Anti-handling device
Encyclopedia
Fuze
Fuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...
types found in air-dropped bombs such as the M83
Butterfly Bomb
A Butterfly Bomb, or was a German 2 kilogram anti-personnel submunition used by the Luftwaffe during the Second World War. It was so named because the thin cylindrical metal outer shell which hinged open when the bomblet deployed gave it the superficial appearance of a large butterfly...
, cluster bombs and sea mines. It is specifically designed to prevent tampering. When the protected device is disturbed it detonates, killing or injuring anyone within the blast area. There is a strong functional overlap of booby trap
Booby trap
A booby trap is a device designed to harm or surprise a person, unknowingly triggered by the presence or actions of the victim. As the word trap implies, they often have some form of bait designed to lure the victim towards it. However, in other cases the device is placed on busy roads or is...
s and anti-handling devices: a munition with an anti-handling device fitted has, for all intents and purposes, been booby-trapped.
Purpose
Anti-handling devices serve two military purposes:- To prevent the capture and reuse of the munition by enemy forces.
- To hinder bomb disposal or deminingDeminingDemining or mine clearance is the process of removing either land mines, or naval mines, from an area, while minesweeping describes the act of detecting of mines. There are two distinct types of mine detection and removal: military and humanitarian.Minesweepers use many tools in order to accomplish...
operations, both directly and by deterrenceDeterrence (psychological)Deterrence is a theory from behavioral psychology about preventing or controlling actions or behavior through fear of punishment or retribution...
, thereby creating a much more effective hazard or barrier.
Anti-handling devices greatly increase the impact of munitions on civilian populations in the areas in which they are used because their mechanisms are so easily triggered. An unexploded bomb may or may not detonate if it is lifted or overturned, whereas an anti-tank mine with an anti-handling device fitted is almost guaranteed to detonate if it is lifted/overturned, because it is specifically designed to do so. Additionally, munitions fitted with anti-handling devices increase the difficulty and cost of post-conflict clearing operations, due to the inherent dangers of attempting to render them safe.
Not all munitions will have an anti-handling device fitted or enabled. Perhaps one in ten antitank mines in a large defensive minefield will have boobytrap firing devices screwed into their secondary fuze wells. Even so, deminers and EOD personnel are forced to assume that all items they encounter may have been boobytrapped, and must therefore take extra precautions. This has the effect of significantly slowing down the clearance process, even allowing for the fact that the anti-tank mines in question may be interspersed with various different types of minimum metal
Minimum metal mine
A minimum metal mine is a land mine that is designed to use the minimum amount of metal in its construction . Both minimum metal anti-tank and anti-personnel mines exist. Some designs contain almost no metal at all...
antipersonnel mines such as the VS-50
VS-50 mine
The VS-50 is a circular plastic cased anti-personnel blast mine, formerly manufactured by the now-defunct Valsella Meccanotecnica SpA, an Italian high-tech defense industry specialized in area denial systems which was also the manufacturer of the Valmara 69 and one of the first industries in the...
or TS-50
TS-50 mine
The TS-50 is a small circular Italian blast resistant minimum metal anti-personnel mine. The mine has a ribbed plastic case which is olive green, brown or sand colored. The mine has a central raised pressure pad on the top surface of the mine, which can operate even with the mine upside down....
, some of which can also have anti-handling features.
History
History of the Luftwaffe during World War II
The German Luftwaffe was one of the strongest, most doctrinally advanced, and most battle-experienced air forces in the world when World War II started in Europe in September 1939. Officially unveiled in 1935, in violation of the Treaty of Versailles, its purpose was to support Adolf Hitler's...
ZUS-40 anti-removal fuze (of which 3 slightly different versions existed) which was used during the London Blitz and elsewhere. ZUS-40s were designed to fit underneath most Luftwaffe bomb fuzes. When a delayed-action bomb containing a ZUS-40 was dropped on a target, the massive jolt after it hit the ground freed a ball-bearing inside the ZUS-40, thereby arming a spring-loaded firing pin
Firing pin
A firing pin or striker is part of the firing mechanism used in a firearm or explosive device e.g. an M14 landmine or bomb fuze. Firing pins may take many forms, though the types used in landmines, bombs, grenade fuzes or other single-use devices generally have a sharpened point...
. However, so long as the main bomb fuze remained inside its fuze well, the cocked firing pin in the ZUS-40 was prevented from springing forward. ZUS-40s were often fitted underneath a type 17 clockwork
Clockwork
A clockwork is the inner workings of either a mechanical clock or a device that operates in a similar fashion. Specifically, the term refers to a mechanical device utilizing a complex series of gears....
long delay fuze, which gave up to 72 hours delayed detonation
Detonation
Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...
. Rendering safe a type 17 fuze was normally a simple and straightforward process i.e. unscrew the fuze locking ring, remove the fuze from its pocket in the side of the bomb and unscrew the gaine
Explosive booster
An explosive booster acts as a bridge between a low energy explosive and a low sensitivity explosive such as TNT. It increases the explosive shockwave from an initiating explosive to the degree sufficient to detonate the secondary charge.Unlike C4 plastic explosive, not all explosives can be...
