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Author: Subject: Fuel-Air Explosives
grndpndr
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[*] posted on 9-3-2009 at 05:26


All due respect 497 but those who have survived dust explosions havent called them whimpy.Nor would the results of a dust explosion where reinforced concrete grain handling facilitys have been reduced to rubble could be called insignificant.

Granted where not talking the power of an engineered FAE
but a great deal of death and destruction have been caused by dust explosions.Generally accepted as fact now is that mysterious old coal fired luxury liner sinkings have been destroyed by coal bunker dust explosions.
1in thick hulls split open again isnt insignificant.

While Ill say again engineered FAEs contain a great deal of power to dismiss out of hand the not insubstantial power of a dust explosion seems out of character 497 particularly IF the literature hasnt been read.It seems akin to saying gas leaks in buildings produce insignificant power.That may be true compared to a military multi million $ engineered devices but the occupants are still dead and the building and immediate surroundings destroyed.

Im well aware this site is largely theoretical and thats well and good and in fact quite interesting.But so are the ideas/materials that are within the ability of the average experimenter to obtain and fabricate and finally the power contained in the dusts when the requirements for detonation are met is far from insubstantial, 200mph plus explosion/deflagration fronts, 90psi shockwaves lasting .045 sec insubstantial? I believe 1/2 the shockwave value alone will kill a human being w/90psi shockwaves destroying all but underground purpose designed bunkers.However as far as a dust explosion is concerned atomized metals do seem to meet the severe explosion rating for dusts while coal and
grain dusts less so.If cost is a concern!?

Dust is very likely the grandaddy of the FAE Idea.

[Edited on 9-3-2009 by grndpndr]
Edited ad infinitum correcting figures, toning down tenor of post.

[Edited on 9-3-2009 by grndpndr]

[Edited on 10-3-2009 by grndpndr]
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[*] posted on 13-3-2009 at 00:07


It's amazing what things will do when confined...

Yes, I agree dust explosions can certainly do damage, quite a lot, for sure. But personally I'm not terribly interested in things that require containment... Far harder to experiment with, and much less versatile..

Quote:

200mph plus explosion/deflagration fronts, 90psi shockwaves lasting .045 sec insubstantial?


Depends on what you compare it to... Compared to 4000mph and thousands of psi, yes, I still say it is insubstantial.. For a deflagration/dust explosion to do you any harm, you basically have to be in it.

There's nothing hard about demolishing a building, if that's all you need to do. A propane tank and an igniter are all it takes, no mystery about it.
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[*] posted on 13-3-2009 at 00:38


Have any of you looked through US4463680, "Method of generating single-event, unconfined fuel-air detonation"?

It details using diesel fuel in a non-sophisticated FAE design with a single central HE dispersing charge, and no delayed second ignition charge. The novel aspect of the invention is to use ferrocene or one of a few other compounds as a catalyst (2-10 % based on the amount of fuel). The catalyst is either dissolved in the fuel, or arranged in an annulus between the bursting charge and the fuel.

They also talk about making proof-of-concept tests in the lab with sub-ml quantities (apparently using pneumatics instead of HEs to disperse the fuel). Anybody know of a good source for ferrocene?
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[*] posted on 13-3-2009 at 10:51


One could use a coffee-mill with a built-in spark-plug to test for dust-explosions: The mill will create a fine dust within it, out of every sort of powder, eg. charcoal ... (as confinement maybe a thin one-way plastique-drinking-cup instead of the usual lid, much less dangerous and lets the energy away, so the coffe-mill is preserved; anyhow: Do from safe distance, since the quickly moving mechanical parts of the mill are dangerous enough)

Besides this could have a technical use someday: Diesel originally wanted to invent a engine running on coal-dust, not oil ..., but the use of otherwise useless heavy-oil worked out just brilliantly ...

If coal-dust or any other stuff could be utilized for running a car: This would be very great, since many such substances grow on the fields of any country, and do not have to be ordered from the Saudis ...

And what about the following ignition method: Abusing a magnetron, powering it by capacitor-discharge ..., for a multi-kW pulse, creating ignition with a 3D-distribution ... (hereby not patentable any more !)

