SC failure - reasons?

[xoo1246]

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<small>[ December 11, 2002, 12:59 PM: Message edited by: xoo1246 ]</small>

[kingspaz]

ok, rivers flow fast downstram than upstream because of the weight of all the water above flowing down. right? so if you had a less than 1mm thick cone then there wouldn't be much mass of copper behind the tip of the jet. E = 1/2MV^2 so if you have more mass theres more energy behind it. not sure what else could have gone wrong. you have any pictures that would describe the setup better?

<small>[ August 07, 2002, 08:00 AM: Message edited by: kingspaz ]</small>

[xoo1246]

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<small>[ December 11, 2002, 12:58 PM: Message edited by: xoo1246 ]</small>

[a_bab]

The lenght of the tube used to keep the charge at some distance from the target seems to be too big for me.

Also, the container: in order to preserve the jet forming for the very first moments, you need a stronger material. Using some metallic tube instead of plastic might improve your SC.

...But I think that the thickness of your copper sheet is too small, as Kingspaz said.

[kingspaz]

sorry xoo, didn't see the pics. i now see how it was setup. ever tried a lead cone? easier to shape and can easily be melted at the join to form a single solid cone.

[nbk2000]

Another thing is the hole looks awfully wet. Might water have seeped in between the cone and the target? Water would have absorbed the jet.

Also, was the cone attached firmly enough to the container to resist the explosion long enough to be collapsed? Or was it pushed out intact?

Shit, tornado sirens going. Gotta go.

[xoo1246]

The container was water proof, and no there was no water, only damp clay. No residue from a pushed out cone was found, the cone was attached with hot glue.
I thought the detonation wave was able to travel through the main charge before things(on the other side) started to move too much.

Or are you saying the detonation in one end of the charge applies a pressure on the not yet detonated material, thus pushing the cone out? What container could in that case withstand that (high)pressure.
It doesn't make sense to me.

It can have been the Plastic bonded HMTD having a longer d.t.d. time (it has, foolish to use it :mad: )thus generating a overpressure in the container pushing the cone out(?). If that is the case, my recent claymore could have had the same problems.

Also my first SC, a bad one, with a very imperfect cone contaning I can't remember how much ANNM(say 200-300 grams) with less % NM blew a large hole in fairly thick pipe. That liners was also glued in place, although the container was metalic and the standoff was closer. That HMTD was not bonded with a binder. This fellow didn't even scratch the target.
Maybe I should contruct a copy and try it with straight HMTD.

<small>[ August 07, 2002, 02:05 PM: Message edited by: xoo1246 ]</small>

[a_bab]

The idea is that the container should be more resistent than the liner. In your case it isn't. That's why you succedeed with your first SC: you used a metallic container.
Also the distance to the target which should be 1,5 times greater that the charge diam. if I remember correctly.

I know that using plastic is very tempting because of the ready available materials, but I would use metal pipe for casing.

[xoo1246]

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<small>[ December 11, 2002, 12:58 PM: Message edited by: xoo1246 ]</small>

[Yi]

With a fast enough VoD a metal casing should not be necessary. Even with AP/AN or HMDT/AN mixtures a small (1 ounce) shaped charge can be made that will happily punch through 3mm steel plate.

<a href="http://incoherent.topcities.com/Explosions/Pictures/an.htm" target="_blank">Look here</a>

I don't know why the charge did not work. The charge possibly worked just like a shaped charge with a cavity only. If the dent in the steel was smaller than the diameter of the charge then it shows that the cavity at least directed the blast towards the plate.

The mass of the liner should increase the effectiveness of the charge however I think that it is not as signifigant as the addition of the shockwaves.

[kingspaz]

xoo, i've just thought...you know when you look into the shaped charge from the open end where you load the explosive? was the explosive right in the gap between the cone and container? like in such a way that it covered the whole of the inside of the cone?
its really hard to explain what i mean. if it wasn't then the cone wouldn't have collapsed properly.

[nbk2000]

Plus DIRECT contact of the explosive to the liner (nothing, not even plastic sheeting between it and the explosive), a single integral piece of copper as a liner (not a cut sheet rolled into a cone), No air bubbles or voids, total saturation of the AN with NM, metal casing, liner solidly fixed in place, and other factors come to mind.

