Everything Explosive!

Here are the projects that I know how to do.  I'm not including the links on where to buy these project kits, because if you want those, go to my previous post (they're in the links).
Always take extreme care when handling explosives, and have an adult on hand at all times.  Most importantly, use your brain and don't be stupid!


Shells:


Fireworks shells are incredibly popular to make. About half of all new fireworks makers tell us they want to learn to make shells first.

Well, if you're going to make fireworks shells, read this article first.

There's no project here. It's just information. But it's what you need to know before you dip your toe into the incredibly rich and exciting world of shell making. This article will show you what types of shells can be made, ways they can be used, and the names of the various parts of shells.

This is important stuff. For instance, we hear from a lot of folks who tell us they want to make their own "mortars."

We've learned the hard way that what they really want are fireworks shells, not mortars (the tubes from which the shells are fired).

Look, I don't want to sound mean about this, but when you get into fireworks-making, it's important to at least sound like you know what you're doing. Believe me, a lot of experienced fireworks makers will avoid you like the plague if you don't know what you're talking about.

Think about it: do you want to be hanging around somebody making explosives, who doesn't even know the name of what he's working on?

I didn't think so.

Shell making is one of the most complex fireworks tasks you can undertake. To make shells that actually work they way you want them to, you need a variety of parts:

• Shell casings (homemade or bought)
  
• Quick match to ignite the lift charge
  
• Coarse black powder (or a rocket motor) for launching the shell
  
• Time fuse or spolettes
  
• Stars or some other inserts in the shell
  
• Fine black powder in one of several forms for bursting the shell

And, of course, you need the knowledge of how to put all these parts together in such a way that your shell actually functions correctly. 
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2 Ways of getting shells up in the air
Whether they are propelled out of mortars high into the sky, or launched on tops of rockets to display at the end of their flights, aerial fireworks shells are designed to fire high into the sky.

Shells launched on rockets

When a shell is attached to a rocket motor to be fired skyward, the shell is referred to as the rocket's "heading." Rocket headings are ignited differently than mortar-fired shells: a rocket heading will typically have a fast-burning "passfire" fuse installed in it, instead of the slow-burning time-fuse in a mortar-launched aerial shell. The passfire fuse gets ignited by the top of the rocket motor when the motor's fuel burns through.



Plastic Can Shell Heading Mounted on a Rocket Motor

Shells fired from mortars

Two important distinctions before we go any further:

• The "shell" is the device which is launched into the air.
  
• The "mortar" is the tube from which the shell is fired.

Reloadable Aerial Fireworks Shell and Mortar
"Reloadable" means that once the shell is fired, another shell can be loaded and fired from the same mortar. The long ignition fuse leads to black-powder lift charge which is attached to the shell in a lift bag. The shell is loaded in the mortar, which is safely secured, and the fuse is ignited at the top of the mortar.

Some consumer fireworks shells are not reloadable. They come as "single-shot" devices, with an ignition fuse installed in the side of the mortar at its base. The black powder lift charge has been dumped loose in the bottom of the mortar, and the shell has been dropped into the mortar on top of the lift powder. Those components are held in place at the bottom of the mortar by pieces of cardboard pressed down on top of the shell.

With these single-shot units, the mortar is secured, the fuse ignited, and one shell is fired from the mortar, which is then thrown away.

Parts of a shell

Basic Parts of an Aerial Fireworks Shell
Here's the sequence of events that happen when a mortar-fired shell does its thing:

• Light Visco ignition fuse.
• The Visco fuse ignites the quickmatch ("shell leader").
• The quickmatch ignites the black powder lift charge.
• The lift charge fires the shell into the air from its mortar and
• The flame from lift powder ignites the shell's time fuse.
• The time fuse burns through to the inside of the shell.
• Inside the shell, the time fuse ignites the shell's burst powder.
• The burst powder lights the stars/garnitures,
• And the shell bursts,
• Throwing the garnitures out far and wide.

Size does matter

The most common designation of a shell is its size. The large shell I am holding in the picture above on the left is a 12-inch shell. The two shells used as rocket headings in the photo above on the right are 8-inchers, and the small reloadable consumer-size shell (beside the yellow mortar) is a 1-3/4-inch shell.

