Unconventional Shaped Charges

Nice test Nux, but damn plate, we still don't know where your charge stands on the graph because one of the welds broke which would have affected the jets performance I'm guessing. Even though it broke you still got more depth so it can go deeper.
Just goes to show how much energy these jets carry if they can break the welds that they don't even contact

For a charge 3x standoff and 4 CD penetration, it stands around non-precision line at the moment but I think you could get over it if the plates didn't break apart at the weld.


[Edited on 18-9-2015 by greenlight]

Where all the plates welded together?
If so, did it break all the welds between the plates?

All 5 plates were tacked welded on 4 corners so it broke 18 tacks in total,where the carrot pokes through it only broke 2 tacks so 4x4= 16+2=18 a lot of tacks anyway.

[Edited on 18-9-2015 by nux vomica]

Quote: Originally posted by gnitseretni

Very nice! I would increase standoff even more. That first hole is pretty big. It takes a lot of energy to punch a hole that size. If you increase standoff, you'll reduce the size of that initial hole and you'll have more energy available for penetration.

Quote: Originally posted by greenlight

Very interesting, do you have a density measurement for the plastic explosive mix you are using at the moment for that charge?

Quote: Originally posted by nux vomica

Its 1.26 grams per cubic centermeter greenlight

Unfortunately after checking my etn plastic my earlier post was the wrong density measurement I mismeasured the aluminium tube dia and being a small dia and etn weight it made a large difference to the result.

I remade my density measuring tool to measure 10 grams, I reamed a 20mm hole in some delrin and made a base and plunger to suit it and found it actually measured 1.417 grms cm3 density .

The etn plastic pellet measures 20 mm dia by 22.46 long so 3.141 x sqr10 x 22.46 = 7.056 cm3
10 grams / 7.056 cm3 = 1.417grms cm3

So it seems my etn plastic is a reasonable density for shaped charges after all, nux





[Edited on 22-9-2015 by nux vomica]

Russian RPG 7 vs 16 inches bullet proof glass

More kinematics

Quote: Originally posted by nux vomica

Franklyn you got me looking on the tube this one was impressive as well. nux https://youtu.be/q6j9wEF1sf8 i love that video, but its not a normal tandem shaped charge as the title says (afaik) , its an anti structure warhead - first one is a shapedcharge and the other detonation is a electronic delayed HE-Frag... just sayin

@ Nux: Did you spin those liners on a lathe? Brings back good memories.


[Edited on 1-10-2015 by nitro-genes]

Attempted penetration of a 19mm steel plate with a new batch of plastic explosive but no good effect.
EFP was 30mm diameter 60 cm standoff and 17 g charge weight.
Only 12 mm penetration. I even placed some ballistics gel behind the plate to see effects on the other side

I think it is bad plastic because I added the PETN/acetone mix too fast to ice water whereas I usually add slowly. The fast addition resulted in still a fluffy non-granular product which didn't roll easily. This meant I used more binder/plasticizer which has affected VOD quite badly. There is a visible flame for a second during detonation that is not usually there.
I rolled 150 grams too which is a shame, maybe I can use it to attempt to catch the EFP slug in the next test as it looks like it is still forming the slug okay.


[Edited on 1-10-2015 by greenlight]



[Edited on 1-10-2015 by greenlight]



[Edited on 1-10-2015 by greenlight]

Quote: Originally posted by nitro-genes

@ Nux: Did you spin those liners on a lathe? Brings back good memories.

Have you considered making the projectile like a spear? This is achieved by placing a metal cross across the back of the copper platter. There are patents which detAil his the elongated spear is made and this would probably help the penetration greatly. This is a tantalum liner and they have worked out how to catch them intact somehow

I know that curvature of the liner and the head height of the explosive affect the elongation of the liner. I think I am getting quite wide slugs instead of more elongated shaped because the explosive height in the charge above the liner is only .75 the diameter of the liner. This is because of the density of the PE though its rollled for several hours to about 1.45-1.49.

