Unconventional Shaped Charges

Hey check this out. It's rather similar to a shaped charge but it's an Explosively Formed Penetrator! An explosively formed penetrator (EFP), also known as an explosively formed projectile, a self-forging warhead, or a self-forging fragment, is a special type of shaped charge designed to penetrate armour effectively at stand-off distances.

Here's the description: A conventional shaped charge generally has a conical metal liner that projects a hypervelocity jet of metal able to penetrate to great depths into steel armour; however, in travel over some distance the jet breaks up along its length into particles that drift out of alignment, greatly diminishing its effectiveness at a distance.

Whereas for the EFP, on the other hand, has a liner in the shape of a shallow dish.The force of the blast molds the copper plate into any of a number of configurations, depending on how the plate is formed and how the explosive is detonated. Sophisticated EFP warheads have multiple detonators that can be fired in different arrangements causing different types of waveform in the explosive, resulting in either a long-rod penetrator, an aerodynamic slug projectile or multiple high-velocity fragments. A less sophisticated approach for changing the formation of an EFP is the use of wire-mesh in front of the liner: with the mesh in place the liner will fragment into multiple penetrators.

As a rule of thumb, an EFP will perforate a thickness of armour equal to only about the diameter of its charge, whereas a typical shaped charge will go through six or more diameters.

[Edited on 16-7-2007 by tito-o-mac]

Formation of Explosively Formed Penetrator. here's a short clip: http://www.youtube.com/watch?v=JfCCXglrJuo


[Edited on 16-7-2007 by tito-o-mac]

Hi there.
I'm allways on this kind of penetrator, i have done also some tries with them.

The very first try wasn't a success, to thin not to blown apart




Target was a 5mm thick steel plate.

The second attempt wasn't a success too.




At this time, i think, the liner was to thick.

So my next project is with this liner.
2mm thick
50mm diameter
made from copper



hope getting better results with this one.

So long, hope you understand what i wanna tell you
Greetings from Germany.

MRUD

Can you explain more about picture 3 from top?

Do you have any measurment of the penetration? Anyway, just wanted to ask you something: when the explosives were detonated, did the container produce any shrapnel or stay intact? One more thing: the range from which you fire from will affect the shape of the charge, also the penetration. Too close and immature formation of the charge will reduce the penetration!

Here's a suggestion: A less sophisticated approach for changing the formation of an EFP is the use of wire-mesh in front of the liner: with the mesh in place the liner will fragment into multiple penetrators. Also use aluminium for greater penertration against concrete targets.

BTW remeber to show us your pics ( and if maybe a video)
Anyway all the best

The charges are generally cylindrical, fabricated from commonly available metal pipe, with the forward end closed by a concave copper or steel disk-shaped liner to create a shaped charge. Explosive is loaded behind the metal liner to fill the pipe. Upon detonation, the explosive projects the liner to form a projectile at a velocity well over 1 km/s, depending on the design and type of explosive used. This slug is projected towards the target at about two kilometres per second. The chief advantage of the EFP over a conventional (e.g., conical) shaped charge is its effectiveness at very great standoffs, equal to hundreds of times the charge's diameter (perhaps a hundred meters for a practical device).

It can travel up to perhaps 1000 charge diameters (CDs) before its velocity becomes ineffective at penetrating armour due to aerodynamic drag, or successfully hitting the target becomes a problem. The impact of a ball or slug EFP normally causes a large-diameter but relatively shallow hole, of, at most, a couple of CDs.

Try to beat the record of 100mm penetration MRUD!!

[Edited on 19-7-2007 by tito-o-mac]

[Edited on 19-7-2007 by tito-o-mac]

Sorry, I was referring to a military build EFP. Remember the very first post the gut used ANNMSA ( I don't know whats that) but I think a Ammonium Nitrate NitroMethane Alumnium (ANNMAL) should also work, cos' its more readily available to obtain and if you do not want to use your PETN

Errr... I'm not too sure about the distance of 10cm. It seems a bit short to me though! One more thing: is the 2 cm liner thick enough to not disintegrate with the force of the explosion? Maybe a thicker liner would work.

Very good job anyway!
Greetings and all the best for the next project!

