Steam Rockets

Wayne Throop wrote:
: "tomcat"
: Increasing the temperature of water into a super heated steam decreases
: the amount of energy required to crack the water molecule. So,
: regenerative cooling with either the water engine itself, or some other
: rocket engine, reaps big dividends.
:
: But I am not a purist. If lithium aluminum hydride works then it would
: make sense to use it. I am even beginning to think of 'water bombs'
: for the military.

Is this like the "dihydrogen monoxide is toxic" schtick?
'cause it doesn't really make sense otherwise.


Wayne Throop http://sheol.org/throopw




Put the water in the center of the bomb. Surround it with a layer of
lithium aluminum hydride. Surround the LAH with high explosives.

It ought to go "Bang".


tomcat

(Wayne Throop) wrote in :


Is this like the "dihydrogen monoxide is toxic" schtick?
'cause it doesn't really make sense otherwise.

This is tomcat.

Very little of what he says makes any sense. Accept it and
move on.

--Damon

Damon Hill wrote:

(Wayne Throop) wrote in :


Is this like the "dihydrogen monoxide is toxic" schtick?
'cause it doesn't really make sense otherwise.

This is tomcat.

Very little of what he says makes any sense. Accept it and
move on.

I recognized that months ago. From what I've seen quoted by others,
much of what tomcat says that *does* make sense is still wrong, or at
least incomplete to the point of being useless.

::: Is this like the "dihydrogen monoxide is toxic" schtick? 'cause it
::: doesn't really make sense otherwise.

: Alan Anderson
: From what I've seen quoted by others,
: much of what tomcat says that *does* make sense is still wrong, or at
: least incomplete to the point of being useless.

Yah, but characterizing water as a "dense fuel"
sounds more like an intentional parody than a mistake.
And all the details about how to crack it and burn it on the fly
much like all the specious statistics about dihydrogen monoxide toxicity.

Which I suppose fits right in; rocket fuels are often toxic.


Wayne Throop http://sheol.org/throopw

On Sat, 05 Aug 2006 23:19:07 GMT, (Wayne Throop)
wrote:

:-)= dihydrogen monoxide

Dihydrogen monoxide, HH-O or iso-oxydihydride, O-HH, are toxic, ohh,
like an after thought. It is the hydrogen hydroxide, H-OH, isomer
that is as safe as water can be which ain't 2 safe 'round these parts.
I play it safe and only consume C2-H5 -OH, although some guy from
Jackson, Georgia, USA and his classmates discovered the therapeutic
benefits of C2-H5 -O- C2-H5, but that stuff always makes me drowsy so
I stay away from it.

HTH

--
Posted via a free Usenet account from http://www.teranews.com

DougC wrote:

tomcat wrote:
The liquid hydrogen and lox take up too much room and will, over a
period of time, vent into the vacuum of Space.

My space ship doesn't have leaks like that.

The hydrogen and oxygen
can, however, be carried into space as a very dense stable fuel in the
form of water. But the water must be vaporized and the water molecules
cracked apart into separate hydrogen and oxygen atoms.

Toss in a handful of Lithium Aluminum Hydride ( LAH )

How many kg of LAH does it take to split 1 kg of water?

Since the weight of the water will be the same regardless of whether its
stored as H2 and LOX or water, the only offsetting weight savings will
be the elimination of the cryogenics necessary for the former.

--
Paul Hovnanian
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Danny Dot
www.mobbinggonemad.org


"tomcat" wrote in message
oups.com...
The idea of using water as a rocket fuel seems extraordinary, but it is
feasible for at least part of a rocket's propulsion.

Steam vapor is an invisible vapor that has 1600 times the volume of the
water it came from. This fact was used to drive steam locomotives. It
works.

For a rocket, however, the 'trick' is to instantly produce the steam in
an explosive kind of way. If possible this will produce considerable
thrust. Steam locomotives used a fire box burning coal. To
'instantly' produce steam, however, the old 'fire box' of the steam
locomotives is simply too slow.