This metal cross idea sounds interesting. I will look for patents documenting it if it too affects the elongation of the liner it could be useful. I always thought altering the back of the liner having it thicker in parts would make it break up when subjected to a detonation wave.
The projectile in the picture you just uploaded is the perfect shape for penetration and is the most well-formed I have ever seen. I wonder how they caught it in that state


[Edited on 2-10-2015 by greenlight]

[Edited on 2-10-2015 by greenlight]

Patent : 5365852 How to create an EFP with fins.
A thin cross shaped foil between the liner and explosives.
The patent does not tell what the foil is made of, but it says about 25% of the liners thickness.

Why do they not specify what the liner material or foil cross is made out of?

Something like this Tantalum foil maybe?

http://www.ebay.com/itm/10-gram-0-35-oz-99-98-Pure-TANTALUM-...

[Edited on 4-10-2015 by greenlight]

Here's some pics from a recent test on another successful small scale EFP on steel target.
The diameter was 14mm and this time a metal casing was used for stronger confinement.
Charge was 7.5 grams PETN/RDX/plasticizer-binder and explosive head height ended up being 2x the diameter of the liner which is the highest I have ever had.
Target was 6mm thick square of steel and standoff was 30 cm.
It has made a clean 9x9mm hole and unusually another smaller hole directly above that looks like liner breakup but has formed another round hole. Two for one deal

[Edited on 5-10-2015 by greenlight]



[Edited on 5-10-2015 by greenlight]



[Edited on 5-10-2015 by greenlight]



[Edited on 5-10-2015 by greenlight]

Just came back from testing a new batch of PE using the usual 30mm EFP on steel.
Target was 10mm steel again but this time a slab of remelted (not as clear as fresh stuff) ballistics gel was placed behind to give a rough idea of what happens behind the target.
Charge weight was 17 g which was enough to punch a nice 19mm diameter hole and push through the ballistic gel as well,
Standoff was 60cm.

It seems that as soon as the slug hits flesh like material at a lower velocity it fragments into wide wound channels of varying size. Some of the stray copper pieces separated inside the gel so much that the width of damage by the fragments is around 100mm diameter.
After the ballistic gel was cut along the wound channel lines, it was dissolved in boiling water leaving the copper fragments which are also pictured after being recovered. A lot of copper powder was also found lining the channels in the gel which gives them a brown colour.
I will use fresh ballistics gel next time but that test is enough to confirm that it would not be good at all to be in the firing line of one of these even if your behind a steel target.

[Edited on 16-10-2015 by greenlight]



[Edited on 16-10-2015 by greenlight]



[Edited on 16-10-2015 by greenlight]

EFP

If you have a metal detector, maybe straight up on a windless day would work, assuming the projectile follows a reasonably stable trajectory in the air What goes up...

[Edited on 10-11-2015 by nitro-genes]

Shoot vertically into the air is a good idea. The epicenter may be buried EFP. So 50 centimeters below ground, I think the sand around the EFP. Established perpendicular to the pipe, and 1 meter long for the spirit level. No wind at night (often). Another thing. The space can be a grassy field. Meadow. The grass is laid microtene film. On average, about 8 meters bags, thus the radius of 4 meters. Microtene is rustling material. Will hear the impact. The impact liner may be expected in about 60 seconds. This is only a guess. Perhaps it is calculated. (it's all nonsense, nothing is returned...)
Liptakov

First conical CSC bad time

Had a first attempt at a conical shaped charge courtesy of Nux vomica's cones today but with a bad end result.

Copper cone was 18 mm diameter and 42 degrees and charge casing was steel tube.
Charge was 10 grams PETN PE and was 2x cone diameter in head height.
Target was a 90mm thick steel cylinder and standoff used was 3.5x cone diameter.

There is a 15.5mm deep hole and it appears most of the copper is splattered around the area of entry not directed inside it like it should be.
I think the most likely cause is too much explosive behind the cone. I have one more cone and I think I will try 5-7 grams next time and hopefully get a better result.


