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Author: Subject: Unconventional Shaped Charges
greenlight
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[*] posted on 22-8-2015 at 02:22


Nux is the charge weight the same as the last CSC?



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[*] posted on 22-8-2015 at 02:34


Quote: Originally posted by greenlight  
Nux is the charge weight the same as the last CSC?


5 grams same as the last one the angle former gave 6 mm extra hight.i am setting it up for a test right now.
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[*] posted on 22-8-2015 at 02:39


Nice, what was the total explosive height?
Post results when u can:)




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[*] posted on 22-8-2015 at 03:27


Results are in no penertration, got a nice looking straight hole over 2.5mmin dia can get a 1.6 mm rod to 29 mm deep in the hole, will have to do test again now :mad:

20150822_205253.jpg - 501kB20150822_211715.jpg - 905kB20150822_211705.jpg - 795kB
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[*] posted on 22-8-2015 at 03:37


Looks like a much cleaner hole this time though!
Hmmm, I think the variables affecting the penetration problem would have to be standoff or explosive weight/height. I will have further look through some papers.
Did the last CSC test you did make it 29mm through the plate as well?




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[*] posted on 22-8-2015 at 03:47


Cant tell on the first one cause the carrot is blocking the hole but the bulge on the back is the same.
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[*] posted on 22-8-2015 at 10:26


Make a cone out of thinner copper sheet. I think that will improve results if everything else is kept the same.
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[*] posted on 22-8-2015 at 15:53


I am not sure but if you would have smaller angle cone this will improve it.
Going from 60 degree to 45 or 30 degree cone angle would be better!

[Edited on 23-8-2015 by ecos]
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[*] posted on 22-8-2015 at 19:38


60 degrees is about the optimum angle for CSC's.
I have read on here somewhere:
When the cone angle is smaller, the velocity of the jet is higher but its mass becomes much smaller.
When the cone angle is larger, the jet velocity decreases, but slug/carrot velocity increases.




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[*] posted on 22-8-2015 at 19:56


I am making a new batch of etn plastic with higher sg hopfully that will make a difference nuxy
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[*] posted on 23-8-2015 at 02:18


What do you mean by the abbreviation sg?
Forgive me if its something obvious.




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[*] posted on 23-8-2015 at 02:22


i think he mean specific gravity but not sure , just guessing :)

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[*] posted on 23-8-2015 at 03:02


Yeah I was thinking that too, he must mean higher density plastic.



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[*] posted on 23-8-2015 at 03:09


Sorry I should have said grams per cc
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[*] posted on 23-8-2015 at 03:43


I went through the document optimized conical shaped charges and photographed a couple of tables that may have answers to some of the problems that have been arising with the CSC's. The document studys cone angle/diameter, standoff, explosive height/width, liner material/thickness, and explosive type and tamper.

The first table is different cone angle's and standoff's and their effects.
The second is jet penetration effects from varying explosive height.
The third is a diagram of the final results from all test's incorporated into making a perfect conical shaped charge.

[Edited on 23-8-2015 by greenlight]

20150823_192755.jpg - 7.4MB

[Edited on 23-8-2015 by greenlight]

20150823_192851.jpg - 8.8MB 20150823_192953.jpg - 6.7MB

It seems I was wrong and Ecos was right and the optimum cone angle is 45 degrees with 60 degrees still being effective but any more angle and the penetration starts to drop off.

So the optimum CSC configuration seems to be:

Cone apex angle 45 Degrees
Liner thickness 0.01 CD (1% cone diameter)
Explosive height 1.5 -2 CD
Explosive width 1-1.4 D
Optimum standoff 2-6 CD

[Edited on 23-8-2015 by greenlight]

[Edited on 23-8-2015 by greenlight]




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[*] posted on 23-8-2015 at 04:05


Thanks Greenlight for the great info, nuxy.
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[*] posted on 23-8-2015 at 05:22


Per my undersraning, if metal powder like fe2o3 is added. This would improve the propagation wave inside the EM. 1% would be enough.

According to parameters of greenlight we expect around 5 cm penetration. Good luck nex vomica
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[*] posted on 23-8-2015 at 05:34


I drew the improvements you posted greenlight into a new shaped charge design thoughts?



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[*] posted on 23-8-2015 at 05:43


You shouldnt insert the whole detonater inside the explosive. Just 1/3 detonator length should be in.
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[*] posted on 23-8-2015 at 06:10


Nux, that looks very good:D

Cone angle = 45 good
Liner thickness = 1%CD good
Explosive height = 2×CD good

The shape of the charge casing and the extra head height should nake for nice detonation wave formation.

[Edited on 23-8-2015 by greenlight]




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[*] posted on 23-8-2015 at 06:29


I don't think you have enough head height there but I hope I'm wrong. The smaller the angle the more force is needed to collapse the cone, so you're expending more energy into collapsing the cone by decreasing the angle and with such a small charge I'm afraid there won't be enough energy left for deep penetration. Again, I hope you'll prove me wrong.
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[*] posted on 23-8-2015 at 06:54


Hmmm, i will try and find some documents with head height tests in them and see.



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[*] posted on 23-8-2015 at 08:43


I can only find tests on explosive height not actual head height even though they are nearly the same (increase in explosive height=increase in head height) but after looking at a lot of shaped charge diagrams, a lot of them have about the same head height as Nux's, like the diagram I posted yesterday.
If I am correct, it is still going to be the about the same force, but the higher the head height, the flatter and more planar and well developed (to a certain point) the detonation wave gets before it interacts with the liner.
Optimizing shaped conical charges document says this:

"Using a liner apex angle of 45 degrees and a liner thickness of O.OlD, the explosive height (H) was varied between O.5D and 3D. The jet penetration increases as the explosive height increases, however, there is no significant increase in jet penetration for explosive heights greater than about 1.5D. Therefore, a value for H of 1.5D to 2D appears to be sufficient."

Your diagram is at 2xCD explosive height Nux and the document reported no improvement from there on, even testing up to 3xCD.
You could always make two identical CSC's, but vary the head/exploive height on them to see what works best for your size charge because the CSC's in those tests are 9.8cm in diameter compared to your 1.5.

[Edited on 23-8-2015 by greenlight]




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[*] posted on 23-8-2015 at 15:15


I need to find some 0.16 copper first but the caseing wont be a problem , I will try the drawing dimensions first time around, thanks Greenlight nuxy
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[*] posted on 26-8-2015 at 02:00


Hi All,

I think making concave metal hemisphere shaped charge is much easier than a cone. check figure below.

The cone should be symmetric , apex should be in the center, .....etc , this makes cone design a real challenge

Most of the videos I saw and papers I read prefer cone ! , What I know that a cone would have deeper penetration distance and the hemisphere would have wider hole in the target.

is there any other preferences for using cone rather than hemisphere ?

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