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RE: starship-design: How to build a station.

> -----Original Message-----
> From: L. Parker [mailto:lparker@cacaphony.net]
> Sent: 28 April 2000 04:22
> To: 'Walker, Chris'; 'starship design'
> Subject: RE: starship-design: How to build a station.
> Thanks Chris, but both reactions you just described are bipropellant. The
> catalytic reaction breaks the hydrazine down to liberate a small quantity
> oxygen for use as an oxidizer. The hypergolic reaction uses a mixture of
> hydrazine - typically mono-methyl hydrazine mixed with an oxidizer such as
> nitrogen tetraoxide to produce spontaneous combustion. Although both
> reactions are exothermic, the hypergolic one is much more so. 
> The key word was the last one in your post - decomposition - as opposed to

> combustion.

Hi Lee,

I thought the catalytic reaction was:

3.N2H4  ->  4.NH3 + N2

In otherwords, no oxygen involved (or liberated). I use the term
'monopropellant' here as the hydrazine is the only fuel carried on board
(hence 'one propellant'). AS far as I know, the catalyst bed doesn't
decompose or contribute oxygen atoms to the reaction, so isn't an oxidiser.

As you say, the hypergolic reaction is a bipropellant one; I used this as an
example of hydrazine being used in a bipropellant system to differentiate it
from the monopropellant catalytic reaction.

It may be that we're arguing over semantics here...I define a monopropellant
system as one which uses one fuel only (eg. you only have hydrazine tanks),
a bipropellant system uses both a fuel and oxidiser (eg. your example
above), carried in separate tanks. What would you call a monopropellant?

> I spent many years working with these fuels and acquired a 
> healthy respect and understanding of them, mostly by having the bejeesus 
> scared out of me. You have to be there when the leak check detector turns
purple to
> understand...

Sounds like you've got some good stories there <g>...