Syria: Plenty of Nuthin'

[John Kettler]

Peter Cairns and Troops,

Just found this most interesting discourse on HEAT

liner technology. It turns out that DU liners are eminently doable and quite effective, just harder and more expensive to manufacture. The same properties, though, that make the 120mm DU Silver Bullet so deadly apply even more here, for the velocities involved are much greater.

http://yarchive.net/mil/shaped_charges.html

Regards,

John Kettler

[Peter Cairns]

If the ideal liner is a combination of density and ease of manufacture, I'd have thought lead would be pretty much the material of choice.

it's cheap, dense, easily moulded, and available world wide.

Peter.

[John Kettler]

Peter Cairns,

The first shaped charge ever recorded had no liner at all, but instead had the manufacturer's name pressed into the explosive face. Noticing that this was burned into the witness plate on detonation led to the discovery of the Munroe effect. Copper was commonly used once things got going, and I have heard of steel as well. Back in the 80s there was a guy (forget his name) who wrote an article in ARMOR on the development and history of the shaped charge which was simply stunning in both depth and breadth. The footnotes, which were in tiny type, went on for pages. He subsequently went to work for the CIA as the in house expert on shaped charge technology worldwide. It was he who briefed us at Soviet Threat Technology conferences on some of the scary discoveries about what

obsolete Soviet export model HEAT warheads could do to shiny M1s, including the unpleasant discovery that by static firing the gun launched stuff in tests we were understating actual penetration by multiple tens of percentage points.

FWIW, I've never heard or read anything about using lead for a HEAT liner.

Regards,

John Kettler

[MikeyD]

"It turns out that DU liners are eminently doable and quite effective, just harder and more expensive to manufacture."

The nasty new self-forging projectile off-route mines currently seen in Iraq are said to use steel or copper 'plates'. The U.S. 'skeet' self-forging projectile that may have been the initial design source uses a DU 'lense' that is collapsed by the explosion into a projectile slug. Its velocity is higher than a 120mm tank round, and is said to be capable of igniting diesel fuel.

Only problem with DU in a weapon is afterwards cleanup's a b*tch. Its a great idea for fighting foreign wars but not so good when its YOUR backyard that gets contaminated with aerosized uranium particles.

[Peter Cairns]

Mikey,

Given how the "Skeet" works, its odd that no one has come up with a AT weapon that predetonates and hits with a high velocity "Slug", rather than a shaped charge.

If they did I doubt the Strykers armour or "cage", would do much to stop something moving at that speed.

Peter

[akd]

Originally posted by Peter Cairns:

Mikey,

Given how the "Skeet" works, its odd that no one has come up with a AT weapon that predetonates and hits with a high velocity "Slug", rather than a shaped charge.

I'm fairly certain this is how top-attack "explosively-formed projectile" warheads work.

edit: yeah, see here:

Explosively Formed Projectile (EFP)

Wide angle cones and other liner shapes such as plates or dishes do not jet, but give instead an explosively formed projectile or EFP. The projectile forms by dynamic plastic flow and has a velocity of 1-3 kms-l . Target penetration is much less than that of a jet, but the hole diameter is larger with more armour backspall.

The concept of using explosive energy to deform a metal plate into a coherent penetrator while simultaneously accelerating it to extremely high velocities offers a unique method of employing a kinetic energy penetrator without the use of a large gun. A typical explosively formed projectile (EFP) is comprised of a metallic liner, a case, an explosive section, and an initiation train. Very often there is also a retaining ring to position and hold the liner-explosive subassembly in place. EFP warheads are normally designed to produce a single massive, high velocity penetrator. After detonation, the explosive products create enormous pressures that accelerate the liner while simultaneously reshaping it into a rod or some other desired shape. The EFP then hits the target at a high speed, delivering a significantly high mechanical power.

An EFP warhead configuration may be comprised of a steel case, a high-explosive charge, and a metallic liner. Explosively formed penetrator (EFP) warheads have been designed to project a single massive high velocity penetrator to attack the top of armored vehicles. Such armor perforation capability needs further improvement to counter new generations of harder armored vehicles, without resorting to a larger caliber weapon system. In developing a warhead configuration that meets system constraints and also meets performance requirements, several parameters in the warhead configuration must be redesigned to achieve an optimum configuration. Several warhead configurations have been developed to accommodate varying system constraints.

...

