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Author: Subject: Unconventional Shaped Charges
markx
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[*] posted on 20-3-2015 at 06:17


Iäm planning on testing 2 charges of 7g capacity each on a 60mm thick solid steel block with 20mm standoff built into the device.

Charge I : with just the cone stud liner and 7g propellant pressed behind it.

Charge II: with the cone waveshaper placed in an inverted position behind the liner (forming a X geometry if viewed from side) and 7g propellant pressed all around the configuration.

Loading the cases:

WP_20150320_002.jpg - 1.4MB WP_20150320_003.jpg - 1.4MB WP_20150320_004.jpg - 1.3MB WP_20150320_008.jpg - 1.4MB WP_20150320_011.jpg - 1.3MB WP_20150320_012.jpg - 1.4MB WP_20150320_013.jpg - 1.3MB


I actually planned on 3 charges with 5g capacity (control, x configuration and shallow cone configuration), but 5g of propellant would not cover the x configuration. Hence I had to increace the loads to 7g and drop one of the configurations (the shallow cone one). The woes of rationed propellant amounts.... :P

[Edited on 20-3-2015 by markx]




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[*] posted on 20-3-2015 at 07:47


Markx, I though you would probably try penetrating a 1" plate or so, but it looks like you are really going for it. :cool:

Looks like you have a good technique for getting the cone well centered and aligned with the casing. I think improper centering and alignment has been by far my biggest problem in the past. The last test I did the cone was brought right out flush with the bottom edge of the casing so it was very easy to center (visually) and align by simply pressing the casing against a flat surface (assuming the casing end is cut perpendicular to the casing sidewall). Your method makes a more secure charge however. I bet I could just add a threaded, or other form of attachment (adhesive?), end ring to the charge casing with lip which could be installed after the liner was properly centered and aligned with the casing; the end ring would ensure that the cone stayed in position even if the charge was roughly handled.




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[*] posted on 20-3-2015 at 08:35


I do not hope to penetrate that huge hunk of steel with these small charges, but the objective is rather to compare the effects of the waveshaper vs control configuration. With this huge metal piece I trust that both jets are absorbed and I can measure the maximum penetration depths.



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[*] posted on 20-3-2015 at 10:07


markx, what kind of liner do use with these forms and how does the forming process work?
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[*] posted on 20-3-2015 at 13:11


Well....that was not really what can be called a success, although comparative effects are quite obvious...

"Charge II" with the waveshaper at 2,4CD standoff (30mm):

WP_20150320_015.jpg - 1.3MB WP_20150320_017.jpg - 1.4MB

The crater closer to the edge is the one with the waveshaper, the one further from the block edge is the control without any waveshaper in the design. Both were 7g capacity and at the same 2,4CD standoff. Both performed very unsatisfactory in terms of penetration depth.

WP_20150320_018.jpg - 1.4MB

Cut open the "charge II" channel and measured the depth...only a meager 17mm:

WP_20150320_019.jpg - 1.3MB WP_20150320_020.jpg - 1.3MB

I did not grind open the "charge I" crater but mesured the depth with a thin wire and it was more or less the same 15-17mm....

I've had 15mm with exactly half the charge capacity under similar conditions and clean entry channels at 40mm standoff.
Bad cones? they were from the same batch that I've used for all of my experiments so far. Unfortunate misalignment of both cones? Very possible scenario. Tougher steel target? Perhaps, although it seemed pretty mild when touched with a file. Lower detonation speed due to using castor oil insted of methyl riccinoleate as plasticiser? Possible, but not very likely...
The charges portrayed here were pressed under arbor style press, all the others before I've compacted by hand.
I'm at a bit of a loss here to be honest...

Ok...all that aside, when we look at the entry points it is pretty much clear that the waveshaper design has much better focus in terms of jet formation. It shows a lot of promise if the kinks are worked out :) The control charge on the other hand is utterly out of focus and the whole crater is a total mess...this is THE most unsuccesful shot of my entire SC career :D







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[*] posted on 20-3-2015 at 13:21


Quote: Originally posted by Gargamel  
markx, what kind of liner do use with these forms and how does the forming process work?


By forming process do you mean the forming of the liners? They are prefabricated "UK77 cone studs" off the ebay (for the "punk metal" crowd I presume :) )
They are composed of a soft ferric alloy that is magnetic and surface treated to give a brass like look...




