Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!sdd.hp.com!wuarchive!gumby!umich!dgsi!gregc
From: gregc@cimage.com (Greg Cronau)
Newsgroups: sci.space
Subject: Re: Fire in Space
Message-ID: <1991Feb5.042519.3206@cimage.com>
Date: 5 Feb 91 04:25:19 GMT
References: <7332@crash.cts.com> <10134@ncar.ucar.edu>
Reply-To: gregc@dgsi.UUCP (Greg Cronau/10000)
Distribution: na
Organization: Cimage Corp, Ann Arbor, MI
Lines: 30

In article <10134@ncar.ucar.edu> strandwg@ncar.ucar.edu (Gary Strand) writes:
>> Dan Gookin
>
>> If figure if you lit a match, it probably would lack the familiar conical
>> shape the flame has here on earth. In fact, I think it would look like a
>> point of light or perhaps a spherical flame.
>
>  Why? What effect does gravity have on the burning particles, relative to
>  the forces they feel from the other heated particles around them? I would
>  think that since gravity plays such a small role in what a flame looks
>  like, it would look the same on the Shuttle (say) as here on earth.
>-- 
>Gary Strand                           There is only one success -- to be able
>Internet: strandwg@ncar.ucar.edu      to spend your life in your own way.
>Voicenet: (303) 497-1336                                 - Christopher Morley

There is a reason that a match flame has a conical shape pointed upwards.
The flame heats the air. Hot air is less dense than cold air, hence an
equal volume of hot air is lighter than the surrounding cold air. This
causes the hot air to rise and the cold air to fall into the space left by
the hot air. This is what makes hot air balloons work.
	WHICH WAY IS *UP* IN ZERO-G?!?!

There is *NO WAY* that a match flame would be conical in zero-g unless
you were waving it around in your hand. The hot air *would* be less dense,
but *gravity* is what makes that less-dense air rise! A flame has just as
much chance burning with a conical shape in zero-g as a flame on earth has
of burning with the flame pointed down or sideways.

gregc@cimage.com