[Edited on 13-3-2009 by chief]
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[*] posted on 13-3-2009 at 12:22


@Microtech. Yes, I've seen that patent. All the catalysts are too exotic/expensive for my liking.. Also I'm skeptical it works as well as they say, from what I've seen in a few papers about single event/catalyzed FAEs the results were marginal. But it would be so easy to test.. Get your ferrocene here.

Personally, I don't think a two event type FAE would be that hard to pull off. A friend of mine is close.

@chief. Burning coal dust in engines has been investigated very thoroughly. It doesn't work, they get fouled by the ash too quickly.
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[*] posted on 13-3-2009 at 12:50


@497: Maybe then sugar could be used: It gives no ash, and can be simply crystallized to that purity ...

Also: On the world there can be produced any amount of sugar, it's only kept expensive by cartels ; in reality , by the production-cost, it is very cheap ..., and renewable. Crystal-sugar contains only C, H and O, so no ash ...
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[*] posted on 13-3-2009 at 17:44


You could cover the world with sugar plantations and there still wouldn't be enough to begin to fuel the worlds vehicles...

It might not make much ash, but it might be hard to get sugar to burn anywhere near cleanly... Also it is not known for it's fast burning characteristics. It would have to be some VERY fine powder, and even then I doubt you would be able to get a whole lot of power out of it in an internal combustion engine..
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[*] posted on 13-3-2009 at 23:38


Just this evening a documentary about renewables and alcohol revealed it required nearly the same amount of fossil fuel to produce an equivalent amount of alcohol.
I would expect farming sugar cane/beets would be equally as expensive in terms of resources.Personally think corn or any foodstuff used to produce fuel is a very poor way to goAs well the resulting ash from direct injection of coal dust in a traditional piston engine would make for a very short lived powerplant as was pointed out.Perhaps some other design to take advantage of the overpressure /wind speed.
Turbine of some type, with a precombustion chamber?Coal fired anything is a very dirty device so a mechanism for pollution control just might make such an engine size impractical?

As far as FAEs 497 I guess it depends on ones intentions for his device.iirc figures like that rival the effects of nuclear devices at varying distances, I for one would avoid exposure to anything approaching 90psi overpressure and 200mph windspeeds.An individual needent be IN the explosion to be killed by the overpressure or windspeed of the dust explosion. respectfully:)

[Edited on 14-3-2009 by grndpndr]

[Edited on 14-3-2009 by grndpndr]
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[*] posted on 14-3-2009 at 00:20


^ I totally agree with the first paragraph. If one was intent on burning coal to push their fat ass around, I would suggest an external combustion engine such as a Stirling cycle.. The burner might crap up fast, but at least the engine would stay clean.

Quote:
I guess it depends on ones intentions for his device.


That sums it all up well... And yes the gov't has thought about (maybe gone through with?) using FAEs to simulate small nuclear detonations..
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[*] posted on 14-3-2009 at 15:05


The world _can_ produce way more than it does -- as seen from the EU: Everything agricultural is regulated in such a way as to produce little enough so the prices stay up. Farmers even get government-money in order to do nothing;
of course distilling the alcohol out of anything consumes much energy ...

But sugar can burn quickly, as those sugar+chlorate recipes show ...

Never listen to the oil-is-best- propaganda: It comes from the same people who made oil-prices quite high last year ... ; now they are only down to prevent investments into other energies ... can't let them up for too long .... ; but they are gonna milk out the optimum amount of money out of everybody also in the future ...
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[*] posted on 16-3-2009 at 05:00


Im geting dangerously far afield and yes I am disturbed by ranchers/farmers the largest entitlement group I am aware of driving new 1ton duallys to town for grocerys.But factually land must rest.ergo paid for planting nothing or preventing overgrazing which is extremely devestating denuding mainly national grassland thats been leased not owned by the ranchers yet treated as personal property when it comes to hunting etc on our land.Sorry for the rant.

Dust explosions rock! Ask the dead.:(
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[*] posted on 17-3-2009 at 14:25


Back to FAEs particularly dust explosions I was curios as to whats needed to destroy a house from overpressure alone.

Apparently a stick built home suffering overpressure of 7-14
KPA will be completely destroyed.A concrete wall built of co unreinforced concrete block 30cm
thick or cast unreinforced wall will be destroyed by 10.35-38
KPA exterior overpressure.The figures were borrowed from nuclear blast effects,FAEs obviously far less lethAL less the radiation and effects of intense light/burns the effects of overpressure remain the same not inconsequential and possibly not needing confinement.

