Depending upon the type of target, the fuze may
be required to delay the detonation of the bomb
after impact for a preset time (functioning
delay). Functioning delay may vary from a few
milliseconds to many hours.
It should not detonate the bomb if the bomb is
accidentally released or if the bomb is jettisoned
in a safe condition from the aircraft.
To provide these qualities, a number of design
features are used. Most features are common to all
types of fuzes.
Electrical Fuzes
Electrical fuzes have many characteristics of
mechanical fuzes. They differ in fuze initiation. An
electrical impulse is used to initiate the electrical fuze
rather than the mechanical action of arming vane
rotation.
An electrical pulse from the delivery aircraft
charges capacitors in the fuze as the bomb is released
from the aircraft. Arming and functioning delays are
produced by a series of resistor/capacitor networks in
the fuze. The functioning delay is electromechanically
initiated, with the necessary circuits closed by means of
shock-sensitive switches.
The electric bomb fuze remains safe until it is
energized by the electrical charging system carried in
the aircraft. Because of the interlocks provided in the
release equipment, electrical charging can occur only
after the bomb is released from the rack or shackle and
has begun its separation from the aircraft; however, it is
still connected electrically to the aircraft's bomb arming
unit. At this time, the fuze receives an energizing
charge required for selection of the desired arming and
impact times.
SPECIAL SAFETY FEATURES
Some fuzes incorporate special safety features. The
most important safety features are detonator safe, shear
safe, and delay arming.
Detonator safe fuzes do not have the elements of
their firing train in the proper position for firing until
the fuze is fully armed. The elements remain firmly
fixed and out of alignment in the fuze body while the
fuze is unarmed. This increases safety during shipping,
stowing, and handling of the fuze. The arming action of
the fuze aligns the firing train.
A shear-safe fuze does not become armed if its
arming mechanism is damaged or completely severed
from the fuze body. The arming mechanism of the fuze
protrudes from the bomb, and it might be severed from
the fuze body if the bomb is accidentally dropped.
Shear-safe fuzes give additional security for carrier
operations and for externally mounted bombs.
Delay arming mechanically or electrically slows
the arming of the fuze. It keeps a fuze in the safe
condition until the bomb falls far enough away from or
long enough from the aircraft to minimize the effects of
a premature explosion. Delay arming helps to make
carrier operations safe because a bomb accidentally
released during landing or takeoff ordinarily will not
have sufficient air travel, velocity, or time to fully arm
the fuze.
REVIEW NUMBER 1
Q1.
Name the device that controls bomb
detonation.
Q2.
The time or number of vane revolutions
needed for the firing train to align after a
bomb is released is the _______.
Q3.
Describe the functioning time of a fuze.
Q4.
The distance along the trajectory that a bomb
travels from the releasing aircraft in an
unarmed condition is the ____________.
Q5.
List the two basic classes of fuzes.
Q6.
Describe
the
basic
principle
of
the
mechanical fuze.
Q7.
What means is used to initiate an electrical
fuze?
Q8.
List the three special safety features incor-
porated into fuzes.
MECHANICAL FUZES
LEARNING
OBJECTIVE:
Identify
the
various types of mechanical fuzes to include
their physical description and functional
operation.
There are many fuzes in use by the Navy today.
Some of the commonly used fuzes are discussed in this
TRAMAN. To keep up with current fuzes, you should
refer to Aircraft Bombs, Fuzes, and Associated
Components, NAVAIR 11-5A-17, and Airborne Bomb
and Rocket Fuze Manual, NAVAIR 11-1F-2.
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