[Edited on 20-7-2007 by tito-o-mac]

Here we go, EFP mark III.

I think, it's an nice result i got. Not the best, but better than expected

Target was a 5mm thick steel plate, distance to target around 40cm.
Got a nice hole in the plate, and the force was strong enougt to deform the 2cm plate behind.




At the target site


result





Greetings

MRUD

The copper plate was formed with a "matritze" (don't know the english word) a picture will show you, what i mean. He was pressed between this to.


Liner weight was 37g, angle around 30°
And i (wasted) used 56g of PETN at this EFP.

[Edited on 21-11-2007 by franklyn]

Results of a 38mm SC

Here is the result of a 38mm shaped charge,it nearly penetrated 72 mm of mild steel(6x12mm mild steel plates welded together).
The HE in the main charge was about 95g 2:1 MHN/NM gel, density about 1,5 g/cm3. Primary was 0,5g Ag2C2*AgNO3/MHN mixture and 2g MHN.
On the bottom you can see the buckle made by the copper jet. On the first picture you can see the aluminium mandrel on which the copper liner was spun. The copper liner had an thickness of about 0,8-1mm(my copper spun liners don’t have an even thickness) and was parabolic formed. I think the copper colored dent was caused by irregularities in the thickness of the liner and thus irregularities in the copper jet.

[Edited on 31-1-2008 by hinz]

[Edited on 1-2-2008 by hinz]

Pic 2

Nice one, 72 mm of steel is a long way! Could you please try to make a better picture of the formed jet channel? Just hold a strong light source next to the camera to make it better visible...

What was the appearance of the explosive btw? Did al of the MHN dissolve in the NM or was part of the MHN present as a suspension? From what I remember with PETN, only a small part actually dissolves in the NM, although MHN en PETN are not the same of course. But if so, you could improve the results by incorporating 4% of a binder like NC derived from ping pong balls to get a more homogenous explosive composition and achieve better jet formation...

Looks like your carrot was blown off-center resulting in the copper-coloured dent. This can be the result of many things and I noticed it on several occasions as well.

Were the variations in the liner thickness only present as a gradient going from 1 mm at the top of the cone to 0.8 at the base, or did you measure a difference in liner thickness along the base of the cone? The first doesn't harm jet formation and liners having a gradient in thickness from top to base are used in some SC designs. Don't forget to anneal your liner one final time when your finished spinning to remove stress in the metal that can also affect jet formation.

From what I calculated you used about 1 CD head height, (space between aphex of the cone and the detonator) but how long was the detonator and how was it placed? Sticking the detonator in the explosives composition and to make sure it is completely alligned with the longitudanal axis of the liner is nearly impossible. Therefore I normally only let the base of the detonator touch the explosive composition and don't stick it all the way in.

Nice work, keep it up!

[Edited on by nitro-genes]

Here are the close up pictures of the hole, quite difficult to get enough light in it.

You're right, only a small amount of MHN dissolves in the NM actually. I kneaded a bit of the HMN/NM mixture to a piece of coffe filter, so the NM could soak into, and removed it afterwards. As the NM dried, there was only a little bit of MHN left o the paper, visible as a white spot.
I added the NM to the MHN to make it less sentitive, use some of the spare oxygen of MHN and to get the best density out of the HE without pressing it.

The liner thickness variated because the liner was sometimes stopped on the mandrel by the piece of brass and aluminium I uesd to push it onto, so some particles on the mandrel cut into the mandrel as well as into the fresh annealed and soft liner (difference in liner thickness along the base of the cone). This caused the round scratches on the mandrel as you can see in the first pictures. Needless to say that these were also cut into the liner, but fotunately not as deep as in the mandrel.

Yes i used about 1 CD head height, but I didn't measure exactly, I made it mostly "by eye" and after I soldered the liner onto the steel pipe, I poured water into the SC on a scale to get its volume and thus the amount of HE I had to prepare. Standoff was about 2,5 CD BTW.
Detonator was made from a 5ml syringe,plased inthe middle of the SC and sticked trough a plexi-glass plate, it had a diameter of about 13mm, it's too small on the picture, but the liner shape should fit quite well.