Appreciate the patent Microtek have to check it.A single event
FAE particularly if a inexpensive dust or fuel and catalyst can be used it would be quite useful.All respect an indoor dust explosion strategically placed and timed...

[Edited on 17-3-2009 by grndpndr]

[Edited on 17-3-2009 by grndpndr]
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[*] posted on 17-3-2009 at 16:57


Buildings, expesially houses, require *very little* overpressure from the inside to flaten them. Those numbers look high to me. More reasonable for outside overpressure, but there is a big difference. I seem to remember seeing that less than 1 psi of internal overpressure is required to destroy stick buildings, and around 3-5 for concrete buildings IIRC. The numbers are around, maybe in a patent, I can't remember exactly.

There is no need to worry about attempting a single event catalyzed FAE for a contained dust type explosion. The only point of using a catalyst is to replace the precisely timed initiator charge required to get a full detonation out of a true FAE. With a dust explosion, there is no detonation, thus no need for a high explosive initiator. Any decent flame, flash powder, thermite, etc, would work to ignite a dust explosion. It could probably be made to be a single event setup if one added Al or Ti powder to the high explosive burster (if there is one).
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[*] posted on 17-3-2009 at 19:57


Thanks again 497.In fact the figures were indeed for external pressures.I apparently was to vague in my explanation.Thanks again all advice /input is greatly appreciated.I had however some interest in a actual fuel air explosion rather than a simple dust explosion.As we agree a dust explosion has its time and place when conditions are right and I cant think of a less expensive way to demolish a home etc.We do have abandoned homes from farmstead days but that may be overly ambitious lol really!!
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[*] posted on 18-3-2009 at 00:16


I often wonder what an entire building filled with stoiciometric oxygen-acetylene would look like going off...

Anyway, here's my rough draft of a plan for a *real* FAE (which has never been documented in the amateur community to my knowledge):

-Fuel: Diesel Cetane Improver. Depending on the brand, some contain 20-35% octyl nitrate (ethylhexyl nitrate actually) with the balance being mostly naptha, etc. This would make an ideal fuel when used straight out of the bottle.. The octyl nitrate could possibly be concentrated by boiling off the light petroleum products to increase its concentration up to 40-60%, but I doubt you'd need to do that. Alternatively, if you were extra hardcore, you could synthesize your own ethylene/propylene/butylene oxide.. About two liters of fuel needed regardless of what type.

-Fuel container: Two liter PETE soda bottle. Ideally it would be raised off the ground a few feet.

-Bursting charge: 5-20g ETN or equivalent electrically initiated with primary of your choice. Exact sizing of the bursting charge seems to be relatively unimportant..

-Initiator charge: 100-300g ETN or equivalent (the more brisant the better) electrically initiated with primary of your choice. Hard to say the minimum amount without testing. Initiator charge should be placed about 4-6 feet away from the fuel container, and on the same horizontal plane.

-Electronics: Remote fireworks display unit found on eBay, etc. Long range remote control. Can be easily programed to fire one charge (burster) and then the other (initiator) 100 milliseconds later. This is a good timing delay. I know how these work because a friend has one.

Hope that helps a little.. If I'm lucky I'll get to watch a similar setup in action soon.

Keep in mind the overpressure delivered at a distance could be equivalent to somewhere between 4 and 0.5 kilograms of TNT, depending on the fuel and conditions.

PS. I just found the attached file. Have fun.

[Edited on 17-3-2009 by 497]

Attachment: solid fuel FAEs.pdf (593kB)
This file has been downloaded 1021 times

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[*] posted on 18-3-2009 at 04:26


Years ago when i worked seismograph I had electronic delay detonators of various delays,shame they were essentially wasted.
as in reqular nondelay caps.I would want to be a substantial distance from the oxy acetylene explosion filled a few balloons while oxy
acetylene welding a few times cant imagine an entire home filled with a correct mix!Heck a guy could put plastic over the broke out windows use a little caulk and foam little ciphering for mixture and...
doubt a fire truck could be summoned in time or even the fire /explosion discovered until smoke rising in the horizon.
Not a good style if one wanted to keep his hobbys private even though it would be some time before the Unfortunate "lightning strike" discovered.;)
Appreciate the file 497

[Edited on 18-3-2009 by grndpndr]
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[*] posted on 18-3-2009 at 07:18


I don't think there would be anything very solid left for the fire department to put out. :P

I thing I'm safe, considering I don't have the means to test a design like that now or any time soon. People publish far more "dangerous" ideas/designs all the time over at RS with no repercussions. It's not anything extremely original, just an adaptation of designs that our own military and patent service have published.

