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Author: Subject: Unconventional Shaped Charges
gnitseretni
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[*] posted on 14-5-2010 at 11:46


NUKE, aren't you curious what material the target was made off? Maybe have someone else take a look at it, someone with a degree in metallurgy. Or maybe an experienced welder may know, surely there has to be a welder in your area, have him take a look at it. Or maybe the guys here can help you if you give a little more information?
I mean hell, you have to be a little curious, right??
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Plasmapyrobattics
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[*] posted on 14-5-2010 at 12:24


At ease. The esteemed cranially flatulent Sergeant may go play with his tank now... granny’s water tank in the back yard... quick!! ...before neurotic Sergeant Fart goes on another one of those tell-tale erratic, aggressive PTSD trips laced with foaming mouth tourettes ... And don’t go reading too many books on PMS now... Granny won’t approve... Oh and remember to take some Lithium...

:D

PS: Be openhearted. Try reading this post with a great sense of humor.

:P
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NUKE
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[*] posted on 14-5-2010 at 12:30


@gnitseretni

Yes I am curious about it! It's just the lathe guy hadn't come by to take a look at it. I'm pretty sure I would get my answer if he had seen it before... Real life inspection is better than the internet one isn't it?
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hinz
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[*] posted on 14-5-2010 at 13:47


Awesome work, Nuke!

The shrapnel damage of the trees is especially impressive, this is the reason why steel casings are usually avoided =).

The target rod looks also looks like cast iron or hardened to me, as it scatted upon impact and broke without bending.

To determine for sure whether it's cast iron or steel, the easiest method would probably be if you to take a small sample of your target, embed it in epoxy and polish it.

If no microscope is available, it would be also possible to determine the hardness of the target, as cast iron is usually softer than steel.

The micro structure of cast iron looks different (under an optical microscope) than the micro structure of normal steel, as cast iron with high carbon content forms graphite flakes:


In low-carbon steel, the grain boundaries are usually visible if polished, so if your sample looks like this under the microscope, its probably normal steel:



Also normal steel:


To see several examples of polished metal microsctructures, I found a nice page:
http://www.georgesbasement.com/Microstructures/Introduction....


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12AX7
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[*] posted on 14-5-2010 at 13:51


Spark test.



Seven Transistor Labs LLC http://seventransistorlabs.com/
Electronic Design, from Concept to Layout.
Need engineering assistance? Drop me a message!
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hissingnoise
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[*] posted on 14-5-2010 at 14:10


Tim, I think it's already been subjected to the 'Mother of All' spark tests. . .
The close scrutiny of such testing though, is a bit, er, problematic!

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[*] posted on 14-5-2010 at 15:12


Spark test for metals:

http://en.wikipedia.org/wiki/Spark_testing_metals

It must be either cast iron or mild steel. I can't imagine
anyone throwing out a piece like that of any good quality
alloy.
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[*] posted on 25-5-2010 at 11:42


Here is an unconventional shaped charge!

http://new.ba-bamail.co.il/View.aspx?emailid=1295&member...

Very nice design




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pjig
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wink.gif posted on 30-5-2010 at 08:18


NICE! Thats a lot of stand off for a charge, but its very effective looking.
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hissingnoise
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[*] posted on 30-5-2010 at 08:28


A smaller standoff would be more likely to penetrate doors than knock them in. . .

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[*] posted on 3-6-2010 at 13:02


Hi,

i've got one question about these improvised SCs based on cones like Whinebottle bottoms or martini glasses:

Does the glass act as a liner? Or does it just hold the explosive in the right position, giving it the right shape?
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franklyn
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[*] posted on 3-6-2010 at 18:08


Glass is a very effective liner having reasonable density,
but inferior to metals which are denser.

.
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Justin
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[*] posted on 4-6-2010 at 02:46


However as Axt stated, a good glass cone will be much better than a crappy copper one, and its almost impossible to get/make a good metal cone unless you get one from a dummy military shaped charge, I'll stick with glass as its much cheaper and much much easier to come by than a metal one
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Microtek
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[*] posted on 4-6-2010 at 11:02


Density is not the only factor that determines the effectiveness of a given liner material. In fact, bulk modulus or Young modulus may be a better indicator of suitability.

Quoting myself from the "Martini glass SC" thread:


Quote:

In "Liners for Shaped Charges", Held uses a ranking of liner materials based on maximum jet speed times the square root of the liner density. He further states that, as a rough approximation, max jet speed can be estimated as 2.34 times "bulk sound velocity" of the liner material.
Now, I'm not entirely certain of what he means by bulk sound velocity, but from the numbers in the table (table 1) it seems to be the speed of longitudinal waves.