The designated size of a shell is usually determined by the internal diameter of the mortar from which it is designed to be fired (the actual diameter of the shell itself is usually smaller than that).

Some consumer fireworks shells come with mortars as small as 1-inch. Other record-setting shells have been fired from 36-inch, and even 48-inch mortars.

Paper or plastic?

Almost all shells are made from one of two types of material: paper or plastic.

Most budding pyros start out making aerial shells with plastic casings, and the majority eventually switch to using paper for their shells.

Standard size, plastic shell casings have the advantage of being quick, easy, and simple to assemble. But, typically, they do not produce ideal burst symmetry, and they spread plastic debris around the shoot site.

Paper casings are more traditional, produce better shell bursts, and leave only biodegradable paper debris behind. But, the techniques for making paper shells are more involved, take more time, and require more practice to master.



Paper and Plastic Shell Casings

Balls or logs?

Shells can be further classified by shape--spherical or cylindrical. The former are referred to as ball shells, and the latter as cylinder shells.

The casings shown above are used to produce ball shells, like the ones shown at the beginning of this article. Ball shells have their roots in the Orient, starting in Japan, then migrating to China and elsewhere.

Machine-made paper and plastic casings are used to make simple cylinder (also called "can" or "canister") shells.



Plastic Cylinder Shell Casings
More traditional, hand-production techniques are used to produce the largest and most complex of cylinder shells. These techniques originated in Italy and have flourished in Malta, and incorporate paper, paste, and string.


Large Cylinder Shells from the Past and Present

Welcome to fireworks. Will that be a single, double, or triple?

Aerial shells, whether rocket or mortar fired, can have one or more "breaks." A break is one individually-functioning shell. After firing, a multi-break shell will typically display each shell-break either separately in sequence or all at one time.

Here are examples of simple multi-break consumer fireworks ball shells, combined together in one assembly, called "peanut" shells.

In a peanut shell, the time fuses in all the assembled shells (breaks) typically take fire at once, from the lift charge's flame.



Consumer Fireworks "Peanut" Shells
In a "multi-break" cylinder shell, two or more cylinder shells are combined into one assembly. The fuse for the first break takes fire from the quickmatch leader, and each succeeding break taking its fire from the explosion of the previous break.


Traditional Multi-Break Cylinder Shell Construction
The above illustration is taken from the two-part series on cylindrical shell construction techniques by "A. Fulcanelli" in Pyrotechnicas IX and XI. This series is considered to be the "bible" in making Italian style, cylindrical multi-break shells.

Garnitures

What the heck are garnitures?

Garnitures are what an aerial fireworks shell is all about. They are the visual and/or audible effects being carried into the air to be displayed at the perfect moment.

An overall shell description
So, when describing an aerial fireworks shell, we'd want to include:

• How it's getting into the air: rocket heading or mortar fired.
• Its size, given as inches of diameter.
• Material it's made from: paper or plastic.
• Its shape: ball shell or cylinder shell.
• How many breaks it includes: single break, double break, etc.
• The effect it is designed to produce: star shell, shell of shells, etc.

 
Stars and Garnitures 
And, from the dictionary, the root of the word "garniture" lies in the term "garnish," which is defined as "to furnish with beautifying details."

To furnish with beautifying details. Doesn't that sound lovely? That's exactly what we are asking of our various types of garnitures.

There are basically two "sub-assemblies" of a fireworks shell. The first assembly includes the shell leader-fuse, the lift powder, the time fuse, the shell casing, and the burst powder. That whole integrated construct, though, serves one purpose-that of getting the second assembly, the garnitures, up into the air and ignited. Without the garnitures, the shell wouldn't really serve any purpose.

So garnitures refer to the contents of a shell, whether it is used as an aerial shell, a rocket heading, or as an insert in another shell. (In the case of a shell insert to be used inside a larger shell, I suppose the contents of that smaller shell could be referred to as "garnitures of garnitures," or maybe garnitures squared.)

The contents of fireworks mines, and other ground devices-such as cakes, roman candles, and single-shot comets-would also be called garnitures.


