[AR] Re: "Direct" Hydrogen Peroxide engines ... Re: Issues with operating at low chamber pressure
- From: Henry Spencer <hspencer@xxxxxxxxxxxxx>
- To: Arocket List <arocket@xxxxxxxxxxxxx>
- Date: Tue, 6 Sep 2016 13:52:22 -0400 (EDT)
On Tue, 6 Sep 2016, John Dom wrote:
I do not recall a modern engine using a undiluted hydrazines mix as its
hypergolic fuel, next to HTP as oxidizer_ thereby eliminating the presence
of the cat pack complication.
Under modern rules, hydrazines add enough handling worries that people are
reluctant to use them unless storability is important, and people worried
about storability don't like peroxide because of its need for regular
venting.
About the Nazi Messerschmitt 163B rocketplane was written pure hydrazine
could not be used because the combustion temperature of that combo proved
too high. Instead they added alcohol and hydrate water (as N2H2.H2O) in
those inventive days.
They didn't so much add water in hydrate, as not try to get rid of it --
hydrazine hydrate is what the usual manufacturing processes produce, I
believe, and you have to do extra work to get anhydrous hydrazine. They
also added more water with the methanol.
The original reason for adding some methanol (and accepting some water)
may have been cooling, but a later reason was that hydrazine hydrate was
increasingly hard to get, while methanol was plentiful. The percentage of
hydrazine in the Me-163 fuel declined steadily with time.
Related: I also wonder how SpaceX managed to make its Falcon 9 first stage
LOX/kerosene propellants restartable. A game changer which was poorly
commented on. Were extra TEAB capsules (like in the Atlas ICBM) used?
They reportedly have a separate TEA/TEB injection system for ignition;
frozen igniter plumbing was blamed for the 2013 second-stage restart
failure.
Henry
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