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A vacuum cannon is an interesting physics demonstration that shows how much atmospheric pressure there is at the earths surface, though we do not feel it because our bodies have the same amount of pressure both inside and out. By removing air pressure from inside of a length of pipe the balance with atmospheric pressure is removed, and if the seal is broken on one end air pressure will rush in quickly enough to throw a projectile with a good deal of force.

To learn how I made the vacuum pump used to operate this cannon, take a look at this video: http://youtu.be/UkPLu6mgdWA

The pump is very high quality, and pulls a vacuum much faster than most commercially available pumps, making it ideal for large tasks such as this cannon. Most other pumps would take many minutes to bring a chamber that size down below 25 in/Hg of vacuum.

I first learned of vacuum cannons thanks to this Instructable, and was interested enough to take the project on for myself: https://www.instructables.com/id/Vacuum-Cannon-drives-ping-pong-ball-at-supersonic-/
Can a pump work for the cannon if it is singe stage?
<p>Is there something wrong with this page? I do not see an Instructable anywhere - just lots of sincere comments and a drawing of what looks like a sound suppressor.</p>
Ok thanks! I might just try it...sketch time.
So a question... What if you evacuated the air from the cannon, but pumped that same air into another resovoir that is connected to the vacuum cannon by a ball valve from the back? This way you can use the atmospheric pressure as well as the principles from a regular pneumatic cannon? Would it be worth the trouble?
It wouldn't be worth the trouble with a ball valve, but maybe with a fast acting sprinkler or piston valve.
<p>I came up with an upgrade for your vacuum cannon, I am working on a smaller version of yours, with my modification </p>
Is this more powerful than your coaxial piston cannon ?
I have one all made up and ready to go, and wouldn't you know it, the 40mm pipe isn't actually 40mm, it's some obscure size, but is just referred to as 40mm as it's the closest whole number!! the ping pong balls won't fit!! grrrrr my science class was so disappointed!!
cool
This would be awesome in slo mo. Thanks for sharing
I agree! Get this to the Time Warp gang!
would it work to use some sort of quick valve on the breech end so you only have to change one burst disk? I'm curious if that would work because it would save you a lot of time and tin foil
Neat cannon, voted, and went to my Blog: <br>http://faz-voce-mesmo.blogspot.pt/2013/06/o-molde-ja-feito-e-um-canhao-vacuo-e.html
Very cool. An idea for the foil: Maybe you can build a little square frame out of wood or metal that you tape the foil to. The frame would then slide into a bracket that's always mounted on the pipe. Once you start vacuuming, the foil [might] create a seal on the PCV edge and the frame will keep it from giving in..... This way you can quickly change the burst disks.
Why the swinging mount? It seems you would get a lot more range and accuracy with a rigid mount.
Because making a rigid mount for a pipe that size would have taken more time and resources. That's the only reason. The swinging mount worked fine for the video demonstration. I didn't need anything permanent since chances are i'll be slicing up the pipe for other projects soon anyway.
You could have turned the ladder 90 deg and zip tied it to the frame.
Yes, that would work, but it wouldn't have been as aesthetically pleasing that way. With the pipe hanging from the ladder I could keep it out of view most of the time. I would want something that looked nicer than a ladder if it were going to be ziptied right to the cannon in full view the entire time. Making sure my projects look good to the camera is pretty important to the success of my videos.
Well you have well over a quarter million subscribers, so, what are doing must be working and I am not one to argue with success. It's a great project anyway. Cheers.
Wouldn't a sharp object, or a knife on a long stick work as well as the mallet? <br> <br>Once the structural integrity of the aluminum foil is violated it will shred on its own due to the pressure differential. <br> <br>It looks like the inflow of air would be partially obstructed by the mallet head and cut back on the power on the exit end.
The foil actually tends to tear with a pretty small opening when punctured under pressure. I found a mallet was the only thing that reliably blew out the whole disc at once.
this is really cool. The burst disks look like a pain to use for the long term though. making, taping and replacing each time. Have you thought of using a rubber ring around the back lip so that the cap/projectile seals against it? hold the cap with a clip or pin, then when you release the cap it flies down the tube and instead of a burst disk at the end for it to break though, you can have a rubber flapper valve like on a marshmallow gun. Then you'd also have your hands free to hold the cannon on your shoulder instead of having to mount it and use your hands to swing the mallet.