The speed of longitudinal waves can be calculated if shear and bulk moduli or Young modulus and Poisson ratio are known, but the interesting point is that the formula features the square root of the density in the denominator.
In the ranking formula, this cancels out with the square root (density) factor.

This means that as a means of ranking liner materials, you can simply use the square root of (K+ 4G/3), where K is the bulk modulus and G is the shear modulus. Or you could look up longitudinal sound velocity and multiply that with the square root of the density.

As an even simpler (and less accurate) method you could just use the square root of Youngs modulus.

There are probably many aberrations that would deviate from this ranking system (for instance, it rates steel higher than copper), but it accurately predicts several well known phenomena such as the fact that lead is very poor, that aluminum is decent and so is glass.



Glass and many other ceramics are quite stiff, giving them high bulk sound velocity which is probably what makes them good candidates for SCs.
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mabuse_
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[*] posted on 5-6-2010 at 12:09


Thanks.
I think I'll try winebottle, since i found no other common household object.

Another question:

My ANNMAL is working fine.
Is it worth the effort to try something else?

And if you say yes, than what is the best kind of energetic material to use, considering the fact that i don't have access to nitric acid better than 65% and i've got no distillation equipment.
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Microtek
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[*] posted on 5-6-2010 at 12:43


Well, if you can get sulfuric acid you could make any of the nitric esters (without distillation). So if you can get pentaerythritol, erythritol, mannitol and so on, you are ready to go. Also, Your ANNMAl would probably be more effective if you got rid of the Al.
Personally I think that the amount of explosive required for a wine bottle SC (bearing in mind that nitric esters are relatively sensitive) is a bit much, so I would suggest looking for a smaller cone (a glass funnel maybe if you want to use glass).
The smallest succesful SC I have tested was based on a brass cone 5 mm OD at the base, 0.3 mm wall thickness, 60 degree angle and less than 0.2 g PETN. It penetrated between 6 and 7 mm steel even though the cone was slightly misaligned. So you see, it is quite possible to experiment with SCs at a much smaller and therefore safer scale.
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[*] posted on 6-6-2010 at 03:34


im going to be testing out a candle lightbulb shaped charge soon (30mm tulip shaped glass cone), i will use 30g etn as the filler. the main problem now is finding 2 inches of steel to test it on. the only thick enough steel i can find is the side of an old large hammer, but then the problem of aiming the charge correctly arises.

About nukes target material, im suprised no one picked up on this. he measured the rod as: 0.422m with 0.06 radius.

39
-------------------------- = 8200(ish) kgm^-3 =about the density of a mainly ferrous material.
Pi x 0.06^2 x 0.422

as many people have stated, the density of the material is the main factor that affects penetration depth, not hardness. i would be curious to see this tested, but i currently do not have enough time or resources to produce enough identical charges for an accurate test.
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[*] posted on 6-6-2010 at 09:57


I have shot charges a-while back that consisted of ANNM blended with a binder of DBSP ,and Aluminium (@2% or so, to sensitize the mix). This made a mold-able simi-plastic, It seemed to have a great power output compared to most AN mix's, and work for SC's. It fails terribly in comparison to nitric esters as a SC filler( for power), but will suffice.

My question Is how much is lost "VOD" when using this small amount of Aluminium?V.S.What is gained in cap sensitivity for the mix? Is it worth the Aluminium in the mix, or just remove it all together and initiate it with a hotter charge..?
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mabuse_
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[*] posted on 6-6-2010 at 12:03


Hi,


Quote:

a glass funnel maybe if you want to use glass

yeah, i've allready serched for glass funnels, but they are quite expensive...

Quote:

Personally I think that the amount of explosive required for a wine bottle SC (bearing in mind that nitric esters are relatively sensitive) is a bit much

Well, It doesn't gets much louder ;) And ANNM ist not that expensive, about 150 or 200g should do...

I'd like to try smaller ones, but as i haven't found proper cones yet...


Quote:

Your ANNMAl would probably be more effective if you got rid of the Al.

I've read that before somewhere...


Quote:

My question Is how much is lost "VOD" when using this small amount of Aluminium?V.S.What is gained in cap sensitivity for the mix? Is it worth the Aluminium in the mix, or just remove it all together and initiate it with a hotter charge..?

my solution whould be to use aluminium only close-by to the detonator. This way both advantages should be combined or what do you think?
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[*] posted on 7-6-2010 at 04:36


Quote: Originally posted by Microtek  
Density is not the only factor that determines the effectiveness of a given liner material.
In fact, bulk modulus or Young modulus may be a better indicator of suitability.


In short , what works is known after exhaustively trying everything
that can be made into a liner. Now it remains to make sense of it in
some formula. There are as already noted many candidates , just as
there are candidate formulas for predicting performance of explosives.