[Microtek]

I have tested quite a number of SCs in the past, though all of them were much smaller ( largest I ever did was 11 mm diameter ).
I can't see why it didn't work; it seems like it should to me except for one thing, which is that I have never tried ANNM and therefore don't know how suitable it is. I have read in Urbanski's books that AN in mixtures often detonate a short time after the explosive with which it is mixed. This may disrupt the funktioning of the SC ( but that's just to give some sort of constructive critique ).
Other than that I'd suggest you use smaller SCs and test them on wood. This way, you'll be able to see the channel left by the jet and you'll also be able to recover the jet material if you use a thick enough layer of wood. This could give you a better feel for what works in SC design and then you can try your best deigns on metal afterwards.
Finally, I think you should use a unitary explosive if possible ( RDX or picric acid ).

[xoo1246]

Thanks for all the critique. We'll see what can be done.

[FarbrorBosse]

I would recommend you to use another explosive.

If you cannot make RDX or PETN due to lack of chemicals I recommend you make some good o'l fashion AP and use that in your whole device.

When you make a SC it is very important you use an explosive with high detonation velocity to punch and accelerate the metal to create a jet.

It is however not needed to surround it by concrete/metal or other types of containers since you use a HE and HE detonates so you do not need to build up the same pressure around the device as you need with BP.

I made a SC by having an AL cone (0.1mm thick) on 4 7.5 cm legs, then I placed a plastic bag of PETN powder over it (~150g) and a detonator made of AP on the top. This thing blew a pretty hole in the target.

Making a SC with a low bristant explosive is as bright as making a black powder SC, it just won't work.
(you can create other types of SC with low bristant explosive having RDX in the front blasting a hole, then a slower shockwave with more gas from a slower explosive comes after the primary jet and fills the target with hot gas and high pressure.)

I think your cone is ok, your plastic container looks awfully good, and will be great if you replace your AN/NM mix.

With your current setup and about 200g better explosive (RDX, PETN, AP) you don't have to bother much if you have the cone 1 cone length or 3 to the target it will blast a decent hole in that target of yours.

I pierced 3 computers with one similar charge and could have pierced maybe a 4:th if the jet would not hit a HDD on its way through the 3:rd computer.

[edit]:
I think nbk2000, Microtek and Yi made some good points... just wanted to give my point of view.

<small>[ August 08, 2002, 05:26 PM: Message edited by: FarbrorBosse ]</small>

[Eliteforum]

FarbrorBosse - You are correct in saying that you need a explosive with a high VOD, but by saying using AP for the whole explosive would yeild that a void comment, as AP doesn't have a very high VOD, granted it's "ok", but in reality and proper testing a HE would be best.

[FarbrorBosse]

Eliteforum: ---"but by saying using AP for the whole explosive would yeild that a void comment"---

That sentence was a bit hard for me to understand, maybe cause I did not listen properly to the english lessons in school anyway..I guess you mean yield? and think I have no idea what I'm talking about when I mention AP together with PETN and RDX?

Please Eliteforum, I do my posts based on what I have learned and tests I have done, not words based on some internet.txt file.

I use PETN for most of my SC tests and RDX where there is less need of much explosive, but for most people who does not have access to a full lab environment it can be hard to make those explosives.

I know AP works quite well for a SC, not by reading book nr#1302 by some Dr.Richardin in germany who made research in 1895 and whatever he had to said about the compound.

AP will _not_ be as great as RDX but will do the job.
(200g will definitely do the job on that little box he had on the picture.)

I think xoo1246 not only wanted to know 1000 reasons why his device might not have worked properly, but also know a way to work around it, to be able to make that little hole so I should have mailed him instead in the first place, but decided to post since there seem to be a lot more people who might need to know to :)

So as I posted previously either he will use RDX or PETN or as a 2:nd alternative he could use AP, who is not much worse then TNT as a matter of fact...

[Eliteforum]

What I was basically saying is that, AP isn't the best choice of explosive.

[Anthony]

You'll get about 5000m/s max from AP, ANNM should give up to about 7000m/s. But if this thing about the components of ANNM detonating non-simultanously is true, then the higher VOD is no advantage.

[xoo1246]

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<small>[ December 11, 2002, 12:59 PM: Message edited by: xoo1246 ]</small>

[Chris Shiherlis]

Just a few remarks:
ANNM can be used for shaped charges.
The container for the explosive doesn't have to be strong, let alone metal (even paper will work).
A plastic sheet between the liner and the explosive is no problem.

