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Whistle Rockets

This Page Updated: December 8th,
2002

Once you're finally get tired of
making boring fireworks that just go "bang",
maybe it's time you try
something a bit more challenging.
Rockets are just about the coolest firework
you can make, simply because they are so universal.
These formulas &
procedures can be used to make plain Skyrockets, powerful Rocket Engines
to
propel giant model rockets, or Rockets with "warheads" that contain Aerial
Shells or large Salutes.

Whistle rockets are
fairly easy to make and are quite powerful for their size. They don't
require a ceramic nozzle like other rockets do, and you can make the
tooling required to build them easily.
The first thing to do it to make
the Whistle Rocket
propellant.

Formula:

WHISTLE
ROCKET

Potassium
Perchlorate

70
grams

Sodium Benzoate

30
grams

Iron Oxide (red)

1
gram

Vaseline (Petroleum Jelly)

3
grams

In addition to the
chemicals listed above, you're going to need a wire mesh spaghetti
strainer,
a can of lacquer thinner, some rocket nozzle mix, a hot melt glue
gun, newspaper,
1 pound rocket cardboard casings, some scrap wood, two
wooden dowels, 3/4" and
1/4" in diameter... as well as some misc. hardware,
glassware, and a few plastic containers.

Hang On!... We're still uploading the
pictures

Making the Propellant

Weigh & screen
30 grams of Sodium Benzoate. It is important that the Sodium Benzoate is as fine
as dust. If yours isn't, you'll have to grind it into a fine, dust-like powder
in a mortar & pestle. Make sure that if you're going to grind it, you're
grinding it alone. NEVER grind 2 chemicals at the same time, it could
lead to a fire or explosion.
After the Sodium Benzoate is a fine powder, run
the mixture through a fine screen again and set the powder aside on a sheet of
paper.
Now weigh & screen 70 grams of Potassium Perchlorate and set that
aside on a sheet of paper.
Do the same for the Iron Oxide.
You should now
have 3 piles of weighed chemicals. Spray the outside of a small plastic
container with Static Guard and dump all 3 piles of chemicals into it.
Snap
on a lid and shake to mix them together. Be aware that the propellant mixture is
now very flammable and should be treated with respect. The Iron Oxide acts as a
catalyst, making the mixture burn much faster than normal... but also increases
its sensitivity to shock & friction. Set this mixture aside for the time
being.

Put a heat
resistant container on your scale and plop (using a couple sticks or spoons) 3
grams of Vaseline into the container.

Place the container on a hot plate
on LOW heat while stirring, until all the Vaseline is melted into a
liquid. DO NOT overheat.

Once the Vaseline
is liquid, remove the container from the heat and sit it on some newspapers or
other surface where it won't burn the table.
Measure out 200ml of Lacquer
Thinner and pour it into the container with the liquid Vaseline while stirring
constantly.
Beware that Lacquer Thinner vapors are flammable, so check around
for any possible sources of ignition or open flames before
proceeding.

Now dump your
container of chemicals into the Vaseline/Lacquer Thinner mix, and keep
stirring!
In a short time, you'll have a thick pink paste. If it's too
thick to stir, you can add a little more Lacquer Thinner to the
mixture.

Now we're going to
spread this paste out on a few sheets of newspaper to allow the Lacquer Thinner
to evaporate.
You MUST do this outside as the Lacquer Thinner vapors
are harmful & explosive. If you were to do this in a closed garage, the
vapors could creep over to your water heater and ignite on the pilot light
inside producing a fire or explosion.

Separate the mass
into pieces and spread out as much as possible to speed drying.

When you can pick
up a piece and it crumbles in your hand, you're ready to granulate it.
Spread
out another couple of sheets of newspaper and put a small amount of mix in your
spaghetti strainer.
Hold this over the newspaper and rub the mixture through
it. It will fall onto the paper as small granules. If it's sticking to the
strainer and not falling onto the paper, you need to let it dry a bit longer
before granulating it. Move the strainer around so just a thin layer is
distributed over the entire newspaper. This speeds drying
considerably.

It will probably
take several hours from this point for all of the Lacquer Thinner to evaporate
from the propellant. Your best bet is not to get to anxious and let it sit
overnight.

Making the Tooling

Like most rockets,
Whistle Rockets require some tooling to compact and form the propellant into a
solid mass.
All rockets must have their propellant in one even, solid block
with no cracks, loose spots or air gaps. If there is but one spot of loose
mixture, one tiny crack or air gap, the rocket will explode. The purpose for the
tooling is to increase the surface area that burns inside the rocket motor. As
seen in the images below, if you were to just pack the tube solid with the
propellant, only the blue area would ignite & start producing thrust when it
was lit.
With the tooling, a cone is pressed into the propellant block that
has much more surface area than without it, so when lit, much more propellant
starts burning, producing much more thrust. It is this big burst of thrust that
really gets the rocket up in the air & moving.

We're going to
make the Whistle Rocket tooling out of some scrap wood and a wooden dowel.
In
contrast, the tooling used to make Black Powder rockets is far more complex,
being made of brass & stainless steel with machined nylon rammers.
This
type of tooling can cost up to $200... but fortunately, Whistle Rockets are a
tad simpler in construction and our cheap wooden rocket tools will work just
fine.

