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UncleJoe1985
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[*] posted on 26-10-2008 at 14:58
ammonium nitrate rocket fuel


Does anybody have any experience with NH4NO3 based rocket fuels? I've tried using sugar as a fuel, but rarely had any success setting it off. It seems the mixture drowns under the water produced when the nitrate decomposes. I know that AN has been successfully used in large rockets (one used magnesium powder as fuel).
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DeAdFX
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[*] posted on 26-10-2008 at 15:11


The water generated by the decomposition of ammonium nitrate doesn't drown it. Check out richard naka's work on AN rocket fuel. He recommends Al powder/S/AN/Binder. Mg works but costs alot because it is shipped w/ 50% powder and I think their is a haz mat fee tacked on too.
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kclo4
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[*] posted on 26-10-2008 at 15:21


Ammonium Nitrate is also hygroscopic, which might explain why it is rarely found for such uses, I guess that causes some problems. Anhydrous Ammonium Nitrate would most likely work the best.
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UncleJoe1985
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[*] posted on 26-10-2008 at 15:34


Awesome, I've known about his work before, but haven't seen this page before since it was posted only a few months ago. I'll take a look.

[Edited on 26-10-2008 by UncleJoe1985]
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franklyn
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[*] posted on 26-10-2008 at 16:37


There is a Yahoo group on this worth a look.
http://tech.groups.yahoo.com/group/NO3-propellants

.
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[*] posted on 30-10-2008 at 05:46


Here is what I fond on Rogue Science, its Mr. Cool's and NOT mine.

Mr Cool
I've used an AN based fuel, it was:

Ammonium Nitrate..............70% [fertiliser grade]
Powdered Aluminum..............5% [resin additive]
Polyester Resin...................18% [cheap stuff for fibreglass work]
Ammonium Bichromate..........5% [actually, potassium dichromate was used]
Powdered Charcoal................2% [lumpwood barbeque charcoal, reduced to airfloat in a ball mill]

It worked, but was not as good as KNO3/sugar or BP. I only tried a few times, maybe with practice it could be improved, or maybe with a different motor design.
IIRC, it hardly burnt at all in the open, just the resin with a smokey flame. I used a small nozzle and a BP igniting charge up the core to try and get the pressure up.

Another AN mix which apparently works is very simple: 80-90% AN, 10-20% "urethane plastic."

I remember he tried it in a Gyrojet (spin stabilized, canted ports) rocket, and it gave massive thrust and power. I an going to try it once I build a metal engine and get my (NH4)2Cr2O7 (I think thats the formula... Its Ammonium Dichromate.) The Ammon. Dichromate decomposes to mostly gas and some Cr2O3. An excess of Al powder should act as an in situ 'Thermite' reaction, via Cr2O3 + 2Al = Al2O3 + 2Cr. Not sure if the reaction is correct but here is a link to a video of said thermit:
http://www.nakka-rocketry.net/thermites.html#TH9 and it works w/ Mg also. I will be using MgAl in my engine. The prime will be BP in the core.

Here is Mr. Cool's post on its performance:

I made a 1" diameter rocket stabilised using angled jets. I used a paper roll cap to set it off, and BP with a bit of red phosphorous as an igniter because I didn't have any primers. The fuel was AN/Al/resin/ammonium dichromate/charcoal (actually I used potassium dichromate), as described in ALENGOSVIG1's site. I launched it from a cardboard tube with a nail in the bottom. The rocket was put about 1" into the tube, where it was stopped by a nail through the side. A length of string attached to this nail could be pulled from a distance, allowing the rocket to fall and be set off. It went very high very fast, and very straight.

I may copy said rocket exactly as described.

This is his description of how to make the body:

In my opinion, it would be worth making the ammo (not very hard) for an improvised weapon because of these points. For the (very basic) ammo, just get copper tubing, seal one end with epoxy, fill it with a composite rocket fuel, and plug it with a disc of anything easily drillable and fairly strong, e.g. MDF. Then, using a jig, drill a central hole through the rear plug, and two small angled holes opposite each other on either side of the larger, main hole. Pour a little bit of BP in through the main hole, seal the other two holes with molten wax, and push a rifle primer in the main hole.
Once everything is set up you could mass produce these very quickly. It wouldn't matter if the MDF burnt, because by the time it had burnt a significant amount the rocket would have hit the target.

All credit to Roguesci and Mr. Cool for this post.




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Liedenfrost
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cool.gif posted on 20-11-2008 at 22:40


A friend of mine living in Eastern Europe is having good results with an AN and Aluminium based propellant.
Here are some details of his propellant:


AN - 60% fine ground (unknown mesh ball milled Fert grade prills)
Al - 20% 50 micron
Neutral (sanitary) silicone - 20%

Isp=239s at sea level.
Density - 1,66g/cm3
a=0.0273
n=0,338
r=1,3mm/s open air
Pressing at relatively low pressure /500-600kg/cm2 / or ramming
Mechanical strength is quite low.
This fuel was tested in motors up to 38mm with great results.

