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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 standoff distances. As the name suggests, the effect of the explosive charge is to deform a metal plate into a slug or rod shape and accelerate it toward a target. They were first developed during WWII.〔(Military.com article on the evolution of hand-held anti-tank technology )〕 ==Difference from conventional shaped charges== A conventional shaped charge generally has a conical metal liner that projects a hypervelocity jet of metal able to penetrate steel armour to great depths; 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. An EFP, on the other hand, has a liner face in the shape of a shallow dish. The force of the blast molds the liner into any of a number of shapes, depending on the shape of the plate and how the explosive is detonated.〔(U.S. Air Force Research Laboratory description of an EFP )〕 Some 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 fragments into multiple penetrators.〔(U.S. Patent 5540156: Selectable effects EFP warhead )〕 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. A nuclear-driven MEFP was apparently proposed by a member of the JASON group in 1966 for terminal ballistic missile defense.〔Explosively Produced Flechettes; JASON report 66-121, Institute for Defense Analysis, 1966〕〔Interview with Dr. Richard Blankenbecler http://www.aip.org/history/ohilist/5196.html〕 A related device was the proposed nuclear pulse propulsion unit for Project Orion. The (single) EFP generally remains intact and is therefore able to penetrate armour at a 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.〔(DoD Directive 2000.19E, "Joint Improvised Explosive Device Defeat Organization (JIEDDO)", February 14, 2006 )〕 As a rule of thumb, an EFP can perforate a thickness of armour steel equal to half the diameter of its charge for a copper or iron liner,〔ng.pdf, on the web, US military testing of SOFDK〕 and armour steel equal to the diameter of its charge for a tantalum liner, whereas a typical shaped charge will go through six or more diameters. The penetration is proportional to the density of the liner metal; tantalum 16.654 g/cm3, copper 8.960 g/cm3, iron 7.874 g/cm3. Tantalum is preferable in delivery systems that have limitations in size, like the SADARM, which is delivered by a howitzer. For other weapon systems where the size does not matter, a copper liner of double the calibre is used. Extensive research is going on in the zone between jetting charges and EFPs, which combines the advantages of both types, resulting in very long stretched-rod EFPs for short-to-medium distances (because of the lack of aerostability) with improved penetration capability. 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. An EFP eight inches in diameter threw a seven-pound copper slug at Mach 6, or 2,000 meters per second. (A .50-caliber bullet, among the most devastating projectiles on the battlefield, weighs less than two ounces and has a muzzle velocity of 900 meters per second.)—Rick Atkinson, ''The Washington Post'' 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「explosively formed penetrator」の詳細全文を読む スポンサード リンク
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