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Author: Subject: Thermobaric explosives
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[*] posted on 14-7-2007 at 21:23


Quote:
Originally posted by Marsh
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.


Give me your E-mail. I will send this movie. It's on Russian. But, they are very nice data who don’t need translation
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[*] posted on 23-7-2007 at 12:42


Metallized explosives are more usefull in enhancing the blastwave of explosives used at high altitudes (where less air is available for the blast wave to work on/in)- it's why they see a lot of use in air-to-air missiles, but they would be pretty close to ideal, if it wasn't for the aluminum burning just a bit too fast (according to the design criteria set down by various researchers working on this type of ordnance). The reactive surround type of warhead I have heard described as a thin metal casing filled with powdered aluminum and nitrocellulose based propellants. With a bursting charge, this may be pretty effective, but most of the reactive surround warheads in use have powdered aluminum with a monopropellant liquid, or a flourine-based binder (that may or may not have an energetic binder). Separating the aluminum may provide a delay long enough to get a better effect on target, but, 4 pounds of metallized explosives at just over 100 meters will knock you over. I wish I could find a source for powdered aluminum where I am, so I could test the idea. The ordnance itself just isn't available to play with. Pity.
Has anyone found any info on the Russian thermobaric submunition? I have no russian language skills, but the things seem to be filled with an aluminized ANFO type mix. Any got anything new on them?
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[*] posted on 24-7-2007 at 08:20


"4 pounds of metallized explosives at just over 100 meters will knock you over"

Where did you read that? It takes 1 - 1.5 PSI to knock a person to the ground. Taking the cubic scaling law, this equals 1 - 1.5 million PSI from one meter, or 2 billion PSI at the charge radius. Doubtful...

Taken from the a.e.e archive (cant format it here, paste into excel):

Scaled Distance Overpressure Consequences
Z (ft-kg1/3) (psi)

3000-890 0.01-0.04 Minimum damage to glass panels
420-200 0.1-0.2 Typical window glass breakage
200-100 0.2-0.4 Minimum overpressure for debris and missile damage
82-41 0.5-1.1 Windows shattered, plaster cracked, minor damage to some buildings
44-32 1.0-1.5 Personnel knocked down
44-28 1.0-1.8 Panels of sheet metal buckled
44-24 1.0-2.2 Failure of wooden siding for conventional homes
28-20 1.8-2.9 Failure of walls constructed of concrete blocks or cinder blocks
20-16 2.9-4.4 Self-framing paneled buildings collapse
20-16 2.9-4.4 Oil storage tanks ruptured
16-12 4.4-7.3 Utility poles broken off
16-12 4.4-7.3 Serious damage to buildings with structural steel framework
11-10 10-12 Probable total destruction of most buildings
15-9.0 5.1-4.5 Eardrum rupture
14-11 5.8-8.7 Reinforced concrete structures severely damaged
14-11 5.8-8.7 Railroad cars overturned
6.7-4.5 29-72 Lung damage
3.8-2.7 102-218 Lethality
2.4-1.9 290-435 Crater formation in average soil

[Edited on by Boomer]

[Edited on by Boomer]
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[*] posted on 24-7-2007 at 09:59


With all fuel-air explosives, including thermobaric charges you can't simply take the charge radius for the detonation pressures produced. It doesn't react in a C-J like manner like an ideal explosive, instead the burster charge disperses the fuel to obtain a volume a 100-1000 fold of the charge volume itself in order to react with the atmospheric oxygen. That is why the total energy released can be so much higher than with conventional explosives and can do more work over a greater distance.

[Edited on by nitro-genes]
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[*] posted on 25-7-2007 at 07:32


The 2 billion PSI was just for comparison with CJ shockwaves. Take the 1.5 million PSI at 1 meter if you want. A 2-meter fireball is likely in the right order, still a million PSI cannot be reached at the outer surface of a fuel/air cloud.

The number simply does not sound right, there are people here (or on E+W) who stood much closer to a similar charge, the closest I remember is either 7 or 10 meters from 10 kilos of ammonal. If you are knocked over at 100m, these people would have been thrown quite a distance, or - if already on the ground - crushed to death. One tenth the distance means between 100 and 1000 times the peak pressure, depending whether it's still a hot expanding gas cloud (cubic rule) or down to a sound wave (square rule).
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[*] posted on 25-7-2007 at 08:25


7-10 meters from 10kilos of ammonal? Sounds a bit close if you ask me.