. However, fitting a ZUS-40 underneath a type 17 fuze made the render-safe process much more complicated and dangerous. Removing the main time-delay fuze more than 2 cms from its fuze pocket (without neutralising the anti-handling device underneath) automatically released the cocked firing pin inside the ZUS-40, which sprang forward to strike a large percussion cap
Percussion cap
The percussion cap, introduced around 1830, was the crucial invention that enabled muzzleloading firearms to fire reliably in any weather.Before this development, firearms used flintlock ignition systems which produced flint-on-steel sparks to ignite a pan of priming powder and thereby fire the...
, thereby causing detonation
Detonation
Detonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...
of the bomb and the death of anyone kneeling beside it. Because the ZUS-40 was designed to be concealed underneath a conventional bomb fuze, it was very difficult to know whether a particular bomb was fitted with an anti-handling device or not. In any case, many electrically-fired German
Nazi Germany
Nazi Germany , also known as the Third Reich , but officially called German Reich from 1933 to 1943 and Greater German Reich from 26 June 1943 onward, is the name commonly used to refer to the state of Germany from 1933 to 1945, when it was a totalitarian dictatorship ruled by...
bomb fuzes (which could be fitted above a ZUS-40) already had a tiny pendulum based "trembler" device inside them, which closed the circuit and triggered detonation if the bomb was subjected to rough handling. Some German anti-handling fuzes were even more sophisticated and therefore particularly dangerous to EOD personnel e.g. the type 50 and 50BY fuzes. These were normally fitted to 250/500 kg bombs and contained two mercury tilt switch
Mercury switch
A mercury switch is a switch whose purpose is to allow or interrupt the flow of electric current in an electrical circuit in a manner that is dependent on the switch's physical position or alignment relative to the direction of the "pull" of earth's gravity, or other inertia.Mercury switches...
es which detected movement across vertical and horizontal axes. The fuzes fully armed themselves approximately 30 seconds after hitting the ground. Subsequently, if the bomb was moved in any way, the mercury switch completed an electrical circuit and triggered detonation. To complicate matters still further, German bombs could have two separate fuze pockets fitted, with different fuze types screwed into each one. As a result, one bomb could incorporate two separate anti-handling devices working independently of each other e.g. a type 17 clockwork fuze with a ZUS-40 hidden underneath it screwed into one fuze pocket, and a type 50BY in the other. Although the designs of these anti-handling fuzes varied, all were specifically designed to kill bomb disposal personnel who had the task of rendering them safe.
Allied forces developed their own designs of anti-handling devices during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...
. For example, the American M123, M124, M125 and M131 series of long delay tail-fuzes, or the British "Number 37 Long Delay Pistol", were used in air-dropped bombs. These were primarily designed to operate as chemical long-delay fuzes, with time settings ranging between 1 and 144 hours. However, they also contained anti-withdrawal mechanisms designed to kill anyone who tried to render a bomb safe: any attempt to unscrew and remove one of these long-delay fuzes from the fuze pocket of a bomb after it had been dropped would automatically trigger detonation by releasing a cocked firing pin
Firing pin
A firing pin or striker is part of the firing mechanism used in a firearm or explosive device e.g. an M14 landmine or bomb fuze. Firing pins may take many forms, though the types used in landmines, bombs, grenade fuzes or other single-use devices generally have a sharpened point...
which struck a percussion cap connected to an adjacent detonator
Detonator
A detonator is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the latter two being the most common....
. The British nose fuze number 845 Mk 2 (used by RAF Bomber Command
RAF Bomber Command
RAF Bomber Command controlled the RAF's bomber forces from 1936 to 1968. During World War II the command destroyed a significant proportion of Nazi Germany's industries and many German cities, and in the 1960s stood at the peak of its postwar military power with the V bombers and a supplemental...
during World War II) operated purely in anti-disturbance mode. It contained a mercury tilt switch
Mercury Tilt Switch
Mercury Tilt Switch was a rock band from Dundee, Scotland.They formed at the city's university and went through various line up changes before settling on the current line up in 2001. The band have undertaken several tours of the UK and Republic of Ireland and have released two full length albums,...
which triggered detonation if the bomb was moved after a 20 second arming delay, which started when the bomb hit the ground.
Since then, many nations have produced munitions with fuzes which have some form of anti-handling function. Alternatively, they have produced munitions with features which make it very easy to add an anti-tamper function e.g. extra (but empty) threaded fuze wells on anti-tank landmines, into which the detonator
Detonator
A detonator is a device used to trigger an explosive device. Detonators can be chemically, mechanically, or electrically initiated, the latter two being the most common....
s on booby-trap firing devices (plus booster
Explosive booster
An explosive booster acts as a bridge between a low energy explosive and a low sensitivity explosive such as TNT. It increases the explosive shockwave from an initiating explosive to the degree sufficient to detonate the secondary charge.Unlike C4 plastic explosive, not all explosives can be...
attachments) can be screwed.
Classes of anti-handling devices
US Army field manual FM 20-32 classifies four classes of anti-handling devices:- Anti-lifting devices. A device which initiates an explosion when a protected mine is lifted or pulled out of its hole.