[Edited on 18-3-2009 by 497]
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[*] posted on 18-3-2009 at 10:28


Me either its just a fun topic of discussion that just happen to enjoy.To actually commit such an act is so far from my comfort zone or need for kicks the very idea is laughable but the actual disussion god help me I do enjoy.

A middle age adolescent in that respect.Could be worse,I could be the local deputy who patrols our small town a few hours a week under arrest for essentially being a sexual predator against the civilians he was sworn to serve and protect but charged with 3 counts of rape ,.1of giving false info to states CID.:o
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[*] posted on 18-3-2009 at 10:44


Those 300 g of ignition-charge are quite much -- it's not a clean fuel-air-explosive then, but a 300g-charge -fuel-air- explosive ... ; what about more smaller charges, instead of the big one: Would it still work ?

A wire-frame with a lot of electrical sparking-points might provide the ignition, maybe 1 spark each cubic foot ... ; but would the effect be the same ?
Maybe the principle is different: The fuel is not the explosive, but only provides a atmosphere within which the HE-pressure-wave can travel with less decay ... ... because of the potential energy of the fuel ...

The fuel-atmosphere reduces the necessary compression work for the "ignition"-charge, since it's capable of self-compression ; thereby the ignition-charge gets more range ...

Maybe the fuel alone couldn't do it (?) even if it would be ignited at numerous points at the same time ?

I just hope that everyone here knows the Feynman-physicsbook-explaination about shockwaves (in the 1st of the 3 thick books)

[Edited on 18-3-2009 by chief]
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[*] posted on 18-3-2009 at 10:52


If my above theory would be wrong and the fuel _could_ undergo detonation even from ignition by numerous mini-sparks:

Then shaped charges could be made, abusing the possibilities of 3D-arrangement of the sparks ; maybe 3D-microwave-ignition would be possible as well (with some fuel-components that give easy plasma) ...

this then could give quite some sort of rocket-engine ... !
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[*] posted on 18-3-2009 at 14:56


From that article on solid fuel FAEs, flake aluminum seems to be a very effective fuel. I wonder then, since a 1:1 magnalium alloy is so brittle, how about packing a brisant HE inside a magnalium cylinder? Maybe the detonation would produce (and disperse) magnalium particles of a sufficiently small particle size that it would be useable for FAE purposes...
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[*] posted on 18-3-2009 at 15:24


Quote:

Those 300 g of ignition-charge are quite much


Yes 300g would be more than enough, for sure. But it all depends on how sensitive your fuel is, and how reliable you want the device to be. When the military was testing propylene oxide detonation in old quarys they used a spherical 1/2 pound C4 charge IIRC, even though propylene oxide is a very sensitive fuel. If I was going to try it, I'd start with a charge around 100g and if it worked, then maybe try smaller ones, if it didn't then I'd try increasing it's size.

Using sparks, flames, etc, is a good way to get a pathetic deflagration out of a perfectly good FAE cloud.. Not saying it would never work, but it would be a hell of a lot harder to get working, compared to synthesizing a few hundred grams of HE. As I understand it, the powerful shockwave from the FAE passes through the cloud virtually instantly (compared to most things) and basically forces the entire cloud to ignite at the same time, which is what allows the powerful detonation. When only a parts of the cloud are ignited (eg, by sparks) the flame front travels through the cloud relatively slowly and results in a deflagration of weak detonation at best. And that 100g of ETN would be minor compared to the main shockwave that followed behind it.
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[*] posted on 26-3-2009 at 22:57


Quote: Originally posted by Microtek  
From that article on solid fuel FAEs, flake aluminum seems to be a very effective fuel. I wonder then, since a 1:1 magnalium alloy is so brittle, how about packing a brisant HE inside a magnalium cylinder? Maybe the detonation would produce (and disperse) magnaluminum particles of a sufficiently small particle size that it would be useable for FAE purposes...