Fireworks Stars in a Mine/Mortar Cross Section
Large stars attached to the outside of a shell will create a rising tail as the shell ascends skyward. These large rising tails can also be created for rockets by attaching a large comet to the exterior of the rocket motor or heading, to be ignited when the rocket launches.

Scatter-stars assemblies, described toward the end of this essay, may be attached in pairs, Lincoln-Log fashion, on the exterior of a shell, with graduated time-fuse timings. As the shell rises, these stars will spit out to the side, perpendicular to the shell's trajectory.

Small star shells or reports can be attached to a shell to create "ascending small flowers" or "ascending thunder." Or attaching a whistle can augment a shell's ascent.

Although stars are typically the first components that might come to mind as the contents of a shell, when you stop and think about it there are actually many different varieties of shell inserts. 

It is an overview of these varieties that I'll be presenting here. Information on how to actually make the different kinds of garnitures will be the subject of future projects.

Taken together, all of these devices comprise the largest and most diverse class of components in fireworks making. A very wide range of construction techniques and fireworks effects is included in this category.

The broad category of garnitures can be subdivided into two parts-stars and inserts. The effects, construction, and manufacturing methods of these two categories are quite different. Generally, fireworks stars are increments of pyrotechnic composition bound into pellets. Inserts are bound in paper tubes, paper sheets, or other types of casings. Inserts may themselves contain stars.

Fireworks Stars

When we picture the traditional "flower" display of an aerial shell, the individual points of light and trails of sparks are created by "stars,"-pyrotechnic composition which has been bound into solid pellets.

Simple firework stars are like small charcoal briquettes, with the composition bound together using a binder such as dextrin, some other starch, or a gum.

I remember the first time I dissected a commercial, consumer fireworks shell 20 years ago (something which has to be done very carefully). Inside the shell I found what looked like seeds coated with black powder-black-powder coated, rice-hull burst-powder I later learned. And there were small chunks of "stuff" which I described as small charcoal briquettes in my notebook. This was my first experience with fireworks stars.


Aerial Shell Bursts of Stars with and without Spark Tails

Star Effects

Virtually an endless array of different effects can be produced by fireworks stars. Most of these effects result from the different compositions used to make the stars. You'll hear star formulas described as "charcoal streamer star" or "color star" or "silver-spark streamer" or "strobe star," etc. These different effects are created from the different chemicals in the composition formulas.

Other star effects are the result of different processes used to make the stars: pumped stars, cut stars, box stars, rolled stars, go-getter stars, etc. Many different effects are dependent on the method that is used to make the stars.

The star effects listed below are created simply from different consolidated compositions, with no tubes or wrappings on them. (Composition-filled tube effects will be described in a minute):

• Single color, non-tailed star, in a wide variety of colors
  
• Colored star which leaves a spark tail behind it
  
• Color changing star
  
• Charcoal star which leaves a trail of orange, charcoal sparks
  
• Star which leaves silver or yellow metal spark tails behind it
  
• Unique metal-fueled stars like zinc-granite stars, and electric-spreader stars
  
• Firefly stars
  
• Daytime smoke stars
  
• Crackling stars
  
• Strobe stars
  
• Very fast burning stars
  
• Slow burning stars
  
• Silver or gold glitter stars
  
• Small stars which produce a flower with many points of light
  
• Large stars which produce a few, large, bushy spark trails

Those are just some of the different effects which arise from simply varying the type of composition that stars are made from, or the star size, and/or the process used to manufacture the stars.

Star Manufacturing Processes

When it comes to the different processes employed to make stars, and which can contribute to the variety of the resulting effects, there are three basic methods:

• Cutting stars
  
• Pumping stars
  
• Rolling stars

These three methods produce stars with shapes unique to each method:

• Square stars (usually cubic,) made by cutting star composition
  
• Cylindrical stars made by pumping star composition (although one master pyrotechnist, who is also a master machinist, produces rectangular pumped stars with his special, hand-crafted, rectangular star pump.) Additionally, some folks have experimented with troweling damp, water/dextrin bound star composition into square-divided suspended-ceiling light grids and allowing the cubic stars to dry before ejecting them.
  
