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kilowatt
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High Energy Laminated Rocket Propellants
Please keep in mind this is not meant to be a practical thing for rockets that are supposed to be utilitarian, reliable, or storable. I simply find
the idea of pushing propellant chemistry to the limits to get the highest possible specific impulse is fascinating. That is what this is about, at
least in the solid fuel department. I am also interested in liquid and hybrid propellants. This mainly applies to smaller highly experimental
engines, some even quite small, as high cost or difficulty of synthesis limits the quantities of a lot of this stuff. The construction method I will
describe is tedious and some of the propellants are very hazardous materials that demand the utmost respect during synthesis and handling. I'm sure
some of these rockets are likely to fail catastrophically. Nonetheless it is an interesting area which not many people have delved into.
I have considered the possibility of some very energetic and reactive solid fuels and oxidizers for rocket engines. Examples of some of these fuels
are lithium hydride and other light metal hydrides or borohydrides or light metals themselves such as lithium, sodium, or beryllium, or other things
like cubane (actually quite safe/stable), decaborane or mixtures thereof, or mixtures containing hydroxylamine. Some of the possible oxidizers are
N2O5 (very volatile) or other nitronium salts, perfluorate or fluorate salts, mixtures containing hydroxylammonium salts, or alkali metal peroxides
and superoxides. I have been considering combinations of many of these with each other or with other less exotic propellants.
Clearly many of these propellants are so sensitive and reactive that they could not even come in contact with each other, much less be mixed into a
composite propellant. They would simply explode, many as soon as they came into contact. Some of them are quite volatile, subliming solids, and some
of them are very pyrophoric and cannot even be handled outside of an inert atmosphere. As a method to allow them to be used anyway, I have proposed
laminate propellants.
For core burning or ring burning designs the fuel or oxidizer constituents would be individually cast or grown into solid plates of appropriate
thickness with strochiometric mass and a hole in the center for the burn chamber. They could be combined with a suitable fibrous material such as
fiberglass or steel wool (where compatible) for strength, or cast or grown as a single crystal plate. The plates of fuel and oxidizer material would
then be stacked alternately in the rocket tube throughout its length and glued or mounted in with a thin dividing layer between each. A protective
lining would then be applied to the inside of the burn chamber, and a line or layer of flash powder or similar would be applied down its length,
bridging all the plates. This would be connected to an electric ignition, and the burn chamber would be sealed with argon gas inside by a cover film
over the nozzle. Some of the more volatile propellants would require that the rocket be kept refrigerated until ignition.
The basic equipment needed for building such rockets would include an isolation glove box, possibly refrigerated, casting trays, and most importantly
thorough knowledge of the properties and compatibilities of each of the propellant constituents, as well as testing with small samples.
A thickness for the plates would have to be chosen, probably through experimentation, so that the burn rate would be controlled, and yet the burn is
even and complete. There could be issues regarding differing melting points of thermal conductivity of the different constituents, and there may be
other unexpected issues with the burn rates of the plates.
Suggestions? Criticism? Comments? All welcome.
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halogen
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No such thing as fluorates or perfluorates AFAIK. The rest of it seems like a bad idea too; you're just making complicated pipe-bombs.
F. de Lalande and M. Prud'homme showed that a mixture of boric oxide and sodium chloride is decomposed in a stream of dry air or oxygen at a red heat
with the evolution of chlorine.
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vulture
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| Quote: |
A protective lining would then be applied to the inside of the burn chamber, and a line or layer of flash powder or similar would be applied down its
length, bridging all the plates. |
You're crazy. Flash powder in a rocket just turns a rocket into a giant uncontrollable fire cracker.
You want thrust, you need a gradual push. Not mass which turns into gas in two microseconds.
Try building a KClO3/sugar rocket first and see how hard it is to prevent that from simply exploding.
[Edited on 28-10-2007 by vulture]
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kilowatt
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I have seen perfluorates mentioned in various internet sources, albeit scarsely. I guess now that I think about it, it would be odd for fluorine to
be in that oxidation state, though. Perhaps those ions are not possible; they are the only candidates I have looked that there is not extensive
information on.