[Edited on 18-11-2015 by greenlight]

Shaped charges are pretty finicky, photo's look familiar. In case of unsymmetrical liner splatter, it is most likely due to a prematurely disrupted jet due to either an asymmetrical liner, or non-homogenous explosive loading (air cavities). These are absolutely the most important factors determining clean jet formation. For this reason, either liquid explosives or very homogeneous plastiques (containing enough plasticiser to fill all air spaces) are best, an other option is pressing.

Wall thickness of the liner is much less important for clean jet formation. Very thick liners generally produce a well formed jet, but with lower velocity, thus penetrating less deep. Extremely thick liners, and/or driven by a relatively slow explosive can even lead to a completely "filled" jet canal, filled with liner material. In one occasion, firing a steel hemisphere (7% of CD liner thickness using an AN/NM/NC plastique left the carrot sticking out of the target plate, but no splatter at the sides was present. Should still have the picture of that somewhere. Very cool to see a steel carrot welded seamlessly into place into solid 5 cm steel. I contemplated it might even have some applications, similar to explosive welding. With some shaped charge explosive modelling, it may be possible to "shoot" predefined structures into very thick steelplate material, where welding might be impossible. Like sort of a nailgun on steroids, though not very practical probably in real life.

Supersonic liner wall jets ( from very thin liners) look like more broad homogenous splatter. Det or liner offsets produce more of 1 sided elongated penetrations, and a curved jet (picture posted by Axt in the beginning of this thread somewhere).

[Edited on 19-11-2015 by nitro-genes]

Second attempt with a conical liner shows an improvement with penetration but nothing like it should be.

This time I pressed the plastic explosive in small increments around the cone with a thin piece of metal and pressed the whole charge as hard as I could with a metal rod to make sure there were no air gaps. Charge weight was 6 grams this time and the detonator was centered just pressed about 2-3mm into the main charge.
Target was a 75mm wide piece of steel.
Result is a cleaner hole than last time but it still looks like there is a bit of spalling around it. I placed a video camera near the charge and can see what looks like a smoke ring coming out from the top right after detonation which I thought was a sign of a good shaped charge.
I can stick a small metal rod about 30mm into the cavity but I think the carrot is blocking the rest. Is there any way to cut this down the jet path more delicately than using an angle grinder to find out?


[Edited on 20-11-2015 by greenlight]

I also have headache when i deal with NG but a strong coffee should fix it.

Shaped charges need at least 6500 m/s VoD to work fine. I am sure that PETN and NG would be more than sufficient. NG will fill the air gaps and you won't need to press very hard as you did before.

Good luck and waiting for your results

The PETN is pushing a little over 7000m/s so that would be efficient in SC but I might stock up on the coffee and make a batch of NG if I come across any more copper cones

[Edited on 21-11-2015 by greenlight]

Quote: Originally posted by greenlight

The PETN is pushing a little over 7000m/s so that would be efficient in SC but I might stock up on the coffee and make a batch of NG if I come across any more copper cones

Quote: Originally posted by pm1306

Has anyone tried firing an EFP through a (plastic) container of gasoline or kerosene from a distance? The friction of the copper slug passing through the fuel at supersonic speed should generate sufficient heat to ignite it but I would be interested to know if that is true in practice. The auto ignition temperature of gasoline is between 247 and 280 degrees according to Wikipedia. Kerosene is lower at around 210 degrees C. I would like to know the results for both. According to Mythbusters episode 15 a standard bullet fired through gasoline does not ignite it. According to https://en.wikipedia.org/wiki/Shaped_charge the temperature of the jet in a standard (conical) shaped charge is over 400 degrees C which in itself should be sufficient to ignite the fuel on contact. Use of a plastic container would ensure that the ignition was not caused by the heat or possible spark caused by the slug hitting a steel container. The distance should be sufficient to eliminate the ignition being caused by the explosion itself. (eg. 10m) I would also be interested in the effect of firing from close range (eg. 300mm) so the explosion itself does ignite the fuel, possibly using ETN which has a positive oxygen balance. (TATP would be no good as it is endothermic.) In particular I would be interested to know whether the slug disperses the fuel sufficiently before detonation to generate a thermobaric explosion or merely a deflagration. If possible a video of the result would be great. (I am not into experimenting with these things myself and would prefer to leave it to those with more experience.)

