Tuesday, February 13, 2007

Cluster Bomb (Bomb)

Cluster munitions or cluster bombs are air-dropped or ground-launched munitions that eject a number of smaller submunitions: a cluster of bomblets. The most common types are intended to kill enemy personnel and destroy vehicles. Submunition based weapons designed to destroy runways, electric power transmission lines, deliver chemical or biological weapons, or to scatter land mines have also been produced. Some submunition based weapons can disperse non-munition payloads, such as leaflets.

Because cluster bombs release many small unexploded bomblets over a wide area, they can kill or maim civilians long after a conflict has ended. Unexploded submunitions are very costly to locate and remove.

Cluster bombs are prohibited under the Convention on Cluster Munitions, which was adopted in Dublin in May 2008 and will open for signature in December 2008. The general rules of international humanitarian law aimed at protecting civilians also apply to cluster bombs as they do to all weapons.

Development

The first cluster bomb used operationally was the German SD-2 or Sprengbombe Dickwandig 2 kg, commonly referred to as the Butterfly Bomb. It was used during the Second World War to attack both civilian and military targets. The technology was developed independently by the United States of America, Russia and Italy. Cluster bombs are now standard air-dropped munitions for many nations, in a wide variety of types. Currently produced by 34 countries and used by at least 23.

Artillery shells that employ similar principles have existed for decades. They are typically referred to as ICM (Improved Conventional Munitions) shells. The US military slang terms for them are "firecracker" or "popcorn" shells, for the many small explosions they cause in the target area.

Types of cluster bombs

A basic cluster bomb is a hollow shell containing from three to more than 2,000 submunitions. Some types are dispensers that are designed to be retained by the aircraft after releasing their munitions. The submunitions themselves may be fitted with small parachute retarders or streamers to slow their descent (allowing the aircraft to escape the blast area in low-altitude attacks).

Modern cluster bombs and submunition dispensers are often multiple-purpose weapons, containing mixtures of anti-armor, anti-personnel, and anti-material munitions. The submunitions themselves may also be multi-purpose, such as combining a shaped charge, to attack armour, with a fragmenting case, to attack infantry, material, and light vehicles. Modern multipurpose munitions may have an incendiary effect.

A growing trend in the design of submunition-based weapons is the smart submunition, which uses guidance circuitry to locate and attack particular targets, usually armored vehicles. Recent weapons of this type include the U.S. CBU-97 sensor-fused weapon, first used in combat during the 2003 invasion of Iraq. Munitions specifically intended for anti-tank use may be set to self-destruct if they reach the ground without locating a target, theoretically reducing the risk of unintended civilian deaths and injuries. Although smart submunition weapons are many times more expensive than standard cluster bombs, which are cheaper and simpler to manufacture, far fewer smart submunitions are required for defeating dispersed and mobile targets in an area, offsetting this cost.

Incendiary

Incendiary cluster bombs are intended to start fires, just as conventional incendiary bombs (also called firebombs). They are specifically designed for this purpose, with submunitions of white phosphorus or napalm, and they often include anti-personnel and anti-tank submunitions to hamper firefighting efforts. When used in cities they have often been preceded by the use of conventional explosive bombs to break open the roofs and walls of buildings to expose flammable contents to the incendiaries. One of the earliest examples is the so-called Molotov bread basket first used by the Soviet Union in the Winter War of 1939-40. This type of munition was extensively used by both sides in the strategic bombings of World War II. Bombs of this type were used to start firestorms in cases such as the bombing of Dresden in World War II and the firebombing of Tokyo. A modern development of the incendiary cluster bomb is the thermobaric weapon. In these types of weapons, submunitions are used to deliver a highly combustible aerosol, which is subsequently ignited, resulting in a high pressure explosion.

