Bombs for Beginners

Stabilizing Devices

Damage Mechanisms

There are five general categories of munitions damage mechanisms: blast, fragmentation, cratering, shaped charge penetration, and incendiary effects. A given target is usually most vulnerable to one particular damage mechanism, though it may be vulnerable (to a lesser extent) to several damage mechanisms. The factors governing determination of the primary damage mechanism for a given target are: target construction, target location (relative to the point of warhead detonation), warhead damage effects pattern, and the desired type and level of damage.

Blast is caused by tremendous dynamic overpressures generated by the detonation of a high explosive. Complete (high order) detonation of high-explosives can generate pressures up to 700 tons per square inch and temperatures in the range of 3,000 to 4,500º prior to bomb case fragmentation. It is essential that the bomb casing remain intact long enough after the detonation sequence begins to contain the hot gases and achieve a high order explosion. A consideration when striking hardened targets is that deformation of the weapon casing or fuze may cause the warhead to dud or experience a low order detonation. Approximately half of the total energy generated will be used in swelling the bomb casing to 1.5 times its normal size prior to fragmenting and then imparting velocity to those fragments. The remainder of this energy is expended in compression of the air surrounding the bomb and is responsible for the blast effect. This effect is most desirable for attacking walls, collapsing roofs, and destroying or damaging machinery. The effect of blast on personnel is confined to a relatively short distance (110 feet for a 2000 pound bomb). For surface targets blast is maximized by using a general purpose (GP) bomb with an instantaneous fuzing system that will produce a surface burst with little or no confinement of the overpressures generated by excessive burial. For buildings or bunkers the use of a delayed fuzing system allows the blast to occur within the structure maximizing the damage caused by the explosion.

Fragmentation is caused by the break-up of the weapon casing upon detonation. Fragments of a bomb case can achieve velocities from 3,000 to 11,000 fps depending on the type of bomb (for example GP bomb fragments have velocities of 5,000 to 9,000 fps). Fragmentation is effective against troops, vehicles, aircraft and other soft targets. The fragmentation effects generated from the detonation of a high-explosive bomb have greater effective range than blast, usually up to approximately 3,000 feet regardless of bomb size. The fragmentation effect can be maximized by using a bomb specifically designed for this effect, or by using a GP bomb with an airburst functioning fuze.

The cratering effect is normally achieved by using a GP bomb with a delayed fuzing system. This system allows bomb penetration before the explosion. Since the explosion occurs within the surface media the energy of the blast is causes the formation of a crater. This effect is most desirable in interdiction of lines of communication (LOC) and area denial operations

Armor penetration is accomplished by shaped charges or kinetic energy penetrators. This is an effective damage mechanism for tanks, assault guns, armored personnel carriers, and other armored targets. A major problem associated with both shaped charges and kinetic energy penetrators is the lack of visible damage. This may result in repeated attacks to produce battlefield evidence that a target is no longer a threat.

Fire is effective in interrupting operations of enemy personnel and in damaging supplies stored in the open. Incendiaries produce intense, localized heat designed to ignite adjacent combustible target materials. The true incendiary produces no fireball and relatively little flame. The basic damage mechanism of firebomb weapons comes from the fireball and burning residual fuel globules, impact momentum of the fuel and container, and damage from fires started by the weapon. The sharp cutoff of casualty-producing mechanisms outside the incendiary pattern allows delivery close to friendly troops, usually parallel to the forward line of battle, with minimum risk. Munitions have been developed with full fragmentation and penetrating capabilities coupled with reactive incendiary devices. These improved incendiaries are highly effective against fuel and other flammable targets. A drawback, however, in planning for the employment of incendiary weapons is that incendiary/fire effects are not evaluated in current weaponeering methodologies.

WEAPONS HIT CRITERIA

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