Was this placed above the ground with no barrier between them?
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[*] posted on 26-7-2007 at 07:22


Too close for my taste also, even with earplugs. From what I remember the charge was in a paint bucket, inside a rotten tree, person was out of fragment path (another big tree or boulder, don't remember).
The closest I woul like to be from 10 kilos would be 20-25 meters, the shock drops more than one expects with distance. Less than 100g plastique gave me a much harder punch from 2.5 meters than 3 pounds on ANFO from 15m (both times crouching behind a concrete wall).

About the energy content of thermobaric/enhanced blast/... explosives, it can be a few times that of conventional HEs. The limit are FEAs with only a fragment of the charge weight HE, most of it fuel. Just compare the 4kJ/kg of TNT with the ~40kJ of petrol. The usual fuels like ethylene/propyleneoxide are lower than pure hydrocarbons, but not that much lower.
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[*] posted on 27-7-2007 at 00:42


I was wearing earplugs, and safety glasses, body armor, and an M-4 rifle (can you guess where this happened? Hint: think sand). I didn't read those numbers- I fired the weapon (SMAW-NE) myself, and we used a range finder on the house I hit to confirm the distance. One thing we noticed was that people in armor were more affected by the blast than those not wearing any. The trauma plate acts like a nice flat surface for the pressure to act on; Thermobaric weapons make your body armor work against you.
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[*] posted on 27-7-2007 at 17:36


Here's a short video of the Hellfire Metal Augmented Charge being tested.

https://mfcbastion.external.lmco.com/mfc/videolibrary/HELLFI...
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[*] posted on 5-8-2007 at 00:21


Yeah, they say that wearing bullet proof armour worsens the damage as it increases the surface area of the human to get hit by the blast wave. Below is a question I was still pondering on:

Say, a thermobaric explosive is one that "disperses the cloud the and ignites it with the same charge" how does one do that anyway? Is it something like a RPG ignition where a piezoelectric fuze is used? E.g. when the charge goes off, the liquid is dispersed and the sensitive piezolectric fuze ignites the cloud right after the first blast goes off?
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[*] posted on 5-8-2007 at 01:06


Well, I read up on it years ago but I remember that finely spread Al had something to do with it in some types of thermobaric explosives. The Al would ignite as soon as enough oxygen was available and set off the kerosene or whatever combustible was spread. It looked really effective in the video and it ensures that ignition always happens under the same conditions which makes a lot of sense.



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[*] posted on 5-8-2007 at 14:37


Aluminium powder doesn't need to react with oxygen, as most of the aluminium will be oxidized by the water, CO2, CO etc released during the detonation. The aluminium particles accellerate along with the detonation products, with a burntime determined mostly by the particle size of the aluminium. For igniting a dispersed vapour cloud, larger particle sizes do just as well or even better than expensive high mesh grades. Especially titanium keeps burning very long...

Anyway, I was thinking about these surround EBX charges in which HMTD used AN as the oxidizer additive. AN has a low decomposition temp, good oxygen balance and stability and is very cheap as well, the only disadvantage is that it makes the charge very sensitive to moisture.

How about about using urea nitrate instead? Slightly lower decomposition temp, higher density, not hygroscopic and easy to come by. Acidity is much higher though and could prove to be a problem in combination with the aluminium when not recrystallized to remove any remaining nitric acid impurities. With completely dry UN this shouldn't be a problem though...

Does anyone has experience with urea nitrate in combination with aluminium powder?

Another option would be to use aluminized AN-emulsions for the surround, maybe this is what was meant with the ANFO thermobarics mentioned earlier in this topic. Reverse emulsions are water resistant and form a soft pasty substance when warm, which allows the aluminium to be mixed in easily, although density will not be as high as for an plasticized and rolled surround composition.