Speed of sound of some substances is seen in the attached tables.
In the lower one , a selection from the CRC handbook ,
Longitudinal ( sound ) speeds are given in the left column marked V1

Substance densities are given in the CRC handbook from 4-39 onward

PS
Beryllium has the distinction of propagating sound at ~ 13 Km/sec
far beyond the detonation velocity of any known explosive. This
makes it incapable of spalling as other metals will do if the applied
detonation wave exceeds it's speed of sound. One reason why it is
used as tamp as well as neutron reflector in implosion atomic bombs.

.

SC Penetration.gif - 4kB Speeds of sound in materials .gif - 14kB Speeds of Sound CRC.gif - 29kB
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Microtek
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[*] posted on 8-6-2010 at 13:33


@Franklyn:
As you say, many thing have been tested and there is no question that the best compromise between cost and effectiveness is copper, while the highest performance is achieved with things like tungsten or molybdenum.

However, sometimes it is useful for the amateur to have a predictive tool to give some indication of the usefulness of the materials he has at his disposal. For instance, copper is not so easily machined with cutting tools while brass is (and additionally, where I am at least, copper rod is not easy to find in shops), so it is very useful to be able to look at easily found numbers to determine whether it is likely to be a good liner material.
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The WiZard is In
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[*] posted on 8-6-2010 at 16:18
Jetcord


My ca. 1973 Jetcord® catalogue (the triangular shaped charge
used for controlled demolitions &c.) notes that they make
it using either - Lead, aluminium, copper or silver.
There is no price listing for silver. The 4 000 gr/ft
RDX, copper was $100 a foot for 50-99 feet and
$29 ft for 1000 feet.

Jetcord is a product of Explosive Technologies, Fairfield
California.

They were developing 7 000 gr/ft Jetcord (over a pound of
explosive per foot.)

The 4 000 had a minimum penetration of 1.3" and a minimum severance of 2+ inches. (Rolled steel.)
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[*] posted on 9-6-2010 at 18:05


Theres alot to be relearned from the first 10pgs or therabouts of the beginning of the OP.AN/NM/SA makes a first rate simple shaped charge explosive.
Good detail on linear charges even comparisons of how much further a csc will penetrate mild steel as compared armored steel thanks to military charts unlike claims by others who said I was the one unfamamiliar with the charcteristics of metal as relates to SCs.I would think an effort would be made to not squander the info thats proven itself and instead apply yourselves to improving on whats gone before.Instead Reinventing the wheel over and over and not doing a good job at that.

By the way an earlier comment regarding the size of the test plate we so recently debated got me thinking.At the advertised dimensions and my limited math skills the wieght of the target "steel" is something like 240Lbs!? How is it Nuke you managed to wrestle that through what appears an overgrown dense forest or does the name really fit?.Being something Im familiar with 12 in of steel rail wieghs 80lbs how is it the entire target wieghs approx 40kilos?And has the shape(irregular form) and color of a white softwood tree branch.Very similar cracks
with same white softwood interior.Are we in fact looking at a northeastern softwood my gullible friends insist is a metal or is the accent not as put on as it sounds and its a eurasians species.
Also as no one has the time to view the previous genuine amazing SC results made of a sadly done piece of fiberglass no one seems to dare view.This is now a good haven for members from totse etc. as compared to the first pages of a decent Original posts stickie by very professwional folks now gone bad.To call anything but the premade cone a well made fabrication is an insult to reality.
Carefully done epoxy securing the CSC? nicely banded standoff leggs LOL. Ther isnt enough standoff in the steel tubing to accomodate the charge and standoff? Piss poor planning is no substitute for careful assembly.Looks like shit frankly and I suspect the performance matched otherwise we would see a carefully laid out sequence of the events and a schematic of construction as are in the beginning of this at one time excellent resource.:(
Finally for the moment Wizard take a look @ AXT's home improvised linear charges and the commercial ones your touting are far from impressive.And yes I am out to insult most
of you who have posted recently, what little verifiable work thats being done is less than substandard compared to just a few yrs previously.I dont see anyone trying to turn thir own CSC's,Fabricate single efps let alone multiple efps.Proundly dissapointing for the experts you all are!:mad:
[Edited on 10-6-2010 by grndpndr]

[Edited on 10-6-2010 by grndpndr]

[Edited on 10-6-2010 by grndpndr]

[Edited on 10-6-2010 by grndpndr]
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nitro-genes
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[*] posted on 13-6-2010 at 05:11


Interesting post Franklyn!

Surprised to see such a high speed of sound for tungsten carbide, at 6655 m/s! It is incredibly dense and abbrassion resistant as well. I wonder if anyone has been crazy enough to produce a liner out of this material, hehe...
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[*] posted on 14-6-2010 at 12:29


Liner from that thing would probably barely deform! :D

Anyone tried an Osmium liner!?
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