ETN/binder as possible fuel

[HissingRDX]

I have been wondering about the possible use of ETN as a rocket propellant. It is like NG (nitroglycerin) as it is a nitric ester with similar characteristics, density, decomposition products etc., so I spent some time looking at NG as a rocket fuel. It looks like NG is not very good in terms of impulse compared to propellants like APCP, so given that. ETN has very low flame sensitivity in it's crystalline state, it melts and then deflagrates at a high temperature. Although I have found that ETN combined with a binder burns readily when exposed to a flame, I never tried burning more than half a gram at a time. The burn looks fairly energetic and given ETN's excess Oxygen balance, this can be used to oxidize the binder which can somewhat act as a fuel in a ETN/binder composition.

 

I know that an explosion would likely occur, and probably a high order detonation if it is tried in a rocket application because of the high pressure build-up and sensitivity of the compound, but if this is used as a grain in say a paper casing equal to a class C BP motor, would the potential specific impulse be at all better than BP?

[pyrojig]

This borderlines a HE discussion, as ETN has no place in pyro. It seems that the nature of the material stores poorly and is very sensitive to DDT. Putting it in a high pressure environment and your most likely going to get a cook-off , then high order cato. Yes though HMX and other materials are used for incredible rockets , the math and physics behind the scenes are way above my paygrade, and knowledge . My suggestion is use whistle , and stay the heck away from ETN as a propellant. It has better uses in the HE realm .

[HissingRDX]

I would conduct a test in an environment totally expecting and preparing for a high order detonation of all material.

 

I don't have HE permission here, but some HE's also have propellant uses. I think the performance of ETN would theoretically be similar to that of compounds like HMX because of identical decomposition products, similar densities etc. not to mention the fact that some of the binder can be oxidized by the additional O2 ETN decomposes to. I burned a sample of ETN/PIB. There was not black smoke or any carbon residue.

 

Also, what do you mean by cook-off?

Edited April 12, 2014 by HissingRDX

[FlaMtnBkr]

I would imagine he means there is enough heat and pressure to cause a detonation. That's my understanding of the term at least.

[hindsight]

Let see, so far in this thread we have mentioned nitroglycerin, erythritol tetranitrate, HMX (octogen), & RDX (active ingredient in C4).

I keep reading on APC that HE has no place in pyro.

Can you say "Cognitive Dissonance"?

[HissingRDX]

You might say that guns have no place in pyro, and yet blackpowder is discussed plenty.

 

 

This is not a matter of HE's unless we are talking about the detonation of these materials. Right now I mean their usage as propellants (Rocketry)

[leedrill]

well i have to agree this might be a question for propellents but when talking about this category of rocket propellents we are not talking about anything viable in terms of amateur rocketry

let alone the people that here understand the power of and respect needed for pyro the level for something such as ETN which draws the line for a primary is so much higher

this is not something you can try in a back yard considering the engineering needed for it and the danger of it

[Arthur]

The suitability of this idea for your use depends largely on your State's attitude to possession of HE! with a few failed trials you could have enough bangs and craters for the "men in boots" to come stomping round your house making life most awkward for you and your family.

 

"cooking off" is usually used to refer to propellants that explode when heated, causing local damage.

[hindsight]

You might say that guns have no place in pyro, and yet blackpowder is discussed plenty.

 

 

This is not a matter of HE's unless we are talking about the detonation of these materials. Right now I mean their usage as propellants (Rocketry)

Like all analogies, this is not a perfectly equivalent statement: High Explosives Devices are to High Explosives in pyro as Guns are to black powder in pyro.

[FlaMtnBkr]

There are high explosives in pyro?

[schroedinger]

Yep, sometimes e.g. picrates are getting used in whistels, but in most places there is no reason to use suchthings

[hindsight]

There are high explosives in pyro?

FlaMtnBkr-- Ha ha (love that dead pan humor). Thanks for the assist, since the point could have escaped some folks' attention.

 

schroedinger-- Keine Regel ohne Ausnahme.