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[*] posted on 20-3-2015 at 14:10


Shaped charges are quite delicate, and logic suggests that small devices should be most sensitive. It's part of the reason I've stopped experimenting, every study ends with the question of what accuracy one should strive for and how to accomplish this. This combined with the greed of wanting the best performance I can possibly prevents me from getting anything real done. There is also the question of statistics, without a model based on quantifiable data one test can only tell you so much. I know I'm overly fuzzy about this, but that's the way it is.
But I also feel the engineering part of me looking for a fun challenge, and revisiting the drawing experiments does have it's appeal. I now have a heat treating furnace, and I have always loved making permanent tooling.




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[*] posted on 20-3-2015 at 14:45


Quote: Originally posted by Fulmen  
Shaped charges are quite delicate, and logic suggests that small devices should be most sensitive. It's part of the reason I've stopped experimenting, every study ends with the question of what accuracy one should strive for and how to accomplish this. This combined with the greed of wanting the best performance I can possibly prevents me from getting anything real done. There is also the question of statistics, without a model based on quantifiable data one test can only tell you so much. I know I'm overly fuzzy about this, but that's the way it is.
But I also feel the engineering part of me looking for a fun challenge, and revisiting the drawing experiments does have it's appeal. I now have a heat treating furnace, and I have always loved making permanent tooling.


True that...SC-s are a finnicky business, but they fascinate me, nevermind the complications. I guess everyone sometimes picks a topic that may engulf our mind in intricate and seeminlgy hopeless complications, but if our facination drives us to act then we do ever so often succeed...at least partly :)

About the size vs effect of imperfections on a device....i do not know if it is completely accurate to assume that smaller devices (within reasonable scope) are more prone to failures due to imperfections. I tend to think about it this way:
a) smaller devices are way harder to build precicely and without imperfections
b) but the timeframe of a small device from acutation to completion is also shorter. Hence the forces at play have less time to pronounciate the effects of these imperfections.

From that reasoning I would assume that the most troublesome combination would be a device of mediocre scale that meets the worst of both worlds....it is still hard to eliminate the imperfections, yet the timeframe is long enough to pronounciate the effects of these errors. Perhaps my reasoning is not correct...but the devices that I have constructed have been way less than precise. Hand cut and assembled , sometimes visually crooked, yet have performed very reasonably and ever so often even exceeded all my expectations. The first SC that I slapped together was an abomination in terms of precision and I thought to myself "F*** me if that thing is going to work in any way!" but after seeing the jet crater gaping through an 8mm steel plate I was in awe..."what the heck happened and can this be replicated???"




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[*] posted on 20-3-2015 at 15:07


Ideally time shouldn't factor in at all. The principal problem as I see it is the limitations in accuracy both during manufacture and assembly. And not only dimensionally (as in shape, thickness or angle of liner) but also variations in density in the explosive or liner, grain structure and even accumulated stresses within the liner. At some level everything factors in. But understanding exactly how these factors scale in respect to each others isn't something learned over the weekend.





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[*] posted on 20-3-2015 at 15:44


Quote: Originally posted by Fulmen  
Ideally time shouldn't factor in at all. The principal problem as I see it is the limitations in accuracy both during manufacture and assembly. And not only dimensionally (as in shape, thickness or angle of liner) but also variations in density in the explosive or liner, grain structure and even accumulated stresses within the liner. At some level everything factors in. But understanding exactly how these factors scale in respect to each others isn't something learned over the weekend.



And there are at least 25 more factors besides all of the ones that we can conceive and identify in our minds :)
And it just drives me to explore them, despite having embraced my inability to ever fully understand the "Great design". I mean even the modest "tree body problem" has eluded the scopes of our mighty art for decribing the physical reality with anlytical precicion...the one called mathematics ;)




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[*] posted on 20-3-2015 at 17:40



I think for the same accuracies percentage error would get larger as charge size got smaller. It seems logical to me that smaller charges would be more challenging to make work as consistently for this reason. Looking back through this thread there is a wealth of information. It is humbling to see all the good work that was done by some of the forum members in this area. I don't think we can figure it all out in a weekend ourselves, but this thread has an accumulation of likely hundreds of weekends of research and experimentation, done by a large group of experimenters, all with slightly different perspectives. I am just starting to read back through this thread now. There are no doubt a great deal of variables involved with shaped charge performance, but I think there are only a handful of make or break type variables and then many other less significant variables that can be later played with to wring out more performance. Liner centering and alignment, liner and casing symmetry, liner and casing thickness uniformity, explosive density uniformity, explosive composition homogeneity & no voids, properly positioned initiator. From what I have read and what I have experienced these are the main make or break variables (I may have missed some). Failing to reasonably accurately control the make or break variables can result in complete charge failure, not just a little less penetration. I think using the wealth of knowledge available just in this thread alone and our own experience it is very possible to identify these key variables and then move on from there and wring out more performance by playing with the fine points. The extreme complexity likely arises when trying to play with a large number of these fine points simultaneously in order to wring out as much performance as possible from a given shaped charge. I think it is easily possible for an experimenter to get to the point that they can make consistently reliable shaped charges of very serviceable performance. Getting cutting edge performance is something else entirely.




