Sciencemadness Discussion Board

Ammonium nitrate as propellant

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ecos - 16-2-2015 at 02:16

Hi All,

there is a part of the discussion of this topic under a name of "nitrocellulose help" but the initial topic is already different and the name became miss leading. I would prefer to have a separate thread for this topic.

I went through Nakka project : http://www.nakka-rocketry.net/anexp.html#preparation

he stated that the promising mixture is A24 : 68% AN , 4% S , 17% Al , 11% binder (Neoprene)

He also stated in his website regarding the binder :

Quote:

Early experiments performed by the author confirmed that AN mixed solely with typical fuel/binders such as epoxy, sucrose, polyester, polyurethane and silicone would generally not sustain combustion. If a small amount of NaCl were incorporated, sustained burning (smouldering) would occur, however, very slowly, and the resulting low combustion temperature would tend to produce voluminous amounts of carbon-rich ash.


but Nakka never made any tests with those binders in his table.

I also found another formula for Wickman Propellant: http://www.space-rockets.com/prop.html

My problem is with the binders !! specially R45HT binder. it is hard to synthesis.

I found interesting article for optimization over Nakka project : https://www.byui.edu/Documents/physics/Theses/David_NeweyF13...

they used this formula but they didnt state the binder ! : 74.9% AN, 19.8% Al, 6.5% S and the rest is a binder.

I found this equation in the article above , I wonder if he used benzene as a binder?!



do anybody have a successful experiments with AN but with simple binders?

i think this book has many experiments regarding AN and AP : "How To Make Amateur Rockets" but I couldn't find a copy for it.


[Edited on 16-2-2015 by ecos]

PHILOU Zrealone - 16-2-2015 at 05:50

Benzene is too volatile and labile to be a binder it must be a typo.
Not counting the carcinogenic and flamability risk involved with its use.

hissingnoise - 16-2-2015 at 06:29

Quote:
My problem is with the binders !! specially R45HT binder. it is hard to synthesis.

You can get it here!


TGT - 16-2-2015 at 17:02

In some countries they use the name benzene to mean white fuel, or coleman fuel. Could they mean that? Just a suggestion...

DubaiAmateurRocketry - 16-2-2015 at 17:25

AN is clean and alright, the problem with it is that its hard to ignite, low OB, and u better have a good catalyst, magnesium works well with AN.

ecos - 17-2-2015 at 02:34

Mg is expensive material thats why Nakka prefered to use Al:


Quote:

The drawbacks to using magnesium as a constituent in a propellant include the safety concerns associated with handling, the high cost of this material (especially when hazmat shipping fees are factored in), and the lack of easy availability.

After much pondering, a rather interesting alternative thermic agent came to light. Aluminum, which has a greater heat of reaction than magnesium, was then tried. The difficulty with combusting particles of aluminum is due to the tough shell of aluminum oxide (alumina) that encases the readily oxidized metal. Initial attempts at simply blending aluminum powder with AN and a binder were fruitless. The aluminum particles did not burn satisfactorily, being well protected by the tough alumina shell. Reference [4] also describes attempts at using powdered aluminum, but the studied formulations failed to burn.




DubaiAmateurRocketry - 17-2-2015 at 23:57

you can try it, but aluminum barely burns because the temperature AN burns at is just not enough to totally utilize Al2O3's high energy out put.

Bert - 18-2-2015 at 00:12

Of course, there are Aluminum-Magnesium alloys. Popular in pyrotechnics, available from suppliers in various ratios and a wide range of particle sizes and shapes.

A 50:50 by weight alloy of Mg-Al poured onto a cold Iron or steel surface shatters like ice. It can be easily reduced in a ball mill to very fine particle size, I recall Dutch amateur pyrotechnists doing this and writing a "how to" article during the 1990's. Key is technique to smelt without setting it on fire, and pouring the alloy at just above melting point to prevent it igniting.

http://m.instructables.com/id/7030-MgAl-Magnalium-Powder-Pro...

[Edited on 18-2-2015 by Bert]

violet sin - 18-2-2015 at 01:09

random thought just before bed, so probably a bad one.. but in OP it stated that NaCl helped burn rate/sustainability but not much, and also that benzene was used as/in the binder. perhaps a typo, but made me think of mothballs, or more specifically p-dichlorobenzene. just a thought, prob a poor one

ecos - 18-2-2015 at 01:58

Quote: Originally posted by Bert  
Of course, there are Aluminum-Magnesium alloys. Popular in pyrotechnics, available from suppliers in various ratios and a wide range of particle sizes and shapes.

A 50:50 by weight alloy of Mg-Al poured onto a cold Iron or steel surface shatters like ice. It can be easily reduced in a ball mill to very fine particle size, I recall Dutch amateur pyrotechnists doing this and writing a "how to" article during the 1990's. Key is technique to smelt without setting it on fire, and pouring the alloy at just above melting point to prevent it igniting.

http://m.instructables.com/id/7030-MgAl-Magnalium-Powder-Pro...

[Edited on 18-2-2015 by Bert]


interesting article, i went through it and found the same statement :

Quote:

The hazardous nature of transporting these powders is currently causing shipping costs and restrictions to rise. The recent increase in security within the US and international delivery systems is making it difficult for rocketry hobbyists to purchase these powders at a low cost.


I found it interesting to use S to break the oxide shell of Al, both Al and S are cheap and easily found.

regarding : DubaiAmateurRocketry
Quote:

you can try it, but aluminum barely burns because the temperature AN burns at is just not enough to totally utilize Al2O3's high energy out put.

I am afraid of this point , I was thinking to add some iron oxide on the mixture , this would form Thermit and would increase the temperature in the chamber.
but it seems the articles i showed in my first post stated success with only Al and S and this sounds promising for me.
My problem now is the binder ! , shiping RHHT would be a big problem ! so it wont work.



[Edited on 18-2-2015 by ecos]

ecos - 19-2-2015 at 03:55

do anybody have access to this article : http://www.readcube.com/articles/10.1002%2Fprep.201200159?r3...

Microtek - 19-2-2015 at 13:50

AN can form the basis of a very powerful rocket propellant along with aluminum and silicone rubber as a binder. There is a thread here on SM from some years ago about that (this is where I first saw it). The resulting grain is a little difficult to ignite, and gives a quite sedate burn in the open, however, it performs excellently (and smokelessly) in an actual motor. In addition it is very tolerant and works well with a variety of Kn ratios without CATO or "puffing". The original poster felt that this was due to the nature of the binder, giving a quite low n-exponent (in the dependency of burn rate on pressure, IIRC).