[nater]

HPA prohibits HE at our club events. There have been people testing Tannerite type mixes as an option for bottom shots. It works, but I'd rather leave the HE out of pyro.

[FlaMtnBkr]

It has been many decades since picrates have been in whistle.

 

Hey, I have no problem with HE, and like a good boom just like the next guy. But they aren't routinely used in the art of pyrotechnics. Yeah, there might be some specialized uses where it could be applied. But most people don't want to press 2 g of ETN in a cap, much less a quarter pound in a 1# rocket.

 

AN in a bottom shot would be simple to pull off. However, it would be a make and shoot item. Even a cup of AN in 6 zip lock bags will become a soupy mess after a few months. And if you throw in a bunch of finely divided metal, there could be some other problems to think about.

 

If you think flash is nasty, it is a cute fuzzy kitten compared to high VoD HE and most primaries. This stuff really doesn't belong in pyro, and probably not even this forum although a casual discussion shouldn't be a problem.

[Arthur]

Well the solid booster for the shuttle flights was fuelled with an AP/Aluminium mix, which would normally be considered rather a lot of flash, but with the right construction it seems to work to give lift. HOWEVER those were designed above my pay grade so I'd be cautious doing a rebuild from the popular press words.

 

If you think you can do the job within your skill set and may do the job within your local law set then experiment carefully. Small size and distance become your friends when doing initial tests.

[FlaMtnBkr]

Would you agree that the space program is not pyrotechnics/ fireworks?

 

Sure, there are lots of crazy things used in the defunct shuttle program and military rockets, missles, and bombs where HE is a main component. But that isn't the purpose of this website. We make beautiful things to watch, not devices of destruction and death.

 

That said, experimenting is great. It results in thought and can lead to new techniques. If you can do something safely and it interests you, then go for it. Just make sure your set up is designed for an explosion and the worst case scenario. No one should lose appendages or eyesight just because a hot whistle rocket wasn't enough. Heck, high performance whistle rockets, and even BP, can take off so fast as to only get a glimpse for a fraction of a second. I personally don't need anything even that high performance to make some great firework rockets. But we also all have our own interests.

 

Rambling again. Time to put down the internet and slowly walk away for a while.

[nater]

Thanks to the HPR community composite AP propellents are not explosives of any type. I could see those types of propellents being used in a pyro rocket, if you wanted to go through the expense of the casings and nozzles or test if cardboard could contain the pressure. Those are still a bit different than the mixes proposed above.

[HissingRDX]

I suppose this is more of an artistic forum (which pyro is an art) and less a scientific forum. I will take this matter elsewhere.

[leedrill]

id say thats a good idea hissing i am actually one of the people on here with a shot firers licence allowing me to get to use such things but the fact is you will never get clearance to make something of this nature, legally anyway {which i think is obvious}

 

here we love the science and chemistry aspects of pyro

 

but the motors we make already are still making leaps and bounds forward in power that make, HE not a viable option for the laws and legaslation around them and the danger of them

 

the setup in factories for pressing det caps would mean for pressing a 3lb motor youd want half a ton of sand or more and a very very extravagant setup to make it safe in any way or form

 

you would not find anyone pressing that quantity of anything in that category not even petn in which case youd only be making small motors that will cost more than a 6lb whistle motor anyway

 

so the whole concept is just not viable

 

i understand your suggestion of using a binder composition with something of the sort HE but it is still just a plasticised HE with reduced sensitivity

 

but would still prove to be more expensive than just lifting 12" shell with 3x 6lb whistle motors and much harder to get any effect out of it other than adding TI blowing an arm off or vaporising the firing rack

[boule]

I know that an explosion would likely occur, and probably a high order detonation if it is tried in a rocket application because of the high pressure build-up and sensitivity of the compound, but if this is used as a grain in say a paper casing equal to a class C BP motor, would the potential specific impulse be at all better than BP?

