Sciencemadness Discussion Board

Unconventional Shaped Charges

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Axt - 24-6-2004 at 19:49

<center><b><font size="4">Cylindrical Lined Charges</b></font></center>

I'd like a topic on unconventional shaped charges, obviously a practical use but it has a lot of science behind it, so <i>hopefully</i> it isnt locked.

Starting off, I found a reference to cylindrical lined charges in fundamentals of shaped charges (walters, Zukas) only a single sentence in 400 pages is devoted to this, and states:

<center><i>"Cylindrical liners are capable of generating high velocity (and low mass) jets."</i></center>

I decided to try this, as according to the Birkhoff theory, theoretically cylindrical liners will produce a jet 2x the VOD of the explosive! of course this wont happen in an improvised device but thats the highest theoretical velocity possible. Close to zero standoff should provide the best performance since the jet should be fully formed within the cavity.

The design of the charges was incredibly simple, two liners were chosen, both being 1mm thick aluminium but varying in diametre, 20mm and 16mm, both were 65mm in length, tape was used over the hole to keep explosive out of the cavity. The charge casing was light DWV PVC, 50mm wide, 110mm high. Charge was ANNMSA 140:100:70. Initiation was a commercial #8 detonator. Target was 1 inch thick steel plate. Below shows the finished liners, casing and charge performance.

<center><img src="http://www.sciencemadness.org/scipics/axt/cyliners.jpg">
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On detonation the charges performed exceptionally, both completely penetrated the 1" target. Its also testament to the effectiveness of the ANNMSA composition, note the large dent in the steel where the charges were placed. The penetration dimensions are shown below.

16mm liner: Entry = 14mm, Exit = 14mm
20mm liner: Entry = 23mm, Exit = 11mm

Therefore the 20mm liner started off wider but taped back to less then the 16mm liner, while the 16mm provided a constant diametre hole. This suggests that the small diametre liner would provide a deeper penetration if used on a thicker target. Spalling was present on the exit and might suggest that plugging also contributed in producing the large holes. Though no "plugs" were found.<br><br>

[Edited on 7-6-2005 by chemoleo]

The_Davster - 24-6-2004 at 21:35

Wow, thats pretty impressive. How much ANNMSA was used in the charges? What does the SA stand for, Silver Azide or Silver Acetylide?

[Edited on 25-6-2004 by rogue chemist]

Axt - 24-6-2004 at 21:48

SA = Sulphuric acid

The ratio given was the charge weight in grams, 140g AN, 100g NM and 70g SA. So 310g all up.

I'll rephrase to make sense of the spalling (the large exit wound), it was mostly created by the zero standoff and power of the impact on the surface of the metal, but the 20mm in particular had a rough exit which may have been blown out in a plug rather then by plastic displacement. The 50:16 charge diametre to liner diametre wins.

[Edited on 25-6-2004 by Axt]

Axt - 25-6-2004 at 01:05

Great references Myuo!

ANNMSA takes the form of large wet crystals, which may seem strange considering the amount of liquid in the mix. However after the AN is dissolved into the H2SO4 and the NM is added it crystalises out of the acid trapping all the liquid in its structure. I wont test with another explosive, due to the amount of effort it takes to make it. ANNMSA is easy and <i>is</i> a high VOD explosive. The only comparisons I can provide is the the commercial emulsion in the MEKP comparisons <a href="http://www.geocities.com/roguemovies5/">movie</a> against the ANNMSA movie on the same page, as they are the same volume against the same target, there is no comparison!

I wont scan FOSC, as its being re-printed in a softcover version. Not that I care about lining the authors pockets but I think if people are genuinely interested they will just buy the book. Unavailable texts are something different and I fully appreciate some of the rare scans people provide. FOSC is still available through isee.org and a few other places. Definately one for the bookshelf if you are interested in this. Though it tends to go straight from the basics to the advanced leaving out the middle ground, for example there hardly a mention of LSC's.

My interest primary lies in things I can test for myself, theres enough of those that I'll be occupied for a looooong time :D

chemoleo - 25-6-2004 at 07:01

Yes, Myuo deleted his post again. I remember him doing this in several other threads too - I wonder why?
It's very strange. And annoying if he provides several useful references :(


Axt, do you have references on ANNMSA?
I don't quite understand the principle of this explosive, particualry the presence of sulphuric acid?!? It is basically a mixture of ammonium sulphate, nitromethane and conc. HNO3?

PS Vulture, are you saying the average thread is crap? Or that the average forbidden practical discussion is crap? :o:o
Aren't we nice and positive :P;)

[Edited on 25-6-2004 by chemoleo]

Axt - 25-6-2004 at 17:28

No references, just something I made up with to increase the sensitivity of O balanced ANNM.

NM/HNO3 Is a very brisant explosive in its own right, and the intimate contact between these liquids is better then NM/AN for example. Ammonium sulphate will happily explode as well, and acts to hold it into a solid structure.

Though im not sure about the safety of this mix, pure NM mixed with pure HNO3 is very sensitive. Theres many dilutants in this mix however NH4NO3/NH4HSO4/H2SO4/HNO3/NH4CH2NO2 probably more... I'll try shooting it to get some measure of its safety.

A better visual on the holes:

<center><img src="http://www.sciencemadness.org/scipics/axt/cylinderholes.jpg"></center>

Im more impressed by the spalling from the shock transmission through the steel. Never seen it first hand before.


[Edited on 7-6-2005 by chemoleo]

Tomlinson - 26-6-2004 at 13:34

Combined spall wave and shaped charge warhead. ;)

It would be very interesting to see how deep your charges could cut as according to theory your shaped charge should form incoherent jets as I understand it. It would also be interesting to see the penetration effect of long cavity charges of this type as they could be made very long with little effort and limited amounts of explosives.

Axt - 27-6-2004 at 03:10

I can see where your incoherent jet theory is arising from, but most theorys seem to go to shit once you get the the extremes such as a cylinder, I wont speculate as to whats happening. Myuo posted some nice references regarding acceleration of jets through a cylinder, seemingly the effective VOD can be increased by using a hollow cylindrical cavity in its length since the accelerated jet initiates the explosive as it passes through it.

I will probably try greater standoff to define the jet effect. For all I know it may well be accelerated shock waves acting as a hole punch!, which should diminish quickly as standoff is increased.


[Edited on 28-6-2004 by Axt]

Axt - 28-6-2004 at 00:15

<center><b><font size="4">Tulip Lined Charges</b></font></center>

Literature refers to this shape as the "tulip" which is in fact an ogive, for which I have posted on before where bullet jackets were used as the liner material. I havnt seen this shape used in anything but experimental designs so its unlikely to do anything that cant be done better by the conical, hemispherical or trumpet shapes. The picture below shows the jet shape from tulip liner, note the large head of the jet followed by the thin tail.

<center><img src="http://www.sciencemadness.org/scipics/axt/tulipjet.jpg"></center>

In addition to the bullet jackets I've attempted to use a chrome plated steel motorcycle part as a liner, as can be seen below it was a complete failure, I'll blame the liner material. Around 600g of ANNMSA was used with 2LD standoff. It simply splattered the liner over a 3" circle into the steel with the fragments penetrating at most 3/4".

<center><img src="http://www.sciencemadness.org/scipics/axt/tulipmon.jpg">
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A better and easier source for tulip shaped liners would be aluminium nose cones for model aeroplanes, most will have a hole on the apex for attaching it to the plane but the liners should still work. The Japanese used a hole through the apex of their liners during WWII.

80g of the ANNMSA composition was shot today with a .25-06, no detonation occured, which is good.

NOTE - There may be a temporary geocities preoblem with the movie ..

[Edited on 7-6-2005 by chemoleo]

Maniak - 28-6-2004 at 13:15

I´ve never tried any tulip lined charges. I have only some experiences with hemispherical liners. I´ve made liners from Cu plate (0,55mm thickness) and they can penetrate steel about 1,5 LD.
For example 20g of RDX plastick with Cu liner (15mm in diameter) completely pierced 2cm of steel and resulting hole is close to be constant in diameter (8-9mm).