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[*] posted on 20-3-2015 at 23:38


Quote: Originally posted by markx  
Well....that was not really what can be called a success, although comparative effects are quite obvious...


Hi

At first, nice post and all:)

But...making a 7g HE-SC with a waveshaper doesnt seem to be a good idea for me cause of the critical diametre...even with easy to ignite material it is very hard to make it perfectly work as far as i know/guess

I wouldnt go for waveshapers at a CD under 4cm...
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[*] posted on 21-3-2015 at 04:35


Quote: Originally posted by VladimirLem  
Quote: Originally posted by markx  
Well....that was not really what can be called a success, although comparative effects are quite obvious...


Hi

At first, nice post and all:)

But...making a 7g HE-SC with a waveshaper doesnt seem to be a good idea for me cause of the critical diametre...even with easy to ignite material it is very hard to make it perfectly work as far as i know/guess

I wouldnt go for waveshapers at a CD under 4cm...


Most of the enterprises that we undertake on this section of the board are several subway stops away from being a "good idea" :D
But they are just too much fun to make us stop....and I guess being able to find joy in the things we do is the most important aspect :)




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[*] posted on 21-3-2015 at 07:28
Holy explosive


Beauty is in explosives. Just as in the equation E = m.c2. As in the Sun. This is our most powerful explosive. He works for billions of years. Gives energy, gives life. The blast created life. Our bodies come from supernova. From the most powerful explosions in the Universe. Whole Earth comes from the supernova. The whole universe comes from the Big Bang. Even time and space comes from the explosion. Absolutely everything comes from the explosion. Examination of explosives is the way to God's creation. God is greatest pyrotechnics expert of all time. He could detonate time and space. And we are his disciples. Says the holy Isaiah to his disciples, and everyone watching the stars.

[Edited on 21-3-2015 by Laboratory of Liptakov]
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[*] posted on 21-3-2015 at 11:09


I feel very spiritual right now, and have even more love for these beautiful explosives. :)


[Edited on 21-3-2015 by Hennig Brand]




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[*] posted on 21-3-2015 at 13:04


Quote: Originally posted by Laboratory of Liptakov  
Beauty is in explosives. Just as in the equation E = m.c2. As in the Sun. This is our most powerful explosive. He works for billions of years. Gives energy, gives life. The blast created life. Our bodies come from supernova. From the most powerful explosions in the Universe. Whole Earth comes from the supernova. The whole universe comes from the Big Bang. Even time and space comes from the explosion. Absolutely everything comes from the explosion. Examination of explosives is the way to God's creation. God is greatest pyrotechnics expert of all time. He could detonate time and space. And we are his disciples. Says the holy Isaiah to his disciples, and everyone watching the stars.

[Edited on 21-3-2015 by Laboratory of Liptakov]


Every now and then, a real gem of a statement comes along, well said :cool:




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[*] posted on 21-3-2015 at 13:20
5g of ETN Putty Explosive and 1/2" Steel Liner Pierce 28.6mm of Steel Plate


Just performed a very successful test with one of these little 1/2" steel cones. The picture below shows 4g of plastique but with additional casing room left another gram was added for a total of 5g. The plastic explosive used was from the same batch as was used in the last test (80% ETN). The target was one 3/4" plate and one 3/8" plate, one stacked on top of the other. Standoff used was 2.5CD. The liner was not secured but simply held in place once again by the adhesive forces between it and the plastic explosive.

The jet did completely penetrate both pieces of steel, but just barely. A little flap of steel was still left attached on the bottom piece of steel though a hole was blown clean through on one side of it. The hole was so small by the bottom of the last piece that the diameter was even smaller than a pin. The carrot was once again driven into the top plate plugging the entry hole. The tops of the plates are shown in the first picture and the bottoms in the second. Another picture shows the bottom of the bottom plate where it can be seen that the jet escaped but left a little flap of steel still attached.

