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Author: Subject: Unconventional Shaped Charges
ZoSo357
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[*] posted on 22-1-2006 at 08:15


I was just cutting apart a CO2 cannister to see how thick the metal wall is, and it seems like it may work, the wall is pretty well dead on 2 mm, so this seems like a good liner, but also, when i cut it off just from the tip, I noticed the tip may make a good cone. The cone almost fits into a half inch copper pipe, so this may make a good charge for something slightly bigger than the bullet jacket cones. Also you could cut off just the "butt" of the CO2 cannister and get a hemispherical charge without using the rest of the cannister. I don't have a camera right now to take a picture of this. sorry.

EDIT: Fulmen, I was talking to a friend over at APC forum about using test tubes, and you can usually buy culture tubes by the hundreads for really good prices, usually about 5 cents a tube.

[Edited on 22-1-2006 by ZoSo357]




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Fulmen
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[*] posted on 22-1-2006 at 14:01


To be honest I'm having some doubts about the CO2-cannister. Going from a sphere to a cylinder means that there will be an increasing jet velocity during formation, and that just might cause problems. Think about it, the first part of the jet from the hemisphere vill be a fairly high mass, low velocity jet, while the cylinder should produce a high velocity, low mass jet. What will happen when the latter jet catches up with the first one? My fear is that the collision will simply disperse the jet causing havoc in the bottom part of the tube.
This could account for the "head" in these pictures: http://www.llnl.gov/str/Baum.html

For a simple hemispherical charge this might not be a problem, but inside a long cylinder I'm not so sure.

This is also supported by the fact that the prefered shape today seems to be a trumpet shape. This shape has a increasing angle througout it's length, resulting in a decreasing velocity profile.

ZoSo, I like your idea. I suppose both ends could be used for smaller charges, especially the tip since it has an almost perfect trumpet shape.

As for the sylindrical liners, I still belive in them:D
Remember that the trumpet liners start out as an open cylinder, why would they choose this design if it didn't work?

Test tubes is a nifty idea, I't got me thinking of using Erlendmeyer-flasks. Guess I'll have to look around to see if I have any glassware that can be sacrified for science.

[Edited on 22-1-2006 by Fulmen]

[Edited on 22-1-2006 by Fulmen]
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oneup
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[*] posted on 23-1-2006 at 05:58


Axt, you're using an explosive mixture that contains strong acids, and you're bringing it in contact with an aluminum liner. doesn't it eat through?



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Coolio
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[*] posted on 23-1-2006 at 07:25


Alu is resistant against HNO3 ;)
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[*] posted on 23-1-2006 at 08:19


but not against h2so4



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12AX7
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[*] posted on 23-1-2006 at 13:22


Um, I've distilled NH4NO3 + H2SO4 with aluminum before. As long as there is very little moisture present, it does not get attacked significantly.

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[*] posted on 24-1-2006 at 01:29


hmmm aluminum itselve might be resisitant. but i'm sure aluminum OXIDE is not. all oxides are basic, and are thus atacked by strong acids (correct me if i'm wrong) and becouse aluminium always has an oxide layer a small ammount the aluminum sulfate/nitrate will contaminate your acid.



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[*] posted on 24-1-2006 at 02:22


So what? 1% contamination in a shaped charge filling would not worry me in the least. If it forms a few bubbles, so much the better (detonation transfer).

Plus, does saphire really dissolve in sulfuric?
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ZoSo357
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[*] posted on 24-1-2006 at 03:32


I found this by searching google:

http://www.monocrystal.com/products/s-features

And if you can't access that link:


Sapphire features


Benefits

Withstands high temperatures


Will not melt until 2050°. Maintains purity
in high temperature environments

Hard and strong


* High processing survival rate
* Scratch resistant to most materials
* Withstands high pressure
* Excellent wear surface

Chemically inert, insoluble
in most common industrial
solutions and corrosion resistant
(i.e. hydrofluoric, sulfuric
and hydrochloric acid)


* Can be used in harsh environments
* Can be easily cleaned
* Longer life
* Free of contaminants
* Sapphire life is up to five times that
of quartz in some environments

Transmits ultraviolet, visible,
infrared and microwaves


Excellent waveguide performance at 0.25 - 4 microns
Durable and reliable IR laser transmission

Has excellent electrical properties


Low dielectric constant

High thermal conductivity


Provides rapid heating and cooling capability




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Coolio
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[*] posted on 24-1-2006 at 09:31


A few weeks ago I tested a linear shaped charge with ANNMAL 94:25:4 :o :P

I know the idea is bullshit, but I don`t matter.....

