Propane/LOX
Wayne Gramlich
What is the current state of the art with regard to the
Propane/LOX oxidizer/fuel combination? Have there been
any experimental engines? commercial engines?
Thanks in advance,
-Wayne
P.S. To contact me directly replace "NoSpam" with "Wayne".
Henry Spencer
Wayne Gramlich <NoS...@Gramlich.Net> wrote:
>What is the current state of the art with regard to the
>Propane/LOX oxidizer/fuel combination? Have there been
>any experimental engines? commercial engines?
There's been experimental work with that combination and related ones,
but no operational engines.
--
The space program reminds me | Henry Spencer he...@spsystems.net
of a government agency. -Jim Baen | (aka he...@zoo.toronto.edu)
Wayne Gramlich
>
> In article <386A5D73...@Gramlich.Net>,
> Wayne Gramlich <NoS...@Gramlich.Net> wrote:
> >What is the current state of the art with regard to the
> >Propane/LOX oxidizer/fuel combination? Have there been
> >any experimental engines? commercial engines?
>
> There's been experimental work with that combination and related ones,
> but no operational engines.
Are Propane and LOX hypergolic at LOX boiloff temperatures?
The reason for asking is because it may be possible to simplify
the combustion chamber injector plate by premixing the LOX
and propane before injection.
Thanks in advance,
-Wayne
Jonathan A Goff
> Are Propane and LOX hypergolic at LOX boiloff temperatures?
> The reason for asking is because it may be possible to simplify
> the combustion chamber injector plate by premixing the LOX
> and propane before injection.
Highly doubt it. Doesn't LOX boil off well below 0degrees C?
If so that seems like way too low of a temperature for combustion.
Jonathan Goff
"America goes not abroad in search of monsters to destroy. She is the
well wisher to the freedom and independence of all." -- John Q. Adams
Henry Spencer
Wayne Gramlich <NoS...@Gramlich.Net> wrote:
>Are Propane and LOX hypergolic at LOX boiloff temperatures?
No, they aren't. Only the most aggressive fuels, like diborane, are
hypergolic with LOX, and conversely, only the most aggressive oxidizers,
like fluorine, are hypergolic with the (relatively mild-mannered)
hydrocarbons.
There was some work done with FLOX/propane, FLOX being a fluorine/oxygen
mixture. *That* combination is hypergolic, and also gives higher
performance than LOX/propane, at the cost of adding a number of technical
hassles. (One unobvious one is that performance peaks essentially right
at the stoichiometric mixture ratio, which means that performance falls
off very sharply with even small mixture-ratio errors, making injector
design tricky.)
An alternative is to dissolve a trace of O3F2 in the LOX, which makes it
hypergolic with nearly anything (including, unfortunately, many materials
that are compatible with normal LOX).
>The reason for asking is because it may be possible to simplify
>the combustion chamber injector plate by premixing the LOX
>and propane before injection.
Premixing injectors were tried, in the early days; the usual result was
explosions.
Even disregarding that, there is a problem in that LOX and propane are
immiscible at anything like typical rocket mixture ratios. The most you
could do would be a suspension of propane droplets in LOX. (You can
dissolve a little bit of propane in LOX, or vice versa, but not a lot.)
A better approach is to use the propane for regenerative cooling, perhaps
even running an expander cycle for turbine drive, and inject it as a gas.
Gas-liquid injectors give far more efficient mixing than liquid-liquid
designs, because the gas velocity is quite high and that shreds the liquid
streams into droplets very effectively.
Charles R Martin
>
> On Sat, 1 Jan 2000, Wayne Gramlich wrote:
>
> > Are Propane and LOX hypergolic at LOX boiloff temperatures?
> > the combustion chamber injector plate by premixing the LOX
> > and propane before injection.
>
> If so that seems like way too low of a temperature for combustion.
>
> Jonathan Goff
>
> "America goes not abroad in search of monsters to destroy. She is the
> well wisher to the freedom and independence of all." -- John Q. Adams
The problem is that propane is a waxy solid at LOX temperatures....
--
================ Charles R Martin crma...@indra.com =================
"Evil does not naturally dwell in the world, in events, or in people. Evil is
a by-product of forgetfulness, laziness, or distraction: it arises when we
lose
sight of our true aim in life." -- Epictatus
Bruce Dunn
> The problem is that propane is a waxy solid at LOX temperatures....
Actually, no. The propane melting point is 85.5 K, while LOX boiling
point is 90 K or so (depending on exact atmospheric pressure). This
allows a vehicle in which the propane is kept at or near LOX temperature
by thermal contact between the LOX tank and the propane tank.
At 300 K (equatorial launch site temperature), propane has a density of
490 kg/m^3 and an inconveniently high vapor pressure (near ten
atmospheres). When cooled to 90 K, the density increases to 790 kg/m^3,
and the vapor pressure is negligable.
--
Dr. Bruce Dunn
General Astronautics Canada, Vancouver B.C.
http://www.genastro.com/
Reliable, low-cost transportation to low Earth orbit and beyond
Wayne Gramlich
>
[...]
> >The reason for asking is because it may be possible to simplify
> >the combustion chamber injector plate by premixing the LOX
> >and propane before injection.
>
> explosions.
>
> Even disregarding that, there is a problem in that LOX and propane are
> immiscible at anything like typical rocket mixture ratios. The most you
> could do would be a suspension of propane droplets in LOX. (You can
> dissolve a little bit of propane in LOX, or vice versa, but not a lot.)
>
> A better approach is to use the propane for regenerative cooling, perhaps
> even running an expander cycle for turbine drive, and inject it as a gas.
> Gas-liquid injectors give far more efficient mixing than liquid-liquid
> designs, because the gas velocity is quite high and that shreds the liquid
> streams into droplets very effectively.
My question about premixing has been answered. Thanks.
Could I ask a slightly more general question? What was it about
LOX/propane that prevented it from making the transition from
experimental engines to operational engines. Was it the additional
hassle of another cryogenic liquid wasn't worth the hassle? Is
liquid propane at LOX boil off temperatures nasty to work with?
Is that the military was more interested in storable propellants?
Or something else I haven't thought of?
Any insights would be appreciated.
Thanks in advance,
-Wayne
P.S. To reply directly to me, replace "NoSpam" with "Wayne".
Craig D Kossowski
: The problem is that propane is a waxy solid at LOX temperatures....
Not as far as I'm aware. Propane is still liquid at 90K (LOX temerature),
and has the added advantage of being denser than at it's own bp (reduced
tank mass) and having essentially zero vapour pressure (reduced NPSH
requirements).
Sub-cooled Propane/LOX as a propellant is a pet interest of mine, and, if
I remember right, one or two others on the group.
Craig Kossowski.
Doug Goncz
same temperatures and densities. For propane, I'd be looking for a nitric acid
type oxidizer. There are several nitrogen oxygen compounds to be looked at.
The little Bernzomatic welder uses 3 ounces of oxygen at 300 psi, and 14.7
ounces of propane at about 120 psi. Both are mixed at about 5 psi and the
propane tank will last through several oxygen tanks. If you'd like me to
measure the thrust of this torch, I could do that. I have been planning on
buying one for a long time, and might be able to measure such a small thrust. I
measured the thrust of an air amplifier years ago, with useful results.