Regardless, you seem to have a very pessimistic view on experimental rocketry, halogen. I am interested in whether this propellant arrangement can
function to yield high performance. The idea is to come up with something that will not explode, while developing a higher specific impulse than
other solid propellants. As I mentioned first thing in my post, I am not trying to come up with a revolutionary new propellant for launch vehicles or
anything, since it would be too expensive and dangerous, not to mention I'm just a regular guy without any credentials. I should not actually have to
repeat myself there. I am simply bored with the standard solid propellants used in amateur rockets and am looking to find higher impulse onces, for
the heck of it, for science. It doesn't have to be viable for space transport, or commercial rockets, or anything else any more that any other
amateur rocket does. I assure you these engines will be no more feckless than a typical Estes engine, and FAR less feckless than a typical pipe bomb.
These at least have experimental value.
| Quote: |
Try building a KClO3/sugar rocket first and see how hard it is to prevent that from simply exploding. |
I have only worked with powdered metal based propellants before, but they aren't too hard to keep from exploding. I can only assume KClO3/sugar is
even easier. Burn rates and chamber pressures can readily be calculated anyway with the most common propellant compositions. I had a little more
trouble with Mg/KMnO4 based propellant; I had one engine work well but didn't have a way to measure the thrust, then I had one burn too slowly to
register a thrust on my pulley system, then another explode after about one second (it was an end-burner, too  ). I think I just didn't have enough binder in that one and it developed cracks. I successfully fired an aerospike
ring burning engine with Mg/KNO3, but had far too much oxidizer as the epoxy binder didn't work out quite stochiometrically as I expected it too.
That one was just buried in a hillside for firing the first firing, but that engine is reuseable. I need to rig up a sensor to record thrust
dynamically.
[Edited on 28-10-2007 by kilowatt]
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vulture
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Yes, but anything you propose is either more hazardous (using alkali metals for example) or technically more complicated (compartimentation of
oxidizer/fuel) than which is used in advanced space rockets.
There's a limit to maximum rocket fuel performance where you simply cross into explosion.
If you want a crazy idea, here's one I just came up with:
Try dissolving KMnO4 and naphtalene in acetone and allow it to evaporate. Burn and watch. Warning: likely very hazardous.
| Quote: |
I can only assume KClO3/sugar is even easier. Burn rates and chamber pressures can readily be calculated anyway with the most common propellant
compositions. I had a little more trouble with Mg/KMnO4 based propellant; I had one engine work well but didn't have a way to measure the thrust, then
I had one burn too slowly to register a thrust on my pulley system, then another explode after about one second (it was an end-burner, too ). |
You're kidding right? My Mg/KMnO4 explodes in quantities of more than half a gram when unconfined! Either way your Mg is of lousy
quality or you're not mixing it properly. Same goes for KClO3/sugar. Dry and intimately mixed KClO3/sugar with some Fe2O3 will blow
up when using the slightest confinement. Trust me, I've tried.
[Edited on 28-10-2007 by vulture]
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kilowatt
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What are you getting at? KMnO4 can never make a decent rocket propellant anyway
as its byproducts are too heavy. Nonetheless I have experimented with it. KMnO4/glycerine is fun enough if you just want something to burn.
| Quote: |
Either way your Mg is of lousy quality or you're not mixing it properly. |
It was perfectly good magnesium, but very not-finely-divided. It was packed tight, but had large grain size. Of course high performance was not
reached because the grains were too big to burn completely in the chamber. You can see that by the disproportionately bright exhaust. http://www.chrisf.4hv.org/projects/rockets/test1.avi My laminated propellant proposal simply takes large grains like that to the next level,
while making sure they remain in the chamber.
[Edited on 28-10-2007 by kilowatt]
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vulture
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| Quote: |
My laminated propellant proposal simply takes large grains like that to the next level, while making sure they remain in the chamber.
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So you're making a heterogenous propellant with large grain size...which benefit do you expect from that?
Say you'd use an alkali metal and actually manage to ignite the "propellant". The blocks would simply melt and sink out the nozzle where they'd burn
atmospherically once outside the rocket. That's just one of the many problems with the design.