Now I´m also interested in your cylindrical liners (thanx for this idea), because I´ve some Al and Cu pipes so I want to use them with my plastick:)

Axt - 1-7-2004 at 01:22

<center><b><font size="4">Linear Shaped Charges with Standoff</b></font></center>

<center><table cellspacing="30"><tr><td><img src="http://www.sciencemadness.org/scipics/axt/lineardia.jpg"></td><td><table cellpadding="3" border="1"><tr><td><b>Explosive</b></td><td>NM/70%HNO3 70:30</td></tr><tr><td><b>Charge weight</b></td><td>285g/m</td></tr><tr><td><b>Liner</b></td><td>20 x 1.4mm Al</td></tr><tr><td><b>Liner angle</b></td><td>90°</td></tr><tr><td><b>Standoff</b></td><td>10mm</td></ tr><tr><td><b>Target</b></td><td>6mm steel</td></tr></table></td></tr></table></center>

I wasn't going to post this as its not exactly "unconventional" but it does provide an easy way of intigrating the correct standoff into the charge with common materials. The linear shaped charge (LSC) is made by simply hot gluing a section of 25mm aluminium angle into a length of 20x20mm channel. By using these materials you have a LSC that with a capacity of 235ml per metre. The liner is 20mm wide with a standoff of 10mm, which is about right considering it is an improvised device therefore a slightly lower standoff is likely to provide the best performance.

A liquid explosive is the most practical for a long linear charge, therefore a charge of 70ml nitromethane and 30ml 70% nitric acid was used in the 420mm length of LSC. Initiation was a commercial #8 detonator.On detonation the charge cut the steel very cleanly, no other marks were on the plate, but it was bent back as expected. The picture below shows the detonation and the cleanliness of the cut over the full length of the LSC.

<center><img src="http://www.sciencemadness.org/scipics/axt/linearmon.jpg"><br><br>

[Edited on 7-6-2005 by chemoleo]

Axt - 23-7-2004 at 18:26

Same setup as above, but fired into a 1" steel plate to see the depth achieved. Managed 8mm deep cut though it skewed a bit as it was glued together.

<center><img src="http://www.sciencemadness.org/scipics/axt/lsccut.jpg">
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[Edited on 7-6-2005 by chemoleo]

Axt - 15-2-2005 at 05:59

<center><b><font size="4">Glass Lined Charges</b></font></center>
<center><table cellspacing="50"><tr><td><img src="http://www.sciencemadness.org/scipics/axt/glasslineddia.jpg"></td><td><table border="1"><tr><td><b>Liner</b></td><td>1mm Glass</td><tr><td><b>Shape</b></td><td>60° Conical</td></tr><tr><td><b>Diametre</b></td><td>50mm</td></tr><tr><td><b&g t;Confinement</b></td><td>2.5mm PVC</td></tr><tr><td><b>Charge</b></td><td>200g NM/70% HNO<sub>3</sub> 70:30</td></tr><tr><td><b>Head height</b></td><td>68mm</td></tr><tr><td><b>Initiator</b></td><td>0.5g PETN</td></tr><tr><td><b>Standoff</b></td><td>70mm</td></tr><tr><td><b>P enetration</b></td><td>>50mm steel</td></tr></table></td></tr></table></center>

Glass liners have been the topic of some debate, so I ran a test using a 50mm (2";) glass funnel, the spout was broken off and sealed by gluing on a piece of Al foil. The casing was made with 50mm DWV PVC fittings, with a 50mm slab adaptor used to hold the liner in position and provide the standoff.

NOTE: I used an extra fitting to provide greater head height (height of explosive between apex of cone & detonator) as it was too small once I glued it together. For best performance the head height, especially in an improvised charge should be at least 1.5X the liner diametre. This extra fitting isn't in the pictures, though can be seen in the movie.

<center><img src="http://www.sciencemadness.org/scipics/axt/glasschargeframes.jpg">
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The charge was fired into the same 2" slab of steel in the tulip charge above, but this time with better results. The jet
completely penetrated the steel with a clean even hole, opening at 23mm, exiting with 12mm.

<center><img src="http://www.sciencemadness.org/scipics/axt/funnelcharge.jpg"></center>

I found a comparison table for different demolition charges, which compare one glass to two steel lined charges. The glass compares favourably with the larger diametre steel lined charge which gives half the penetration of the glass. Check the attachment for the specifics of each charge which vary in charge weight, confinement etc. It seems glass will function equally well, or greater then steel. While copper is still better, a good glass cone will be far better then a shoddy copper one, and cheaper. The glass funnel used above was only $1.50.

[Edited on 16-2-2005 by Axt]

[Edited on 7-6-2005 by chemoleo]

steel-glass-charges.jpg - 42kB

chemoleo - 15-2-2005 at 19:33

Very impressive. 5 cm - that is VERY thick. It must have been a pain carrying this plate onto that hill of yours :P.

I wondered - are there computer simulations/programs that simulate/calculate the optimal standoff to achieve maximum penetration? Surely this can be calculated, a bit of fluid/gas (?) dynamics here should help?
I mean, a given liner shape (i.e. V/parabolic- shaped) with a given standoff should produce a calculable VoD of the gas jet at the point where it hits the target plate (providing the VoD of the explosive itself is known). I imagine the theory is similar to water sprays (i.e. in the case of a parabolic liner) all centering on one spot, where they repel each other and are sped up in due course (or in the case of gasses, compressed to enormous densities which are many hundreds/thousands of K hot) - which then hits the target plate. Hmm. Guess I have to look up the theory.

Anyway, rather than zooming in onto the optimal standoff by experimentation, couldn't a bit of theory/calculation be used?

[Edited on 16-2-2005 by chemoleo]

Axt - 16-2-2005 at 00:28

Actually the "precision" of the charge has more to do with the optimum standoff then anything else, especially when improvised which are far from perfect. An "ideal" charge with a cohearent jet will function well at very long standoff distances as, when compared to parting steel, air resistance is minimal. Though the less "ideal" or "precise" the charge the breakup of the jet governs the optimum standoff, for which the calculations are incredibly complex, the book reference in first post has some of the mathematical theory on jet breakup. While its likely possible to come up with a formula to get standoff from liner material, cone angle etc. it would have to be taken from experimental results. And I have no idea how "cohearent" a glass liner would be, high pressures do funny things!

Myrol - 17-2-2005 at 11:04

To Axt: Excellent work Master! Wow, the Explosion are quite impressive;) Especially the Nitromethane-Nitric Acid mix look's very cool!

I hope that I have time to test it at the weekend. These Cylindrical shaped charges are extremely easy IMO. Why not trying a Blast with Peroxide Watergel?

I didn't need very long and my Distillation setup is ready to produce LITERS of pure 60-85% H2O2. I think that H2O2 Explosives are stronger than ordinary mixes....back on topic:

Do you think that copper is again the best liner material for cylindrical shaped charges? I mean...even glass tubes wouldn't be that hard to get....:)

Quince - 17-2-2005 at 12:01

Axt, so when comparing cylinder to cone liners, for the same mass of charge, which one would you expect to achieve higher penetration? Also, it's not clear to me how the best cylinder height and diameter is determined given the mass of charge to be used.

[Edited on 17-2-2005 by Quince]

Atom - 17-2-2005 at 12:07

Maybe someone can now test DPPP's cutting power? I can't at the moment 'cause I haven't got the chemicals where I am now.

Quince - 17-2-2005 at 14:43

I thought the DPPP thread concluded that the proposed synthesis did not actually produce anything but some form of AP.

Also, my previous question in this thread still stands :)

[Edited on 17-2-2005 by Quince]

Axt - 17-2-2005 at 14:51

Quote:

Why not trying a Blast with Peroxide Watergel?


I don't think it would work well at all. Not only if it very hard to pack with consistancy, as it tends to hold large air voids that are really hard to get out if packed into a casing. It's VOD is also likely quite low. Keep it for general blasting where energy rather then VOD is needed.

Quote:
Do you think that copper is again the best liner material for cylindrical shaped charges?


Copper is undoubtedly one of the best, that why its used commercially/militarily. But that factors in cost and workability, actually platinum should make for a considerably better liner for those that dont mind spending thousands of dollars per charge :o

Quote:
Axt, so when comparing cylinder to cone liners, for the same mass of charge, which one would you expect to achieve higher penetration?