One might ask what the thrust of a little butane torch is, and get a similarly
small result. I'd like to try and measure such a small thrust. The result might
publish.
http://search.aol.com/dirsearch.adp?query=%2Bpropane+%2Blox+%2Brocket
returns 46 hits...
Yours,
Doug Goncz
Experimental Machinist, Replikon Research ( USA 22044-0094 )
Home Page: http://users.aol.com/DGoncz
"I think you gave me too much change. May I keep it?"
Charles R Martin
>
> Charles R Martin wrote:
>
> > The problem is that propane is a waxy solid at LOX temperatures....
>
> point is 90 K or so (depending on exact atmospheric pressure). This
> allows a vehicle in which the propane is kept at or near LOX temperature
> by thermal contact between the LOX tank and the propane tank.
My mistake -- I allowed having seen solid something-or-other when dumping
propane at the old family propane plant to mislead me. Paul Dietz's theory is
that it was longer-chain hydrocarbons I was seeing.
Henry Spencer
Wayne Gramlich <NoS...@Gramlich.Net> wrote:
>Could I ask a slightly more general question? What was it about
>LOX/propane that prevented it from making the transition from
>experimental engines to operational engines.
Mostly, the fact that the US hasn't built any new major hydrocarbon-fueled
rocket systems since the early 1960s. New fuels were not wanted for the
Saturn lower stages, which were quite adequate development challenges with
familiar fuels. Upper-stage work then and since has concentrated heavily
on hydrogen. And the few substantial in-space maneuvering systems -- the
area where the FLOX/propane work was aimed -- which have been built have
stressed simplicity and low development risk rather than top performance.
Propane doesn't have enough performance advantage over kerosene to make it
compelling for applications where kerosene will do.
In general, nobody has valued the combination of high fuel density,
long-term in-space storability, and high performance enough to finish
developing a new fuel combination whose Isp is inferior to LOX/LH2 and
which does involve cryogenics.
>Is liquid propane at LOX boil off temperatures nasty to work with?
Not particularly. It's a bit more viscous than you might like, and the
very low vapor pressure means that you need some other gas (not air!)
above it to avoid tank collapses, but it's not a big problem.
aRJay
I understand it it releases a lot of energy when burnt with oxygen so I
would assume it would be a likely propellant candidate, I believe it is
also pretty dense.
--
How does a rocket/jet engine work?
"It's not that hard.
Stuff goes in, stuff happens, stuff goes out faster than it came in."
- Ian Stirling
aRJay
Henry Spencer
Charles R Martin <crma...@indra.com> wrote:
>My mistake -- I allowed having seen solid something-or-other when dumping
>propane at the old family propane plant to mislead me. Paul Dietz's theory is
>that it was longer-chain hydrocarbons I was seeing.
Quite likely. Commercial "propane" typically is nowhere near pure C3H8,
it's a mixture of all manner of light hydrocarbons. (For example, in
warmer climates like Mexico, it tends to contain a lot of butane to keep
the vapor pressure down.)
Henry Spencer
aRJay <ro...@escore.demon.co.uk> wrote:
>Just to reveal my appalling ignorance, but what about using acetylene...
People have tried. The problem is that pure liquid acetylene is a
powerful and extremely sensitive explosive. (Commercial acetylene
cylinders store the stuff dissolved in acetone, which is reasonably safe
but unacceptably heavy for rocket applications.)
Quite a bit of work was done in the 1950s with various acetylene
derivatives. Generally they are not very stable in storage, tend to
form impossibly sensitive peroxides on exposure to air, and often are
touchy explosives all by themselves. Methylacetylene is one possible
exception.
Jonathan A Goff
> Just to reveal my appalling ignorance, but what about using acetylene as
> I understand it it releases a lot of energy when burnt with oxygen so I
> would assume it would be a likely propellant candidate, I believe it is
> also pretty dense.
I'm not sure about the density. However, it reacts a little too
vigorously for some people (ie it has a real tendancy to blow up).
Personally, I want to try it with H2O2. However, if you do try
such a thing, make sure you have a huge concrete wall between
you and the test stand.....or a bit of inverse square law....
John Schilling
>Just to reveal my appalling ignorance, but what about using acetylene as
>I understand it it releases a lot of energy when burnt with oxygen so I
>would assume it would be a likely propellant candidate, I believe it is
>also pretty dense.
It's also about as explosively unstable as nitroglycerine. Nobody in
their right mind ever works with bulk acetylene. Typically, you use
a pressurized solution of acetylene in acetone, with the acetone stored
in a metallic sponge to inhibit detonation. Then you allow acetylene to
come out of solution as needed - and *only* as immediately needed.
An acetylene rocket would indeed have spectacular performance, but the
tanks would be prohibitively heavy - you could get some propulsive value
out of the depleted acetone, but the sponge and the pressurized containment
are just dead weight.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
*schi...@spock.usc.edu * for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *
Ian Stirling
>Just to reveal my appalling ignorance, but what about using acetylene as
>I understand it it releases a lot of energy when burnt with oxygen so I
>would assume it would be a likely propellant candidate, I believe it is
>also pretty dense.
It shares the annoying fact with ozone, and a number of other oxidisers/fuels
that release energy when burnt, it can also explode all by it'self, in the
tank.
--
http://inquisitor.i.am/ | mailto:inqui...@i.am | Ian Stirling.
---------------------------+-------------------------+--------------------------
<Squawk> Pieces of eight!
<Squawk> Pieces of eight!
<Squawk> Pieces of eight!
<Squawk> Pieces of eight!
<Squawk> Pieces of eight!
<Squawk> Pieces of nine!
<SYSTEM HALTED: parroty error!>
James Ashton
<ro...@escore.demon.co.uk> wrote:
> Just to reveal my appalling ignorance, but what about using acetylene as
> I understand it it releases a lot of energy when burnt with oxygen so I
> would assume it would be a likely propellant candidate, I believe it is
> also pretty dense.
I believe it's very dangerous and/or difficult to store acetylene in pure
form. The oxy/acetylene rigs used by plummers etc, have the acetylene
dissolved in a liquid (possibly acetone). This solution is obviously not
going to be practical in high performace rocketry due to the great mass of
unwanted liquid.
--
James Ashton VK1XJA System Administrator
http://wwwsyseng.anu.edu.au/~jaa Department of Systems Engineering
Voice +61 2 6279 8675 Research School of Information Sciences and Engineering
FAX +61 2 6279 8688 Australian National University
Email James....@anu.edu.au Canberra ACT 0200 Australia
jakem...@my-deja.com
Ian Stirling <Inqui...@I.am> wrote:
>It shares the annoying fact with ozone, and a number of other
>oxidisers/fuels that release energy when burnt, it can also explode
>all by it'self, in the tank.
At least H2O2 and various hydrazines need better reasons to
explode than "He looked at me funny."
(btw, as long as you're using O3/C2H2, you might as well use O15
for marginally lighter exhaust products... not that I can claim credit
for the idea)
--
Jake McGuire
Sent via Deja.com http://www.deja.com/
Before you buy.
Jonathan A Goff
> At least H2O2 and various hydrazines need better reasons to
> explode than "He looked at me funny."
ROFL! Man, it may be the sleep deprivation speeking,
but that was hilarious....