Why not try it by filling a rocket chamber with naphtalene mothballs and filling up the holes with oxidizer? That's pretty much the approach you're
after it seems.
[Edited on 28-10-2007 by vulture]
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kilowatt
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With something like an alkali metal, a fibrous binder would be needed to keep it from running out at once. It could still be a problem though. For
that reason the alkali metal hydrides would look more promising. There could be similar issues with any of the lower melting or subliming chemicals.
If the fuel and oxidizers could conduct heat or vaporize at a remotely similar rate though, I don't see why it couldn't work. I have considered
strongly chilling the rocket before ignition, as long as the burn is brief enough.
| Quote: |
Why not try it by filling a rocket chamber with naphtalene mothballs and filling up the holes with oxidizer? That's pretty much the approach you're
after it seems. |
That sort of less organized approach would be more suitable to an end burning design, but end burners subject the chamber walls to the full combustion
temperature, which will cause it to melt. For a core burning design something more structured would be nice. Not to mention that cramming some of
these highly reactive oxidizers in with a fuel in that manner would be incredibly dangerous/suicidal.
I forgot to mention, the aerospike I mentioned earlier, which also contained a fairly large grain, did not seem to eject any unburned fuel like the
earlier Mg/KMnO4 burn. It's only problems were lots of unburned oxidizer, as I got the stochiometry way off, and as such it burned very smokey and
too slowly. The burn wasn't very consistent either, because the ring burning design was very hard to pack well (a laminate propellant would solve
that, though). Otherwise, fairly decent I guess. I used plenty of binder. http://www.chrisf.4hv.org/projects/rockets/aerospike_1/aero1...
My hope is that with a laminate propellant the grains would also say somewhat well bound. The fuel/oxidizer plates could potentially be made up of
bound mixtures as well, giving a higher melting point and lower thermal conductivity. I've considered other arrangements too such as thin coaxial
laminates, or pie-shaped divisions that run the whole length (but I think the latter would be a really bad choice for many obvious reasons). The
plate laminates seemed the most feasible. They are looking less feasible depending on their thickness, though. I should think thin plates with less
tendency to run out or erode unevenly would be best, with an equally increased level of tedium in assembly.
[Edited on 28-10-2007 by kilowatt]
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hinz
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Learn some basics of rocketry first, if your Mg/KMnO4 propellant won't explode, you would melt your rocket case down at the temperatures Mg burns, and
the MgO produced will stay inside your molten case or sinter on the parts of the nozzle, where the pressure is decreased (the bell shaped end). The
nozzle would be tortured by liquid Mn and the trust wouldn't be good as most of the producs of the reaction (MgO) won't leave the nozzle, only the K2O
and the liquid Mn would leave it and generate trust.
There is a reason why Werner von Braun has invented the liquid propellant rockets, because those designs you make won't work as no material will hold
up the temperatures involved without beeing cooled.
With liquid propellants you can cool the nozzle with propellant and cheaper and easy handable propellants like kerosene/LOX can be choosen without
decrease in reaction enthalphy and thus trust.
If you want to mess around with metall hydrides (your last crazy idea), fist look at their properties you you don't blow yourself up in a clowd of
hydrogen (because your propellant got sligtly wet) as you ignite the fuze. (supposed you even get some metall hydrides)
If you still wan't to play with rockets, start with low tech KNO3/sugar,
here are some good pages for you:
http://www.jamesyawn.com/index.htm
http://www.nakka-rocketry.net/index.html (look at the rocket theory)
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kilowatt
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I discounted KMnO4 as a rocket oxidizer long ago, due mainly to its high exhaust mass and poor burn characteristics, and due to my past experiments
which I mentioned. I have also discounted end burning designs. No new info here. Also note that in a core burning design the case does not see the
combustion temperatures until burnout, and that even the flame temperature of the most mundane propellants exceeds the melting point of most if not
all materials. That is why we use ablative nozzles like graphite or clay, and why real solid rockets like the Shuttle SRB, Patriot missiles, and
large amateur rockets all use a core burning design, usually shaped so that the burn area remains constant.
