Explosively formed projectiles

[Werner]

These weapons, invented primitively in 1942, have the ability to penetrate any armor up to and beyond 1,000 calibers in thickness.

The EFP is relatively unaffected by first-generation reactive armour and 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.

This means that an evolved 5" shell should be able to penetrate up to 416 feet of standard armor.

There is a story that the USA developed a nuclear EFP weapon after Gulf.I. I wonder if it was meant to assault the devil himself in the seventh ring of Hell.

If this technology had been pursued in the 1940s, it would have made all armor obsolete and brought about Jackie Fisher's maxim of fire fast and go fast.

Meanwhile, we need to develop systems to defeat these projectiles before they find their target for no ship, airplane or tank is immune.

I wonder if I can modify the Des Moines vs Yamato battle to include EFPs for the US Cruiser's 8-inch gun.

[Gone Asiatic]

How about a match between Des Moines and Space Battleship Yamato with "Laser" cannons!

[Foeth]

If this were true, why are we firing DU or Tungesten from our tank guns?

[richter111]

Ok I'm going to step out and hang my ignorance out for all to see.

With this technology, assuming it could be developed to it's full potential, would be incredible.

You could have anti-tank rounds fired from rifles, just have a spare magazine next to you M-16

The A-10 tank buster could carry a small calibre gun pod, and be equally effective.

There had to be something that prevented this technology from assuming it's natural course.

So what am I missing. (I assume a LOT)

Ric

[Roger T]

I get the impression, from an admittedly cursory glance on t'internet, that these EFP rounds are fairly wide in diameter things. They are, therefore, probably not capable of being shrunk to the size of a rifle bullet.

These weapons, invented primitively in 1942, have the ability to penetrate any armor up to and beyond 1,000 calibers in thickness.

The EFP is relatively unaffected by first-generation reactive armour and 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.

This means that an evolved 5" shell should be able to penetrate up to 416 feet of standard armor.

I suspect, Werner, that you have misread your source quote; I don't think it says that these EFPs can penetrate 1,000 times their diameter in armour thickness, but that the jet of molten metal created by the explosion of the EFP can travel through air for a distance of up to 1,000 times the round's diameter before atmospheric drag slows it so much as to lose its penetrative effectiveness, or it merely misses the target. You have, I suspect, confused effective standoff distance with penetrative capability. Therefore, to use your example of a 5" EFP round, the shell could explode up to 416 feet away from the armoured target and still stand a chance of penetrating it.

On Military.com, we find this table (http://www.military.com/soldiertech/0,1 ... P,,00.html):

XM303 Kit [a type of standoff demolition charge]
EFP Type...........Standoff...........Target
Small................1ft.-50m...........>1 in.RHA*
Medium.............2ft.-50m...........>2 in. RHA*
Large................10ft.-50ft..........8"-24" Concrete

*Rolled Homogeneous Armour: a sort of baseline standard for armour

[Guest]

If this were true, why are we firing DU or Tungesten from our tank guns?

I noticed US defense department sometimes toss statements to military fans that sounds fantastically exciting on the surface, but are phrased so broadly that they contains no specific information whatsoever and is therefore impossible to falsify. The statement that an ammunition can penetrate armor up to 1000 times its own diameter remains true whether the maximum penetration capability of the ammunition is in fact zero, or 999.99 times its own diameter, or anywhere in between. The uncritically adoring fans of US military might would then immediately latch onto the most extravagant possible interpretation of these statements, while ignoring an infinite number of others that place far less demand upon credulity.

[Guest]

I wonder if I can modify the Des Moines vs Yamato battle to include EFPs for the US Cruiser's 8-inch gun.

I move to give Yamato 18" nuclear shells, which strains credulity less than 5" shells that can penetrate 416 feet of armor.

I know from NASA experiments conducted for purpose of Project Orion that a nuclear weapon of the yield to be expected from the US 16" nuclear shell shipped in the Iowa class battleship in fact can not penetrate 416 extrapolated feet of homogeneous steel armor.

[Werner]

I get the feeling the is the state of the art and not fully deployed yet, although the Iraqi insurgency is credited with killing an M1 Abrams with an Iranian weapon of this "rod" type.

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.

Explosively Formed Penetrator warheads can defeat the target at very long standoffs. EFP warheads consist of an explosive billet and a metal liner. When the explosive is detonated, the detonation wave forms the liner into a high-speed long rod penetrator and propels the penetrator towards the target at speeds greater that Mach 6.

