4.21 FUSE IGNITION
The oldest form of explosive ignition, fuses are perhaps the favorite
type of simple ignition system. By simply placing a piece of waterproof fuse in
a device, one can have almost guaranteed ignition. Modern waterproof fuse is
extremely reliable, burning at a rate of about 2.5 seconds to the inch. It is
available as model rocketry fuse in most hobby shops, and costs about $3.00 for
a nine-foot length. Fuse is a popular ignition system for pipe bombers because
of its simplicity. All that need be done is light it with a match or lighter.
Of course, if the Army had fuses like this, then the grenade, which uses
fuse ignition, would be very impracticle. If a grenade ignition system can be
acquired, by all means, it is the most effective. But, since such things do not
just float around, the next best thing is to prepare a fuse system which does
not require the use of a match or lighter, but still retains its simplicity.
One such method is described below:
Suppose an eight inch piece of fuse is burned, and its complete time of combustion is 20 seconds.
20 seconds
---------- = 2.5 seconds per inch.
8 inches
If a delay of 10 seconds was desired with this fuse, divide the desired
time by the number of seconds per inch:
10 seconds
------------------ = 4 inches
2.5 seconds / inch
NOTE: THE LENGTH OF FUSE HERE MEANS LENGTH OF FUSE TO THE POWDER. SOME FUSE,
AT LEAST AN INCH, SHOULD BE INSIDE THE DEVICE. ALWAYS ADD THIS EXTRA
INCH, AND PUT THIS EXTRA INCH AN INCH INTO THE DEVICE!!!
_____________________
\ /
\ / ------ match book cover
\ /
| M|f|M ---|------- match head
| A|u|A |
| T|s|T |
| C|e|C |
|tapeH|.|Htape|
| |f| |
|#####|u|#####|-------- striking paper
|#####|s|#####|
\ |e| /
\ |.| /
\ |f| /
\ |u| /
|ta|s|pe|
|ta|e|pe|
|.|
|f|
|u|
|s|
|e|
|.|
|_|
The match book is wrapped around the matches, and is taped to itself.
The matches are taped to the fuse. The striker will rub against the
matcheads when the match book is pulled.
The best and most reliable impact initiator is one that uses factory made initiators or primers. A no. 11 cap for black powder firearms is one such primer. They usually come in boxes of 100, and cost about $2.50. To use such a cap, however, one needs a nipple that it will fit on. Black powder nipples are also available in gun stores. All that a person has to do is ask for a package of nipples and the caps that fit them. Nipples have a hole that goes all the way through them, and they have a threaded end, and an end to put the cap on. A cutaway of a nipple is shown below:
________________
| |
_ |
| | |
_______| |^^^^^^^^| |
| ___________| |
| | |
no. 11 |_______| |
percussion _______ | ------- threads for screwing
cap here | | | nipple onto bomb
| |___________ |
|_______ | |
| |^^^^^^^^^| |
|_| |
|
|________________|
When making using this type of initiator, a hole must be drilled into
whatever container is used to make the bomb out of. The nipple is then screwed
into the hole so that it fits tightly. Then, the cap can be carried and placed
on the bomb when it is to be thrown. The cap should be bent a small amount
before it is placed on the nipple, to make sure that it stays in place. The
only other problem involved with an impact detonating bomb is that it must
strike a hard surface on the nipple to set it off. By attaching fins or a small
parachute on the end of the bomb opposite the primer, the bomb, when thrown,
should strike the ground on the primer, and explode. Of course, a bomb with
mercury fulminate in each end will go off on impact regardless of which end it
strikes on, but mercury fulminate is also likely to go off if the person
carrying the bomb is bumped hard.
4.23 ELECTRICAL IGNITION
Electrical ignition systems for detonation are usually the safest and
most reliable form of ignition. Electrical systems are ideal for demolition
work, if one doesn't have to worry so much about being caught. With two spools
of 500 ft of wire and a car battery, one can detonate explosives from a "safe",
comfortable distance, and be sure that there is nobody around that could get
hurt. With an electrical system, one can control exactly what time a device
will explode, within fractions of a second. Detonation can be aborted in less
than a second's warning, if a person suddenly walks by the detonation sight, or
if a police car chooses to roll by at the time. The two best electrical igniters
are military squibs and model rocketry igniters. Blasting caps for construction
also work well. Model rocketry igniters are sold in packages of six, and cost
about $1.00 per pack. All that need be done to use them is connect it to two
wires and run a current through them. Military squibs are difficult to get,
but they are a little bit better, since they explode when a current is run
through them, whereas rocketry igniters only burst into flame. Military squibs
can be used to set off sensitive high explosives, such as R.D.X., or potassium chlorate mixed with petroleum jelly. Igniters can be used to set off
black powder, mercury fulminate, or guncotton, which in turn, can set of a high order
explosive.