Quote: Originally posted by greenlight

Yes, I agree, fuel will just be dispersed upon impact. I think the only way is with a Mg liner. I have a 30mm one here that weighs 1.28 grams and is 1mm thick. I might give it a go when I have some spare explosive. BTW, nice animation of jet formation from RPG.

I think RPG use TNT as EM and the liner doesn't look like cone , it has some bends in the side. The detonator is place in a deeper way.
have a look here and tell me what you see :


Most of the books talk about Pentolite(50% PETN and 50% TNT) as the most used EM for shaped charges.

Thanks for the info.
the head of the cone is not sharp angle but flat ! is this a mistake in the figures?

@Greenlight,

I think your setup is similar to this one. I see the figure use booster(Tetryl) and it has wide area. Maybe to make the wave very flat?

I think melting ETN would be very dangerous process


[Edited on 2-12-2015 by ecos]

I was watching a video for Kornet-E : https://www.youtube.com/watch?v=bPjI1YNi4uc

I noticed it has two shaped charges. The first one destroy the active armor while the second one penetrates the shield.

The first cone doesn't have enough EM over the cone head (~1.5X). I don't think this would have enough power to convert the cone to carrot shape !

The second cone is large. There is some between the cone and the detonator that I don't know.any idea?


Its penetration power exceed 1200mm into steel . This is massive power to be achieved with both cones !!!
where does this power came from ?



I thought the explosion of the first cone would effect the whole system but it surprise me that the second cone is able to do its work after this explosion.
how can this happen ?

I found this also:

http://www.military-today.com/missiles/kornet_t.htm

It says total missile weight is 27 kg and warhead (explosive) weight is 7 and 10 kg.
It is quite hard to find accurate information on it.

Also, yes, I realize what I said sounded a little stupid when talking about energetic materials which detonate at thousandths of a second
I am unsure how the front detonation does not affect or damage the initiation system for the rear shaped charge as I just remembered a video on Youtube of a Carl Gustav warhead penetrating a brick wall with the first charge, flying through this hole and detonating the secondary charge on the other side.
I will look into it as I am interested in finding out now as well.

yes, it sounds interesting.

I understand from your webpage that , 27 Kg is the weight of launcher + warhead and the 7kg or 10kg are the warhead's weight.

27 kg is too much for a warhead.

I checked the penetration power of Panzerschreck. It has 700 gm of EM (60% RDX and 40% TNT) and it can penetrate 21 cm of steel.



so it is still strange for me the superior power of Kornet-E (1200 mm ) !!!!



[Edited on 28-12-2015 by ecos]

Quote: Originally posted by ecos

Panzerschreck vs Kornet-E

Quote: Originally posted by ecos

@Fulmen, The technology of cars has changed a lot specially the design of motors and safety but the SC didn't change this much. Most of the effort was consumed in understanding how it works. I also believe most of the new changes was to improve the penetration power but most of the improvements has minor effects. The concept in SC is EM and copper cone. most of the studies were about the suitable EM and different cones shapes or materials but the concept is the same ! Panzerschreck --> 700 g penetrates 21 cms. Korent = ? g penetrates 120 cm therefore , Power of Kornet-E = 5.7 power of Panzerschreck If we assume linear equation this means the SC of Kornet should be 5.7 times the size/weight of Panzerschreck = 5.7 * 700g = 4 Kg of EM if the warhead is 10 kg (4Kg for shaped charges , 6 kg for propallent , frame , fins, ...) this would make sense for me

Quote: Originally posted by PHILOU Zrealone

For a given explosive, the increase of explosion power is quadratic as a function of weight, not linear! EP = A*(weight)² A being a constant dependant of the geometry of the explosive charge, density of it and of the explosive itself... This effect is obvious when plotting lead block test expansion as a function of weight of explosive for various explosives...