I modified the propellant by adding granulated NC/NG and also improved the mixing procedure by utilizing an inert solvent to get a more uniform material that could be processed into a molding powder. Using these modifications I made 12 mm rockets that performed very much like the old gyrojet, though the sound was much more pronounced.

ecos - 20-2-2015 at 06:04

Hi Microtek,

I found the propellant you mentioned but with AP instead of AN : http://youtu.be/TllMf7DzYkA

I would try (AN + S+ Al + Silicone rubber + Fe2O3) but i still think about the percentages I would use.

ecos - 22-2-2015 at 13:16

I was reading about Sulfur and Aluminum and found this on wiki :

Quote:

Aluminium sulfide is readily prepared by ignition of the elements[6]
2 Al + 3 S → Al2S3
This reaction is extremely exothermic and it is not necessary or desirable to heat the whole mass of the sulfur-aluminium mixture; (except possibly for very small amounts of reactants). The product will be created in a fused form; it reaches a temperature greater than 1100 °C and may melt its way through steel. The cooled product is very hard.


for formation A24 : 68% AN , 4% S , 17% Al , 11% binder (Neoprene)

my understanding now , the 4%S would react with 2.2% Al to form very high temperature to disable AN from self-extinguished.
Thats why a high percentage of Sulfur didnt work for Nakka's project, i.e the sulfur reacted with most of Al and this make shortage for Al(fuel) to be reacted with AN(Oxidizer).

I wonder why didnt he use Fe2O3 instead of Sulfur to generate higher temperature to avoid self-extinguished?



[Edited on 23-2-2015 by ecos]

Microtek - 22-2-2015 at 23:19

Sulfur is not required if silicone rubber is used as the binder. As I said, it is a little hard to ignite (though not more so than many other propellants), but it exhibits a nice stable burn. At least if well mixed, with very fine Al and AN particles.

Trotsky - 23-2-2015 at 00:02

By silicone rubber you're talking about window seal or caulk? Never tried it.

ecos - 23-2-2015 at 00:40

Quote: Originally posted by Microtek  
Sulfur is not required if silicone rubber is used as the binder. As I said, it is a little hard to ignite (though not more so than many other propellants), but it exhibits a nice stable burn. At least if well mixed, with very fine Al and AN particles.


I found this mixture :



this means that elastomer binder is silicone rubber?

Microtek - 23-2-2015 at 03:15

I doubt that would work. AN mixtures do not burn well without a metallic fuel. Usually said metallic fuel has to be Mg or Mg/Al alloys to sustain the burn, but specifically in the case of siloxane polymers (silicone rubber), pure Al can be used.
Many kinds of caulk contain inert additives which is not good. Look at the MSDS of the product to find out wht is in there.

Bert - 23-2-2015 at 04:30

Clear GE silicone II has been used in other rocket fuel mixtures-

ecos - 23-2-2015 at 06:37

Thx all for the support , I think the improved Nakka formula is my target , very low Sulfur percentage and I would use silicone as binder
the mixture will be like this : 74.9% AN , 0.65% S , 19.8% Al , 4.65% Binder(GE silicone II)

I will try to make a grain and provide my feedback after testing.

ni3rtap - 23-2-2015 at 17:49

AN seems like a fairly terrible oxidizer for a rocket. If it has aluminum (or possibly with magnesium) Any moisture will liberate ammonia and decompose most of the aluminum over time. Boric acid or possible oxalic may help stop this. But you would have to have hardcore storage as well as phase stabilizing it to store it for much time.

Adding some silicon fuel seems like the best solution for keeping the reaction going. The little droplets of red of glass should keep the reaction going. Lol Though, you might as well use AlICE(aluminum Ice) propellent.




"""Blue Strobe Rocket

This is a relatively simple composition to make, but bizarre in its behavior and a mess to formulate. The basic formula is:

Blue Strobe Rocket Formula
Ammonium perchlorate 63%
Copper oxide, black 10%
PVC powder 5%
GE II Silicone #5000 (bathroom caulk) 22%

First, take the three dry ingredients (ammonium perchlorate (ball milled to a fine dust), copper oxide, and PVC powder) and sieve them together three times through a 40-mesh screen. Then, place them in a container on a balance and tare it. Slowly squeeze in the appropriate weight of silicone caulk. This requires some practice to be precise. Go slow and easy so as not to add too much.

Mixing requires some effort. I prefer to use an old plastic container. First I mix it with a fork as thoroughly as possible. Then, I use a wooden dowel, 1.5 inches in diameter by 6 inches long, as a pestle to try to force the strobe rocket mix through a window screen section stretched over a bowl. Not all will go through, but the kneading action will thoroughly mix even the congealed portion, which can later be grated through a wire mesh screen with 1/4-inch squares.

Some folks like to use a plastic bag of the Ziploc variety to manually knead the strobe rocket mix. I prefer not to be holding it! I always wear gloves and safety glasses when working with any pyrotechnic compositions. And, I sure don't want to make a mess of anyone's shop who is gracious enough to allow me to work in their facilities. This composition is so messy that I recommend you set aside a set of tools to use with this and with nothing else.

The composition is highly flammable as soon as it is mixed, so be careful. Use an arbor or hydraulic press, it is best pressed (do NOT hammer or ram this composition!) into strobe rockets BEFORE it has a chance to set and cure. When it cures, it's like working with small pieces of pencil eraser. Try making cut stars before the mix cures. Or, try pressing the soft composition into tubes for strobe pots and letting them cure overnight.

The composition actually burns quite slowly. Try burning some on the ground, outside a tube to see this effect.

There are many types of silicones. Different curing systems are employed. Some may not be compatible with the other chemicals used. I do not recommend any but the most cautious experimentation with any other silicones. Further, if you place a small amount of composition on a steel plate and hit it with a hammer, you will find it is also shock sensitive.""""http://www.skylighter.com/fireworks/How-to-make-sky-rockets/blue-strobe-rocket.asp

ecos - 24-2-2015 at 01:11

Hi Ni3rtap, Thx for the reply.

My problem is with ammonium perchlorate, it needs electrolysis with MMO plates which is a headache for me to find. the electroanalysis process takes around 7 days with a strong power supply.

AP is sensitive and I found many accidents with it. a boy lost his hand when he tried to modify something inside the rocket motor.

I would prefer AN since it is easily found (fertilizer , cold backs, ....) , cheap , low sensitivity.

I didnt search yet about kinds of silicone in nearby markets, I will try to find what is available and then check them online.

anyway , thanks for the info and i would keep this composition in mind :)


Bert - 24-2-2015 at 06:12

ecos, you are in Eastern Europe?

