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Author: Subject: Unconventional Shaped Charges
searat
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[*] posted on 25-2-2005 at 05:25


try a trangle, on sky with that deM program they used detcord copper trangle no stand off(small amount per area) and they cased it in rubber(which i think was used to bounce a shockwave back into the explosive to aid in ignition,and force the copper/plasma to get diercted.)

"Plasma? .. theres no plasma. " are you drunk when a explosive goes off it turns into plasma.
I know you don't think what i said was right but try this.

Timeline
1sec)the explosive is set off.
2sec)the temp rasies to 10,000C,and electrons spreed(like how a ark is greated,just before that)
2.5)electrons engise conductive metals,produceing a magntic feild.
2.6)most of the explosive has decomposed, the copper starts to turn to plasma,losing its field turning into a jet, with the shockwave and replie it speeds up to high speeds.
2.8)A plasma mass is made, due to the desnity of the metal more plasma per inch. copper is more conductive it easyly excepts electrons, breaking down quicker

I think heat conductive has some thing to do with it,add to last statment please!


[Edited on 25-2-2005 by searat]

[Edited on 25-2-2005 by searat]
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[*] posted on 25-2-2005 at 08:18


Quote:
Originally posted by searat

"Plasma? .. theres no plasma. " are you drunk when a explosive goes off it turns into plasma.


Axt knows what he's talking about. You don't. Do some more research.:P Also learn to spellcheck-
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[*] posted on 25-2-2005 at 08:28


Quote:
Originally posted by searat
Timeline
1sec)the explosive is set off.
2sec)the temp rasies to 10,000C,and electrons spreed(like how a ark is greated,just before that)
2.5)electrons engise conductive metals,produceing a magntic feild.
2.6)most of the explosive has decomposed, the copper starts to turn to plasma,losing its field turning into a jet, with the shockwave and replie it speeds up to high speeds.
2.8)A plasma mass is made, due to the desnity of the metal more plasma per inch. copper is more conductive it easyly excepts electrons, breaking down quicker


So all this happens in 2.8seconds huh? Well I guess you sure learned us then:P
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[*] posted on 25-2-2005 at 10:23


I allways believed that in any conventional flame there was plasma. At least some amount of electrons and positive ions reacting and producing characteristical spectrum lines. The detector of Gas Chromatograps (TCD or FID) also presume the existence of ions in a flame isn´it?. Well, I humbly don´t understand how the plasma works in a shaped charge, but there must be plasma.
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Axt
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[*] posted on 25-2-2005 at 14:43


I apologise in assuming that you were talking about a jet of plasma doing the work, or are you? "the copper starts to turn to plasma, losing its field turning into a jet"? I can't tell what your talking about, it seems youve made a wrong assumption that you think is common knowledge.

It's a common misconception that plasma is responsible for the cutting effect of shaped charges, when its little more then a solid extrusion of the liner. Ionised gas is present, yes, in the explosion, not the jet.
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searat
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[*] posted on 25-2-2005 at 17:44


"the copper starts to turn to plasma, losing its field turning into a jet"? Metals close to a explosive can vaporise(plasma),while the copper is solid it can produce a magtnic field, when it vaporises it loses its field.

"a solid extrusion of the liner. " does that mean it fires a solid object.

I'am guessing your right about it not being a jet of plamsa, but just think what it would be like if it did,as a plasma cutter can slice through AL 120mm like butter

"So all this happens in 2.8seconds huh? "
i don't know the timeline, but it would be in milseconds, and as it wasn't bast on fact(that i know of), just my thoery, i could have used mintes.

[Edited on 26-2-2005 by searat]

[Edited on 26-2-2005 by searat]
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[*] posted on 25-2-2005 at 17:48


Am I missing something completely?

What's a magnetic field got to do with a liner, and a shaped charge? Should we be using ferromagnetic compounds or what? What are you on about?

Further, your spelling... where shall I start? Anyone can do a spellcheck and so can YOU!




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searat
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[*] posted on 25-2-2005 at 17:54


"What's a magnetic field got to do with a liner, and a shaped charge? Should we be using ferromagnetic compounds or what? What are you on about? "

if you say a shape charge push the copper through the target, then using ferromagnetic compounds would greatly incease its effectiveness as it would offer some protection from the plasma.

"liner" does this meaning a shokwave warhead?
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[*] posted on 25-2-2005 at 18:00


Oh dear.... I smell a troll...



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[*] posted on 25-2-2005 at 18:07


Whats a troll?.

I'am not going to change my mind, shape chage uses plasma to cut.

"The shape charge is an explosive warhead with its forward face hollowed out into a cone, which is then lined with a thin metal liner. If the charge is now detonated from its rear end, away from the liner, the effect of the detonation wave passing through the explosive is to deform the liner, subject it to immense pressure and heat, and turn it into a jet of molten metal and explosive gas moving at speeds in the region of 7-8,000 meters per second. When this jet strikes armour plate it simply forces a hole in the armour due to its combination of heat,mass and high velocity.
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[*] posted on 25-2-2005 at 19:45


That quote doesn't mention plasma. The salient feature of plasma is near complete or complete ionisation. You've failed to argue that the jet is ionized to any significant extent (not to mention that your own quote says it's not all gas -- "molten metal" rather than "vaporized metal"!). Moreover, ionization of the fluid has nothing to do with cutting ability; the things that make a difference are listed by your quote, such as velocity.

You don't know what a troll is? I guess you are an Internet newbie too, not just a chemistry one. Check Wikipedia. Oh, wait, you probably don't know what that is either. http://en.wikipedia.org/wiki/Internet_troll

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[Edited on 26-2-2005 by Quince]




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[*] posted on 25-2-2005 at 21:33


Heh, I checked the wikipedia entry for "shaped charge", it's been corrected as it used to mention plasma as well.

Anyway enough of this discussion on plasma jets, its simply false. Even your own quote searat contradicts your argument. Its alright to come up with theories, but you have to base them on facts.

The following info is originally from:

von Holle, W. G, and Trimble, J. J. (1976), "Temperature Measurement of Shocked Copper plates and Shaped Charge Jets by Two-Color IR Radiometry," J. Appl. Phys. 47(6):2391-2394.

von Holle, W. G, and Trimble, J. J. (1977), "Temperature Measurement of Copper and Eutectic Metal Shaped Charge Jets," Ballistic Research Laboratory Report.

Quote:
The temperature of a jet from a 81.3mm diametre, 42° apex angle conical copper liner was measured. The explosive fill was comp B and a four-shot average of the jet temperature was 432°C with a standard deviation of 76°C.

Also measured the jet temperature of a 60° apex angle, 81.3mm diametre, tin/lead eutectic liner. The liner wall thickness was 2.54mm and the explosive fill was Comp B. The conical apex was slightly rounded to a 1mm radius. A four shot average revealed a jet temperature of 569°C with a standard deviation of 34°C. The tin-lead liner had a tip velocity of 6.3 km/s compared to the copper liner jet velocity of nearly 8 km/s (presumably liners of same dimensions).

It was concluded that the copper jet was solid and the lead-tin jet was liquid in spite of any scatter in the data.


[Edited on 26-2-2005 by Axt]
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searat
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[*] posted on 8-3-2005 at 21:18


Damn i hate to be wrong, but thanks for the info. If a shape charge uses the liner as a projectile, how would you incease its depth without useing more powerfull explosive?

" turn it into a jet of molten metal and ""explosive gas"" moving at speeds in the region of 7-8,000 meters"

That quote doesn't mention plasma?


[Edited on 9-3-2005 by searat]
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[*] posted on 9-3-2005 at 23:46


Quote:
Damn i hate to be wrong

That's not good, because it can affect your judgement of whether you are wrong (and when to consider it). And that equates to stubborness.




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[*] posted on 12-3-2005 at 19:36


"whether you are wrong (and when to consider it). "
Yes people can be blind can't they, even internet infomation can be right at times.

Stop blowing the mods/boss's .

GIVE ME THE FACTS WHY I'AM WRONG NOT JUST SOME fm THAT HAS A NICE TITLE.

