Smokeless powder as fuel?

I was making some nitrocellulous a long time ago and, just for fun, dumped some really thick gell into a short tube (spent motor casing). I let it sit
for a few days (actually, I forgot about it). I later lit it and it seemed to do fairly well for the small amount that I put in there.
I haven't tried that again - yet.... I really don't want to make a big boom, but I'm wondering if it is worth trying to make a rocket motor with this stuff. Anybody every done this before?
Pete
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Some military rockets, such as air-to-air missiles, use "double base" propellant, which is a mixture of Nitrocellulose and Nitroglycerin. It tends to burn quite fast, generates high thrust, and is obviously smokeless. Clearly, due to its composition and excessive thrust characteristics, it is pretty much outside the realm of the amateur.
Most amateurs want to be able to follow and track their rockets, so a smoke trail is desired. Even when it is not desired, it is possible to tailor one's propellant formula accordingly. Additionally, the burn characteristics of APCP are better than those of DB in terms of applicability to amateur rocketry. I don't have my copy of Sutton on hand, so I can't give you a formal comparison of the propellants' properties.
DB is also capable of making a deflagration-detonation transition, an obviously unsafe condition from which common APCP motors do not suffer. As such, it is classified as a 1.1 high explosive, whereas APCP is usually 1.3 or 1.4, depending on the size.
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That's very interesting.

... and that is exactly what I was concerned about...
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NC/double base compositions have many drawbacks where rockets are concerned
The burning rate is sensitive to pressure and temperature. The pressure sensitivity makes it hard to create a reliable rocket from it. It can be done, but it ain't easy.
The process of making the stuff is hazardous. Runaway, nitration causing copious NO2 evolution and possible explosion, is not unusual. Of course, you can buy it, but solvent casting is not easy in any case.
If not stabilized, it deteriorates over time - in a autocatalytic way, so that if it is confined, it eventually explodes.
It can detonate
It's not as powerful as AP composites.
It's more expensive than AP composites
It has one advantage: The idiot US government is less concerned about it than it seems to be about AP. Go figger.

sit
seemed
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Yet they use it for air-air missiles and military munitions that require some level of insensitivity(reasonable for a ship or vehicle under attack;can't have the munitions explode when a enemy charge goes off nearby.) They also have to have a Mil-Spec wide temperature tolerance,so they can be used in widely varying battle field conditions.
They have some reasonable shelf-life,for the military to buy missiles and munitions in large quantities.Certainly better than APCP in our MR motors,that swell and crust over and become hard to ignite.

Because it's advantages outweigh the disadvantages for their purposes. (obviously)
From Brian McDermott's post;
Some military rockets, such as air-to-air missiles, use "double base" propellant, which is a mixture of Nitrocellulose and Nitroglycerin. It tends to burn quite fast, generates high thrust, and is obviously smokeless. Clearly, due to its composition and excessive thrust characteristics, it is pretty much outside the realm of the amateur.
"generates high thrust",and "smokeless,harder to track",they also have to have a Mil-Spec wide temperature tolerance,so they can be used in widely varying battle field conditions. ;that's -Three- advantages.
--
Jim Yanik
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be
Your post has given me more interest. However, as an amateur, I'm thinking I cannot do the quality control that would be necessary for this type of motor and it is very possible that my manufacturing process would most likely result in a certain percentage of explosions - which is rather unacceptable.
On the other hand, the availability of such a product is quite tempting and may become an interesting study to improve my methods.
I read in another post that solvent casting is not easy. I can see how that would be true and could result in detonation due to the uneaven evaporation of solvent leaving burn and pressure points, but perhaps this could be worked out.
While I was first opposed to the thought of another poster's suggestion of "grinding" a mass of solidified smokeless, I may rethink on that subject. But I don't think I want to put this stuff in with BP. However, BP may not be a bad choice to get it up to speed for a first stage.
As for smoke tracking... I consider that an easy fix with other components involved near burnout.
Anyway... I'll probably do a little work with this while keeping all the warnings in mind.
Pete
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If you mix 10% smokeless by weight with a stable black powder substitute called "American Pioneer" grinding is not risky. In fact American Pioneer recommends grinding their FFFG powder into a fine dust to make flash powder for flint lock rifles. Do as I suggested. Dissolve the smokeless in acetone. Then mix the ground American Pioneer black powder substitute (finely ground) with the dissolved solution and keep mixing and kneading until it dries out and becomes a powder again... Then grind it again to break up any granularity left in it. At that point you can tamp it into a motor just as you would BP. It is quite consistent. You can get American Pioneer FFFG at a local gun store that sells Black Powder guns. Or, You can order it on the internet from Midway.com or Cabelas.com etc. Or just do a search for American Pioneer Black Powder.
KT
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----- Original Message -----
Newsgroups: rec.models.rockets Sent: Saturday, July 30, 2005 10:16 AM Subject: Re: Smokeless powder as fuel?

