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I can't even count how many people
have told me stories of how they loaded a shell into the mortar incorrectly,
only to have
On this page you'll learn
about how all of the different types of consumer fireworks work. Unlike
the other sections, this page lists the fireworks in order of complexity - the
most basic types of fireworks will be listed first, followed by the more complex
ones.
Warning:
the cutaway diagrams shown below are for educational purposes only. They
should not be used as a guide for constructing your own fireworks.
Never attempt to take apart fireworks.
AERIAL/CAKE
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Repeating aerials are just
as complex as aerial shells because that's basically what a repeater is
- many tubes of mini-"shells" all in one unit. These
clusters of tubes each have a clay plug in the bottom and a black powder
lift charge. There are two holes in the side of each tube, and as
the device is being
constructed, small chunks of fuse are used to connect each tube
to its neighbor. This way, when the first lift charge ignites and
sends the effect into the air, the tube next to it ignites shortly
afterwards, and so on. Most devices have several parallel-fused
tubes towards the end of the "fire trail", so that several
tubes ignite simultaneously (or in very rapid succession) at the end of
the performance in order to intensify the display. |
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| Repeaters contain smaller
"effect tubes" that are usually about one-third to half the
length of the main "launching tubes". Each of these has a
construction very similar to a shell. When the lift charge in the
launching tube fires, it ignites a time fuse and (usually) a colored star
composition in the bottom of the effect tube. The star composition
burns brightly as the tube rises, and at the at its maximum altitude, the
burst charge ignites the effects. The diagram at the right shows
stars, which would look like a small, uneven shell burst when ignited.
But if you have ever lit off a repeater before, you would know that there
are dozens of possible effects: effects tubes that go up and explode, ones
that whistle, ones that crackle, ones that spin around on the way up, and
even ones that give off parachutes. Next time you light a repeater,
come back to that area the next morning and look at the ground around
where you set it off - you will see dozens of these spent effects tubes
(with nothing but the clay plug left). |
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AERIAL SHELLS
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Aerial shells are one of the
most beautiful and certainly one of the most complex types of fireworks.
A shell consists of main parts: a container, a lift charge, a time fuse,
a burst charge, and stars/effects. The container, or shell casing,
is a strong wall that protects the contents. The lift charge
propels the shell out of the tube, and the time fuse ignites the burst
charge at the right altitude. The burst charge then ignites the
effects.
Shells are launched from a tube known
as a mortar. A string loop is often attached to consumer firework
shells so it can lowered into the mortar by the fuse. When the
fuse enters the shell, it ignites the burst charge, creating an
explosion that ignites the time fuse and shoots the shell high into the
air.
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As the shell ascends, the time fuse burns
towards the burst charge. At the precise altitude - usually where the
shell is briefly hanging in the air - the time fuse ignites the black powder
burst charge, causing the shell to explode. The powerful explosion blasts
apart the shell casing and ignites the stars, scattering them in all directions
across the sky. These stars burn brightly and give off sparks, creating a
huge spherical pattern in the sky.
DISPLAY TUBES
| Repeating aerial tube devices
are little more than several aerial shells fused together to go off in
sequence, with a few seconds of delay between each shell. There are
usually anywhere from 3 to 7 tubes which are glued down to a thick wooden
base to stabilize the device. Each tube contains a typical aerial
shell in the bottom, protected by a cardboard disk and a cap at the top of
the tube. Holes are drilled in the bottom of each tube, and small
chunks of fuse connect each shell to the tube adjacent to it. The
tube on the end has a long fuse that runs outside for a few inches.
When that fuse is lit, the first shell
fires. The lift charge of that shell ignites the chunk of fuse
leading into the next tube, which in turn ignites a shell about four
seconds later, and so on.
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FIRECRACKERS
| Firecrackers
are the simplest and oldest of fireworks. A single firecracker is
simply a paper tube of several layers to give it strength. It is
plugged at both ends with a dry clay-like substance, and contains a
small amount of flash powder in the middle. When the fire from the
fuse ignites the flash powder, it creates a large volume of hot gas in a
short period of time. The casing of the tube contains this gas
until the pressure blasts the tube open with a loud "crack" |
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FLYING SPINNERS
(HELICOPTERS)
| Flying spinners are another
one of the most popular fireworks. It is little more than a ground
spinner with a paper or plastic wing unit attached to the tube.
When the propellant composition is ignited, it creates thrust which
spins the device around. But whereas a ground spinner would simply
bump around on the ground, the spinning motion of a flying
spinner causes the angled wings to direct airflow downward, lifting the
device into the air exactly like a helicopter (hence the name).
Helicopters have a burst charge at the
end of the propellant compound, which explodes at the end of the
device's flight and ejects stars, ladyfingers, or a parachute.
