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Author: Subject: Unconventional Shaped Charges
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[*] posted on 5-1-2015 at 11:45
packaging


Well! It looks good. I see that a lot of copper is annealed. That is good. I made a few more unsuccessful attempts. Attention. The packaging is very important. It must be hard, preferably steel wall at least 2 mm thick. It is minimum. If the packaging is soft (plastic only) or weak (only Cu clutch 1mm), EFP does not work good. Use soft or weak packaging waste EM...:cool:...LL
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[*] posted on 5-1-2015 at 14:47


Thanks, good to know about the casing requirements. I might try one more test before I go for stronger confinement anyway though.

What you are looking at in my last post is an old piece of copper plumbing pipe that was cut down the middle, lengthwise, and folded out. The black is black copper oxide. Annealing probably would be a good idea though.




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[*] posted on 8-1-2015 at 05:31


LL, are you anchoring the steel target? I have been just standing the target up and using a small spring clamp to steady it. Trying to decide if anchoring the steel plate/target better would make much difference.

The following snip-it was taken from, "History of the Shaped Charge Effect - The First 100 Years", by Donald R. Kennedy. I thought it was kind of interesting.

History of Explosively Formed Projectile.jpg - 440kB




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[*] posted on 8-1-2015 at 07:55
gold sands


Henning, I know how attached the target. It is in the figures, the photo. If the target is large and heavy, so it's unimportant. The target may be in the air or sand. This does not affect the result. If so, I guess only difference is 5%. Maximum 10% of the whole assembly sand versus air. The sand will always be a little better results. And most importantly, it's safer. In particular, if the device is made of steel...:cool:...LL
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[*] posted on 8-1-2015 at 08:24


I didn't try to work it out, at least not yet, but that is what I figured too. The diameter of the projectile is small and moving at very high velocity and the target is relatively heavy (a lot of inertia).


Success with Conical (Munroe Effect) Shaped Charge

I bought some of the steel cones that Markx discussed earlier in this thread here:
http://www.sciencemadness.org/talk/viewthread.php?tid=10575&...

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. I used one of the 1" X 1/2" cones for my first test. An aluminum tube was bored out on the lathe so that it had an inside diameter slightly larger than the cone with a lip left for the cone to sit on. A section of hardwood dowel was turned down, so that it would fit the aluminum casing snugly. The wooden dowel section was also bored so that one end could accept safety fuse and the other end could have 0.15g LA, and 0.5g of PETN pressed in. Plastic explosive was used (3g of 80% ETN/10% polybutene/10% mineral oil). The PETN was in direct contact with the plastic explosive when the wooden bushing was put in place. Standoff used was 1.5 CD (charge diameter). Cone/liner diameter was ca. 1/2" (12.7mm). Charge diameter was ca. 15mm.

The charge easily penetrated the 3/8" (ca. 9.5mm) steel plate. Hole diameter was ca. 4mm at entry and ca. 3.4mm at exit. I know Markx has already been here with a similar type of charge, but it really is impressive how well these work. I feel I should have tried a thicker steel target, especially since I see looking back that Markx penetrated 15mm of steel with the more acute angled cones of the same type.

I don't have a lot of pictures because I forgot my phone when leaving for the test site. I did take one before assembling the charge and a couple of the target once I returned home.



Components.jpg - 125kB

Witness Plate Top View.jpg - 432kB Witness Plate Bottom View.jpg - 373kB


[Edited on 9-1-2015 by Hennig Brand]




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[*] posted on 8-1-2015 at 12:34


Do you have an opinion on EFPs based on rather slow explosives? Like AN or even Chlorate binaries?

When I tested such charges on metal witnes plates I found that often holes with charge diameter where punched, and the loose material hit the ground with a lot of penetration power.

But the standoff was only 30mm or so. I wonder what would happen with the right standoff?


2500 or maybe 3000m per second is not hypervelocity, but maybe there will still be some kind of flowing or maybe forging of the metal into a "penetrating something"?
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[*] posted on 8-1-2015 at 12:40


I don't have a lot of experience with it, but the literature indicates that those low velocity type explosives don't perform well in shaped charge applications.