The carrot was oddly formed, first it made a big 18mm diameter hole, about 20mm deep in the steel and then continued further 40mm with a small diameter of about 8-4 mm from top to bottom, in the end, the copper colored dent was formed, as the dent lacks from impact craters from small particles.

[Edited on 2-2-2008 by hinz]

Up to 9 CD is possible for a simple 60 deg copper cone, having a uniform thickness of 2% CD in combination with octol (350+kbar). Even with cyclotol (300+ kbar) 8 CD is possible, graph is listed in PATR under "Octol". Constraints are most definitely determined by the precision of charge and liner and the allignment for an amateur charge, and greatly determines the maximum streching ability of the jet. Military liner standards call for deviations no greater than serveral micrometers, which is out of reach for spun formed liners as well (without after-machining IMO). My last charge reached 4.2 CD penetration @ 3-4 CD standoff, but liner was spun from 1mm thick copper giving 0.8 mm wallthickness on average. (2.5 % of CD). I've made another liner with a wall thickness of ~0.6mm (1.9% CD) and could possible reach slightly deeper penetration, though 5 CD will be the absolute limit IMO...

Highest numbers I'm aware of were 10-11 CD for molybdenum trumpets and 12 CD using a hemisperical DU liner IIRC...

[Edited on by nitro-genes]

NM/TNP- SCs

aha, that does make it clearer - they are probably supplying the insurgents in Iraq something similar to that which they are supplying to Hiz'bollox in Lebanon, large EFP type projectiles based upon IED's.

http://www.defense-update.com/newscast/0207/news/010207_efp....

http://www.mnf-iraq.com/index.php?option=com_content&tas...

http://www.mnf-iraq.com/index.php?option=com_content&tas...

http://www.globalsecurity.org/military/systems/munitions/bul...

These aren't overly complex, simply a more advanced 'cheap trick', someone with some knowledge has contributed the original design, but after that even 'desert warriors' could acheive a high degree of manufacturing excellence (fucken hell, beat out a shallow copper bowl and mount it backwards).

This picture from Wiki should demonstrate why standoff is essential to the proper utilization of these:

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

Shit happens quick, but it still ain't instantaneous, the penetrator/projectile still needs time and airspace to be explosively forged (the blast / air resistance caves the outer edges back onto the centre - where it forms a fairly well defined slug). Why they don't just setup a small machine shop (there are lathes & mills in Iraq, surely) and machine out or cast & then polish a copper cone and get the improved penetration is probably beyond argument, given the size of the charges they are using, they don't fucking need to.

Im not sure if posting this crosses he line as "practical" Info
Im having a dfficult time wapping my tiny inellect around the subtle apparent differences? But is this is published by Uncle sugar the reprinting of which shouldnt ruffle any feathers as the " (whomever he may be) man" originally OKed the relaese of info.These are the basic dimensons; 2-2.5 in diam. steel pipe and 3-4 in long open at both ends naturally.And finally another pipe,a thin one of copper tubing 1/2-3/4 dia.x
1.5 in long open at both ends.

Expected penetrtion fron this device and a high VOD HE is 1.5
in. depth x 1.5in wide.An approximate 1/4n standoffcapparently produces the best results with this size device. (+1! for yesterdays SCOTUS Heller decision!!)

why not experiment with the glass liners at hand? Ive heard a glass funnel with the spout removed and the resulting small hollow plugged with epoxy etc.or a martini glass or other beverage container with the stem removed can make very good liners. I think only by experimentation will you discover which liner angle will work best with your device.
If Im not mistaken there is a drawing of what appears to be a well thought out device using a 50mm glass funnel as a cone and otc PVC plumbing components in this thread.Besides it wouldnt hurt to read the entire post and then some if your expecting a device that works at all.

A 50 MM glass funnel/with the hole plugged w AL and glue worked well enough for AXT to penetrate 2 in steel witness plate with clean entrance and exit holes.Not bad for an improvised device made from OTC components.

Different Target!

I on the other hand I wonder whats the attraction with LSCs

I dont see what real advantage they have over a tamped line charge or cutting torch.

