On Sun, Jan 26, 2003 at 06:22:12PM -0800, Pierce Nichols wrote:
>         I think that perhaps you are using the wrong number for heat of 
> formation. The number you are using is probably the one that applies when 
> you are reacting H2 with something else, right? The energy of the 
> recombination reaction is equal to the amount of energy required to 
> disassociate H2 into monatomic H (simple conservation of energy). I'm sure 
> that energy is available somewhere.

Hmmm, you would appear to be right, since Clark says that it's around
100 kcal/mol, which is around 418680 J, and I was using 8123 J from the
following table:
<http://members.axion.net/~enrique/propellantheatofformation.html>. I
think I misread what they were saying and assumed that "elemental
molecules" meant the atoms... oh well. So we're actually looking at an
Isp of 1000-1100 seconds and so a chamber temperature of around 3000K,
which is similar to a nuclear rocket  :)

-- 
Sean Lynch http://sean.lynch.tv/

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