Anti-personnel

Anti-personnel cluster bombs use explosive fragmentation to kill troops and destroy soft (unarmored) targets. Along with incendiary cluster bombs, these were among the first forms of cluster bombs produced by Germany during World War II. They were famously used during the Blitz with delay and booby-trap fusing to prevent firefighting and other damage control efforts in the bombed areas. They were also used with a contact fuse when attacking entrenchments. These weapons were most widely used during the Vietnam War when many thousands of tons of submunitions were dropped on Laos, Cambodia and Vietnam.

The CBU-24 (Cluster Bomb Unit-24) is a weapon developed by the United States for anti personnel purposes.

The weapon contains 665 BLU-26 tennis ball-sized submunitions, each designed to detonate with 600 metal fragments for an anti-personnel / anti-materiel effect.

Anti-tank

Most anti-armor munitions contain shaped charge warheads to pierce the armor of tanks and armored fighting vehicles. In some cases, guidance is used to increase the likelihood of successfully hitting a vehicle. Modern guided submunitions, such as those found in the U.S. CBU-97 can use either a shaped charge warhead or an explosively formed penetrator. Unguided shaped-charge submunitions are designed to be effective against entrenchments that incorporate overhead cover. To simplify supply and increase battlefield effectiveness by allowing a single type of round to be used against nearly any target, submunitions that incorporate both fragmentation and shaped-charge effects are produced. In United States Army and Marine Corps Field Artillery units, this is a common type of shell used in ground warfare.

Anti-runway

Anti-runway submunitions such as the British JP233 are designed to penetrate concrete before detonating, allowing them to shatter and crater runway surfaces. In the case of the JP233, the cratering effect is achieved through the use of a two-stage warhead that combines a shaped charge and conventional explosive. The shaped charge creates a small crater inside which the conventional explosive detonates to enlarge it. Anti-runway submunitions are usually used along with anti-personnel submunitions equipped with delay or booby-trap fuses that act as anti-personnel mines to make repair more difficult.

Mine-laying

When submunition-based weapons are used to disperse mines, their submunitions do not detonate immediately, but behave like conventional land mines that detonate later. The submunitions usually include a combination of anti-personnel and anti-tank mines. Since such mines usually lie on exposed surfaces, the anti-personnel forms, such as the US Area Denial Artillery Munition normally deploy tripwires automatically after landing to make clearing the minefield more difficult. In order to avoid rendering large portions of the battlefield permanently impassable, and to minimize the amount of mine-clearing needed after a conflict, scatterable mines used by the United States are designed to self-destruct after a period of time from 4-48 hours. The internationally agreed definition of cluster munitions being negotiated in the Oslo Process may not include this type of weapon, since landmines are already covered in other specific international instruments.

Chemical weapons

During the 1950s and 1960s, the United States and Soviet Union developed cluster weapons designed to deliver chemical weapons. The Chemical Weapons Convention of 1993 banned their use. Six nations declared themselves in possession of chemical weapons. The US and Russia are in the process of destroying their stockpiles, although they have received extensions for the full destruction.

Anti-electrical

An anti-electrical weapon, the CBU-94/B, was first used by the U.S. in the Kosovo War in 1999. These consist of a TMD (Tactical Munitions Dispenser) filled with 202 BLU-114/B submunitions. Each submunition contains a small explosive charge that disperses 147 reels of fine conductive fiber, either carbon fiber or aluminum-coated glass fiber. Their purpose is to disrupt and damage electric power transmission systems by producing short circuits in high-voltage power lines and electrical substations. On the first attack, these knocked out 70% of the electrical power supply in Serbia. There are reports that it took 500 people 15 hours to get one transformer yard back on line after being hit with the conductive fibers.

Leaflet dispensing

The LBU-30 is designed for dropping large quantities of leaflets from aircraft. (Dispensing leaflets from the air is a common propaganda tactic in wartime.) Enclosing the leaflets within the bomblets ensures that the leaflets will fall on the intended area without being dispersed excessively by the wind. The LBU-30 consists of SUU-30 dispensers that have been adapted to leaflet dispersal. The dispensers are essentially recycled units from old bombs. The LBU-30 was tested at Eglin Air Force Base in 2000, by an F-16 flying at 20,000 feet (6,100 m).

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