HYDRAL - frozen aluminium hydrazine rocket system

Sounds like a suicide tought
Do you have anhydrous hydrazine?
Hydrazine hydrate is alkaline enough to react with Al.
Also,some oxidiser would be great to burn the H2 that is generated.

Quote: Originally posted by ecos

I am sorry to deviate the topic a little bit from its target but I would like to know how would you reach nano Al powder? is it possible to reach 80-5 nm using homemade ball mill ? but how much would it take to mill till this size? I checked the ALICE propellent, I think using water is not the best option, the better reaction would be : 3ZnSO4.7H2O(s)+22Al(s)→11Al2O3(s)+3Zn(s)+3S(s)+21H2(g)ΔH=−9,199 kJ This is stated in : Method for Manufacturing Energetic Material Composites US 20120216926 A1 [Edited on 6-11-2015 by ecos]

Hi DeltaH,

This is not my equation , I got it from this patent : Link

I think you are right regarding ZnS , I think this is also a propellent with Isp=50 .

H2O2 would be a better oxidizer but it has high cost and safety precautions is needed. (I am not sure about stability)

Hydrazine would be superior but the same probls : higher cost and very toxic.

Thats why I like the idea of the patent regarding hydrated compounds. There exist a table inside the patent for different compounds.

do you plan to make any experiments or just logical thinking ?





[Edited on 6-11-2015 by ecos]

Hi ecos,

Thanks for that, yes the hydrates are an interesting twist. I will think on it some more. Never realised Na2S had so many crystal waters

For now, HYDRAL is out of my reach for testing, but hydrates are more amateur friendly, so only a thought experiment for the time being and for others if they're interested in it.

The HYDRAL notion has a far more exotic parent: https://www.sciencemadness.org/whisper/viewthread.php?tid=56...

That being a DARPA-style idea for a super gun (light gas cannon) propellant. You gotta love that Isp of 1300/s Funny nobody said that it's impossible?



[Edited on 7-11-2015 by deltaH]

I hope to see your results for your experiments on hydrates . I am still investigating how to reach nano Al. it would take more than 1 month in a ball mill to reach 5 nano

for DARPA-style idea , I think it would make super gun for sure

I wonder how I would build such mill. It seems very complex !

Building is not that simple. My school dont even has one (Chemical enginier)
Has a good price too. Imagine the black powder made there

Okay, I did some back-of-the-envelope thermodynamics.

I couldn't find any standard heats of formation for aluminium cyanamide, so I modified the equation by adding more aluminium and assuming this would react with aluminium cyanamide to form aluminium carbide and more aluminium nitride, so that I can use known values of standard heats for aluminium carbide and nitride:

6(NH2)CO(s) + 18Al(s) =>Al4C3(s) + Al2O3(s) + 12AlN(s) + 3CO(g) + 12H2(g)

The specific enthalpy of reaction is a paltry -4.7kJ/g for such a fuel

Specific gas volume is also only a paltry 397sccm/g fuel mix.

So performance would be shitty, but then it's so easy to make, possibly very safe and cheap, so I don't know...

[Edited on 8-11-2015 by deltaH]

Some more thermodynamics, I thought I might compare the heats with another low melting fuel, like xylitol. The equation considered:

3C5H12O5 + 30Al => 5Al4C3(s) + 5Al2O3(s) + 18H2(g)

I was surprised to find that xylitol performs slightly worse than urea theoretically:

Specific standard heat of reaction: -4.6 kJ/g reagents
Specific gas volume: 318sccm/g reagents

I suppose this is because the xylitol is acting as an oxidant in this case and xylitol is a better fuel (reductant) than urea, so a worse oxidant.

But it's nevertheless still surprising to see that you might launch a candy rocket that contains no oxidant at all

Xylitol melts at 92C, so a xylitol-aluminium powder mix should also be readily castable.

[Edited on 8-11-2015 by deltaH]

Quote: Originally posted by kecskesajt

Building is not that simple. My school dont even has one (Chemical enginier) Has a good price too. Imagine the black powder made there

I read some documents about this machine.
I can build similar one that can do the same functionality but I miss some parameters here.
I don't know what should be the optimum speeds for the both moving parts. I also miss the size of the jar ,the circular moving disk,..... !.

If i have all parameters I think I can build similar one.

Quote: Originally posted by deltaH

Some more thermodynamics, I thought I might compare the heats with another low melting fuel, like xylitol. The equation considered: 3C5H12O5 + 30Al => 5Al4C3(s) + 5Al2O3(s) + 18H2(g) I was surprised to find that xylitol performs slightly worse than urea theoretically: Specific standard heat of reaction: -4.6 kJ/g reagents Specific gas volume: 318sccm/g reagents I suppose this is because the xylitol is acting as an oxidant in this case and xylitol is a better fuel (reductant) than urea, so a worse oxidant. But it's nevertheless still surprising to see that you might launch a candy rocket that contains no oxidant at all Xylitol melts at 92C, so a xylitol-aluminium powder mix should also be readily castable. [Edited on 8-11-2015 by deltaH]

How much aluminium powder do you guys need for a planetary size ball mill?! Seriously though, never heard of them before, guessing it creates way more friction than a tumbler.

Regarding the urea/sorbitol + nano aluminium powder propellants, is there a burn rate or pressure exponent known for similar kind of propellants? I'm guessing slow burnrates (if any at atmospheric pressure) and very small pressure exponent, meaning you would have to run ridiculously high chamber pressures with something that burns exceedingly hot, without much gas production. Im picturing a thermite rocket or similar.

An epoxy style amateur friendly propellant using AN would be a good use of the nano Al IMO, maybe hard to get reliable as avg. particle size and oxide content can be different between batches.

[Edited on 8-11-2015 by nitro-genes]

planetary ball mill is classified as high energy mill. It depends on the centrifugal force rather than the gravity as other in ball mills.
if the rotation speed is high the media would have enough energy to strike the Aluminium with more power. This is nice idea which would save much but but the probability of hazards would increase since the sparks might exist.
it would take time to make a similar one. I found many patents for designs on google.

AN+Al+epoxy is not that good propellent, it has a lot of challenges. you will find experiments here : http://www.nakka-rocketry.net/anexp.html
AN tend to cake and is very hygroscopic ....blah blah.

I think any compound that has hydrate + Al might be a very good propellent. I think if urea hydrate exists it would be better than urea alone

It was nakka's experiments indeed that I had in mind, I was thinking that the disadvantages of normal aluminium powder in these types of propellants may be overcome by the use of nano aluminium, but perhaps not.

Other idea might be urea-peroxide adduct for use in propellant, don't know if it has been mentioned before and possible compatibility issues with aluminium powder (wouldn't directly think so), it is rather easy to make though. May need some down-tuning to prevent explosion instead of burning though.

https://en.wikipedia.org/wiki/Hydrogen_peroxide_-_urea

[Edited on 10-11-2015 by nitro-genes]

Carbamate peroxide (urea hydrogen peroxide) might be a fantastic idea... if it won't explode or spontaneously ignite, but it might well not. Pity you won't be able to melt cast it though

[Edited on 10-11-2015 by deltaH]

Quote: Originally posted by nitro-genes

It was nakka's experiments indeed that I had in mind, I was thinking that the disadvantages of normal aluminium powder in these types of propellants may be overcome by the use of nano aluminium, but perhaps not. Other idea might be urea-peroxide adduct for use in propellant, don't know if it has been mentioned before and possible compatibility issues with aluminium powder (wouldn't directly think so), it is rather easy to make though. May need some down-tuning to prevent explosion instead of burning though. https://en.wikipedia.org/wiki/Hydrogen_peroxide_-_urea [Edited on 10-11-2015 by nitro-genes]

I checked Nakka experiments and found him using : Aluminum (atomized powder <60µm from Axson Technologie)

if he would use nano Al he would have better performance and the results might change but this won't solve the challanges of AN :
1-hygroscopic nature
2-known to be very hard to ignite
3-experiences phase change at room temperature which means that it cannot be stored it in an easy way


Hydrogen peroxide urea would explode because of the very high temperature and pressure generated inside the rocket motor !

hmmm I was thinking now in a funny way. since Al and water is a propellent then AN+Al+water would be better propellent. the hygroscopic nature might be an advantage here

[Edited on 11-11-2015 by ecos]

Very good idea, compared to ALICE, a flash frozen (liquid N2 or something) ammonium nitrate/nano aluminium propellant might be even better! In case of a flash-frozen ammonium nitrate emulsion type composition (used in mining) +aluminium, the propellant may have increased storage stability as well, even at RT and could be moulded into the shape and then flash-frozen before launch.