So the SC should have worked. It is most probably the badly packed explosive on top of the liner (it seems immpossible to me to get the explosive neatly fitting around the liner when using a plastic bag) or the way of detonation (or maybe you just had a low order detonation). But a liner thinner than 1mm might also be a bit too thin. For LSC's (linear shaped charges) a thin liner is necessary because there's not much explosive on top of it. But with normal shaped charges you can use some thicker liners because they use more explosive (but I wouldn't use thicker than 2mm).

And Yi, I like the pictures you present but according to them the SC don't seem to work, I'm sorry to say. The plates seem just to be punctured by fragments and/or the Munroe effect and there are no signs of the cutting effect of a jet.
For pictures of a real cutting effect, download the the book "improvised shaped charges" on the site from Wantsomfet (by the way, are you still alive? And is there any progress with your sensitised ANNM topic :) ).

[RDX*]

During the last week I have carried out some SC tests. In previous experiments I have got the conclusion that the angel of the cone should be around 65 degrees so I used 65˚ for all of my experiments. I also used 250 g of KNO3 and 50 ml NM as a standard charge. I lit the explosive with a half film canister of AP. The cone thinness I used was between 0,2mm and 0,8 mm. I found out that the thickness played a big part in the result. I got best result when I used 0,8mm cone, It probably isn’t a bad idea to use &gt;0,8 mm for SC.
But I haven’t the material to try &gt;1mm cones. One thing that I discovered was that the best distance between the charge and the target is around 1cm. It probably has to doe with the explosive.

<a href="http://www.geocities.com/rdxgames/Target4.jpg" target="_blank">www.geocities.com/rdxgames/Target4.jpg</a>
(picture: the metal plate is 10mm thick and the hole measure 30*35 mm)

Ps. in the future will I do some experiment with thicker pates &gt;20mm and LSC.

For more info and pictures on the experiments download <a href="http://www.geocities.com/rdxgames/SC_tests.zip" target="_blank">http://www.geocities.com/rdxgames/SC_tests.zip</a>

<small>[ August 11, 2002, 03:02 PM: Message edited by: RDX* ]</small>

[ENGINEERKILLER]

I would suspect that you had a low order this is real common with ANNM that has sat for any amount of time. If it was a low order it would still invert the cone on impact with the target.

<small>[ August 12, 2002, 03:32 PM: Message edited by: ENGINEERKILLER ]</small>

[xoo1246]

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<small>[ December 11, 2002, 12:58 PM: Message edited by: xoo1246 ]</small>

[ENGINEERKILLER]

O.K I misunderstood the time frame you were working in my mistake .I've used ANNM that was that had sat for 24 hours and instead of a nice clean detonation with complete consumption of the plastic casing I returned to the shot and found bits and pieces of the casing.No AN residue like you would see with an explosive that had been scattered by a cap. The detonation also lacked the nice clean crack that you normaly hear instead it was just a big bang.

<small>[ August 12, 2002, 03:31 PM: Message edited by: ENGINEERKILLER ]</small>

[xoo1246]

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<small>[ December 11, 2002, 12:57 PM: Message edited by: xoo1246 ]</small>

[Chris Shiherlis]

I agree, a low order detonation is not very likely. It happens with some NM explosives and is caused by a detonator that's not strong enough. And there's only a small "range" at which this low order detonation occurs: just a bit stronger initiation leads to detonation at normal velocity and just a bit weaker initiation leads to no detonation at all. Sadly I don't have the papers at hand in which I read this. So there's is some truth in saying that Kine pack detonates at full speed or not at all.
But since ANNM is very sensitive, the 2 gram HTMD should have gotten the ANNM to detonate at full speed. But I was just looking for a reason why your SC didn't work.
And I understand it's also not caused by the plastic bag used to protect the copper liner from the AN. And it certainly isn't due to the ANNM explosive itself. I've seen a patent in which they use this explosive to destroy (nuclear) warheads with a shaped charge: a shaped charge filled with AN is "activated" at the appropiate moment by emptying the compartment with NM into the AN (I'm again sorry I don't have the patent number, but it shouldn't be to hard to find).

