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nitro-genes
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I don't think detonating IPA itself will produce any effect at all. TNT isn't a thermobaric explosive despite of its negative oxygenbalance as well.
There is an orange fireball from oxygen-poor explosives though it doesn't add to the blast energy like metal powders do. Most of the carbon after a
TNT or semtex detonation is visible as blacksmoke consisting of unreacted sooth that hasn't reacted with the surrounding air.
Metal powders can somehow burn much better under the oxygen poor conditions after the detonation, possibly because the reaction of aluminium with
oxygen doesn't produce an expanding gas like carbon does, diluting the heat produced. For this reason I was quite surprised to see a reactive surround
EBX consisting of an carbon based surround, I'm curious which additives they used to pull that off. 
AN + Al mixtures can defenitely produce thermobaric effects, the only difference beeing the amount of aluminium that can be added to be still
detonable. In that way are aluminized PBX compositions much more energy dense.
IIRC, depending on the mesh size of the aluminium only 3-5% of the aluminium reacts directly in the reaction zone that is followed by the shockwave
itself. This is why Ammonal compositions are more sensitive than AN itself, and about 3-5% gives the most sensitive mixture. Larger percentages added
behave inert and produce the elongated pressures characteristic for thermobaric devices hence react after the initial detonation. The secondary
combustion cloud can be seen very well in videoclips that were shot at night of booster initiated 80% AN + 20% Al charges. The shockwave felt very
"thick", and much more pronounced then from ANNM or ANFO charges of the same weight.
[Edited on by nitro-genes]
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quicksilver
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| Quote: | Originally posted by Mardec
And the Al, which mesh should it be? Using precious german blackhead just isn't going to happen..
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I have actually seen mil-surplus Al in various grades and the material used for energetic materials. Clearly written on the packing was "400 mesh or
finer w/ .05% ALB" (I don't know what ALB meant, however).
It was flake but appeared to be a less reflective material and did not have such a "greasy" feel like 325 mesh w/ stearic acid.
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Mardec
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| Quote: | Originally posted by quicksilver
| Quote: | Originally posted by Mardec
And the Al, which mesh should it be? Using precious german blackhead just isn't going to happen..
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I have actually seen mil-surplus Al in various grades and the material used for energetic materials. Clearly written on the packing was "400 mesh or
finer w/ .05% ALB" (I don't know what ALB meant, however).
It was flake but appeared to be a less reflective material and did not have such a "greasy" feel like 325 mesh w/ stearic acid.
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Google is saying all sorts of crazy shit, that AlB = Aluminium boride. AlBx
X being a variable..
AlB is used as coating for metals..
But anyway, I have some 400 mesh Al in my lab, with stearic acid on it. Will get that shit of off my Al and then after exams do some testing
[Edited on 2-6-2007 by Mardec]
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E-tech
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There are no single-component thermobaric explosives, they are all mixes using Al, or fuels surrounding the charge. The isopropyl nitrate is used as
an energetic binder to insure that all the aluminum fuel is consumed; It won't do much on it's own as far as thermobaric effects are concerned.
In other news- the Russians have another thermobaric mix that does use AN. It also includes Al and isopropyl nitrate, but the exact mix is not known.
Military Parade Publishing (a Russian arms catalog they print) has pics of what is sold as a thermobaric submunition; it is said to hold 22 pounds
of the mix. It looks like they are forgoing the weight/volume efficiency of explosives like HMX in order to obtain better far-field effects. The
submunition looks like a coffee can on a parachute- still wouldn't like to get caught in a field of them, though.
I've worked with small (100gram) charges of RDX explosives with a thermite surround, and found the effects to be noticably different; materials pushed
farther away and scorched whereas the no surround charge barely moved the objects around it. I haven't had a chance to test the really noticable (by
the US military) effect of the thermobaric charge- the ability to go around corners. During one of it's first few tests, the BLU-118/B was found to
be capable of sending it's blast/heat waves around a horshoe- shaped bend in a test tunnel complex in the Nevada desert. It's likely nothing more
than a heat-driven pressure spike, but the ability to control or "bounce" a blast wave around a corner sounds like a nice challenge, especially once
you get "mach stem" effects mastered. Thanks for the -135 mix. Where did you find it?