Each to our interests is what s important I dont dis anyones interest unless it infringes on my own rights or anothers.
Be a real boring,backward, stagnant enviroment if we all had similar interests.If im not mistaken there have been many posts here dealing with all SCs, LSCs included.All ya gotta do is post

Im sorry but the last sentence of your post may reveal why you dont find CSCs interesting there are as many variables in cone SC if not more than LSC designs.

[Edited on 16-2-2009 by grndpndr]

It's not that I'm not interested in CSCs, it's just that this afternoon it suddenly hit me in that all I can do with CSC's is either widen the hole or go deeper(or both but that would require a rather large amount of HE). With CSCs the results are always the same: a hole. Big, small, wide or narrow.. doesn't matter, in the end it's still just a hole. With LSCs you can get a little more creative as to what the result will be, I think.

I'm not arguing, I just hadn't looked at it like that before But the fact that I haven't been able to construct perfect cones probably doesn't help

Ive had no luck with copper cone construction either.But it seems AXTs experince with glass funnels with a thickness of 1mm and seemingly more precise construction than cheap martini glasses would have to be a bit more successful.On the other hand the thickness of the less dense glass would seem to indicate athicker liner is needed to compensate for denser copper.

If size werent a consideration imp steel EFPs offer the most bang per buck if internal damage is a criteria.with 1/2lb he/platter @6100 plus /minus mps AN/NM HE the results of an imp efp from a garge junk pile and equipment are frightening.

Other than linear charges for demolition.perforation of oil field casings and explosive welding i cant think of any commercial applications where HEs are precise enough.
All extremely important in thier own right but i think w/o the most recent, explosive welding of dissimilar steels there wouldnt be composite armor for tanks capable of resisting atgms and energetic warheads.Actually a nazi idea some 60 years old and intended for the same application improved armor through the use of armor with dissimilar propertys similar to casehardened armor but on a grand scale.Impenetrable panther tanks?

[Edited on 19-2-2009 by grndpndr]

[Edited on 19-2-2009 by grndpndr]

Im not understanding your constructionn method.look at AXTs linear SC on page 1 should give a good idea of proper construction.The idea of varying the standoff to help optimize standoff distances with one charge is clever.

still looking for the optimum diameter/radius of an EFP.Almost like state secrets although the cost of a proper steel or copper EFP would be prohibitive at least for me. But for the sake of knowledge it would be interesting, though not absolutely nescessary for an effective device unless size is an important consideration.
Has anyone else heard that the addittion of a thick steel mesh in front of a single dish efp will produce many smaller
efps to deal with multiple armored targets.Though factory made multiple efps have seperate lenses incorporated to accomplish the same more efficiently in arty delivered top attack submunitions
I dont know the reliability of this claim but ive heard of manhole covers being converted to efp like devices!

[Edited on 19-2-2009 by grndpndr]

[Edited on 19-2-2009 by grndpndr]

[Edited on 19-2-2009 by grndpndr]

As fascinating as saddle charges diamond charges etc are
The notion that laminated glass may be the key to defeating copper platter efps
is at least eaqually fascinating (to me anyway)The idea that layers of laminated glass may destabilize the EFP redirecting its KE along the glass laminations.Since Im in no way qualified to explain the phenomena ill direct you to the site \i discovered the info at.

Article title, "New Defense against explosively formed Penetrators" (EFPs)?
search the site "Defense Review"
Sorry I cannot provide a direct link.


The more I look at Octogens EFP the more I see a cone shaped charge? with a very shallow cone angle of 120 deg,
Is it a type of combination of the 2devices?The relatively shallow penetration with a large hole are ideal for a shaped charge intended for demolition work particularly that of quickly making a hole for a cratering charge effectually hampering access to bridges damaging rumways etc.

[Edited on 17-3-2009 by grndpndr]

[Edited on 17-3-2009 by grndpndr]

[Edited on 17-3-2009 by grndpndr]

Just look at another sample: MIACAH F1 mine is powerful and contains 6 kg of HEXOLITE. see how wide and thick liner is;this is certainly EFP rather than SC. source is http://ordatamines.maic.jmu.edu/.