Anyway the question WHY your SC didn't work is still not answered and it get's more difficult.
Last possibility: the liner is not good. I experienced that it is hard to tell what liner you must use because with shaped charges, if you change one thing, the whole thing changes. All variables are influencing the performance of a shaped charge: sort of liner, thickness, angle, sort of explosive, amount of explosive, stand off distance, etc.
It might just be that your liner was just to thin. The small mark your SC produced on the steel plate might indicate a small jet was indeed produced instead of a lot of shrapnel from the liner (which would have punctured the steel plate along with the Munroe effect). So since there is no puncturing and no shrapnel nor a Munroe effect observed, I would say your SC produced a jet and you just need a thicker liner for a more powerfull jet. (but don't use a liner that's too thick, you will then observe puncturing by shrapnel/Munroe effect. 1mm should be a good thickness to start with).
But then again, I could be totally wrong and the failure was produced because you didn't pray enough to the God of explosives, you should always do a quick prayer before an attempted detonation :) .

<small>[ August 15, 2002, 11:49 AM: Message edited by: Chris Shiherlis ]</small>

[A-BOMB]

Well this topic has brought up an old idea I had to use a flashlight as a SC. So heres my idea, you find a old metal flashlight(like a C or D) and take out all the internals. First you would gather you explosive, detonator, a 9volt of a couple of AA's and a IC555 timer ciruit, you remove the glass lence and replace with a thin plastic or exclude the step altogether. Next take out the reflector and replace with your charge liner(or if the reflector is metal and conical you use the reflector as the liner) after that you solder wires to the terminats on the lightbulb and pull them up so when you pour in you explosive the wires are through it. Then put in your electric detonator, wire the detonater to the IC555 and to the flashlights switch, along with the lightbulb so when the switch is on for too many seconds the charge goes off. Now take you battery and wire it into the circuit now take a dead battery of the type used in the flashlight and cut off the bottom and epoxey into place, so when the battery cap is tooken off it looks like there is a battery in the flashlight. Then wrap some ducktape on the outside of the flashlight. Now is done your doorknob perciering SC in a flashlight, so when a pig looks at it and turns it on for a few seconds the bulb lights and takes off the battery cap it looks like a geniune flashlight, so when at the target you use the ducktape on the outside to attach the SC flashlight to the doorknob and you turn on the switch and wait till the timer finishes counting down and boom. This would probley be better explained with a drawing but I'm to lazy.

[Anthony]

It's fiendish... but rather extravagent for blowing someone's door knob off, y'know it'd piss them off and be rather inconvinient when they want to open the door, but what's the point? :)

I'd have a seperate, hidden switch somewhere to start the timer. If Mr cop decides to play with your flashlight for longer than you thought he would...

[Chris Shiherlis]

OK back to topic again. XOO I didn't see your pictures (I'm a kind of computer illiterate, so can't you make it easier so that I just have to click once too get to see them, just like that RDX-guy did :) ), so I didn't actually see how that plate looks like.
But I tried some LSC's with different liners and the effects differed dramatically. Some LSC's produced just shrapnel and no jet, and the metal was just punctured and bended. Other LSC's were very effective and really cut the metal with the jet: a very sharp and linear cut with smooth edges and the metal stretched at the exit side, and also it was coloured inside with the (atomized) liner metal.
Some other LSC's produced a jet (and thus no shrapnel) but didn't cut the metal and the only result would be a small line "carved" in the metal and to both sides of the line there was atomized metal liner visuable (just like a spraypaint).
So if your metal plate with the small mark looks like this (no punturing, no/little bending, a small dent/mark like it's hit by a nail, and some atomized liner around it), you just should use a thicker liner of the same material (and exactly the same configuration as your first SC).
And I think aluminium is better suited as a liner: less energy necessary to form a jet. A thickness of 1-2mm should work. Also the Stand Off distance I use is just a bit bigger than the height of the cone: about 1.5-1.75 times the height).
Hopefully this information is any helpfull.

Oh yeah, don't you forget to say a prayer :) .

<small>[ August 18, 2002, 07:54 AM: Message edited by: Chris Shiherlis ]</small>

[xoo1246]

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<small>[ December 11, 2002, 12:57 PM: Message edited by: xoo1246 ]</small>

[Einstein]

I was thinking that I should try SC myself. Here is a picture of Finnish Military SC #59:
<a href="http://koti.mbnet.fi/vaakkupr/panos.jpg" target="_blank">http://koti.mbnet.fi/vaakkupr/panos.jpg</a>
I don´t understand why the cone is flat at the smaller (inner) side? It would be VERY good to get that kind of thing at hands :D It has 600 grams of explosive and total weight is 1 kilo. Without stand-offs it makes about 20-25cm deep hole to asphalt.