Now you may wonder why you would want to carry water instead of
previously separated hydrogen and oxygen. Hydrogen and oxygen are very
high volume gases and even as liquids they take up lots and lots of
room. It is difficult to to take enough along in specially made
cryogenic tanks to be effective. These tanks, moreover, have vents
which vent off the gas produced by relatively warm tanks. And this, of
course, is waste and reduces the amount of fuel. It makes hydrogen/lox
a difficult fuel to use for long missions.

Water, on the other hand, is very stable and very dense. It will stay
put for very long voyages and can actually be replenished in Outer
Space. The Moon, for example, is believed to have more than 600
billion tons of water on it's North and South Poles. Asteroids also
have been proven to have water in large quantities. The rings of
Saturn and the Poles of Mars are other examples of water in Outer
Space.

So, the possibility of a 'Steam Rocket' is an exciting one filled with
the promise of a stable, dense, and replenishable fuel.

The 'trick', however, is to instantly vaporize the water into steam in
order to produce enough reaction. The faster the vaporization the
greater the ISP and pounds of thrust.

Interesting idea. Water on a nuclear core would certainly make a good
rocket.

ISP is only a function of the velocity of the gases as they escape the
nozzle. Higher temperatures lead to higher velocities, as does lower
molecular weight of the exhaust gas. This is why a LOX/H2 rocket has a
higher ISP than a kerosene/LOX -- water is a lighter molecule than the
combustion products of kerosene/LOX.

When I first became an astronaut instructor in 1990, I was shocked to find
out the orbit engines on the shuttle (and most other orbit vehicles) do not
use pumps. The roughly 250 psi pressure in the tanks feeds propellant
straight into the 125 psi combustion chamber. This keyed my research into
ISP and I discovered a small chamber pressure does NOT mean low ISP. I also
discovered that ISP in the shuttle computer software is "defined" as VEX,
which is the exhaust velocity of the SSMEs. The Russians talk exhaust
velocity a lot and use the term ISP less than we do.

You are correct that water can be stored in a much smaller tank than
hydrogen, but for a heat engine that dumps a liquid onto a heat sorce, the
small molecular weight of H2 gives much higher escape velocities for the
same temperature. H2 has a molecular weight of 2 and water a weight of 18.
At the same temperature H2 will have a HUGE advantange on ISP/VEX. And, I
see the max temperature for both would be about the same.

BUT, having said this, H2 takes HUGE volume to store, can't be stored on
orbit, requires major engineering to "handle", requires expensive components
to "handle", and is expensive. Maybe water dumped on a nuclear reactor has
its place in the world. It could probably get to SSME like ISPs because in
both cases the exhaust gases are both water. The question is -- can a
nuclear core go to the same temperature of the combusion chamber of an SSME.
If the heat engine design could get to the same temperatures, it would be
easy to get to SSME ISPs. If the design was orbit only, then higher ISP
would be easy because the SSME nozzles are compromized to work at sea level
as well as a vaccum.


A couple of ideas to produce this instantaneous vaporization is to use
a nuclear reactor and/or another rocket using conventional fuels. I
believe that either of these two ideas will work.

An added bonuis of the 'Steam Rocket' is that at high temperatures --
1000 deg. C. to 2500 deg. C. -- the water molecule splits. When this
molecule comes back together, which it will as soon as the temperature
drops, it generates enormous explosive force and roughly 6000 deg. F.
temperatures. Basically, at this point, you have a hydrogen-lox
combustion with the ISP of the hydrogen/lox engine like the SSME (Space
Shuttle Main Engine) for example.

Even if a small amount of the water vapor 'cracks' and then comes back
together as a hydrogen lox reaction it would add enormous explosive
reaction to the Steam Rocket and should make it a practical rocket for
use in Outer Space.


tomcat

Danny Dot wrote:

Interesting idea. Water on a nuclear core would certainly make a good
rocket.

Oh ... grow up.

http://www.neofuel.com

When I first became an astronaut instructor in 1990,

That explains it then, astronaut training at NASA sure has taken a ****.

Now we get the likes of Joe Acaba for astronauts.

And people wonder why NASA is failing.

http://cosmic.lifeform.org

"Danny Dot" wrote in
:

to "handle", and is expensive. Maybe water dumped on a nuclear
reactor has its place in the world. It could probably get to SSME
like ISPs because in both cases the exhaust gases are both water. The
question is -- can a nuclear core go to the same temperature of the
combusion chamber of an SSME.