Ammonium perchlorate sensitivity to detonation (and burn speed in a fuel) is closely tied to particle size- AP below a certain mesh size is shipped as a high explosive rather than as an oxidizer in USA. The suppliers to hobby rocket motor builders specify mesh size, and some even tumble the grains to produce rounded, more regular shapes.

See here:

http://www.firefox-fx.com/ChemA.htm

ecos - 24-2-2015 at 07:40

Hi Bert, I am in CE but what is the aim of this question ?

what u stated about AP is the reason why i avoid it.

Bert - 24-2-2015 at 08:23

Where you are located has a lot to do with what chemicals you can easily buy.

CE? No clue.

Have you ever built a rocket motor?

ecos - 24-2-2015 at 12:17

I always use PVC pipes,i follow these steps: http://youtu.be/12fR9neVnS8

You will find a compressing stage using a hammer in the above video,Thats why i want to avoid any sensitive composition.

[Edited on 24-2-2015 by ecos]

PHILOU Zrealone - 24-2-2015 at 14:44

Quote: Originally posted by Bert  


CE? No clue.


EC = European Community
CE = Communauté Européenne
Thus the same ;) but with a french touch :D

jock88 - 24-2-2015 at 15:14


Is the second one not arabic?

ecos - 24-2-2015 at 15:17

My concern now is the binder percentage. Nakka's project used 11% binder. The improved formula uses around 5% binder.

Most of papers uses high percentage of binders like :http://www.eucass-proceedings.eu/articles/eucass/pdf/2009/01/eucass1p81.pdf

How could i calculate the correct % needed for my composition?

PHILOU Zrealone - 25-2-2015 at 04:55

Quote: Originally posted by ecos  
My concern now is the binder percentage. Nakka's project used 11% binder. The improved formula uses around 5% binder.

Most of papers uses high percentage of binders like :http://www.eucass-proceedings.eu/articles/eucass/pdf/2009/01/eucass1p81.pdf

How could i calculate the correct % needed for my composition?


In Brico shops inside Europe, there are some "silicone like cartige" of polymer glues (Power Fix and the like) wich display very good combustion on their own. By determinating and calculating the centesimal composition of those polymer, you may find the best OB ratio and thus determine the ideal % of binder.
Note that silicone doesn't burn completely or well because of the inert SiO2 resulting from its combustion... the SiO2 formed often prevent further burning and flame propagation into the silicone mass. It is like glass coating forming at the surface.

Bert - 25-2-2015 at 07:18

PLEASE! DO NOT MIX A LARGE BATCH OF ROCKET FUEL WITH CYANOACRYLATE GLUE!!!

The reaction that cures these glues is EXOTHERMIC.

Take a cotton ball and dump a bottle of "super glue" on it. Check out how the temperature rises

Do you want to have a thermal runaway in a fuel grain? Maybe inside a metal mould, just to increase the fun...

ecos - 26-2-2015 at 04:02

Thanks for the precaution Bert.

I would like to understand something, If I used Thermite for ignition , why doesn't the compositions explode?
The detonation temperature of AN is 500 degrees and thermite would generate more heat than this.

Bert - 26-2-2015 at 05:43

I am going to perform a little experiment- I've some dry lacquer grade commercial nitrocellulose, very fine powder. And a bottle of cheap dollar store cyanoacrylate glue.

The YouTube videos of cotton balls catching fire when saturated with superglue are apparently "improved", I am interested to see if dry NC will truly ignite unconfined when saturated with superglue.

Cotton ignites about 255 C, nitrocellulose about 170 C. I will report results-

ecos - 27-2-2015 at 01:58

@Bert, Looking forward for your results.

Quote: Originally posted by ecos  
Thanks for the precaution Bert.

I would like to understand something, If I used Thermite for ignition , why doesn't the compositions explode?
The detonation temperature of AN is 500 degrees and thermite would generate more heat than this.


in addition to this question , do I need to use PSAN-I instead of AN for my composition or silicone would be enough to make phase stabilization as well ?

Ref : http://www.wickmanspacecraft.com/psan-i.html

[Edited on 27-2-2015 by ecos]

Fulmen - 27-2-2015 at 03:56

AN doesn't detonate at 500°C, in fact the combustion temperature is probably in the 1500°C range.

Bert - 27-2-2015 at 06:46

Quote: Originally posted by ecos  

I would like to understand something, If I used Thermite for ignition , why doesn't the compositions explode?
The detonation temperature of AN is 500 degrees and thermite would generate more heat than this.


AN mixtures near STP generally require a shock to detonate, often needing a booster explosives as well as a blasting cap . AN decomposes FAR slow 500 C, around 210 C.


Quote:

in addition to this question , do I need to use PSAN-I instead of AN for my composition or silicone would be enough to make phase stabilization as well ?



You only require phase stabilized AN if you are going to store fuel grains or grained propellant powders at fluctuating temperatures, the upper transition temperature which typically causes the grains to break up is about 32 C. There are other methods to reduce the cracking of case bonded fuel grains from temperature cycling as well-

http://www.google.com/patents/US2957309

For an experimental rocket motor made in a European winter, stored at indoor temperatures and fired soon after production, phase stabilization is probably not required. If you need to keep the motors for months or years in an outdoor magazine in the summer sun, where the fuel crosses the transition temperature twice a day? You would need to deal with the phase change.


[Edited on 27-2-2015 by Bert]

ecos - 27-2-2015 at 08:27

Quote: Originally posted by Fulmen  
AN doesn't detonate at 500°C, in fact the combustion temperature is probably in the 1500°C range.


I think AN detonated around 300 degrees : https://www.youtube.com/watch?v=GxKXAbS7WAo

Bert - 27-2-2015 at 10:57

I think that pointing a blow torch at an oxidizer sample on a brick with unknown composition/contaminants and no instrumentation doesn't = precise information.

Fulmen - 27-2-2015 at 14:24

Short answer: No.
Long answer: Hell no! :P

As Bert put it, one murky video off Youtube does not represent good data. Trust me, it's called rocket science for a reason. There is a ton of information freely available on the net that will explain this in detail, but it takes time and the proper fundamentals to understand them.

Don't believe me, go see for yourself. Both the suitability of AN propellants, their performance and explosive properties can be found, and they will tell you that we're right.

And if I might speculate a bit, this "detonation" seems like just the thing you could get by heating a brick with a blowtorch. Rapid heating of a brittle material with low thermal conductivity can create "explosive" cracking.

[Edited on 27-2-15 by Fulmen]

ecos - 2-3-2015 at 01:39

sorry for using youtube as reference.

I went through some articles that discuss "polymeric binder"

Quote:

since hydrogen has higher combustion energy per unit weight than carbon, a hydrocarbon with high H/C ratio is preferred


silicone according to this statement is not the best.

i also noticed found that epoxy has higher H/C ratio compared to Neoprene !

epoxy is very hard when it is dry and Neoprene-contact cement is also very solid

any suggestions ?