[Edited on 13-3-2005 by searat]
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[*] posted on 16-3-2005 at 08:45
unconventional shaped charge


hi friends
i have been doing experiments with shaped charge (lead liner ,90 degree cone dia,RDX ,BASED FLSC)for cutting 100 mm diameter steel tube by keeping FLSC INSIDE.BUT THE RESULT WAS POOR.is the 60 dergee cone angle better.what is the solution for the solving jet divergence during bending.
i had serch various book like fundamental of shaped charge but nothing is said about above things.in some report in net i found out 60 degree is better.i want to conferm and know the reson also.
please

Edit by chemoleo: Don't double post, and DO search before you post in the first place. This is the thread where you want to post it.


[Edited on 16-3-2005 by chemoleo]
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[*] posted on 16-3-2005 at 09:13


Two cones joined at the apex, filled with explosive, initiated from the centre. Patent searches would be the best place to look, as this is common practice in the oil industry.



[Edited on 7-6-2005 by chemoleo]
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Quince
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[*] posted on 16-3-2005 at 12:47


Is this better than the configuration where the explosive is outside the pipe, with the two (wraparound) triangles meeting at the cutting line? By better, I mean using less total amount of explosive needed to succeed cutting a given pipe.

[Edited on 16-3-2005 by Quince]




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[*] posted on 17-3-2005 at 00:39


pic

1.jpg - 630kB
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searat
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[*] posted on 17-3-2005 at 00:49


pic

2.bmp - 186kB
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pramodattingal
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[*] posted on 17-3-2005 at 07:48
unconventional shaped charge


does the two cone answer was for me.
how can be it assembled inside the pipe
can u make me clear
my question related to 60 and 90 degree is unanswered

[Edited on 17-3-2005 by pramodattingal]
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[*] posted on 17-3-2005 at 09:00


@Axt:
Excuse the simplicity of the question ;).....Some very impressive pictures taken....how did you protect yourself from shrapnel?

[Edited on 17-3-2005 by BASF]
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[*] posted on 17-3-2005 at 09:20


Quote:
Originally posted by Quince
Is this better than the configuration where the explosive is outside the pipe, with the two (wraparound) triangles meeting at the cutting line?


I would expect the one above would be more efficient, especially for thicker pipe. Though I expect if given the choice most would attack it from the outside for simple convenience.

pramodattingal, your lack of fluency in the english language is no excuse for a lack of common sense, obviously its assembled before being slid down the pipe. 60° will likely be better in a well made charge. In your case I think the angle irrelevant as the precision of the charge is whats going to determine if it works or not, not the cone angle.

Quote:
how did you protect yourself from shrapnel


I'm not holding the camera. I never watch explosions without something between it and I. I'm about 100m away on the other side of that stump/rock in the pictures.
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[*] posted on 17-3-2005 at 11:55


You can see him duck down in the distance in the video of the second test. So there is a ditch, large rock and some distance between him and it.
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[*] posted on 5-4-2005 at 04:17
easy coppercones?


Although copper is one of the best liner materials, making a perfectly symmetrical liner out of coppersheet is very hard.
I tried so several times to make one out of multiple layers of 0.15mm sheet always resulting in a jet consisting out of 2 or more "fingers"
I never have this problem with 35 mm steel hemispheres made from.... coffeespoons! :D Always making a clean hole through 5 cm of mildsteel! for this I use 2 times diameter standoff with a NM based plastique...

Hopefully not pushing the discusion too much to the practical side, but could it be possible to make a good coppercone by winding and glueing 0.75mm-1mm copperwire over a 60 degree papercone?

Studies revealed that the liner collaps and penetration occur by hydrodynamic flow. So in my theory upon detonation the pieces of wire will collaps the normal way, plastisize together and form a normal coninuous jet.
Any thoughts?

[Edited on 5-4-2005 by nitro-genes]

[Edited on 5-4-2005 by nitro-genes]

[Edited on 5-4-2005 by nitro-genes]

[Edited on 5-4-2005 by nitro-genes]
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