How To Make “Screw-Lock” Sugar Rockets
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How To Make “Screw-Lock” Sugar Rockets

January 18, 2020

For this project I’m going to show you how
to make “Screw-Lock” Sugar Rockets. These PVC rocket motors are powerful, and designed
to help you re-load, and re-launch your “Randomizer” rocket within minutes. They’ve got a built
in parachute ejection system, which will help bring your rockets back safely. And the best
part is, you can make as many as you want, for about a dollar each. Let’s start this project with a box of baking
soda, a bag of powdered sugar, and 100% Potassium Nitrate, stump remover. It’s important to grind the potassium nitrate
into a really fine powder, and the easiest way to do that, is with a small blender, like
the one I found at a local thrift shop for $5. Potassium Nitrate is hygroscopic, meaning
that over time, it’ll absorb moisture out of the air. Which is exactly opposite,
of what we want for our rocket fuel. To make sure your nitrate salt is as dry as
possible, try sprinkling the fine white powder on something like a baking pan, then sticking
it in the oven. I let mine bake at 300ºF (165ºC), for around
30 minutes, to drive off all the moisture, and prepare it for it’s destiny, as my hobby
rocket fuel. While we’ve got that warming, let’s move
on to modifying a few 3/4” x 12” PVC risers, which you can find in the sprinkler section,
of your local hardware store. I clamped a piece of wood to my chop saw exactly
5” away from the blade, which gives me the option to line up the threaded edges, and
cut the tubes cleanly, at exactly 5” long, every time. You can flip the riser
around and do the same thing with the other threaded end as well. This way you get two 5” motor casings, from
one riser. Which will save you time and money, if you’re making more than one. Alright let’s move on to packing the casings,
and for that, you’re going to need a 10” oak dowel. This will be a ramming rod, and a template
as well. And the markings you can see on my stick are designed to make the equivalent, of an
E45-5 rocket motor. Mark a line precisely in the center of the
dowel, at 5”. And measuring from this line, you’ll need
to mark the dowel at 3/4”, 2-1/2”, 5/16”, and 3/4”. Take time to be precise, because
the performance of your rocket motor depends on it. These markings are for the different compositions
we’ll be adding in just a minute, and to double-check you’ve done it right, you should
have 11/16th of an inch left at the tip. Now depending on how, and when, your PVC risers
were manufactured, they may be a little too small for the oak dowel to push all the way
through. If that’s the case, just use a little sandpaper
to knock down the sides of the dowel a bit, until you can slide it all the way into the
casing, with little to no gap at the end. Now before we pack the rocket fuel, it’s
important to rough up the insides of the casings a bit, and for that I’ll be using a flat
metal file. The strength of your clay nozzles and bulkheads
will increase dramatically, just by scoring the bottom inch of your casings, on the inner
walls. And the deeper you can get the scratches, the better it’ll hold. Do the same thing with the top inch of the
casing as well, then set the tube firmly on a hard surface. Because the time has come,
to pack powder. The composition I’m using for my sugar rockets
is a mixture of these three powders. The first glass is filled with finely powdered
bentonite clay, and we’ll be using that first. The cheapest and easiest way to get bentonite
clay is by going to the dollar store and picking up a bag of unscented kitty litter. Use your hobby blender to grind a handful
for around 30-40 seconds, and when your clay is finely powdered, use a funnel to add some
to the tube. Hold the tube firmly to a hard surface, then
hammer the top of the ram rod, as hard as you can. I like to use a rubber mallet, and you’ll
want to give it around 5-10 good whacks to make sure the clay is nice and compacted. Go ahead and repeat the process, and when
the first line on the ram rod, lines up perfectly with the top of the riser, your first clay
plug is done. Let’s move on to adding the “White Mix” next. “White Mix” is the pyrotechnic fuel that’ll
make the rocket fly, and is simply a mixture of 65% Potassium Nitrate, (which is the stuff
we just finished drying in the oven), and 35% Powered Sugar, by weight. Shake the mixture for a couple of minutes
to get the sugar and salt as intimate as possible. I’m shaking by hand, because it’s a good
way to help avoid dangerous amounts of heat or friction, from building up. Remember that this is a highly flammable mixture
and needs to be protected, and treated with respect. Because you don’t want it going
off accidentally. With the fresh white powder thoroughly mixed,
go ahead and ram the fuel into the casing until the second mark on the dowel lines up
perfectly at the top. When it does, you’re ready for cup #3. This third powder is the time delay mix that’ll
control when the parachute gets ejected. The delay mix burns around 1/16” per second,
and you can easily make it by using 20 grams of the “White Mix”, sprinkled with 3 grams
of regular, household Baking Soda. Use a digital scale to make sure your composition
is as accurate as possible, then transfer the delay mix into a plastic party cup, and
gently swirl it around for about a minute, to make sure the baking soda gets thoroughly
worked in. 5/16” of this powder should give us about
a 5 second delay, and when you’ve got the delay mix rammed in tight on top of the “White