be
The comment to which you are responding is about shelf life, and not about shock sensitivity.
NC breaks down over time, liberating NO2, which makes the decomposition happen faster still. Military propellants and smokeless powders contain stabilizers like diphenylamine and ethyl centralite, which react with the liberated NO2. They inhibit the acceleration, but not the original decomposition. This sort of thing is not a problem with AP composites, and AP propellants are, as a matter of fact, far more storable than single or double base compositions. You can (and many here do) use AP grains stored for ten years swelled or not. Wouldn't try that with an NC composition.
As for the reason the ATF worries less about smokeless powder than about AP, it's because smokeless powders are gun-related. Guns are mentioned in the US constitution, and AP is not. As a matter of fact, the military uses NC/NG compositions much less in rockets, now that AP compositions are available.
I have actually seen photographs of foreign NC-based model rocket propellant slugs. They do exist. They are, however, well beyond the capability of the amateur to make. Solvent casting and extrusion molding requires a remarkable capital investment.
The pressure exponent of NC compositions is on the order of 0.7 to 0.8 as opposed to 0.1 - 0.4 for AP. That means that linear burning rate, for NC, goes up with the third to fifth power of the burning surface, when throat area is held constant. (For AP, it goes up with the 1.1 - 1.7 power of burning surface.) This property makes motor performance sensitive to nozzle fouling and erosion. This is why it is much harder to make a rocket from NC compositions than it is to make one from AP.
Temperature sensitivity of NC is so great that the army has made electric blankets for some of its missiles, because they don't work right in cold weather.
I haven't commented much on double base (with nitroglycerine) compositions. Powder companies hire older, retired people to wheel the NG carts around and add the stuff to the mix. The carts are called "Angel Buggies". Now and then there is an accident. Oh well.
At the end of the day, the properties of the stuff are what they are. It matters little what I or anyone else says. I recommend you leave the stuff alone because IMHO, it has many disadvantages, and because using the stuff in that way is illegal. That's all I can do. Maybe I'm wrong. What do I know?
Luck and Regards, -Larry Curcio

be
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surface,
Sorry. I meant to say that equilibrium chamber pressure has this relationship with burning surface area at constant nozzle throat dimensions. I mistakenly mentioned linear burning rate instead.
Regrets and Regards -Larry Curcio
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Great post.
This should be in the FAQ.
--
Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
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I have made my own BP end burner motors. I can duplicate size and thrust for Estes motors without a problem. For Grins I experimented mixing smokless shotgun powder with it. I figured if I just used a little smokeless with the BP It would not get out of control. I was right. Although my thrust dropped slightly but not significantly. Tried adding more and got an explosion. But with the right amount of smokeless powder one can make a beautiful end burner. I say beautiful because usually Estes size BP end burners all you see is the smoke, no flame. However by mixing the smokeless with the BP there is significantly more flame. You still get the smoke but the flame becomes visible, similar to core burners. What I did was mix no more than 10% by weight of smokeless with the black powder.
The problem is getting the grains of smokeless fine enough to mix with the BP. I found that if I mixed the smokeless with a significant amount of acetone (enough to cover the smokeless by 3 times or so) to some what dissolve it then while it was still liquid I mixed the BP with it the mixture becomes a thick gooey mixture. Keep mixing it as the acetone evaporates it becomes like bread dough. start kneading it by hand. as it dries more it begins to crumble up. keep mixing using the back of a spoon pressing it and kneading it until you have a powder, some what granular powder however. Then grind it up to a fine dust with any method as you wish. I use a large rectangular sharpening stone and an Iron pancake griddle for grinding in small quantities. Once it is a fine powder you are ready to cast your propellant just as you would any BP propellant. But you don't need a binder because the smokeless powder acts as the binder with acetone being the solvent. Actually I don't even use acetone as a solvent I just put the powder in dry and press it in with a tamp and press/drill press. Sticks together good dry.
As always do this at your own risk. I take no responsibility for any stupidity on your part.
KT
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wrote:

dumped
with
Estes
get
are
you
Hmmm... I never use a binder in my bp rockets anyway... Tends to clog the nozzle.
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I don't either. But I know some people do use a binder in their BP propellant.
KT
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Hmm, I'm a pretty experienced handloader and all of this raises a few questions: 1. Which smokeless? They all have very different burning and pressure curves. For example, Bullseye is very fast and pressure builds up to dangerous levels with very small amounts.....we are talking in .10 grn by weight. AA 5744 is much slower and variations of 1-4 grns. will not change things much. 2. Some Smokeless powders have a nasty reputation for detonation if conditions are not exactly right. How can one control that in a model rocket? 3. Smokeless is very expensive. Do the benefits offset the excessive price? 4. The burning rate of smokeless is determined to some extent by grain shape/size and coating. If you alter this, what means will you use to control detonation?
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R. J. Talley
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1. IMR 4895 2. 10% by wt IMR 4895 dissolved in acetone and mixed with 90% BP won't detonate... At least I have not had that experience. 3. Probly not.... but it's something to do. It's also a lot of work and does not increase thrust but actually reduces it a bit.. But burns with more visual flame. 4. when you cover the IMR with 2 teaspoons of Acetone and stir the grains desolve into a gummy goop at which point you mix in the BP and keep mixing and kneading until the acetone evaporates and the mixure breaks up into a fine grainy powder. Then after it is completely dry you grind it up into a fine grainless powder. There is no grain or coating. At that point you tamp it into a case as you would BP. Again I have had no problem with detonation if I keep the smokeless at or under 10% by weight.
kt
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On 6-Aug-2005, snipped-for-privacy@pacbell.net wrote:

Oh I forgot...
Use this in end burners only. It burns to fast for core motors (That is if you use true black fffg powder or a substitute as it comes from the gun store). But obviously you would have to grind up the BP first. Using it in the FFFG grainular configuration will only blow up the motor. After grinding up the BP into a fine powder then mixing it with the acetone IMR mixture.
kt
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