Re: aircraft windows

Date:         20 Mar 97 02:38:33 
From:         "Fred Dunlap" <fred@cyrix.com>
Organization: Cyrix
References:   1
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cahill0@ibm.net wrote in article <airliners.1997.636@ohare.Chicago.COM>...
> I'd like to know from what materials aircraft windshields and/or
> canopies are typically made.  Thanks.

Although not really qualified to answer I'll do it anyway.
Some/many/all? Big airliners use multiple sheets of tempered
glass with plastic between the sheets.  This is similar to
your car's windshield.  Cars have two pieces of 1/8 inch (2.5mm)
thick non tempered glass with one sheet of plastic.  747's
have (as I recall) three sheets of tempered 1/4 inch (6mm)
with two layers of plastic. I believe the plastic is the same
as they use on cars but thicker.  They add a conductive coating
to the glass to heat it when needed (controlled by the pilot
I assume).  These windshields have to pass the now famous
chicken test where the manufacture shoots a dead (non frozen)
chicken at the windshield at 400?MPH to show it shouldn't
fail if hit buy a duck/goose in flight.  I've heard tell it
would take about a half an hour to chop through one with a
fire ax.

Smaller planes have smaller (thinner) windshields.  Most of
these are made out of Plexiglas (TM) or Lexan (TM).  These
are normally 1/4 inch and sometime thinner.

Fighter jets use either plastic or glass.  In the case of glass,
they are formed and then chemically tempered.  I have no idea
how they form them.

-- Fred Dunlap fred@cyrix.com