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HMTD
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Couple months ago I’ve tested EBX charge consisted of 21.5 g PBX center charge ( D=18 mm, 92.5/7.5=PETN/Polybutylene with d=1.62 g/cm3 and calc.
VoD=8026 m/s and calc. P=26.3 GPa) and about 20-23 g Solid Fuel shell ( inner D=18 mm, outer D=25 mm, 70% ultra fine sph. Al(85)-Mg(15) , 25% NH4NO3
, 5% Polybutylene , d=1.5 g/cm3 ). So the total weight was about 45 g with explosive to fuel ratio ~ 1. EBX charge was placed in old felling to
simulate partially closed volume. Two beer bottles were placed at different distances ( ~30 and 40 cm) from charge and also two plugged Al beer
bottles (~50 and 70 cm) as pressure witnesses. The blast effect was much louder and with longer echo, I was (staying at 15 m away) a little stunned
(maybe because the interference of blast waves had been reflected from the rear walls). So I would assume the total power was about 50-80 g TNT ( Of
cause, it’s all very subjective, but several independent people (not knowing what the charge was, by video) said it was about 50 g TNT. Glass
bottles were completely destroyed, closest Al bottle was slightly shrunk by blast wave, the second stayed untouched.
Vids&photos here:
http://rapidshare.com/files/35011853/Test.rar.htm
password to archive: 232348sdbjsdfgasmsuertr8wdaseke45yefajsd
[Edited on 6/4/2007 by HMTD]
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pinky
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Here is the source of composition PBXIH-135(PBXN-113)
and cool article "Optical Pyrometry of Fireballs of Metalized Explosives" from Propellants, Explosives, Pyrotechnics
-it's about testing a charges composed from metallic particles saturated with sensitized NM.
http://rapidshare.com/files/35054170/Metalized_Explosives.ra...
the password to archive: PBXN-113
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Marsh
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It does seem that the aluminum surrounds go on to react with the air with moderate means of pressure/dispersal/heat - although as to how efficiently I
do not know.
I viewed one blasting cap closely to get an idea of sound and light when it detonated.
I then placed a duplicate 1.5g cap inside of a film container containing a small amount of 400 mesh aluminum powder around it.
The noise produced by the latter was quite noticeably louder, and a large flash fireball was also witnessed. The container and surrounding area still
contained spread aluminum powder, so it was not all utilized. However enough of it was to notice a considerable effect.
This makes me ponder the idea of a peroxide water gel containing 50% aluminum as a possible useful surround charge covering something like a PETN PBX.
[Edited on 4-6-2007 by Marsh]
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E-tech
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If you were to try that experiment again, an easier idea wouls be to use a container with a heavier wall than a film canister. The confinement would
allow the heat/pressure from the cap to spend a bit more time working on the Al powder, heating it to the point of ignition. The timing of that
ignition is all important in this type of system. This can be determined through experiments with various Al particle sizes used in different charge
diameters and with different casing strength. When the research was being conducted, it was found that 240um sized aluminum particles wouldn't ignite
reliably until charge diameters were about 35cm. Below that, the Al would move ahead of the blast wave, and, even if it ignited later- it's burning
would not contribute any aid to the initial blast wave. The three effects they found were1)immediate reaction of the Al behind the blast wave,
assisting in it's formation/movement. 2)delayed/inconsistant reaction of the Al, which contributed little to the blast effect (most home experiments
would likely be in this category) and 3)failure of complete Al ignition.
Adding 10 to 25% of an energetic material to the aluminum would also aid in it's complete combustion. double or single-based propellants should work
fine for this. If you have a good amount of a single size of Al powder, then adjusting the strength of the container, adding an energetic material to
the Al, and finally, increasing the size of the charge should allow you to fine-tune the design till you get the noticable effect. The problem is
scaling up your experiments. The same size Al particle may not work in a larger design- casing, energetic binders, etc, all will need to be
re-evaluated. The idea is to find what is called the "Critical diameter for particle ignition". An immediate ignition of the Al after the initial
reaction of the explosive is the best way to get the desired effect. Flourine containing compounds ("inter-halogen oxidizers") are often used as a
coating of the Al because it has been found that a telfon/viton coating of the Al will reduce the initial reaction energy requirements. A good ratio
to start would be equal parts by weight of surround to explosive. Some designs go as high as 10 parts surround to 1 part (by weight) of explosive
charge- these require a full 25% of an energetic binder for the Al, however. Monopropellant liquids are a good choice for this, but evenly dispersed
gunpowder mixed in the Al will work, as may a high concentration of peroxide (I'd use 25% of my strongest peroxide and 75% Al)
Marsh- you said you used a 1.5 gram cap in your film canister experiment. 1.5 grams of what? and, where did you obtain the 400 mesh Al powder?