Basically, we're
looking to build something like this:

If you're lucky
enough to own a metal lathe and can build it out of Aluminum, you can really go
first class... but making from wood isn't all that difficult.
There are two
parts, the base and the spindle.

You can use a
larger or small casing, but we've found that a 1 pound rocket casing is about
the best to start with.
The first think you'll need is a wooden dowel that
will slide easily into your casing. If you're using a 1 pound rocket tube, the
inside diameter is 3/4", so you'll need a 3/4" wooden dowel. Make sure that the
dowel will slide into the tube, they sometimes cut dowels a little sloppy and
they wind up too large to fit inside the tube.

Cut and shape the
dowel as in the image below. Try and make everything as straight as possible and
don't be sloppy.
The better this turns out, the better your rockets will
fly.

First grind, sand
or file the end to a point as in the image. Make the point is on center and not
off to the side.

Then cut it off at
00" as shown in the image and sand it smooth.

Using a 3/4" wood
bit, drill a hole about 1/4" deep onto the base wood.

The wood bit will
have also made a center hole. Using an 1/8" bit, drill this center hole out so
it goes all the way through the board.

Put the spindle
into the indent in the board and while holding it there, flip the assembly over
and make a pen mark through the hole in the bottom.
This will put a center
mark on your spindle.

This part is a bit
tough.
Holding the spindle in a vice or similar restraint, drill a STRAIGHT
hole into it using a 1/16" bit. You only have to go in about 1/2", so don't
panic.
We need this pilot hole so that the spindle doesn't crack apart when
we screw it to the base.

Pour a little
Elmer's glue into the indent and insert a thin, 3/4" screw into the hole. Slowly
screw the spindle onto the base until it is tight.
Wipe off any Elmer's' glue
that squeezes out.
If you've made it this far, congratulations! you've made
your Whistle Rocket tooling.

The only other
part of the tooling you'll need is a rammer, For this, just cut off about a 12"
long piece of dowel with flat ends.

Loading the Rocket

Before you start
loading fuel into your rocket, make sure the propellant is dry. You should
hardly be able to smell the Lacquer Thinner since it should have all evaporated.
Don't go by feel... the propellant will always feel greasy or slightly damp,
this is because Vaseline is evenly dispersed through it. The Vaseline is what
make the propellant pack tightly and holds it together. Generally, if you've let
it sit & dry overnight, it's ready to use the next day.

Slip an empty tube
on the spindle and gently slide your rammer into the tube until it hits the top
of the spindle.

Make a mark on the
rammer all the way around. This is the point where you know the spindle &
rammer are touching. When you're packing the propellant into the casing you want
to always keep the rammer above this point. Also make some sort of mark on the
end of the rammer. This lets you know which end is up.

Now put your first
scoop of fuel into the tube.

Slide the rammer
down and compress the fuel. Keep an eye on your mark, do not let the rammer hit
the spindle.
If the mark is coming near the top of the tube, add a little
more fuel and compress again. It is important to compress the fuel as much as
possible
If you're VERY careful, you can GENTLY TAP the rammer
with a hammer to seat & consolidate the fuel.
DO NOT HIT THE RAMMER HARD, OR POUND
ON IT!
If you do,
it will EXPLODE, and
your fingers will leave your body... worst of all, YOUR ROCKET WILL
DAMAGED!

The fuel must be
loaded in small increments. Large increments do no pack well (no matter how hard
you press) and will leave air spaces in the fuel.
When it, fire will
flash into these small gaps and blow the rocket to bits. Just pack the rocket
with fuel in small increments and you'll have no problems.

If you happen to
own a arbor press, you've got it made and can forget the hammer... just crank
the handle and press away.

When you're about
2" from the top, press in about 1/2" of rocket nozzle mix to seal off the tube
and squirt hot melt glue over the top of the rocket nozzle mix. This will lock
it into place and hold back the pressure of the burning fuel. Let the assembly
sit for about 15 minutes to allow the hot melt glue to cool.

Remove the rocket
motor from the spindle with a twisting motion.

Now simply
securely tape a 1/4" wooden stick (about 3 feet long) to the tube and insert a
fuse.

Light it as you
would any skyrocket, inserting the stick in a pipe or other holder that allows
it to move freely and fly.

Advanced Options

Optional ideas
include mixing a small amount of granulated Titanium into the fuel (about 5
grams). When the rocket flies, it will leave a dense trail of bright sparks as
well as make its deafening whistle.
You can also press some moistened colored
star mix into the top of your rocket (after the last scoop of fuel) and then
press in your rocket nozzle mix.
When the rocket reaches it highest point, a
bright colored tail fire will shoot out the back of the rocket before it burns
out.
Making the spindle longer or shorter will increase or decrease the power
of your rocket. If making your tooling from wood, you can make a couple
different size sets for different thrust rockets. If making your tooling out of
Aluminum, you can just tap threaded holes in varying length spindles (making
them interchangeable) on the base.
You can scale up or scale down the size of
the rockets just by using larger or smaller tubes and tooling. Beware though, if
you go larger than about 1" inside diameter, the deafening sound waves from the
engine get so powerful, that they actually will crack the solid block of
propellant causing it to explode right after it lifts off.

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