Conical. I dont know by which method the cylindrical liners are working, the 14mm ID of the liner creating a 14mm hole makes it seem like its acting like a hole punch, in which case it will either punch right through or not far at all. Using a bit of standoff would help show if it's the effect of a metal jet or the blast itself.

Quote:
Also, it's not clear to me how the best cylinder height and diameter is determined given the mass of charge to be used.


I dont know, I had a guess. Though it should scale well, so take the 16mm liner as the example and scale off it.

[Edited on 17-2-2005 by Axt]

Quince - 17-2-2005 at 14:59

Would blasting gelatin work well for a shaped charge? It's the easiest for me to make with my current resources.

Regarding liner materials, I'm curious as to what properties of the material determine its effectiveness. Why is copper better than many of the other materials?

searat - 23-2-2005 at 23:05

"Why is copper better than many of the other materials?" i think current is produced through the copper make a magntic field protecting the copper from the plasma, just a guess. MHD theory.

[Edited on 24-2-2005 by searat]

Quince - 24-2-2005 at 01:20

I think that would only work if the copper was a coil, as in a well known e-bomb design.

Axt - 24-2-2005 at 02:11

Plasma? .. theres no plasma.

Anyway, I wasn't replying to this as I really don't know the full answer. The "desirable" properties are stated in a number of references but there are always contradictions. For example why is lead so much worse then glass, even though lead is more dense and ductile? Where one would think glass will be low density and non-cohesive. Though lead will vaporise if too thin.

Anyway, heres the favourable characteristics of shaped charge jet materials, (extract from Walters, Zukas):

- High melting temperature (rules out lead, but why liquid jets are worse, I dont know).
- High density (enhance penetration)
- High bulk speed of sound (effects cohesiveness of jet, tip velocity).
- Grain texture/orientation (for good elongation of jet).
- High dynamic strength (when under severe pressure/strain, not necessarily high static strength).

The reference that will be of most interest is :

S. Buc. "Shaped Charge Liner Materials: Resources, Processes, Properties, Costs and Applications", SPC 91, pp. 282-2, (1993). <i>(anyone know what "SPC" refers to?</i>

And a table from:

Doig, A. "Some Metallurgical Aspects of Shaped Charge Liners". Journal Of Battlefield Technology, vol 1, No. 1. March 1998.

<center><img src="http://www.sciencemadness.org/scipics/axt/liner-materials.jpg"></center>


[Edited on 24-2-2005 by Axt]

[Edited on 7-6-2005 by chemoleo]

Quince - 24-2-2005 at 18:58

Thanks for the table. I've been thinking of trying this, but the only copper I have is about 2 mm thick, which is too much and can't be worked into a cone.

I'm curious as to how proper thickness is estimated.

searat - 25-2-2005 at 05:25

try a trangle, on sky with that deM program they used detcord copper trangle no stand off(small amount per area) and they cased it in rubber(which i think was used to bounce a shockwave back into the explosive to aid in ignition,and force the copper/plasma to get diercted.)

"Plasma? .. theres no plasma. " are you drunk when a explosive goes off it turns into plasma.
I know you don't think what i said was right but try this.

Timeline
1sec)the explosive is set off.
2sec)the temp rasies to 10,000C,and electrons spreed(like how a ark is greated,just before that)
2.5)electrons engise conductive metals,produceing a magntic feild.
2.6)most of the explosive has decomposed, the copper starts to turn to plasma,losing its field turning into a jet, with the shockwave and replie it speeds up to high speeds.
2.8)A plasma mass is made, due to the desnity of the metal more plasma per inch. copper is more conductive it easyly excepts electrons, breaking down quicker

I think heat conductive has some thing to do with it,add to last statment please!


[Edited on 25-2-2005 by searat]

[Edited on 25-2-2005 by searat]

Bert - 25-2-2005 at 08:18

Quote:
Originally posted by searat

"Plasma? .. theres no plasma. " are you drunk when a explosive goes off it turns into plasma.


Axt knows what he's talking about. You don't. Do some more research.:P Also learn to spellcheck-

The_Duke - 25-2-2005 at 08:28

Quote:
Originally posted by searat
Timeline
1sec)the explosive is set off.
2sec)the temp rasies to 10,000C,and electrons spreed(like how a ark is greated,just before that)
2.5)electrons engise conductive metals,produceing a magntic feild.
2.6)most of the explosive has decomposed, the copper starts to turn to plasma,losing its field turning into a jet, with the shockwave and replie it speeds up to high speeds.
2.8)A plasma mass is made, due to the desnity of the metal more plasma per inch. copper is more conductive it easyly excepts electrons, breaking down quicker


So all this happens in 2.8seconds huh? Well I guess you sure learned us then:P

WaveFront - 25-2-2005 at 10:23

I allways believed that in any conventional flame there was plasma. At least some amount of electrons and positive ions reacting and producing characteristical spectrum lines. The detector of Gas Chromatograps (TCD or FID) also presume the existence of ions in a flame isn´it?. Well, I humbly don´t understand how the plasma works in a shaped charge, but there must be plasma.

Axt - 25-2-2005 at 14:43

I apologise in assuming that you were talking about a jet of plasma doing the work, or are you? "the copper starts to turn to plasma, losing its field turning into a jet"? I can't tell what your talking about, it seems youve made a wrong assumption that you think is common knowledge.

It's a common misconception that plasma is responsible for the cutting effect of shaped charges, when its little more then a solid extrusion of the liner. Ionised gas is present, yes, in the explosion, not the jet.

searat - 25-2-2005 at 17:44

"the copper starts to turn to plasma, losing its field turning into a jet"? Metals close to a explosive can vaporise(plasma),while the copper is solid it can produce a magtnic field, when it vaporises it loses its field.

"a solid extrusion of the liner. " does that mean it fires a solid object.

I'am guessing your right about it not being a jet of plamsa, but just think what it would be like if it did,as a plasma cutter can slice through AL 120mm like butter

"So all this happens in 2.8seconds huh? "
i don't know the timeline, but it would be in milseconds, and as it wasn't bast on fact(that i know of), just my thoery, i could have used mintes.

[Edited on 26-2-2005 by searat]

[Edited on 26-2-2005 by searat]

chemoleo - 25-2-2005 at 17:48

Am I missing something completely?

What's a magnetic field got to do with a liner, and a shaped charge? Should we be using ferromagnetic compounds or what? What are you on about?

Further, your spelling... where shall I start? Anyone can do a spellcheck and so can YOU!

searat - 25-2-2005 at 17:54

"What's a magnetic field got to do with a liner, and a shaped charge? Should we be using ferromagnetic compounds or what? What are you on about? "

if you say a shape charge push the copper through the target, then using ferromagnetic compounds would greatly incease its effectiveness as it would offer some protection from the plasma.

"liner" does this meaning a shokwave warhead?

chemoleo - 25-2-2005 at 18:00

Oh dear.... I smell a troll...

searat - 25-2-2005 at 18:07

Whats a troll?.

I'am not going to change my mind, shape chage uses plasma to cut.

"The shape charge is an explosive warhead with its forward face hollowed out into a cone, which is then lined with a thin metal liner. If the charge is now detonated from its rear end, away from the liner, the effect of the detonation wave passing through the explosive is to deform the liner, subject it to immense pressure and heat, and turn it into a jet of molten metal and explosive gas moving at speeds in the region of 7-8,000 meters per second. When this jet strikes armour plate it simply forces a hole in the armour due to its combination of heat,mass and high velocity.

Quince - 25-2-2005 at 19:45

That quote doesn't mention plasma. The salient feature of plasma is near complete or complete ionisation. You've failed to argue that the jet is ionized to any significant extent (not to mention that your own quote says it's not all gas -- "molten metal" rather than "vaporized metal"!). Moreover, ionization of the fluid has nothing to do with cutting ability; the things that make a difference are listed by your quote, such as velocity.

You don't know what a troll is? I guess you are an Internet newbie too, not just a chemistry one. Check Wikipedia. Oh, wait, you probably don't know what that is either. http://en.wikipedia.org/wiki/Internet_troll

_____
Why, yes, I did get up on the wrong side of the bed this morning.

[Edited on 26-2-2005 by Quince]

Axt - 25-2-2005 at 21:33

Heh, I checked the wikipedia entry for "shaped charge", it's been corrected as it used to mention plasma as well.