- Anti-disturbance device. A device which initiates an explosion when a protected mine is lifted, tilted or disturbed in any way e.g. a notable variant of the VS-50 mineVS-50 mineThe VS-50 is a circular plastic cased anti-personnel blast mine, formerly manufactured by the now-defunct Valsella Meccanotecnica SpA, an Italian high-tech defense industry specialized in area denial systems which was also the manufacturer of the Valmara 69 and one of the first industries in the...
featuring an integral mercury switchMercury switchA mercury switch is a switch whose purpose is to allow or interrupt the flow of electric current in an electrical circuit in a manner that is dependent on the switch's physical position or alignment relative to the direction of the "pull" of earth's gravity, or other inertia.Mercury switches...
. - Anti-defuzing device. A device which initiates an explosion when an attempt is made to remove a fuze from a protected mine.
- Anti-disarming device. A device which initiates an explosion when an attempt is made to set the arming mechanism of a mine to safe.
Types of anti-handling fuzes
The different classes of anti-handling devices are normally created using a variety of fuzes. This is a list of the types of fuzes used as anti-handling devices:- Pull fuzeFuzeFuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...
s — these are typically installed in secondary fuze wells located on the side or bottom of landmines. The fuze is normally connected to a thin wire attached to the ground, so the wire is automatically pulled if the mine is lifted, shifted or disturbed in any way. Simple pull-fuzes release a spring-loaded strikerFiring pinA firing pin or striker is part of the firing mechanism used in a firearm or explosive device e.g. an M14 landmine or bomb fuze. Firing pins may take many forms, though the types used in landmines, bombs, grenade fuzes or other single-use devices generally have a sharpened point...
. More sophisticated versions are electronic i.e. feature a break-wire sensor which detects a drop in voltage. Either way, pulling on the hidden wire triggers detonation. - Anti-lifting fuzeFuzeFuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...
s — these are frequently screwed into an auxiliary fuze pocket located underneath anti-tank landmines. The act of lifting or shifting the mine releases a cocked striker, triggering detonation. The M5 universal firing device is a classic example of an anti-lift fuze. Its standard gauge screw threadScrew threadA screw thread, often shortened to thread, is a helical structure used to convert between rotational and linear movement or force. A screw thread is a ridge wrapped around a cylinder or cone in the form of a helix, with the former being called a straight thread and the latter called a tapered thread...
allows it to be fitted to various munition types. - Tilt/Vibration switches — this is a fuze installed inside the device which triggers detonationDetonationDetonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...
if the sensor is tilted beyond a certain angle or is subject to any vibration. Typically, some form of pendulumPendulumA pendulum is a weight suspended from a pivot so that it can swing freely. When a pendulum is displaced from its resting equilibrium position, it is subject to a restoring force due to gravity that will accelerate it back toward the equilibrium position...
arrangement, spring-loaded "trembler" or mercury switchMercury switchA mercury switch is a switch whose purpose is to allow or interrupt the flow of electric current in an electrical circuit in a manner that is dependent on the switch's physical position or alignment relative to the direction of the "pull" of earth's gravity, or other inertia.Mercury switches...
is used to detect this. - Anti-mine detector fuzes — developed during the Second World War to detect the magnetic fieldMagnetic fieldA magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
of mine detectorsMetal detectorA metal detector is a device which responds to metal that may not be readily apparent.The simplest form of a metal detector consists of an oscillator producing an alternating current that passes through a coil producing an alternating magnetic field...
. - Electronic fuzeFuzeFuze Beverage, commercially referred to as just Fuze , is a manufacturer of teas and non-carbonated fruit drinks enriched with vitamins. Currently the brand consists of five vitamin-infused lines: Slenderize, Refresh, Tea, Defensify, and Vitalize...
s — modern electronic fuzes may incorporate anti-handling features. Typically, these fuzes incorporate one or more of the following sensors: seismic, magnetic, light sensitive, thermal or acoustic sensitive. Potentially, such fuzes can discriminate between various types of mine clearance operations i.e. resist activation by devices such as mine flailMine flailA mine flail is a vehicle-mounted device that makes a safe path through a mine-field by deliberately detonating land mines in front of the vehicle that carries it. They were first used by the British during World War II....
s, plows, or explosives, whilst still detonating when handled by deminingDeminingDemining or mine clearance is the process of removing either land mines, or naval mines, from an area, while minesweeping describes the act of detecting of mines. There are two distinct types of mine detection and removal: military and humanitarian.Minesweepers use many tools in order to accomplish...
personnel. Additionally, electronic fuzes may have an inbuilt self-destructSelf-destructA self-destruct is a mechanism which causes a device to destroy itself under a predefined set of circumstances.Self-destruct mechanisms are also found on devices and systems where malfunction could endanger large numbers of people...
capability i.e. some form of timer countdown designed to trigger detonationDetonationDetonation involves a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations are observed in both conventional solid and liquid explosives, as well as in reactive gases...
hours, days or even months after deployment, possibly whilst people are attempting to render the device safe. Although fuzes with a self-destruct capability are not anti-handling devices per se, they do add an extra complicating factor to the EOD process.