An EFP must be aerodynamically stable so as to strike the target within a small miss distance and a small angle of obliquity. In the U.S., extensive work has focused on forming EFPs with canted fins, to induce spin-up. By forming canted fins on an EFP, improvements in aerodynamic stability can be realized.

Current anti-armor ordnance employ explosively formed elongated penetrators for piercing armored vehicles and equipment. Such penetrators are generally one of two types: rearward folding or forward folding. In forward folding types a warhead containing an explosive charge drives the periphery of a metal plate, referred to as a liner, forward with an axial velocity greater than the axial velocity of the central portion causing the periphery to fold over and converge forward of the central portion and form an elongated penetrator. In rearward folding the explosive charge drives the periphery of the liner forward with an axial velocity less than the axial velocity of the central portion causing the periphery to fold over and converge rearward of the central portion to form the elongated penetrator.

In these approaches, then, the axial velocity component is critical in determining the final desired shape of the penetrator and this is a well accepted technique. However, in certain applications, for example, where the explosively formed penetrator is delivered from the warhead assembly of a missile or projectile, the explosively formed penetrator encounters the skin of the missile or projectile during the critical earlier stages when the liner is being formed into the penetrator shape by the folding action of the periphery over the center. The engagement of the liner with the skin radically alters the axial velocities of the periphery thereby disrupting the folding. This disruption of the forming/ process causes the penetrator to fragment or otherwise lose its effectiveness as a penetrator. To avoid this, provision is made to remove the impeding portion of the skin using clearing charges or skin just prior to the liner folding action cutting devices which significantly increase the cost and complexity of the systems.

In consequence of the development that has taken place on the protection side through the introduction of composite armor, active armor, etc., the importance of improving the penetrability of the warhead has, however, increased. Developments have therefore led to increasingly longer and heavier hollow charges. In certain cases this can be accepted, typically for all-target shells etc., but for severely weight-optimized designs, with limited space etc., this method is inappropriate. With state-of-the-art technique, therefore, limit has been reached in practice as regards the length and weight of the charges.

In order to increase the penetrability, hollow charges differing from conventional hollow charges have also been developed in recent times. These charges can, for instance, comprise an auxiliary body disposed in front of or integrated with the metal cone of the charge so that upon initiation of the charge it generates a slug which follows behind the actual penetration jet and penetrates and enlarges the hole made by the penetration jet. Alternatively, the hollow charge may have a warhead with two complete hollow charges, so-called tandem hollow charges, which after the projectile is fired accompany each other as an integral unit during the greater part of the travel towards the target, only to separate at a predetermined distance from this and to continue towards the target at mutually slightly different velocities along largely the same trajectory and thereafter to hit the target with a sufficient interval of time to enable the charge which reaches the target first to detonate the explosive in any active armour before the second charge reaches the target, so that this latter charge penetration jet is able to work without disturbance and also is assisted by the penetration work already performed by the first charge which has already detonated within the same confined area of the charge.

In order to function in the intended manner each of the two hollow charges in such a tandem hollow charge must have its own ignition system with associated safety device. To separate the two hollow charges, it is also necessary to have a smaller parting charge, e.g. a powder charge, between the two charges in order to impart to each of these its own velocity change.

It is realized that the penetrating ability against active armor can be increased significantly through two such interacting charges. It is also realized, however, that the warhead of the projectile will be significantly more expensive with two complete hollow charges, each including its own ignition system and a parting charge.

A tandem-projectile can be adapted in particular for compartmentalized targets (multi-layer armor). Two armor-penetrating devices are incorporated in the shell body of a tandem shell. These armor-penetrating devices distinguish each other with respect to their moment of impact; the rear one of the two devices encompasses a shaped hollow explosive charge arrangement. Such a device has two coaxial shaped hollow explosive charges arranged one behind the other. When the device impacts on a target the rear shaped hollow explosive charge is the one that first becomes operative. From a lining forming part of the rear charge a pointed spike is formed; this spike is adapted to be ejected through the forward hollow charge by passing through an opening disposed in the apex of the forward charge and produces a channel in the armor plate of the target. The forward shaped hollow explosive charge is thus ignited with delay relative to ignition of the rear shaped hollow explosive charge. The pointed spike formed by the forward shaped hollow explosive charge thus follows the said channel produced by the rear shaped hollow explosive charge and becomes operative at a preselected position.