> (btw, as long as you're using O3/C2H2, you might as well use O15
> for marginally lighter exhaust products... not that I can claim credit
> for the idea)
O15? Never heard of that. Got any web links, or the technical
name or something?
George Herbert
>jakem...@my-deja.com wrote:
>> (btw, as long as you're using O3/C2H2, you might as well use O15
>> for marginally lighter exhaust products... not that I can claim credit
>> for the idea)
>
>O15? Never heard of that. Got any web links, or the technical
>name or something?
It's the mass 15 isotope of Oxygen:
http://www.dne.bnl.gov/CoN/nuc/O/O15.shtml
At Space Access 96, if I recall the date correctly,
John Schilling, Frank Crary and I were talking about
crazy propellant ideas. I forget which of us did which
part of the idea, but it evolved from Ozone (which is a
good but detonatable propellant) to Ozone-15, which is
only 15/16 as heavy and would thus increase Isp a few
percent... but O-15 is not a stable isotope, it has
a half life of around 2 minutes. So we were joking about
the rocket fuel you created in an acellerator and used
RIGHT AWAY. Then it got better, because we realized that
the decay product of O-15 is N-15 (decay via electron
capture) producing molecules of nitrogen dioxide.
It just happens that NO2 is hypergolic with ozone.
Ozone-15 thus is an unstable, detonatable, decaying into
self-hypergolic decay products energetic oxidizer with
a halflife of only 2 minutes. We think that this justifies
claiming O-15 is the craziest propellant possible, and so
far nobody has come up with a better one.
-george william herbert
Retro Aerospace
gher...@retro.com gher...@crl.com
Henry Spencer
Jonathan A Goff <jon...@et.byu.edu> wrote:
>O15? Never heard of that. Got any web links, or the technical
>name or something?
He means an isotope, not a compound. Unfortunately, it's got a very
short half-life...
Greg D. Moore
George Herbert wrote:
> Ozone-15 thus is an unstable, detonatable, decaying into
> self-hypergolic decay products energetic oxidizer with
> a halflife of only 2 minutes. We think that this justifies
> claiming O-15 is the craziest propellant possible, and so
> far nobody has come up with a better one.
You're right George, this has got to be one of the most sick reactions
I've heard of in a LONG time.
I love it.
Simon Bradshaw
Herbert) wrote:
> Jonathan A Goff <jon...@et.byu.edu> wrote:
>
> >O15? Never heard of that. Got any web links, or the technical
> >name or something?
>
> It's the mass 15 isotope of Oxygen:
> http://www.dne.bnl.gov/CoN/nuc/O/O15.shtml
>
> At Space Access 96, if I recall the date correctly,
> John Schilling, Frank Crary and I were talking about
> crazy propellant ideas. I forget which of us did which
> part of the idea, but it evolved from Ozone (which is a
> good but detonatable propellant) to Ozone-15, which is
> only 15/16 as heavy and would thus increase Isp a few
> percent... but O-15 is not a stable isotope, it has
> a half life of around 2 minutes. So we were joking about
> the rocket fuel you created in an acellerator and used
> RIGHT AWAY. Then it got better, because we realized that
> the decay product of O-15 is N-15 (decay via electron
> capture) producing molecules of nitrogen dioxide.
>
> It just happens that NO2 is hypergolic with ozone.
>
> Ozone-15 thus is an unstable, detonatable, decaying into
> self-hypergolic decay products energetic oxidizer with
> a halflife of only 2 minutes. We think that this justifies
> claiming O-15 is the craziest propellant possible, and so
> far nobody has come up with a better one.
And this was after exactly how many beers...? :-)
--
*** Simon Bradshaw ***
To avoid my spam-bucket replace 'filter' with 'simon'
Doug Jones
>
> At Space Access 96, if I recall the date correctly,
> John Schilling, Frank Crary and I were talking about
> crazy propellant ideas. I forget which of us did which
> part of the idea, but it evolved from Ozone (which is a
> good but detonatable propellant) to Ozone-15, which is
> only 15/16 as heavy and would thus increase Isp a few
> percent... but O-15 is not a stable isotope, it has
> a half life of around 2 minutes. So we were joking about
> the rocket fuel you created in an acellerator and used
> RIGHT AWAY. Then it got better, because we realized that
> the decay product of O-15 is N-15 (decay via electron
> capture) producing molecules of nitrogen dioxide.
>
> It just happens that NO2 is hypergolic with ozone.
>
> Ozone-15 thus is an unstable, detonatable, decaying into
> self-hypergolic decay products energetic oxidizer with
> a halflife of only 2 minutes. We think that this justifies
> claiming O-15 is the craziest propellant possible, and so
> far nobody has come up with a better one.
Gee, maybe I helped inspire that nightmare with a post a couple months
earlier in October 95... you pretty much combined every nasty
characteristic possible. Wanna propose an SBIR? You do the theory and pay
for my insurance, I'll blow up the hardware.
From: ran...@earth.usa.net (Doug Jones)
Subject: Re: Liquid Ozone Oxidizer
Date: 04 Oct 1995 00:00:00 GMT
Newsgroups: sci.space.tech
Sea Witch (pn...@columbia.net) wrote:
: As long as we are going to have one highly-unstable propellant, why
: not two? Anyone who knows the equations want to tell me what the Isp
: of O3+acetylene would be? I bet it would be pretty high.
Using the AFAL Isp calculator, I get
CHAMBER PRESSURE = 3000 PSI
C2H2 O3 K TEMP BLK DENS ISP VAC
CHAMBER CHAMBER 500:1 Area ratio
1.000 2.100 4726.5 1.0037 458.66
So, let's see now, we have unstable, explosive, toxic, corrosive, hot
burning, *and* cryogenic counts against this combination. Either
propellant would detonate if it were used in a regeneratively cooled
engine. (Probably even if you just spilled the damn stuff.)
A) Is there any way we can make it radioactive, too?
B) Failing that, could we FLOX it?
C) Have the happy sorts in rec.pyrotechnics heard about *this* lulu?
Sheeesh.
..But ya gotta love that density Isp!
--
Doug Jones (ran...@usa.net)
Scares me and *I'm* fearless! << maybe I should add some exclamation
points
Ah, the memories... I once made a bomb squad cop blanch when I told him
about the joys of frozen acetylene.
--
Doug Jones
Rocket Plumber, XCOR Aerospace
http://www.xcor-aerospace.com
Ian Stirling
>In article <947118461.5466.0...@news.demon.co.uk>,
> Ian Stirling <Inqui...@I.am> wrote:
>>It shares the annoying fact with ozone, and a number of other
>>oxidisers/fuels that release energy when burnt, it can also explode
>>all by it'self, in the tank.
> At least H2O2 and various hydrazines need better reasons to
>explode than "He looked at me funny."
> (btw, as long as you're using O3/C2H2, you might as well use O15
>for marginally lighter exhaust products... not that I can claim credit
>for the idea)
Maybe, are there any commercial suppliers though?
--
http://inquisitor.i.am/ | mailto:inqui...@i.am | Ian Stirling.
---------------------------+-------------------------+--------------------------
If it can't be expressed in figures, it is not science, it is opinion.
-- Robert A Heinlein.