Anyway enough of this discussion on plasma jets, its simply false. Even your own quote searat contradicts your argument. Its alright to come up with theories, but you have to base them on facts.

The following info is originally from:

von Holle, W. G, and Trimble, J. J. (1976), "Temperature Measurement of Shocked Copper plates and Shaped Charge Jets by Two-Color IR Radiometry," J. Appl. Phys. 47(6):2391-2394.

von Holle, W. G, and Trimble, J. J. (1977), "Temperature Measurement of Copper and Eutectic Metal Shaped Charge Jets," Ballistic Research Laboratory Report.

Quote:
The temperature of a jet from a 81.3mm diametre, 42° apex angle conical copper liner was measured. The explosive fill was comp B and a four-shot average of the jet temperature was 432°C with a standard deviation of 76°C.

Also measured the jet temperature of a 60° apex angle, 81.3mm diametre, tin/lead eutectic liner. The liner wall thickness was 2.54mm and the explosive fill was Comp B. The conical apex was slightly rounded to a 1mm radius. A four shot average revealed a jet temperature of 569°C with a standard deviation of 34°C. The tin-lead liner had a tip velocity of 6.3 km/s compared to the copper liner jet velocity of nearly 8 km/s (presumably liners of same dimensions).

It was concluded that the copper jet was solid and the lead-tin jet was liquid in spite of any scatter in the data.


[Edited on 26-2-2005 by Axt]

searat - 8-3-2005 at 21:18

Damn i hate to be wrong, but thanks for the info. If a shape charge uses the liner as a projectile, how would you incease its depth without useing more powerfull explosive?

" turn it into a jet of molten metal and ""explosive gas"" moving at speeds in the region of 7-8,000 meters"

That quote doesn't mention plasma?


[Edited on 9-3-2005 by searat]

Quince - 9-3-2005 at 23:46

Quote:
Damn i hate to be wrong

That's not good, because it can affect your judgement of whether you are wrong (and when to consider it). And that equates to stubborness.

searat - 12-3-2005 at 19:36

"whether you are wrong (and when to consider it). "
Yes people can be blind can't they, even internet infomation can be right at times.

Stop blowing the mods/boss's .

GIVE ME THE FACTS WHY I'AM WRONG NOT JUST SOME fm THAT HAS A NICE TITLE.

[Edited on 13-3-2005 by searat]

unconventional shaped charge

pramodattingal - 16-3-2005 at 08:45

hi friends
i have been doing experiments with shaped charge (lead liner ,90 degree cone dia,RDX ,BASED FLSC)for cutting 100 mm diameter steel tube by keeping FLSC INSIDE.BUT THE RESULT WAS POOR.is the 60 dergee cone angle better.what is the solution for the solving jet divergence during bending.
i had serch various book like fundamental of shaped charge but nothing is said about above things.in some report in net i found out 60 degree is better.i want to conferm and know the reson also.
please

Edit by chemoleo: Don't double post, and DO search before you post in the first place. This is the thread where you want to post it.


[Edited on 16-3-2005 by chemoleo]

Axt - 16-3-2005 at 09:13

Two cones joined at the apex, filled with explosive, initiated from the centre. Patent searches would be the best place to look, as this is common practice in the oil industry.

<center><img src="http://www.sciencemadness.org/scipics/axt/pipecutter.jpg"></center>

[Edited on 7-6-2005 by chemoleo]

Quince - 16-3-2005 at 12:47

Is this better than the configuration where the explosive is outside the pipe, with the two (wraparound) triangles meeting at the cutting line? By better, I mean using less total amount of explosive needed to succeed cutting a given pipe.

[Edited on 16-3-2005 by Quince]

searat - 17-3-2005 at 00:39

pic

1.jpg - 630kB

searat - 17-3-2005 at 00:49

pic

2.bmp - 186kB

unconventional shaped charge

pramodattingal - 17-3-2005 at 07:48

does the two cone answer was for me.
how can be it assembled inside the pipe
can u make me clear
my question related to 60 and 90 degree is unanswered

[Edited on 17-3-2005 by pramodattingal]

BASF - 17-3-2005 at 09:00

@Axt:
Excuse the simplicity of the question ;).....Some very impressive pictures taken....how did you protect yourself from shrapnel?

[Edited on 17-3-2005 by BASF]

Axt - 17-3-2005 at 09:20

Quote:
Originally posted by Quince
Is this better than the configuration where the explosive is outside the pipe, with the two (wraparound) triangles meeting at the cutting line?


I would expect the one above would be more efficient, especially for thicker pipe. Though I expect if given the choice most would attack it from the outside for simple convenience.

pramodattingal, your lack of fluency in the english language is no excuse for a lack of common sense, obviously its assembled before being slid down the pipe. 60° will likely be better in a well made charge. In your case I think the angle irrelevant as the precision of the charge is whats going to determine if it works or not, not the cone angle.

Quote:
how did you protect yourself from shrapnel


I'm not holding the camera. I never watch explosions without something between it and I. I'm about 100m away on the other side of that stump/rock in the pictures.

Chris The Great - 17-3-2005 at 11:55

You can see him duck down in the distance in the video of the second test. So there is a ditch, large rock and some distance between him and it.

easy coppercones?

nitro-genes - 5-4-2005 at 04:17

Although copper is one of the best liner materials, making a perfectly symmetrical liner out of coppersheet is very hard.
I tried so several times to make one out of multiple layers of 0.15mm sheet always resulting in a jet consisting out of 2 or more "fingers"
I never have this problem with 35 mm steel hemispheres made from.... coffeespoons! :D Always making a clean hole through 5 cm of mildsteel! for this I use 2 times diameter standoff with a NM based plastique...

Hopefully not pushing the discusion too much to the practical side, but could it be possible to make a good coppercone by winding and glueing 0.75mm-1mm copperwire over a 60 degree papercone?

Studies revealed that the liner collaps and penetration occur by hydrodynamic flow. So in my theory upon detonation the pieces of wire will collaps the normal way, plastisize together and form a normal coninuous jet.
Any thoughts?

[Edited on 5-4-2005 by nitro-genes]

[Edited on 5-4-2005 by nitro-genes]

[Edited on 5-4-2005 by nitro-genes]

[Edited on 5-4-2005 by nitro-genes]

copperwire liner

nitro-genes - 5-4-2005 at 11:24

Thanks for the references!

Especially the last one was pretty conclusive. I was amazed to see that wire having a circular cross-section has such a good (presumably) penetration ability, as it is stated in the same reference that the performance of a shaped charge liner is directly related to the maintaining of close dimensional tolerences on the liner. In particular the wall thickness!

Unfortunately there is nothing stated about the actual performance and jet formation of such liners in both patents. (You wouldn't expect so of course) Also in literature I could not find anything about this...

I fear that this theory needs some experimentational evidence to be conclusive ;) Also do I really like the fact that a liner made in this way would be a hell of a lot cheaper, as coppersheet costs me a fortune. As a student this is always an important factor! :D

Axt - 7-4-2005 at 05:15

Quote:
Originally posted by poiu
Speaking of references, the Walter & Zukas book looks rather interesting, expensive and out of print(?) (consider that a hint, generosity will be met with the same).


Is it out of print? I know it was recently listed at <a href="http://161.58.144.10/shopsite_sc/store/html/product100.html">isee.org</a> as being out of print, but that has now been removed.

I just dont have the capability of scanning a book at my house.

fatkangaroo - 29-4-2005 at 17:30

I was wondering if anyone has any more information on how to do the ANNMSA mix? I just tried it twice and ended up with a solid rock not wet crystals. I am not sure exactly how this is supposed to go.
I put 70grams of black 1835g/L sulfuric acid in a jar then slowly add the oven dried 140 g AN to the SA, it went yellow the jar warmed up and started giving off vapors, so I put the lid on and swirled untill it all dissolved. When I added the NM everything seemed to be going fine, added it all swirled it all up and let it sit. with in a minute a had a solid crust on the bottom and a fluid level on top. The cake is solid as a rock. Then I thought what the hell I will do it again and see what happens. Did it the same except let the vapours from adding AN to the SA blow away and ended up in the same end product. This cake is so hard I dont know how I will get it out of the jar.