Notable things about this propellant is that it works very well in a vast range of Kn=100-300 and where the pressure is from 1MPa to 5Mpa and burning is stable.
The combustion temperature is very high /2800*C/ and graphite nozzles or inserts are needed.Also powerful igniters are required for good ignition, He's been using Nakka's ''spit fire'' igniters, come to think of it, Nakka is working on AN and Aluminium propellant over on his site.





My friend uses FGAN /fertilizer grade 34-0-0/ ,granulated. It consist 0,5% MgO as a stabilizer according to the information provided by the local manufacturer.

[AN is in the form of rhombohedral crystals at room temperature but changes to monoclinic crystals (larger) when heated above 32 degrees Celsius]

I've been in contact with him since and he has this to add:

''New formula AN,SI,AL. 3N
AN - 67%
NN* - 3% /Sodium nitrate/
Aluminium - 18%
Neutral silicone - 12%

*My friend is from eastern Europe and so NN=''natrium nitrat'' IIRC.

In a small motor 25x150mm with 60g propellant.
Kn value was on the low side ~100.
My small rocket flew seemingly well with burning time around 4s.''

Heres a video that he made of this different propellant.

http://www.youtube.com/watch?v=ZzaL0r1LwXQ''


The mixing process of AN
- I grind the granules up to 0,5mm size
- I dry it in oven at a temperature 90-100*C for about 2 hours
- I grind finally the granules up to 50 microns
- I mix the silicone with Al first,then i add the AN from above
Commence long stirring by hand until it moves from wet sand consistence to thick paste.
The Mixing process is a big challenge,but not impossible.
Pressing by hand or ramming directly to the motor case.
I leave it to cure overnight and then I carefully and slowly drill a core.

In the other formula's 70/20/10 or 70/18/12 with less silicone content,
I drill immediately without waiting for curing.

I use this propellant in small motors up to 38mm without any problems with phase changes of the AN.



Silicone N has much better oxygen balance than HTPB. It releases oxygen with hardening which compounds are very efficient depressants of the exponent ā€œnā€.
(I'm not sure what he's trying to say here sorry).

Here's a picture of one of the grains.

[IMG]http://i8.photobucket.com/albums/a30/sequesteredfishy/ANSIAL.gif[IMG]

The aluminum was about 20-30 microns.

I'm sorry if there are grammatical mistakes in this post[I can not think straight right now, too much grog]
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[*] posted on 2-9-2010 at 23:09


Hey Liedenfrost,

I found the video on youtube before I saw this post on the forum. Currently, I am investigating the use of AN as an oxidizer in rocket propellants and I am very curious to the details of this particular propellant. Could you get me into contact with your friend?
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grndpndr
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[*] posted on 2-9-2010 at 23:56


The use of AN in various rocket propellants is very exciting! Im anxios to make a file of whats available and read at my liesure.
sadly AN isnt available in the quantity or quality it used to be at least anywhere near here.:(
Where there a will thers a way however.
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DubaiAmateurRocketry
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[*] posted on 7-6-2013 at 03:40


If you use Ammonium Nitrate and Sugar, great, your ratio must be wrong.

Because amminium nitrate sucks at donating oxygen, 2NH4NO3 decomposes to give only one Oxygen gas molecule, which is terrible.

You will need at least 80% Ammonium Nitrate by weight in your propellant if your fuel is sugar.





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papaya
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[*] posted on 7-6-2013 at 04:33


I'm not interested in rockets, however I want to add something interesting I did after some time from opening https://www.sciencemadness.org/whisper/viewthread.php?tid=24...
thread. I'm still looking for AN/fuel/catalyst combination which will burn well under atmospheric pressure (initially wanted to achieve some composition for fuses, without Al or Mg powder). One of experiments was : melted AN with urotropin (8%), when cooled the flakes of that would burn vigorously if placed on Al foil and heated. Later I ground it and added some 5% Cr2O3 catalyst, mixed into rubber glue(chlorinated rubber I think), however glue never hardened since the composition is extremely hygroscopic and becomes WET in open air, but even then it burned quite well. How I came to it is: chromium is a catalyst for AN decomposition, and is also a catalyst for urotropin burning (put some Cr2O3 on dry fuel tablet, ignite, wait to heat it up, then blow the flame - you'll see it continues to burn like cigarette), so it will work both for fuel and oxidizer. I suspect Cr2O3 can catalyze any amine burning reaction as it works also for ammonia gas oxidation. As I said the product made this way is extremely hygroscopic, may be replacing urotropin with urea/other amines/amides may give better result, I cannot test that since have no compounds yet, what do you think?
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Antiswat
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[*] posted on 7-6-2013 at 04:41


well the water absorbed through air could yield some extra power (ALICE project using ''nano'' aluminium dust and water frozen down)
you might want some very hot initiation source for this somehow




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DubaiAmateurRocketry
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[*] posted on 7-6-2013 at 05:07


Quote: Originally posted by Antiswat  
well the water absorbed through air could yield some extra power (ALICE project using ''nano'' aluminium dust and water frozen down)
you might want some very hot initiation source for this somehow


Nano aluminum, its so hard to make, and you have store in a noble gas can, Aluminum oxide forms around 25 Nano meter so any contact with our atmosphere will screw ur aluminum up for that reaction. The reaction temperature isnt that high and a good thermite could do it.




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