• Round stars (spherical) made by rolling star composition in layers, as jaw-breaker candy is made.
  

Cut Stars

Cut stars are quick and easy to make, and have traditionally been the stars of choice in Italian-American style cylinder shells. No special machines or equipment are necessary to make cut stars. This makes star-cutting relatively inexpensive.

Cut stars can be stacked carefully in ball shells, too:


Cut-Stars Stacked in Ball Shell Hemispheres
Cut stars have sharp corners and edges which make for good star ignition. They "lock together" when filled into cylindrical shell casings, enhancing the integrity and strength of the resulting shell.

Since cut star composition has to be pretty wet to make it suitable for cutting, when the comp is bound with water-dextrin, the resulting stars can take longer to dry than stars made with other methods.

Cut stars also have the disadvantage of not having completely consistent sizes, due to the manufacturing method. So, some of them will burn out before others after the shell bursts. They also do not have a very aerodynamic shape, compared to a round/spherical star; so they do not produce as symmetrical a pattern in the sky as round stars do. Cut stars produce only one single color or effect.

Cut stars do have the advantage of being able to be made in any size batch, from a small 2-ounce batch, up through a 30-pound one. And they can be made and primed all in one single step, rather than requiring multiple layers to be built up, often necessary when rolling stars.

Traditional, cube-shaped, water-dextrin bound cut stars can be made in a couple of ways.

For small batches of cut stars, a "pancake" can be made out of the dampened star composition. This flat pancake is then dusted with star prime, and sliced with a thin, straight-edged knife.


"Pancake" Made into Cut Stars
For larger batches of cut stars, a "loaf-box" can be made and lined with waxed paper. Damp star composition is rammed into the box to form a loaf of star comp, and the loaf is ejected from the box-frame. Slices of the loaf are then sliced off of it, and these slices are then cut into stars in the same way the pancake above was.


"Loaf-Box" for Making Large Batches of Cut Stars
One more cut-star method has recently become popular for making relatively small batches of parlon-acetone bound stars-"screen-slicing."

In this method, a parlon-containing star composition is dampened with acetone, which softens the parlon (a synthetic rubber). A pancake of the damp star composition is made, and the patty is pushed through the square holes of a framed stainless-steel screen.

When the patty is pushed through the screen, stars are sliced quickly, and they end up consistently sized, too. Star priming can be incorporated into this one-step slicing method.

These parlon-acetone bound stars make wonderful colors and effects. Best of all, they dry very quickly, so you can use them in fireworks devices after only a few hours.


Screen-Slicing Parlon-Bound Stars and Spreading on Drying Screen

Pumped Stars

Pumped stars are made by packing slightly dampened star composition into a hollow cylinder, either a single-star pump, or a gang pump called a star plate. The star composition is then consolidated with either hand pressure, hand ramming with a mallet, or with the use of a hydraulic or pneumatic press:


Single Star-Pump, Star-Plate, and Pumped Stars
Typically only slightly dampened, water-dextrin bound composition is made into stars with a star pump. So, pumped stars dry much more quickly than comparable water-dextrin bound cut stars. This is especially advantageous when larger stars and comets are being made.

Pumped stars stack very nicely inside cylindrical shell casings, resulting in strong shell integrity. This is advantageous when large, multi-break cylinder shells are being made.

The use of single star pumps or star plates makes this method of star manufacture a little more expensive than star cutting.

Looking at the photo above brings up a question: What is the difference between a comet and a star? Many fireworkers would describe the large diameter pump above as a comet pump, and the plate as a star plate. The large "puck" could be described as a comet, whereas the smaller pellets could be described as stars.

Technically, any fireworks projectile fired individually out of a mortar would be defined as a comet, no matter what size.

And any projectiles, fired in multiples out of shells or mines, would be referred to as stars, once again regardless of their size.

So, it is the use that pumped projectiles are put to-not their size-which technically determines whether they are comets or stars.

But, in practice large projectiles, as singles or groups fired from a shell or mine, are often referred to as comets. And small projectiles, even if they are fired one at a time, as is done from roman candles, are often called stars.