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FOUNTAINS
| Single tube fountains
consist of a cardboard tube (which may be inside of a cone) that stands
vertically on a plastic base. The tube is charged with a
composition designed to make lots of sparks, flame, and gas. At
the end of the tube there is a clay plug with a hole drilled into it,
forming what is known as a "choke". Without a choke, the
fountain would only give off a weak spray of sparks. With a choke,
however, a lot of pressure builds up inside of the tube, which forces
the gas and sparks out of the fountain with a much greater velocity.
Very small fountain tubes (i.e., 1/4 in diameter) don't require chokes.
The fountain composition is often
layered as to produce different effects at different stages in the
burning. For instance, one layer may burn to produce orange
sparks, followed by a layer that produces white sparks and green star
fragments.
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GROUND SPINNERS
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Single tube ground spinners
consist of a single tube (imagine that!) that is plugged at both ends
with clay and is filled with a rapidly-burning composition. A
small fuse hole has been drilled into the side of the tube, near one of
the ends. When the fuse ignites the composition, hot gases are
produced and rush out of the hole, propelling the device around its
central axis. Because it is off-balance and doesn't have quite
enough thrust to fly, the firework spins wildly and randomly on the
ground. The characteristic blossom shape of Ground Bloom
Flowers is caused by the tube rapidly bumping up and down as it
spins. |
MINES
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Mines are basically a
ground-level aerial shell burst that is directed upwards. The bottom
of the tube contains a black powder lift charge, similar to that found in
a shell. When ignited, the lift charge engulfs the stars in flame,
igniting them as it propels them out of the tube in a V-shaped pattern.
The "spread" of the stars in the sky depends on both the length
and the width of the mortar.
Consumer mines are typically
one-shot-per-tube devices that are bunched together, resembling repeaters.
Professional mines, however, are reloadable - the lift powder and stars
are put in bags, which are lowered into the mortars and ignited.
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NOVELTIES
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There are hundreds of
different novelties, and they all work more or less the same way.
The example I've chosen to illustrate here is the ever-popular tank.
Tanks contain several tiny fountains
that shoot multi-colored stars and often produce just enough thrust to
move the device along if it's placed on a hard, level face. A
small length of gray tissue firecracker-type fuse transfers the fire
from the rear fountain to the front "guns" of the tank.
These small fountains are only filled half way with composition, so the
fuse can therefore enter from the side in order to ignite it.
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PARACHUTES
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Aerial parachutes have a
complex internal construction very similar to that of an aerial shell.
Parachutes can come in the form of single tubes with a base, or clusters
of tubes that look like a tall repeater. The launch tube is usually
quite thick to withstand the forces of the powerful, noisy lift charge.
When the lift charge ignites, it blasts a "parachute tube" high
into the air. Meanwhile, a time fuse is burning inside of the
parachute tube, which in turn ignites a tiny burst charge when the
tube reaches the highest point in its flight. |
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| Much like a model
rocket, this burst (or "ejection") charge blasts the parachutes
from the parachute tube. There is often a small piece of paper
"wadding" between the burst charge and the parachutes to prevent
the chutes from burning up. The tissue parachutes are attached to
small chunks of tube filled with clay to serve as weights. They can
be packed together tightly, which enables several parachutes to be put
inside of one parachute tube.
Sometimes the weight tube is filled with
a smoke composition. A short piece of fuse transfers fire from the
parachute tube's burst charge to the composition in the weight, which
smokes as it drifts down from the sky. Nighttime parachutes use a
steady-burning star or strobe composition in place of smoke composition.
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REPEATING
FOUNTAINS
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Repeating fountains are
large tubes that contain many single fountains that are fused to ignite
sequentially. Because of this, repeating fountains last much
longer and usually have a wider variety of effects than single-tube
fountains.
Each of the individual fountain tubes
has a hole near the bottom with a fuse coming out of it, which leads up
to the top of the next tube. This fuse ignites when the tube has
almost finished burning, and by the time it does, the next tube has
already ignited. This sequence continues for the remainder of the
tubes. Sometimes a fuse will lead to several tubes, igniting them
all at once to produce an intense spray of noise and color as a sort of
'finale'.
Click
here to see an actual picture of the
fusing of a repeating fountain.