Ian Stirling
>George Herbert wrote:
>> Ozone-15 thus is an unstable, detonatable, decaying into
>> self-hypergolic decay products energetic oxidizer with
>> a halflife of only 2 minutes. We think that this justifies
>> claiming O-15 is the craziest propellant possible, and so
>> far nobody has come up with a better one.
> You're right George, this has got to be one of the most sick reactions
>I've heard of in a LONG time.
Hmm.
What about antimatter contained in C60 molecules?
Wouldn't that be stable at low enough temperatures?
--
http://inquisitor.i.am/ | mailto:inqui...@i.am | Ian Stirling.
---------------------------+-------------------------+--------------------------
"I meant, have you ploughed the ocean waves at all?" Colon gave him a cunning
look. 'Ah, you can't catch me with that one, sir' he said 'Everyone knows
horses sink' -- Terry Pratchett - Jingo
Derek Lyons
>Ozone-15 thus is an unstable, detonatable, decaying into
>self-hypergolic decay products energetic oxidizer with
>a halflife of only 2 minutes. We think that this justifies
>claiming O-15 is the craziest propellant possible, and so
>far nobody has come up with a better one.
>
>
Just for amusement value, what are it's (O15's) emissions? Beta?
Derek L.
------------------------------
Proprietor, Interim Books http://www.interimbooks.com
USS Henry L. Stimson homepage http://www.hurricane.net/~elde/655.html
Derek on Books http://www.interimbooks.com/derek/books/
------------------------------
Doug Jones
Derek Lyons wrote:
>
> Just for amusement value, what are it's (O15's) emissions? Beta?
From the CRC handbook, it's a positron emitter with total energy of 2.76
Mev- so slapping together a quick spreadsheet I get
M 15 g/mol (no time to put atoms together into molecules)
Q 2.760E+06 ev
Q 4.422E-13 J (1 ev = 1.602E-19 J)
thalf 124 s
rate 1.339E+20 events/s-mol
power 5.921E+07 W/mol
power 3.947E+06 W/g
At 4 megawatts per gram of O15 (emitted mostly in gammas), the chemical
nastiness ain't even gonna be noticable...
Eugene Leitl
> It shares the annoying fact with ozone, and a number of other oxidisers/fuels
> that release energy when burnt, it can also explode all by it'self, in the
> tank.
Acetylene in pressurized tanks for welding is stored as solution in
acetone, soaking an inert porous matrix (silica). Both liquid and
solid ozone (dark blue-violet) and acetylene explode upon the
slightest provocation.
I seem to remember reading something about the idea of using atomic
gases (hydrogen?) stored as suspension in liquid He for rocket
fuel. This would seem to be even more foolhardy.
Jonathan A Goff
> I seem to remember reading something about the idea of using atomic
> gases (hydrogen?) stored as suspension in liquid He for rocket
> fuel. This would seem to be even more foolhardy.
I agree. If you want the cheapest way to launch something
to orbit, my opinion is that it will be normal chemical
rockets for quite some time. Most in fact will be using
rather bland "vanilla" propellents like LOX, RP-1, JP-5,
H2O2, and Propane. If you want a really high impulse
system, just go with something nuclear electric. Most of
the other gimmicky ideas are just dumb from a development
standpoint. Rockets as they are now work just fine. All
these ideas about microrockets, really active fuels, mass
driver assists, aircraft assists, the recent one about
the aluminum foam solid, etc are all really pointless.
Rockets work just fine right now, as do such things as
ion drives and hall effect thrusters. There may be better
things in the future, but I think most of the silly ideas
mentioned here don't help.
Not that we shouldn't come up with silly ideas. I think
we should. We just need to ask ourselves the question:
"Is this really going to make space exploration cheaper
or easier?" If not, keep it on the backburner because
maybe it might make sense when combined with another
idea, or even mention it here for fun. Just don't think
that you've solved the world's problems without even
bending metal.
But of course, one of the biggest points here is to have
fun and learn, so maybe I should just shut up and stop
whining.
Henry Spencer
> A) Is there any way we can make it radioactive, too?
Sure, use C14 and tritium in the acetylene. Unfortunately, the isotopes
of oxygen all either are stable or have such ridiculously short half-lives
that there's just no practical way to use them. (You don't want your ozone
tank to have a built-in radioactive heat source...)
> B) Failing that, could we FLOX it?
Sure. People used fluorine as an additive to prevent phase-separation
problems with ozone-oxygen mixtures. You might even be able to use F18
(half-life a little under two hours) to make the oxidizer radioactive
while you're at it.
Nick Maclaren
In article <Pine.GHP.4.21.000109...@leo.et.byu.edu>, Jonathan A Goff <jon...@et.byu.edu> writes:
|>
|> Rockets work just fine right now, as do such things as
|> ion drives and hall effect thrusters. There may be better
|> things in the future, but I think most of the silly ideas
|> mentioned here don't help.
|>
|> Not that we shouldn't come up with silly ideas. I think
|> we should. We just need to ask ourselves the question:
|> "Is this really going to make space exploration cheaper
|> or easier?" If not, keep it on the backburner because
|> maybe it might make sense when combined with another
|> idea, or even mention it here for fun. Just don't think
|> that you've solved the world's problems without even
|> bending metal.
Don't forget "less polluting". This may not be a major problem
at present, but would be with a much larger launch level. But
there is an obvious best candidate for that (oxygen and hydrogen),
and it is already well-studied.
However, pollution is one of the biggest arguments in favour of
the various hook schemes.
Regards,
Nick Maclaren,
University of Cambridge Computing Service,
New Museums Site, Pembroke Street, Cambridge CB2 3QG, England.
Email: nm...@cam.ac.uk
Tel.: +44 1223 334761 Fax: +44 1223 334679
Sean Ellis
}From the CRC handbook, [O-15 is] a positron emitter with total energy of 2.76
}Mev- so slapping together a quick spreadsheet I get
}
}M 15 g/mol (no time to put atoms together into molecules)
}Q 2.760E+06 ev
}Q 4.422E-13 J (1 ev = 1.602E-19 J)
}thalf 124 s
}rate 1.339E+20 events/s-mol
}power 5.921E+07 W/mol
}power 3.947E+06 W/g
}
}At 4 megawatts per gram of O15 (emitted mostly in gammas), the chemical
}nastiness ain't even gonna be noticable...
If that 2.76 MeV doesn't include the annihalation energy of the
positrons (which would get stopped pretty quickly), we can add another
1.22 MeV per positron, which takes us up to 5.681E+06 W/g. Wow.
In short, don't try this at home.
Sean
But remember, I'm not a rocket scientist. I just play one on TV.
Fight spam! Join EuroCAUCE: http://www.euro.cauce.org/
John Schilling
>In article <855bqi$d...@crl3.crl.com>, gher...@crl3.crl.com (George
>Herbert) wrote:
>> Ozone-15 thus is an unstable, detonatable, decaying into
>> self-hypergolic decay products energetic oxidizer with
>> a halflife of only 2 minutes. We think that this justifies
>> claiming O-15 is the craziest propellant possible, and so
>> far nobody has come up with a better one.
>And this was after exactly how many beers...? :-)
None on my part, and I don't think Frank and George had hit the
bar beforehand.
The best forms of craziness come when clever people with their
wits about them deliberately set out to be crazy.