Plate dent, leadblock expansion/compression and sand crush test are somewhat crude tests indeed, all measuring different aspects of "explosive power". Lead block expansion is probably the best in estimating total energy output, but likely least effective in predicting shaped charge performance. Plate acceleration in an infinitely large absolute vacuum would come close I think, but if the plate thickness and weight would approach zero, you would probably only find the VoD.

[Edited on 30-12-2015 by nitro-genes]

Quote: Originally posted by careysub

Quote: Originally posted by PHILOU Zrealone   For a given explosive, the increase of explosion power is quadratic as a function of weight, not linear! EP = A*(weight)² A being a constant dependant of the geometry of the explosive charge, density of it and of the explosive itself... This effect is obvious when plotting lead block test expansion as a function of weight of explosive for various explosives... Assuming the stated lead block test results are as you say (I have not tried to check - I would appreciate a link if you have one), then this is true only if "explosion power" is a term defined by the lead block test results, which out of necessity only deals with small amounts of explosives. Under such conditions non-linear effects with energy dissipation mechanisms, edge effects, detonation build-up, material yield properties, etc. are quite plausible. With the advent of sophisticated numerical modeling techniques for explosives, and much more detailed understanding of the fundamental thermodynamic and other physical properties of explosives, it is apparent the simple lab tests like lead block expansion, sand crush, etc. are quite crude (but far from useless) at characterizing explosive performance. But the total energy in the explosion is absolutely linear in the amount of explosive employed. [Edited on 30-12-2015 by careysub]

There is a graph somewhere (I can't get my hand on it) that displays the explosive power of Triazido-trinitrobenzene vs other primaries as a function of weight and resulting sand crushed...
There you see it is quadratic.

There is also that very interesting document I requested in document request and translations (9) the document was provided by Boffis and by Solo a little later.

If you plot those datas Inside excel and that you do a little maths you get this: I'm stil working on those fabulous datas!



This is fabulous because:
1°)if you know this, you will be able to compare all explosives vs each other by weight but also by volume simply by knowing their parameters A and B:
LBT= A*x² + B
A is dependant of the geometry of the Lead Block Test, B is dependant of the detonator power and of sensitivity of the explosive material to initiation.
The volumic power is something that link many explosives under general rules...at first I have made assumptions by simple linear extrapolations...but this precise quadratic dependance is very interesting to get precise predictive datas.

2°)Considering the usual cylindrical Lead Block Test single point with help of those spherical LBT datas, one can convert the single point info into a precise extrapolated curve. Indeed one will easily find back A and B for the conventional cyclindrical LBT for all given explosive (Medina; TNT; RDX; Tetryl; HMX) and then for all explosives tested by the single point cylindrical LBT.

3°)The Lead block Test is biased by the use of a detonator...if the Lead Block Test was made with pure explosive D2D then the very important point 0 cm³ for 0 gr explosive(common for all explosives could be used)!
Of course the use of primaries as initial study case will be very important because they detonate from flame in minute amounts and they will give the idea on how explosive behave in large amount under self propagating detonation. Below a certain weight no detonation is observed and the quadratic dependance is not observed but at a certain weight its expansion will be exponential until it reaches the quadratic curve.

4°)I have a lot of lead at home, the spherical design allows one to use much less lead than for a cylinder...also knowing that you can play with mini-sphere is very interesting for amateur experimentalists like us...we could then provide interesting LBT datas with less lead and less explosive...
This is of course also of interest to scientist who have little explosive material under hand to test or who don't have the possibility to cast and manipulate large LBT (can be very heavy and energy consuming)!

[Edited on 1-1-2016 by PHILOU Zrealone]
Here is also a proof about the effect of the detonator...sadly I don't have its origin because it is saved image from a post of another user...


[Edited on 1-1-2016 by PHILOU Zrealone]

Quote: Originally posted by ecos

@PHILOU Zrealone, Let me help you , the last image in your post is from : Nitroglycerine and Nitroglycerine Explosives by Phokion Naoum You can avoid the effect of detonator by adding metal oxide powder. this will avoid the low velocity detonation by increasing the speed of detonation wave inside the EM The attached patent deal with the probs but the sensitivity will be increased for the Gelatine Note: the link in your post is not working !

