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Author: Subject: Unconventional Shaped Charges
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[*] posted on 17-1-2015 at 13:38


These devices have been extensively tested by different groups, guaranteed, but probably not much at the scale we are working at. Finding reporting of these test results in the literature might be a challenge though.



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[*] posted on 18-1-2015 at 01:38
lead


In one patent, unfortunately I do not know the source, is center of the liner filled with lead. This method can readily be formed thick and heavy center. For better stability...LL

lead.jpg - 14kB
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[*] posted on 18-1-2015 at 03:06


Interesting idea, however it will increase the complexity of the liner. I'd suggest making a smaller dimple that can be filled with lead and sanded flat before inverting the liner.
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[*] posted on 18-1-2015 at 15:11


Keeping the Lead bonded to the Copper layer under the forces applied might be an issue?

Two layers of Copper @ 1/2 the desired thickness, very slightly different in curvature near center, such that they could be clamped into proper relationship, heated and a flux cored solder fed into the central void- Capilary action should take solder right to the outside edges, forming a solid unit




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[*] posted on 18-1-2015 at 19:08


Quote: Originally posted by Bert  
Keeping the Lead bonded to the Copper layer under the forces applied might be an issue?

Shouldn't be a problem, lead solders well to copper and is extremely ductile. Use a good flux or pre-tin the copper and you should be safe.
But building a more complex geometry by soldering/brazing sheats of Cu would also be an option, I agree.
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[*] posted on 19-1-2015 at 09:02
center lead


Produce lead center is very laborious. Nevertheless, the result is not good. Liner is uneven, not regular. Precision production (with lead) requires more precise instruments. Fulmen method is a good way to go. For further experiments (yet) will be used classic concave copper...:cool:...LL

lead center.jpg - 219kB
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[*] posted on 9-2-2015 at 07:24


There is a way for 20 minutes to produce a relatively precise cone for use SC...LL...:cool:
https://www.youtube.com/watch?v=s0vgSBIc2UY
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[*] posted on 9-2-2015 at 07:52


That's a nice low tech metal forming process- The results look good.

Did you measure thickness of finished cone? Thickness tapers from near apex of cone to outer edge?




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[*] posted on 9-2-2015 at 10:28
cone


The outer edges are thicker, thus no change, 1 mm thick. The top of the cone is copper certainly weaker, thinner. But the measurement is difficult. Estimating peak cone is about 0.5mm thick...:cool:...LL
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[*] posted on 9-2-2015 at 13:19


Thank you for the good video LL.

One question:
How important is it to solder the cone in place?
Does it improve performance or does it just help to keep the come in position while pressing the charge in there?
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[*] posted on 10-2-2015 at 00:16
SC


First question: Performance is about the same. The second question, yes. Solder holds exactly the shape of the edge of the cone. This is important for accurate beam Cu. Fill the charge is much easier. Energetic materials can be easily molded. This pressing operation is required short cone. It is better to use plastic hard cover. As for EFP devices...:cool:...LL

SC press.jpg - 306kB
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[*] posted on 10-2-2015 at 03:02
SC 22


For the following experiment is used edge with the solder, from video. For home exam I think it's good. Of course, it's not professional equipment. TeACP 15g @1,75..:cool:...LL

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[*] posted on 25-2-2015 at 08:57
Dual liner shaped charge


A patent for same:

https://docs.google.com/viewer?url=patentimages.storage.goog...