[Edited on 2-3-2015 by ecos]

Bert - 2-3-2015 at 06:42

What mechanical characteristics does your motor design/performance/fuel grain require?

Answer that, and you can decide if you'd like a soft rubbery grain, or rock hard-

As an example, some people I know of who mere making larger and larger motors for very high acceleration applications started to have mid air catastrophic engine failures (KABOOM!). The fuel that had been well suited for the smaller engines was TOO soft and rubbery, was slumping under 100's of G acceleration, pulled away from the motor walls and exposed the grain outer sides to the flame- Too large a surface area burning, engine blows from over pressure.

Similarly, you may have a failure if you make a hard, brittle grain and crack it from handling or temperature cycle induced expansion/contraction.

Fulmen - 2-3-2015 at 08:13

Agreed. While a high H/C-ratio might increase performance it is of little interest if the mechanical properties suffer as a result. A suitable burn rate is just as important, especially with AN propellants which require a high Kn even under the best of conditions. And then you have to consider cost and availability, the best choice for you might not be the one with the highest performance.

ecos - 2-3-2015 at 09:28

very interesting.

I am planning for small grains most likely for fireworks. max 100 meters high.

Nakka used Neoprene-based contact cement as a binder. he should have a strong grain but it seems due to volatile materials there were tiny pores which affected the performance so he used another method.

Quote:
Since an appreciable percentage of the contact cement is volatile solvents, the resulting grain would unavoidably have very tiny pores. This was recognized as a potential downside, however this technique was considered to be a viable method, at least for initial testing. Since the AN / Aluminum formulations are difficult to ignite, it was felt that even though hot combustion gases could seep through the tiny pores, the affected material would not actually ignite. Test firing of motors prepared in this manner supported this hypothesis. A couple of such test motors were fired. Although hard to ignite, combined with erratic burning, the results were nevertheless encouraging. This method of grain production was soon dropped, however, due to lengthy time required for a grain to "dry". It was found (by regular weighing) that weeks were needed to get a solvent-free grain.

After pondering various ways to purge the solvent in an efficient manner, it was found that the most effective way was to drive out the solvents prior to forming the material into a grain. Once completed dried, which would only take a few hours if heated slightly, it was found that breaking the dried material up into small granules and then compressing them, that a surprisingly robust grain resulted. This basic method has since been employed for all subsequent motor grain preparation


I don't think the result grain would be as tough as epoxy !

Bert - 2-3-2015 at 10:33

If you just want consumer fireworks rocket level of performance, you are WAY over thinking this. Black powder, cheap, simple, requires only minimal and easily home made tools.

It is perfectly fine to explore higher performance fuels and their design parameters, and learn everything you can, of course! Especially, learn your design THEORY.

Eventually, one leaves the drawing board or books behind and tries an experiment. At that point, simpler and less demanding techniques that can be easily made to WORK may start to look much more attractive...

ecos - 4-3-2015 at 14:26

Totally agree :) but black powder is an issue to buy thats why i prefer AN

i am almost ready with the things i have , I have AN, Al powder , sulfur , binder

those are the binders i found in my hardware store :
1- RTV Silicone
2- Epoxy like : http://www.bison.net/en/products/647-2-components-adhesives/...
3- CPVC cement(it contains : tetrahydrofuran 109-99-9, methyl ethyl ketone 78-93-3, cyclohexanone 108-94-1)

could any body help regarding which one should i try?

[Edited on 4-3-2015 by ecos]

ecos - 4-3-2015 at 16:40

I couldnt stay much , i already tried the RTV silicone

I started with 5% binder but it was not enough , i started to increase till i reached this ratio :

AN : 59 %
Al : 16 %
S : 0.7%
Binder : 24%

it seems i increased the silicone too much :(

my samples :


they don't look nice but you can say my first trial with AN :)
I left them to dry and tomorrow i will drill a hole for testing the burning rate.


[Edited on 5-3-2015 by ecos]

[Edited on 5-3-2015 by ecos]

Bert - 4-3-2015 at 17:05

1: If you have access to ammonium nitrate, Potassium carbonate (wood ashes!), charcoal and Sulfur- Why do you think you need to BUY black powder? Making this is not difficult, or more dangerous than some of the other fuels you have contemplated...

2: If you simply MUST use AN, have an hydraulic press and a support sleeve, it is possible you need no binder. Amonpulver grains for artillery use were made in hydraulic presses with nothing but ammonium nitrate and charcoal, although some formulations contained small amounts of Sulfur .

Please see Tenney Davis: Chemistry of Powder and Explosives in the library for more information on amonpulver.

http://library.sciencemadness.org/library/books/the_chemistr...

ecos - 5-3-2015 at 02:28

Thx Bert,

I will give amonpulver a try but I need to close the story of the samples I prepared.

for the ignition , I couldn't find CuO to prepare CuO/Al :( , I have Zn dust and Sulfur. would it work ? I think to use mini bulb for a sample of 2 grams of Zn+S as igniter charge. what do u think ?

[Edited on 5-3-2015 by ecos]

[Edited on 5-3-2015 by ecos]

Bert - 5-3-2015 at 06:04

Manganese dioxide from carbon battery with Aluminum powder makes a thermite, or you could spend half an hour looking at the Copper chemistry threads and learn to make your own Copper oxide.

The MnO2/Al thermite is also a rocket fuel with a specific impulse comparable to black powder, which may be compacted into a motor casing with hydraulic press, or even rammed with drift and hammer. Exhaust from such an engine includes gaseous manganese, which burns in air behind rocket, the light is blinding if fired at night. Don't make these in PVC tube unless you line it with something like carbon fiber cloth, and be aware the extremely hot Aluminum oxide in exhaust erodes pressed clay nozzles very quickly. If you use a sky rocket stick to stabilize, it WILL be on fire when it comes back down...



[Edited on 5-3-2015 by Bert]

ecos - 5-3-2015 at 07:34

Got it , I found some videos to support on youtube.

but whats wrong with Zn+S ?


Hennig Brand - 5-3-2015 at 09:00

Wikipedia has a good page on solid fuel rockets. There can be errors in Wikipedia pages, but they are normally mostly correct. If you require a more trusted reference, look further.

http://en.wikipedia.org/wiki/Solid-fuel_rocket#Zinc.E2.80.93...

