Episode: 3837
Title: HPR3837: Make a vortex cannon
Source: https://hub.hackerpublicradio.org/ccdn.php?filename=/eps/hpr3837/hpr3837.mp3
Transcribed: 2025-10-25 06:19:05

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This is Hacker Public Radio Episode 3837 for Tuesday the 18th of April 2023.
Today's show is entitled Make a Vortex Cannon.
It is hosted by Mike Ray and is about seven minutes long.
It carries a clean flag.
The summary is How to Make a Vortex Cannon which can extinguish a candle at about ten feet.
Hello, welcome to Hacker Public Radio.
My name is Mike Ray.
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Today we are going to make a Vortex Cannon.
This is a device which we can use to shoot a coherent vortex of air across the room to do
things like blowout.
The candle at several places which is impressive and good fun.
What we're going to need to do this is for the main body of the cannon, a Pringles
tub.
This is the tall cylindrical tube, four-line cardboard tube in which Pringles potato chips
or corn chips, I don't know which, in which they come one end of the tube is sealed with
a thin stainless steel, no tin, it will be thinned something or other and the other end
is the end where you take a lid off, peel back the foil and eat the chips.
So we've got our tube, we also need a party balloon, some strong parcel tape, a drill
and a hole punch to make a nice clean circular hole in the tin end of the tube.
When I say hole punch, I've got in mind a device called a QMAX punch, these are available
from hobby stores or hobby engineering stores or stores like Mapplin in the UK, themselves.
Electronic components and hardware for electronic hobbyists, you can get them in various sizes,
a hole punch of about a centimeter and a half or three quarters of an inch is a suitable
size.
And you need a drill to make a small hole in the bottom end of the tube big enough to pass
through the threaded part of the punch so that you can actually make the hole.
Now what to do, the first thing and most important thing is accuracy in making the hole in the
bottom in the tin end of the tube because the greatest degree of accuracy will produce a cannon
which will fire the most coherent vortex torus of air across the room. It won't work if the
hole is dramatically off centre or if the hole is ragged around its edges if you've made
a pair of scissors or a file or something equally horrible to make the hole.
So we're going to find by whatever means possible to find the exact
or as close as we can get to the exact centre of the tin end of the tube as possible.
Make a small hole with the drill, pass the threaded part of the punch through and punch the hole
out nice and clean. We shouldn't have a circular hole in the centre of the tin end which is nice
has very very nice clean cut edges to it.
At the other end of the tube, the open end where you took the chips out, we're going to use a
party balloon. What you need to do is cut the mouth end of the balloon off a bit where you blow it
up. Stretch the balloon apart and pull it down over the empty end of the tube. Pull it down as
tightly as you possibly can and rep a good amount of parcel tape around the tube to hold the balloon
in place and make sure that some of the parcel tape actually overlaps between the edge of the
balloon and the tube so that it's firmly held in position. What we're trying to achieve is
a drum-like effect at what was the open end of the tube so that the
latex or whatever the balloon is made of and surface makes a nice tight but stretchy surface.
You're going to have to be able to pinch the centre of this. It's quite difficult. There are
other things that you can get that are made of latex which have a little bulb in the end
which you can shove over the top of the tube. I can't remember what they're called.
Anyway so we've made the cannon. We've got a nice circular hole at one end in to tin
and we've got a membrane at the other end formed by the balloon. To fire the cannon
we're going to pinch the centre of the balloon membrane at the end and stretch it out as far
as you possibly can without destroying the cannon or without ripping the balloon. So stretch it
and stretch it back and then let go of it and it will ping back into position and out of the
other end of the cannon you will get a torus of air. What do I mean by a torus? A torus
is the shape of a ring donut with a hole in the middle and that comes out of the end, the circular
hole in the tin at the end of the tube like a smoke ring from a hobbit and it's spinning around.
It's not spinning like the bullet from a rifle barrel. It's spinning in a way
that it suggests it's sort of trying to turn itself inside out like a riding snake.
So if you were to cut it into a section the section would be turning so it's like constantly
constantly turning itself inside out as it travels forward and it's that spinning as the
torus travels forwards that keeps it coherent and keeps it in a fairly tight lump.
And obviously it will break up as it goes across the room particularly if the air is disturbed
but if it's a nice steel room it will travel quite a few feet before it breaks up.
And I've actually made these in the past and blown out the flame on a candle about 10 feet
which is pretty impressive. So that's how to make a vortex cannon. One word of warning
I know it's only shooting a torus of air but do not be tempted either to shoot yourself in the
face at point blank range or to shoot the cat at close range because at very close range it's
going to sting.
Today's show is released on their creative commons, attribution, 4.0 international license.