BOMBS, FUZES, AND ASSOCIATED
Bombs must be manufactured to withstand
reasonable heat and be insensitive to the shock of
ordinary handling. They must also be capable of being
dropped from an aircraft in a safe condition when
in-flight emergencies occur.
Bomb detonation is controlled by the action of a
fuze. A fuze is a device that causes the detonation of an
explosive charge at the proper time after certain
conditions are met. A bomb fuze is a mechanical or an
electrical device. It has the sensitive explosive elements
(the primer and detonator) and the necessary
mechanical/electrical action to detonate the main
burster charge. The primer is fired by a mechanical
action or an electrical impulse, which causes the
detonator to explode. The primer-detonator explosion
is relayed to the main charge by a booster charge. This
completes the explosive train.
FUZE TERMINOLOGY AND BASIC
LEARNING OBJECTIVE: Describe the
operation of mechanical and electrical fuzes.
Identify special safety features that are inherent
in bomb fuzes.
This chapter will introduce you to some of the
common terms and acronyms associated with fuzes used
in the Navy. Basic fuze theory, general classes of fuzes,
and the various types of fuzes are also discussed in this
Delay. When the functioning time of a fuze is
longer than 0.0005 second.
External evidence of arming (EEA). A means by
which a fuze is physically determined to be in a safe or
Functioning time. The time required for a fuze to
detonate after impact or a preset time.
Instantaneous. When the functioning time of a fuze
is 0.0003 second or less.
Nondelay. When the functioning time of a fuze is
0.0003 to 0.0005 second.
Proximity (VT). The action that causes a fuze to
detonate before impact when any substantial object is
detected at a predetermined distance from the fuze.
Safe air travel (SAT). The distance along the
trajectory that a bomb travels from the releasing aircraft
in an unarmed condition.
BASIC FUZE THEORY
Fuzes are normally divided into two general
classes-mechanical and electrical. These classes only
refer to the primary operating principles. They maybe
subdivided by their method of functioning or by the
action that initiates the explosive trainimpact,
mechanical time, proximity, hydrostatic, or long delay.
Another classification is their position in the
bomb-nose, tail, side, or multipositioned. Mechanical
and electrical fuzes are discussed in the following text.
Some of the most common fuze terms that you
should know are defined as follows:
The amount of time or vane
revolutions needed for the firing train to be aligned after
the bomb is released, or from time of release until the
bomb is fully armed. It is also known as safe separation
In its simplest form, a mechanical fuze is like the
hammer and primer used to fire a rifle or pistol. A
mechanical force (in this case, the bomb impacting the
target) drives a striker into a sensitive detonator. The
detonator ignites a train of explosives, eventually firing
the main or filler charge. A mechanical bomb fuze is
more complicated than the simple hammer and primer.
For safe, effective operation, any fuze (mechanical or
electrical) must have the following design features: