Bomb

I

Introduction

Bomb, device containing explosives, chemicals, or other materials, designed to be detonated in the region of a target so as to kill people or cause damage by blast, heat, shrapnel, or other effects. Bombs are the most destructive weapons so far devised. They are an essential component of warfare as well as being used increasingly by terrorists.

The two basic types of bombs are conventional and nuclear. Conventional bombing from aircraft began as early as 1911, when Italian aviators attacked Arab forces in Libya during the Italo-Turkish War. Almost 2 million tons of bombs were dropped on Germany by Allied forces during World War II. Nuclear weapons, which were used by the United States against the Japanese cities of Hiroshima and Nagasaki in World War II, are far more destructive and are based on the principles of atomic fission and fusion. Conventional bombs are made of chemical explosives, which depend on the release of energy from the atom's electrons, while nuclear bombs release vast amounts of nuclear energy from atoms of uranium or plutonium.

Bombs are delivered by specially equipped aircraft against enemy troops, tanks, fortifications, industrial plants, or cities. A bomb discharged against a submarine is called a depth charge. Bombs can be dropped from high altitudes, released from an aircraft approaching the target at low altitude, or lofted at the target. Before the advent of air warfare, shells fired by artillery pieces were designated bombs but are now known as projectiles. The term “bomb” is also applied to small, relatively simple explosive devices planted or aimed manually, such as those used by terrorists. When carried on a missile, a bomb is known as a warhead.

II

Conventional Bombs

Conventional bombs, comprising high explosive, incendiary, and chemical or biological types, generally have cylindrical metal bodies filled with explosives or chemicals. They range in weight from about 2 kg (4.4 lb) up to about 1,360 kg (3,000 lb), depending on type and intended use. The nose is pointed or rounded, with fins at the rear to stabilize flight and retardation panels to slow down the bomb's fall. Bombs are detonated by various types of fuses that become armed, that is, activated to explode, only after release from the aircraft. The fuses are commonly designed to explode on impact with the target (contact fuse), but they may also be set for aerial explosion over the target (proximity fuse), or for delayed detonation at a predetermined time after impact (time fuse).

A

General-Purpose Bombs

General-purpose bombs are used against troops and emplacements or on cities. They usually contain the high explosive TNT (trinitrotoluene), sometimes combined with other explosives such as cyclonite (RDX) and ammonium nitrate. Among the destructive effects that wreak devastation are the blast wave of air pressure immediately following the explosion, which blows down buildings and other structures and smashes windows; fragmentation of pieces of the bomb, which fly at high speed into people and buildings; and shock waves through the area of land or sea where the bomb has exploded. These effects are also applicable to nuclear bombs, which have an additional effect (radiation). Some of the largest general-purpose bombs—weighing over 6,000 kg—were used by the US Army during the Vietnam War to defoliate vast areas.

B

Fragmentation Bombs

Fragmentation bombs explode and distribute metal splinters, and are used against troop concentrations. Cluster bombs dropped from aircraft scatter dozens of small “bomblets” over a target area, some exploding on contact and others only when disturbed later by people or vehicles, killing by fragmentation. Armour-piercing bombs, equipped with a hard steel nose which penetrates and destroys warships, are among special-purpose or delayed-action bombs for use against tanks, ships, and buildings.