The bottom line is that it's not always cut-and-dried as to whether a projectile is called a star or a comet. And the distinction is not really important.

Although the pumped stars shown above are pellets made with simple tooling and a single-effect composition, more complex stars and comets can also be made.

Small contrasting-effect stars, such as color stars, can be mixed in with the larger comet composition, such as a charcoal-streamer or glitter formula, prior to pressing the comet. When the comet burns, the color stars stream behind it, mixed in and contrasting with the charcoal or glitter tail trailing behind the projectile. This is called a matrix star or comet.

Pumped stars of different compositions may be glued together to form "married" stars. Often their perimeter is then reinforced with some tape or pasted paper. In this way, a projectile with two different effects can be created, say a blue-headed comet with a gold-glitter tail. This combined effect could not be produced with only one composition.

A color-changing pumped star can be made by using a "cavity pump" to pump a star with a depression in one end of it. Once the star is dry, the cavity is filled with a star composition of a different color or effect. That end is then pasted over with paper or tape. The star begins burning from the solid end, exhibiting one effect, which then changes to a different color when the flame front reaches the inner composition.


Cavity-Star Pumps
Crossettes (splitting stars and comets) are made using only one star composition such as a charcoal-streamer or glitter composition. What makes crossettes unique is that the stars begin flying through the air as a standard star would. But then the individual stars split into fragments which fly off in opposite directions.

These stars are made using a crossette pump. These pumps can either resemble the cavity-star pumps shown above, except with smaller diameter cavity-forming projections on their pistons, or they can have "cross-shaped" projections as shown below.


Crossette Pump with Cross-Shaped Cavity-Forming Tip
After a crossette has been pumped and dried, the cavity in it is filled with either a loose powdered explosive, or with a small "firecracker hole shot." Then the star is pasted with paper except for the solid end. The comet burns from that solid end until the explosive is reached. At that point the projectile splits into fragments, which fly away from each other.

This sudden splitting of all the stars in a shell burst is very surprising and impressive, especially if the stars have been carefully crafted so that they all split simultaneously.

So, you can see that different star pumps, compositions, and construction techniques can create different effects in the sky as the pumped stars and comets fly through the air.

Rolled Stars

Spherical stars, often called round stars, are made using a star-roller. These stars have an aerodynamic shape and fly through the air in straight trajectories. The stars can be sized during the rolling process in order to create batches of stars which have very uniform, consistent sizes.

Consistent sizing of rolled stars is highly valued because it results in stars which either change color and/or burn out all at the same time.

One of the really significant advantages of rolled stars is that they can be made with one color composition rolled first, followed by a different color rolled on top of that first one. This produces color changing stars.

Different colors or effects are often rolled up in thin layers and allowed to dry between those layers. So the overall star rolling process can be a lengthy one. But, large batches of stars can be made using the rolling method.

Advanced fireworkers can produce stars which change colors multiple times, or start with a color, go dark for a short time, and then flash on with color again, seemingly out of nowhere.
Rolled stars are the staple of the highly artistic Oriental ball shells.

Star rolling begins with cores such as a small cut stars, lead shot, small seeds, or even little pieces of pasta. An advanced technique for starting star-rolling involves "sprit zing" dry, powdered star composition with a water-filled spray bottle, to create cores on which to continue rolling the stars.

Star composition is layered onto these cores using a star roller. The simplest star roller can be a round or flat-bottomed plastic or metal bowl. The bowl is swirled round and round by hand as the star cores are dampened with sprayed-on water, and more dry star composition is slowly added to "grow" the stars as they roll.

Usually, though, a mechanized star roller of some sort is used. A round container of some sort is rotated by a motor as stars are rolled. Plastic or metal drums, large or small bowls, or even rubber tires, are used in various versions of the star roller.

Using a star rolling machine usually makes this method of star manufacture more expensive than cutting or pumping stars.


Different Types of Star Rollers, Commercial and Homemade
So, in summary, simple fireworks stars can be made from basic compositions bound in pellets with binders. Many different effects can be achieved by varying the star formulas or the process by which the stars are made.