I am familiar with liquid rockets, their advantages, as well as their complexities. I am just as interested in them as solid ones. I intend to build
one someday using a pressure fed pump http://www.flometrics.com/rockets/rocket_pump/pump-animation... and a regeneratively cooled aerospike nozzle. I don't really have the time now
but it's already on my to-do list. My main draw toward the aerospike nozzle is that it is easier to construct with a graphite spike without access to
fancy lathes and machine tools, even though it is more difficult to obtain a proper expansion ratio especially for a static test. I also have a
larger solid fueled aerospike in the works, which will use Al/NH4NO3 composite propellant. I want to become more familiar with their design as not
only are they easy to put together, but they compensate to some degree for change in ambient pressure as they climb.
I am familiar with the properties of alkali metal hydrides and borohydrides as well as their synthesis, and I'm not sure why you assume I would not be
before considering their use.
I am already familiar with Nakka's page. http://www.nakka-rocketry.net/index.html
I simply wish to experiment with alternative solid fuels. I am not simply some uninformed newbie whose first instinct is to come up with rash ideas.
You have all brought up interesting points, but there is nothing in basic rocket theory that says a laminated propellant design or high energy
propellants is outlandish. It is not too different from the equally exotic liquid propellants tested in the 1950s by the US government, the main
difference being that you can easily control the flow rate in a liquid rocket, while in a solid rocket you have to make use of burn geometry and the
like.
[Edited on 28-10-2007 by kilowatt]
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Eclectic
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Your experiments with making lithium metal and some of the other experiments in your project pages would likely help establish credentials...
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Twospoons
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Chemical considerations aside, a better way to isolate hypergolic propellant components might be to pelletise the lower volume component, coat it
with a compatible isolation barrier, then mix the pellets with the other component in the grain. Sort of like flammable concrete. I would imagine
such a composite structure would be stronger than laminating, with better control of burn characteristics, less risk of fracture (with resulting
catastrophic burn surface increase). It would also be a damn sight easier to build.
Helicopter: "helico" -> spiral, "pter" -> with wings
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franklyn
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A propellant used for rocket propulsion is inherently very much less efficient
thermodynamically than the same amount of that propellant used inside of a
gun barrel , where explosive deflagration couples nicely with the constrained
expansion of the gas produced. The rate of acceleration of a missile is
determined of course by the pressure acting on it from the gas produced.
The pressure produced is directly the result of the quantity of gas and to a
lessor extent the temperature. Optimally for a rocket , this thrust is designed
to just marginally exceed the takeoff weight by a small percentage , and
ideally the rate of burn progressively becomes less as does the weight. For
the best efficient use of the available energy it must be burned slowly. The
duration this is sustainable is determined by the rate which the propellant is
consumed not how energetic it is , which only affects the dimensions of the
vehicle size for a fixed payload. Better to have a large cheap rocket than a
small expensive one.
Remember that the Saturn 5 that boosted the moon explorers into orbit was
fueled by liquid oxygen and keroene , not all that sexy. Solid motors are just
as bland , a mix of resinous fuel binding the oxidizer. The most energetic
propellant schemes are used solely by military missiles for reduced size and
portability. The legendary Titan II was fueled with IRFNA ( Inhibited Red
Fuming Nitric Acid ) and UDMH ( Unsymetrical Dimethyl Hydrazine ) a hypergol
which self igniting when blended. A reason this surpassed the performance of
cryogenic fuel schemes is that the cold fuels have that much less latent heat
than a fuel at ambient temperature and this must be made up from the energy
provided by burning. In effect cold fuels are handicapped , one reason less
enegetic solid fuels compare favorablty. There are further considerations as to
the layout of a vehicle. The X-15 rocket plane was fueld with liquid oxygen and
ammonia because these are consumed at rates which maintain the same level
trim and center of mass distribution within the plane. Interestingly there is more
hydrogen in a gallon of gasoline than there is in a gallon of liquid hydrogen ,
due to the relative densities , so the tank can be smaller and therefore lighter
and does not additionally require refrigeration. Current research for more
energetic fuels looks to strained ring hydrocarbon fuels such as cyclopropane
and unsaturated alkenes or even alkynes and boranes. Energetic oxidizers tend
to be explosive posing a safety threat. Solid nitryl perchlorate can be made from
NO2, ClO2, and O3 gases: 2 NO2 + 2 ClO2 + 2 O3 => 2 NO2ClO4 + O2
.