I came across a set of these liners in "trumpet" configuration, outer Aluminum and inner Copper. Has anyone experimented with this configuration?



image.jpg - 134kB




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[*] posted on 17-3-2015 at 01:12
Found something interesting today


While at work today i came across this little guy. since i work in the construction sector i have seen a few of these things laying around but never took any notice. until today when i picked on up to look at it, and it looks like it would make a great little liner. it is copper, symmetrical and is 0.5mm thick all the way. it took me a little to figure out what it may be from and i think i found out. since i was near to an aircon unit being installed where i picked it up i searched a bit about it and came up with this. its some sort of dust plug for the copper piping i think. i reckon a test is in order to see if it work as i think it may. it fits nicely into some 20mm Cu tube but i may bend out the flange to get a little more area in the dish and punch a point into the dead center.if so it may be possible to obtain more if you were to find airconditioner installation place and ask if you could have a few. if i see them again i will be collecting them. NP

iaircon tubeages.jpg - 7kB 1.JPG - 143kB 2.JPG - 146kB




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[*] posted on 17-3-2015 at 06:50
1/2" Steel Cone and 4g of ETN Plastique Penetrates 3/4" (ca. 19mm) of Plate Steel


A test was just performed with one of the 1/2"W X 7/16""H (~53 degree apex angle) UK steel cones that Markx introduced earlier in this thread. The steel plate was successfully penetrated, though a large carrot was left plugging the hole.

BTW, what I said back on page 38 of this thread, "I got a half order of the 1"W X 1"H (~53 degree apex angle) UK cones that Markx was using and the other half in 1"W X 1/2"H (~90 degree apex angle) US style cone studs", was wrong, the steel cones are actually, ca. 1/2"W by 7/16"H and 1/2"W by 1/4"H.

Energetic Material Specifics

Charge:
4g of plastique; 80% ETN/10% polybutene/10% mineral oil

Initiation:
0.4g of PETN, 0.1g LA, pinch of basic lead picrate, cannon fuse

The steel cone was only held in place by the adhesive forces between it and the plastic explosive it was pressed into. A bit of scrap wood, with a hole the diameter of the casing drilled into it, was used to provide the standoff (1.5CD).

Eighty grams of the recently made ETN (discussed in the NG thread) was used to make 100g of plastic explosive. The picture below shows 6.4g separated from the 100g, but because it would not fit into the casing only 4g of it was actually used. A carrot was formed and was left jammed into the top 1/3 to 1/2 of the hole height. On examining the bottom of the 3/4" steel plate and the piece of firewood below, it was clear the jet passed completely through however. A hole roughly 1/2" deep was blown into the piece of firewood below the steel target.



ETN Plastic Explosive 100g.jpg - 206kB Charge Bottom View.jpg - 162kB Charge in Place.jpg - 241kB
Top.jpg - 264kB Bottom.jpg - 240kB Plate Thickness.jpg - 180kB
Hole Underneith (1).jpg - 250kB Hole Underneith (2).jpg - 251kB



NeonPulse, those do look like they might make decent liners for EFPs.


[Edited on 17-3-2015 by Hennig Brand]




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[*] posted on 17-3-2015 at 07:44


Could you estimate the density of plastic?

We are looking at which of the smaller holes? There are several tests on this target, apparently.

[Edited on 17-3-2015 by Bert]




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[*] posted on 17-3-2015 at 08:03


The density of this type of plastique was around 1.43g/cc the couple of time I measured it in the past, but it can vary a bit. I could maybe measure some in a while and get back to you.

Ok, I just measured the density. The water displacement method was used to measure volume. A piece of the plastic explosive was carefully weighed, then the sample was placed into a graduated cylinder which contained enough water that when the plastic explosive was added it was not too far from full (graduated cylinders are more accurate the more close to being full they are in general).

Mass of Plastique: 11.35g
Volume before addition: 212.0mL
Volume after addition: 219.6mL
Volume of Plastique: 219.6mL - 212.0mL = 7.6mL

Density of plastique = 11.35g / 7.6mL = ca. 1.49 g/mL


Top Highlighted Hole.jpg - 178kB Bottom Highlighted Hole.jpg - 190kB



Found an interesting Doctoral thesis on shaped charge theory. In the near future I think I will have a closer look at it.


Attachment: Penetration of the Shaped Charge.pdf (4.3MB)
This file has been downloaded 377 times


Plastic Explosive Stability
I wonder if mineral oil helps stabilize the ETN the way that Vaseline stabilizes Cordite propellants.