Axt - 29-4-2005 at 22:04

I can only assume the problem is you trying to <i>swirl</i> a mobile, light liquid into a heavy viscous one. Pour the NM in and give it a <i>stir!</i>. Result is near immediate precipitation with no free pourable liquid. I just did it again to make sure of the quantities since the others were "field weighed". This is what it should look like.

<center><img src="http://www.sciencemadness.org/scipics/axt/annmsa-crystals-sm.jpg"></center>

I havn't played with the ratios to see if there is a better one, less H2SO4 may or may not be advantageous. The 140:100:70 ratio is balanced to CO2/H2O/N2/SO2 which seemed like a good place to start considering the following;

"Ammonium Nitrate 60% Ammonium Sulphate 40% Vod 2430 M/S @ .90g/cm3." Arthur Marshall Explosives.
(This is very close to H2O/N2/SO2 balanced as well)

BTW, whats with these dickheads (dickhead) that comes in, making good posts into this thread, ask me to scan a book, then delete their posts when I decline. Very odd.

[Edited on 30-4-2005 by Axt]

[Edited on 7-6-2005 by chemoleo]

fatkangaroo - 30-4-2005 at 12:05

Just tried again, this time vigorous stirring was used the second the NM went in. I stirred for around a minute and watched as the precipitate formed on the bottom and worked its way up untill everything was a solid mass of wet crystals;). Mine are so wet and thick I can hold the jar upside down and the mix does not move. I find it interesting that that doing the exact same thing but with swirling produces a different end product. I ended up adding more and more AN to the hard stuff in a attempt to soak up the excess fluid. I still have a fluid level even after adding a extra 60g AN. Its turned into a heavy block of whatever. . I am going to blow this big heavy bloody rock I have from the swirled mix as theres a good 140ml of NM in there, no point wasting it.
Cheers Axt for the point in the right direction.

nitro-genes - 6-7-2005 at 07:07

The making of the copper cones from wire was a complete failure. It is nearly impossible to get a perfectly symmetrical cone from wire alone... :(

I did stumble across an old artice on Wiley interscience:

The Behavior of Shaped Charges with open-poled hemispherical liners

Richard L. Summers 1, William P. Walters 1, Richard D. Dick 2

Is there anyone who can access this article or knows more about this principle?

and to Axt:

You seem to have purchased this book of Walter and Zukas. Does it contain al lot of experimental data like penetration depths with different explosive compositions, liner materials, shapes, standoff etc? Or is it more theoretical orientated?

[Edited on 6-7-2005 by nitro-genes]

Axt - 6-7-2005 at 12:14

Quote:
Originally posted by nitro-genes
Does it contain al lot of experimental data like penetration depths with different explosive compositions, liner materials, shapes, standoff etc? Or is it more theoretical orientated?


More theoretically orientated.

Contents:

1 Introduction to shaped charge concept
1.1 the shaped charge concept
1.2 Introduction to shaped charges
1.3 the nomenclature

2. history of shaped charges
2.1 the early history
2.2 the munroe effect
2.3 early shaped charge developement
2.4 the WWII era
2.5 the post WWII era

3.1 militatry applications
3.2 specialised applications
3.3 current applications

4. the gurney velocity approximation
4.1 the gurney expressions
4.2 extensions of the gurney method
4.3 the taylor angle approximation
4.4 application of the taylor and gurney methods

5. shaped charge jet formation
5.1 the birkhoff et. al. theory
5.2 comments on the birkhoff et al. solution
5.3 the PER theory
5.4 generalisation of shaped charge jet formation model
5.5 a sample calculation

6. the visco-plasti jet formation theory
6.1 the visco-plastic concept
6.2 the visco-plastic model
6.3 the equations for the visco-plastic jet formation model
6.4 jet coherency

7. comments on explosive welding, bonding and forming
7.1 explosive forming
7.2 explosive welding and bonding

8. the breakup of shaped charge jets
8.1 hydrocode simulation
8.2 analytical jet breakup models
8.3 semi-empirical formulas
8.4 the chou-carleone model
8.5 maximum jet velocity

9 shaped charge jet penetration
9.1 introduction
9.2 shaped charge jet penetration
9.3 variable velocity jets
9.4 particulated jets
9.5 compressible models
9.6 the virtual origin concept
9.7 rod penetration models

10. other aspects of shaped charges
10.1 fabrication of shaped charge liners
10.2 shaped charge precision assembly
10.3 scaling of shaped charges
10.4 shaped charge jet temperature studies

11. computational aspects of explosive - metal interactions
11.1 the governing equations
11.2 spatial discretization
11.3 mesh description
11.4 numerical integration
11.5 artificial viscosity
11.6 material models
11.7 material failure

12. wave propagation codes for shaped charge studies
12.1 summary of wave propagation code characteristics
12.2 code selection criteria
12.3 applications

13. shaped charge generalities
13.1 shaped charge variables
13.2 the explosive fill and initiation mode
13.3 jet characteristics

14. example applications
14.1 conical shaped charge liners
14.2 shaped charge liner collapse and jet formation
14.3 shaped charges with hemispherical liners
14.4 explosively formed penetrators
14.5 blasting and shaped charges
14.6 special applications and effects
14.7 shaped charge jet collisions

Chris The Great - 29-7-2005 at 13:54

I was just flipping through some of my info when I stumbled across this completely by accident. It is from The Chemistry and Technology of Explosives, Vol III, page 462

Quote:
An unconfirmed hypothesis was also formulated that ammonium nitrate in the presence of sulfuric acid undergoes dehydration to the formation of nitramine (Vol. III) which is a strong and unstable explosive compound.
A double salt of ammonium nitrate and sulphate, defined by the formula 2NH4NO3-(NH4)2SO4, is capable of detonating with a rate of 1000-1400 m/sec provided an exceptionally strong initiator and completely hermetic confinement are used. However, the detonation train of this double salt has a tendency to break up after travelling a short distance.

Going to the Nitramine entry (page 15) we see some more interesting stuff:

Quote:
Nitramine is believed to occur in an ammonium nitrate solution in an excess of concentrated sulfuric acid as a result of dehydration of this salt:
NH4NO3 --> NH2NO2 + H2O
Davis and Adams [8] report the following experimental observations in support of this supposition. On heating a solution of ammonium nitrate in sulfuric acid to 150*C, nitric acid cannot be distilled, but nitrous oxide is evolved, probably from the decomposition of nitramine. If, however, the solution is kept for a long time between 90 and 120*C, nitric acid can be obtained by distillion. The authors' conjecture is that the addition of water to the nitramine takes place according to reaction (16):
NH2NO2 + H2O --> NH3 + HNO3

Could be some nitramine that is helping this mixture be as powerful as it is. Perhaps some could be mixed up and allowed to stand for a couple weeks, and see if any gas is evolved (N2O) from nitramine decompostion. Nothing else in there should break down reapidly at room temperature.

I recently read a journal article (Diagnostic of Superfast Jets with 25 km/s Tip Velocities, Manfred Held, Propellants, Explosives, Pyrotechnics 23, pg 229-236, 1998) about a similar cylinderical shaped charge. In this case however the explosive did not surround the cyclinder, it sat on top of a metal slab 28mm thick, with a 20mm tall cylinder on the opposite side, 20mm diameter.
Using 3.9 kg of TNT/HMX 15/85, the jets travelled (through a vacuum) at nearly 25 km/s (the very tip looked like it was going roughly 24 km/s to me, but it faded into a point around there so it is difficult to see exactly how fast it is going using the pictures).
However, the jet looked to be very stable and straight, so I think that Axt is right when he said that the theory probably breaks down when applied to this type of shaped charge. When the charge was not centered, the jets went off to the side but they where still fairly straight, so I think that they are quite stable.

I plan to do some experimenting with these types of shaped charges, and attempt to measure the jet tip velocity as well as the explosive velocity, and see what kind of jet velocity you will get depending on the VoD of the explosive in question.