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APCP
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| Quote: | Originally posted by kilowatt
I also have a larger solid fueled aerospike in the works, which will use Al/NH4NO3 composite propellant.
[Edited on 28-10-2007 by kilowatt] |
ANCP chuffs when using Al. Unless you can get some cenes, you'll want to use Mg instead of Al.
Be would be your best bet for high performance metal.
You start reaching the upper limits of solids Isp when you use HNF/GAP. Expensive as hell, hard to get, hard to make....
Still, good luck on any experimentation. Get some diagrams for your aerospike designs made up, I am intrigued. My team plans on using an aerospike on
an R motor for a space shot. Probably won't because they are pain, but one varient of the motor has an aerospike.
Under the spreading chestnut tree, I sold you and you sold me. There lies they and here lies we, under the spreading chestnut tree.
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Eclectic
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Has anyone tested LiBH4 as a high energy fuel additive?
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kilowatt
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| Quote: |
Chemical considerations aside, a better way to isolate hypergolic propellant components might be to pelletise the lower volume component, coat it with
a compatible isolation barrier, then mix the pellets with the other component in the grain. Sort of like flammable concrete. I would imagine such a
composite structure would be stronger than laminating, with better control of burn characteristics, less risk of fracture (with resulting catastrophic
burn surface increase). It would also be a damn sight easier to build. |
Interesting. I would be extremely worried about what would happen if that isolation barrier were to mechanically break down during loading though. I
wouldn't want to be anywhere near it. Until I have a safe way to work with it in that way, it's just too risky. Just one little scratch you know...
| Quote: |
Your experiments with making lithium metal and some of the other experiments in your project pages would likely help establish credentials...
|
Not really, so far my every attempt at alkali metals has failed. Of course not many
people have done better (congrats to those who have), but that is no excuse. I have my fingers crossed for my new mini cell which I have finally
decided to first fire up with eutectic LiCl/KCl. My most successful chemistry projects so far are my distillation rig and my scrap lead refining
process (which I have yet to implement at large scale). Most of my most successful projects have been electrical, such as my reconnection guns.
| Quote: |
ANCP chuffs when using Al. Unless you can get some cenes, you'll want to use Mg instead of Al.
Be would be your best bet for high performance metal. |
Interesting note. Mg is no problem, I have quite a bit, it's just more expensive than Al. I made an atomizer for magnesium that uses molten
magnesium in a steel bottle, pressurized with argon to force it through an orifice which is electrically charged so the droplets repel each other. I
have not operated it yet, but it will spray the metal droplets into an argon purged trap filled with xylene, which will have an oppositely charged
plate at the bottom. Beryllium would be nice, but it's incredibly expensive, not to mention the exhaust would be highly toxic, as well as the fuel
itself during handling. On top of that it's very high melting and difficult to work. Still, I have considered its use for some very very small upper
stage engines, since you can buy Be powder by the gram cheaper than you can buy any other form of the metal.
| Quote: |
Get some diagrams for your aerospike designs made up, I am intrigued. |
I've already got them. Check http://www.chrisf.4hv.org/projects/rockets/aerospike_mkII/
The case and end cap are made of regular 6061 aluminum with a good burst pressure safety margin even at elevated temperature, and I would like to use
titanium for the central core, which will be cooled in flight by air flowing through the entire length of the tube from a hole in the nose cone and
coming out the end of the spike, simulating an infinite spike length. Obviously the case temperature must not be allowed to exceed 300°C or so where
the strength reduction is just over 50%. I plan to re-temper it to T-6 after each firing. Some finite element analysis would be wonderful to aid in
shaping the spike appropriately, perhaps you know a bit about that?