The hygroscopic nature is also something encountered for regular RC propellant, although sucrose is non-hygroscopic, the heat treatment leads to formation of mono saccharides, which do absorb moisture from the air (rel. humidity over here us usually around 80-90%), when corn syrup is used to control crystal size, the propellant is incredibly hygroscopic. I used to store it in sealed glass jar with silica gel to prevent this, same way I store my finely powdered AN. According to some patents, the phase change of ammonium nitrate can be prevented by a small percentage of zinc salts IIRC, something I have never tried.

I would think that a nano aluminium/AN propellent instead of 60 um atomized would lead to better ignitability and higher burnrates. Though these guys probably had a good reason to use atomized, thinking flake Al may lead to very unpredictable propellant behaviour, depending on the batch of aluminium used.

[Edited on 11-11-2015 by nitro-genes]

Quote: Originally posted by deltaH

I think some here are underestimating the power of nano-aluminium. If you want to see just what these nanometals can do in combination with oxidants, see our very own dornier335a: https://www.youtube.com/channel/UC6SItJwaTE3jawp-wGNKPBQ Urea and pyroaluminium... ok Urea and nanoaluminium... ehhh... maybe ok? Peroxide or AN and nanoaluminium... BOOM! [Edited on 11-11-2015 by deltaH]

Quote: Originally posted by PHILOU Zrealone

NH4NO3 solution will chew through the Aluminium powder in less than a few days!

I don't if Al would react with AN as you stated but I think under low temperature this reaction may stop. ALICE depends on low temp to stop the reaction between water and Al.

I am not sure if Temp < -80 is logical. I thought about -10 degrees but not -80

I have a question here , solution of Ammonium hydroxide ([NH4+][OH−]) would be much better than water since the earlier has Nitrogen and excess hydrogen.
would that work ?

[Edited on 13-11-2015 by ecos]

Quote: Originally posted by nitro-genes

yes, normally it would, I was thinking maybe in an W/O emulsion type propellant it may be more storage stable, then again...it is unlikely the nano Al will only stay in the wax-dispersion phase. Another question is how fast the reduction of ammonium nitrate happens at -80 deg C or so, since we are talking about (presumably) amorphously frozen propellants, hence <-80. Another thought: Magnesium powder can be coated with chromates to make it less prone to surface oxidation, similarly, IIRC, some chromates added to ammonium nitrate solutions can strongly inhibit corrosion for several aluminium alloys. A combination of these three factors may be enough to virtually eradicate the nitrate-Al problem.

Chromates are activators for sensitization of NH4NO3...so a CATO (deflagration or detonation) of the propellant is to be expected.

Yeah nothing is that simple in chemistry .

Quote: Originally posted by ecos

Quote: Originally posted by PHILOU Zrealone   NH4NO3 solution will chew through the Aluminium powder in less than a few days! I don't if Al would react with AN as you stated but I think under low temperature this reaction may stop. ALICE depends on low temp to stop the reaction between water and Al. I am not sure if Temp < -80 is logical. I thought about -10 degrees but not -80 I have a question here , solution of Ammonium hydroxide ([NH4+][OH−]) would be much better than water since the earlier has Nitrogen and excess hydrogen. would that work ? [Edited on 13-11-2015 by ecos]

Quote: Originally posted by ecos

I used to add 5% charcoal in ball mill to avoid oxidation of Al. Now I would run my ball mill for long time to prepare nano-Al. would 5% charcoal be suitable to cover the nano-Al particles ?