[Edited on 19-3-2009 by octogen]

[Edited on 19-3-2009 by octogen]

[Edited on 19-3-2009 by octogen]

Thanks for the image and the link.What little I know of efps is that the platters(i thought) are always conical even multiple efps by thier description would seem to be conical or a geodesic like construction as thier desribed with individual 'lens' being formed into penetrators or sometimes imp multiple penetrators having a heavy steel meshover the platter producing the individual penetrators?I wish i could recall the source but Ill surely run across the same method(s)
if I search enough sources/patents

The liner yor referring to is obviously not made for any CSC Im aware of but that leaves alot of ground to cover as complex as some SCs have become .
Thanks ,
again,regards

Looks like some sort of adjustable aiming mechanism atached to the efp with a possible fold down site on top?

[Edited on 19-3-2009 by grndpndr]

Sounds plausible. Copper sheet could be cut in to triangles and soldered in to the shape of a baseless tetrahedron. I have never heard of this before but I am sure some penetration could be achieved.

Just trying to visualize in my head how such a liner would plasticly deform and collapse.

It would be much easier to keep the liner geometry within acceptable tolerances than trying to form a cone or hemi by hand using copper foil or sheet.

EDIT:

Would a baseless terahedral pyramid liner produce a hole resembling a three pointed star if standoff was not judged perfectly. Obviously the more sides the pyramid has the closer it is geometrically to a cone.

Would a twelve sided pyramid be that hard to construct and solder using 0.5mm Cu foil? ...maybe not

In theory a twelve sided pyramid is nearer to a cone than a three sided pyramid

But the three sided is structurally perfectly sound and is impossible to flex along the soldered hinges.

Our twelve sided option, or any other for that matter does not share this property. If I as to investigate this I would try it with the baseless tetrahedron.

One downside though with this design if a cylindrical case was used would be wastage of explosive so for this reason right off the bat, efficiency is compromised.

Quote: Originally posted by grndpndr

That very subject came up somewhere else iirc.Iwill look to see if I can find it again but my gut says if it were successful to any degree it would be patented/more info published on the subject. regards.

I believe the lost wax process of casting is within the capabilitys of the garage fabricator particularly the simple shapes of the hemisperical copper efp or the slighty angular
120 degree apex EFP platter could be roughly duplicated with a lost wax, sand cast mold at the garage or lathe equipped garage machine shop equipped with a crude coal or gas fired forge to melt the copper.I know crude forges made with castoffs will melt through the steel leaves used in
a leaf spring suspension I was forging knives from.Far more than enough heat than needed for copper simply a hole lined with brick and a reversed vacum connected to a steel pipe with spaced holes to allow escape of an air stream to feed 02 to the forge.Actually a large vacum is far to much! for a small forge a hand held vacum supplied excessive oxygen to my forge heating it to very extreme almost unusable temps which had to be shut down regularly or the steel melted with unnesscesary coal use.The sand castings are the most difficult but can be done likely with less effort than expected and with repeatable results using the same pieces to form the wax mold.
Possibly even usable as is with some hand finishing to remove flash etc.. Just exploring some Ideas for fabrication
of various munition components. Including the very obvious copper linear cones and more difficult but very doable copper cones using common sheet metal forming tools. In fact in lieu of the very expensive sheet metal brake a very inexpensive steel tool i believe added to the larger vise accomplished similar results at a cost of some $9.accuracy will suffer but far better than some improvised copper linear copper cones ive seen using angle Iron as the form and it appeared from the post allso part of the liner!? Copper sheet linear cone of sorts hammered over a piece of 1/4 in steel angle iron with the total used as the liner .no wonder results were nil.Also as copper flashing for the roofing trade becomes more common copper stock of varying gauges and widths are commonly available at better hardware /building centers.Good source for copper stock for these devices.

As is becoming painfully obvious w/o far better precision cones along with a HV castable or liquid ,slurry HE and precision assembly were just stuck in a rut and our results with CSCs,LSCs,and copper EFPs just cant improve despite a better explosive etc.It seems adequate simple HEs abound.
the problem is precision manufacture of copper cones and platters along with precision assembly.Next! tantalum efps
formed from punched 'pucks' of powdered tantalum heated and pressed.Maybe much for the garage,LOL but at this point it seems baby steps to produce even obsolescent CSCs/EFPs
tantalum.LOL
[Edited on 28-3-2009 by grndpndr]

[Edited on 28-3-2009 by grndpndr]