Here's the small Mg/KNO3 aerospike I tested before, as well as the crudded up results from the far-too-lean propellant composition. This rocket was
designed and built as a static test engine and not the slightest effort was made to use lightweight materials which would be flyable.
http://www.chrisf.4hv.org/projects/rockets/HPIM1251.JPG
http://www.chrisf.4hv.org/projects/rockets/aerospike_1/
And here is a cutaway my proposed liquid aerospike design.
http://www.chrisf.4hv.org/concepts/mini_aerospike.jpg
http://www.chrisf.4hv.org/concepts/aerospike_rocket.jpg
You can ignore the teflon piston pumps though as I have since discovered the much simpler, lighter, and more elegant pressure fed pump design that I
linked before.
| Quote: |
Has anyone tested LiBH4 as a high energy fuel additive? |
I would certainly like too, give its higher energy and hydrogen content. Are you talking about solid borohydride (thats definitely an area for my
laminate propellant thing, being one of the fuels I proposed for it) or a liquid fuel that contains it in solution? THF is a good solvent for it, as
well as a rather strained compound.
[Edited on 28-10-2007 by kilowatt]
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froot
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The risk of failure of the divisions between the various components of the propellant cake and the potential consequences simply outweigh the
benefits. Some of those additives you proposed are rather scary in a confined tube, nevermind together with reactive oxidisers in the same tube.
In your particular design, have you considered arranging the divisions vertically? This would obviously mean that it would burn progressively up the
chamber. I can appreciate the innovative approach, but please test your concepts with mild fuel components first. If something goes wrong, we'd like
you to report your findings to us and you'll need at least one finger to type it in
I would say that the next step forward with rocketry would be re-useable motors with variable nozzles that can be throttled, extinguished, and
re-ignited using fuels generating 'eco-friendly' exhaust gases.
We salute the improvement of the human genome by honoring those who remove themselves from it.
Of necessity, this honor is generally bestowed posthumously. - www.darwinawards.com |
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vulture
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You know, using metal hydrides isn't THAT crazy, just don't use them in combination with oxidizers. Just using them as a controllable source of H2
which is then burned eliminates the need for pressurized H2 gas.
The only problem is where to get the oxygen from.
Also, if you have acces to perchlorates, you might want to try and make lithiumperchlorate. It's a good oxidizer with a VERY high oxygen content. Just
awfully hygroscopic IIRC.
[Edited on 29-10-2007 by vulture]
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Eclectic
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There is a report on Dann's site that lithium perchlorate is completely soluble in epoxy. There is some question as to whether the resulting fuel
would be prone to high order detonation.
I was thinking of solid LiBH4 powder as a replacement for aluminum in a solid propellant grain.
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kilowatt
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Lithium perchlorate might be a good one, would definitely have to be sealed though. I've made lithium nitrate before, it too is extremely
hygroscopic. I'm pretty sure that sample is sitting around in my room somewhere in aqueous solution which it picked up from the air. Good oxidizer
when dry though. 
| Quote: |
I was thinking of solid LiBH4 powder as a replacement for aluminum in a solid propellant grain. |
Holy shit. I'm thinking that would tend to explode...
| Quote: |
The only problem is where to get the oxygen from. |
Hybrid propellant, with borohydride decomposition happening in a separate chamber connected to the burn chamber via injectors, most likely.
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Antwain
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Just a caution- even though you don't have Be. I know (or knew, he died but maybe not because of this) a guy who had made himself sick from chronic Be
exposure. He used to repair antique watches, and had to file down Be springs. He had a kind of permanent pneumonia and was always coughing. Apparently
it can give you cancer too and possibly screws with your bones if it is absorbed (which the metal probably can't be).
