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. They were first developed during WWII ^[1]. Sectioned HEAT round with the inner shaped charge visible A shaped charge is an explosive charge shaped to focus the effect of the explosives energy. ... For other uses, see Armour (disambiguation). ... Stand-off, as regards warfare and weaponry, is the distance that one can safely attack an enemy while still being beyond the effective-range of their opponent. ... Technology during World War II played a crucial role in determining the outcome of the war. ...

Difference from conventional shaped charges

Formation of an EFP warhead. USAF Research Laboratory

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. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... “The U.S. Air Force” redirects here. ... Sectioned HEAT round with the inner shaped charge visible A shaped charge is an explosive charge shaped to focus the effect of the explosives energy. ... Hypervelocity is usually refered to a very high velocity, such as over 10,000 feet per second. ...

An 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^[2]. 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.^[3]. A detonator is used to trigger bombs, shaped charges and other forms of explosive device. ...

In addition to single-penetrator EFPs (also called single EFPs or SEFPs), there are EFP warheads whose liners are designed to produce more than one penetrator; these are known as multiple EFPs, or MEFPs. The liner of an MEFP generally comprises a number of dimples that intersect each other at sharp angles. Upon detonation the liner fragments along these intersections to form up to dozens of small, generally spheroidal projectiles, producing an effect similar to that of a shotgun. The pattern of impacts on target can be finely controlled based on the design of the liner and the manner in which the explosive charge is detonated.

The (single) EFP generally remains intact and is therefore able to penetrate armour at long range, delivering a wide spray of fragments of liner material and vehicle armour backspall into the vehicle's interior, injuring its crew and damaging other systems^[4]. Spall are flakes of a material that are broken off a larger solid body. ...

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.

EFPs have been adopted as warheads in a number of weapon systems, including the CBU-97 and BLU-108 air bombs (with the Skeet submunition), the M303 Special Operations Forces demolition kit, the M2/M4 Selectable Lightweight Attack Munition (SLAM), the SADARM submunition, the Low Cost Autonomous Attack System and the TOW-2B anti-tank missile. CBU-97 Developed and produced by Textron Defense Systems the CBU-97 is a United States Air Force 1,000 pound (450 kg) class non-guided (freefall) cluster bomb, hence the name CBU (Cluster Bomb Unit). ... THe BLU-108/B is an air bomb, containing four smart Skeets explosively formed penetrator (EFP) submunitions, manufactured by Textron Defense Systems. ... A submunition is the name given to a bomblet contained in a cluster bomb, generally 1% to 40% of this kind of bomblets explode, leting a large mine field. ... The M303 Special Operations Forces demolition kit is a type of land mine. ... Selectable Lightweight Attack Munition or (M2/M3/M4 SLAM) is a small United States multi-purpose landmine. ... The SADARM submunition, above, with the ram air parachute deployed, below with the ring vortex parachute deployed. ... Artist conception of LOCAAS. US Air Force Research Laborotary. ... A TOW missile being fired from a Jeep. ... An Anti-tank guided missile (ATGM) is a missile the primary purpose of which is to hit and destroy tanks. ...

Use in improvised explosive devices

Improvised Explosive Device in Iraq. The concave copper shape on top is an explosively formed penetrator.

EFPs have been used in improvised explosive devices against armoured cars, for example^[5] in the 1989 assassination of the German banker Alfred Herrhausen (attributed to the Red Army Faction)^{[citation needed]}, and by the Hezbollah in the 2006 Israel-Lebanon conflict^{[citation needed]}. A recent development is their widespread introduction in IEDs by insurgents in Iraq^[6]. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Munitions rigged for an IED discovered by Iraqi police in Baghdad, November 2005. ... A concave set (it has a dent). ... For other uses, see Copper (disambiguation). ... Munitions rigged for an IED discovered by Iraqi police in Baghdad, November 2005. ... A Rolls Royce armoured car 1920 pattern Railway shop workers built this vehicle for use by the Danish resistance movement near the end of World War II. For tracked, armored military vehicles, see Armored fighting vehicle. ... Banker Alfred Herrhausen fell victim to a terrorist bomb shortly after leaving his home in Bad Homburg on the November 30, 1989. ... Red Army Faction Insignia - a Red Star and a Heckler & Koch MP5 The Red Army Faction or RAF (German Rote Armee Fraktion) (in its early stages commonly known as Baader-Meinhof Group [or Gang]), was one of postwar West Germanys most active and prominent militant left-wing groups. ... For other uses, see Hezbollah (disambiguation). ... Combatants Hezbollah Amal LCP  Israel Commanders Hassan Nasrallah (Secretary General of Hezbollah) Imad Mughniyeh (Commander of Hezbollahs armed wing)[5] Dan Halutz (CoS) Moshe Kaplinsky[12] Udi Adam (Regional) Strength 600-1,000 active fighters 3,000-10,000 reservists[6] 30,000 ground troops (plus IAF & ISC)[13... Munitions rigged for an IED discovered by Iraqi police in Baghdad, November 2005. ... Iraqi militants celebrating orders that the surrounding Coalition forces were given to stand-down. ...

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 speed well over 1 km/s, depending on the design and type of explosive used. A concave set (it has a dent). ...

Because they use explosives to form a molten (technically, a super-plastically formed, but still solid) copper penetrator, instead of using an explosive blast or solid metal penetrator, these charges are extremely dangerous, even to the new generation of MRAPs (which are made to withstand an anti-tank mine), and many tanks^[7]. FPI Cougar HE in testing Mine Resistant Ambush Protected (MRAP) vehicles are a family of armored fighting vehicles designed to survive IED attacks and ambushes. ... An Anti-tank mine, or AT mine is similar to a Landmine except generally designed with a less sensitive trigger and more explosive power so as to be able to take out an armored vehicle, and not go off until such a vehicle comes along. ...

Often mounted on crash barriers at window level, they are placed along roadsides at choke points where vehicles must slow down, such as intersections and junctions. This gives the operator time to judge the moment to fire, when the vehicle is moving more slowly^[8].

Detonation is controlled by cable, radio control (RC), or remote arming with passive IR (PIR) trigger. EFPs can be deployed singly, in pairs, or in arrays, depending on the tactical situation. 6 or 15cm outside diameter, oil-cooled cables, traversing the Grand Coulee Dam throughout. ... This radio control airplane is carrying a scale model of X-33 and is taking part in NASA research. ... An infra-red search and track (IRST) system (sometimes known as infra-red sighting and tracking) is a method for detecting and tracking objects which give off infrared radiation such as jet aircraft and helicopters. ... An ambush is a long established military tactic in which an ambushing force uses concealment to attack an enemy that passes its position. ...

References

• Fundamentals of Shaped Charges, W.P. Walters, J.A. Zukas, John Wiley & Sons Inc., June 1989, ISBN 0-471-62172-2
• Tactical Missile Warheads, Joseph Carleone (ed.), Progress in Astronautics and Aeronautics Series (V-155), Published by AIAA, 1993, ISBN 1-56347-067-5

See also

• High explosive anti-tank
• Misznay-Schardin effect
• Munroe effect

A HEAT round. ... The Misznay-Schardin effect is a characteristic of the detonation of a broad sheet of explosive. ... The Munroe effect refers to the partial focusing of blast energy caused by a hollow or void cut into a piece of explosive, a property which is exploited by a shaped charge. ...

External links

• Photo of a Canadian "Mach 6 aerodynamic EFP"
• Video of EFP trying to take out a Humvee