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 www.thekingofrandom.com