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Marsh
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Sorry, it was a 1.5g PETN cap.
The Al came from a barrel of unknown use.
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nitro-genes
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Nice one HMTD, definitely looks like an effective charge to me. The energy transferred to the rear wall of the felling appears much larger than can be
expected from 21 grams of PBX alone. I think your fuel/PBX ratio of 1 is better than the 10:1 that I used, especially unconfined. How important is the
density of the surround btw? Higher densities and plasticizing would yield higher pressures over the decreased distances and improved shock
transmission of the PBX to surround. Is this why you plastized the surround as well? Never thought about this. Like E-tech suggests, I reckon that most of the aluminium reacted long after the initial blastwave thus not aiding
much in increasing the blasteffect in the simple setup I used. It would be nice to compare one of these surround EBX of yours with an equal weight of
70/20/10 PETN/Al/Pib aluminized PBX. The lowering of the activation energy for the aluminum particles is interesting as well. Teflon grease and spray
are cheap and could be used to treat the aluminium powder to give better results.
PS, I tried your KNO3 PBX variant as well, though it seems to be pretty hard to detonate, would the KNO3 be replaceble by something like KClO4? (of
course not mixing the Al and KClO4 together prior to plasticizin, which would be pretty dangerous )
[Edited on by nitro-genes]
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HMTD
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| Quote: | Originally posted by nitro-genes
Higher densities and plasticizing would yield higher pressures over the decreased distances and improved shock transmission of the PBX to surround. Is
this why you plastized the surround as well? |
Well, I think the same way - the denser the fuel=> the thinner the layer of it (with the same fuel mass) and lower the attenuation of initial blast
wave from the PBX center(less dens.=>more air hollows=>energy consumption on air shrinking&heating ). So, the greater would be fuel speed
and it’s temperature, faster the reaction with air and more energy would go to the increasing of the total blast effect. And you know better than me
that plasticizing is pretty good and relatively easy way to increase density of anything in form of powder.
| Quote: | Originally posted by nitro-genes
I reckon that most of the aluminium reacted long after the initial blastwave thus not aiding much in increasing the blasteffect in the simple setup I
used. |
This is also seems to be reasonable, but the speed of reaction of Al oxidation probably depends on Al particle size, its the temperature and speed,
presence of oxidizing gases ( NOx, O2, CO2 etc.) and its concentrations. My example shows than fuel burns so quickly, that it forms the additional
blast wave, probably with elongated zones of high or/and low pressure like in case of thermobaric explosives. I don’t know, separated the initial
wave from the additional, or the charge forms just one enhanced blast wave (which probably would be better).
| Quote: | Originally posted by nitro-genes
It would be nice to compare one of these surround EBX of yours with an equal weight of 70/20/10 PETN/Al/Pib aluminized PBX. |
I think EBX would be significantly better than aluminized. Let’s see: The VoD of your composition would be ~ 7100 m/s, P ~ 18 GPa since, as you
know, Al is inert in PBX. So, the result speed of Al particles will be the same as those for detonation products ( which also poor with oxidizing
substances) and maximum what you can get is the enhanced sound & flash with no extra blast wave – so the explosion would be like the same charge
of picric acid + extra flash and sound.
| Quote: | Originally posted by nitro-genes
I tried your KNO3 PBX variant as well, though it seems to be pretty hard to detonate, would the KNO3 be replaceble by something like KClO4?