[Edited on 17-3-2015 by Hennig Brand]




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[*] posted on 17-3-2015 at 11:01


Do you mean stabilize ETN against chemical degradation/deterioration, or stabilize as in render less susceptible to accidental detonation?

If you previously gave the composition of the plastic, perhaps you could provide a link to that- Certainly seems to have VOD & power suitable for the use.




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[*] posted on 17-3-2015 at 11:10


To act as a chemical stabilizer, making the explosive more storage stable. It does also desensitize the explosive to initiation a lot as well, but that was not what I was commenting on. The following was taken from the Naval Propellants page which has a pdf made of it in the propellants thread, "Mark I cordite consisted of 37% nitrocellulose (13.1% Nitrogen), 58% nitroglycerine and 5% petroleum jelly. This last ingredient had originally been used as a lubricant during the manufacturing process, but it was found that it also acted as a stabilizer as its unsaturated hydrocarbons counteracted the byproducts of the decomposition process."

I wonder if the Vaseline we buy at the drug store is the same as what they were using to make Cordite. Has it been purified and the unsaturated hydrocarbons been removed for the most part?

I just recently added the plastic explosive composition in the above description.


[Edited on 17-3-2015 by Hennig Brand]




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[*] posted on 18-3-2015 at 01:55


Can you give some details about your plastic explosive manufacturing process?

Do you make different fractions, or just use the recrystallized ETN? Rolling or kneading?

I’m just curios, because the PE above have very good properties for such a primitive binder.
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[*] posted on 18-3-2015 at 04:12


Hot water from the tap (ca. 50C) was used to make a warm water bath. The polybutene and mineral oil were added to a glass bowl and heated on the warm water bath and mixed until warm, soft and of much lower viscosity than when cold. The fine crystalline ETN was then added to the softened polybutene and mineral oil mixture and then mixed with a plastic spoon. The partially incorporated plastic explosive "dough" was then placed on a previously warmed (ca. 30-40C) glass cutting board and repeatedly rolled out with a smooth glass bottle or glass or non-stick rolling pin of some kind. A rubber spatula can be used to scrap the "dough" off of the glass cutting board and off of the rolling pin when repeatedly rolling out the "dough". The material may also be placed in some waxed paper and kneaded by hand through the waxed paper, which I often do at the end of the kneading process.



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[*] posted on 18-3-2015 at 09:50


Nicely done! Although you might want to try a bigger standoff with these small cones....I found that 3-3,5CD gives the best result in terms of clean penetration. With smaller standoffs I had a very similar picture with the carrot getting stuck in the target, but the jet passing cleanly through. I guess with small charges and a 1,5CD standoff the cone has not enough time to fully form into a "spearhead", the edges hit the target on a wide area and seem to break the impulse.



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[*] posted on 18-3-2015 at 13:54


Thanks, yeah, I was thinking that too the more I looked at the images above. However, I only used 1.5CD for the last test, with a 3/8" steel target, and there was a nice clean hole, but in that case the cone was anchored (sitting on a lip of aluminum left in the casing when it was bored out on the lathe) and this time the cone was not anchored at all. I will increase the standoff, for the next test, which should help.



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[*] posted on 19-3-2015 at 11:25


Time for waveshapers :D



WP_20150319_002.jpg - 1.4MB WP_20150319_001.jpg - 1.3MB WP_20150319_003.jpg - 1.4MB WP_20150319_008.jpg - 1.2MB WP_20150319_009.jpg - 1.3MB WP_20150319_010.jpg - 1.1MB WP_20150319_011.jpg - 1.1MB WP_20150319_012.jpg - 1.2MB


I think NitroGenes already tested some configuration of waveshapers with quite a success on this thread....I'll try to meet the challenge tomorrow ;)

The power source ( PETN with 10% by mass 5/2 mix of polybutene and castor oil:

WP_20150319_013.jpg - 1.2MB

[Edited on 19-3-2015 by markx]




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[*] posted on 19-3-2015 at 16:24


Looking forward to your test and to learn a little bit about wave shaping. Nice neat assembly.



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