Here is the vid:

http://rapidshare.de/files/11736125/LSC.mpg.html
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Coolio
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[*] posted on 26-1-2006 at 10:56


hm nobody is interested in my video...


question: Is it a mistake to make a standoff of 15mm by a cylindrical shaped charge ?
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rot
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[*] posted on 26-1-2006 at 13:48


12AX7, you're using Nitromethane/Nitric acid 70%. doesn't this 70% HNO3 contain way too much water?
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12AX7
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[*] posted on 26-1-2006 at 14:08


Quote:
Originally posted by rot
12AX7, you're using Nitromethane/Nitric acid 70%. doesn't this 70% HNO3 contain way too much water?


Um? I haven't produced NM yet, and if you're speaking of an explosive composition, I haven't done any experimentation with that either. You must be referring to someone else.

Tim




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Boomer
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[*] posted on 27-1-2006 at 00:22


He uses distilled (99%) nitric, and he uses 70% of it with 30% NM.
That is like 100% pure HCl (i.e. no soaps etc) of 30% concentration (rest water).
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[*] posted on 27-1-2006 at 07:50


70% nitric acid with 30% NM would have a far to positive oxygen ballance...70% nitric acid with 30% nitrobenzene is maybe the composition you are confused with.

I believe the original composition of this NM sprengel type explosive was 70% NM with 30% nitric acid (99%.) There is some information about it in PATR. But as can be seen from Axt's movies, apparently 99% nitric acid can be substituted with 70% in the same quantity...
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[*] posted on 27-1-2006 at 09:49


Its 70% HNO3 straight out of the bottle. So yes it did contain a bit less then 10% water. Obviously your better off using distilled nitric but if your lazy you dont have to, its plenty sensitive enough, even when containing a good portion of water.

For the record, with distilled nitric the best density/OB is about 62:38 NM/HNO3. Can you give that PATR reference nitro-genes, ive never seen it, I just used that ratio because it sounded good :)

Anyway ... back to shaped charges ay. :(
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Axt
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[*] posted on 28-1-2006 at 04:19


Below is 80% copper, 20% polyester cast in the funnels shown on page 6. 80:20 was pourable. Cones ended up a bit heavy duty. The taper on the plastic funnel stems didn't allow the wall thickness to be reduced further.

I broke the stems off the glass funnels trying to get it out, this was likely caused by slight defects in the glass as it wasn't completely smooth, had a bit of a "ripple" in it.

The set cone come out of the plastic funnels easily. I used some spray on wax stuff to prevent it sticking.

<center><img src="http://www.sciencemadness.org/scipics/axt/resin-liners.jpg"></center>

[Edited on 28-1-2006 by Axt]
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nitro-genes
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[*] posted on 29-1-2006 at 13:33


They certainly look quite promising! Hopefully you are going to try them out soon...:D What is your estimation of the density of the material? Is it still realy dense like copper alone?
They might prove to be a little too thick indeed :(... I've read that aproximately 3% of the charge diameter should be the thickness of the liner for soft copper. My own attempts with steel liners of 2,5 mm thickness and 5 cm diameter resulted in a rather shallow penetration hole almost completely filled with the steel from the liner. :)

As for the reference in PATR about NM/Nitric acid:

This is what I was able to find again. I am sure I have seen more information about it elseware too when I was considering to try this explosive for myself....:( (Which I never did because of the arrival of a new 2,5 kilo's of PE ;))

EXPLOSIVES NONMILITARY (COMMERCIAL)
(Papers and Reports Listed in Chronological
Order)

R.W. Lawrence, CanadP 417844 (1944) 8~
CA 38, 1644 (1944) (Expl contg concd nitric
acid and nitroparaffin, such as nitric acid
15-63%, nitromethane 85-37%)

[Edited on 29-1-2006 by nitro-genes]
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[*] posted on 30-1-2006 at 15:08


No, the density is only about half that of copper, even though it started out 80% Cu by weight, the low density of the binder really cuts it down. So I really dont know whats going to happen, only one way to find out. The smaller liner (33mm) still weighs 17g.

I did find reference to open apexed conical liners, saying that its "desirable" to have an opening at the apex 1/10th the cone diametre. Not stated what they mean by desirable, but the previous abstract I posted relating to open apexed hemispheres mentions faster jet velocities. So I'll try to leave it as is.

Below is the .357 fired in same fashion as .45 on page 5, 3mm plates clamped together and fired through the side. Penetration was just short of an inch, though with a much thinner jet which for most of its length staying within the boundary of the 3mm steel, bulging it out as it passed through. The .357 is a nicer shape then the .45, which is quite flat on top.

