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From: pcf@drux3.UUCP (FryPC)
Newsgroups: net.sci,net.space
Subject: Re: Would a candle burn ...
Message-ID: <1329@drux3.UUCP>
Date: Fri, 26-Jul-85 13:56:44 EDT
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Posted: Fri Jul 26 13:56:44 1985
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Xref: watmath net.sci:391 net.space:4345

> ... in space?
> 
> This question came up the other day in discussion.  We seemed to think
> that there would be problems because in the absence of a gravity field
> the heated air would not rise.  Thus CO2 would not be pulled away from
> the area of burning and O2 would not be pulled in.  Therefore
> combustion would not be continuous.

I do not think that the O2/CO2 supply is the problem. In a 'theoretical'
still air, there is no O2, the candle can not burn, but in any 'real' (sic)
environment, there should be enough air movement to keep combustion going.

I think there are other problems:-

My understanding of how a candle works, once it is burning in normal G:

	The heat from the flame melts the solid wax.
	Capilliary action draws the molten wax up the wick.
	Increased heat vaporises the molten wax.
	The vapor burns using oxygen and producing CO2 H2O etc.

Only the vapour is flammable, the non-flammable liqud wax forming a pool
around the base of the wick stops the flame from going in that direction
and melting the wax faster than it can be burned.

In zero G:

	The heat from the flame melts the solid wax.
	Capilliary action draws some of the molten wax up the wick the
		rest floats off.
	Increased heat vaporises the molten wax.
	The vapor burns using oxygen and producing CO2 H2O etc.

The flame would burn in all directions, the pool of melted wax would
not remain to stop the flame from travelling along the wick so the
candle would soon turn itslef into floting blobs of hot/liquid wax.

My theory:
	The candle burns, but not for long and is very messy.

Experiment:
	Take two candles, light them both.
	Invert one of the candles.
	Observe how they burn.
	Average the results.

Peter Fry
drux3!pcf

P.S. All this is, of course, wild speculation from a position of inteligent
     ignorance.