4.24 ELECTRO-MECHANICAL IGNITION
Electro-mechanical ignition systems are systems that use some type of
mechanical switch to set off an explosive charge electrically. This type of
switch is typically used in booby traps or other devices in which the person
who places the bomb does not wish to be anywhere near the device when it
explodes. Several types of electro-mechanical detonators will be discussed.
4.241 Mercury Switches
Mercury switches are a switch that uses the fact that mercury metal
conducts electricity, as do all metals, but mercury metal is a liquid at
room temperatures. A typical mercury switch is a sealed glass tube with
two electrodes and a bead of mercury metal. It is sealed because of mercury's
nasty habit of giving off brain-damaging vapors. The diagram below may help
to explain a mercury switch.
______________
A / \ B
_____wire +______/___________ \
\ ( Hg ) | /
\ _(_Hg_)__|___/
|
|
wire - |
|
|
When the drop of mercury ("Hg" is mercury's atomic symbol) touches both
contacts, current flows through the switch. If this particular switch was in
its present position, A---B, current would be flowing, since the mercury can
touch both contacts in the horizontal position.If, however, it was in the | position, the drop of mercury would only touch the + contact on the A side. Current, then couldn't flow, since mercury does not reach both contacts when the switch is in the vertical position.
This type of switch is ideal to place by a door. If it were placed in the path of a swinging door in the verticle position, the motion of the door would knock the switch down, if it was held to the ground by a piece if tape. This would tilt the switch into the verticle position, causing the mercury to touch both contacts, allowing current to flow through the mercury, and to the igniter or squib in an explosive device. Imagine opening a door and having it slammed in your face by an explosion.
4.242 Tripwire Switches
A tripwire is an element of the classic booby trap. By placing a nearly
invisible line of string or fishing line in the probable path of a victim, and
by putting some type of trap there also, nasty things can be caused to occur.
If this mode of thought is applied to explosives, how would one use such a
tripwire to detonate a bomb. The technique is simple. By wrapping the tips of
a standard clothespin with aluminum foil, and placing something between them,
and connecting wires to each aluminum foil contact, an electric tripwire can
be made, If a piece of wood attached to the tripwire was placed between the
contacts on the clothespin, the clothespin would serve as a switch. When the
tripwire was pulled, the clothespin would snap together, allowing current to
flow between the two pieces of aluminum foil, thereby completing a circuit,
which would have the igniter or squib in it. Current would flow between
the contacts to the igniter or squib, heat the igniter or squib, causing it
it to explode.
__________________________________
\_foil___________________________/
Insert strip of ----------------------------spring
wood with trip- _foil__________________________
wire between foil /_______________________________\
contacts.
Make sure that the aluminum foil contacts do not touch the spring, since
the spring also conducts electricity.
4.243 Radio Control Detonators
In the movies, every terrorist or criminal uses a radio controlled
detonator to set off explosives. With a good radio detonator, one can be
several miles away from the device, and still control exactly when it explodes,
in much the same way as an electrical switch. The problem with radio detonators
is that they are rather costly. However, there could possibly be a reason that
a terrorist would wish to spend the amounts of money involved with a RC (radio
control) system and use it as a detonator. If such an individual wanted to
devise an RC detonator, all he would need to do is visit the local hobby store
or toy store, and buy a radio controlled toy. Taking it back to his/her abode,
all that he/she would have to do is detach the solenoid/motor that controls the
motion of the front wheels of a RC car, or detach the solenoid/motor of the
elevators/rudder of a RC plane, or the rudder of a RC boat, and re-connect the
squib or rocket engine igniter to the contacts for the solenoid/motor. The
device should be tested several times with squibs or igniters, and fully
charged batteries should be in both he controller and the receiver (the part
that used to move parts before the device became a detonator).