Two major applications have evolved for explosively formed projectiles or warheads, namely, long-standoff sensor-fuzed submunitions and medium standoff, close-overflight missiles. The former application, which is the more traditional one, requires the formation of a single-piece EFP capable of flying in a stable fashion to the target. This refinement has led to the flared EFP rod and, more recently, to the finned EFP rod designs.

For the medium or short-standoff applications, a new type of EFP was developed. The need for an aerodynamic shape is not necessary for these applications because of the short distance the EFP must travel, hence, the length of the rod was increased and the flared tail was eliminated from the design. In fact, some of these rods are purposely stretched beyond their breaking point and fracture into several pieces resulting in greater total length.

Prior art devices have tried to solve this problem of selectable effects through the use of different or multiple initiation points for the shape charge munition. The complex shape of the detonation wave produced was intended to interact with the liner causing it to break up into a number of individual fragments. The problem with this approach is that it requires a relatively complex initiation scheme.

http://www.globalsecurity.org/military/systems/munitions/bullets2-shaped-charge.htm

e.g. TOW 2B

[ January 23, 2006, 11:30 AM: Message edited by: akd ]

[MikeyD]

I recall in the Pentagon handout on that Iraq SFP mine photos showed several big holes knocked in the side of an M1117. It looked like the metal plate that was supposed to form into a single projectile was fragmenting into several big chunks. This would significantly lower the penetration ability of the weapon. Good news for the M1 Abrams, though it's still more than lethal enough to give light armor troubles.

SFP warhead in TOW 2B? Blame the old Soviet habit of putting reactive armor blocks on their tanks roofs.

[Peter Cairns]

I was interested in this as it seemed the obvious wway to overcome, the proposed suystem of "electric" armour, which uses a high voltage to disperse and disrupt the plasma of a conventional shaped charge.

Peter.

[MikeyD]

There was a rumor going around for awhile that Stryker armor was electrified. Turn out all it was was steel bars spaced 3" between slats. that's all that was needed to stop the 3.3 inch diameter RPG warhead! Nothing fancier than that, from what i hear.

[flamingknives]

Shaped charges don't produce plasma. It's a hyper velocity jet of fluid, solid-phase, metal.

[Peter Cairns]

A hyper velocity jet of super heated fluid, is a plasma, that's why it can be dispersed by an electric field, in that state mid way between a gas and a solid,

Wikipedia says

Plasma (physics)

From Wikipedia, the free encyclopedia.

A Plasma lamp, illustrating some of the more complex phenomena of a plasma, including filamentation

In physics and chemistry, a plasma is an ionized gas, and is usually considered to be a distinct phase of matter. "Ionized" in this case means that at least one electron has been dissociated from a significant fraction of the molecules.

The free electric charges make the plasma electrically conductive so that it couples strongly to electromagnetic fields.

This fourth state of matter was first identified by Sir William Crookes in 1879 and dubbed "plasma" by Irving Langmuir in 1928, because it reminded him of a blood plasma [3].

I also found this,

IED – Shaped Charges

A new type of IED consists of "shaped charge", located under the road surface or at the side of the road.

In these explosive devices, a cone (also known as concave) made of copper is covering an explosive charge creating a hollow space in front of and along the axis of the charge.

When the explosive is activated, the copper transforms into a forceful jetstream of molten metal also known as "plasma".

This plasma jet easily perforates an unprotected steel armor, hitting the surface at a speed of 8,000 meters per second and extremely high pressure. If the plasma is not obstructed by a target within few meters, it solidifies into a kinetic slug which is less effective against heavy armor but is still devastating against softer targets.

In both cases, the effect inside the target interior can be catastrophic, especially if it ignites unprotected ammunition stores, causing secondary explosions. Anti-tank shaped charges must be employed with utmost accuracy (activation distance, and design accuracy). Therefore, they are used primarily with buried mines, and lightweight anti-tank weapons.

I think this is a misunderstanding more than an arguement, as shape charge warheads do create a plasma that is sensetive to high voltage electricity, however as we see here if the range is to great we get the "Slug" effect.

Peter

[flamingknives]

Peter, in all honesty when I have, on one hand, wikipedia and on the other several textbooks, a university professor and a department of warhead designers, I think I'll go with the fluid solid-phase description. Hydrostatic yeild is the key feature.