It has been observed that difficulties occur when the compartmentalized reinforced target is impacted obliquely by the afore-described known projectile. The difficulties can be attributed to the strongly reduced cross section of the penetrating channel produced by the spike of the first shaped hollow explosive charge as compared to the cross section of such a channel when a perpendicular impacting of the shell and the target occurs. Consequently, only a relatively small surface area is damaged which is a drawback. A further drawback resides in the behavior of such a known shell relative to an active armor. What is meant here by an active armor is an arrangement of explosive charges in the region of the outer armor, by the activation of which the spike formed by the shaped hollow explosive charge is disturbed and is made ineffective with respect to the main armor.

Advanced armor techniques employ a small armor explosive charge that can deform the explosive cone of a shaped charge or deflect the armor piercing subcaliber round normally used in destroying armor such as on a tank. Therefore, there is a need for a multi-warhead that has the capability of defeating armor that is protected with an outer explosive charge arrangement that is designed to defeat a round that has a single blow effect. Therefore, it is an object of this invention to provide a multi-warhead that has a multiplicity of subcaliber warheads that are designed to strike the target and destroy the small protective explosive charges around the armor and then deliver the main warhead to the armor proper for piercing the armor in an effective manner.

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.

[Chuck~]

I get the feeling the is the state of the art and not fully deployed yet, although the Iraqi insurgency is credited with killing an M1 Abrams with an Iranian weapon of this "rod" type.
.......

There have been too much BS going around about how tough modern MBTs are. The major post WWII protection improvement on MBTs came over the front and side of the turret and the front of the hull. A few of the Latest MBTs like Swedish version of Leopard II and the LeClerk also feature enhanced top protection, but M-1 doesn't have it. The back, top, bottom, and hull sides of modern MBT like the M-1 would not be much better protected against either chemical and kenetic energy weapons than the better WWII designs. M-1 also contain design flaws that admits many more shot traps than the likes of Leopard II, Leclerk and Type 90. I bet a teller mine wedged between M-1's hull and turret would blow off its turret just as effectively as it did the turrets of T-34s. If modern MBT is sent into confined urban and semi-urban combat against enemy equipped with WWII era anti-tank weapons like the Panzerfaust and Bazooka, I would expect serious casualties. So it should be no surprise that M-1 and Merkavas are taking casualties from weapons that are better than WWII weapons. There is absolutely no need to attribute state of the art weapon capability to the Iraqi insurgents to explain casualties amongst even state of the art tanks.

[Werner]

I don't pretend to be a land warrior, but a couple pound tungsten flechette spin stabilized and striking my hull at Mach 6 has to be significant.

[chuck]

I don't pretend to be a land warrior, but a couple pound tungsten flechette spin stabilized and striking my hull at Mach 6 has to be significant.

Yes, but modern tanks can be knocked out by much less.

[Werner]

So what if I put a larger tungsten slug in a 5-inch or 8-inch shell and now there are 20 or 100 pounds of tungsten hitting your belt or deck at Mach 6?

The entire plate which was struck would be seriously weakened or destroyed by backspall and direct penetration, and the system of restraints which hold the armor in place might also be jeopardized.

If after five minutes of these EFP shells I switch to conventional warheads, I'd say the target is in serious trouble.

Even better, if the EFP could function as a cap to a conventional shell, the entrained HE or AP shell would strike exactly where the EFP nosecone prepared the way for it.

[Roger T]

I noticed US defense department sometimes toss statements to military fans that sounds fantastically exciting on the surface, but are phrased so broadly that they contains no specific information whatsoever and is therefore impossible to falsify. The statement that an ammunition can penetrate armor up to 1000 times its own diameter remains true whether the maximum penetration capability of the ammunition is in fact zero, or 999.99 times its own diameter, or anywhere in between.

I ask again: if we go only by Werner's quote, where is the statement that these EFPs can penetrate armour thicknesses up to 1,000 times the charge diameter? All I see is a quote that states that the EFP can travel through the air for a distance of up to 1,000 times the charge diameter before losing its effectiveness when it then hits the target armour.

Nobody has bothered to answer this point, but I would be interested to see a definitive answer because, quite frankly, I remain utterly sceptical of the fantastical claim that EFPs can penetrate armour thicknesses up to 1,000 times the charge diameter.

[Foeth]

Note that the 120mm gun used in the Abrams and Leopard 2 can penetrate over 3 feet of armoured steel. The latest US ammo with DU penetrates over a meter. Now, I don't know what type of steel and so forth, but any decent tank can penetrate a WWII battleships armour without any trouble.