Derek Lyons
>Derek Lyons wrote:
>>
>> Just for amusement value, what are it's (O15's) emissions? Beta?
>
>At 4 megawatts per gram of O15 (emitted mostly in gammas), the chemical
>nastiness ain't even gonna be noticable...
>
Yech!
Henry Spencer
Nick Maclaren <nm...@cus.cam.ac.uk> wrote:
>Don't forget "less polluting". This may not be a major problem
>at present, but would be with a much larger launch level. But
>there is an obvious best candidate for that (oxygen and hydrogen),
>and it is already well-studied.
The "less polluting" aspects of LOX/LH2 are greatly over-hyped. H2O is a
greenhouse gas, H2 is an ozone antagonist. As far as pollution goes,
there's nothing terribly wrong with any fuel combination which doesn't
contain chlorine (as most solids do).
Ken Doyle
have seen it carried in a bucket at -40, which is a balmy 233 K. It was
only lightly boiling, and torches were required to heat the propane tank
enough to produce the pressure and volume we needed. Not the safest thing
I've ever witnessed.
The performance advantage of sub-cooled propane over good old kerosene is
minimal and not worth the handling hassle involved in getting it that cold
except to crazy people. It sounds easy, "just get it in contact with a LOX
tank common bulkhead", but you would need to circulate it in the tank and
you would boil off an awful lot of LOX. Anyone seriously considering
sub-cooled propane as a rocket fuel would be better off using kerosene and
spending their efforts on a higher pressure combustion chamber to get the
Isp up. IMHO
Ken Doyle
unemployed rocket tester and plumber
Bruce Dunn wrote:
> Charles R Martin wrote:
>
> > The problem is that propane is a waxy solid at LOX temperatures....
>
> Actually, no. The propane melting point is 85.5 K, while LOX boiling
> point is 90 K or so (depending on exact atmospheric pressure). This
> allows a vehicle in which the propane is kept at or near LOX temperature
> by thermal contact between the LOX tank and the propane tank.
>
> At 300 K (equatorial launch site temperature), propane has a density of
> 490 kg/m^3 and an inconveniently high vapor pressure (near ten
> atmospheres). When cooled to 90 K, the density increases to 790 kg/m^3,
> and the vapor pressure is negligable.
>
> --
> Dr. Bruce Dunn
> General Astronautics Canada, Vancouver B.C.
> http://www.genastro.com/
> Reliable, low-cost transportation to low Earth orbit and beyond
Nick Maclaren
In article <Fo7ow...@spsystems.net>, he...@spsystems.net (Henry Spencer) writes:
|> In article <85ch8s$9ct$1...@pegasus.csx.cam.ac.uk>,
|> Nick Maclaren <nm...@cus.cam.ac.uk> wrote:
|> >Don't forget "less polluting". This may not be a major problem
|> >at present, but would be with a much larger launch level. But
|> >there is an obvious best candidate for that (oxygen and hydrogen),
|> >and it is already well-studied.
|>
|> The "less polluting" aspects of LOX/LH2 are greatly over-hyped. H2O is a
|> greenhouse gas, H2 is an ozone antagonist. As far as pollution goes,
|> there's nothing terribly wrong with any fuel combination which doesn't
|> contain chlorine (as most solids do).
I don't think that you mean H2O :-)
You may well be correct about the over-hype, but are definitely
wrong about the absence of chlorine being the only constraint!
Please note what I said about a much larger launch requirement;
anything that increases the amount of hydrocarbons, nitrogen
compounds or particulate carbon significantly is a bad idea.
I need to breathe air, even if you don't :-)
Simon Bradshaw
Schilling) wrote:
> fil...@sjbradshaw.cix.co.uk (Simon Bradshaw) writes:
>
> >In article <855bqi$d...@crl3.crl.com>, gher...@crl3.crl.com (George
> >Herbert) wrote:
>
> >> Ozone-15 thus is an unstable, detonatable, decaying into
> >> self-hypergolic decay products energetic oxidizer with
> >> a halflife of only 2 minutes. We think that this justifies
> >> claiming O-15 is the craziest propellant possible, and so
> >> far nobody has come up with a better one.
>
> >And this was after exactly how many beers...? :-)
>
>
> None on my part, and I don't think Frank and George had hit the
> bar beforehand.
>
> The best forms of craziness come when clever people with their
> wits about them deliberately set out to be crazy.
Oh, I *know*.
I wasn't implying that one *has* to be under the influence to come up with
this sort of idea. I just wondered if it came into the category of 'mad
concept arrived at whilst drunk' or the one of 'even madder idea arrived
at whilst quite sober'. Back when I was a member of the Imperial College
Science Fiction Society, we certainly came up with plenty in _both_
categories.
Del Cotter
Nick Maclaren (University of Cambridge, England) wrote:
>he...@spsystems.net (Henry Spencer) writes:
>
>|> Nick Maclaren <nm...@cus.cam.ac.uk> wrote:
>|> >Don't forget "less polluting". This may not be a major problem
>|> >at present, but would be with a much larger launch level. But
>|> >there is an obvious best candidate for that (oxygen and hydrogen),
>|> >and it is already well-studied.
>|>
>|> The "less polluting" aspects of LOX/LH2 are greatly over-hyped. H2O is a
>|> greenhouse gas, H2 is an ozone antagonist. As far as pollution goes,
>|> there's nothing terribly wrong with any fuel combination which doesn't
>|> contain chlorine (as most solids do).
>
>I don't think that you mean H2O :-)
Yes, he does. Water vapour is a much more significant natural
greenhouse gas than carbon dioxide.
That said, the hydrogen and oxygen that go to make the rocket fuel will
have been made from water in the first place, so there's no net effect.
(what makes CO2 such a significant part of the *anthropogenic* contrib-
ution to the greenhouse effect is that we're taking it out of long-term
reservoirs and dumping it in the atmosphere, producing a net short-term
effect on the climate)
--
Del Cotter d...@branta.demon.co.uk
"Choose the Dark Side... now why would I do a thing like that?"
--Obi-Wan Renton
Paul F. Dietz
> The performance advantage of sub-cooled propane over good old kerosene is
> minimal and not worth the handling hassle involved in getting it that cold
> except to crazy people.
The advantage I've heard of propane over kerosene is not
its performance, but rather for cleaning reusable engines.
Propane is easily cleaned from the system after use --
just let it boil off. Residual kerosene is harder to remove.
And you don't want any of that residual kerosene getting
into the oxidizer plumbing.
Paul
Doug Jones
Henry's objection was to water in the stratosphere, where the H2 released
by photolysis of the water is an ozone antagonist. It's not the fact that
the hydrogen gets burned that matters, but that it is deposited above the
stratospheric cold trap.
Commercial quantities of H2 are generally made from water shift reactions
on natural gas, and thus *do* release CO2 into the atmosphere. Oxygen is
extracted from the air, not electrolyzed from water on any significant
scale (that's why it's so cheap).
Direct chemical and physical processes such as water shift and fractional
distillation are *far* cheaper in money, energy, and equipment than
electrolysis can be.
Craig D Kossowski
: That said, the hydrogen and oxygen that go to make the rocket fuel will
: have been made from water in the first place, so there's no net effect.