Apart from anything else, I'm pretty sure that you can't take x-rays of plasma.

Of course, once said jet has passed through 2 feet of armour it's going to have generated a fair bit of heat.

[Peter Cairns]

Flamingknives,

I think I've found the problem , or rather my mistake. It seems the account talks about the charge converting the copper jet, "in to a Plasma" as opposed to it being a plasma,

The second reference is apaper that I thought you might find intersting as this seems to be your area of expertise, I am afraid I got a bit lost after about page 2.

Peter.

Electric reactive armour

A new technology of Electric Reactive Armour is in development, where the armour is made up of two or more conductive plates separated by an insulator, creating a high-power capacitor.

In operation, a high-voltage power source charges the armour. When an incoming body penetrates the plates and closes the circuit, the capacitor discharges, dumping a great deal of energy into the penetrator, which may vaporize it or even turn it into a plasma, significantly diffusing the attack.

It is not public knowledge whether this is supposed to function against both KE-penetrators and shaped charge jets, or only the latter. This technology has not been introduced on any operational platform.

(Type this in and you should find the paper)

[PDF] Use of images to model off-axis forces in an electric armour array ...

File Format: PDF/Adobe Acrobat -

View as HTML

2 The electric armour array showing the 12 faces of the plates ... distribution and resistance characteristics in plasma injectors for electro- ...

eprints.ecs.soton.ac.uk/9405/ 01/IEE-Proc-vol151no3May2004page151.pdf

[flamingknives]

Thanks Peter - I don't think I'll have much more luck though - electric fields are not my strong point.

[Peter Cairns]

flamingknives.

I have been looking at what I can find on two subjects, basically I searched for

"Copper, Shaped Charge, Pressure, temprerature",

and

"Copper, Pressure, Temperature, Plasma".

I can't make much head or tail of some of it as it seems to be most solid atate physics papers etc, But I think we might both be right.

The Shaped charge does produce a jet at between 7,000m's ( front) and 1,500ms (rear) at a very high pressure, followed by about 80% of the liner, which if the distance to the target id too far, may become a slug.

However from the stuff on plasmas, it seems that at that kind of temperature and pressure copper can become a plasma.

Now we know tha copper starts as a solid, and that it doesn't vaporise in to a gas, but at those temps and pressures, is it a liquid or is it a plasma.

Plasmas are sometimes refered to as a mid state between solid and gas, so the question is if you had to make a choice between four options, which would you say that it was, between detonation and contact....Solid, Liquid, Gas, or Plasma.

Most people when asked would say that water was a liquid, but of course it's not, its a molecule (H2O), It can be aliquid, but also a solid or gas...

So It could just be that we're both right, though it's hardly the particle wave dicotomy.

Peter.

[flamingknives]

Peter:

Beware the difference between fluid and liquid. Apply enough pressure to a material and it will flow like a liquid, but it is still technically a solid.

Paragraph 5 in 'Shaped Charge Theory' in the following link has it reasonably well covered.

http://www.globalsecurity.org/military/systems/munitions/bullets2-shaped-charge.htm

I'm not sure why there is a perception that it must be molten though.

I object to the use of 'plasma' to describe the jet as this implies that temperature is part of the armour defeat mechanism.

It isn't - heat transfer cannot work that fast. It's pure kinetic energy.

[John Kettler]

If it helps any, what we now call EFPs are technically known as Miznay-Schardin devices or "P" (as in plate) charges. For many years now, the U.S. has had an AT mine in service of this type, and back in the 1980s the Red Brigades in Germany used a homemade P charge device to kill a senior Deutsche Bank official and several bodyguards by smashing right through the side a heavily armored Mercedes Benz sedan supposed to protect him. The Gator scatterable antiarmor mine is another such device, as is the Skeet. TOW2/B,

as shown in the diagram, uses two P charges, and the Bill system, I believe, also has a P charge warhead. The Kormoran antiship missile warhead is a kind of omnidirectional P charge, flinging dozens of separate projectiles energetic enough to rip right through a ship's internals.

Regards,

John Kettler

[Peter Cairns]

flamingknives,

For me, and in the context of electric armour, it's not the heat thats a factor, I've never thought that they burned, there way through, but the fact that in that state between soild and gas, the structure and even direction of the jet can be altered by a magnetic field.

It is that which makes me think that as it reacts to a charge laike a plasma then it probably is one.

Peter.