[Edited on by nitro-genes]
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[*] posted on 6-8-2007 at 06:11


A better choice would be the perchlorate salts. It's what is used in the China Lake wepons research facility patent for a castable thermobaric explosive. One of the inventors, May L. Chan was (I believe) the leader of the project that devised the filler for the BLU-118 thermobaric bomb. The annular ("surround") design in the castable explosive patent would be perfect for rocket/missile warheads.
It's likely that the Russians are using AN emulsions in a few of their thermobaric designs (low cost, and they don't have a problem with storing liquids in a warhead like the U.S. does), but, no one can find the proportions they are using.
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[*] posted on 6-8-2007 at 12:55


oops- Anh Duong was the researcher in charge of the BLU-118 project, and works on the east coast. May L Chan is on the west coast.
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[*] posted on 9-8-2007 at 19:59


Granted a storable stable unreactive and insensitive energetic substance is a
requirment for deployable items of ordnance. This is only an idea , Triethylaluminum
is utilized for special purposes , metal ethoxide's are much less reactive , so why
not blend the two. Their detonation would produce incandescent alumina dust
and Butane gas . ( C2H5O )3Al + ( C2H5 )3Al -> Al2O3 + 3 C4H10

.
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[*] posted on 10-8-2007 at 00:42


So what is the best or most suitable metalized powder or liquid for FAE or TBX explosives? I think the Russian's usage of AN combination is a good choice as it produces a loot of excess oxygen, making igniting conditions favourable. Doesn't ANNM do just the same?

[Edited on 10-8-2007 by tito-o-mac]
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[*] posted on 12-8-2007 at 14:25


Actually, triethylaluminum is already in use- as a flame weapon- the M202 "FLASH" incendiary rocket uses it. It's pyrophoric, so storage is a big problem (I've never seen one of these rockets used in combat- effective, but politically nasty. And, damaging the container it comes in could ignite the thing), plus, the U.S. doesn't like using liquids in it's ordnance- even the most durable design will likely start leaking within ten years.
There is no "most suitable metalized powder or liquid"- it all depends on the design of the overall ordnance system. Even the size of the powdered aluminum has to be changed, depending on the size of explosive charge it is used with (check "effects of scale on the blast wave from a metalized explosive"- a google search should get the paper, just enter the title).
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[*] posted on 15-8-2007 at 06:08


Hey, check out this HMTD hexamine thermobaric bomb this guy made. I'm not convinced though: http://www.youtube.com/watch?v=dhZEeUsTrNM
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[*] posted on 16-8-2007 at 09:09


He's an idiot. It's just a primary (-151% OB!) diluted with an inert that happens to be flammable. Like dynamite with twice as much wood pulp. It would not even detonate if it was no primary.

Plus, he seems to use it like a fun snap (torpedo), there must have been some ball bearings or stones in that wrap-up to explode on impact. About as unsafe as it can get.... :mad:
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[*] posted on 12-9-2007 at 06:18


The Russians just detonated what they are calling the most powerful thermobaric airdropped munition ever. According to Russian news sources, the bomb has four times the yield of the largest such US device (MOAB) at 44 tons vs 11 tons TNT equivalence, yet the explosive is about 95% of the mass of the explosive used in the US device.

Sounds like warmed over Cold War rhetoric. They are claimning a major breakthrough in thermobaric explosives technology.

This comes at a time when indeed relations between Washington and the Kremlin are at a post 1990 nadir.

Any beef on this bun?
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[*] posted on 12-9-2007 at 06:37


yeah I just posted about this on my Home Forum, here`s some links:


http://www.reuters.com/article/worldNews/idUSL11559523200709...
http://www.freemarketnews.com/WorldNews.asp?nid=48780
http://www.1tv.ru/owa/win/ort6_videopage.main?sender=news&am...




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[*] posted on 12-9-2007 at 06:52


Quote:
Originally posted by Sauron
the bomb has four times the yield of the largest such US device (MOAB) at 44 tons vs 11 tons TNT equivalence, yet the explosive is about 95% of the mass of the explosive used in the US device.


MOAB is an aluminised HE thermobaric, composition H6 which is 29.5% TNT, 44% RDX, 21% Al (remainder being inerts), whereas the russian bomb is a true FAE. See youtube movie at 25sec.

http://youtube.com/watch?v=iCmA7xFPIdU

edit: Movie above is same as last link YT2095 posted, which is better quality.

[Edited on 13-9-2007 by Axt]
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[*] posted on 12-9-2007 at 07:17


IMO the claims of equivalence to a nuclear weapon are absurd; off by 3 to 7 orders of magnitude. Pure propaganda.
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[*] posted on 12-9-2007 at 07:27


are you Mental? ever heard of Battle Field "Tactical" nukes? Tank launched shell or MLRS types?



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[*] posted on 12-9-2007 at 08:28


Yeah, they DO go down to 50-100 tons TNT (= only 1- 2 times the russian FAE!), usually adjustable via detonation (implosion) pattern.

Still what most people think when they hear nuklear is more like 50-100 kilotons...
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