Mix”, go ahead and cap it off with another 3/4” of rammed kitty litter clay, like you
did for the nozzle. To double-check you did it right, your casing
should have, 3/4” of clay at the bottom, 2-1/2” of “White Mix” above that, 5/16”
of “Delay Mix” next, followed by 3/4” of rammed clay at the top. All that’s left is to do now, is add the
parachute ejection charge, and drill out the nozzle. I’m using a 3/32” bit for the ejection
charge, and a 7/32” bit for the nozzle. Look closely and you should be able to see
the tips of bits, line up exactly on either side of the “Delay Mix” markings, and
that’s important. And it’s also a really good idea to mark
both ends of the bits in-line with the ends of the motor casing, because that way you’ll
know exactly how deep to drill. If you want to make sure your rockets go as
high as possible, with a parachute that ejects when it’s supposed to, it’s critical that
all your marks and measurements are perfect. If you’re feeling confident they are, then
let’s move on to adding the ejection charge next. The ejection charge goes in above the clay,
but in order to light it off we first need to use the 3/32” bit, to drill a small
hole through the center of the clay, until it reaches the delay mix. It’s really important not to drill into
the delay mix though, because if you do, it’ll compromise the delay time. Use the marking at the back of the bit for
reference, and when you get close, slowly and carefully drill the rest of the hole by
hand. The instant you see a little white powder
on the tip of the bit, you’ll know you’ve arrived. So don’t go any further. Now I picked up a 1lb bottle of FFFG equivalent,
muzzleloading propellant, which seems to work really well for popping out parachutes. Carefully pour a bit of the black powder into
the top, so it covers the clay a few grains deep. Then take your spoon and give the casing a
few gentle taps at the top, to make sure the black powder flows down the hole, and makes
contact with the delay mix. To keep the powder from falling out, give
it one firm tap with your dowel, and you should find it compresses the powder just enough
to keep it in place. Now you will need to cover the powder with
a fire-resistant layer, so it doesn’t get set off accidentally. And for that I’m using
some cellulose insulation, that I scavenged from the attic of my house. Put some fire resistant wadding on top of
the black powder, then ram it down tight, and your ejection charge is complete. With that, there’s only one thing left to
do before our rockets are ready to fly, and that’s to drill out the nozzles. Turn the motor over so the bottom is facing
up, then very carefully place the 7/32” bit exactly in the center, and slowly begin
to drill. It’s important to drill this hole as centered
as possible, and slowly enough that there’s no chance, the fuel can catch fire from the
friction. Keep drilling until you reach the reference
mark at the back of the bit, and with that final step, you’re done. You’ve just created a PVC Sugar Motor, that’ll
screw-lock into position. Just for fun, I made one with an acrylic casing,
so you can see inside, and get a feel for exactly how it’s put together. Lighting it off with a fuse, you’ll see
that when the white mix ignites, it burns incredibly fast, then stops suddenly where
the delay mix begins. And 5 seconds later, pops off the ejection charge. Alright, let’s try testing one of the “Screw-Lock”
motors, with the “Randomizer” rocket, it was designed for. I connected the leads to an electric match
we made in a previous video, then used my N64 Rocket Launch Controller to set it off. With a quick and powerful burst of energy,
the “White Mix” launches the rocket high into the air, then ignites the delay mix,
which slowly burns between 4-7 seconds. When the delay is all used up, the black powder
ignites, popping out the parachute, and floating the rocket safely back to the ground. The best part is it only takes a few seconds
to re-pack the parachute and screw on a fresh new motor. Which means now, you can be all set
for another launch within a matter of minutes. Well now you know how to use baking soda,
kitty litter and a few other common materials, to make sugar powered hobby rockets, for around
a dollar each. But if you don’t feel like spending the
time it takes to make your own, just use commercial rocket motors instead. I tried screwing an Estes E9-6 to the bottom
of the “Randomizer”, and it flew just as well, and over 1,000 ft high. It just cost
5 times as much. Well that’s it for now. If you liked this
project, perhaps you’ll like some of
my others. Check them out at

Only registered users can comment.

  1. Throw the powder in a beaker with a paper towel over it and put it in a vacuum to remove moisture. use to do it in the lab all the time with carbon and other hygroscopic substances

  2. What can we use instead of potassium nitrate or stump remover because it is too expensive give some solution for this

  3. Its amazing america hasn't invented a nonsensical measure of time no one else uses, like inches and ounces. Now I have to convert all these confusing inch fractions to sensible decimals.

  4. Great video, easy to follow, simple visuals. Thanks!

    Who else loves that beautiful blue horizon line at the end when the rocket reaches apogee??? 🙂

  5. What do you do to keep the pvc from lighting and or melting? In my experience a heat shield casing of cement or plaster is the only way to keep the fuel from lighting the pvc; ie why the world uses wax coated craft paper, fire retardant pressed cardboard or aluminium tubing.

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