Thank you for the picture lost reference.

Interesting effect of Metal oxydes and Metals indeed!
This effect, if real, should be visible with the Lead block test...since a higher VOD will display more deformation energy.

My link does works for me with "Internet Explorer" and with "Google Chrome" navigators...
Anyway, you could do a fast search with the search tool of the forum into the reference folder 9 under poster PHILOU Zrealone with key word Lead Block Test

Quote: Originally posted by nitro-genes

Did they correct for the amount of volume in the sphere? If the wallthickness of the sphere decreases due to a larger cavity with increasing explosive amount, then the energy is of course increasingly more efficiently transferred to aid expansion. There probably is a large database having all these test data for a large number of known explosives. Wondered if it would be interesting to put them all in a statistical model and look at correlations and interactions between various physical properties. Most likely however, many of the test results would show strong correlations with many factors but also interactions, which would limit it's use to make ab inito predictions, even more so since the conditions of the test itself probably interact somewhat with the explosive used to determine the outcome. All explosive properties like density, VoD, energy released, volume and nature of gasses produced, etc will interact not only with each other, but also with the test itself. Even with a very large dataset and all tests performed under the most rigorously controlled conditions, there would be far to many factors to separate to come to a robust predictive model IMO. Although not directly related to your post, similar things might happen when comparing primaries using LBT, a big confounder here would be the acceleration of the detonation wave, which is much faster for azides for example then for DDNP. It would be interesting to see whether small scale LBT for primaries like you desribe indeed would be a good predictor of "initiation potential". [Edited on 2-1-2016 by nitro-genes]

Very interesting point of view and debate

Have you downloaded the document from my link?
It is wel expressed...the dimensions of the sphrere LBT are identical to classical cylindrical LBT, except it is spherical...so the inner cylinder to place the charge is 100% identical.

The sphere is inscriptible inside the cylinder...so both display the same diameter.
From what I have seen the difference in LBT expansion is almost the same.

[Edited on 2-1-2016 by PHILOU Zrealone]

Quote: Originally posted by PHILOU Zrealone

Interesting effect of Metal oxydes and Metals indeed! This effect, if real, should be visible with the Lead block test...since a higher VOD will display more deformation energy.

Quote: Originally posted by nitro-genes

Hi Philou, The link didn't seem to work here too, found It by using the search engine like you suggested. I was merely guessing about the cause of the observed non-linearity in the graph you posted. Pretty clever using a spherical block to prevent cracking. [Edited on 5-1-2016 by nitro-genes]

Quote: Originally posted by ecos

Quote: Originally posted by PHILOU Zrealone   Interesting effect of Metal oxydes and Metals indeed! This effect, if real, should be visible with the Lead block test...since a higher VOD will display more deformation energy. as i understand, the LBT doesn't take into consideration the effect of the detonator. With different cap number we should have different Trauzl number. I think this effect is for nitric esters only. From Wiki , NG has higher Trauzl number than HMX, while HMX has higher VoD than NG !however the most important thing in SC is the VoD. The higher is the better. I didn't get your point of mentioning the LBT in this thread. I am really sorry if i got lost. I am also interested about this effect of adding metal oxides to accelerate the detonation wave inside EM. do you know any analytical way to calculate it ? I don't think the patent is mistaken .

You wrote:
"If we assume linear equation this means the SC of Kornet should be 5.7 times the size/weight of Panzerschreck = 5.7 * 700g = 4 Kg of EM"
I expressed that the dependance is not linear but quadratic...and that's why I went to LBT...

LBT is a mix of many parameters, heat of explosion, volume of gases, VOD, pressure...it is correlated to p*V=n*R*T equation and reflects thus the total work p*V (energy output).

I'll open a specific tread about LBT

Quote: Originally posted by PHILOU Zrealone

I expressed that the dependance is not linear but quadratic.