloured, and Concord is 
> white for the same reason: to stay cool, so to speak!

At the time, there were only two paint color available that would stand
the heat expected during the plane's operation.  The XB-70 got white,
the SR-71 got black, and Lockheed spent something like $1M getting a
pint developed that would allow painting US insignia on the aircraft,
and not have to repaint after each flight.  (Or so goes the tale.)