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[*] posted on 8-1-2015 at 14:38
cone 84


For deep penetration cumulative effect better is VoD + 6000 m/s. For EFP + 7000 m/s. (for quality efects). Use of plastic / copper / for the SC device. Construction steel 30mm / 1.18 inch. Inclined cone a few degrees. This is the error impact on the TOP...:cool:...LL

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[*] posted on 8-1-2015 at 14:55


That was a nice result you got there. I am anxious to try again with one of those little steel cones on a thicker piece of steel. I am looking at a piece of 3/4" (~19mm) steel plate right now which might just be the next victim. :D



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[*] posted on 8-1-2015 at 15:11
armor


Amateur human mind is difficult to understand how this is possible. A piece of soft copper pierces thick armor. Unbelievable. But it works ...:cool:...LL
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[*] posted on 8-1-2015 at 16:22


It is very amazing that it works, yes. Steel, and other materials also, behaves very differently when subjected to very high velocities and pressures.



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[*] posted on 8-1-2015 at 23:25


Quote: Originally posted by Hennig Brand  
I am anxious to try again with one of those little steel cones on a thicker piece of steel. I am looking at a piece of 3/4" (~19mm) steel plate right now which might just be the next victim. :D


These little buggers really leave a mark, don't they :D For 19mm steel plate I would suggest charge masses upwards of 5g (more likely 7-9g of nitroester/nitramine base for a clean penetration with mediocre confinement and presicion).
Really excellent work on the steel plate btw! Very clean uniform penetration, no deflection or divided jet patterns. Looking forward to the test results with 19mm plate :)




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[*] posted on 9-1-2015 at 09:26


A long time back, in high school, I combined some of my metal working shop and art class projects- I tried making my own Copper blanks and then enameling these, besides other metal jewelry work. Never considered back then, I could have added some of my organic chemistry extra curricular activities to those projects? Probably not with instructor approval though.

I always wanted some of the nicer specialty tools for small metal working jobs...

Like these precision punches



image.jpg - 53kB

Or this set which also makes concave/convex discs...

Even if the profile wasn't exactly correct, a little free hand work with a diamond home on a punch mounted in drill press chuck could be done to alter such punches.



image.jpg - 55kB

I am a tool slut.

[Edited on 9-1-2015 by Bert]




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[*] posted on 9-1-2015 at 11:59


Here's the results of a 7g phlegmatized (10% PIB+methyl riccinoleate) PETN charge on 15mm steel plate:

20140328_194223.jpg - 1.3MB 20140328_201517.jpg - 1.2MB

20140328_202227.jpg - 1.6MB 20140328_202338.jpg - 1.6MB 20140328_203353.jpg - 950kB 20140328_202815.jpg - 1.2MB

I managed to recover the carrot...what a blessed find....the bastard was stuck at the outer exiting verge of the crater :D
I guess just 100mg more energetic would have sufficed and it would have left the target to never be found again.


20140328_202631.jpg - 1.1MB

[Edited on 9-1-2015 by markx]




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[*] posted on 9-1-2015 at 12:06


Such a cute little hole punch.

It would be really nice to include a scale with such pictures, or use a piece of graph paper of a specified size for the background?




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[*] posted on 9-1-2015 at 12:37


Quote: Originally posted by Bert  
Such a cute little hole punch.

It would be really nice to include a scale with such pictures, or use a piece of graph paper of a specified size for the background?


I know, I know....I stand ashamed, facing multiple accusations of chronical incapabablity to include a proper scale reference in the graphical evidence of experimental results. But I was having just too much fun and the excitement of success can do weird things to ones' judgement for executing the correct scientifical method:D
In light of this the reported thickness of the plate can be viewed as anecdotal reference and I have no intention to file an appeal on the matter.
I promise to correct my wicked ways in future reports :D




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[*] posted on 9-1-2015 at 15:09


But it's hard, isn't it? Doing the experiment is fun, even measuring the result is fun. But to document things properly, that's actually hard work. At least it is for me, and I suspect I'm not the only one. I think we owe our self to push each other, not only to do good note-keeping but also to share our work with enough detail so that others can replicate it. That's what science is all about really.

Other than that little derailment, I just wanted to say: Keep up the good work! I love reading about them, all the cool experiments you do.

I'm seriously considering revisiting my experiments with drawing liners, especially now that I have my furnace working. Sadly I have so much on my plate I can barely focus on the things I <i>have</i> to do even though it's my own projects that keep me going. I don't have time to do a write-up, but if others are looking into this route I'm sure I could offer up some advice.