It's not a bad idea to seal the back of the chamber with the projectile itself, but the problem I see there would be the need to prepare the face of the projectile to make a good seal. That could take a lot of effort and time for something that very well could shatter after being fired once. A rubber flapper valve may work, so long as it is rigid enough to stand up to the few hundred pounds of force that air pressure will be exerting on it, and free moving enough to get well out of the way before the projectile slams into it.
@NightHawkInLight; Hi! I've tweeted this. Excellent video. Excellent shared and collaborative evolution of vacuum cannon and vacuum pump technologies. Best line: Do not stand in front of OR behind of the cannon. Cheers! Site
I appreciate it!
You could use a projectile that seals itself to the pipe, thus not needing the front seal. just my 2c
In it's current state, the vacuum in front of the projectile draws it down the pipe as the air rushes in behind the projectile. &nbsp;Using the front seal allows him to use the entire tube as a vacuum chamber. &nbsp;The author already went over how doing this without the front seal would mean you would have to either:&nbsp;<br> <br> A: put the projectile at the front of the chamber to take advantage of the entire vacuum tube. then you would have a tube that pops the lid off instead of a projectile cannon with a barrel to accurately direct the shot. &nbsp;Most of your energy from the air pressure equalizing &nbsp;will be lost by the time it gets to the end of the tube where your cap/projectile is, so it would just be a little pop. &nbsp; &nbsp;&nbsp;<br> <br> B: put the projectile at the back of the chamber &nbsp;to use the barrel for directing the shot, and only have a small section of the chamber to apply the vacuum to. The projectile would not only have a reduced vacuum to propel it, but it would also be pushing against the air in the tube ahead of it, reducing it's effectiveness even further. &nbsp;Your projectile would be lucky to make it out the end of the barrel.&nbsp;<br> <br> The vacuum cannon doesn't operate by atmosphere rushing in and hitting the projectile like an air hammer. &nbsp;It operates by the air pressure &nbsp;pushing it at high velocity down the tube. &nbsp;The vacuum in front of the projectile is sealed and is drawing the projectile forward into the rapidly shrinking distance all the way to the end of the chamber. &nbsp;There is no atmospheric resistance to push against, there is no loss of energy as the vacuum is unable to equalize without the projectile being pulled in, so the full atmospheric pressure is pushing the projectile the entire distance of the cylinder. &nbsp;Once it breaks the seal, the inertia of the projectile is what carries it out the tube and through the air. &nbsp; &nbsp;The greater the velocity it obtains from the length of the run and the amount of pressure/vacuum, the more inertial energy it will obtain. &nbsp;
Cool stuff. Years ago I got a full appreciation of just what a vacuum can do when I designed ion implanters (used in making semiconductor chips) for a living. For reasons of physics, the beamline on one of those puppies has to be down in the &quot;vacuum of interplanetary space&quot; vicinity. Getting there usually takes a roots blower followed by a turbomolecular pump followed by a cryo pump. <br> <br>One day some genius decided to defeat the safety interlocks on one of the airlocks and open the beamline to atmospheric pressure. Imagine the sound of a kettle drum you could hear from about three miles away. An entire 8&quot; silicon wafer was instantly turned to power and sucked back in powered form all the way to the start of the beamline. As in, &quot;Opps, there went $2MM in under a second...&quot;
is there anyway you could make this without the second seal? <br>
should've been more descriptive. Can you make a canon with no seal in front of the projectile, but just one seal at the back?
It has to be both sides in order to form a sealed vacuum chamber. The only way to not use a rupture disc in the front would be to have the projectile, a 3&quot; end cap in this case, be air tight within the cannon. That is possible using a gasket like the vacuum transport lines they use at home depot etc to send those tubes around but, that would make the chamber significantly smaller due to the fact that the projectile needs to be towards the back in order to use the cannon as a barrel for accuracy.
Always good stuff! Cool project
Wonderful... sounds like a great 4th of July &quot;tool&quot; !!!
awsome! can you then do a vacuum potato cannon?
very very cool!
Couldn't you use a valve instead of the Burst disk at the end that you break the disk at
Could you just fire a burst of &quot;air&quot;?
By the time the air reaches the far end of the pipe it doesn't have enough force to break the second burst disc. It takes a projectile.
There has to be a seal at both ends of the pipe so it will be able to create a vacuum.
Very cool and so easy to make.

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