Explosive: 5g of 80% ETN Plastique
Penetration: 1.125 inches or ca. 2.86cm (28.6mm)

1.jpg - 243kB 2.jpg - 244kB 3.jpg - 240kB Tops.jpg - 229kB Bottoms.jpg - 221kB 6.jpg - 173kB 7.jpg - 186kB 8.jpg - 184kB


[Edited on 21-3-2015 by Hennig Brand]




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[*] posted on 22-3-2015 at 00:26


Well, liner diameter 12,5 mm trough 3 cm steel and 5g brisant only, this is good result. A good disciple of God, I think...:cool:....Isaiah says of the mountain Liptakov
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[*] posted on 22-3-2015 at 05:12


Thanks, I think this is the first time I have been called a disciple before. Makes me feel important. :)
I think that thick carrot slamming into the top of the target may be at least partly because the cone wasn't anchored, but I have only done two tests with an unanchored cone so I am not completely sure. It is interesting that even at a 2.5CD standoff the result was about the same as with 1.5CD standoff with regards to the large carrot being fused to the top of the steel target and plugging the entry hole.




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[*] posted on 22-3-2015 at 08:22


The scene with the carrot is really interesting...I've had similar, but not quite that epic appearances. And these happened with really small charges below 3g capacity with the carrot mostly splattered into the target like an efp, yet the jet itself passed on strong. Over 5g charges have always managed to disintegrate the liner or fuse it to such a degree that it is no longer distinguishable from the target. I did manage to catch one tough, on the 15mm target test. It was a really well formed specimen that I preserved with great care...a literal carrot and it stuck by a thread on the exiting verge of the crater. I could remove it from the target with just my bare fingers :D


For entertainment...a peculiar failure from one of my very fist attempts on SC with a ETN based plastique:



20130930_191503.jpg - 858kB 20131023_182431.jpg - 979kB 20131023_182821.jpg - 1MB 20131023_183038.jpg - 1.3MB 20131023_183514.jpg - 1.9MB

Incomplete initiation....but it left a really cool mark on the steel :D

[Edited on 22-3-2015 by markx]




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[*] posted on 22-3-2015 at 13:07


High explosive stamping? No ink required. :D
That is interesting to look at. Gave the steel plate a good slap anyway.

Do you have an idea why it didn't shoot properly? What percentage ETN was it?


[Edited on 23-3-2015 by Hennig Brand]




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[*] posted on 22-3-2015 at 23:25


Quote: Originally posted by Hennig Brand  
High explosive stamping? No ink required. :D
That is interesting to look at. Gave the steel plate a good slap anyway.

Do you have an idea why it didn't shoot properly? What percentage ETN was it?


[Edited on 23-3-2015 by Hennig Brand]


I really overdid it with the inerts that time. I was trying to get a very good plasticity of the explosive (30-35% inerts if I remember correctly). It was excellently pliable, just like modelling clay or placticine....didn't shoot too good though :P




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[*] posted on 24-3-2015 at 01:31
hole


Well, finally! Nice hole. When he wants, so it goes. This second attempt is much better. Through the hole is. And that's the main thing...:cool:...LL

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[*] posted on 24-3-2015 at 13:57


You know, I remember having a similar experience several years ago. I wasn't doing anything sophisticated like building a shaped charge, I was just going out to "communicate" with the people on the other side of the river setting of commercial fireworks (aerial shells). I remember taking 15-20g of ETN plastique with Pib not polybutene, IIRC, and adding aluminum powder for a more vicious air blast and flash. Now, if you are into a good explosion aluminized explosives are awesome. It is really impressive how even 5% of fine flake aluminum powder can often greatly increase the perceived violence of a detonation. A dynamite with 40% NG, 10-15% fine flake aluminum and the balance inorganic nitrate makes a scary air blast. Anyway, to make a long story short, the charge ended up being only about 65-70 percent ETN and with all the extra material added it failed to detonate using a detonator that would have easily ensured detonation with 20% inerts & 80% ETN.

LL, I hope this isn't how you have been making the holes in your steel targets all along. ;):D


[Edited on 25-3-2015 by Hennig Brand]




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[*] posted on 24-3-2015 at 22:51


But of course. I never make a gram of explosives. It's all photomontage. Manufacture explosives is prohibited. Produce virtual reality is permitted without restriction. Whenever I can prove it....:D....LL
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