"
Zinc–sulfur (ZS) propellants

Composed of powdered zinc metal and powdered sulfur (oxidizer), ZS or "micrograin" is another pressed propellant that does not find any practical application outside specialized amateur rocketry circles due to its poor performance (as most ZS burns outside the combustion chamber) and incredibly fast linear burn rates on the order of 2 m/s. ZS is most often employed as a novelty propellant as the rocket accelerates extremely quickly leaving a spectacular large orange fireball behind it."

ecos - 5-3-2015 at 09:10

Quote: Originally posted by Hennig Brand  
Wikipedia has a good page on solid fuel rockets. There can be errors in Wikipedia pages, but they are normally mostly correct. If you require a more trusted reference, look further.

http://en.wikipedia.org/wiki/Solid-fuel_rocket#Zinc.E2.80.93...

"
Zinc–sulfur (ZS) propellants

Composed of powdered zinc metal and powdered sulfur (oxidizer), ZS or "micrograin" is another pressed propellant that does not find any practical application outside specialized amateur rocketry circles due to its poor performance (as most ZS burns outside the combustion chamber) and incredibly fast linear burn rates on the order of 2 m/s. ZS is most often employed as a novelty propellant as the rocket accelerates extremely quickly leaving a spectacular large orange fireball behind it."


thx Hennig, I already aware about that but I dont intend to use it as propellant but as igniter

Hennig Brand - 5-3-2015 at 10:35

Apologies, I wasn't following the thread closely enough. How about thermalite fuse/igniter cord? It is very hard to obtain at this point from what I have heard, but it can be improvised. It is apparently very good for difficult to ignite rocket engines among other things.

http://www.brianredmond.net/dwilliams/thermalite/thermalite....

I have made something similar several times, just from what I had lying around. The copper wire core was obtained by stripping the insulation off of old telephone wire. I have made some with potassium perchlorate and chlorate and some with just chlorate. Some was made with magnesium powder and some with just fine flake aluminum. The binder I used was NC, because I haven't obtained other binders yet. It all worked well; some was hotter burning than others depending on the composition. Short pieces of this apparently work very well as rocket igniters.


[Edited on 5-3-2015 by Hennig Brand]

Bert - 5-3-2015 at 11:05


Quote:

but whats wrong with Zn+S ?


I have never used it for igniting hard to light rocket fuels- After reading of some accidents to people handling "micrograin" fuel, I never made any more of it, there are higher performance fuels with better safety. Never made any rockets larger than 1/4" bore with this, and even that was 40 years ago.

Zn + S fuel is more like a slow flash powder than a rocket fuel, from my very limited experience. It MIGHT work as an igniter, but I know from personal experience that the Copper or Manganese oxide + Al thermites have worked well as igniters, and that these can be regulated somewhat in burn speed & ignition sensitivity by changing the Al powder particle size & shape.

If you experiment, let us know how it does.

(Edit)

I have just found some very fine Zn powder in my chemical storage, of a type used in anti corrosion paints. Some years back, a professional painter had 50 lb. buckets of this that were punctured by a fork lift, he gave me the remaining material rather than try to salvage it and use it on a government bridge painting project- It appears to be just fine, not oxidized or contaminated. I will try to make time for a small experiment-

[Edited on 5-3-2015 by Bert]

ecos - 5-3-2015 at 14:13

great, I will provide results of my experiments soon , maximum after 2 days.

I forgot that I have sulfur and Al.


Quote:

Aluminium sulfide is readily prepared by ignition of the elements[6]
2 Al + 3 S → Al2S3
This reaction is extremely exothermic and it is not necessary or desirable to heat the whole mass of the sulfur-aluminium mixture; (except possibly for very small amounts of reactants). The product will be created in a fused form; it reaches a temperature greater than 1100 °C and may melt its way through steel. The cooled product is very hard.


I received my shipment now and it contains (Mg ribbon , activated charcoal , Fe2O3)

Since I have Mg ribbon , I can prepare Fe2O3/Al and this is good news.

regarding MnO2/Al , I found it on : http://www.nakka-rocketry.net/thermites.html#TH5

the most interesting that it can be ignited with a Mini bulb igniter. I will give it a try but I need to find a better source than carbon batteries :) .

I am very interested to try ammonpulver. charcoal that I received needs to be fine powder. I will use my coffee grinder for this purpose.

I went through the book you provided.


Quote:

Ammonpulver which contains no potassium nitrate—in a typical example ammonium nitrate 85 per cent and charcoal 15 per cent, or a similar mixture containing in addition a small amount of aromatic nitro compound is flashless and gives at most only a thin bluish-gray smoke which disappears rapidly. Rusch has published data which show that the temperature of the gases from the burning of ammonpulver (ammonium nitrate 80 to 90 per cent, charcoal 20 to 10 per cent) is below 900°, and that the ballistic effect is approximately equal to that of ballistite containing one-third of its weight of nitroglyccrin.
Ammonpulver has the advantages of being cheap, powerful,flashless, and smokeless. It is insensitive to shock and to friction, and is more difficult to ignite than black powder. In use it requires a strong igniter charge. It burns rapidly, and in gunnery is used in the form of single-perforated cylindrical grains usually of a diameter nearly equal to that of the space within the cartridge. It has the disadvantages that it is extremely hygroscopic and that it will not tolerate wide changes of temperature without injury.


I tried to search about the Isp for Ammonpulver but couldn't find anything useful on internet. I also couldn't find much info about its power or different compositions with metal or sulfur.

any idea of different compositions ?

[Edited on 5-3-2015 by ecos]

ecos - 5-3-2015 at 17:07

the Mg ribbon is driving me crazy :( , when it touch anything while burning it stop!
the ribbon is made since 2009 , would that be a problem ?

I prepared a sample of ammonpulver (85% AN and 15% charcoal). I used Mg strip to ignite it.
the result is failure . here is a video : https://www.youtube.com/watch?v=4G5C28O2JQA

I had the similar behavior while trying to ignite S/Al !

any suggestions ?

[Edited on 6-3-2015 by ecos]

[Edited on 6-3-2015 by ecos]

Bert - 5-3-2015 at 18:46

That's pretty normal behavior for Mg ribbon- It loses heat to contact with solids or liquids, needs air to burn, won't behave like a fuse that has an oxidizer and easily goes out, very annoying!

Lots of lab manuals recomend igniting things with Mg ribbon. Very few experienced pyrotechnists have much use for it.

Please describe mixture ratios by weight and particle size for all reactants of your various mixtures that won't ignite...

ecos - 6-3-2015 at 01:54

The charcoal/sulfur/Fe2O3) are almost dust but Al is homemade using my coffee grinder (I cut the Aluminum foil into small parts and added some water then used my grinder to make it powder, after that i dried it)

the ratio was 85% AN and 15% charcoal

regarding my S/Al thermite , the ratio was 2:1

I used the grinder for AN and it is almost powder !