I was under a distinctly different impression, that the oxygen and
hydrogen were produced by liquification of air and processing of
hydrocarbons, respectively. The latter also argues against the supposed
environmental superiority of H2 over hydrocarbons, the pollution and
fossil fuel usage is just displaced, not eliminated.
Craig Kossowski.
Josh Hopkins
}
} In article <85ch8s$9ct$1...@pegasus.csx.cam.ac.uk>,
} Nick Maclaren <nm...@cus.cam.ac.uk> wrote:
} >Don't forget "less polluting". This may not be a major problem
} >at present, but would be with a much larger launch level. But
} >there is an obvious best candidate for that (oxygen and hydrogen),
} >and it is already well-studied.
}
} The "less polluting" aspects of LOX/LH2 are greatly over-hyped. H2O is a
} greenhouse gas, H2 is an ozone antagonist. As far as pollution goes,
} there's nothing terribly wrong with any fuel combination which doesn't
} contain chlorine (as most solids do).
You missed one other category. The various hydrazines and the nitrogen
tetroxide that tends to get used with them are all quite nasty. True,
their effects are on a more local scale than the global scale of
greenhouse gasses and ozone depleters, but they are still polluters. I
do agree that the environmental distinctions between hydrogen and
hydrocarbons are minimal, particularly when you compare them to the
alternatives.
Josh Hopkins
Robert Lynn
Kerosene suitable for rockets, RP-1 or its Russian equivalent, has to be
refined to remove various species that could harm the engine through
coking in the coolant channels. This makes it more expensive and very
uncommon. I think that Propane is far less susceptible to coking in the
coolant channels than kerosene. IIRC that is the reason Gary Hudson et
al they wanted to use use LOX cooling for the Roton RocketJet engine,
because ordinary kerosene was not suitable for cooling.
Robert
Nick Maclaren
In article <38812F4D...@qnet.com>,
Doug Jones <ran...@qnet.com> writes:
|> Del Cotter wrote:
|> } On Fri, 14 Jan 2000, in sci.space.tech
|> } Nick Maclaren (University of Cambridge, England) wrote:
|> }
|> } >I don't think that you mean H2O :-)
|> }
|> } Yes, he does. Water vapour is a much more significant natural
|> } greenhouse gas than carbon dioxide.
|> }
|> } have been made from water in the first place, so there's no net effect.
|> } ution to the greenhouse effect is that we're taking it out of long-term
|> } reservoirs and dumping it in the atmosphere, producing a net short-term
|> } effect on the climate)
|>
|> Henry's objection was to water in the stratosphere, where the H2 released
|> by photolysis of the water is an ozone antagonist. It's not the fact that
|> the hydrogen gets burned that matters, but that it is deposited above the
|> stratospheric cold trap.
Yes, I took that point, but it wasn't MY point, either! What was
it about never being able to agree, because we were arguing from
different premises? :-)
Ozone antagonists and 'greenhouse gases' are different, and it is
very misleading to call water one of the latter without further
qualification. Yes, it has some such effect, but high-altitude
water also forms ice crystals and reflects a lot of sunlight - i.e.
it is an ANTI-greenhouse effect substance. No, I have no idea of
the relative importance of the two effects for a typical launch.
My other point was that a huge amount of the exhaust gases are
expelled at relatively low altitudes, and end up in the lower
atmosphere. Which most of the posters to this group need to
breathe, though perhaps not all ....
Robert Lynn
Del Cotter wrote:
}
} On Fri, 14 Jan 2000, in sci.space.tech
} Nick Maclaren (University of Cambridge, England) wrote:
}
} >he...@spsystems.net (Henry Spencer) writes:
} >
} >|> Nick Maclaren <nm...@cus.cam.ac.uk> wrote:
} >|> >Don't forget "less polluting". This may not be a major problem
} >|> >at present, but would be with a much larger launch level. But
} >|> >there is an obvious best candidate for that (oxygen and hydrogen),
} >|> >and it is already well-studied.
} >|>
} >|> The "less polluting" aspects of LOX/LH2 are greatly over-hyped. H2O is a
} >|> greenhouse gas, H2 is an ozone antagonist. As far as pollution goes,
} >|> there's nothing terribly wrong with any fuel combination which doesn't
} >|> contain chlorine (as most solids do).
} >
} >I don't think that you mean H2O :-)
}
} Yes, he does. Water vapour is a much more significant natural
} greenhouse gas than carbon dioxide.
}
} That said, the hydrogen and oxygen that go to make the rocket fuel will
} have been made from water in the first place, so there's no net effect.
} (what makes CO2 such a significant part of the *anthropogenic* contrib-
} ution to the greenhouse effect is that we're taking it out of long-term
} reservoirs and dumping it in the atmosphere, producing a net short-term
} effect on the climate)
Which is why we should be promoting landfills. We should each take time
out from our busy schedules to go out and cut down a few hectares of
forest and bury it good and deep. That solves the CO2 problem :).
The biggest problem with rockets and aircraft is that most of their
exhaust products end up in the the stratosphere, where they tend to have
longer residence times. To have no effect at all on the stratosphere
the only solution is to use nuclear or beamed power to provide the heat
and use air as the working fluid in the propulsion system. Not that I
would advocate such extreme measures. In the end rockets are irrelevant
compared to commercial aircraft.
Robert
Doug Jones
}
} "Paul F. Dietz" wrote:
} > The advantage I've heard of propane over kerosene is not
} > its performance, but rather for cleaning reusable engines.
} > Propane is easily cleaned from the system after use --
} > just let it boil off. Residual kerosene is harder to remove.
} > And you don't want any of that residual kerosene getting
} > into the oxidizer plumbing.
}
} Kerosene suitable for rockets, RP-1 or its Russian equivalent, has to be
} refined to remove various species that could harm the engine through
} coking in the coolant channels. This makes it more expensive and very
} uncommon. I think that Propane is far less susceptible to coking in the
} coolant channels than kerosene. IIRC that is the reason Gary Hudson et
} al they wanted to use use LOX cooling for the Roton RocketJet engine,
} because ordinary kerosene was not suitable for cooling.
LOX cooling did work quite well, even when the combustion chamber had a
significant crack which allowed cold oxygen to leak into the chamber
through the wall. LOX can't coke even when abused :) (For the RocketJet
engine, LOX cooling was required due to the LOX having the greater pressure
budget available for cooling, as well as having more enthalpy available to
cool the combustors.)
On the other hand, the only processing needed to make propane low-fouling
is to subcool it once to around 95 K- the higher hydrocarbons and sulfur
compounds freeze out; the sulfur is the real problem and low sulfur
kerosene doesn't foul badly either, so probably the best solution is to pay
the refinery extra to clean it up. Environmental protection laws are
driving toward low-sulfur diesel and jet fuels, so the desulfurization
equipment will be amortized over a much larger user base. This may end up
being the simplest solution.
On the gripping hand, the most annoying thing about kerosene for reusable
engines is the cleanup- soot, sludge, and oil get onto and into
*everything* and getting it our of the oxygen system ain't easy. This I
know from personal experience, and volatile zero-residue fuels in general
are attractive because of it.
Jens Lerch
}"Paul F. Dietz" wrote:
}> The advantage I've heard of propane over kerosene is not
}> its performance, but rather for cleaning reusable engines.
}> Propane is easily cleaned from the system after use --
}> just let it boil off. Residual kerosene is harder to remove.