Axt - 30-7-2005 at 02:24

Thats some interesting stuff Chris, gives some possible reasoning to the AN/AS detonations not being as kaput as they look like they should be.

Quote:
and attempt to measure the jet tip velocity as well as the explosive velocity


Your going to clock a ~25km/s jet :o .. good luck :P

Anyhow, this threads been starved of pics for too long, melted lead from bullet jackets of .357 mag & .45 colt, charged with PETN/NG mixed to plastic consistancy. The hemispherical liners should be a lot more resistant to irregularities then the "spitzer" shapes as I posted before. Both penetrated the 5/8" steel, the .357 literally created a pin hole (can only fit one pin in the hole!) and the slug (carrot) was jammed in the entry.

<center><img src="http://www.sciencemadness.org/scipics/axt/bjsc-pics.jpg">

Yeh.. theres a <a href="http://ww1.webtop100.net/~62552/xmovies.webtop100.net/banners/xmovies.html">movie</a>.</center>

Chris The Great - 26-8-2005 at 23:31

Well I'm going to 'try'. I found a program to time microsecond events so I think it's getting feasible... We'll see.

Anyway, a though popped into my head about the ANNMSA mixtures. AN mixtures are generally very low density. However, in this case we add a very dense acid, and the whole mixture also recrystalizes, probably at a higher density than the original AN. I suspect that the end product is much more dense than a simple ANNM mixture.

Since increasing the density will cause a very large increase in explosive power, this might be the reason for the large performance increase more than anything else.

Just some thoughts...

Axt - 27-8-2005 at 09:13

Note that originally SA was used to increase the <i>sensitivity</i>, The increase in actual true "power" over straight ANNM is likely marginal or even worse, but your right, if ANNM is too saturated or pressed to too higher density it fails with 8 strength detonators. I too think its a combination of increased density (allowed due to an increased sensitivity) combined with a more intimate mix of fuel (NM) & oxidiser (HNO3).

But the sulphate ion doesnt add to explosive power, it should detract from it, thus the extra density it holds adds nothing to the explosive performance. The density increase is due to intimate mix of NM/HNO3 which is sensitive to detonation at its max density where ANNM or other AN fuel mixtures arn't.

Chris The Great - 27-8-2005 at 22:08

OPPS! I must have been tired when I posted that, I meant "detonation velocity and detonation pressure" and not power, but for some reason I put power while thinking of something completely different!

A small increase in density will have a very large increase in VoD and P, which is what I was trying to say. Hence the much greater brisance and apparent power of the ANNMSA mixture, even though the total energy release is less than ANNM on a weight basis.

Anyway, you're right about the better mixing as well. I think there are quite a few things which make this a much better explosive than straight ANNM.

Kinepak - 28-8-2005 at 03:48

Ive to say a few things: First: Do you think, that there is no reaction betwenn the NM and the "nitrating mixture" (AN, H2SO4)? I sound a bit strange to me. But i dont know. Then: Axt, i watched your movie from the tests (ANNM vs ANNMSA) several times and you definately can see, that the plain ANNM detonation is NOT complete! There is flying undetonated ANNM away. Thus the detonation was not that strong. But your tests are really great! Big compliment! Im very impressed from all your experiments and the sucsess! The ANNMSA could also be so strong, because of a reaction. Evt. Dinitromethane? I really dont know :D. But a little recommendation: Use UNNM :cool: ! Urea nitrate and NM.... thats the hell! I tested only 28g of it and it was horrible :o.

Axt - 28-8-2005 at 05:32

Im not sure what the acids effect on NM, I dont think its going to be totally inert but if it does for example form an equilibrium with another product its not likely to influence the actual performance. Some nitrations are done in NM solvent so there should be literature somewhere that gives a more definate answer.

Just to set the context regarding the ANNMSA movie your refering to, I posted this into E&W quite a while back but was deleted after I was banned. It shows its not a test of power rather sensitivity, and was in reply to someone using 40% NM.

Quote:

OK fella's I have to correct some things here, once you go too high in nitromethane concentration sensitivity diminishes not increases, most sensitive is actually around 15%, I have no dought that you get a powerful explosion from ANNM 60:40 but its not a "cap sensitive" mix and if left to sit for 2 minutes you end up with the AN sinking under liquid NM. Even 30:70 isnt reliable when initiated by a #8.

Nuclearattack: Where did you get the kinepak ratio of 60:40, Coming from the man himself, neither the solid is straight AN nor the liquid straight NM. The best information I have is that its a mix of NM/xylene, and i'll guess AN is mixed with a anti-caking agent, microballoon or other inert filler.

But but but ..... There IS a way of using a higher nitromethane percentage and make it even more sensitive, this is done by adding a portion of concentrated sulphuric acid, which ups the content of HNO3 sensitiser and thickens the mix up into a paste. Dont worry about any sulphate as that will happily go up with the rest, and the mix is compatible with most plastics and aluminium (at least in the short term).

((picture/movie))

The ratio Ive used is AN/NM/H2SO4 40:40:20, I fired two charges this morning to prove the point. The target and charge volume is the same as used on the MEKP tests to allow comparisons. I compared this mix to the ANNM 60:40 using #8 dets to show the poor detonation of the 60:40 with a commercial det. The difference is obvious with the ANNMSA creating a huge hole, the ANNM did actually manage a crack in the plate even though the detonation looks very weak. You could of course waste concentrated HNO3 instead of H2SO4. Try direct sensitising of NM with H2SO4 (without AN)!


BTW: This is a SC thread!

Kinepak - 29-8-2005 at 03:29

Ah I see.... Ive a question to Axt: You did a test with a Polyamide Resin HE made from PETN, PIB and Polyamide Resin right? Could you please tell me, what you used exactly and how the procedure was? This mixtures should also be a good choice for LSC. What does the Polyamide Resin affect in that mixture? And finally: What was your impression? I would be nice if you answer these questions!

Axt - 29-8-2005 at 22:17

Polyamide resin is one part of some epoxy glues, forget what solvent I used. You may be able to find references to its use as a plasticiser (It gets a mention here http://www.rsc.org/pdf/books/pb2500sc.pdf combined with RDX).

Its convenient, but going with blu-tac or bubblegum gives a better non sticky, elacticy consistancy. PIB is likely in blu-tac and PIB/styrene-butadiene in bubblegum. Both are main components in C4 & semtex respectively, so take your pick. Both extractable with xylene. You'll have to add a bit of oil to the bubblegum binder to keep it soft.

[Edited on 30-8-2005 by Axt]

Kinepak - 30-8-2005 at 03:06

Yea thanks! Ive already tried it. Ive a big solid block of PIB here :D. But thats not the problem. If I mix the PIB with the PETN and let the naphta (i used with gas, called naphta, to let the PIB swelling in) vaporize, i get a plastik thing. But the problem: Its not sticky enough! Its only elastic....! And so I thought, that you used the polyamide resin to improve that. You say that oil would work? What about vaseline? Hmm....Ill give it a go with vaseline. But all advices are welcome!

Axt - 30-8-2005 at 03:45

The point was to make it non-sticky, but yeh you can make it sticky with the addition of polyamide resin.

This is a shaped charge thread, thus I see no reason to have it sticky.


[Edited on 30-8-2005 by Axt]

Chris The Great - 31-8-2005 at 22:59

Bombs from bubblegum eh? Looks like I've got to visit the candy store....

Thanks for clearing up the ANNMSA issue for me. I did not realize that the test you did was to show the much greater detonability of the mixture compared to ANNM, I thought the video was to show how much more powerful it was!
This caused some condusion on my part as I thought that it also exebited much greater performance as well as the fact it was much easier to detonate! Now I understand!

An interesting thing I noticed about the cylinderical charges is the large diameter penetration. Looking at all of your other shaped charge tests, none show such a large diameter penetration. I found this very surprising when I stopped and thought about it.
Is there any reason why this might happen? The very close proximity to the explosive, so the metal was driven through from the explosion, even though it wasn't part of the jet?

Axt - 1-9-2005 at 06:42

I think its more likely a hole-punch effect, I dont think it a coincidence that the 16mm liner just happened to create an even 14mm hole (the inside diametre of the liner). I think the result would be a lot different if it were provided with a bit of standoff.

