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.

C.

Incendiary Bombs

Incendiary bombs, or firebombs, much used in World War II, are designed to ignite flammable structures and contain petrol compounds. Small bombs can be dropped by the hundreds to start fire storms. Another type of incendiary device, the napalm bomb, is used against dug-in enemy forces. Spreading an explosive of jellied petrol, it not only causes severe burns but consumes the oxygen in any closed space. Fuel-air bombs, which were also used in the Vietnam War to burn large areas of jungle and blow up buried mines, spread an igniting cloud of explosive fuel.

D.

Chemical and Biological Weapons

The other two types of conventional bombs, chemical (gas) and biological weapons, depend on the dispersal of the contents of a delivery canister rather than on the direct effects of an explosive. Bombs can also be used to deliver incapacitating, toxic, or nerve gases against enemy concentrations to decrease their resistance to attack, or to destroy them. Non-lethal gases cause mental confusion and also reduce the effectiveness of enemy forces by making necessary the deployment of other personnel to provide assistance to those incapacitated. Biological weapons also incapacitate or kill, but their effects may be more widespread and of longer duration.