But, there is a whole different class of garnitures, normally referred to as inserts instead of stars.

Garnitures Wrapped in Paper

There is a category of garnitures which consists of pyrotechnic compositions wrapped in paper: pressed in paper tubes, layered between sheets of paper, or contained inside paper casings as small shell inserts.

Small insert shells can be used inside larger shells, to create a "shell-of-shells." These inserts can be filled with any of the various garnitures we are discussing, or they can be filled with a report composition to create simple flashes of light and sound when they burst.

Graceful falling leaves stars are made by troweling, like frosting a cake, soft composition between layers of paper. Once the composition is dry, the sheets of paper-bound composition are cut to size, and one end of the falling-leaves is primed to ensure good ignition. These stars softly break out of a bursting shell, and gracefully drift toward the ground looking like colored falling leaves.

Box stars, sometimes called pillbox stars, are made by pressing some dampened star composition into thin-walled paper tubes. The tubes are made by rolling about 4 turns of kraft paper on a ½-inch diameter rod, and securing the edge of the tube with glue. The star tubes are cut ¾-inch long, and a piece of blackmatch is inserted into the tube with the match sticking out of both ends of the tube.

These tubes are then filled with dampened star compositions which are especially suited to these stars. Because of the embedded blackmatch, which takes and holds fire very well, these stars ignite easily and are not blown blind by a hard shell burst. The compositions used to make them burn a long time, and very brilliantly, resulting in a long duration, dramatic display of drooping brilliant-color stars.


Box Star Insert Construction
Hummers sound like their name implies; these tube inserts create a whirring sound which can be accompanied by a spiraling spray of sparks. A fuel composition is rammed between two clay plugs in a strong-walled cardboard tube. Tangentially-drilled vent holes cause the inserts to spin and whir as the fuel burns.


Hummer Insert Construction
Farfalle inserts (plural for the Italian farfalla), called butterflies in English, are constructed identically to hummers, except the two holes are drilled at the same time, on opposite sides of the tube, straight through the center of the tube. This results in a butterfly-shaped spark spray which causes the inserts to wobble and spin erratically as they fly through the air.

Whirlwinds, also called tourbillion inserts, are made in a fashion almost identical to hummers, except the vent holes are drilled in the tube in a way that makes the insert spin end-over-end as it flies through the air, creating a "cyclone" of sparks.


Whirlwind (Tourbillion) Insert Construction
Serpents are another variation on the theme of clay plugs and fuel rammed in cardboard tubes. Instead of vent holes in the tube, though, a serpent has one vent hole through one of the clay plugs, as would a small rocket motor.

An ignition fuse is installed in that hole to ignite the fuel when the insert is ejected from a fireworks device. The resulting spray of gasses and sparks causes the serpent to fly in a serpentine manner through the sky.

Whistles can be used as pyrotechnic inserts. The shrill whistling sound which results from the whistle fuel can be augmented by bright sparks if metal particles are included in the fuel. Whistle fuel is never hand-rammed, only pressed with an arbor press or hydraulic press.
Whistle Insert Construction
Another creative effect can be achieved with scatter stars. These inserts burst out of the shell "blind," with no immediate visible effect at all. Then, suddenly, out of nowhere, dozens of stars appear, shooting every which way in the sky.


Scatter Stars Insert Construction
Go getters create a similar effect when they fly out of a shell burst, except their vibrant colors are visible right away. Then, suddenly, the self-propelled go getters zip in every possible direction.
The method for making go getters is unique in that a liquid form of star composition is squirted out of a plastic squirt bottle into small paper tubes. A small piece of doubled blackmatch is inserted into each go getter, and the inserts are allowed to dry. The bottom end, which is not designed to ignite, is dipped in Elmer's glue to seal it.  Good Luck with making stars, but don't hurt yourself!

Ghost mines= Colored Fire/Fireballs:

Learn how to make Ghost Mines, flammable colored flame projectors using firework chemicals. At night, this effect looks like a translucent green, blue, or red colored flame shooting into the air. You can use the techniques below to make liquid fireball colored flame projectors or simple colored flame lights burning in steel bowls.  The main ingredient in paint thinner is methyl alcohol, so paint thinner can be used as a substitute for pure methyl alcohol.

Ghost Mines and Colored Flames 

Green mines are easy. You mix a teaspoon or two of the firework chemical, boric acid, in a gallon of methyl alcohol and you're set. The boric acid reacts with the methyl alcohol to give you methyl borate, which is volatile. The boron in the colored flame mine gives it a very pronounced green color. The colored flame mine can be burned in an alcohol lamp or in the open (I would use a stainless steel bowl placed in a second bowl filled with sand).

A piece of steel wool in the bowl of alcohol did the job of a wick. So now we could produce colored flame mines in a rainbow of colors. 

Coloring agents: 

• Red: Lithium chloride (actually any soluble lithium salt)
• Orange: Calcium chloride
• Yellow: Sodium chloride
• Green: Boric acid (borax)
• Blue: (nothing - methyl alcohol burns blue)
• Violet: Potassium iodide
• These chemicals can be found in most chemistry sets

Rockets:

The purpose of fireworks rockets is entertainment. The rocket motor is often designed to provide an entertaining visual and/or audible effect, such as a long glittering or spark tail, or a loud ascending whistle.

Additionally, often the rocket motor is fitted with a "heading," which creates a traditional fireworks display--for example, a loud report, a shell burst of stars, or a display of other types of fireworks inserts--at the end of the rocket's powered flight.

Anatomy of a Fireworks Rocket

Cross Section of a Typical Fireworks Rocket
The diagram above shows the elements of a typical fireworks rocket.
This rocket has three main components.

The rocket motor consists of the paper tube (case), which has a clay nozzle built into the bottom of it to direct the rocket exhaust. It is packed with fuel to provide thrust ("thrust fuel") and a delay ("delay fuel") after the thrust fuel is exhausted. The top of the tube is partially closed by a clay bulkhead which has a "passfire" hole built into it.

The second component is the rocket stick, which is attached to the side of the rocket motor and extends to the left. The rocket stick provides stabilization to the rocket at lift-off and in flight.

Finally, attached to the top of the rocket motor is the heading containing stars and burst. The heading is responsible for the fireworks display seen in the sky as the rocket reaches the top of its climb.

The functions of these various components will be explained in greater detail below.

Size Does Matter

Although it might not seem so at first glance, there is a very big difference between, say, a 3/8-inch ID "magnum" bottle rocket and a 1/2-inch ID rocket motor. Calculating the cross-sectional areas of the two sizes of motor-tubes, and also the total volumes of the tubes, the fact is that a 1/2-inch motor is between 2 and 2.5 times as large (in terms of volume) as a 3/8-inch ID motor. This is easy to see in the next photo.


Homemade Fireworks Rockets

Half-inch, black-powder rockets are a great place to start, and I, personally, enjoy the heck out of making them to this day. They are small enough that they can be made quickly and don't use huge amounts of materials. But they are large enough to really be impressive. They provide that black-powder-rocket "whoosh" as they launch, and they're able to carry a nice payload of stars or other garnitures into the air.

These rockets allow plenty of opportunity to gain experience while enjoying experimentation, research and development, and plain old fireworking fun. You can lift headings the size of consumer fireworks reloadable/artillery shells far into the air with these nice rocket motors. Since they do not require the use of loud black powder lift charges, they are much quieter than mortar-fired shells. And, as opposed to a simple mortar-launched aerial shell, the rocket heading is preceded by the nice rocket-motor "tail" display on the way skyward.

Types of Fuel Used in Fireworks Rockets
The traditional fuel for fireworks rockets is black powder, and it is still used extensively. Black powder produces that characteristic "whooshing" sound, and long tail of charcoal sparks that most fireworks enthusiasts associate with fireworks rockets.

Launch of a 3/4-Inch Black-Powder Rocket

But perhaps the biggest advancement in fireworks rocketry in the past 50 years has been the development of different fuels, other than the traditional black-powder fuel.

"Whistle fuel" is used in whistling rockets, and also in conjunction with other types of fuel as a powerful booster.

