It must remain safe in stowage, while it is handled
in normal movement, and during loading and
It must remain safe while being carried aboard
It must remain safe until the bomb is released and
is well clear of the delivery aircraft (arming delay
or safe separation period).
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
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
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
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 electrical y to the aircrafts bomb arming
unit. At this time, the fuze receives an energizing charge
required for selection of the desired arming and impact
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
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
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
REVIEW NUMBER 1
Name the device that controls bomb detonation.
The time or number of vane revolutions needed
for the firing train to align after a bomb is
released is the ________.
Describe the functioning time of a fuze.
The distance along the trajectory that a bomb
travels from the releasing aircraft in an unarmed
condition is the________.
List the two basic classes of fuzes.
Describe the basic principle of the mechanical
What means is used to initiate an electrical fuze ?
List the three special safety features
incorporated into fuzes.