+++++++++++++++++++++++++++++++++++++++++++++

Posting 115kb sized pictures is NOT appreciated. It takes forever for us poor DUN'ers to read a post while waiting for your huge ass picture to download.

If it's over 30kb, post a link instead.

NBK

-Edit-
Sorry NBK about that. I didn´t think that when I uploaded it, because I have a very speedy (512/128) cable modem :p I´m really sorry about what happened, but human learns from his mistakes. Now I have learned one new thing (thanks to you! :D ) I remeber this from now on.

<small>[ August 26, 2002, 01:36 AM: Message edited by: Einstein ]</small>

[Chris Shiherlis]

Yi, I'm terribly sorry. I overlooked the first plate. Seems that SC worked very well (no puncturing by fragments, little bending, small sharp hole, plate coloured by a copper layer). And the SC's look nice/professional anyway. Only with the second plate there's a lot puncturing by fragments, at first glance I would say that one didn't work. But maybe just a small part of the liner was transformed in a jet and cut the plate followed by the fragments which punctured it (but the effect of a SC is not supposed to look like that).
Anyway, my apology, especially because you put a lot of effort in it.

[Yi]

Thanks for the apology it has raised my opinion of you..The comment did piss me off a little...but I didn't comment as it was a while back (was on holiday for a while) and there were other posts there already.

On the second charge the liner was slightly too thick (the first too thin)...on a repeat of the experiment with an identical liner but APAN instead of HMTDAN did not breach the plate..only made a sharp dent in the plate (will take pictures sometime) and no copper colouring.

More experimentation will be done with faster explosives and liners, but for now i'm working on some detonator tests on lead plate.

[edit: Just me being retarted with techical info]

<small>[ August 31, 2002, 06:05 PM: Message edited by: Yi ]</small>

[Chris Shiherlis]

So I'm no longer an arrogant asshole, just an asshole right? :) .
But seriously, I'm a bit suprised that HMTDAN is capable of forming a jet out of a copper liner, even if it is just 0.25mm thick.
I always thought you needed a secondary high explosive with a VoD of at least 6000 m/s. Even with such explosives you can't use too thick liners and it's relatively difficult to get an effective jet produced. Many times you get the effect seen with your second plate: puncturing by fragments and the Monroe effect.
I use a NM explosive for my LSC's and a 1mm thick aluminium liner produces the best results but with a 2mm thick aluminium liner the penetration is already considerably less and 1mm brass is even worse.

So what I'm saying is that since you succeeded to construct a shaped charge with even a copper liner, the HMTDAN must have a considerable VoD. Or explosives with a low VoD (like HMTDAN???) might only be able to create a small jet out of only very thin liners and with a little penetration (but why then is APAN incapable of producing a jet?).
And explosives with a VoD exceeding 6000 m/s are able to produce bigger jets out of thicker liners and with greater speed and power and penetration.

So does anyone know the VoD of this new HTMDAN (and APAN) explosive? The effects of it compaired with some other explosives with known VoD like ANNM would give an indication (test it on a metal plate to get an indication of brisance and power).
Or maybe someone has a better explanation for all of this.

<small>[ September 01, 2002, 12:04 PM: Message edited by: Chris Shiherlis ]</small>

[kingspaz]

well what i'd guess is:
with HMTDAN, having a lower VoD (around 5000m/s?) less energy is in the jet which forms. the way i see it is nomatter what the VoD so long as the cone is collapsed in a reasonable uniform manner then the jet should form. the key difference being it flies along at a lower speed. with a higher VoD explosive such as RDX the jet flies at a higher speed.
E = 1/2mv^2
therefore the total energy is directly related to the velocity of the jet. higher velocity = greater penetration as the jet hits the target with more energy.

[simply RED]

The ultimate explosive for shaped charges for me was a mixture of silicone paste and PETN. The silicone paste is used for chips cooling in electronics. Sold in every electronic shop! 7-10% paste does wonders to the fine powdered PETN... The mixture looks like C-4, white and has a very good density.
The ideal mathereal for shaped charges cavity is copper, but the alloy that is used in the jar caps is laso very good...
Even for big shaped charges the thickness of the cavity sheet does not need to be more then 1 mm. The angle is 45 or 50 degrees. The standoff distance is 1,5 cone diameters, the lenght of the charge is 1,5 or 2 cone heights...

<small>[ September 03, 2002, 10:48 AM: Message edited by: simply RED ]</small>