[Edited on 6-3-2015 by ecos]

Dornier 335A - 6-3-2015 at 05:28

My experience with ammonpulver is that it burns cleanly and with high gas output, but only if continuous heat is applied. This was for tests in the single-gram scale though, so a large, compressed fuel grain will of course work better. A little pressure won't hurt either.

ecos - 6-3-2015 at 06:07

how did you mix the An/C ? I use a tablespoon since i was afraid to use my coffee grinder :(.

Dornier 335A - 7-3-2015 at 01:51

I carefully milled them together between two steel plates. It might be relevant that I used high quality willow charcoal, the same as I use for black powder.

ecos - 7-3-2015 at 07:10

Ok , I took the risk and used coffee grinder to mix AN/C.

I made 10 trials to test AN/C using Mg ribbon , all the trial the ribbon didn't ignite the mixture, finally it gave smoke and thats it :( .

video : https://www.youtube.com/watch?v=YCmqHLsLjR8

whats wrong ?

[Edited on 7-3-2015 by ecos]

PHILOU Zrealone - 7-3-2015 at 11:51

Stop with Mg ribbon!

Use christmass sparklers :D
For me it works quite good to ignite thermite or other hard to ignite powders!

Beware that a single spark may set your powder pile in fire...so usually it is a good idea not to put the sparkler at the vertical on top of the powder...
--> Stick it at 30° from horizontal!

ecos - 7-3-2015 at 14:09

yes, I wish I can make sparklers, making KNO3 is very annoying using AN since ammonia gas kills me.

I am thinking about electronic igniter like this :



would this work with thermite? I can use copper wire instead of steel wool.


[Edited on 7-3-2015 by ecos]

Hennig Brand - 7-3-2015 at 15:36

I have used single strands of fine steel wool as bridge wires before I obtained a roll of fine nichrome. It does work quite well, I even did some rock blasting using igniters made with steel wool and never had a failure. Steel wool is often not very uniform; some strands can be weak in one of more places and break easily. A simple test is to select a strand and then put it under a bit of tension (pull on it), if it is too thin at any point along its length it will break. Once a strong, fairly regular, strand is selected it can be soldered to a pair of lead wires. A common fuse head composition is black powder with nitrocellulose lacquer binder, but it sounds like you need something hotter. You could do the first layer in black power and NC and then an outer layer of a hotter burning composition.

You could make electrical igniters with "Thermalite" composition type match heads. A friend of mine still has a couple of rolls of commercial Thermalite fuse and it really is wonderful stuff, very hot burning. It is not a core burning fuse, but it will still continue burning even if submerged in water from what I have heard. You would think I have stock in this company the way I am pushing this stuff. :D

Sparklers really do burn hot. I wonder how easy it would be to use a bit of sparkler as a component of an electric match head?


[Edited on 7-3-2015 by Hennig Brand]

ecos - 8-3-2015 at 00:53

black powder and NC ? :) Wow , it is more easier to make a bomb than making a rocket !

I think I can add Al powder to the steel wool , it would increase its efficiency for sure.




reference of the idea : http://www.thefintels.com/aer/noi.htm


ecos - 8-3-2015 at 03:19

I made my first test using wool and Al powder : https://www.youtube.com/watch?v=WcQg5cAVFVY

I think it is promising :) , what do u think ?

Hennig Brand - 8-3-2015 at 07:29

The electric match heads made of black powder bound in NC behave differently when lit than loose black powder or fibrous NC, they burn with a quick flash that isn't too violent. What you have done may work, but it is very crude. A more consistent and focused heat/energy source would be more desirable, such as a properly designed electric fuse head with suitably hot burning pyrogen. You want a lot of heat generated in a small volume and transferred to a small area (high temperature).

PHILOU Zrealone - 8-3-2015 at 11:30

Quote: Originally posted by Bert  

Quote:

but whats wrong with Zn+S ?

Zn + S fuel is more like a slow flash powder than a rocket fuel, from my very limited experience. It MIGHT work as an igniter, but I know from personal experience that the Copper or Manganese oxide + Al thermites have worked well as igniters, and that these can be regulated somewhat in burn speed & ignition sensitivity by changing the Al powder particle size & shape.

If you experiment, let us know how it does.

(Edit)

I have just found some very fine Zn powder in my chemical storage, of a type used in anti corrosion paints. Some years back, a professional painter had 50 lb. buckets of this that were punctured by a fork lift, he gave me the remaining material rather than try to salvage it and use it on a government bridge painting project- It appears to be just fine, not oxidized or contaminated. I will try to make time for a small experiment-

[Edited on 5-3-2015 by Bert]

Zn + S works as a rocket fuel because part of the Zn metal and Sulfur is vapourized by the reaction heat of Zn(s) + S(s) --> ZnS (s) and are responsible of the rocket thrust.
The vapourized Zn burns with a long pale blueish flame in the open air at the exhaust of the rocket...somewhat bluer flame for sulfur.
Orange colour comes from the cardboard, glue, ceramic that contains sodium, calcium impurities...
Zn(g) + 1/2 O2(g) --> ZnO (s)
S2(g) + O2(g) --> SO(g) + SO2(g) + SO3(g)

It is quite fun but it requires a lot of (sometimes expensive) powderous Zn by weight and it last so short.

Fulmen - 8-3-2015 at 12:32

It should be noted that An/S has a dodgy safety-record. IIRC it can be quite prone to static ignition, so do your research before playing.

As for ammonium nitrate propellants I think they are best suited for the experienced. While it is safe and has great performance at a low cost it isn't the easiest to work with. For the beginner there is really nothing that compares to BP or KNO3/sugar.

Bert - 8-3-2015 at 13:55

I recall an amateur rocketry hobbyist getting severely burned by a Zinc Sulfur rocket fuel accident. He was carrying a plastic bag of leftover "micro grain" fuel out to burn it off, and brushed the bag of fuel against a fence as he walked, which he believed drew a static spark through the powder.

His dog was walking with him, the dog got some very scorched fur too.

jock88 - 8-3-2015 at 14:31

There is some info. on Ammonpulver in COPAE.


Regarding Zn + S propellent I believe that the burn/reaction rate of the stuff is dependent on pressure in a strange way. When the pressure reaches a certain value the reaction rate stops increasing. This makes it east to make rockets cause if the chamber can withstand this max. pressure then it is impossible to have a CATO.

ecos - 8-3-2015 at 14:50

Quote: Originally posted by Hennig Brand  
The electric match heads made of black powder bound in NC behave differently when lit than loose black powder or fibrous NC, they burn with a quick flash that isn't too violent. What you have done may work, but it is very crude. A more consistent and focused heat/energy source would be more desirable, such as a properly designed electric fuse head with suitably hot burning pyrogen. You want a lot of heat generated in a small volume and transferred to a small area (high temperature).