[JWintjes]

There have been too much BS going around about how tough modern MBTs are. The major post WWII protection improvement on MBTs came over the front and side of the turret and the front of the hull. A few of the Latest MBTs like Swedish version of Leopard II and the LeClerk also feature enhanced top protection, but M-1 doesn't have it. The back, top, bottom, and hull sides of modern MBT like the M-1 would not be much better protected against either chemical and kenetic energy weapons than the better WWII designs.

While I agree that modern MBTs tend to be overrated when it comes to protection, this is going too far - it really depends on the way the tank is designed; the Merkava offers a lot more passive protection due to its general design than a M-1/Leo II type tank.

M-1 also contain design flaws that admits many more shot traps than the likes of Leopard II, Leclerk and Type 90.

Not that shot traps matter that much when your enemy is hurling 125mm Sabot rounds at you...

I bet a teller mine wedged between M-1's hull and turret would blow off its turret just as effectively as it did the turrets of T-34s. If modern MBT is sent into confined urban and semi-urban combat against enemy equipped with WWII era anti-tank weapons like the Panzerfaust and Bazooka, I would expect serious casualties.

Careful.

If you send modern MBTs into a confined urban area, you are bound to take losses, no matter how sophisticated the tank is. This has nothing to do with tank design, but with tactical use.

There is absolutely no need to attribute state of the art weapon capability to the Iraqi insurgents to explain casualties amongst even state of the art tanks.

While that is correct in theory there is ample evidence for state-of-the-art weaponry among Iraqi insurgents.

Jorit

[Guest]

While I agree that modern MBTs tend to be overrated when it comes to protection, this is going too far - it really depends on the way the tank is designed; the Merkava offers a lot more passive protection due to its general design than a M-1/Leo II type tank.

Compare what any projectile approaching the tank from the top, bottom, rear, or hull side under the sponson will encounter before entering the tank's interior spaces, and you would find Tiger II had better direct protection in those areas than any of the modern tanks. The moderns tanks had better internal indirect protection in the form of spall shields, automatic fire suppression, and blow off panels, but in terms of direct penetration resistance, the improvements of last 60 years does not extend to these areas.

The main survival improvement of modern tanks is in mobility, ability to fire on the move, smaller target profile, and much improved direct protection over the frontal arc. In other words survival prospect in a hypothetical massed tank battle in central Europe developed somewhat along the lines of WWII era tank battles on the eastern front has been enhanced at the expense of enhancements in other possible application of tanks. In close urban battles, I'd rather be in a Tiger II.

[JWintjes]

Compare what any projectile approaching the tank from the top, bottom, rear, or hull side under the sponson will encounter before entering the tank's interior spaces, and you would find Tiger II had better direct protection in those areas than any of the modern tanks. The moderns tanks had better internal indirect protection in the form of spall shields, automatic fire suppression, and blow off panels, but in terms of direct penetration resistance, the improvements of last 60 years does not extend to these areas.

Chuck,

don't believe the Germanotech Mafia that's dominating the hobby - the Tiger II wasn't the super weapon of the war.

Besides, 80mm at around 20 degs if I remember correctly isn't much of a side armour, particularly not if it's simple steel. You could knock it out with any larger RR gun. In case of the Merkava, you'll get a mobility kill if anything.

In close urban battles, I'd rather be in a Tiger II.

I'd prefer not to sit in something that's gravely undermotorized, particularly in close urban battles...

Jorit

[Guest]

Chuck,

don't believe the Germanotech Mafia that's dominating the hobby - the Tiger II wasn't the super weapon of the war.

No one said it was. But it had reasonably thick skin on the side and the back. For my purposes what is reasonably thick skin on the back and side is already thicker than what is found on the back of Leopard II, M-1 and LeClerk, and that was enough to demonstrate the point.

[Guest]

I'd prefer not to sit in something that's gravely undermotorized, particularly in close urban battles...

Jorit

Something Like Merkava I and II?

Actually, in between failures of final drive, Tiger II's degree of motorization is not ill suited to urban combat.

[JWintjes]

Chuck,

don't believe the Germanotech Mafia that's dominating the hobby - the Tiger II wasn't the super weapon of the war.

No one said it was. But it had reasonably thick skin on the side and the back. For my purposes what is reasonably thick skin on the back and side is already thicker than what is found on the back of Leopard II, M-1 and LeClerk, and that was enough to demonstrate the point.

Ehm, 80mm cold WW2 steel? Leopard II has 60mm composite, LeClerc similar, Challenger II is generally assumed to have considerably more.

Let's stay with the facts - the Tiger II is markedly inferior when it comes to protection. Anything else is nonsense.

Jorit