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Sensitivity for any PBX(>30% explosive) depends on explosive %, its particle size and density. So it doesn’t matter KNO3 or KClO4 you will use,
though the total power with KClO4 can be greater. I used KNO3 because it is cheap, and that type of PBX was just for fun like firecrackers. It better
to use NH4NO3 but it is hydroscopic…
[Edited on 6/8/2007 by HMTD]
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nitro-genes
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| Quote: | | I think EBX would be significantly better than aluminized. |
There is a limit of course to the extend by which you can keep adding aluminium to any explosive while still beeing detonable. So, the higher fuel/PBX
ratio in a surround charge wil result in a much larger total energy release, but only if all of the fuel is efficiently utilized in the shortest
timeframe possible. This is no problem for aluminized compositions since all the aluminium particles in an aluminized composition are subjected to the
peakpressure of the detonation and for longer times than for the aluminium particles in a surround charge. Even in oxygen poor compositions there will
be a lot of water and CO2 present after the detonation to react directly with the aluminium. So I believe that aluminized explosives would give faster
reaction times for the aluminium than for any surround, which makes them much easier to work efficiently and aid more effectively to the blastwave.
This is how I see it anyway, the closer the secondary combustion follows the inital blastwave the more it adds to it...
| Quote: | | Sensitivity for any PBX(>30% explosive) depends on explosive %, its particle size and density. So it doesn’t matter KNO3 or KClO4 you will
use, though the total power with KClO4 can be greater. |
I know you use the enthalpy of formation to determine whether a compound will act as an inert (absorp energy) or release energy to add directly to the
shockwave. Though the lower activation energy for decomposition and/or higher energy release upon decomposition make that KClO3 is detonable on its
own, while KNO3 isn't. So wouldn't there also be a difference in the amount of energy that needs to be absorbed by the oxidizer salt in order to
release more energy by the reaction of its decomposition products? A composition containing a large percentage of KNO3 would therefore need a larger
initial shock than one containing a large percentage of KClO3 or KClO4, no?
Anyway, the water resistance, higher energy and oxygen content, and higher density seemed advantageous to me.
[Edited on by nitro-genes]
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HMTD
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| Quote: | Originally posted by nitro-genes
This is no problem for aluminized compositions since all the aluminium particles in an aluminized composition are subjected to the peakpressure of the
detonation and for longer times than for the aluminium particles in a surround charge. Even in oxygen poor compositions there will be a lot of water
and CO2 present after the detonation to react directly with the aluminium. So I believe that aluminized explosives would give faster reaction times
for the aluminium than for any surround, which makes them much easier to work efficiently and aid more effectively to the blastwave.
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You can believe in whatever you want, but there is a fact: for some reason the design of aluminized explosives charges was changed to more complex by
separating HE from aluminium and sometimes by adding extra oxidizer and binder. And this was made for one reason – to achieve 100% combustion
efficiency. (Do you see some accordance with the SC – the more complex is design (liner, lens, etc) - the more efficient the SC?). For additional
info, see US6969434 , US5996501, US5467714 and related.
| Quote: | Originally posted by nitro-genes
A composition containing a large percentage of KNO3 would therefore need a larger initial shock than one containing a large percentage of KClO3 or
KClO4, no? |
No, the difference in initiator mass would be hardly noticeable (in equal conditions – the same partial density of the same HE, additives particle
size). All these additives (until them nano-sized, even KClO3) not reacting before the C-J, so there is no influence on detonation parameters (VoD,
P, n). But I never told anything about after-reacting – there is no doubt, that more reactive components will react easier, producing more heat and
pressure. But when using such powerful oxidizer like KClO4 there is no need to use HE at all – the KClO4/Al/S flash is one of the powerful
non-explosive things I’ve ever saw. Just use card tube and the fuse.
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E-tech
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A patent that uses perchlorates mixed with the Al surround in the warhead design:
US6955732 Advanced thermobaric compositions
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tito-o-mac
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I would like to know whether I can make TBX(thermobaric explosives) with Nitrogen trichloride, or chloride or azode with aluminium powder. If it is
possible, I would also like to know the detonation velocities of Nitrogen trichloride and the ratio of the mix.Thanks a dozen to everyone for giving
the information! Thanks!
Oh... 1 more very important question! In the discovery channel video, the expert said "the secondary charge will go off sometime after the explosion"-
to ensure that the liquid is properly dispersed and ignited... So must all thermobaric explosives undergo a secondary explosion sometime after the 1st
one to properly achieve the required properties of the detonation?
[Edited on 30-6-2007 by tito-o-mac]
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not_important
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NCl3 detonates sooner than you think, such as on contact with many organic materials. I would not like to mix it with aluminium, except by remote
manipulation.