I taped and uploaded a movie from a documentary on the discovery channel named "What a blast" showing a shaped charge penetrating 1.5" steel.

Some issues with it, the explosive they use, PE-4, isn't the same as C4 as is stated. Rather it contains a few percent more plasticiser for a softer consistancy. They again state that the copper jet is molten, when its well documentated that its not, and the animation is horrendous. Its ~5MB, 2.5min, .wmv format.

<center><img src="http://ww1.webtop100.net/~62552/xmovies.webtop100.net/banners/discovery-channel-shaped-charge.jpg">
<a href="http://ww1.webtop100.net/~62552/xmovies.webtop100.net/banners/xmovies.html">movie</a></center>

Fulmen - 27-9-2005 at 02:52

Greetings everybody.

First off, I really can't understand the reason for using a nasty chemical as sulphuric acid as a sensitizer when a

simple activation processs (patent no. 4,093,478) does the trick. I've used it with good success by wetting

fertilizer grade AN with 1% water, drying it (80°C for 1 hour) and finally reducing it to a powder in a coffee mill.

Mixed with 15% NM and 3% Xylene it is initiated by a No.6 cap, although I usually use a bit of det-cord as a

booster.

Axt, I'm truly impressed by your work. I have done a few experiments with liners, nice to see I'm not the only one.

A jacket from a cal.30 FMJ placed in a 30-06 case with Comp C (appr. 3.5g) easily penetrated 12mm of mild steel

(should have tried at least 20mm), and a 50BMG-version is under development. I'm also working on a trumpet design by

expanding a copper tube into a cone. This will require a bit of machining to get the required tools, but should be

worth the effort.

One thing I havent been able to find out is wether or not lead will work as a liner material. I know it's never used

by the pros due to the low melting point, but I havent been able to find out wether or not it will fail completely

or simply be less effective than other materials. Anybody actually tried lead? I'm currently looking into a method

called "lost wax" where a wax mold is cast in plaster and then burned in a furnace to remove the wax, creating a

single-use mold capable of reproducing quite complex shapes. Might be a bit of work, but it sure beats turning out

cones from copper on a lathe. But until I get some data on the usability of lead I really don't want to spend too

much time on this.

Axt - 27-9-2005 at 05:11

Quote:
Originally posted by Fulmen

Greetings everybody.

First off, I really can't understand the reason for using a nasty chemical as sulphuric acid as a sensitizer...

Greetings.

Dont think of it as an ANNM comp rather as "NM/HNO3 dynamite". Sensitising by "activating" the AN is at the expense of density, and doesn't provide the intimacy of two liquids. At least that was the reasoning behind adding sulphuric acid, and I think it works.
Quote:
A jacket from a cal.30 FMJ placed in a 30-06 case with Comp C (appr. 3.5g) easily penetrated 12mm of mild steel (should have tried at least 20mm), and a 50BMG-version is under development.

A 30cal in a .308 with PETN will penetrate 25mm, but very inconsistantly. Its just too hard to get a consistant explosive density in the tight space between liner and wall. Thats why I went to the hemis of the pistol bullets. Easier to pack and inherently less effected by inconsistant packing density. The smaller the charge is the more obvious errors become.
Quote:
but I havent been able to find out wether or not it will fail completely or simply be less effective than other materials.

Never used lead but it won't completely fail. Heres some velocity & penetratuion figures for Pb liners. Very long standoff was used to take a <a href="http://www.sciencemadness.org/scipics/axt/pbliners2.jpg">flash radiograph of the jets</a>.

<center><img src="http://www.sciencemadness.org/scipics/axt/pbliners.jpg"></center>

Quote:
I'm currently looking into a method called "lost wax" where a wax mold is cast in plaster and then burned in a furnace to remove the wax, creating a single-use mold capable of reproducing quite complex shapes.

I've tried casting a solid Pb cone and electroplating Cu onto it. Which would then have the Pb melted out. Same way some "TMJ" bullets are made. This was before I realised ... just use the friggin' bullets as liners :D

The Cu failed to adhere to the Pb.

<a href="http://www.sciencemadness.org/scipics/axt/bjscpenos.jpg">Heres</a> some better pics of the holes above, with a match for scale.

Fulmen - 27-9-2005 at 08:36

Quote:
Originally posted by Axt
Sensitising by "activating" the AN is at the expense of density, and doesn't provide the intimacy of two liquids. At least that was the reasoning behind adding sulphuric acid, and I think it works.


Increased density is beneficial, didn't think of that. Guess I'll have to give it a shot to see how it works. But other than that, since the activated ANNMXY is cap sensitive I'm not quite sure what the real benefit would be. Next time I'll include a pressed charge to see if increased loading densities affects performance.

Quote:

A 30cal in a .308 with PETN will penetrate 25mm, but very inconsistantly. Its just too hard to get a consistant explosive density in the tight space between liner and wall.


I really didn't have any problems with the loading, i simply filled the case with plastic and pressed the liner in. But I can imagine that a powdery explosive would not work as well. Pistol bullets are also interesting choices, I just felt that the long taper of a rifle bullet would be more effective.
BTW, have you tried using a rifle case as a cylindrical liner? a 223 in a magnum case seems like an interesting design.

Quote:

Never used lead but it won't completely fail. Heres some velocity & penetratuion figures for Pb liners


Thank you very much, I'll have to stydy this a bit to see wether or not it's worth the effort.

I've attached a pic if the charge and the result, you can see that the charge wasn't properly centered on the target. It also looks like the jet went a little to the side, I really should have used a rig of some sort to ensure that the liner was perfectly centered. I have two more of these, I'll report back on the result.

Liner.jpg - 202kB

CD-ROM-LAUFWERK - 27-9-2005 at 09:53

Axt and Fulmen, how do u do such ''perfect'' liners?
cant u give us ''newbies'' or ''low-equipment'' guys a good instruction how to make a (working) shaped charge, as small as possible (<1cm CD)?
and (if possible) with pictures?
every shaped charge i made was just a flop... there was NO penetration, not a single mm :(

Fulmen - 27-9-2005 at 10:28

Well, here's a drawing of the charge I mentioned in my previous post. The case is a spent 30-06 (a 308 should work just as well), the liner is the jacket from a 147grs FMJ.

Explosive was Comp C (RDX + 10% heavy oil) and standoff 20mm.

Liner-model.jpg - 77kB

Axt - 27-9-2005 at 19:52

I prefered to use the neck of the case to hold the liner, as its designed to do. No problems with aligning the liner centre, and the neck becomes the standoff so the liner is held firmly against the target on detonation. Though I can see how charging the case with explosive would be easier by going from the other end.

Liquids would be easier but NG wont fire satisfactorily in such small quantities, a thin past thats extruded out the the back when the liner is inserted may be the best charging technique.

Picture repost:

<center><img src="http://www.sciencemadness.org/scipics/axt/bjsc-308.jpg"></center>

In this case it was a .303 fmj (180gr?) in a .308 case, and a 50gr in .22 K-hornet.

Buy some ring magnets and glue them around the case, easy fitting to target :P

[Edited on 28-9-2005 by Axt]

CD-ROM-LAUFWERK - 28-9-2005 at 03:34

thank you guys, but where can i get hollow bullets??
i dont think that it is the easyst to get some ammunition in germany.... :(
wicked!
i need liners :mad:

[Edited on 28-9-2005 by CD-ROM-LAUFWERK]

Fulmen - 28-9-2005 at 09:19

Quote:
Originally posted by CD-ROM-LAUFWERK
thank you guys, but where can i get hollow bullets?


Melt the lead out of the bullet. Don't know how it's done in Germany, but it should be possible to buy reloading components like bullets and cases without any permits. Just say you want to make some dummy rounds for display purposes.

Fulmen - 28-9-2005 at 09:28

Easy loading was an important reason for my method, in addition the performance should be better since the effective length of the liner is greater. But it does require a steady hand or prefferably a guide of some sort to center the liner.
As for the standoff, I simply use three long screws taped to the shell, this makes it easy to fine-tune the legs to make it stand straight.