}> And you don't want any of that residual kerosene getting
}> into the oxidizer plumbing.
}Kerosene suitable for rockets, RP-1 or its Russian equivalent, has to be
}refined to remove various species that could harm the engine through
}coking in the coolant channels. This makes it more expensive and very
}uncommon. I think that Propane is far less susceptible to coking in the
}coolant channels than kerosene. IIRC that is the reason Gary Hudson et
}al they wanted to use use LOX cooling for the Roton RocketJet engine,
}because ordinary kerosene was not suitable for cooling.
Many Russian/Soviet rocket engines already use LOX as coolant, thus they
can use quite standard kerosene, at least compared to RP-1.
--
We think one of these days the US ought to | Jens Lerch
have a permanent space station up, and the | jle...@geocities.com
Space Shuttle will allow us to do it for one- | http://jens.lerch.home.pages.de
tenth the cost. - Astronaut John Young, 1981 | back-online
Del Cotter
Doug Jones <ran...@qnet.com> (Space) wrote:
>} Yes, he does. Water vapour is a much more significant natural
>} greenhouse gas than carbon dioxide.
>}
>} That said, the hydrogen and oxygen that go to make the rocket fuel will
>} have been made from water in the first place, so there's no net effect.
>} (what makes CO2 such a significant part of the *anthropogenic* contrib-
>} ution to the greenhouse effect is that we're taking it out of long-term
>} reservoirs and dumping it in the atmosphere, producing a net short-term
>} effect on the climate)
>
>Henry's objection was to water in the stratosphere, where the H2 released
>by photolysis of the water is an ozone antagonist. It's not the fact that
>the hydrogen gets burned that matters, but that it is deposited above the
>stratospheric cold trap.
I don't understand why you're telling me this, since I made no comment
at all on Henry's statement that H2 is an ozone antagonist.
mlin...@my-deja.com
he...@spsystems.net (Henry Spencer) wrote:
> In article <ftnPfAAW...@escore.demon.co.uk>,
> aRJay <ro...@escore.demon.co.uk> wrote:
> >Just to reveal my appalling ignorance, but what about using
acetylene...
>
> People have tried. The problem is that pure liquid acetylene is a
> powerful and extremely sensitive explosive. (Commercial acetylene
> cylinders store the stuff dissolved in acetone, which is reasonably
safe
> but unacceptably heavy for rocket applications.)
>
> Quite a bit of work was done in the 1950s with various acetylene
> derivatives. Generally they are not very stable in storage, tend to
> form impossibly sensitive peroxides on exposure to air, and often are
> touchy explosives all by themselves. Methylacetylene is one possible
> exception.
In addition to that, Bob Zubrin once proposed an airbreathing National
Aerospace Plane type HTHL SSTO that would have used acetylene fuel! His
solution was to carry liquid methane & oxygen to reduce the size of the
propellant tanks. The vehicle would produce acetylene in flight so
there would be no need to store it. I strongly suspect this is a case of
having a "solution searching for a problem," though.
---
The details can be found in "Methane-Acetylene Cycle Aerospace Plane"
by Robert Zubrin, published in JBIS 1994, p.241.
MARCU$
Henry Spencer
Craig D Kossowski <3c...@qlink.queensu.ca> wrote:
>: That said, the hydrogen and oxygen that go to make the rocket fuel will
>: have been made from water in the first place, so there's no net effect.
>
>hydrogen were produced by liquification of air and processing of
>hydrocarbons, respectively. The latter also argues against the supposed
>environmental superiority of H2 over hydrocarbons, the pollution and
>fossil fuel usage is just displaced, not eliminated.
The hydrogen enthusiasts tend to compare today's hydrocarbon usage against
hypothetical future methods of hydrogen production. As others have
already noted, yes, hydrogen is currently made from hydrocarbons.
Henry Spencer
Josh Hopkins <hop...@dimensional.com> wrote:
>} ...As far as pollution goes,
>} there's nothing terribly wrong with any fuel combination which doesn't
>} contain chlorine (as most solids do).
>
>tetroxide that tends to get used with them are all quite nasty. True,
Exactly; those compounds are too unstable to persist very long after use.
From the pollution point of view, they're a relatively minor problem.
They're bad choices in other ways, but their pollution problems are not
serious.
Mind you, I should probably have qualified my comments by saying "any
*current* fuel combination". Fluorine-based oxidizers are another can
of worms.
Ken Doyle
this concern justifies using propane over kerosene.
At RRC we didn't cool with LOX in order to be able to use kerosene; cooling with
LOX for other reasons just eliminated the coking concerns of using cheaper and
readily available kerosene/Jet A.
Ken Doyle
Robert Lynn wrote:
> "Paul F. Dietz" wrote:
> >
> > Ken Doyle wrote:
> >
> > > The performance advantage of sub-cooled propane over good old kerosene is
> > > minimal and not worth the handling hassle involved in getting it that cold
> > > except to crazy people.
> >
> > The advantage I've heard of propane over kerosene is not
> > its performance, but rather for cleaning reusable engines.
> > Propane is easily cleaned from the system after use --
> > just let it boil off. Residual kerosene is harder to remove.
> > And you don't want any of that residual kerosene getting
> > into the oxidizer plumbing.
>
> Kerosene suitable for rockets, RP-1 or its Russian equivalent, has to be
> refined to remove various species that could harm the engine through
> coking in the coolant channels. This makes it more expensive and very
> uncommon. I think that Propane is far less susceptible to coking in the
> coolant channels than kerosene. IIRC that is the reason Gary Hudson et
> al they wanted to use use LOX cooling for the Roton RocketJet engine,
> because ordinary kerosene was not suitable for cooling.
>
> Robert
Henry Spencer
Nick Maclaren <nm...@cus.cam.ac.uk> wrote:
>You may well be correct about the over-hype, but are definitely
>wrong about the absence of chlorine being the only constraint!
>Please note what I said about a much larger launch requirement;
>anything that increases the amount of hydrocarbons, nitrogen
>compounds or particulate carbon significantly is a bad idea.
The cars people drive to the launch site are likely to be more of a
problem for hydrocarbons and carbon than any reasonable rocket system.
You won't find any noticeable amount of unburned hydrocarbons in a rocket
exhaust -- that's strictly a problem of reciprocating engines.
Particulate carbon is a bit more of an issue, but not a large one,
especially with modern high-pressure engines with a lean mixture ratio.
Again, existing sources are likely to be far more important; no reasonable
launch rate will make rockets a significant contributor.
As for nitrogen compounds, *any* hot rocket exhaust -- yes, even the
sainted LOX/LH2 exhaust -- hitting air will make nitrogen oxides. And
that's about the only nitrogen compound you're likely to find in rocket
exhaust; hydrazine, ammonia, and the like burn much too easily to show
up in the exhaust.
Henry Spencer
Paul F. Dietz <di...@interaccess.com> wrote:
>The advantage I've heard of propane over kerosene is not
>its performance, but rather for cleaning reusable engines.
>Propane is easily cleaned from the system after use --
Propane's low boiling point also lets you do some other useful things --
e.g. converting it to a gas via chamber cooling, so you can inject it as a
gas -- which are normally thought of as hydrogen specialties. (Injecting
one propellant as a gas is a big win, because that lets you spray the
other one into a high-velocity gas stream, which gives better and faster
mixing than conventional liquid/liquid injection.)