I started to get headache from the nitration process , thats why i stopped synthesizing NC or NG.

as stated before , they only solution to get KNO3 is from AN, it is headache in preparation since ammonia gas has sharp smell

Black powder is not easy thing to buy in my country :)

After making the metal wool and Al powder work , I would prepare a sample of 1.3 grams of thermite around it to look like this :



I think this should work in the current time till i find a solution for KNO3 or BP

[Edited on 8-3-2015 by ecos]

ecos - 8-3-2015 at 14:59

Quote: Originally posted by Bert  
I recall an amateur rocketry hobbyist getting severely burned by a Zinc Sulfur rocket fuel accident. He was carrying a plastic bag of leftover "micro grain" fuel out to burn it off, and brushed the bag of fuel against a fence as he walked, which he believed drew a static spark through the powder.

His dog was walking with him, the dog got some very scorched fur too.


I was not planning to use Zn/S as propellant , It was just an idea to use it to ignite instead of thermite.

Bert - 8-3-2015 at 16:45


Quote:
as stated before , they only solution to get KNO3 is from AN, it is headache in preparation since ammonia gas has sharp smell.

Black powder is not easy thing to buy in my country



Probably best solution for KNO3 synthesis issue is a cheap fan and possibly a piece of cheap clothes dryer duct over reaction vessel, discharging ammonia fumes elsewhere.

If BP can not be bought in your country, what is the legality of making your own?

Out of curiosity, do you know your local laws regarding an individual making black powder, various types of solid rocket fuel and related energetic materials? It is better to know such things before the authorities bring them to your attention, especially when posting one's experiments online in an open forum. Are there officially recognized hobby rocket makers or clubs in your country? If not, maybe you could START one?

USA is pretty easy on legal issues related to amateur rocketry, as long as nothing gets damaged and no one is hurt (and you don't piss off your neighbors, local police, etc.)

But a kid from Scotland here recently spent some time arguing over being charged as a terrorist over making a KNO3 sugar rocket motor. It was a ridiculous charge, but annoying, time consuming & expensive in lawyer time for his parents all the same.

ecos - 9-3-2015 at 06:02

I will check my laws, I will also give it a try to synthesis KNO3 and make sparklers.

My tests of igniting Thermite or AN/C using metal wool and Al powder failed.

MnO2/Al in ratio 3:1 ------> https://www.youtube.com/watch?v=DYMvP3r2qwM

it seems I have a problem with Al powder but not sure, maybe it is a coarse powder :




you can maximize the picture by clicking on it.

[Edited on 9-3-2015 by ecos]

Bert - 9-3-2015 at 06:41

That is very coarse Al powder for the type of mixtures you are trying to make.

It is possible for an amateur to make pyro grade Al powder or Mg/Al alloys, do you know what a ball mill is?

http://www.rocketsaway.com/pyrotechnics_ball_mill_theory_spo...

http://pyrotechnic.narod.ru/Black_Powder.pdf






ecos - 9-3-2015 at 07:22

I just went through youtube and found ways to make black Al powder using Ball Mill
I still have to build it , I am going to make one using PVC as shown here : https://www.youtube.com/watch?v=4Hgs2MppTug&list=WL&...


The Al powder I stated in previous post was used in AN/AL explosives and i was expecting it work well.

PHILOU Zrealone - 9-3-2015 at 09:19

Quote: Originally posted by Bert  
I recall an amateur rocketry hobbyist getting severely burned by a Zinc Sulfur rocket fuel accident. He was carrying a plastic bag of leftover "micro grain" fuel out to burn it off, and brushed the bag of fuel against a fence as he walked, which he believed drew a static spark through the powder.

His dog was walking with him, the dog got some very scorched fur too.

At least he knows how to prepare a hot-dog :D. Was it a chinese guy ;)?

ecos - 9-3-2015 at 09:36

Quote: Originally posted by Bert  
That is very coarse Al powder for the type of mixtures you are trying to make.

It is possible for an amateur to make pyro grade Al powder or Mg/Al alloys, do you know what a ball mill is?

http://www.rocketsaway.com/pyrotechnics_ball_mill_theory_spo...

http://pyrotechnic.narod.ru/Black_Powder.pdf



The resource you provided is very useful , Thx.

the most interesting thing in the ball mill book :



ecos - 9-3-2015 at 18:04

Now I have the full picture of what i should do to get very fine Al powder or "German Al powder".

The missing question now, what is the percent of charcoal I need to add on Al to avoid hazards and mitigate risk ?

Most of the videos I found on internet state 2 spoons :) , this is not a technical info at all !

[Edited on 10-3-2015 by ecos]

The only statement I found in an article

Quote:

Carbon – If you are making dark aluminum powder, about 5% carbon (by mass)is added. This helps the powder from becoming hard over time. Graphite (a formof carbon) can be used along with this to help the powder flow better.


[Edited on 10-3-2015 by ecos]

Hennig Brand - 10-3-2015 at 10:04

I have made flake aluminum powder several different times in a 4" ball mill and it worked well. It did take a great deal longer than milling black powder though of course. Buying fine flake aluminum powder can be difficult for many. Supposedly the carbon coats the aluminum and prevents excessive oxidation during milling and during storage/handling before use. The carbon should also reduce the ignition temperature and increase the ease with which flame propagates through the fuel (I think).

IIRC I used 5% charcoal by weight, but I can't remember exactly what I was reading at the time that made me go with 5%. I don't imagine that the exact amount is all that critical, but most of the benefits are probably obtained with a small amount (few percent), also a small amount is better in the sense that it doesn't adulterate the aluminum powder as much.

ecos - 11-3-2015 at 07:03

I tried to search for Balls as a media , I think ceramic balls would need time to find it.
I also couldn't find metal/steal balls in neighborhood(the document recommends 1" or 0.5") but I found this :



is the size of this nut acceptable or I need smaller ones ? I plan to make 6" wide X 8" long PVC Jar. for the mill.

I know that metal/steal might make spark but I found some videos who used the same things : https://www.youtube.com/watch?v=nA94uHqUQvg

I think I need to modify the charge in the mill , The document stated 25% of the volume. I think I need more due to the more space that exist now.



[Edited on 11-3-2015 by ecos]

Hennig Brand - 11-3-2015 at 10:30

For milling aluminum I used 3/8" steel slingshot ammunition (steel balls), of course a mill drum larger than 4" and possibly larger steel balls would have worked better. For making black powder I used shotgun SSG shot (antimony hardened lead balls).