This of course requires access to a lathe and quite a bit of theory, I have a PDF of "Handbook of Die Design", second edition from McGraw-Hill that was quite useful there. Don't know where I got it from but I'm sure you will find it if you search.
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[*] posted on 9-1-2015 at 15:13


Nice work Markx. I like those cutters and dies Bert, but I think I am going to make one on the lathe to start. I think most of my problems have been because of asymmetrical liners, which may be what you were picking up on.

Yes Fulmen, the research, the experimentation and the documentation all take work. Most things done of any significance take work. People who do the work generally don't like to be belittled. We have been getting a look at LL's greatest hits, which is nice and I appreciate it, but there is maybe as much or even more to learn from some of the things others did (like myself) where things didn't go perfectly.


[Edited on 9-1-2015 by Hennig Brand]




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[*] posted on 9-1-2015 at 15:24


Access to a lathe greatly improves your chances. Accuracy, not only in the manufacture of the liner but equally in the assembly greatly affects performance. If you can, make tools for the assembly as well. As always, the more effort you put into something the more you can expect in return. I suspect EFPs are somewhat more forgiving in this aspect.
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[*] posted on 9-1-2015 at 19:45


I agree hennig, for all our successes how many failures have we had? I know I tested at least 10 charges before I got any significant penetration nd these failures are what presses us to try again. If we got it perfect first go then where is the incentive to keep researching? Keep it up guys this is a great thread and its great to see it revived. In the near future I plan to attempt some EFP devices for myself. Its been a while since my last SC test and have found some nice old AUS pennies to try. They are copper only and 1.8mm thick. getting other factors right they should work well. Also hennig did you aim the efp somehow? Like a laser dot from the center of the charge and a mark on the target to match, just to see how far off supposed center the projectile strikes? If it hits close to the prediction then increased standoff should not be a worry with missing the target. NP



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[*] posted on 10-1-2015 at 03:31


Glad to hear you are enjoying the thread. Regarding aiming an EFP, I was on rough ground, but the target and charge were both placed on a piece of plywood, which was relatively flat, which lined them up. A carpenters square can be used to make sure the charge is parallel to the wood rest and perpendicular to the target. The target and charge can be placed close together to ensure that they are lined up at the right height and then pulled apart to the desired standoff. Once at the right standoff I literally lied down on the ground behind the charge and sighted the EFP in by looking down the top of the charge casing. It is amazing how well the EFP can be aimed by sighting down the casing. A laser level would likely be a great way to line up an EFP with a target.



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[*] posted on 10-1-2015 at 15:29
smart container


Using polystyrene container is very easy. Production takes 20 minutes. The entire device buries itself in the sand. EFP warhead can be very precisely adjusted. At the right angle 90x90 deg. Easy, cheap, fast. Safe. For the brave hero (for video) Needless to bury...:cool:...LL

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[*] posted on 10-1-2015 at 21:42


You are using the plasticized perchlorate explosive described elsewhere as a an "active" backing plate/counter charge on the side of propelling charge opposite the EFP?

Thanks for the graph paper background! What size are the squares?


image.jpg - 61kB

[Edited on 11-1-2015 by Bert]




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[*] posted on 11-1-2015 at 02:50
steel 12


Yes, slow plastic explosive is described in the thread cheddite, pag. 7, title AP plastic. Squares on the paper are 5x5mm. The mass used around 4g. Slow AP plastic as an active supporting plate. The detonation propagates in two directions. Thus it is meant. Here are the results of this report. Unfortunately, the device was not accurate. I do not know where the error is. Everything was made very accurately. EFP-quality effect is difficult to create. Despite this, 12 mm steel shot through. Although little, but still...:cool:..LL

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[*] posted on 11-1-2015 at 05:36


Congratulations! Excellent results LL! Now this impact looks more like the projectile had time and space to form into a rather decent slug. It also looks like the projectile parted or perhaps it is the impact of the separation plate that you had between the main charge and the backcharge. I guess the root cause of the partitions lies in the overcomplicated design of the separated charges. The separation plate, the copper tube through it coupled with the initiator....all this creates quite a mess at the back end of the main "brizant" charge when fired and can possibly do more harm than good to the overall performance of the device (by disrupting the uniform propagation of detonation wave in the main charge)
If one could embed a centrally placed initator between the main and backing charge in direct contact with both of them and with no penetrating channels through the backing charge then I think this concept might work magnificent. Technically very demanding task though...




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