Standoff.jpg - 62kB

Axt - 28-9-2005 at 21:08

The .45 with magnet. These hold 2.5g PETN/NG, the .357 holds 1.3g. Standoff is provided by straight section of bullet, so it rests directly on the target. I typically dont use electric dets, Its perfectly legal for me to use fuse initiated SC's, not electrical ones, but they do look cooler :cool:

Anyhow, now that I see this is a competition to see who makes the nicest looking ones :P

<center><img src="http://www.sciencemadness.org/scipics/axt/magnet-charge.jpg"></center>

[Edited on 29-9-2005 by Axt]

Fulmen - 30-9-2005 at 02:15

Raising the stakes, are we? Well, you've got yourself a deal buddy. May the best man win :-)

FPMAGEL - 6-10-2005 at 01:33

"Anyhow, now that I see this is a competition to see who makes the nicest looking ones", you meaning design or pics.

Hi you old folk, i've been working on high tensile penatration test and got some good results with petn, but i can't reach a depth of 3cm. Ji thinks the copper sheet is to thick for a standed fillar charge. Any one got some infomation or experience with more than 3cm, thanks.

Axt - 6-10-2005 at 06:34

Quote:
Originally posted by FPMAGEL
you meaning design or pics.

I was joking. Anyone can draw a picture but making one thats functional & practical is something else.

The rest of your ambiguous post makes no sense through lack of information. Same goes for your other incomprehensible posts today. Try making sense and putting it in some form of context :mad:

<i>"3cm"</i> with what? who the hell is <i>"Ji"</i>?, <i>"too thick"</i> is how thick?, <i>"standard filler charge"</i> umm yeh that means nothing to us.

It doesnt take much of a SC to penetrate 3cm, even the tiny ones above approach or surpass that. The glass liner I posted before (first page) pushed through and beyond 5cm.

Does size matter?

Fulmen - 12-10-2005 at 10:52

Me thinks it does. Forgot to mention it earlier, but I happen to have this little beauty lying about. It's an 76mm copper cone from a FFV552 trainer round for the 84mm Carl Gustav, complete with the dummy explosive charge taken from the round.

Now all I need is 500g of RDX to set it off :-)

552-liner.jpg - 83kB

Axt - 13-10-2005 at 19:38

Heh, yes. Size matter if one has the balls to set it off. I've been looking for an excuse to use one of these, foot wide hemispherical liner derived from a copper egg beating bowl.

<center><img src="http://www.thebaytree.com.au/New%20site/images/imgbakew/bowls/coppereggwhite250.jpg"></center>

Fulmen - 13-10-2005 at 23:49

Axt, you know you're insane?

BTW, let me know when&where this will be set off so I can be there :-)


--
There's a fine line between genious and insanity. You're it! -Close personal friend of mine.


[Edited on 14-10-2005 by Fulmen]

FPMAGEL - 21-10-2005 at 01:49

"Well, here's a drawing of the charge I mentioned in my previous post. The case is a spent 30-06 (a 308 should work just as well), the liner is the jacket from a 147grs FMJ. Explosive was Comp C (RDX + 10% heavy oil) and standoff 20mm. "
To improve that don't make the liner so deep.

A test if the plate that has a hole in it is has a nice cut hole and flat, that was a good SC, if it is dented then it relied to heavyly on mass and speed not enought on heat.

""3cm" with what? who the hell is "Ji"?, "too thick" is how thick?, "standard filler charge" umm yeh that means nothing to us. "
fillar charge, something 5000ms+ det velocity. I was talking about Jim, sorry. Just thought people could help with the none usual stuff.

AXT that picture didn't have a good charge, it should have a nice cut, it relied on the liner speed to cut, you need the liner to heat up to 3000C or close to, that liner was still solid all over, you need the edges plasma, and the middle solid




[Edited on 21-10-2005 by FPMAGEL]

Joeychemist - 21-10-2005 at 02:28

Sorry to rain on your little parade, but you have no idea what you are talking about :P

It has been proven that the average temperatures of copper liners when fired with HEs like PETN or RDX are usually between 400-500 C. Never, even close to 3000 C. Shape charges do not “heat up to 3000C or close to” to “cut” through metal. I strongly suggest you read up on the phenomenon which is “the Munroe Effect”.

FPMAGEL - 21-10-2005 at 02:51

Can a copper jacket bullet peice a bullet proof vest. No damn i guess because of a hardness material, interlaced with high tensile strength. Ok can you please explain why. My reason, kintic energy(speed,mass)= heat, hardness of liner on Tank armour, .Pleasesss

[Edited on 21-10-2005 by FPMAGEL]

FPMAGEL - 21-10-2005 at 03:02

". I strongly suggest you read up on the phenomenon which is “the Munroe Effect”."
Thats a fucking HEAT charges not a shape charges.

Axt - 21-10-2005 at 04:14

FPMAGEL, did what I say before come across as an insult? Good, it was meant to but you certainly learn nothing from it. Its not hard to pick someone who likes to pretend he knows more then he does. It irritates me when people post erraneous informaton when they know themselves that they dont know what they are talking about, who are you trying to fool?

Start at the beginning of this thread and read. Everything you have said is wrong. I've posted direct references to studies on jet temperatures of copper liners.

Sorry dude, HEAT as in "high explosive antitank" are typically a shaped charge utilising the munroe effect. Why didn't you look up "munroe effect" on google before posting, its really that simple :mad:

FPMAGEL - 21-10-2005 at 13:42

http://en.wikipedia.org/wiki/Munroe_effect
"Explosive energy is released directly away from (normal to) the surface of an explosive, so shaping the explosive will concentrate the explosive energy in the void. If the void is properly shaped (usually conically), a high-velocity jet of plasma will form."
but in this thread they say it doesn't, not to be offisive but i just don't know what to think from this thread.

http://en.wikipedia.org/wiki/Shaped_charge
yeah nothing new.

[Edited on 21-10-2005 by FPMAGEL]

FPMAGEL - 21-10-2005 at 14:09

Anthing wrong with this explaintion

sh..png - 307kB

Chris The Great - 21-10-2005 at 16:55

Quote:
The enormous pressures generated cause the target material to yield and flow plastically. A common misconception is that the penetration is a result of melting, but both jet and target usually remain in a solid state.


Anyway, wiki is not as reliable as research documents. Everything you claim has already been covered and has been proven flase numerous times by said sciencetific documents.

FPMAGEL - 21-10-2005 at 17:33

"Start at the beginning of this thread and read. Everything you have said is wrong. I've posted direct references to studies on jet temperatures of copper liners. "
And i didn't say that the whole liner is plasma, the liner can be 500C, but the edges(10th mm) can 1000C, and its the leading edges of the liner that touch the traget first.

"munroe effect" i read a coulpe of sources,still don't understand, is it that a vacum speeds up the explosive gases like with nuke warheads designs, or that pan cake/rod thing i was talking about early

[Edited on 22-10-2005 by FPMAGEL]

Axt - 21-10-2005 at 17:44

Yes, this argument has already been made in this thread. The temperature studies I gave on the second page are detecting the surface temperature of the jets, thus the "vapour skin" is false. The pressures generated are massive (in the order of 1 million atmospheres) since this is far higher then the yield strength of copper (1500 atm) and steel (10000 atm)the liner will flow as a liquid, but it isnt liquid. A glacier flows as a river, because of high pressures!

FPMAGEL - 21-10-2005 at 19:43

Thank you, i understood that.

Wall Strength

MephistosMinion - 22-10-2005 at 22:53

How drastically does teh strength of the SC casing effect the penetrating power of the device? Would there be a huge difference between say PVC and steel casings?

Axt - 23-10-2005 at 02:11

See attachment. In summary, yes the thicker the casing the better but overall the added weight makes for a less efficient charge, gram for gram the light containment will penetrate further but gram for gram of <i>explosive</i> the heavy containment will penetrate further.

What this actual gain is, as a percentage isn't mentioned.

Also with thick containment the liner should be held as firm as the body, no point constructing a SC out of 5mm steel pipe and then sticky taping the liner in.

[Edited on 25-10-2005 by Axt]

sc-confinement.jpg - 221kB

MephistosMinion - 24-10-2005 at 00:18

Thankyou for the reference Axt. How would you suggest attatching teh liner into the pipe without malformation of the jet occuring?
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