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ROCKETS &
MISSILES
| Rockets are the second
oldest type of firework that were originally discovered by mistake - the
Chinese discovered that an open-ended firecracker propelled itself along
the ground, rather than exploding. Since then, their construction
has become much more complex. Rockets and missiles operate the
same way; the only difference being in the method of stabilization
(either fins or a stick). When the burning fuse enters the end,
the cone-shaped chamber ignites within a fraction of a second. The
shape of this chamber provides a very large surface area for burning to
take place, creating a large volume of gas which is forced out of the
back to create thrust. As a result, the rocket/missile travels in
the opposite direction. Because of the rapid burning, the fuel is
exhausted in a matter of seconds. The casing of the rocket is
usually fairly thick so it can withstand the high pressures of the
burning fuel. The internal time fuse then transmits fire to the
burst charge, which explodes to break open the rocket casing and ignite
the stars or reports inside. |
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ROMAN CANDLES
 Though
roman candles seem like a simple firework, the construction process is quite
complex and difficult. After a clay plug at the bottom, the roman candle
tube consists of alternating layers of lift charge, stars, and delay
compositions. When the fuse enters the tube, it activates a slow-burning
delay composition that makes its way down. Within seconds, the delay
charge reaches the first star, simultaneously igniting both it and the lift
charge below it, which blows the star out of the tube. This ignites
another layer of delay composition, which will light a star and the lift charge
to blow it out a few seconds later. This continues until every star has
been blown out of the tube.
SMOKE DEVICES
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The most famous consumer smoke
device is probably the "smoke ball" or "smoke bomb", a
large ball of clay with a hollow center. Inside the center is a
composition that usually consists of potassium chlorate, lactose, and a
powdered dye. When ignited, this composition burns at a relatively
low temperature, which evaporates the dye into fine particles and
disperses them into the air (so the colored "smoke" isn't
actually smoke at all).
The smoke composition must be
"cooled off" fairly quickly after ignition, or else the dye
particles will react with oxygen to burn up. This is why smoke is
always observed rapidly exiting the burning chamber. If you hold a
smoke device too close to a solid object, the burning particles can't get
away fast enough to cool down. At this point, the device will begin
emitting a flame rather than smoke. |
SNAKES &
STROBES
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Consumer strobes are usually
small paper cups filled with a liquid composition that is allowed to dry.
Strobe composition is a mixture that consists of two main parts: a
composition that reacts easily, and one that doesn't. When the fuse
ignites the composition, the more reactive compound burns to create a
large amount of heat. This heats up the the more difficult to ignite
portion of the mixture, which goes off with a sudden flash once it reaches
ignition temperature. This process repeats itself over and over,
gradually increasing in frequency and producing hundreds of flashes.
In display fireworks, strobe composition
is made into stars and put into either aerial shells or mines.
Snakes are made from a slow, cool-burning
composition that leaves behind a solid, porous ash that "grows"
out of the pellet as it burns.
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SNAPS &
PARTY POPPERS
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These "trick noisemakers" have
many different names, but they're all the same thing. Each of these
pea-sized devices contains a few grains of sand that have been coated with
a tiny amount of impact-sensitive silver fulminate (AgONC), all twisted
together in a piece of tissue paper. When thrown on a hard surface
(or squished between the fingers), the friction of the sand against the
silver fulminate causes the latter to ignite with a quick, loud
"pop".
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| Party poppers are another
well-known and popular noisemaker, especially for children. Inside
of the plastic bottle, just above the neck, there's a small explosive
charge connected to a string. In the "bottle" portion of
the popper are about a dozen tiny rolls of confetti paper. The
string is built into the explosive charge in such a way that when pulled
tight, the charge explodes, which blasts off the paper end cap and sends
out streams of confetti.
Neither pop-its nor party poppers are
actually considered to be consumer fireworks. Rather, they are
considered "trick noisemakers" which, along with toy caps and
cigarette loads, fit into the 1.4S category. Therefore, they can be
sold year-round in most toy shops and shopping centers.
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SPARKLERS
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Old-fashioned sparklers
(left) consist simply of a thin metal wire that has been coated in a
metallic pyrotechnic composition. This slow-burning mixture is
extremely bright and gives of thousands of tiny sparks as it burns down
the length of the wire. Newer, "Morning Glory"
type sparklers (right) consist of a composition-filled tube attached to
a wooden stick. |
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WHEELS AND
SAXONS
| Wheels consist of a
cardboard frame to which are attached several small rockets, or
"drivers". The device is usually attached by a nail to a
wooden post. When the burning fuse enters each driver, the
propellant burns rapidly to give off gas, which is forced out of the
small nozzle to create thrust. This thrust spins the device around
its axis. Unlike most rocket propellants (which are designed to
lift the rocket up into the air and not give color), the propellant used
in wheel drivers burns to produce rich colors, sparks, crackle, etc.
Because the wheel spins so fast, it appears that there are
"rings" of fire. When each driver is exhausted, the fire
is transferred by another fuse to the next driver, which starts up again
and continues the process (usually with a different effect). This
usually happens so fast that the wheel doesn't have time to stop
spinning. |
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