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tito-o-mac
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So what is the ratio of high explosives do I use? Petn or RDX : AL mesh
[Edited on 1-7-2007 by tito-o-mac]
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tito-o-mac
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Here, maybe this may be something useful to you guys.
------------------------------------------------------------------------------
Attachment: Fuel Air Explosive Systems.pdf (278kB)
This file has been downloaded 1944 times
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TBX
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These weapons work by mixing one or more reactive metals with a monopropellant and then placing this as a "surround" around a charge of conventional
high explosive. The detonation of the high explosive causes the surround to react after the initial event,which is the main effect of these weapons. I
thought this quote from patent 4331080 summed up these weapons quite well.
(1) The high rate of pressure generation or shock induced by the conventional high explosives causes shock initiation of the boron and the metal or
other metal compounds to form the intermetallic compounds. The initiation mechanism is thought to be one of temperature elevation to the autoignition
temperature of the boron and the metal or other metals which form the intermetallic compounds by shock compression of the distended mixtures.
(2) The resulting implosion of the boron and the metal or other metals to form the intermetallic compounds causes outward moving pressure waves to
reflect on the inward moving shock waves. The reflected waves, generally more intense, (greater magnitude and shorter time) than the original waves
enhances the fireball effect of the molten intermetallic compounds causing molten metal droplets to react violently with the oxygen in the explosive
reaction environment.
(3) Interaction with the ambient environment causes tertiary burning and cratering to occur resulting from the adiabatic reaction temperatures, at
least 3,000.degree. K., and generally within a range of 3,000.degree.-4,000.degree. K., and the high pressure shock generated. Confined composite high
explosives when cast or consolidated to pressures ranging from 5,000 to 20,000 pounds per square inch with a column to diameter ratio of 2:1, provides
detonation rates of 4-5 millimeters per microsecond. The sensitivity and stability of the composite high explosive is equivalent to the conventional
high explosive used in the composite formulations.
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Marsh
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So this would go on to mean that it is more appropriate, based upon description, to use a surround of different composition rather than a continuous
phase of thermobaric explosive, as the colliding shockwaves increase the reactivity with the air in the afterburn event.
That is interesting, I did not ever imagine this event helping the afterburn like this. Sounds as if the vacuum/pressure differences actually help to
mix the fuel more intimately with the air.
[Edited on 11-7-2007 by Marsh]
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TBX
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| Quote: |
So this would go on to mean that it is more appropriate, based upon description, to use a surround of different composition rather than a continuous
phase of thermobaric explosive, as the colliding shockwaves increase the reactivity with the air in the afterburn event. |
This is basically the difference between a reactive surround explosive and a thermobaric weapon.
" There are four types of recognized enhanced-blast explosives: (1) Metallized Explosives. (2) Reactive Surround. (3) Fuel-Air. (4) Thermobaric."
http://das.cs.amedd.army.mil/PDF/J04_4_6.pdf
Also,I found these pictures interesting. The secondary combustion is clearly visible in both.
http://www.spiegel.de/img/0,1020,677918,00.jpg
http://pdn.philly.com/2005/05/13/mac/08.jpg
[Edited on 12-7-2007 by TBX]
[Edited on 12-7-2007 by TBX]
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tito-o-mac
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woah... someone called ThermoBaric eXplosives in a thermobaric forum! Do u have
any experience in thermobaric explosives?
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www
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just russian video.
Attachment: thermobar.wmv (515kB)
This file has been downloaded 1755 times
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Marsh
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| Quote: | Originally posted by www
just russian video. |
I'm trying to figure out what is being shown in the scene at 12 seconds into the video. It looks like a line of charges is simultaneously detonated on
the ground, but to me they do not look thermobaric, simply incendiary. Maybe I am wrong for those that know Russian.
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tito-o-mac
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The vehicle is TOS-1 buratino. It's something like the Multiple Launch Rocket System, except it fires rounds of rocket-armed thermobaric missiles to
level house block by block. Its currently deployed in Chechnya. As it is empties its payload of 30 rounds/15 s, its probably capable of doing that. Or
it fires them at different angles. The rounds take longer to reach the ground when fired at higher angles. The rounds take less time when fired at
lower angles. So if a computer was to do or the number crunching, that feat would have been possible. First fire a round at a highest angle, then
slowly fire the rest of the rounds at a angle lower than the other, an they will at that the same time at the same target!
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