[Edited on 11-3-2015 by Hennig Brand]

Bert - 11-3-2015 at 11:08

As a child, I used several rolls of USA 5 cent coins in a 4" rock polisher drum ("Nickles", made of a Nickel Copper alloy. Yes, we spell the coin's name wrong.) Worked pretty well, on black powder and various other chemicals. Didn't try it on Aluminum.

[Edited on 11-3-2015 by Bert]

Microtek - 12-3-2015 at 02:01

I found high quality ceramic media on ebay. I recommend looking there, it was quite cheap (so cheap that I bought about 2.5 kg of it even though I had no actual use for it).

hyfalcon - 12-3-2015 at 04:20

Here's what I use In my ball mills:

http://www.ebay.com/itm/Alumina-GRINDING-MEDIA-BALLS-1-2-dia...

ecos - 12-3-2015 at 05:40

Ok , it would need some days to build it , Thx all for the info.


Just to understand the concept of AN as oxidizer , Nakka stated his formula as :

A24 : 68% AN , 4% S , 17% Al , 11% binder (Neoprene)



From the balanced equation , 68% of AN would need 15.2% Al.

if this is correct, this mean we have extra Al that still needs Oxygen, I think this would be provided from the binder ! , is my understanding correct?

but what about Sulfur ?

Bert - 12-3-2015 at 11:47

Aluminum is "oxidized" reasonably well by Sulfur- The Chlorine from the isoprene isn't exactly averse to combing with Al either.

PHILOU Zrealone - 12-3-2015 at 12:40

If the aluminium is activated...then in exces you would also have this equation with H2O overheated vapour:
2 Al + 3 H2O(g) --> Al2O3 + 3 H2(g) + heat

ecos - 12-3-2015 at 16:14

Quote: Originally posted by Bert  
Aluminum is "oxidized" reasonably well by Sulfur- The Chlorine from the isoprene isn't exactly averse to combing with Al either.


I think the reaction between Al and S would be like this :


this reaction would generate a lot of heat.

this mean :

  1. 68% AN would oxidize 15.2% Al
  2. 4% S would react with 2.2% Al


why don't we think that AN would oxidize S to get SO2 ?!

ecos - 12-3-2015 at 16:21

Quote: Originally posted by PHILOU Zrealone  
If the aluminium is activated...then in exces you would also have this equation with H2O overheated vapour:
2 Al + 3 H2O(g) --> Al2O3 + 3 H2(g) + heat


I was thinking about this but when I checked the equations :



I think this would need a lot of Al :) , I dont know if this is correct or not.

PHILOU Zrealone - 13-3-2015 at 05:37

Quote: Originally posted by ecos  
Quote: Originally posted by Bert  
Aluminum is "oxidized" reasonably well by Sulfur- The Chlorine from the isoprene isn't exactly averse to combing with Al either.


I think the reaction between Al and S would be like this :


this reaction would generate a lot of heat.

this mean :

  1. 68% AN would oxidize 15.2% Al
  2. 4% S would react with 2.2% Al


why don't we think that AN would oxidize S to get SO2 ?!

Welcome to the complexity of stoechiometrics and reaction products :D.

Of course S and an oxydiser will make SO2 and SO3.
But affinity of Al for O is greater than the affinity of S for O...
Electronegativity/electroposivity potential explain this.

So the reaction is possible but depends on the relative amount of each reactants...and may be statistically low!

Also heat of reaction will favour certain equilibriums and disfarvor others.

If you want 100% accurate reaction products this may involve a lot of maths, physico-chemical calculations.

Usually chemists remains on the general average reaction with major reaction products...yes we work with good aggrement approximations ;).
Most chemists are lazy :P

[Edited on 13-3-2015 by PHILOU Zrealone]

ecos - 13-3-2015 at 06:01

Wow :)
You shocked me !
So how do pyrotechnicians design the correct percentage? Is it trial and error process?

Bert - 13-3-2015 at 10:19

Quote: Originally posted by ecos  

So how do pyrotechnicians design the correct percentage? Is it trial and error process?


Stoichiometry and experience gets you into the ball park, then tests and adjustments to fine tune a device's performance. Optimum performance is often not found precisely at stoichiometric ratios...

Then repeat those tests and adjustments whenever you get a new batch of raw materials. Especially necessary when using natural products (charcoal, gums, resins, starches & etc.) or changing to a different supplier of oxidizers or metalic fuels. Seemingly small variations in composition of materials and particle size/shape can have unexpected consequences.


ecos - 14-3-2015 at 03:46

Quote: Originally posted by Bert  
Quote: Originally posted by ecos  

So how do pyrotechnicians design the correct percentage? Is it trial and error process?


Stoichiometry and experience gets you into the ball park, then tests and adjustments to fine tune a device's performance. Optimum performance is often not found precisely at stoichiometric ratios...

Then repeat those tests and adjustments whenever you get a new batch of raw materials. Especially necessary when using natural products (charcoal, gums, resins, starches & etc.) or changing to a different supplier of oxidizers or metalic fuels. Seemingly small variations in composition of materials and particle size/shape can have unexpected consequences.



My life became hard now :)

pfff , I need to read a lot to understand more.

regarding the binder , how would it decompose now ?

Neo has formula : [C4H5Cl ]n

This means it would be decomposed to H2O , CO2 and Cl . This mean we need extra oxygen to supply the binder ! would that make sense ?

PHILOU Zrealone - 14-3-2015 at 05:37

Neoprene will decompose into HCl or Cl2 depending on the amount of oxydizer.

And yes inert binder needs extra oxygen to burn what might be good to temper the reaction heat and speed.

Active binder contains oxygen to burn its own fuel and sometimes active binders are explosive/propellants on their own.

ecos - 15-3-2015 at 06:57

Quote: Originally posted by PHILOU Zrealone  
Neoprene will decompose into HCl or Cl2 depending on the amount of oxydizer.

And yes inert binder needs extra oxygen to burn what might be good to temper the reaction heat and speed.

Active binder contains oxygen to burn its own fuel and sometimes active binders are explosive/propellants on their own.


Great , That interests me a lot :)

Quote:

Polyvinyl acetate ---> Formula: (C4H6O2)n


I could find P.V acetate-based contact cement in hardware stores nearby, It has Oxygen rather than Cl. it also has H/C ratio higher than Neoprene.

but I think it doesn't have enough Oxygen !

ecos - 16-3-2015 at 06:38

I found this Page would be useful for others who deal with AN.

kecskesajt - 17-3-2015 at 09:14

Can I make a propellant using AN+Polystyrene?I know it is used in BLU - 82 with Al but that an explosive not a propellant.
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