Launch of a 3/4-Inch Whistle Rocket, with Report

"Strobe" fuel, used with a whistle-fuel booster, produces one of the most striking visual, and especially audible, effects of any fireworks rocket. A brightly flashing tail is accompanied by loud "popping." It almost sounds like an incoming helicopter.

3/4-Inch Strobe Rocket Taking Off

Rockets with brilliantly colored tails can be made by using color-producing fuels. Such rockets often use whistle fuel as a booster.

Powerful "hybrid fuels" can be made by mixing granulated black-powder fuel with granulated whistle fuel, and pressing that fuel mixture in motor tubes.

Other fuels such as zinc-sulfur fuel, and "sugar" or "candy" fuel--to mention only a couple--have also been developed. So you can see that starting with just the rocket motor, there is plenty of room for creativity and experimentation with fireworks rockets.

Overview of Fireworks Rocket Construction Methods

Rocket tooling, made up of a spindle and rammers (or "drifts"), is used to form the rocket nozzle and form the hollow-cored fuel charge inside the rocket tube.



Two Different Sets of 1/2-Inch Black-Powder Rocket Motor Tooling

The fuel in a fireworks rocket must also be compacted into a solid mass (called a "grain") in order to ensure that burning of the fuel proceeds in a controlled fashion. This process is called "consolidation." In the case of our black-powder rocket, fuel consolidation is also achieved using the tooling, mallet and ramming post. The fuel, made of potassium nitrate, charcoal, and sulfur, is rammed into the paper tube above the nozzle in a series of small "increments" to ensure consistency.
A clay bulkhead with a passfire hole is rammed on top of the finished fuel grain, and finally, a heading is added at the top end of the rocket.

Nozzled versus Nozzleless Motors

Whereas the above mentioned motors have clay nozzles, there are black-powder motors which do not use a clay nozzle. These "nozzleless black-powder" motors have a more powerful black-powder fuel consolidated around a core-forming spindle, without any clay nozzle at the bottom end.

The whistle and strobe motors shown in the previous sections do not use clay nozzles either. They typically do have a core formed up into their fuel grain.

Methods of Consolidating Rocket Fuel

As mentioned above, traditional black-powder motor construction employs hand ramming with a mallet and a solid ramming post.

Tools for Hand-Ramming Rocket Motors
But more sensitive fuels like whistle or strobe composition should not be subjected to the shock associated with ramming. Also it is sometimes desirable to achieve higher densities of compaction. In these cases, mechanical or hydraulic presses are used to press increments of the fuel into the paper tubes.



A Modified 1-Ton Arbor Press for Pressing Rocket Motors


A Homemade Hydraulic Fireworks Press

Means of Stabilizing a Rocket

At the time of launch and during its flight, a rocket must be stabilized to keep it headed in the desired direction, usually straight upwards. There are three different ways to stabilize a rocket:

• Stick stabilization, as shown in the photos above of rocket motors with sticks attached to them.
  
• Fin stabilization, as shown in the photos above of the various rocket with fins on the rocket bodies.
  
• Spin stabilization, as employed in a type of fireworks rocket called a "stinger missile." In these rockets, prior to launch, the rocket motor is spun by exhaust gasses emitting from a tangential spin-hole in the side of the motor-tube.

Spin-Up and Launch of a Spin-Stabilized Stinger Missile

Rocket Heading Types

And, finally, after the rocket motor lifts the rocket skyward and has done its job, a heading that has been installed on the motor's top can display. This can be as simple as a report, or as complex as the 10-inch ball shell on the large rocket shown earlier in this article.

A simple star, or small cluster of them, can be taped to the top of the rocket motor, and they will signify when the rocket's powered flight is completed.

A "bag shell" heading can be constructed of a few turns of kraft paper on the motor's end, filled with black-powder burst charge and a handful of stars.

Or, any complex aerial ball shell or cylinder shell imaginable can be installed on the rocket motor to create a complex aerial fireworks display at the top of the rocket's flight.

Have fun making and lighting all of these cool fireworks, be safe doing it, and remember to check my blog periodically for any updates.  Thanks for reading!