Hey, if you were feeling particularly suicidal you could arrange a hypergolic fuel based on 100% H2O2 and LiH. low exhaust weights 
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kilowatt
Hazard to Others
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Registered: 11-10-2007
Location: Montana
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Yeah, that sounds like beryllium poisoning , I don't think you have to inhale much
(doesn't matter what form, metal, oxide, etc) to get chronic symptoms. Childsplay compared to boranes though, specifically pentaborane (liquid) or
pentaborane (solid). That shit is evil, I would definitely not want to be exposed. They are high impulse though. There is a roundabout chemical synthesis for pentaborane but as far as I know
decaborane would have to be made with hydrolysis of either diborane or pentaborane, giving low yields. I think that's a ways off for me.
The highest impulse chemical rocket propellant known and tested is F2 + Li/H2 liquid tripropellant. Isp was 542, meaning it obviously didn't blow up.
They even considered using FLOX, a mixture of F2 and O2 on the Saturn V, but obviously decided against it because of corrosion, cost, and the
logistics of pumping out huge amounts of HF into the air.
[Edited on 29-10-2007 by kilowatt]
The mind cannot decide the truth; it can only find the truth.
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franklyn
International Hazard
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Registered: 30-5-2006
Location: Da Big Apple
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The most energetic binary components which come to mind would be
LiH + HF -> LiF + H2 , variations of this comprised of solids would be
NH4F + NaNH2 -> NaF + N2 + 3H2
2 : 5 , molar expansion
and I've posted this before elswhere , Bifluoride and Hypochlorite
2 NH4F.HF + 2 Ca(ClO)2 -> 2 CaF2 + 4 H2O + 2 HCl + N2
4 : 9 , molar expansion
Hydrazine Fluoride and Chlorite
2 H2NNH2.HF + 2 Mg(ClO2)2 -> MgF2 + 4 H2O + 2HCl + 2N2
4 : 9 , molar expansion
Somewhat more exotic is Methyl Hydrazine Fluoride salt
CH3HNNH2.HF + KClO4 -> KF + CO + 3 H2O + HCl + N2
2 : 7 , molar expansion
Then there is borane compounding
2 NH4F.HF + NaBH4 -> NaF + BF3 + N2 + 7H2
3 : 10 , molar expansion 70 % Hydrogen by volume , 9.2% by weight
4 H2NNH2.BH3 + 6 NH4F.HF -> 4 BF3 + 7N2 + 29H2
10 : 40 , molar expansion 72.5 % Hydrogen by volume , 11 % by weight
These materials are more readily available
2 CaH2 + 2 NH4F.HF -> 2 CaF2 + N2 + 6 H2
4 : 9 , molar expansion 67 % Hydrogen by volume , 10.2 % by weight
CaH2 cannisters - density 1.70 gm/cm³ , melts at 675º C
http://www.fairradio.com/catalog.php?mode=search&query=M...
NH4F.HF - density 1.51 gm/cm³ , melts at 124º C with decomposition
generally available 96% technical grade
http://store.hvchemical.com/browse.cfm/4,1061.htm
http://www.gfschemicals.com/chemicals/gfschem-1134.asp
http://www.baddley.com/S/FL165.htm
Call for quote
http://www.fluoridearc.com/pages/fluoridesac.html
http://www.kyantec.com/catalog.htm
_______________________________
A way to enhance thrust with hydrogen exhaust is to use an augmentor
a device which acts somewhat like an aspirator. This may even work better
with the aerospike nozzle.
See - http://www.aardvark.co.nz/pjet/augmentors.shtml
http://gltrs.grc.nasa.gov/reports/2006/TM-2006-214224.pdf
.
[Edited on 31-10-2007 by franklyn]
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kilowatt
Hazard to Others
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Registered: 11-10-2007
Location: Montana
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The air breathing augmenter is neat. With an aerospike nozzle, I can see the augmenter burning the hydrogen rich exhaust in air up to a certain
altitude, where the augmenter could be ejected and the mode of operation would then become a non-airbreathing rocket.
Calcium is a little heavy; lithium hydride would be much preferred to calcium hydride, and lithium borohydride has an even greater hydrogen content.
I am surprised that ammonium bifluoride is available for purchase so easily, interesting links.
The mind cannot decide the truth; it can only find the truth.
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Eclectic
National Hazard
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Registered: 14-11-2004
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Pentaborane Rocket Fuel: Safe handling and storage
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