Using the magnalianium alloy as a container the resulting detonation/blinding fireball ignitingtoDDT the fuelSuch as a flake AL.How about titanium /al alloy?supposed long lived ignition source? surround over the device suspended off the ground.I dont recall that the article advised containment was a leg of the detonation of AL flake?I wonder if an actual container would be needed made from the magnaluminum or simply a plastic bag one with the magnaliminum surrounding the HE and another surrounding the magnaluminum fine mesh flaked AL?Unless contemplating a projectile of course

iirc magnesium is not an inexpensive metal so experiments w/o mag.would be in order,same with titanium.

Flake AL-Pottassium perchlorate! that should accomplish some type of dust explosion? found in the FAE article just a quick mention never the less even if used like the black book
inspired dust explosive I would expect some extreme fireballs at minimum hopefully detonation out of doors.Ratios would be needed but a very small scale experiment now with snow on the ground would be safe.And IIRC theres a small concrete guard shack on National grassland.To bad no balls no blue chips.:( by the wat besides the small guard shack theres hundreds of concrete munitions igloos complete with several ton doors intact about tyhe size of a tennis court some 13-14 miles from town. Outside locking of multiton door the trest of the bunker covered with afew feet of earth.Until a cleanup in the late 90s shells from 20mm-155mm pluis would wash out of the hillside regularly.By regs they were supposedly burned to deflagration or detonation but not carefully.Just as in riussian areas of intense ww2 combat they still unearth projectiles use a double boiler and salvage the military he filling from the projectiles selling it on the black mkt.Please excuse the excessive edits!
[Edited on 27-3-2009 by grndpndr]

[Edited on 27-3-2009 by grndpndr]

[Edited on 27-3-2009 by grndpndr]

[Edited on 27-3-2009 by grndpndr]
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[*] posted on 27-3-2009 at 09:05


Quote:

I wonder then, since a 1:1 magnalium alloy is so brittle, how about packing a brisant HE inside a magnalium cylinder? Maybe the detonation would produce (and disperse) magnalium particles of a sufficiently small particle size that it would be useable for FAE purposes...


I am doubtful that it would produce fragments small enough to burn effeciently. I could be wrong though.. It would be easy enough to try..

On a somewhat similar note, I know it is possible to get a lovely thermobaric effect by detonating cylinders of laminated layers of [plasticized RDX sheet -- teflon tape -- aluminum foil]. That's the warhead the "Hellfire" missiles contain, apparently it works well. Not quite an FAE though.. Still, it shows that it is possible to use metals in forms other than powder.. I'll post the patent if anyone wants..
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[*] posted on 27-3-2009 at 13:20


Quote: Originally posted by 497  
Quote:

I wonder then, since a 1:1 magnalium alloy is so brittle, how about packing a brisant HE inside a magnalium cylinder? Maybe the detonation would produce (and disperse) magnalium particles of a sufficiently small particle size that it would be useable for FAE purposes...


I am doubtful that it would produce fragments small enough to burn effeciently. I could be wrong though.. It would be easy enough to try..

On a somewhat similar note, I know it is possible to get a lovely thermobaric effect by detonating cylinders of laminated layers of [plasticized RDX sheet -- teflon tape -- aluminum foil]. That's the warhead the "Hellfire" missiles contain, apparently it works well. Not quite an FAE though.. Still, it shows that it is possible to use metals in forms other than powder.. I'll post the patent if anyone wants..


Please! post the patent! i am most interested in tyhe effect of the easily available teflon tape or other forms in addition to the flake AL.Whats your take on the AL flake and pott perchlorate as a dust explosive as per the file above?
(solid fuel FAEs.PDF 593kb)Very interested in any patents /files
with teflon/al as the fuel perhaps including ratios etc.mainly an excess of teflon or aluminum degrade/negate any effects.
My hope is for a single event FAE with an actual high order detonation preferably in as varyed a weather as possible,unconfined of course. thanks.I ws under the assumption the hellfire used mainly CSCs sophisticated tandem warheads possibly but wasnt aware of what would the teflon/al/essentially detaflex warhead be called?enhanced blast?I would assume its targets to not be hard targets like armor, perhaps buildings,bunkers soft vehicles.

[Edited on 27-3-2009 by grndpndr]

[Edited on 27-3-2009 by grndpndr]
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