Nick Maclaren
In article <FoL8z...@spsystems.net>, he...@spsystems.net (Henry Spencer) writes:
|> In article <85n64g$ma6$1...@pegasus.csx.cam.ac.uk>,
|> Nick Maclaren <nm...@cus.cam.ac.uk> wrote:
|> >You may well be correct about the over-hype, but are definitely
|> >wrong about the absence of chlorine being the only constraint!
|> >Please note what I said about a much larger launch requirement;
|> >anything that increases the amount of hydrocarbons, nitrogen
|> >compounds or particulate carbon significantly is a bad idea.
|>
|> The cars people drive to the launch site are likely to be more of a
|> problem for hydrocarbons and carbon than any reasonable rocket system.
At present, that is unquestionably true.
|> You won't find any noticeable amount of unburned hydrocarbons in a rocket
|> exhaust -- that's strictly a problem of reciprocating engines.
I would be happier with the first half of your statement if it
weren't for the second half, which is NOT true! Some jets do, too.
The point isn't necessarily that current designs produce them, but
that not producing too much of them is a constraint.
|> Particulate carbon is a bit more of an issue, but not a large one,
|> especially with modern high-pressure engines with a lean mixture ratio.
|> Again, existing sources are likely to be far more important; no reasonable
|> launch rate will make rockets a significant contributor.
Not even if we were talking about serious amounts of commercial
traffic into space - perhaps even including widespread tourism - as
was once stated as likely to happen by the end of the 20th century?
Oh, come now. I remember when the same was said about commercial
aircraft - a mere few decades ago.
|> As for nitrogen compounds, *any* hot rocket exhaust -- yes, even the
|> sainted LOX/LH2 exhaust -- hitting air will make nitrogen oxides. And
|> that's about the only nitrogen compound you're likely to find in rocket
|> exhaust; hydrazine, ammonia, and the like burn much too easily to show
|> up in the exhaust.
That is true. And nitrogen oxides are not a huge problem in small
quantities, as they come out in the rain and form fertiliser :-)
But that is true of small quantities - the problems with most such
things is when they get out of hand.
Yes, I take your point that currently such things are not an issue,
but it doesn't mean that they aren't constraints, if one were
considering a much larger launch requirement, such as would be
needed for serious amounts of industry in space.
Doug Jones
> |> exhaust -- that's strictly a problem of reciprocating engines.
>
> I would be happier with the first half of your statement if it
> weren't for the second half, which is NOT true! Some jets do, too.
> The point isn't necessarily that current designs produce them, but
> that not producing too much of them is a constraint.
While hydrocarbon fueled engines do typically run rich, the hydrocarbons
*are* fully decomposed, and any carbon in the exhaust condenses from the
equilibrium mixture, not from pyrolised fuel. Most of this carbon
afterburns in the plume anyway as it mixes with air.
Gas generator engines such as the F-1 do crank out unburned hydrocarbons
from the absurdly rich (0.4:1 O:F) turbine exhaust. Staged combustion
engines like the RD-170 don't have this problem.
Running at higher O:F (about 2.8:1) eliminates even the carbon from the
exhaust, with little reduction of Isp and a significant improvement in bulk
density. It also makes for a really cool looking purple plume :)
Jonathan A Goff
> Propane's low boiling point also lets you do some other useful things --
> e.g. converting it to a gas via chamber cooling, so you can inject it as a
> gas -- which are normally thought of as hydrogen specialties. (Injecting
> one propellant as a gas is a big win, because that lets you spray the
> other one into a high-velocity gas stream, which gives better and faster
> mixing than conventional liquid/liquid injection.)
Yet another reason why I like Hydrogen Peroxide. The
only difference is that the HTP gas is hot enough to
combust with any fuel.....thus making things easier....
Oh well, I'm thoroughly biased.
Jonathan Goff
"America goes not abroad in search of monsters to destroy. She is the
well wisher to the freedom and independence of all." -- John Q. Adams
A.J. Libby
the nozzle tubing because of the corrosive action of hot O2 or
present other problems? If cooling with H2O2, does it decompose
into O2 and H2O while still in the tubing and present similar
problems?
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NicholasH1
50s.
Nicholas
Jeff Greason
news:34528fe6...@usw-ex0104-025.remarq.com...
> Does cooling with LOX require any exotic/expensive alloys for
> the nozzle tubing because of the corrosive action of hot O2 or
> present other problems?
It requires oxidation-resistant materials, but these days those need
not be particularly "exotic" or "expensive" -- you just have to
do the necessary engineering work.
> If cooling with H2O2, does it decompose
> into O2 and H2O while still in the tubing and present similar
> problems?
Again, materials choice has to be appropriate. Also, cooling
with a monopropellant can pose problems in certain applications
where rapid engine cutoff is required, since leaving propellant
in the cooling passages post-shutdown isn't a good idea. However
it's been done, and no insuperable problems were found as long
as the design was done right.
----------------------------------------------------------------
"Limited funds are a blessing, not Jeff Greason
a curse. Nothing encourages creative President & Eng. Mgr.
thinking in quite the same way." --L. Yau XCOR Aerospace
<www.xcor-aerospace.com> <jgre...@hughes.net>
wm...@my-deja.com
offhand is that you have a lot of hydrogen in the CH4 molecule and LNG
is a lot more dense than LH. IIRC you have a oxidizer/fuel mix ratio
of 3.45 and an average propellant density of 802 kg/m^3. Specific
impulse of about 390 sec? Assuming 40:1 expansion from 1000 psia. Its
getting fuzzy here. Cool chamber temperature though - relatively
speaking. Hmm...
I recall a mental image of a booster module I designed with this.
Lessee...
180 cubic meters, 150,000 kg of propellant. Total vehicle mass 165,000
kg. Total thrust 225,000 kg force.
I recall an old Rocketdyne Aerospike engine design at the base of a 3.6
m diameter cylindrical that has spherical end caps. The whole tank is
21.6 meters long with a bulk head pointing up 5.1 meters up along the
cylinder length. The lower portion contains LNG and the upper LOX.
The join line between the bulkhead and cylinder is canted at about 4
degrees to let the LOX drain into a side mounted line. The LNG comes
out of the bottom of the bottom spherical end cap. The top is covered
with a slim tapering cone. The base has a pie shaped aerospike
nozzle. There are 12 elements in the spike arranged like slices in a
pie. Each has its own propellant feed system. So, differential thrust
can be applied without gimballing. This makes things simple.
You put 7 of these together in my famous 7-up configuration to launch
big payloads. I seem to recall you could put about 100,000 kg into LEO
with this. Nearly the same as Apollo.
Using my cool fully reusable moonship design (LNG has a longer storage
life than LH, and is denser), you can put 12,000 kg IIRC on the moon
and return it to Earth, and recover all components.
This version of that rocket used ballistic recovery methodology instead
of wings. The base of the ballistic cone of both the cislunar and
lunar orbiter modules were aerospike engines which doubled as module
TPS. The LEM still used small tip mounted rockets without TPS.
LOX and LNG are industrial gases that are readily available and cheap.
The methane can be easily reformulated to generate hydrogen which cna
run fuel cells and scrub CO2 out of the air.
* * *