<center><img src="http://www.sciencemadness.org/scipics/axt/357-peno.jpg"></center>

[Edited on 2-2-2008 by Axt]
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Fulmen
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[*] posted on 31-1-2006 at 09:24


Nicely done Axt. Impressive performance, although it is obvious they could do with a increased charce diameter. Personally I'm going to put the cylindrical charge on hold for now, as I stumbled over a 54mm stainless hemisphere in the form of a ladle. It's perfectly smooth and appr. 0,5mm thick, should do for an impressive blast. The only question is the subcalibration ratio (charge diameter to liner), is there a good rule-of-thumb to follow?
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[*] posted on 31-1-2006 at 12:08


This concept of copper powder bound by polyester is quite appealing, but what if you would mix this copper powder with the same plasticizer you would use for making C4 or semtex? The result would be a very high density 90+% copperclay which is still easy to mold. The same prinicple is used with the new "silver art clay" When baked, the organic binders "bake out" and a 99,9% metallic material remains with minimal shrinkage.

--> http://www.artclayworld.com/artclaytosilver.html

I don't see any trouble using copper powder as a subsitute for silver powder only that the melting temperature is slightly higher for copper... Forming a liner out of this clay would be more easy than pouring one I think.

First roll out the clay to a determined thickness by rolling over two plates of the desired liner thickness with the clay in between. Then cut out a circle, and lay it over a hemispherical mold for a hemispherical liner or use half the circle to form a cone. Put in a high temperature oven or use a blowtorch to heat and the liners should be ready...

As with all ideas this might sound simpler than it realy is...But I realy think when you would be able to make a good moldable clay from copper powder it would be worth the effort...

I know I'm not supposed to ask, but did you make this copper powder yourself Axt? I did a search on the internet, but couldn't find any OTC supplier of copper powder. (that delivers to individuals that is)

[Edited on 1-2-2006 by nitro-genes]
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Axt
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[*] posted on 31-1-2006 at 20:51


Quote:
Originally posted by Fulmen
Nicely done Axt. Impressive performance, although it is obvious they could do with a increased charge diameter.


I think you'll see more efficiency the larger the diametre, but less efficiency for explosive weight. Above was only 1.2g penetrating just shy of 1", thats the equivalent of a 200g SC penetrating over 4m of steel. You wont get that from larger charges, but you may penetrate more "LD's".

Quote:
The only question is the subcalibration ratio (charge diameter to liner), is there a good rule-of-thumb to follow?


Yes, most hemi sc drawings I've seen do have a larger diametre explosive loading then the liner. Right now I'm looking at a SC designed for the Jap kamakasi's in WWII. It had a 1.6m wall and 1.4m hemi liner (with 32cm hole in apex). May give you something to go off.

Interesting Idea nitro-genes, but a lot of question marks above it, like using other metals and polymers to create the same effect may not work at all.

The copper powder was bought, and sold for the purpose of resin filler. There is a topic here regarding precipitated Cu by reducing copper sulphate with vitamin C, may be an alternative, check it out.

[Edited on 1-2-2006 by Axt]
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[*] posted on 1-2-2006 at 04:59


1.6m? Damn! Anyway, I ended up with the exact same ratio for my charge, since the can intended for the sylindrical charge was the most practical container i had around. Not sure how much effect kinepak will give at the edge, but it should be impressive nevertheless. There is only 4-5mm space at the end, hardly enough to sustain detonation, but then again the detonation waves will continue some distance anyway, right?

I agree that the gram-equivalent performance for the jacket-charges is quite impressive, I guess it's just a question of what is more valuable, the liner or the explosive. Next time, try to cut the jacket at the crimp-groove, I have a sneeky suspicion that the sylindrical section might disturb the collapse somewhat.

On that note, how does hemis and cones compere to each other? Are the cones more efficient no matter what, or do they just perform better for a given diameter (usually a limitation in ammunition)? Looking at xrays of collapsing liners it seems to me that the hemis deliver more mass to the target, but I'm not sure how the tradeoff between mass and velocity affects performance.

BTW, have you tried EFP's? Sounds like a fun alternative to regular target shooting ;)
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[*] posted on 1-2-2006 at 05:57


If we are getting into test tubes, why not use the bottom from a centrifuce tube? http://www.biomedicalmarketing.com/Simport/CultureTubes/T420...
These on the picture afe plastic, but this is the picture with the most promising angle on the bottom.
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[*] posted on 1-2-2006 at 10:22


Perhaps because they may not make them in glass? The only ones that I have seen have been plastic.

The bullet-jacket charges are very appealing, as I am working on some high-preformance explosive cast mixtures and plastiques. I belive for charges that small, it may simply be best to stick with single types of explosives though.

I am developing a ETN/TNP cast comp that may be interesting as a shaped charge explosive, though it needs to be kept very dry. It has some interesting properties...




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