Without knowing anything at all about them, I decided to try making a toroidal vortex launcher.
I had no clue where to start or how to do it so I just dove right in and made a simple burst disc cannon with a cone for a barrel like this or this.
Needless to say it didn't work. Beyond a few feet it didn't even rustle a paper bag and when I dusted the cone with baby powder, it produced no noticeable rings.
Can anyone with more knowledge on the subject help me out? My best guess is that the cone (funnel) I used is not gradual enough.
Posted: Mon Jan 09, 2012 2:47 pm
by jackssmirkingrevenge
maybe it needs to be a combustion to work like that, simply using a conical barrel?
how about a barrel made of two coaxial tubes, with the air travelling between them...
The one in the video is a combustion, and I believe it works best when it is, due to how fast the pressure is built up.
Posted: Mon Jan 09, 2012 2:57 pm
by Gippeto
Couple wags off the top of my head.
Would think an oriface plate (similar to a flat washer) would be required to initiate the vortex ring.
Would also think a constant taper might be important. Pulling an angle from somewhere dark, I'd try 11-12 degrees.
Posted: Mon Jan 09, 2012 5:41 pm
by MRR
I agree with Gippeto. In all vortex cannon that I have seen so far there was a controlled "bottleneck". You can see it at the example of an airzooka.
You could try to put a expansion chamber in front of the funnel.
Edit:
This video has been posted before but I thought this remix is hilarious...
[youtube][/youtube]
and another...
[youtube][/youtube]
Posted: Mon Jan 09, 2012 9:28 pm
by PVC Arsenal 17
I tried a washer restriction and it didn't change much.
I think I'll start building a combustion version like that guy's prototype in the video above. Any ideas for closing off a combustion chamber so propellant gasses don't escape before firing? (Because there is no projectile)
...Other than burst disks which are inconvenient for rapid firing.
Posted: Mon Jan 09, 2012 9:30 pm
by Lockednloaded
Piston combustion? You could build a tee valve with a light spring holding the chamber sealed. Kinda overkill though if you ask me...
Posted: Tue Jan 10, 2012 12:54 am
by jackssmirkingrevenge
Lockednloaded wrote:Piston combustion? You could build a tee valve with a light spring holding the chamber sealed. Kinda overkill though if you ask me...
Why not just jam a wad of toilet paper in the breech? It doesn't have to hold pressure anyway. Besides, as discussed in another thread, and as jimmy will tell you vehemently with the power of science behind him, in practice it would take ages for the gas to diffuse anyway, so it might not even be necessary.
Also, I've never played Skyrim but I have enough internets in me to know that your launcher probably used to work, but took an arrow to the knee.
Posted: Tue Jan 10, 2012 5:40 am
by pneumaticcannons
Why not just jam a wad of toilet paper in the breech?
That would probably disrupt the toroid...
I think the piston idea would work nicely however and you could always attach a real barrel if you get bored of shooting air
But I don't think making it combustion will make much of a difference. As stated above, the cone probably needs to be a lot more gradual like the smoke ring shooters seen on Bang Goes the Theory and myth busters.
Posted: Tue Jan 10, 2012 11:26 am
by warhead052
Meh, just make it a hybrid if you go with a piston combustion. Same concept, but you just add air. Dunno if it would work though.
Posted: Wed Jan 11, 2012 5:00 am
by Insomniac
I've built a few little vortex cannons before, and I think your problems are that the shape is incorrect on this scale, and you are using way too much air.
One of the most effective ones I made was a long postal tube (maybe 50cm long and 10cm in diameter), with a hole drilled in the cap at the end (about 5cm diameter).
A latex skin was stretched over the other end of the tube. Pulling it back and releasing would send a vortex ring quite rapidly across the room... It could be felt from a good 3 or 4 metres away in still air.
I don't think this would have worked if I had added a large chamber and valve where the latex diaphragm was. The setup I had provided a very rapid pulse of very little air, which formed the ring. I think if you are going to use a pneumatic setup, design it so that your valve dumps behind a captive piston with very little travel... Meaning each shot will move the piston a very short distance very rapidly, generating a sharp, controlled pressure wave in the tube.