 

You know, this is an interesting approach and has already been done by many different applications, although not in the pyro world. The only "HE" traditionally used was a 50/50 mix of picrate and KNO3 for whistling drivers (as already mentioned) and some amateurs boost their salutes. If you look behoynd the pyro world, though, HE has been used to a great extent in missiles. HMX, which is quite similar to your proposed ETN, found its use in the Trident II missiles and PETN is found in several military rocket fuels and sounding rockets. These HE fuels are usually melted and cast into place with a plasticizer and several other additives.

Now, the main limitation on pyro rocketry is not the fuel available but the pressure limits of the cardboard casings that are used for safety reasons. Any of our given fuels can be pused to pressures that will exceed the safety limits of cardboard and cause the motor to CATO. We get higher volume and mass flows from whistle than from BP and thus already have ample opportunity for lifting any payload and - if you consider effect propellants like blue strobe, red magnalium etc - also pretty much any darn effect we want.

 

Nonetheless, an HE-doped composite propellant might be of academic interest. Especially when considering composite fuels that require too much pressure to work properly with our motor constraints, those HE-fuels might come in handy. Take an APCP propellant, add a few percent of your favorite HE as burn rate modifier. It should give you more performance and might modify the pressure exponent of the fuel mixture sufficiently to be suitable for pyro use.

Will it detonate - I doubt since the HE portion of the fuel can withstand significantly higher pressures in ICBMs. Nonetheless a looong fuse would be in order.

Will it work - Don't know! Amateur rocketry should be able to make it work with significantly stronger motor casings than we are using but in cardboard? Even if you get it to work, if it will outperform established fuels is another question.

Will it catch on in pyro - Most likely not. Pyro is always a tradeoff between safety of the fuel itself as well as ithe maufacture of the motor, reliability of the motor, economics (since we throw away the motor after a single use), availability of the components and finally legality. Performance does facture in as well but since we can always use bigger or more motors.... Well, I don't think that HE-doped fuels will catch on fast in the pyro world. While they can probably be made safe and reliable enough, availability and cost will most likely be their downfall, not to say that most governments will not be very happy to see pyros handling HE.

 

Having said all that, there is a certain academic interst whether you can make such a rocket motor work. I'd suggest you start by researching the previously used plasticizers and devise your own fuel on this basis.

[pyrojig]

You might get more advise and experience from the SM forum. There are a few really great knowledgeable guys over there that share the same interest in the HE realm and rocketry. I would be leery about taking advise from some of the knewls that lurk there though. Look for the seasoned veterans, and ask them for pointers. As noted this forum is more of a art one, not one to dive into the use of HE as a "super fuel" research . Many of us love a good earth pounding boom , and even some of the HE studies . There are even a few of the members that blast for a living or obtain permits for such . It is a very interesting study as well as a unforgiving one for those who make that " one small mistake" that takes there life because they didnt plan for the unthinkable /.

[FlaMtnBkr]

Here is a thread about ETN that should be required reading for anyone that wants to experiment with it.

 

http://www.sciencemadness.org/talk/viewthread.php?tid=22554

[pyrojig]

Excellent point !!! Flamtnbkr

That really sums up the dangers of this EXP. Like I said, it only takes one thing to go slightly wrong , and If you didnt plan for it, it might end in a situation like that poor fellow. Playing with sensitive HE (primary capable EXP's) is just asking for a dangerous situation . Im sure under strict lab conditions and the right safety format ( bunker) one could create High energy fuels beyond the realm of amateur rocket fuels. But for Gods sake.......pick a diff. exp..... one that is more stable and a secondary w/o primary tendencies .

[markx]

Even the bare idea of having to handle the better part of say a 10g amount of plastified ETN in a rocket motor casing is just scary to say the least. Please stay away from that type of ventures....it is courting disaster by definition. The power from such substances (nitric esters) is enormous and an accident will have permanent consequences. Even sub gram amounts of these substances have the potential to gravely injure the unfortunate experimenter if something goes wrong. The most powerful FP is humble in comparison to even mediocre HE-s and ETN is by far not mediocre.....it is just a totally different playground that should be reserved for professionals with proper experience and the means to take precautions.

[leedrill]

very well put markx couldn't agree more