And there's the problem; a practical nuclear thermal rocket can't
get anywhere near the temperature of a typical chemical rocket, and
has to provide hundred of megawatts to gigawatts of thermal energy
in a very compact and relatively lightweight package. I think the
SSME propellant temperatures in the combustion chamber are up around
6000F; a nuclear thermal rocket tops out near 1500F--at present levels
of technology. The sole advantage of a water rocket is the reaction
mass density, and most chemical rockets easily beat its performance.

tomcat doesn't have a clue.

--Damon

In article ,
Danny Dot wrote:
ISP is only a function of the velocity of the gases as they escape the
nozzle. Higher temperatures lead to higher velocities, as does lower
molecular weight of the exhaust gas. This is why a LOX/H2 rocket has a
higher ISP than a kerosene/LOX -- water is a lighter molecule than the
combustion products of kerosene/LOX.

Actually, the real story there is more complex and somewhat different --
even though many textbooks claim the above -- because temperature and
molecular weight are not independent in a chemical rocket. (John Clark's
"Ignition!" is one of the few references that gets the story right,
probably because Clark was a propellant chemist rather than a rocket
engineer, and had to understand the underlying details.) The correlation
between lighter molecules and higher velocity is due to indirect effects.

For a nuclear rocket, though, the situation is much simpler, because there
temperature *is* independent of propellant. There, molecular weight
matters directly and strongly.

When I first became an astronaut instructor in 1990, I was shocked to find
out the orbit engines on the shuttle (and most other orbit vehicles) do not
use pumps... This keyed my research into
ISP and I discovered a small chamber pressure does NOT mean low ISP.

Correct. To a first approximation, Isp is independent of pressure.
Higher chamber pressure pushes more gas through per second, but it's the
thermal energy of combustion that determines Isp, and that's not (very)
dependent on pressure. The RL10 has slightly higher Isp than the SSME
despite a much lower chamber pressure.

Where it really gets counterintuitive is with cold-gas thrusters on
spacecraft. The gas is typically stored at very high pressure... but it
goes through a pressure reducer/regulator before reaching the thrusters!
This boggles novices' minds. The reduction doesn't matter, because it's
the thermal energy of the gas that drives the expansion through the
nozzle, *not* the feed pressure.

I also
discovered that ISP in the shuttle computer software is "defined" as VEX,
which is the exhaust velocity of the SSMEs. The Russians talk exhaust
velocity a lot and use the term ISP less than we do.

The Europeans confuse the matter further by using velocity units (rather,
a mixed-up version of velocity units -- N-s/kg) and calling it Isp. It's
exhaust velocity that really matters, but Isp is more convenient for
comparisons, not least because it extends gracefully to airbreathing
engines, where exhaust velocity does not tell the full story. Isp is a
better choice as a figure of merit, even though it needs to be converted
to turn it into something physically meaningful.

BUT, having said this, H2 takes HUGE volume to store, can't be stored on
orbit, requires major engineering to "handle", requires expensive components
to "handle", and is expensive. Maybe water dumped on a nuclear reactor has
its place in the world.

A better choice is ammonia -- almost as easy to store as water, comes
apart easily and completely into nitrogen and hydrogen when you get it
hot, and *doesn't* recombine. The resulting average molecular weight is
about 8.5, giving a nuclear-rocket Isp about half that of hydrogen. Water
doesn't break down significantly at any reasonable reactor temperature, so
its molecular weight stays at 18, giving about 1/3 of the hydrogen Isp.
(Worse, it's an oxidizing agent when you get it hot, which is hard on the
usual reactor materials.)

It could probably get to SSME like ISPs because in
both cases the exhaust gases are both water. The question is -- can a
nuclear core go to the same temperature of the combusion chamber of an SSME.

No, not even close. The core of an orthodox solid-core nuclear rocket is
limited, by materials issues, to considerably lower temperatures than that
of a high-pressure oxygen/hydrogen flame. (The nuclear core has to run
hotter than the gas, whereas the chamber walls of a chemical rocket can
run much cooler.)
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