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From: maxwell@speedy.DEC
Newsgroups: net.space
Subject: A candle burning in Zero-G....
Message-ID: <3322@decwrl.UUCP>
Date: Sat, 27-Jul-85 12:49:58 EDT
Article-I.D.: decwrl.3322
Posted: Sat Jul 27 12:49:58 1985
Date-Received: Sun, 28-Jul-85 06:23:11 EDT
Sender: daemon@decwrl.UUCP
Organization: DEC Engineering Network
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As I recall, there have actually been tests to see what happens to a burning
candle in Zero-G.

Although I  don't remember the source, I do recall reading about a test in a
plane  'falling'  through a parabola for 30 seconds or so, just before which
the  pilot  had lit a candle. During the beginning of the Zero-G period, the
candle's  flame  rounded  into  a sphere, which got smaller and smaller. The
flame  soon went 'out'. When gravity 'returned' however, the flame returned,
for all appearances reversing its disappearing act.

The offered  explanation  of  the  phenomenon (as I recall, don't hold me to
this)  was  that  the absence of gravity prevented the differentation of the
gasses  involved (both fuel and by products); gravity allows hotter, lighter
gasses  to  leave  (CO2,  H2O,  etc.),  and  cooler,  denser gasses to enter
(vaporized fuel). Unable to rid itself of the useless byproducts, and unable
to  get enough fuel, the flame dies. However, during the buring, a number of
free radicals (transition products) are produced that, when gravity returns,
can 'continue' combustion.

-+- Sid Maxwell