From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of ignacio belieres
Sent: vrijdag 12 augustus 2016 21:39
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: "Direct" Hydrogen Peroxide engines
In those detonations you described, what temperatures did the peroxide
reach? = the decomposition temperature of the mix predicted by the initial
feed temperature, composition and pressure mentioned in literature.
_I hope you ran into those famous H. Walter's Nazi decomposition graphs,
still valid but rare. If you had a butane burner heating the peroxide then
it was to be expected, especially if it was under atmospheric conditions. ,
The inhibitor type and purity matters; Merck's (not so cheap) pro analisi 30
% with pimelic acid inhibitor allows deep enrichment beyond 90 % with
atmospheric evaporation. 50 % quality (to clean pig stables) is not OK for
this procedure and detonates beyond 85 %.
Could you give me some sources on the claim that hypergolic engines lead to
chamber fragmentation? Try Google. Or ask Henry S. who has encyclopedic
literature know-how far beyond mine.
According to >10 years ago Henry S. regarded 14 s delay time too long for
HTP/catalyst doped alcohol fuels. However, John Rusek's engine did work with
such delays. check with Google. We are of course using the latter types of
mixtures you described. I described? which ones? there are hundreds of such
compositions.
jd
_____
From: <mailto:johndom@xxxxxxxxx> johndom@xxxxxxxxx
To: <mailto:arocket@xxxxxxxxxxxxx> arocket@xxxxxxxxxxxxx
Subject: [AR] Re: "Direct" Hydrogen Peroxide engines
Date: Fri, 12 Aug 2016 15:53:42 +0200
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of ignacio belieres
Sent: vrijdag 12 augustus 2016 10:43
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: "Direct" Hydrogen Peroxide engines
Yeah I would guess this comes up ever so often, but I searched the archives
and could only find so little. Because too many emails were lost because of
reorganisations. The amount of literature on H2O2 with Google and USPTO is
vast but rarely useful.
H2O2 can detonate for sure, but only in vapor compositions yes at
temperatures over 100 celsius AND in an enclosed environment. H2O2 is
surreptitious, stabilizer types, metal contact, temperature, pressure . ! It
can detonate in an open tube like hell. I survived detonations of 6 L 85 %
H2O2 in an open glass Erlenmeyer (open air evaporation field tests from a
save distance) on a butane burner. Went whoosh without a bang but temp
sensors had melted and glass stoppers went orbital. My other test was open
air boiling at home with only 10 mL 90 %: that ended in a shocking bang like
a shotgun and a big stink. Wall scrubbing job ensued I would assume the
environment inside even a pre catalyzed biprop engine is harsher, but I
havent heard of an explosion ever happening like that, so it would seem
unlikely for it to do so under liquid-liquid injection. British Stentor HTP
motors had their cat pack exhaust inside the chamber. Simplest and I don't
think they ever exploded. Never read as to why.
We considered using a catalyst bed as many other successful programmes have,
but they tend to take a while to learn run well and are somewhat expensive.
Our experience with permanganate left a lot to be wished for too so the only
option is silver catalysts, which are tricky to use with >90% h2o2.
I mentioned hypergolic ignition because that is what we are aiming for. The
idea is to start the engine with a slug of a fuel that ignites with peroxide
and then switch to kerosene for better isp density. What do you think? It is
often mentioned (like on AR) hypergols are more prone to chamber
fragmentation. A sufficiently short ignition delay matters there. We tested
an engine running on our hypergolic mixture, a small one with only 500 N of
thrust but its objective wasnt raw thrust either. Do you mean ww2
hydrazine/Cu2+ or a dissolved cat salt of the early 2000?
jd
_____
From: <mailto:johndom@xxxxxxxxx> johndom@xxxxxxxxx
To: <mailto:arocket@xxxxxxxxxxxxx> arocket@xxxxxxxxxxxxx
Subject: [AR] Re: "Direct" Hydrogen Peroxide engines
Date: Fri, 12 Aug 2016 09:40:29 +0200
This thread comes up every 5 years or so on arocket, so was often discussed.
Mixtures of gaseous or liquid H2O2 > 80 wt. % have the nasty habit to
detonate when heated and ignited. Add a fuel and the detonation is worse of
course.
To have it deflagrate as a propellant you need to pre-decompose the H2O2,
monopropellant wise, in a controlled manner with a catalyst bed in order to
set free its oxygen as a gas, next spray a fuel in this hot gas. Then it
becomes a bipropellant. Ignition is not necessary as the H2O2 decomposition
gasses are typically hot enough to cause, say, kerosene ignition. Google
Black Arrow launcher. Also the once operational AR2-3 peroxide bipropellant
engine used a catalyst bed:
http://hydrogen-peroxide.us/uses-biprop-combustion/OSC-Peroxide-Propulsion-a
t-Turn-of-Century.pdf.
There are ways to pre-decompose H2O2 thermally which has been done
successfully. But so far it proved complicated compared to the simplicity of
a catalyst bed and never made it for launching anything. As far as I know.
jd
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of ignacio belieres
Sent: vrijdag 12 augustus 2016 8:34
To: arocket@xxxxxxxxxxxxx
Subject: [AR] "Direct" Hydrogen Peroxide engines
Hello everyone,
I have been lurking this list for quite a now,
but not until recently had I read the discussions on peroxide propulsion.
Leaving the supply problems aside, some have expressed doubts about being
able to run a hydrogen peroxide-hydrocarbon rocket engine in a direct mode
without a catalyst bed.
Why is that? Could any of you name some projects
where it was attempted and found to be impossible or too difficult? I know a
lot of you have direct experience with this so I was hoping some of you
might help me clear some doubts. Perhaps a high characteristic length
coupled with hypergolic ignition could work for this application, or not.
Well, I can't wait to see what many of you have to
say.
Cheers,
IB
